Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
CDP 2018-0040; RAUM RESIDENCE; PRELIMINARY GEOTECHINCAL EVALUATION; 2002-11-27
. : ·: . , ,• ·· .... V ',• . ~: ; ., ... ...... . ,\, _:: . :· .. ·•.,'.,t ... •' ·: .. -: . •" , .. ·.· . .,. •,·. .... : .;:!· .. •·: ·•:,,:,_ .. -. . :,, :·-.. ~--- ,".'• ·,'.•' :.· ... · .. ,": ,· . . ·•,,•. ·. ·. ,: ,I,• •• .... '. :-:. ·: ... 1'····. ··,. . ... • ... , ...... . ···:, ,•, .. ,·, . . ' : 1,.' .•,,.-••. .. · RECO!{l) :ccj'py· . ': l • )',' ' • •. ' • ; ·•,•. . . ~ . . (",: •. ······· .,. •i .:•,·: :-' ': ,•', ~ ·:. ·' ;,., Jhltln.1:-· .. : • • ,', • , I • I . • ' ~· . -::-:---:-,,-. . ,'•, . . _·. ~ .. ,! ... . "::~. :. . . ·. ,•,· . :·.'· . ., . .. . ·· ' .. . : .. . ... ·:·:· .. 'l,,1 ' ,:, -... :·' •,' . : . ,': . ' .·. ~-.. : .... .. . ... ,.:.,.· . \. . '.···.••· ... \ . . . .. :.• . .:': '. :PREI..IMINARY.·G.EQT:EC~N.l,CAL· :l;VALUA. TIOJt .::; :'. : . , •ssts. BLACK RAIL::RoAD/PROP.OSEEfSUBD.iVISION ,' ·:cARLSSAD ,;.SAN :b'i'EGo·:·coHNTY\ CALiFORNIA~ : ... ··.;:'' .. ''.·.-:' ... f': ·,:-:.-:-.:_,·: .:,:·-' .. :·,:,_·. ,•· ........... >., .. . FoA· .. .-"·, .... ··· · ,;, ... , . : .. -:_.·,j•·· .·. . ·. · ...... ·,:··.:_ · .. ·.,·•.· .···: ~:·:~:·._ .:_·' __ .. : .. •-:· :MR~·w1LL1AM AND:.Ms~-CANDACE LYNN ..... : :. ,, ...... ·.·.esi~· a:LAc.J(/RAiL R6AP . '·.' . . : .. · ,• . .•.,·. > ,• '· •',• .... , . ·, _;. :, ." t ·,: qAa:1~s·ai:(it•:¢ALi.e:0FtNlA' ~~oo_~-. · ... , ·. '. ·.··: : ·' . ·: .. <,w~o. 3,46~-~J(-~~--~~-dyEM:~•E·R·.·;~ ,)~~2· i· / .. " ' . . · ... ( •;•,··. ,.-. ' ... l · .. ·, ..... ,;: . -, .. ' -~ ·. ';, .. ::• ., .. ,· ,·, ...... ·, •' . .. '·· .••·: ' .. ~ '· . ·.-. _.,·• .. ; . ' •,• ~ .' · ... ·• ... . ... ,\ -.:: ...... :, . . : ·.' ' ,• . l,. •,• .,r •' :, . ·•.',• .... ·.•. ·~ ", ·:• •, .. '.~ ' . ~ : . .' •· . .-, .. ,; .· 1 . :· .• ' .·•-•· ·~ ~··. \ .. ~. ': . ::.1 •, •': _,_; :_, ·,.·:·,, : .. : :, ''. ••,:.: .. · ;, . !• • ... ··. : .·:· :;' ' ~, .. ·.·. ·. .-.. ·.·' .: .. . . \ ·. < (,·• .. :• '· f' \ • : ..... ... ';•: ..... ··.•, .. .,, •'•' , ..... ·•'{. . ·, : ·' . ~·· • ·. .. ,r ·• :M .' ·:•. · .. •, . . . .. .~ . ',\ •,.• ; ...... .. •,:. . :' . · .. '· .. ~ ~ ' ,. ,\ ,. \-, ;. ,. '• '. ... '• '• ·•,· ". ... ,. : . . .. ·: . . . •.-.. !, .• ...... ,,R£' /': ........ ' ':. {. ·; .· ,· •;.J' --.,'I"'",, .. '; .. • -64 •• • t'_ ·v;E· .,•• '-.:.,.; . .., .· .·_ .... '. -' .. . . . . ":. _Ftiro..-i···2'·0·: .:,_-.: . · .. · · ,, ... ,• · 19 ,. ·. .. -~AIJD ··,DE. v··.• ·. .·. · .. ;·.··.:: . :: : .. ·: · · : .~LOPM°f( _ ·· ... ·. ENGINEER" . NT. · ..... -: .. -. -.· .. lfJG . . ·. .•· G()f~~IK;do~(o,'.· ·•.· ' \ • "Geotechnlcal • Coastal • Geologic • Environmental 57 41 Palmer Way • Carlsbad, California 9201 0 • (760) 438-3155 ·FAX (760) 931-0915 November 27, 2002 Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rail Road Carlsbad, California 92009 W.O. 3460-A-SC Subject: Preliminary Geotechnical Evaluation, 6575 B\ack Rail Road, Proposed Subdivision, Carlsbad, San Diego County, California Dear Mr. and Ms. Lynn: In accordance with your request, GeoSoils, Inc. (GSI), is pleased to present the results of our preliminary geotechnicai evaluation of the subject site. The purpose of our investigation was to evaluate the geologic and geotechnical conditions of the site and their effects on the proposed site development for construction, from a geotechnical standpoint. EXECUTIVE SUMMARY Based on our review of the available data (Appendix A), as well as_ fi~ld exploration, laboratory testing, and geologic and engineering atialysis, the proposed deve1o·pment of the property appears feasible from a geotechnical viewpoint, provided·. the recommendations presented .In.the text of this report are properly incorporated into design and construction ·of the project. The most significant elements of this study are sur,:-imarized below:· · • Undocumented artificial fill, colluvium/topsoil, which are underlain at depth by terrace deposits, were encountered during our investigation. The undocumented artificial fill,. colluvium/topsoil, and weathered near-surface terrace deposits are typically porous, Joose, and subject to settlement. These soils are considered . potentially compressible in their existing state, and have a moderate potential for · hydrocollapse; thus, undocumented artificial fill, colluvium/topsoll, and weat~ered near-surface terrace deposits onsite may settle appreciably under additional fill, foundation, or improvement loadings, and will require removal or recompaction. Depth of removals are outlined in the conclusions and recommendations section of this report. In general, removals will be on the order of ±1 to ±3 feet across a majority of the site, Where settlement-sensitive improvements are proposed. • Groundwater was not encountered onsite and is generally not anticipated to affect site development, providing that the recommendations contained in this report are incorporated into final design and. construction, and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future as a result of site irrigation, poor drainage conditions, or damaged utilities. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. • Our laboratory test results indicate the expansion potential of the onsite soils is generally very low to low; however, onsite soils exhibiting a medium expansion potential may not be precluded. Typical samples of the site materials were analyzed for corrosion/soluble sulfate potential. The testing included determination of pH, soluble sulfates, and saturated resistivity. At the time of this report the results were not available. An addendum to this report will b~ issued when the testing is complete. On a preliminary basis, the use of Type V concrete is not anticipated. • Field mapping in the site vicinity (the relatively new housing tract adjacent to the south), noted the presence of numerous paleoliquefaction (ancient) features ("sand blows," liq·uefaction craters, sand filled fissures and injection dikes, sand vents, etc.), which also likely exist within the site. Potential liquefaction in such areas (in the future) impacting surface improvements is considered very low, provided that the recommendations presented in this report are incorporated into design and construction of this project. Mitigation for structures may be provided by the use of post tensioned slabs. • Based on our review, the site is expected to have a low to moderate risk to be affected by seismic hazards, similar to other areas of California. The seismicity acceleration values provided herein should be co·nsidered during the design of the proposed development. • Adverse geologic conditions ttiat would preclude project feasibility were not encountered. • The geotechnical design parameters provided herein should be considered during project planning design and construction by the project structural engineer and/or architects. . Mr. WIiiiam and Candace Lynn File:e:\wp7\3400\346Da.pge W.O. 3460-A-SC Page Two The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact our office. · Respectfully submitted, BV/JPF/DWS/ki Distribution: (4) Addressee Mr. WIiiiam and Candace Lynn Flle:e:\wp7\3400\3460a.pge Reviewed by: ~,tu David W. Skell Civil Engineer, RC W.O. 3460-A-SC Page Three TABLE OF CONTENTS SCOPI; OF SERVICES . . • . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . .. .. . .. . .. . . . . . . .. 1 SITE DESCRIPTION AND PROPOSED DEVELQPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . 1 FIELD STUDIES ........................................... ·. . . . . . . . . . . . . . . 3 REGIONAL GEOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 EARTH MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... ; . . . . . . 3 Artificial Fill -Undocumented (Map Symbol -afu) . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Colluvium/Topsoil (Not Mapped) ....................................... 4 Terrace Deposits (Map Symbol -Qt) ............................. · ....... 4 FAULTING AND REGIONAL SEISMICITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 . . . Faulting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Se1sm1c1ty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........ : . . . . . . . 6 · Seismic Shaking Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Seismic Hazards .......... •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. OTHER GEOLOGIC HAZARDS ..................................... ~ . • . . . . . . 8 Paleoliquefaction .................................... · ........... ·. . . . 8 GROUNDWATER ............................................. ·. . . . . . . . . . . . 9 · LIQUEFACTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 LABORATORY TESTING ................................................. . Laboratory Standard ................... · . . . . . . . . . . . . . . . . . .......... · .. Expansion Potential ............................. ·. . . . . . . . . . . . . . .... . Shear Testing ...•........................... · ..................... . Corrosion/Sulfate Testing .................... ; . . . . . . . . . . . ........... . "R" V I T t· .. · -a ue es 1ng .................................................. . 10 10 10 10 11 . 11 . DISCUSSION AND CONCLUSIONS ................................. , . . . . . . . 11 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 11 Ea,rth Materials ..........• · ........................ ; ............. ·. . . 11 Undocumented Artificial Fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Colluvium{Topsoil ..................................... • ...... : 12 Terrace Deposits ......................................... -. . . . . 12 Liquefaction .................................. : ............. _.· . . . . . . . 12 Expansion/Corrosion Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Subsurface and Surface Water .. · .. ·. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Regional Seismic Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 EARTHWORK CONSTRUCTION RECOMMENDATIONS .... _ .................... 13 General . . . . . . . . _-. . . . . . . . . . . . . . . . . . . . . . . . . . ; . . . . . . . . . . . . • . . . . . . . . . 13 Site Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Removals (Unsuitable Surficial Materials) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Fill Placement ....... · ...................... , . . . . . . . . . . . . . . . .. . . . . . . . 14 Overexcavation ............................... · . . . . . . . . ; . . . . . . . . . . . . 14 FOUNDATION RECOMMENDATIONS ...................... ·: ................ 14 General . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Preliminary Foundation Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 . POST-TENSION SLAB FOUNDATION RECOMMENDATIONS .................... 15 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Settlement ............... ~ ........... : . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Footing Setbacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . 16 Subgrade Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Perimeter Footings and Pre-Wetting ....................•.............. · 17 · Underslab Moisture Barrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 CONVENTIONAL RETAINING WALLS ....................................... 18 General ................ : ................................. ·. . . . . . . . 18 Restrained Walls . : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Cantilevered Walls · . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Wall Backfill and Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Top of Slope/Perimeter Walls ........................... · . . . . . . . . . . . . . 19 Footing Excavation Observation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Retaining Wall Footing Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 EXTERIOR FLA TWORK ....................................... : . . . . . . . . . . . 20 RECOMMENDED PAVEMENT SECTION ..................................... 21 DEVELOPMENT CRITERIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Landscape Maintenance and Planting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Additional Site Improvements ................... ; ......... · .. ·. . . . . . . . . 22 Trenching .................................................... .-. . . 22 Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Utiilty Trench Backfill ........................... '. . . . . . . . . . . . . . . . . . . . 22 PLAN REVIEW ...........................• ·. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 INVESTIGATION LIMITATIONS ..... ; ..................................... ~. 23 Mr. WIiiiam and Candace Lynn File:e:\wp7\3400\3460a.pge Table of Contents Page Ii FIGURES: Figure 1 -Site Location Map . , .......... · ......... _ ...... · ............... 2· Figure 2 -Californi~ Fault Map .... ; ................... · ...... · . . . . . . . . . . . 6 ATTACHMENTS: Appendix A-References· ........... · . . . . . . . . . . . . . . . . . . . . . . . . . Rear of Text Appendix B -Boring Logs · ............................... _-. . . Rear of Text Appendix C -EQFAULT, EQSEARCH, FRISKSP . . . . . . . . . . . . . . . . . . Rear of Text Appendix D -Laboratory Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . Rear of Text Appendix E -General Earthwork and Grading Guidelines . . . . . . . . . . Rear of Text Plate 1 -Boring Location Map ..................... · .... ·Rear of Text in Folder Mr. WIiiiam and Candace Lynn Flle:e:\wp7\3400\3460a.pge Table of Contents Page Ill PRELIMINARY GEOTECHNICAL EVALUATION 6575 BLACK RAIL ROAD, PROPOSED SUBDWISION CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA . SCOPE OF SERVICES The scope of our services has included the following: 1 . Review of readily available soils and geologic data (Appendix A). 2. Subsurface exploration consisting of the excavation of six exploratory hand auger borings to determine the soil/bedrock profiles, obtain relatively undisturbed and bulk samples of representative materials, and delineate earth material parameters for the proposed development (Appendix 8). · 3. Laboratory testing of representative soil samples collected during our subsurface exploration program (Appendix C). 4. General areal seismicity evaluation. 5. Appropriate engineering and geologic analysis of data collected and preparation of this report. SITE DESCRIPTION AND PROPOSED DEVELOPMENT The site consists of a roughly rectangular shaped parcel, located on the west side of Black Rail Road in the City of Carlsbad, San Diego County, California (see Site Location Map, Figure 1). There Is an existing two-story single-family residence at tt"!e northeast end of the property. The site is surrounded by a relatively new housing developmentto the south. To the north, an existing nursery, and to the west an existing single-family residence. Overall, the property is relatively level, wtth a gently sloping gradient to the west. According to a . USGS 1968 . (photo revised 1975) Encinitas Quadrangle map, the subject site is approxlmat~ly ±377 feet above mean sea level (MSL). It is our understanding that the proposed site development will consist of a ·lot split and preparing three new pads for the construction of one-or two-story single-family residences at the southeast, southwest, and northwest end of the property (see Boring Location Map, Pl~te 1}. Cut and fill grading techniques would be utilized to create d~sign grades for the proposed single-family residential structures, with slab-on-grade floors and continuous footings, utilizing wood-frame construction. Building loads are assumed to be typical for this type of relatively light construction. The need for import soils Is unknown. J.D TopoQuacb Copyricht ~ 1999 Del.orme Yannoulh, ME 040')~ Source Data: USGS Base Map:. Encinitas Quadranglef Callf"orrila--San Dle_go Co., 7.5 Minute Serles (Topographic), -,968 (photo revised 1975), by USGS, 1"=_2000' , 0 2000 4000. w.o. 3460-A-SC Scale Feet N SITE LOCATION MAP Figure 1 FIELD STUDIES Field studies conducted by GSI consisted of six exploratory hand auger borings for evaluation of near-surface soil and geologic conditions. Borings were logged by a geologist from our firm who collected representative bulk and undisturbed samples for appropriate laboratory testing. Logs of the borings are pre·sented in Appendix B. The· locations of the borings are pre~ented on Boring Location Map, Plate 1 . REGIONAL GEOLOGY The subject property is located within a prominent natural geomorphic province in southwestern California known f,lS the Peninsular Rang~s. It is characterized by steep, elongated mountain rangesandvalleysthattrend northwesterly. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks, Jurassic metavolcanlc rocks, and Cretaceous plutonic rocks of the southern California batholith. In the San Diego region, deposition occurred during the Cretaceous period and Cenozoic era in the continental margin of a forearc bas.in. Sediments, derived from Cretaceous-age plutonic rocks and Jurassic-age volcanic rocks, were deposited into the narrow, steep, coastal plain and continental margin of the basin. These rocks have been uplifted, eroded · and deeply incised. During early Pleistocene time, a broad coastal plain was developed from the deposition of marine terrace deposits. During mid to late Pleistocene time, this · plain was uplifted, eroded, and incised.· Alluvial deposits have since filled the lower valleys, and young marine sediments are currently being deposited/eroded within coastal and beach areas. EARTH MATERIALS Earth materials encountered on the site consist of undocumented artificial fill, colluvium/topsoil,. and terrace deposits. Artificial FIii -Undocumented (Map Symbol -afu) An area in the eastern portion of the property appears to consist of relatively recently placed . undocumented fill, likely associated with the improvements of Black Rail Road and the development of the e~lsting single-family residence. Based on· our exploration, thickness of-this fill is estimated to be on the order of ± 1 to ±3 feet or so. Based on their appearance and classification, these fill soils appeared to have been locally derived and generally consist of moist, loose, silty sand. As a result of the potentialiy compressible nature of these soils, they are considered unsuitable for support of structures and/or improvements in their existing state. Accordingly, these soils will require removal and recompaction if settlement- sensitive improvements are proposed within there influence. Mr. William and Ms. Candace Lynn 6575 Black Rall Road, Carlsbad File:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page3 Colluvlum/Topsoll {Not Mapped) Surficial colluvium/topsoil was encountered in the majority of borings excavated onsite. Colluvium/topsoil materials consisted of orange brown, silty sand. The materials generally ·were moist and loose with roots and rootlets. The thickness of the coUuvium/topsoil is on the order of ± 1 foot. These surficial soils are considered unsuitable for support of additional fill and/or settlement sensitive Improvements in their existing state, owing to their potential for hydrocollapse. Accordingly, these soils will require removal and recompaction if settlement-sensitive improvements are proposed within their influence. Terrace Deposits (Map Symbol -Qt) The Quaternary-age terrace deposits underlie the entire site at depth. As encountered, the • terrace deposits generally consist of orange brown, silty sand, and are medium dense to dense with depth. As a result of the relatively loose and weathered condition of the upper ±½ to ± 1 foot, these weathered sediments should be removed, moisture conditioned, and recompacted and/or processed in place, should settlement-sensitive improvements be proposed. FAUL TING AND REGIONAL SEISMICITY Faulting The site is situated in an area of active as well as potentially-active faults. Our review indicates that there are no known active faults crossing the site within the areas proposed for development (fan and Kennedy, 1996), and the site is not within an Earthquake Fault ~~-· . . There are a number offaults in the southern Californi~ area that are considered active and would have an effect on the site in the form of ground shaking, should they be the source of an earthquake. These include-bl.it are not limited to:....the San Andreas fault, the San Jacinto fault, the Elsinore fault, the Coronado Bank fault zone, and the Newport-Inglewood/Rose Canyon fault zone. The location of these and other major faults relative to the site are indicated on Figure 2. The possibility of ground acceleration or shaking at the site may be considered as approximately similar to the southern California region as a whole. . Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page4 \ ~ ~ I SAN FRANCISCO SITE LOCATION ( + ): Latitude -33. 1122 N Longitude -117. 2879 W LYNN PROPERTY CAL IFORN IA W.O. 3460-A-SC 0 50 100 SCALE (Miles) Figure 2 The following table lists the major faults and fault zones in southern California that could have a significant effect on the site should they experlenc~ significant activity: · Coronado Bank -Agua Blanca . 21 (34) Eislnore 25 (39) . La Nacion 20 (33) Newport -Inglewood -Offshore 10 (16) Rose Canyon 5 (9) 31 50 Se Ism I city The acceleration-attenuation relations of Campbell and Bozorgnia (1994) and Campbell (1993) have been incorporated into EQFAULT (Blake, 1989). For this study, peak horizontal ground accelerations anticipated at the site were determined based on the random mean plus 1 -sigma attenuation curve.and mean attenuation curye de_veloped by those authors. EQFAULTis a computer program by Thomas F. Blake (1989), which performs deterministic seismic hazard analyses using digitized California faults as earthquake sources. The program estimates the closest distance between each fault and a user-specified file. If a fault is found to be within a user-selected radius, the program estimates peak horizontal ground acceleration that may occur at the site from the upper-bound ("maximum credible") and "maximum probable" earthquakes on that fault. Site acceleration (g) is computed by any of the 19 user-selected acceleration-attenuation relations that are contained in EQFAULT. Computer printouts of the EQFAULT program are included in Appendix C. Based on the above, peak horizontal ground accelerations from an upper bound ("maximum credible") event may .be on the order of 0.58g to 0.68g, and a "maximum probable" event may be on the order of 0.36g to 0.38g, assuming an earthquake, on the Rose Canyon fault zone, located approximately 5.4 miles from the subject site. Historical site seismicity was evaluated with the acceleration-attenuation relations of Campbell and Bozorgnia (1994) and the computer program EQSEARCH (Blake, 1989, updated.to December, 2001 ). This program performs a search of the historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100 mile radius, between the years 1800 to 2001. Based on the selected accelt3ration-attenuation relationship, a peak horizontal ground acceleration Is estimated, which may have effected the site during the specific event listed. Based on the available data and the attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 to 2001 was 0.30g. Mr. Wllllam and Ms. Candace Lynn 6575 Black Rall Road, Carlsbad Flle:e:\wp7\3400\3460apge W.O. 345·0-A-SC November 27, 2002 Page6 Site specific probability of exceeding various peak horizontal ground accelerations and a seismic recurrence curve are also estimated/generated from the historical data. Computer printouts of the EQSEARCH program are presented in Appendix C'. A probabilistic seismic hazards analyses was performed using FRISKSP (Blake, 1995) which models earthquake sources as 3-0 planes and evaluates the site specific probabilities of exceedance for given peak acceleration levels or pseudo-relative velocity levels. Based on a review of these data, and considering the relative seismic activity of the southern California region; a peak horizontal ground acceleration of 0.30g was calculated. This. value was chosen as it corresponds to a 1 O percent probability of exceedance In 50 years (or a 475-year return period). Computer printouts of the FRISKSP program are included in Appendix C. Seismic Shaking Parameters Based on the site conditions, Ch~pter 16 of the Uniform Building Cod~ (International Conference of Building Officials, 1997'), the following seismic parameters are provided: Seismic zone (per Figure 16-2*) . 4 Seismic Zone Factor (per Table 16-1*) 0.40 Soll Profile Type (per Table 16-J*) So Seismic Coefficient c. (per Table 16-Q*) 0.44 N. Seismic Coefficient Cv (per Table 16-R*) 0.64 NV Near Source Factor N. (per Table 16-S*) 1.0 Near Source Factor Nv (per Table 16-T*) 1.05 Seismic Source Type (per Table 16-U*} B Distance to Seismic Source 5.4 mi (8. 7 km) Upper Bound Earthquake Mw6.9 * Figure· and table references from Chapter 16 of the Uniform Building Code (1997). Seismic Hazards The following list includes other seismic related hazards that have been considered during our evaluation of the site. The hazards listed are considered negligible and/or completely mitigated as a result of site location, soil characteristics and typical site development procedures: Mr. Wllllam and Ms. Candace Lynn 6575 Black Rall Road, Carlsbad File:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November27,2002 Page7 • . Liquefaction • Dynamic Settlement • Surface Fault Rupture • Ground Lurching or Shallow Ground Rupture • Tsunami It is important to keep in• perspective that in the event of a "maximum probable" or "maximum credible" [upper bound] earthquake occurring on any of the nearby major faults, strong ground shaking would occur in the subject site's general area: Potential damage to any structure(s} would•likely be greatest from the vibrations and impelling force caused by the inertia of a structure's mass, than from those induced by the hazards cons_idered above. This potential would be no greater than that for other existing structures and improvements . . in the immediate vicinity. OTHER GEOLOGIC HAZARDS Mass wasting refers to the various. processes by which earth materials are moved down slope in respons~ to the force of gravity. Examples of these processes include slope creep, surficial failures, and deep-:seated landslides. Creep is the slowest form of mass wasting and generally involves the outer 5 to 1 O feet of a slope surface~ During heavy rains, such as those in 1969, 1978 .. 1980, 1989, 1993, and 1998 creep-affected materials may become saturated, resulting in a more rapid form of downslope movement (i.e., landslides and/or surficia! failures}. The site topography is relatively flat-lying, no such slopes are proposed, and indications of deep-seated landsliding on the site were not observed during our site reconnaissance. Therefore, the potential for seismically induced landsliding is considered low to nil. Paleollquefactlon Numerous sediment-deforming features were observed on the s·outhern adjacent housing tract. As indicated in Obermeier (1996}, these features have: sedimentary characteristics that are consistent with an eart~quake-induced liquefaction origin; namely, there is evidence of an upward-directed hydraulic force that was suddenly applied and was of short duration; sedimentary characteristics consistent with historically documented observations · of the earthquake-induced liquefaction processes, in a similar physical setting (dikes, sills, vented sediment, lateral spreads, and some types of soft sediment deformations}; occur in groundwater settings where suddenly applied, strong hydraulic forces of short duration could not be reasonably expected except from earthquake-induced liquefaction (i.e., non- artesian conditions and non-seismic landsliding are not present); similar features occur at multiple locations, in similar geologic and groundwater settings (Kuhn, et al, 1996}; and the evidence for the age of the features supports the interpretation that they formed·in one or more discreet, short episodes that individually affected a large area and that the episodes·· were separated by relatively long time periods during which no such features were formed. Based on our review and field investigation of the southern adjacent housing tract, the sediment-deforming features fall into the above categories, and are thus classified as Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rall Road, Carlsbad File:e:\wp7\3400\3460a.pge C.o.n~nilc. JnAP.. W.O. 3460-A-SC November 27, 2002 Pages paleoliquefaction features. Af3 a result of this regional paleoliquefaction condition, post- tension foundation systems are recommended. GROUNDWATER Subsurface water was not encountered within the property during field work performed in · preparation of this report. Subsurface water Is not anticipated to adversely affect site development, provided that the recommendations contained in this report are incorporated Into final design and construction. These observations reflect site conditions at the time of our investigation and do not preclude future changes in local groundwater conditions from excessive irrigation, precipitation, or that were not obvious, at the time of our investigation. · Seeps, springs, or other indications of a high groundwater level were not noted on the subject property during the time of our field investigation. However, seepage may occur locally {as a result of heavy precipitation or irrigation) in areas where fill soils overlie terrace deposits. Depth to the regional water table .is anticipated to be greater than 50 feet below existing grade. LIQUEFACTION Liquefaction describes a phenomenon in which cyclic stre·sses, produced by earthquake induced ground motion, create excess pore pressures in relatively cohesionless soils. These soils may thereby acqiJire a high degree of mobility, which can lead to lateral movement sliding, consolidation and settlement of loose sediments, sand boils, and other damaging deformations. This· phenomenon occurs only below the water table, but after liqu~faction has developed, it can propagate upward into overlying, non-saturated soil, as excess pore water dissipates. Liquefaction susceptibility is related to numerous factors and the following conditions must exist for liquefaction to occur: 1) sediments must be relatively young in age and not have developed large amount of cementation; 2) sediments must consist mainly of medium to fine grained relatively cohesionless sands; 3) the sediments must have low relative density; · 4) free groundwater must be present in the sediment; and 5) the site must experience seismic event of a .sufficient duration and large enough magnitude, to induce straining of soil particles. At the subject sile, two to four of the five concurrent conditions which · are necessary for liquef~ction to occur exist or have the potential to exist. Accordingly, the potential for liquefaction in the areas currently proposed for development is considered very low. Mitigation of liquefacti<;>n potential is also mitigated by post-tensioned foundation systems and the incorporation of our grading guidelines and foundation design parameters lr,to project planning design and construction. · Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad ·File:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page9 LABORATORY TESTING Laboratory tests were performed on a representative sample of representative site earth materials in order to evaluate their physical characteristics. Test procedures used and results obtained are presented below. · Laboratory Standard The maximum density and optimum moisture. content was determined for the major soil type encountered in the borings. The laboratory standard used was ASTM D-1557. The moisture-density relationship obtained for this soil is shown in the following table:· B-1 @0'-1' Sil Sand, Oran e Brown 131.0 9.0 Expansion Potential Expansion testing was performed on representative samples of site soil in accordance with USC Standard 18-2 (USC, 1997). The results of expansion testing are presented in the following table: 8-4@ 1'-4' <5 Ve Low to Low · Shear Testing Shear testing was performed on a representative, "remolded" sample of site soil in general accordance with ASTM test method D-3080 in a Direct Shear Machine of the strain control type. The shear test results are presented as in Figure D-1 in Appendix D, and as follows: B-1@0'-1' remolded 162 Mr. William and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp7\3400\3460a.pge ·29 155 29 . W.O. 3460-A-SC November 27, 2002 f>age 10 Corrosion/Sulfate Testing Typical samples of the site materials were analyzed for corrosion/soluble sulfate potential. . The testing included determination of pH, soluble sulfates, and saturated resistivity. At the time of this report the results were not available. An addendum to this-report will be issued · when the testing is complete. "R"-Value Testing A representative sample was collected for "R" -value testing. Laboratory test results indicate an "R" -value of 73. DISCUSSION AND CONCLUSIONS General Based on our field exploration, laboratory testing, and geotechnical engineering analysis, · it is our opinion that the subject site is suitable for the proposed development from a geotechnical engineering and geo_logic viewpoint, provided that the recommendations presented in the following sections are incorporated into the design and construction phases of site development. The primary geotechnical concerns with respect to the proposed development and improvements are: • Earth materials characteristics and depth to competent bearing material. • Liquefaction potential. • Expansion and corrosion potential of site soils. • Subsurface water and potential.for perched water. • Regional seismic activity. The recommendations presented herein consider these as well ·as other aspects·ofthe site. In the event that any significant changes are made to proposed site development, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the recommend~tions of this report verified or modified in writing by this office. Foundation design parameters are considered preliminary until the foundation design, layout, and structural loads are provided to this office for review. Earth Materials Undocumented Artificial FIii Undocumented Artificial Fill materials are generally moist and loose, susceptible to hydrocollapse and do no~ meet the current industry minimum standard of 90 percent (or greater) relative compaction. Recommendations for the treatment of undocumented artificial fill are presented in the earthwork section of this report. Mr. William and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page 11 Colluvlum/Topsoll Colluvium/topsoil materials are generally dry and loose, susceptible to hydrocollapse and do not meet the current industry minimum standard of 90 percent (or greater) relative compaction. Recommendations for the treatment of colluvium/topsoil are presented in the earthwork section of this report. Terrace Deposits Terrace deposits will be encountered during site earthwork. The upper±½ to± 1 foot of the terrace deposits are weathered and should. be removed and recompacted. Below the weathered zone, the materials are considered competent to support settlement-sensitive structures in their existing state. Liquefaction Liquefaction potential throughout a majority of the site is considered relatively low, · assuming that the recommendations presented In this report are properly incorporated into the design and construction of the project. Previous liquefaction of terrace deposits, evidenced by the observed paleoliquefaction features is not anticipated to· recur, primarily due to the observed cementation of the earth materials comprising the features and surrounding terrace deposits and the lack of groundwater. Mitigation for liquefaction may be provided by the use of post tensioned slabs. Expansion/Corrosion Potential Our laboratory test results indicate that soils with a Very loW to low expansion potential (expansion index [E.1.] range o to 50). However, onsite soils exhibiting a medium expansion potential may not be precluded. This should be considered during _project · design. Foundation design and construction recommendations are provided herein for very low to medium expansion potential classifications. Subsurface and Surface Water Subsurface and surface waters, as discussed previously, are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that . prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along fill/formational contacts and along zo.nes of contrasting permeabilities may not be · precluded from occurring in the future during gr~ding, or as a result of site irrigation, poor drainage conditions, or damaged utiiities. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. · Mr. Wllllam and Ms. Candace Lynn 6575 Black Rall Road, Carlsbad File:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page 12 The groundwater conditions observed and opinions·generated were those atthe time of our investigation. Conditions may change with the introduction of irrigation, rainfall, or other factors that were not obvious at the time of our investigation. Regional Seismic Activity The seismic acceleration values provided herein should be considered during the design of the proposed development. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All grading should conform to the guidelines presented In Appendix Chapt~r A33 of the Uniform Building Code, the requirements of the appropriate City and County, and the Grading Guidelines presented in Appendix E, except where specifically superseded in the text of this report. Prior to grading, a GSI representative should be present at the preconstruction meeting to provide additional grading guidelines, if needed, and review the . earthwork schedule. . . . During earthwork construction all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representa,tive(s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and if warranted, modified and/or additional recommendations will be offered. All applicable requfrements of local and national construction· and general industry safety orders, the Occ~pational Safety and Health Act, and the Construction Safety Act should be met Site Preparation Debris, vegetatio.n and other deleterious material should be removed from the building area prior to the start of grading. Sloping areas to receive fill should be properly benched In accordance with current industry standards of practice and guidelines specified in the Uniform Building Code. Removals (Unsuitable Su.rflcial Materials) As a result of the relatively loose condition of undocumented artificial fill, colluvium/topsoil, and near-surface weathered terrace deposits, these materials should be removed and recompacted in areas proposed for settlement sensitive structures, or areas to receive compacted fill.· At this time, removal depths on the order of ± 1 to ±3 feet should be · anticipated; however, locally .deeper removals may be necessary. Removals should be completed below a 1 :1 projection down and away from the outside bottom edge of any settlement sensitive structure and/or limits of proposed fill. Once removals are completed, the expos~d bottom should be reprocessed and compacted. Mr. William and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad Ale:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 · Page 13 FIii Placement . Subsequentto ground preparation, onsite soils may be placed in thin (±6-inch) lifts, cleaned of vegetation and debris, brought to a least optimum moisture content, and compacted to achieve a minimum relative compaction of 90 percent. If soil importation is planned, a sample of the soil Import should be evaluated by this office prior to importing, in order to assure compatibility with the onsite site soils and the recommendations presented in this report. Import soils {if any) for a fill cap should be very low expansive (E. I. less than 20). The use of subdrains at the bottom of the fill cap may be necessary, and subsequently . recommended based on compatibility with onsite soils. Overexcavation In order to provide for the uniform support of the planned structure, a minimum 3-foot thick fill blanket is recommended for the graded pads. Any cut portion of the pads for the residences should be overexcavated a minimum 3 feet below finish pad grade. Areas with planned fills less than 3 feet should be overexcavated in order to provide the minimum fill thickness. Fill thickness should not exceed a ratio of 3: 1 (maximum to minimum} across the building areas. This overexcavation should be performed 5 feet outside th_e proposed building footprint. · FOUNDATION RECOMMENDATIONS General In the event that the information concerning the proposed development plan is not correct, or any changes in the design, location or loading conditions of the proposed structure are made, the conclusions and recommendations contained in this report shall not be considered valid · unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. It is our understanding that slab-on-grade construction is desired for the proposed development. The information and recommendations presented in this section are not meant to supersede design by the project structural engineer. Upon request, GSI could provide additional input/consultation regarding soil parameters, as related to foundation design. Preliminary Foundation Design Our review, field work, and laboratory testing indicates that onsite soils have a very low to low to possible medium expansion potential. Preliminary recommendations for. foundation design and construction are presented below. Final foundation recommendations should be provided at the conclusion of grading, and based on laboratory testing of fill materials exposed at finish grade. Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rall Road, Carlsbad Flle:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page 14 POST-TENSION SLAB FOUNDATION RECOMMENDATIONS Post-tensioned slab foundation systems may be used to ·support the proposed buildings .. Baseq on the regional paleoliquefaction features, post-tensioned slab foundations are recommended exclusively. · General In the event that information concerning the proposed developrrtent plan is not correct, or any changes in the design, location or loading conditions of the proposed structure are made, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. · The information and recommendations presented in this section are not meant to supersede design by a registered structural engineer or civil engineer familiar with posMensioned slab• design or corrosion engineering consultant. Upon · request, GSI could provide additional data/consultation regarding soil parameters as related to post-tensioned slab design during grading. Th~ post-tensioned slabs should be designed in accordance with the Post- Tensioning Institute (PTI) Method. Alternatives to the PTI method may be used if equivalent systems ·can be proposed which accommodate the angular distortions, expansion potential and settlement noted for this site. · Post-tensioned slabs should have sufficient stiffness to resist excessive bending due to non- uniform swell and shrinkage of subgrade soils. The differential movement can occur at the corner, edge, or center of slab. The potential for differential uplift can be evaluated using the 1997 Uniform Building Code Section 1816, based on design specifications of the Post- Tensioning Institute. The following table presents suggested minimum coefficients to be used in the Post-Tensioning Institute design method. · · Thornthwalte Moisture Index · -20 inches/year Correction Factor for Irrigation 20 Inches/year Depth to Constant Soil Suction 5feet Constant Soil Suction loft 3 .. 6 . The coefficients are considered minimums and may not be adequate to represent worst case conditions such as adver~e drainage and/or improper landscaping and maintenance. The above parameters are applicable provided structures have gutters and downspouts and positive drainage is maintained away from structures. · Therefore, it is· important that information regarding drainage, site maintenance, settlements, and effects of expansive soils be passed on to future owners. · · Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rall Road, Carlsbad File:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November27,2002 Page 15 Based on the above parameters, design values were obtained from figures or tables of the 19~7 Uniform Building Code Section 1816 and presented in Table 1. These values may not be appropriate to accountfor possible differential settlement of the slab due to other factors (i.e., fill settlement); If a stiffer slab is desired, higher values of ym may be warranted. It should be noted that laboratory data for onsite soils indicates that these materials are very low to low, to possibly medium expansive. · TABLE 1 POST TENSION FOUNDATIONS em center lift 5.0 feet 5.5feet em edge lift 2:S feet 2.7feet Ym center lift 1.1 inch 2.0 inch Ym edge_ lift 0.35 inch 0.55 inch Bearing Value <1> 1,200 psf 1,200 psf Lateral Pressure 250 psf 250 psf Subgrade Modulus (k) . 159 pci/inch 1 oo pci/inch Perimeter footing embedment <2> 12inches 18inches <1l Internal bearing values within the perimeter of the post-tension slab may be increased by 300 psf for each foot of embedment below the bottom of the slab, to a maximum of 2,500 psf. <2> As measured below the lowest adjacent compacted subgrade surface. . (3J Foundations for ve low ex anslve soil conditions ma use the California Method s anabili method . Settlement In addition to designing slab systems (PT or other) for the soil conditions, described herein, the estimated settlement and angular distortion vaiues that an individual structure could be. subject to should be evaluated by a structural engineer as 1 inch total settlement with a differential settlement of¾ inch over 40 feet. Design values for differential settlement and the PTI methodology represent two ·separate conditions and are not considered additive. Footing Setbacks All footings should maintain a minimum 7-foot horizontal setba~k from the base of the footing to any descending slope. This dista11ce is measured from the footing face at the bearing elevation. Footings should maintain a minimum horizont~I setback of H/3 (H=slope height) from the base of the footing to the descending slope face and no less than 7 feet, nor need Mr. Wllllam and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page 16 . to be greater than 40 feet. Footings adjacent to unlined drainage swales should be deepened to a minimum of 6 inches below the Invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below . a 1 :1 projection from the heel of the wall. Alternatively, walls may · be designed to · accommodate structural loads from buildings or appurtenances. Subgrade Preparation The subgrade material should be compacted to a minimum 90 percent of the maximum laboratory dry density. Prior to placement of concrete, the subgrade soils should be we.II moistened to at least optimum moisture content and verified by our field representc,3.tive. Perimeter Footings and Pre-Wetting From a soil expansion/shrinkage standpoint, a fairly common contributing factor to distress of structures using post-tensioned slabs is a significant fluctuation in the moisture content of soils underlying the_perimete~ of the slab, compared to the center, causing a ~dishing" or · "arching" of the slabs. To mitigate this possible phenomenon, a combination of soil pre- wetting and construction of a perimeter cut-off wall grade beam should be employed. Deepened footings/edges around the slab perimeter must be used to minimize non·-uniform surface moisture migration (from an outside source) beneath the slab.· Embedment depths are presented in Table 1 for various soil expansion conditions. The bottom of the deepened footing/edge should be designed to resist tension, using cable or reinforcement per the structural· engineer. Other applicable recommendations presented under conventional foundation recommendations in the referenced report should be adhered to during the desiQn and construction phase of the project. Floor slab subgrade should be at, or above the soils optimum moisture content to a depth of 12 inches for very low to low expansive soils, and 120 percent optimum moisture content to a depth of 18 inches for medium expansive soils, prior to pouring concrete. Pre-wetting . of the slab-,subgrade ~oil prior to placement of steel and concrete will likely be recommended and necessary,· in order to achieve optimum moisture conditions. Soil moisture contents should be verified at least 72 hours prior to pouring concrete. Underslab Moisture Barrier A visqueen vapor barrier, a· minimum 6 mils thick, should be placed underneath the slab, near the midpoint of the underslab sand layer, in areas where moisture sensitive floor coverings are proposed. This vapor barrier should be lapped adequately to provide a continuous waterproof barrier·under the entire slab. ·Moisture barrier placement beneath the . garage slab is.optional. However, future uses of the garage slab area (room conversion, storage of moisture sensitive material) should be considered. · Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page 17 CONVENTIONAL RETAINING WALLS General The design parameters provided below assume that very low expansive soils (such as Class 2 permeable filter material or Class 3 aggregate base) are used to backfill any retaining walls from the back ofthe heel of the footing. If expansive soils are used to backfill the proposed walls, increased active and at-rest earth pressureswill need to be utilized for retaining wall design, and may be provided upon request. Building ·walls, below grade, should be water-proofed or damp-proofed, depending o·n the degree of moisture protection desired. The foundation system for the proposed conventional retaining walls should be designed in accordance with the recommendations presented in the preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches). There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e., loffel, crib, earthstone, etc.) will differ from those provided below. Recommendations for specialty walls may be provided upon request, or at the time they are reviewed by this office on the draft civil drawings. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pounds per cubic foot (pct), plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 1 o feet high. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Approp.riate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions such as traffic, structures, hydrostatic pressures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads·can be provided upon request. Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rall Road, Carlsbad Flle:e:\wp7\3400\3460a.pge r.oa.Cnllc_ IN..-_ W.O. 3460-A-SC November 27, 2002 Page 18 Level* 40 2 to 1 55 * Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without a slo e for a distance of 2H behind the wall, where H is the hei ht of the wall. Wall Backfill and Drainage The above criteria assumes that very low expansive soils are used as backfill, and that hydrostatic pressures are not allowed to build up·behlnd the wall. Positive drainage must be provided behind all retaining walls in the form of perforated pipe placed within gravel wrapped in geofabric and outlets. A backdrain system Is considered necessary for retaining · walls that are 2 feet or greater in height. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in ·either Class 2 permeable filter material or ½-to ¾-inch gravel wrapped in approved filter fabric (Mirafi' 140 or equivalent). The filter material should extend a minimum of 1 horizontal foot behind the base of the '-"!'alls and upward at least 1 foot. Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no more greater than ± 100 feet apart. The use of weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with relatively impermeable soil. Proper surface drainage should also be provided. Consideration should be given to applying a water-proof membrane to all retaining structures. The LJse · of a waterstop should be considered for all concrete and masonry joints. Top of Slope/Perimeter Walls The geotechnical parameters previously provided may be utilized for free standing sound walls or perimeter walls, which are founded in either competent bedrock or compacted fill materials. The strength of the concrete and grout-should be evaluated .by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The placing of joints (expansion and crack control) should be incorporated into the wall layout. These expansion joints should be placed no greater than 20 feet on-center and should be reviewed by the civil engineer and structural engineer of record. GSI anticipates distortions on the order of½ to ± 1 inch in 50 feet for these walls loeated at the tops of fill/cut slopes. To reduce this potential, the footings may be deepened and/or the use of piers may be considered. · · Footing Excavation Observation All footing excavations for walls and appurtenant structures should be observed by the geotechnical consultant to evaluate the anticipated near surface conditions prior·to the Mr. Wllllam and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad File:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page 19 placement of steel or concrete. Based on the conditions encountered durin·g the observations of the footing excavation, supplemental recommendations may be offered, as appropriate. Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials tor a distance of two times the height of the wall (2H). b) Increase of the amount of reinforcing steel and wall detailing {i.e., expansion joints or crack control joints) such that a angular distortion of 1 /360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be sealed with a flexible, non-shrink grout. c) Embed the footings entirely into native formational material. If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation 11a11 (above) and until such transition is between 45 and 90 degrees to the wall alignment. EXTERIOR FLATWORK Exterior driveways, walkways, sidewalks, or patios; using concrete slab on grade constructior:i should be designed and constructed in accordance with the following criteria: 1. Structural and driveway slabs should be a minimum 4 inches in thickness; all other exterior slabs may be a nominal 4 inches in thickness. A thickened edge (minimum of 12 inches) should be constructed for all flatwork adjacent to landscape areas. 2. Slab . subgrade (i.e., existing ·fill materials) should be compacted to a minimum 90 percent relative compaction and moisture conditioned to at or above the soils . optimum moisture content. This should be verified by this office at least 72 hours prior to pouring concrete. The use of Class 2, Class 3, or decomposed granite (I.e., DG) as a base for the concrete slab in non-Vehicle traffic areas is not required. . . 3. The use of transverse and longitudinal control joints should be considered to help control slab cracking due to concrete shrinkage or expansion. Two of the best ways to control this movement Is: 1) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and/or 2) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. We would suggest that the maximum control joint spacing be placed on 5-to 8-foot centers, or the smallest dimension of the slab, whichever is least. 4. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Mr. William and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad File:e:\wp7\3400\3460a.pge Con.Cnilc_ 'J .. .-_ W.O. 3460-A-SC November 27, 2002 Page 20 5. Positive site drainage should be maintained at all times. Water should not be allowed to pond or seep into the ground. If planters or landscaping are adjacentto paved areas, measures should be taken to minimize the potential for water to enter the pavement section. This may· be accomplished using thickened PCC pavement edges and concrete cut off barriers or deepened curbs, in addition to eliminating granular base · materials (i.e., Class 2, 3, D.G. etc.) underlying the slab. · 6. In areas directly adjacent to a continuous source of moisture (i.e., Irrigation, planters, etc.), all joints should be sealed with flexible mastic. 7. Concrete compression strength should be a minimum of 2,500 psi. RECOMMENDED PAVEMENT SECTION The:-initiaf pavement sections preseoteo . herein are based ori test "R"-value of 73 for typical site materials, traffic indices of 5.0, and the guidelines presented in the latest revision to the California Department of Transportation 'Highway Design Manual" fourth edition. Based on this information, it is likely that pavement sections will be 4.0 inches of AC. on 4.0 inches of Class 2 aggregate base rock (or equivalent). Final pavement designs should be based upon actual "R" -value testing of materials exposed at subgrade elevations at the conclusion of earthwork. DEVELOPMENT CRITERIA Landscape Maintenance and Planting Water has been shown to weaken the inherent strength of soil and slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from graded slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Overwatering should be avoided. Graded slopes constructed wittiin and utilizing onsite materials would be erosive. Eroded debris may be minimized and surficlal slope stability enhanced by establishing and maintaining a· suitable vegetation cover soon after construction .. Plants selected for landscaping should be light weight, deep rooted types which require little water and are capable of surviving the prevailing climate. Compaction to the face of fill slopes would tend to minimize short term erosion until vegetation is established. In order to minimize erosion on a slope face, an erosion control fabric (i.e., jute matting) may be considered. From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils area processed for the purpose of adding amendments they should be recompacted to 90 percent relative compaction. Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November27,2002 Page 21 Additional Site Improvements Recommendations for additionai grading, exterio"r concrete flatwork design and construction, including driveways, can be provided upon request. If in the future, any additional improvements are planned for the site, recommendations concerning the geological or . geotechnical aspects of design and construction of said improvements could be provided upon request. · Trenching All footing trench excavations for structures and walls should be observed and approved by a representative of this office prior to placing reinforcement. Footirig trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum · relative compaction of 90 percent if not removed from the site. All excavations should be observed by one of our representatives and conform to CAL-OSHA and local safety codes. GSI does not consult In the area of safety engineers. · . . In addition, the potential for encountering hard spots during footing and utility trench excavations should be anticipated. If these concretions are encountered within the proposed footing trench, they should be removed, which could produce larger excavated areas within the footing or utility trenches. Drainage Positive site drainage should be maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground. Pad drainage should be directed toward the street or other approved area. Roof gutters and down· spouts should be considered to control roof drainage. Down spouts should outlet a minimum of 5 feet from the proposed structure or into a subsurface drainage system. We would recommend that any . proposed open bottom planters adjacent to proposed structures be eliminated for a minimum distance of 1 O feet. As an alternative, closed bottom type planters could be utilized. An outlet . placed in the bottom of the planter, could be installed to direct drainage awayfroni structures or any exterio'r concrete flatwork. · Utility Trench Backfill 1. All utility trench backfill in structural areas, slopes, and beneath hardscape features should be brought to near optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. Flooding/jetting is not recommended for the site soil materials. As an alternative, imported sandy material with a sand equivalence (S.E.) of 30 or greater, may be flooded/jetted in shallow (±12 inches or less) under-slab interior trenches, only. 2. Sand backfill, unless trench excavation material, should not be allowed in exterior trenches adjacent to and within an area extending below a 1: 1 plane projected from the outside bottom edge of the footing. · · Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad File:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 Page 22 3. All trench exec:ivations should minimally conform to CAL-OSHA and local safety codes. 4. Soils generated from utility trench excavations to be used onsite should be compacted to 90 percent minimum relative compaction. This material must not alter positive drainage patterns that direct drainage away from the structural area and towards the . street. PLAN REVIEW Final project plans should be reviewed by this office prior to construction, so that construction is in accordance with this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. INVESTIGATION LIMITATIONS · Inasmuch as our study is based upon the site materials ob·served, selective laboratory testing and engineering analysis, the conclusions and recommendations are professional opinions.· These opinions have been derived in accordance with current standards of practice, and no warranty Is expressed _or implied. Standards of practice are subject to change with time. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, for our scope-of- work was expressly limited to the evaluation of the sedimen,ts/soils underlying the proposed residence. In addition, this report may be subject to review by the controlling authorities. Mr. WIiiiam and Ms. Candace Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp7\3400\3460a.pge W.O. 3460-A-SC November 27, 2002 · Page23 ·J:,' .... .... . . ~ .. : . \. ·,,:. ·;· .. ·.' .. ::·,·.: ... ·, :,· ... ··,; .. , . ( .-.. ~ '••, -··. ' • t ' •••• : .. ~ ' . : ·, :,.··' ., , -~ •.,.,,I: . '. ·? ·. •:,., ,• ... ' ··':: .-•.·, '' . .' .... · ... ·};. •"1'' ,;-· .. ·.·. :_:. : :·,,:; ., '.: t. ~. ·.-~.·· • : .. .-~ .. ::, .. i '.' .. ,· I. , ,I .• ' . . ~'. . ", :, ~ ·, ·- :,'.-.: .: - . . ~. ,·,.i: ,.:,. .. . .· ,• ...... 1~·: . ,:· .,· ,• .. ·. .', .. ·.:. ·1 .. ,, :!•' .. . ' ." ·: ··.: • : r .• ' ' ~· "'I' ···:, ' ,, ·: .. ,., .· .·.· .. · ... • · ..... ~ '',' \. -~ ·:.'· '·. • .... ', ... •· 1 ' • .: .,·' . •· ··:;., ·,. ,•• .: r: :. • .. ••:c•: •, • ·' .. , ... • •i . ... : ·; •, ~:. : .. ~ ; .·. ... ',: .. . . ~ .. •':, . .-. · ... ··:-:· ,;-. .-. •.1.: :-: ,_:·,·-:. .,-...... '., . .... . ,·. ,,· .· ·: .. , . ·· ... -.. . ,' ,•,I •• •'••.· .. ·, ..... .. . · -,·: .· .. -::' ··:· . ': .. ,, ' ' ·.·, .·_.: ',!• :· ... ,'l •·· :• /, .' •• • .. ~'. r ·: . ':•'' . '\ .. . . ' t : ~ ., .. •'• ~. : ... •·· .... . ....... ·, ' ,,•. . ,', :• 'I ,,_ ·,. . .... :'-: . i ·:: :· . .;.: :'·APPE'NDl)tA: > --~ ·.~·-.-·· .~ .,.··. I,•: ;· .... . . .' : ~ : . ..... '' !'· . !·' • ~ I • ' ·•:· ·:, •, : ·.~· . : -;\ '', •• ~.: I ··.•. t .... '} :.-:· . I· .. -:··, . :: \ . ·. ·.: .: .:. , ... .... ',•; ' ... ' .~ . ' ·: ' •.•.,,. ·.-. ·:· ,~ 1 ,I >•::,, .. ·,.·.' : ·.-' r . : ... .·.· ·. '•, : . . . ·.' .. •.•• l •·; ...... ., ... :· ··. ·. .>.·.: .. ,➔ : .. .-.. . . ·,: -:• ··-.' '·.: . ,, . •. -~- .'f ,.,· ,: ~-' .. •', ,\ . ~ . : ... '.',,.',' . ·• ... . ~ · .. ...... -·~ ·:· .. •' .' :.· -',J • ••• ,', ..... : ~ , , ., . \, •,.• : ··,_: .··,., \ ·,: \ ...... ·,. :· . /",i ,• '·. ·.'·,: ,. ... , · .. • .. · • ~ I • ···,· ••~:• I .-,_J.· •' , •I" ;'. . .' .. , . ' ~ . : . - .. ' ·; ,, ... _.. ·:·. ~ : 1,': .. ... :,,:. . ··. ,· .. .,·•,. '• . •,· .. : : '", . --·:• . -·:·.••",, . : • •• ~'i •• . ~ :. ,•. · ... ' .. ' ···,:,' . 'i . ~ . ' ' . • • ~ • I ·. :. ,. . , .. .. \· ·.· ..._ .. .. . ·_.,_,, .. :·',' ,. . .. ·, ... . •• . ·.,.· . ,•· .. • .. ·:·:· ; .. _ . · .. ;• ,• ... -·. ·;: .... ·., .. ·: ,,••. . : · . : ·~.... . :· : . ~ ., ., .. ·,::- '',•. ,·., :•: . ', : .. :· '·",. ,'j '" 11 I:• ' ·:. ·'· . ~ .... ~--. . . ' ' ·~ ·. ;".· ... .-··,: . ,• . ,• ' . ' ., .. \ ., ·, ' •• ··: + ~ ).··· . .··.-.. '.··, . ~-\ ·. :• APPENDIX A. REFERENCES Blake, Thomas F ., 1997, EQFAULT computer program and users manual for the deterministic prediction of horizontal accelerations from digitized California faults. Campbell, K.W., 1994·, Empirical prediction of ·near-source ground motion from large. earthquakes, in Johnson, J.A., Campbell, K.W., and Blake, eds., T.F., AEG short course, seismic hazard analysis, June 18. · Greensfelder, R.W., 1974, Maximum credible rock acceleration from earthquakes in California: California Division of Mines and Geology, map sheet 23. Hart, E.W. and ·Bryant, W.A.,. 1997, Fault-rupture hazar~ zones in California: California Department of C<;>nservation, Division of Mines .and Geology, special pl)blication 42. Housner, G. W., 1970, Strong ground motion in earthquake engineering, Robert Wiegel, ed., Prentice-Hall. International Conference of Building Officials, 1997, Uniform building code: Whittier, California. Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, m~p sheet no. 6, scale 1 :750,000. Joyner, W.B, and Boore, D.M., 1994a, Estimation of response-spectral values as functions of magnitude, distance and site· conditions, in Johnson, J.A., Campbell, K.W., and Blake, eds., T.F., AEG short course, seismic hazard analysis, June 18. __ , 1994b, Prediction of earthquake response spectra, in Johnson, J.A., Campbell, K.W., · and Blake, eds., T.F., AEG short course, seismic hazard analysis, June 18. Sadigh, K., Egan, J., and Youngs, R., 1989, Predictive ground motion equ~tio_ns reported in Joyner, W.B., and Boore, D.M.·, Measurement, characterization, and prediction of strong ground mo1ion, in earthquake engineering and soil dynamics II, recent advances in ground motion evaluation, Von Thun, J.L., ed.: American society qf civil engineers geotechnical special publication no. 2~, pp: 43-102. Sowers and Sowers, 1970, Un'ified soil classification system (after U. S. waterways experiment station and ASTM 02487-667), in Introductory soil mechanics, New York. Tan, S.S., and Kennedy, Michael P., 1996, Geologic maps of the northwestern part of San Diego County, California: California Division of Mines and Geology, open file report 96-02. · C.on..Cnilc_ fn.-_ I • ,•• =•:· '' -. : "···. '.,•· .·) .. ,t' .. :,' ... ·· .. •,·: .. , ... ,c: ... •:', . ·:·- • ~ I ,..' I'•• .~ • I I . •'· ··: .-._,,;. :•··. ~· ',. .. •:;,· . . \ -~. :•·,: :-: . ·., -:; . : .. · • • i; ~ I ' •: • • ,, ,~.-' ,; . ' .· .. :-· .. '.·· . ,.· .. · ;. \ ,· ·• •• •• w ·. ··. :.·· ''' . •.• ........ . .-: !."' , I. :'"· !-• • I : ..... •:·.= · .. ·. :.·.· ·: •, '. • .• ·.: r•I' ':.:· ·. ~ ,·; i ••• . : ~ . ; ::,· . i: -~. ..... :. ~·· .. -.· .... : .. : . . , . : .. r· ·' ,. ·:: .. . ,.·.,. : .... ·,···: :; . ,_-:. '\,_ .. -: ·, .· :: · .. • .. --,; •:.' .,._ .. _ _. ... . . :• ' ·~ .. \ . ..... , .. • .-·(I ....... · : : ... ;-. ~;.' · .. . :APPEN·D.IX .Et'..• .. .• .•.• •' ' •• ~ ' .. ·, '•,,·, •',. •·:·- . :, ,'.\ .· .-· .. . ·. ~,:. ·. , .... . ' ;' \•• ,•' ,· _1 ,' • _:·· ,,•·· .. : ,: , .. : ,· :·, ,·\ .. .'· ....... ·: ... ·.,· :·.-. :· :, ·. . i~ •', •.' : : . . ~ . : . , ; :_ '• ', . ,. ' ·'· i . ·, ·-. \ f '.; _ .•• :,•. ·.· .. • .. •··' . t . ·,-: . : ' ' . :-. ~ . ~- ••' ._ · ......... · :-.. . : . ;:, ,, ... . 1:: ..... •.,· ···. ·, ,·. -·\. ',': . ' I . : .. ·., .. .. •': . ,. ·. . ·.· :·:· , .. -: ... -~. ,;· ,', ;'1,. .... ,. ·:,.--::·--: ,•• I ·•:" . t : :· .. ·, I t '. . ,• l ,·.-··. ·:,: . ·, , .... '·:-"· .. ,: '( . ~:~ ,· . ::· ... ' .. ·•:· , .. ,' :• -- ••• '•. ,I • ; · .. ' . ~ : . · . .,._. • • I : • ~ . ... ·:·-,., . .. -: .·': ' : ; . I'; ... · .. •,:• ··. '. BORING LOG J GeoSoils, Inc. w.o. 3460-A-SC PROJECT:LYNN BORING 8-1 SHEET~ OE.!_ 6575 Black Rall Road, Carlsbad DATE EXCAVATED 11-11-02 Sample SAMPLE METHOD: HAND AUGER --II Standard Penetrallqn Test --~ '¥. Groun~ater ;I ~'[ e:. C: ~ Undisturbed, Ring Sample e I!! 0 "6 = .i!!i C: --i I!! :5 i ~1 :::> Q. ~ ],£! i:' 0 .a Description of Material a, :::, Ill C ID :>.a iii ::, Cl) 0 :E Cl) ;... SM ."':""'.· ARTIFICIAL FILUUNDOCUMENTED: V,. . . . @ 01-%1 Sl[TY S~!\10, orange 6rown, moist, loose . -~· . . . . SM ."':""'.· TERRACE DEPOSITS: .v-. : .@%'-1' Sl[TY S~I\ID, orange brown, dry, mediurn·dense to dense. -':-"":"' Practical Refusal @ 1' No Groundwater Encountered Backfilled 11-11-02 .-C - -u D 5- D -IJ '" - I'-,., -,~ In IU . C GeoSoils, Inc. In ·6575 Black Rall Road, Carlsbad PLATE B-1 lu BORING LOG GeoSoils, Inc. w.o. 3460-A-SC PROJECT:L YNN BORING . B-2 SHEET_!_ ·oE.!_ 6575 Black Rall Road, Carlsbad DAT£ EXCAVATED . 11-11-02 Sample SAMPLE METHOD: HAND AUGER -m Standard Penetration Test -~ 'Sl.. Groundwater ·~ i!fi" ~ C ~ Undisturbed, Ring Sample I I!! 0 ~~ ~8 = = ' '"O .a I! .!!! a> ::, 0. ~ ., .a a, ::, §~ Cl)[ c:, ~ ftl Description of Material 0 ID ID :>Cl) 0 Cl) SM .'-!"'".' COLLUVIUMITOPSOIL: _ _,..__. ... @0'-1' SILTY SAND, orange brown, moist, loose; roots and ·~-. :0:· rootlets. ,\J""'," .;.,:.,: ·...;-:..·. SM .~.· WEATHERED TERRACE. DEPOSITS: _ _,..__. . . . @ 1 '-2' SILTY SAND, orange brown, dry, loose; porous . ':-I":'', :~:-·'""'·' '':"""':''. ·...;.,;..·. SM .~.-TERRACE DEPOSITS: ·""·" ... @ 2'-3' SILTY SAND, orange brown, dry to moist, medium dense to· ·:,,.,-:-·, ·~-. dense. ,:..,,,,.,· . _,_. ·..;.:.·. Practical Refusal @ 3' No Groundwater Encountered Backfilled 11 -11-02 - 5- - - . - 6575 Black Rail Road, Carlsbad GeoSoils, Inc,· PLATE· B-2 BORING LOG □ GeoSoils, Inc. w.o. 3460-A-SC PROJECT:LYNN BORING 8-3 SHEET_J_ OE_!_ 6575 Black Rall Road, Carlsbad. DATE EXCAVATED 11-11-02 Sample SAMPLE METHOD: HAND AUGER -m Standard Penetration Test -~c-[ ~ "Sl-Groundwater .g C ~ Undisturbed, Ring Sample i :=! 8. 2! :8 :5 ' "C ~i5 c-.a I! .!! G) ::, 0.. ~ -c-e ~1 1::-I .a Description of Material LI G) ::, :§.a IV C m m C rn SM .-..r--.· COLLUVIUM/TOPSOIL: .:.r.· ... @0'-1' SILTY SAND, orange brown, moist, loose; roots and -. ,r.-·. □ :0:• rootlets. ,,:..,,-,,,. '!'-";', ·.,;,,.·. SM . ."'-('.· WEATHERED. TERRACE DEPOSITS: n . '-"'·. . . . @ 11-1%1 SILTY SAND,_orange 6rown, dry, loose . ~-.. J . . . SM ."-!"'.' TERRACE DEPOSITS: . '-"'·. . . . @ 1'-2' SILTY SAND, orange brown, dry, medium dense to dense .. ·~·. D ... Practical Refusal @ 2' No Groundwater Encountered Backfilled 11-11-02 -D . D 0 5· □ -D -D -I . - 6575 Black Rall Road, Carlsbad GeoSoils, Inc. PLATE B-3 GeoSoils, Inc. PROJECT:L YNN 6575 Black Rall Road, Carlsbad Sample SM SM SM - 5· - - - 6575 Black Rall Road, Carlsbad BORING LOG BORING B-4 W.O. __ 34----'-60-,'-A'-·..:.S_c_· _ SHEET~ OE..!... DATE EXCAVATED ___ ....__1_1·_11_·0_2 ___ _ SAMPLE METHOD: _H_A_N_D_A_U_G_ER ________________ _ ffl Standard PenetraUon Test ~ Undisturbed, Ring Sample :l-Groundwater Description of Material :~:: COLLUVIUM/TOPSOIL: .;,:..: @0'-1' SILTY SAND, orange brown, moist, loose; roots and rootlets . :0:· • V"'-.· ., ·~·. ·..;,,:..·. :~:: WEATHERED TERRACE DEPOSITS: .;,:.,: @ 1'-2' SILTY SAND, orange brown, dry to moist, loose. :0:-.:.r .. -~--·..;,.·. .--r-.· -~-· ':,,>"';'', ,..,-.,· ':--"':"', ..,,. . . '<"' .. -~-: ·,.;,,:-·. :~:--~.· ·.....:-· . . ·-· TERRACE DEPOSITS: @ 2'-4' SILTY SAND, orange brown, moist, medium dense. Total Depth = 4' No Groundwater Encountered Backfilled 11-11-02 GeoSoils, Inc. PLATE B-4 BORING LOG ' D GeoSoils, Inc. w.o. 3460-A-SC ~ PROJECT:L YNN BORING 8-5 SHEET_!_ 0~ 6575 Black Rall Road, Carlsbad DATE EXCAVATED 11-11-02 J Sample SAMPLE METHOD: HAND AUGER l!I Standard Penetration Test D ~[ §:· ~ 'Sl. Groundwater ~ C ~ Undisturbed, Ring Sample 1 I!! :8 = l!al ~:& c-~ e n ::, c.. ~ -g,e Cl) [ g 0 .a Description of Material i!l ::, Ill u Ill ::, .a Ill ::, Cl) :E Cl) SM ~-· ARTIFICIAL FILUUNDOCUMENTED: .v-.· @ 0'-3' SILTY SAND, orange brown, moist, loose. ":,,>';'". D :0 :• .......... . ;.,..:..: ·...;,,:.·. -... '-r .. D -~-: ·,.;,,-:-·. ·0:-..,,.. . . ,.,.,.._ -:0:- ID .-r.· ':-"":"', ·..:,,:.·. _,.... -~-: l'7 ·..;:,.• . . . . SM ,"-1".' TERRACE DEPOSITS: u -~:: @3'-4' SILTY SAND, orange brown, moist, medium dense. :¥;''. :0:-,:..,--.· .., :--"':'', ·..:,,:.·. I Total Depth= 4' No Groundwater Encountered Backfilled n-11-02 D 5- IU - ID . 0 -I In I.J - In Ii.... 6575 Black Rall Road, Carlsbad GeoSoils, Inc. In PLATE B-5 IL. GeoSoils, Inc. PROJECT:L YNN 6575 Black Rall Road, Carlsbad Sample - - 5- - - - 6575 Black ·Rall Road, Carlsbad BORING LOG BORING B-6 DATE EXCAVATED w.o. __ 34_s_0-_A_-s_c __ SHEET-1_ OE..!_ 11-11-02 SAMPLE METHOD: _H_A_ND-"-A.;...UG_E_R ______________ _ ffl Standard Penetration Test Sl Groundwater ~ Undisturbed, Ring Sample Description of Material -~-· . '-"·. -~·. COLLUVIUM/TOPSOIL: @0'-1/z' SILTY SAND, orange browri, dry, loose: . . . . . ."'1"".' . '-"·. ':J":"'. WEATHERED TERRACE DEPOSITS: @½1-1' SILTY SAND, orange brown, dry, loose to medium dense; : ~:: TERRACE DEPOSITS: -;...;-: @ 1'-2' SILTY SAND, orange brown, dry to _moist, medium dense to dense; :~:-.~.· .;...:.,: ·..;r..·. Practical Refusal @ 2' No Groundwater Encountered Backfilled on 11-11-02 GeoSoils, Inc. PLATE B-6 •, .·, I, •·• '• •,·· ·1'' ,,•'• . '.' :. .·'··· :: ',. ... · :· •' :-: .i, •' ··· .. : .: .. ::. · .. ': .. : .. · ·.··'· ·•.··· . ·• ... , : ~ • : ·'. 1,. • ,: . ·: '< .... •,• , . '.•· ·• · .. :--~,. ': ', ,' ., .'•.· '•.' •, •'• ., : · ..... ,::::= .. :·•·:,:. . ; ·~· ,·1••··· , . ' .•.,:, ··:, ; ,.,. . ,• ;, ... ,.·. ' ,' .. '•· ..... : . .-:.:·•. · .. ' (; ~. : . _1 :, .-:~ • : .• 1'.: . ... ~ : . ·:· ,:,. . '• . . ~· :··:: . : . :• .... r·. •. ':,_ ·.::.·•; ~., .. ....... :, ... .:.·, .. ... :" ·. ':: ,; . ;-•' ·. ,; ·. ~ ·. . ·• .. ··; .... ,·. . ... •:·, .,: ... ... : i ·.·: : ~ ·• .. ", ·· .. '' ·, ,. . :· . .-' _,.·· . •'•,·. .·. _-:· '.:AP.P·ENO:IX. C. '·~·: ,. . :· •. ·: ·:=. : ·, ' . . ,·.,; .. ::·•, .... . :··EaFAuLt~·-1:aseAR·c~,-~F~1s·~s.P.·,·,-; ... . .: . .-_: ·< i ·. -·:·. ,• .... •,'': I' •',':,, .,_, . : ... '. ' ·.; \ ,·:··· •, ... ·• .-',··· . . . . ·. -~ '• . .} . ·. ',• ·, '• . ' .. . ' . . ,'.; ... . . ,. I. ·:·.-... •\.' .. , ..... . . . ~. ' ' . ' . , ' •• :_ .J_ •• : ·.·. '· ,. •'. .. · :• ·.· .. .• :··. •., ', I . . . • , .. ; ·. ·. ,' .. : . ....... '.'.·. "• . · ·,,·. . : . ':: .. ••., I ,,,; .. ,• .. :' ·.··· . , .... , : '• .... -·,• · .. · ,,,,. . ~: ..... ·. ' ' .. . ~ .•. : . '··.-, .. : . "•,·:.· . ,.·,:. .,, I'• .. . ~ . ;·;_.·,:,. . .. , . : \·• '. . ~-. . ~ : . i . . ,',;. .,. ::. . / .... · .. :•·•. ! . • ~ . '· .. , . . . ;_, .• ,,. .· .• ? •.-·' .... .. ···, .. ·... ' ... . : ~ . _,. '. . . · .. , ,, .. ., :·:::· .· .... . .. · .. · . ..•: .... ,· . : •··.•· .. \,: .. . , . .···· ,: ,: I . ,; ,.:', _.·::. ·. , .. .' . : i . . ~ .... '· .·. • ... ·, .. '· · .. ' i·· ,·'.--. . .. \ ... , .. ~ .. \' .··. r· = ,•.,. :·: •,, ... I,:: . _;,:· .. •',· '11 ~-c ... CD 0 I .... COMPARISON OF MAXIMUM EARTHQUAK.ES MAXIM.UM CREDIBLE EARTHQUAKES MAXIMUM PROBABLE EARTHQUAKES 2 ,---... ..---.. CJ\ 1 CJ\ '-" ..._, • z • X z 0 0 ~ • X ~ ·r X 0::: 0:: w X w 21 _J 1 X _) X w X X w X u u u 0.1 X u 0.1 X <{ • X: <{ • _J • x><s< _) 6 X X <{ ~ X ~ I-' • ~ • xx z j z 0 0 X X,.X X N N X:11: 1 2 ?-'#.x 0:: ~ 0:: 0 0 X I 0.01 X I 0.01 xx ~ ::::s:: • ::::s:: • X ~ • <{ • 1 w a.. • a.. • Xx 0.001 0.1 10 100 1000 0.001 0.1 10 100 1000 -DISTANCE (mi) DISTANCE (mi) JOB NO.: 346O-A-SC LATITUDE: 33.1122 N -LONGITUDE: 117.2879 W .,......_ z '---' n:: ~ >- ........... (/) I-z w GJ LL 0 n:: w (I) ~ :::> z w > ~ :::::) ~ :::::) u LYN N LOG N -3.558 -0.746M 1 00 .------.----.--..-----.----.--,-----.----.--..----,----.---, 10 0.1 0.01 0.001 0.00013.0 4 .0 5.0 6.0 MAGNITUDE (M) + 7.0 8.0 SE ISMIC RECURRENCE CUR VE HISTORICAL EARTHQUAKES FROM 1800 TO 2001 9.0 Figure C-2 I \CALIFORN_IA NEVADA\ - ~ ~v~ SAN 01~0 6 PACIFIC OCEAN 6 ~ \ ;( 0 50 100 SCALE (Miles) EXPLANATION C) M = 8.0 + C) M = 7.0-7.9 C) M = 6.0-6.9 6 M = 5.0-5.9 X M = 4.0-4.9 SITE LOCATION ( + ): ~ I JOB NO.: 3460-A-SC ( ~ I Latit~de -33.1 122 N ; ~ ""-D . Longitude -117 .2879 W HISTORICAL EARTHQUAKES 1800 TO 2001 0 I W ~ ___ .:...__ ___________ __.: ___ _j_ ______ _J ~ cc· C ~ ~ 0 I ,........._ ~ w u z <{ 0 w w u X w LL 0 >-I- _J m <{ m 0 er:: (L. PROBABILITY OF EXCEEDANCE vs. ACCELERATION 100 Y1 1111 111111111 111111111 1111111111 ;111111111 111111111 111111111 111 11 11111 111111111 111111111 1111111111 1111111111 1111111111 111111111 111111111 \ - 90 I ' -\ - 80 70 60 50 40 30 20 10 -\ \ \ - , ,\ -- \ -\\ - -\ \ \ \ - ,... \ \ \ \ - -\\ \\ - -\ l~ ~ - -~ ~ ~ -~ ~ 111111111 111111111 111111111 111111111 1111 II 111111111 1111111111 111111111 I 111111111 llllllllll .1111111 11 II 111111 11 8.o 0.1 0.2 o.3 0.4 o.s o.5 o.7 o.8 o.9 1.0 1.1 1.2 1.3 1.4 1.5 ACCELERATION (g) EXPOSURE PERIODS: CAMP. & BOZ. (1994/1997) SR 25 years 75 years 50 years 100 years JOB No.: 3460-A-SC ~-'---------------------------------------------------------' 'T1 (E C .. Cl) 0 I (JI AVERAG E RETURN PERIOD vs. ACCELERATION 10000000 8 6 4 2 ,,.--..,. (/) 1000000 8 I- 0 6 Q) 4 >, / / / - '--,/ 2 ./ 0 100000 8 0 6 / 0:: 4 w Q_ 2 z 10000 8 -/ / / 0:: 6 / =:) 4 / I-2 w 0:: 1000 8 / / w 6 (.'.) 4 <C 2 0:: w 1008 ~ 6 4 / / /. a / 2 108 -I 6 ~; 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 ACCELERATION ( g) LYNN PROPERTY CAMP. & BOZ . (1994/1997) SR JOB No.: 3460-A-SC .· .. _. :.•. ·· .. ··. •·' ', : .. ~-: :-. '·.· •~:., !, I .... _ r,• ••· '•. ·:,: :·, . · .. ·, ,: . . ... , . •.':··· · .. ····: . ~ : .• . . •.•· . ·,,·•, ·:.:.'. ·: ·. ~ ,) ... . ' ... ... . '• ... . ·.·.:. . ,· >' ... ... :,•,· ::_. .•• .. ·. •:-~ ·,\:' .·, .:·. ·.: . ,: :· . ,·· .. . __ ,,., '· ... ~ . ~-' ' ~ ·;--_.·•·· ··· .. . '. ..... ·: .. · .. .. ·, .. >· :, .. t •', .,:·• ,')··' . '· . ~ . •.:.-·•.: _, .. _,..__·. '•• " ' '" \.·."I ':;' ·.: .. •:;; ,\. ·<\:; ... : : . ~ . ,· ............ :::·.~-.·· .. .. , ' ·:. ' . ~ ..•: ,:· ·· .. ·:,:· .. · .,' . :·:•··' ,, ; . •'; . ··•, . . .... . :. ', .. · . : , . ·.:-' ·_1' ::·: . ;·,: : . ' ,•· .; . .. --.·:, :· · . .. , .. ·. . • .. "·•· ..... ,. _:-, . . ·1·,-,.: ·.: . .-:., ... ', .. ·: •·. . ' . ···:.- . . . .. . ~. . .. : ',. ·-·· ,•· .. : ~> •• _. '.· ··'•.:.· -~ . . . :, •, •' ;· .. · . ,'· .· i .: ·.--·. ·. . ":·· ... .. ·· .. ,, t >·1' . . _--: ... ; .. ~. :, ,,\ .. ,', i . ., ·. ·.•· \•' :. ::•. \.• . ·-. .:· ,•.,:. ::•··· .. . !-, ... '· . ,•· ._.; ,·,·· . ',.·. ',• . '· . ' . . . . ' ,-.... ·. ' : . . . ' . . ~ .-:r: .. ' I ~ '• , . / ...... . •:;' ' . ·.: . . ,.,; . ·: '; •'' . . . ~ ' ... .. ·:.-. _: ., . . .. : .. · '"•.·.· I '';, .. .. •· ··. ,, ··. ,., . ~ . ' :-::• ·:. ,.;;_. . -~.' ·-·· · . •. I .• .,,·. .• ... :•. •' I I • •. . ~· ~ . .I,. -~· . : . . .' ', :_ ·~ . \ . . .. 1,. ·•. '. ,: <· ,\ : ·: . , ... ·.•. ·.'\· ,. . .. . ' . . . ; .. ,. ·i. . ' ~-. ;,_ ... ., ., ., .. . .. :,. ·., ·.:· •·, .. •',· ·._., .. ·' ,··. :~' ,·• . . :· .. ' .. ', '•.,,'' . '·. . •:· --~ :' . : ... . .. '~--: .. .. ~ ·~ ', . . ·-:·· ' ., '! ·, ·.• ... ' ' .: ... I •'.''• .:· :; ,' ! .. ;.·1,. .. ' . .,. ·• .. '·' · .... .'·-.. • a' •:• . . . ,•,. ' -~: ·•. ;.· :;;1 . ·,: t._ ;,, . ... ·.:. 3,000 :, ' 2,500 .. 2,000 l V l z ·..,,,, w 1,500 ~ . .. . . V . ! / :c en I 1,000 / / 500 / / .. 0 .. 0 500 . 1,000 1,500 2,000 . 2,500 3,000 .. . . NORMAL PRESSURE, psf S~mple Depth/El. Primary/Residual Shear Sample Type 'Ycs MC% C • • B-1 0.0 Primary Shear Remolded 118.3 9.0 162 29 f ■ B-1 0.0 Residual Shear Remolded 118.3 9.0 155 · 29 € : ! E Note: Sample IMundated prior to testing· ' GeoSolls,-Inc. DIRECT SHEAR TEST I 5741 PalmerWay 1 Project: LYNN c8St-Carlsbad, CA 92008 . t. Number: 3460-A-SC . Telephone: (760) 438-3155 F~: (760) 931-0~15 Date: November 2002 Figure: D -1 ~ . . ._•. .. · ·-'.··· ... ;, ,. . . . .:•. . . .~ , ... _1. ;-· ·• ,. ' • •.:,: • I • • •, -• •,"•, ... : ... ·, .. '·"·' •,• .. •, . , ... :', :: :, :.:. : ... '.-........ ·:, ·_.·/ ·. .·t ,, . t . ··t ., . •,. ,• ,· :.· .. ·.: ·. ·:•.; · .. · .. · \•' . '-:· :-. ,•. ..... ·. .. ' .. ~ ., · .. .. ; .·.···1., . ~ .. ' , .. ·.:.: . . ,,. .. : . -.",. ' .. ., _ _.,: ,:_' ·,:•, ; ~ -: . . •·:· :,\ .. . '-.:,.· 1,; ,'. ·', .. •, . :· . ., .·· . ···. •, -'• . : '·. .•~ .. :::,,: ·.: · .. ··• . ,,· ·.:· ·:: .... '. . •·. . . ·_,;. ,::· .. · ... .'•. : . ;-. : . "•'l • •.,·• .. :···· : r . : :···; .. '· ·,:· .:, . ', ;,' ' : . . ~ : •., ,::, .. ; . '· ~--,··· :. ... ; .:·· . ·. ,, . :·: . . ':·.-. .. , •, :·· . , . \, .. .'.i, · .. -;•, . : f • • ·:· . .-· .. _: .. . ·· .. •. ·~· ., ... •:. ·, I••• ••; .. ·.· '• .. .··, ·: ,' .' I • • ', '.", • ~ ... .. . :,• . "i. :. -· ..... \ .. ' .. ' ~ ' . :·•.•··: .. : .. . ·.: .... -. : .. ' .. .. :·. ·.: ;. ... ~ . ; . , · . ,••: •,· '•. . . · ":. . ' ; .. : . . : . ... . · .. '.• ..... · .. ·:·•,· . 1 •-· • ...... ·. ·,. \ '. :• .. .. ,_.; '•· .. . . .. ··· • i .. . : ' .. ".'·· ·•· . . :. ·:•:· ... ' .•· .. ',A:' . ; ' . ' ·~ , . .-; . .. > .. .... '· ,'t : • ' •• ! •, ' ~:•,I • 1·• . . ~ .. : ..·., ;, ·,·. . .. , . ·: i, • :.~ • I .·,t ' .. :, ... -. •', , ' ... , . .= .. ' ' .. : :. -•.. : .·, · :.: ·:! . r .A· 'p .. ~. p' :E ... _,N-....· ·o-:: 1· )(·.-• .. · :E· ·. · ·_.. ·' · ~ -.. : : ; ... : · · ~ ·_.:: •...• ; ;. •. 1: . • • . . GiiJ~R,ti~~TH\ft/d~kJ~ND G~ADING ~~iciEJ,~~ .• _i •• • :_-· .' • ·:·:.. : • • ' • ~ ·,,_. • • • • • ... • • • : • • • • • ~ •' • • '· ~; . ,•,:.,·. . · .. .. ..... 'I-•,, .. • 1'• .' ·•·:... .· .. . ,:· _._., . ·.• ,•, • ',,., I •, ·,: . ,, I I J'• • •. -~ ' .. ~. .... ,. ··: •.: .. ., . • ••• i, ·: ., . .,,:.-._ . '·: ' .. . ....... ·., :• ·· . ,:-.· ·. ·\ .. . ·: ··:. '• . . ~·:.·· ·, . : · . : :·' . . , I ',1 0 ··., '. '··/:.,-:• '. -t,;. • .. · .. ·,. .. •, ·'. ·:· ·. ·: . ' ,':'-' . : i' . . :· /' ... : . ·· ... , •.·· .. ·. •'; ' . ",. . ; .. ; '. : ~ . ,.; . ; ' . t ··~ _!',_ .-•' .. · .. . . : ... : . . . . .-~ . ... · . . .. -: . '1 • •• ,:·.:. ·:. :. .... _-::· ... ,:· .. '. ·( . -: . -:· ... : •' , .. · . ·'I.,. .. \ . · .. ,-.:. ·:·,. . ·,·: -_. . :._:' :-'1•,:· •.;• · .. , \. •: .. ·• . .. ,: I• ,\ ., • I ••, '··''. . : •. . ..... .'~-: ' . ; ·: · .. -~ ·.' ·. ~ -.. · .. •\,. ·•: ,. •;.•"•', . . .. '"'i i: ••• ··• .. -· . .,_,•' ·._ ...... . ,,' , . . -: ·,·· ·,: ·-·· . .' ,,,.. ..... . -.·. · ... ·· · ..... ~·: ! .. ~. . . . . .. . ~ . ~--. : ... . ~ •, • ·:-:-·, .... 1 ... . ·(. ~ .. _,:; / ..... •.;-.. ::., ! •·. ·•---:·,. -·:.,. -~ . ... .. .. . . :··. ... \ .. ' ,· ~ . -.:··· ,.·. .... .·,: .·\· . ''· ,· ... · .. . ~ . ' . .. . _.:. ':: . I ;. ' .. . . ' ·: .. • 1 • .• .... .. ··.:·•. · .. ' . . . . ~ '. . • ,'I' • ·.,. ;. . .... _, ... ---~. _: ,. ....... . ~ :-_.• . . ...... . · .. : _., .:·,; .. ··-:->. ,' ·. ._!; :·• . ':' . • •. • · .. ·:. .::->' ·::. ;··:.'·' '":.• ' . ..... ·._, .. .-1 •' J ',. -.. ' . : . :·_.' . ; . . -. ' . '.,•:· ... '• ,,• , ... :,• .. ' . . _,. ,•' . .. · . ·· .. ·. ··.'..: .. . ,. .. ' . . ··•. .... . :-· ,"• ,:,: .. ; .. ... -.".' .. ..... :.: .. , ... ,: . ., ··', ~.· . ... :. '•·.· .. .-... : ... -. .. ' .. .... .,·it ,: . ··· .. · . ,. ·.' ·· .. ' ' -~---.... ; . I ,••, .. ·.: ';' ,' ;: ... .'-'<_:.- I • ~ ' .. : '' . ,' : ··.' ·r.:.•,, .' . / · .. •.,,' ::·, \·: .. ~:-.. -. ••• •J ',.' '•.:: .... __ . ~ ... ·.··.··, . •.; .. : • .. :·• : •. .. =.;. /., .. ···-.·· .: .; . .. ,' I, :.:-. ' · . • .. . •,. .: •' , .. .·, . .. . .: ... -~. \ .' .. • . . .. -. /•;' ~· .... ' ~ . . . ' ., '. ,· ·: . \ .· ..... .•, . ._. ... GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to filled, placement of fill, installation of subdrains and excavations. The recommendations contained in the ge·otechnlcal report are part of the earthwork and grading guidelines and would supersede the provisions contained hereaft~r in the case of conflict. Evaluations .performed by the consultant during the course of grading may result in new recommendations which could supersede these guidelines or the recommendations contained in the geotechnical report; The contractor is responsible for the satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications. The project soil engineer and engineering geologist (geotechnical consultant) or their representatives·should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnlcal Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) ·should be employed for the purpose of observing earthwork procedures and testing the fills .for conformance with the recommendations of the geotechnical report, the approved grading plans, and applicable grading codes· and ordinances. The geotechnical consultant should provide testing and observation so that determination may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule the_ir personnel accord_ingly. · All clean-outs,· prepared ground to receive fill, key excavations, and subdrains should be observed and documented by the project engineering geologist and/or soil engineer prior to placing and fill. It is the contractors's responsibility to notify the engineering geologist and soil engin·eer when such areas are ready for observation. Laboratory and Field Tests . . Maximum dry density tests to determine the degree of compaction should be performed in accordance with American Standard Testing Materials test method ASTM designation 0-·. 1557-78. Random field compaction tests should be performed in accordance with test method ASTM designation 0-1556-82, 0-2937 or 0-2922 ·and 0-3017, at intervals of approximately 2 feet of fill height or every 100 cubic yards of fill placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. · ~oSoil.c. lne. Contractor's Responslblllty All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by geotechnical consultants and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the soil engineer, and to place, spread, moisture condition, mix and compact the fill In accordance with the recommendations of the soil engineer. The contractor should also remove all major non-earth material considered unsatisfactory by the soil engineer. · It is the sole responsibility of the contractor to provide adequate equipment and methods . to accomplish the earthwork hi accordance with applicable grading guidelines, codes or agency ordinances, and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion ofthe.geotechnlcal consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock;-'or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary; stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent ~rosion of graded areas until such time as permanent drainage and erosion control measures hav~ been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material should be removed and disposed of off-site. These removals must be concluded prior to placing fill. Existing fill, soil, alluvium, colluvium, or rock materials determined by the soil engineer or engineering geologist as being unsuitable In-place should be removed prior to fill placement. Dep·ending upon the soil conditions, these materials may be reused as compacted fill$. Any materials incorporated as part of the compacted fills should be approved by the soil engineer. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other structures riot located prior to grading are to be removed or treated in a manner recommended by the soil engineer. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground extending to such a depth that surface processing cannot ·adequately improve the condition should be qverexcavated down to .firm grounc:t ·and approved by the soil engineer before compaction and filling operations continue .. Ovetexcavated and processed soils which have been properly mixed and moisture conditioned should be re-compacted to the minimum relative compaction as specified In these guidelines. · Mr. WIiiiam and Ms. Candace Lynn Flle:e:\wp7\3400\3460a.pge Appendix E Page2 Existing ground which is determined to be satisfactory for support of the fills should be scarified to a minimum depth of 6 inches or as directed by the soil engineer. After the scarified ground is brought to optimum moisture content or greater and mixed, the.materials should be compacted as specified herein. If the scarified zone is grater that 6 inches in depth, it may be· necessary to remove the excess and place the material in lifts restricted to about 6 inches in compacted thickness. Existing ground which Is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report or by the on-site soils engineer and/or engineering geologist. Scarification, disc harrowing, or other acceptable form of mixing should continue until the soils are broken down and free of large lumps or clods, until the working surface is reasonably uniform and free from ruts, hollow, hummocks, or other uneven features which would inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 5: 1 (horizon,al to vertical), the ground should be stepped or benched. The lowest bench, which will act as a key, should be a minimum of 15 feet wide and should be at least 2 feet deep into firm material, and approved by the soil engineer and/or engineering geologist. In fill over cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet with the key founded on firm material, as designated by the Geotechnical Consultant. As a general rule, unless specifically recommended otherwise by ·the Soil Engineer, the minimum width of fill keys should be approximately equal to ½ the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove' unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toe of fill benches should be observed and approved by the soil engine~r and/or engineering geologist prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been determined to be suitable by the soil engineer. These materials should be free of roots, tree branches, other organic matter or other deleterious materials. All unsuitable materials should be removed from the fill as directed by the soil engineer. Soils of poor gradation, undesirable expansion potential, or substandard strength characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other bedrock derived material. Benching operations should not result Mr. WIiiiam and Ms. Candace Lynn Flle:e:\wp7\3400\3460a.pge GeoSoils. lne. AppendixE Page3 in the benched material being placed only within a single equipment width away from the fill/bedrock contact. · Oversized materials defined as rock or other irreducible materials with a maximum dimension greater than 12 inches should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the soil engineer. Oversized material should be taken off-site or placed in accordance with recommendations of the soil engineer in areas designated as suitable for rock disposal. Oversized material . ' should not be placed within 1 o feet vertically of finish grade (elevation) or within 20 feet horizontally of slope faces. To facilitate future trenching, rock should not be placed within the range of foundation excavations, future utilities, or underground construction unless specifically approved by the soil engineer and/or the developers representative. If import material Is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the soil engineer to determine its physical properties. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the soil engineer as soon as possible.· Approved fill material should be placed in areas prepared to receive fill in near horizontal layers that when compacted should not exceed 6 inches in thickness. The soil engineer may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each ·1ayer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optimum should be watered and mixed, and wet fill layers should be aerated by scarification or should be blended with drier material. Moisture condition, blending, and mixing of .the fill layer should continue until the fill materials have· a uniform mbisture content at or above optimum moisture. . . After each layer has been evenly spread, moisture conditioned and mixed, it should be .uniformly compacted to a minimum of 90 percent of maximum density as determined by ASTM test"designation, D-1557~78, or as otherwise recommended by the soil engineer. Compaction· equipment should be adequately sized and should be specifically designed for soil compaction or of proven reliability to efficiently achieve the specified degree of compaction. Mr. WIiiiam and Ms. Candace Lynn Rle:e:\wp7\3400\3460a.pge Appendix E Page4 Where tests indicate that the density of any layer of fill, or portion thereof,· is below the required relative compaction, or improper moisture Is in evidence, the particula·r layer or portion shall be re-worked until the required density and/or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has be.en tested and found to meet the density and moisture requirements, and is approved by the soil engineer. Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compactiqn in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. A final determination offill slope compaction should be based on observation and/or testing of the finished slope face. Where compacted fill slopes are designed steeper than 2: 1 (horizontal to vertical), specific material types, a higher minimum relative compaction, and special grading procedures, may be recommended.· · If an alternative to over-building arid cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 1 o feet of each lift of fill by undertaking the following: 1 . · An extra piece of equipment consisting of a heavy short shanked sheepsfoot should be used to roll (horizontal) ·parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the slopes, and extend out over the slope to provide adequate compaction to the face of the slope. 2. Loose fill should not be spilled out over the. face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re-rolling: 3. Field compaction tests will be made in the outer (horizontal) 2 to 8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. · After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to verify compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to confirm compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix and re-compact the slope material as necessary to achieve compaction. Additional testing should be performed to verity·compaction. Mr. WIiiiam and Ms .. Candace Lynn Flle:e:\wp7\3400\3460a.pge GeoSoils. Inc. Appendix E Pages 6. Erosion control and drainage devices should be designed by the project civil engineer in compliance with ordinances of the controlling governmental agencies, and/or in accordance with the recommendation of the soil engineer or engineering geologist. · SUBDRAIN INSTALLATION Subdrains should be Installed in approved ground in accordance with the approximate alignment and details Indicated by the geotechnlcal consultant. Subdrain locations or materials should not be changed or modified without approva.1 of the geotechnlcal consultant. The soil engineer and/or engineering geologist may recommend and direct changes in subdrain line; grade and drain material in the field, pending exposed conditions. The location of constructed subdrains should be recorded by the project civil engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the engineering geologist. If directed by the engineering geologist, further excavations or overexcavation and re-filling of cut areas should be performed and/or remedial grading of cut slopes should be performed; When fill over cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the engineering geologist prior to placement of materials for construction of the fill portion of the slope. The .engineering geologist should observe all cut slopes and should be notified by the contractor when cut slopes are started. If, during the course of grading, unforeseen adverse or potential adverse geologic conditions are encountered, the engineering geologist and soil engineer should investigate, evaluate and make recommendations to treat these problems. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by the engineering geologii;;t, whether anticipated or not.· · Unless otherwise specified In . soil and geological reports, no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractors responsibility. Erosion control and drainage devices should be designed by the project civil engineer and should be constructed iri compliance with the ordinances of the controlling ·governmental agencies, and/or in -accordance with the recommendations of the soil engineer or engineering geologist. Mr. WIiiiam and Ms. Candace Lynn Flle:e:\wp7\3400\3460a.pge GeoSoils. In~. AppendixE Page~ COMPLETION Observation, testing and consultation by the geotechnical consultant should be conducted during the grading operations in order to state an opinion that all cut and filled areas are graded in accordance with the approved project specifications. After completion of grading and after· the soil engineer and engineering geologist have finished their observations of the work, final reports should be submitted subject to review by the controlling governmental agencies. No further excavation or filling should be undertaken without prior notification of the soil engineer and/or engineering geologist. All finished cut and fill slopes should be protected from erosion and/or be planted in accordance with the project specifications and/or as recommended by a landscape architect. Such protection and/or planning should be undertaken as soon as practical after completion of grading. JOB SAFETY General At GeoSoils, Inc. (GSI) getting the job done safely is of primary concern. The following is the company's safety considerations for use by all employees on multi-employer construction sites. On ground personnel are at highest risk of injury and possible fatality on· grading and construction projects.-GSI recognizes that construction activities will vary on each site and that site safety is the prime responsibility of the contractor; how.ever, everyone must be safety conscious and responsible at all time~. To achieve. our goal of avoiding accidents, cooperation between the client, the contractor and GSI personnel must be maintaine.d. · In. an effort to minimize· risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety of field personnel on grading and . construction projects: Safety Meetings: GSI field personnel are directed to attend contractors regularly · scheduled and documented safety meetings. Safety Vests: Safety vests are provided for and are to be worn by GSI personnel at all times when they are working in the field. Safety Flags: Two safety flags are provided to· GSI field technicians; one is to be affixed to the vehicle when on site, the other Is to be placed atop the spoil pile on all test pits. · Mr. Wllllam and Ms; Candace Lynn File:e:\wp7\3400\3460a.pge GeoSoils. lne. Appendix E Page7 .. Flashing Lights: All vehicles-stationary in the grading area shall use rotating or flashing amber beacon, or strobe lights, on the vehicle during all field testing. While operating _a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. · Test Pits Location, Orientation and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technicians's safety. Efforts will be made to coordinate locations with ,he grading contractors authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of current traffic. The contractors authorized representative (dump man, operator, supervisor, grade checker, etc.) should d_irect excavation of the pit and safety during the test period. Of paramount concern should be the soil technicians safety and obtaining enough tests to represent the fill. · Test pits should be excavated so that the spoil pile is placed away form oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment · should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. Thi~ zone is established for safety and to avoid excessive ground vibration which typically decreased test results. When taking slope tests the technician should park the vehicle directly above or.below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively-keep ~II equipment at a-safe operation distance (e.g., 50 feet) away from the slope during this testing.- The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible· location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads; cut and fill areas or other factors that may affect site access and site safety. In the event that the technicians safety is jeopardized or compromised as a result of the contractors failure to comply with any of the above, the technician is required; by company policy, to immediately withdraw and notify his/her supervisor. The grading contractors representative will eventually be contacted in an effort to effect a solution. However, In the interim, no further testing will be performed until the situation is rectified. Any fill pl~ce can be considered unacceptable and subject to reprocessing, recompaction or removal. Mr. WIiiiam and Ms. Candace Lynn Flle:e:\wp7\3400\3460a.pge GeoSoib. lne. AppendixE Pages In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor brings this to his/her attention and notify this office. Effective communication and coordination between the contractors representative and the soils technician is strongly encouraged in order to implement the above safety plan. Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of instability, has any loose rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters, should be shored or laid back. · Trench access should be provided in accordance with CAL-OSHA and/or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down11 on the equipment. · If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires. that the soil technician . withdraw and notify his/her supervisor. The contractors representative will eventually be contacted in an effort to effect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice· · to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify CAL-OSHA and/or the proper authorities. Mr. WIiiiam and Ms. Candace Lynn File:e:\wp7\3400\3460a.pge GeoSoils. lne. AppendixE Page9 FILL OVER NATURAL DETAIL SIDEHILL FILL COMPACTED FILL MAINTAIN MINIMUM ts• WIDTH TOE OF SLOPE AS SHOWN ON GRADING PLAN PROVIDE A t:t MINIMUM PROJECTION FROM DESIGN TOE OF SLOPE TO TOE OF KEY AS SHOWN ON AS BUILT NATURAL SLOPE TO BE RESTORED WITH ~- BENC ... WIDTH MAY VARY ...... ..., I ]~: MINIM~M 7J r )> --'.i m m- G1 . I Ol NOTE: 1, WHERE THE NAiURAL, SLOPE APPROACHES OR EXCEEOS THE 15' MINIMUM KEY WIDTM DESIGN SLOPE RATIO, SPECIAL RECOMMENDATIONS WOULD BE 2'X 3' MINIMUM KEY DEPTH · 2' MINIMUM IN BEDROCK OR APPROVED MATERIAL I PROVIDED BY THE SOILS ENOINEE~. 2. THE NEED FOR AND DISPOSl110N OF DRAINS WOULD BE DETERMINE[ BY THE SOILS ENGINEER BASED UPON EXPOSED CONDITIONS. H FILL OVER CUT □ET AIL CUT/FILL CONTACT 1-. AS SHOWN ·ON GRADING PLAN 2. AS SHOWN ON AS· BUILT ORIGINAL TOPOGRAPHY "'''' f MAINTAIN MINIMUM .15'FILL SECTION FROM BACKCUT TO FACE OF FINISH SLOPE ~-------- BENCH WIDTH MAY-VARY r~, //~~ BEDROCK OR APPROVED MATERIAL LOWEST BENCH WIDTH 1S'MINIMUM OR H/2 -u r )> -, m m G) I "-l NOTE: THE CUT PORTION OF THE SLOPE SHOULD BE EXCAVATED AND EVALUATED BY THE .SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST PRIOR TO CONSTRUCTING THE FILL PORTION. TRANSITION LOT □ET AIL CUT LOT (MATERIAL TYPE TRA~SITION) ---------- PAD GRADE COMPACTED FILL TYPICAL BENCH ING CUT-FILL LOT (DA YUGHT TRANSITION) PAD GRADE NOTE: * DEEPER OVEREXCAVATION MAY BE RECOMMENDED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST IN STEEP CUT-FILL TRANSITION AREAS. PLATE EG-11" .. , -- TEST PIT ·SAFETY DIAGR.A}~ 50 FEET FLA:)_ . SPOIL PILE· SIDE ViEW ( NOT TO SCALE ) TOP VEW 100 FEET ~ . t-ut . u. a an ....... APPROXUo4A TE CENlER / · m FLAG Cl=' TEST·PfT 0 u, 1 • l NOT TO SCALE ) SD FEET -. - I 1 .. · I I PLATE EG-16 ' ' . -Geotechnical • Geologic • Environ.mental . 5741 Palmer Way • Carlsbad, C~lifornia 92008 .~ ·. (760) 438-3155· •. FAX (760) 931-0915 December 20; 2002 · · .. W.0 .. 3460-A1-SC. Mr. WIiiiam· and Ms. Candace Lynn · . . 6575 Black Rail Road . . Carl~b~d, California 92009 Subject: ·References: Soil Corrosivity Test Results, 6575 Black Rail .Road, City of Carlsbad, San Olego County, CaUf<:>rnia . . ' 1. NPreliminary Geotechnical. Investigation;. 6575 Biack Rall Road, City of ·carlsbad; Sari Dlego·.county, California," W.O'. 3460-A"'.SC, dated November 22, 2002, ~y GeoSoils, Inc; ' 2. MUnlfom, Building Code," Whittler,· Califom1~: Vol. 1, 2, and 3, 1997, by · International Conference of Building Officials. :-: · · · · · Dear Mr. and Ms. Lynn: As previously. discussed in Referehce No. f, GeoSoils, In~ .. (GSI); conducted sampling of near-surface soils on the subject site for corrosivity. · Laboratory test results~ completed by · M.J. Schiff & Asspciates, Inc; (consulting ·corrosion engineers), are provided in the attachment. Unless specifically superseded herein, the conclusions and recommendations contained in the referenced reportby GSI remain pertinent and applicab.le, ·and·shouldbe: appropriately implemented during design and .. cohstruction. . · SUMMARY A typical sample of the site materiai' was analyzed for corrosion/acidity poteritiaL The testing included determination. of soluble sulfates, pH, and saturated resistivity. Results indicate that site .soils are . slightly acidic (pH = 6.5) with respect ·10 acidity and are moderately corrosive to ferrous metals. Moderately corroslve·soils .are considered to be in . the range between 2,000 to 10,000 ohms-cm~ ... . Based upon the soluble sulfate· results of 0;054 percent by weight in soil, the.site soils have · · a negligible corrosion potentlal to concrete · (UBC range for. negligible sulfate exposure · is 0.00 to 0.10 percentage· by weight soluble [S04] .in·· son): .Alternative methods and . ·additional comm~nts may be obtained from a qu~lified corroslo~ ~ngineer. · · . . . . ·. ' . . . : . . . .~ . ' '. . . •' . . .' . ·,-';: . . · ::·· .. :. '• I •:: .· . . · .. ·,. ··, :··· . ·, .•' We appreciate.the opportunity to be of further service. If yo·u should 'have any questions,· ' •• ' . J please do not hesitate to call our office. · ·. · . : Re~pectfully submitted, GeoSolls, Inc. · . ·. BV/JPF/DWS/ki Attachment: Soll Corr~sivity Test Results • ·' 1, Distribution: (4) _Addressee .. : :: . . . : : . . . . ' ' .., I • ' ..... .. . . ,' ' ' : _ He:t;,Jd ~:= . -~k/. David W. Skelly· . . Civil Engineer, ACE 47851 · .. '' ' .. •.· ·· .. • a . ~ . • ,I • • _. Mr. Wllllam and Ms. Candace Lynn . :. ·: · ·: ·. · 6575 Black Rail Road, Carlsbad . . -W.O. 3460-A1-SC . · · . · . December 20, 2002 . :, . ·: · Page 2 · . . . Rle:e:\wp9\3400,~~ .set . . ' ·, ·: : .. GeoSoils; ·Jne • .-· 1 _ _.i•• •: •' ;: • • • • • I • . . . . . . '. _: · -,~1. J. · Schiff & Associates, Inc. Consulting Co"osion Engineers -Since 1959 . -. ·, . ' .. . ' ·J 1308 Monte Vista ~venue,.Suite 6 Upland, CA 91786-8224 Phone: 909/931-1360 Table 1_ ~ Laboratory .Tests on Soil Samples · 1SampleID Resistivity ·· as:-received safurat.ed .PH. · Electrical · Conductivit)' Units . ohm-cm . ohm-cm mS/cm - .Chemical Analyses Cations · calcium ea'-• mg/kg_ magnesium . Ml+ mg/kg sodium ·Na1+ · mg/kg Anions carbonate C032•· mg/kg . bicarbonate· HC031" mg/kg chloride . dt•. mg/kg. sulfate S042• ·mg/kg Other Tes~ ammonium NH41+ mg/kg nitrate N0;1° · mg/kg sulfide s'-· qua) Redox mv. . . Lynn Your#3460-A-SC, !,f.JS&A #02~1f35LAB .. · 14-Nov-02 . .B-1 3,700 2,900 · 65 0.11 12 7 28 ND 79 ND 54 na na na na Electrical conductivity in millisiemens/cm and chemical analysis were made on_a 1:5. soil-to-water extraci. . mg/kg = milligrams per kilogram (parts per million) of dry soil. · · Redox = oxidation~reductiori potential in millivolts ND ~ not detected : . na = ~ot.analyzed . •,\', .. ' ':· . ' • I • • • I . ·,. . :•·. . , . i. •. ·. ,:1- . -': .. ~ . -~ .. . ·. ·/·" · .. •·.: . . ',..., '.'• . ~.: . '. ·, .' ' :•·· .... , f ,· .. · •·' .· .. ,.·. . ·/.: .. : .:.:. . / \ (,; ,, .,··· '' .· .... ·:·- .. '• . .. .. . ,: ,;•' ·., . · ..... -:,.,·• . . ~' ·, . '·,. ': :· .. '··. ·• .... ••, I . ;,•• ··-:.. · .. ·.: : . : ... . .~ :. :'.f : · '. '. . . · .. . ~· ,,•. ·. .. :• , .. •I~• .· .. · ,,:,· •• .. ,·'. 'I. ·, . · . •,.;. .. t · .... ; ·, .. ; ·. •',• ...... ~ ... • .... .. '!, · ... ; ; .. ..... : / .... i. ;•,• . ~: • .. ·.·.:· 1'••·· · .. · . ' .. :·. ,··. ;(. .. •, ., · .. .-.:.• ,.• '·• .. . . -Q~Ari;·N~,.PlA~--R~J;ev.i'->':_ .. ::,_:·<·· . · . .'. · ... '···· -: . :.•:ss1s· a.~ck-~1La0Ao,.eR0Pb~.eo·_:suapiv,1~ioN :.: ·.· .. . .-CIT'{61(cAFitseA6'/sAN' lilEGO ... C'OliNtv; CAUFORN'iA:: .... ·. · ' .. · . ,•·.~ .... · .... '••· ... · ... · ,: ' . ·-~·.' ......... ~ _:, ·.•._:,, .. :····.,):··•::. · .. • .. ·•.·;, ~ ·. ;· :. •·, ... ' . .. .·;-: ,' ·•.,,. :. ·,' • ~ I •\'_, ... . . . . ~ .. FOR · . . . ··t ..... . -0:,.-~fi.·WILLIAM 'LY.NN ' . ·. :· .. . , .: · · .... : '5s1s -eLAci< ~A1i:·adAo:.:-. ·. ':.' :· . ,.: ,CARLSBA~-, CAllFOfit•h~(g2·oc>8.:·:, ..· .. , . , .. ,. ,: ·.:.: ,l'.· ~: : . .. , . :.: . .. . ·,-.·· ... . . . . ' .·: · .. ·. _: ·w:0~·345o~A1~SC· ···.ot_:_TO.B_.· ~.R,_'g~· ~oo'~.i: ~•-;: ;'.:~· :· _ _-:··.· ...... ·.: \, .. ' . . : ;-. . , 'r, . •• .. · ...... . .,•• ... . .. , ·. :,. , . . ~ .,·.· .:·.; .. ·. . : ... · ... :· ,·-: .. .. . '•,• '·• ... I •,, . , .~ . I,,• ~ :. ·. ·.. ' .. :., '. I.· :.· ~ . '· . , .... · .. , .. , :.:. . ': •,, ·._._· ·,::. .. , ' . .. ,.· .. .. -:'. •' ·~ : ,· .. ........ · ... .·.: .... . ~ . . '· . . . . ~ . ., ' . ·· .. • .. ' ,· ·-.,·. . .,. ,··'·· .·,. :,••·. . • .. ~ ,_:· .•··· . ...... '•• ·., ... ' ,' ,•.:, I " .. ... -.. :• Geotechnical • Coastal • Geologic • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 Mr. William Lynn · 6575 Black Rail Road Carlsbad, California 92008 October 8, 2003 W.O. 3460-A1-SC Subject: Grading Plan Review, 6575 Black Rail Road, Proposed Subdivision, City of Carlsbad, San Diego County, California References: 1. "Preliminary Geotechnical Evaluation, 6575 Black Rail Road, Proposed Subdivision, Carlsbad, San Diego County, California," W.O. 3460-A-SC, dated November 27, 2002, by GeoSoils, Inc. 2. "Uniform Building Code," dated 1997, by International Conference of Building Officials. 3. "Grading and Erosion Control Plans For: Lynn Minor Subdivision," Sheets 1 through 5, Project No. MS 01-04, dated September 30, 2002, by MLB Engineering. Dear Mr. Lynn: In accordance with a your request, GeoSoils, Inc. (GSI) has performed a review of the grading and erosion control plans, Sheets 1 through 5 for Lynn minor subdivision, prepared by MLB Engineering (see above References). Unless specifically superceded herein, the conclusions and recommendations contained in the previous report (GSI, 2002) remain pertinent and applicable, and should-be appropriately implemented· during planning, design and construction. · The plans, notes and details reviewed appear to be in general conformance with the recommendations provided by this office and presented in the referenced report by GSI, from a geotechnical viewpoint. Supplemental recommendations are provided in the attached Appendix. The opportunity to be of service is greatly appreciated. If you have any questions, do not hesitate to call our office. ..=:::::::::::::s BEV /JPF/DWS/jh Attachment: Appendix -Supplemental Recommendations Distribution: (4) Addressee Mr. WIiiiam Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a1 .gpr W.O. 3460-A1-SC October 8, 2003 Page2 .. ~- . ' . ' t ', • o :, .'' • I ' ·-=:· •'•. r ~ . t .. j • ~ . ,;• ,',, .. ';. : ' · .. ·•: •. t .. ·.·.·: ' ·.· . . . ... . ' .. · .. ~ . : ... '.~ .. : · .. .. : . -) .. . .. _,. ; ·., ·:•·· · ... :. \. ; ·. ·,·· \, .. ·, ::-: • I . •,• .. . : ... '• ·=·· '.· \•; .,. ,: · .. ~--! . . '\ . :'• :· ~ ,'••; ,!•.,: . ,,t ..... . ·. : .• ... . . ·. . ,.:, · ... • .. .. ~ ·.:·· ... -• .. • · .... . • ..• ·· I,., ·, ·.· -~· . ·,·• ·,:r_•,•· .. .. ,· 1., ... :·· ... • . :.•, ::. ' ·.:,. ', ~,:. ....... ' . . ~-. ·'•,. \ ' .. :·· ... ·. ',':. ·, ... ·• ,• _.:·. .'·/:·. ., .. ·•·:. .,: ', ·.·•· ··. ,' .: •., ,:.•: . ·•, .. ...... . .•: .,· ,,1 •• ·• .:., -· . • 1· ... :· •. \ .. :' ·sfjp·pti:rvi~NTAL R'1fcoM:MENOAt1·0N·$·: ' . ' . . =·, ~.. . ·, •, . . . . •.. . ,·, ··: .. . . ' . . . ' '•·,_. ~. ; . •' ~ ... ' : : • ; r . :. ·.·.· . .... : ', . -~ .. ... .-.. ~ ... ~ ' . ·,· . : ,' • ' • I ~ .. _: ... :. ,\:. . ,,.:, •:.,. ', ~-. \ ·, .. ..··':•· ... ~-f • ' ·· ... · ... : . ,. ·. •, . . . : .. '',I • ' . '. i.:. ,. ·,·,·. .. ·.:;-.: , : .. ~~- ,.:··: • ···••4'' .. ' . ~. . . . . ,•. . . ·.•: .. ···l, . \' ·~· .1 .... .. ·, . . . .. ~ . ··• i .. , . . . . ~- .• ,',• ~; . ,' · •. -:._. . ..::: . ·~ · .. ·I, ;,_.·. . ,: . .. ·.:, ·'~· .. : ,• , .. ·, . ·•: '. '-. ... ·,., ,1 ,: '· ·.:·· . ·:·. .. ··,. .·, .·•. ·•.:, . ;.•,'.' ..• .. ::'•: ~-.... ' ,• .·1 •. ·• •• .• . ··;·· ',.: . ,•, •, ~ ... ·' ... :-.-·· DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be exp~cted to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post- construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep Is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and Is anticipated to potentially affect improvements or structures (i.e., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. • This moven:,ent generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to· deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (p~r the Uniform Building Code and/or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and/or any homeowners association. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-wateririg should be avoided as it can adversely affect site improvements, and cause perched groundwater conditions. Graded slopes constructed utilizing onslte materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hard scape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground. In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of one percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet · from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Erosion Control Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum. distance of 1 o feet. As an alternative, closed- bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters Mr. WIiiiam Lynn Ale:e:\wp9\3400\3460a1 .gpr GeoSoils. lne. Appendix Page2 without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon $Urface improvements (i.e., some trees will have an effect on concrete flatworl< with their extensive root systems). From a geotechnical standpoint leaching is not recommended for·establishin·g landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the· drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or non-erosive devices that will carry the water away from the house. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting_ permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. ~hould perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Site Improvements Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench, and retaining wall backfills. TIie Flooring Tile flooring can .crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade where tile will be Mr. WIiiiam Lynn Flle:e:\wp9\3400\346081 .gpr GeoSoils. lne. Appendix Page3 placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyi crack Isolation membrane (appr~ved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading In the street and parking areas and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reiAforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended atthat time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching Considering the nature of the onsite soils, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be observed by one of our representatives and minimally conform to CAL-OSHA and local safety codes. Utility Trench Backfill 1. All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to verify tt)e desired results. 2. Exterior trenches adjacent to, and within areas extending below a 1 : 1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should Mr. William Lynn Flle:e:\wp9\3400\3460a1 .gpr Geo.Soils. lne. Appendix Page4 not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to verify the desired results. 3. All trench excavations should conform to CAL-OSHA and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass· below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade b!3am in accordance with the recommendations of the structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: • During grading/recertification. • After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. • Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement • During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During slope construction/repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. • When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. · Mr. WIiiiam Lynn Flle:e:\wp9\3400\3460a1 .gpr GeoSoils. lne. Appendix Page.5 OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plan~. PLAN REVIEW Final project plans should be reviewed by this office prior to construction, so that construction is In accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies maybe warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and b_edrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subjectto change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction, or work. performed whe_n GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Mr. WIiiiam Lynn Flle:e:\wp9\3400\3460a1 .gpr GeoSoils. lne. Appendix Page6 . : .· . ;. ·.' ·., .... I ,•:'••,••••• . .. . '~-. :· .:•'· .:'• . .. \ ..... •. . :!. ...... : .;· :, ,, ;., ·. ~ ' .. :,. . ···.· ·.·· .. . . ,·,·. , .. ,: ;:•·· .. •: :·:· ·.•., .. . ''I •' .. .. _,:·· '.. ... ; ,'•:. .... · : .. ·.· ...... -:, ·:. ... ." .... ··. • • • r :. -::. . :.-' .. · ... . ..... · . : . ~' . ••.· . : : . : . ,· .. · ...... .. , . ,.:.~: . . . : ~ .. · .., .. • . .· '':· . .. ,, ·. .. •·:•'. .., ; .... ,1·: • # •• .... ' '• ·.· ·: ·:·'··· ... ·' •·. ' \ . :· ... · : ' ·•.•, !-.:. ·. ,_i,' ·:.·, ·.·. ·-:~: . ..... : •;_ . . ·• ::.•.I" .. . • .... : '· ., ~; · .. .. :• . •·· ,'. •:: ., .... •'• ~ . ··. · .. : .. ,:' ' . ',• ·:• . .. ·: ,., '• ·.· •• I ~-1··1 ····.:, ........ : ,·. •,. ::,•-. ~ . . ' · .. :· . ' . . . )' .,_.\. •' ·\•" .. .· .. ·:~ ,..t ... . ; ·,:· :,:· .. •··:,.:I .. "• :,:· .. •:, • .. : .. .•·,, . ·: .... .J,. _; : ••.'•I ', •• ."; , . •' I "'· '.····· : ;· .,:, .:· .. ...... ,,.J ·. '~ ... ·.:. ~ ' .: .. \ ' . . .-., ... . ~-' : . '"'' .. ·,• .•. .: ~:.:· :' . ., \ ,•: ·,., .. :/:' ~---.:. :-_-.... ·. _.··· .... ' • .. :.,.,. : .. ·, .·:.-~---,:_ ·. : .... • •· • ,.I . /" :, ,· ...... ·:·GEOTECl'.f.NICA:L REYIEW·oF;$TF{UOTURAL -Pii:AN$. _:.._ : . > : .-: .. _.-'_:·PARC'EL 4, 6575 .BLACl<"RAJL RPAtf '_.-.·._·· .. •,.,, ... >·:· ·.-'CARLS"BAD~"SAN DIEG'o·cou.NTV;;CALiFORNIA. ..... ,:),: .·.: .• ' ... :,,, .. , .. . ,._· .. · .. .. • ... -::· .. ' ,• .. ..... : . . .. ' . •. :. :; . :· ' _./ ~: . ,. . . . .. ' , . ', ... : . .. . ... , . . . . ,. -::. . ~ ·. ,• t' ' ~ •• J ' .... · ··:;. < _ _.: ::: : F 6~~--.··:-:· ~ ',' ·· ·: ·_ : .. :::: · ____ :_~-~-: -'w,LUAM--~~N·N-·: -----:-·: · '. • . :: 7, •• ' , . , . '.·' ··, '., : : : ,~ . . ' ·.: :··:. . •,·: '··'•: ... ··: ,. · .. ' .. •, ..... ~ . : . . i.• • .•. :-.. •! ,·. ·:. : . · .. \ . . " ~. \. ·.: .. :' .',·. . • .. ·. ,:· ',' .•., . '. . ~ ~' . . . ... :-.~: ._.-~~;-f.~-a~ct< .. fiAn~-.. R __ <;>Ao:· \ . . · --~AFJLSBAP, :CALI F'C>R'N0~~~2.Q9.8 . .;. . ·· .. ·._.:. :._· .. ··.·. • .. ·-:.· <.-·:_ ;~ .. · f·:: .. ~· · .. ,· .·\-._: ... · . ··:· .. 1 • : .. · . :_ :~ ·,: ·, . .. ; ... .. , •• • • . .:-f .,l •' . ;l• •, ·"' .. · 'J., . W;0.-.3460-Ai~s.c · :~-A~4U$T ="23; 2004 · . ' . \ ' ,, ..... ~ . . ~ . . .. :',. .• .. •. ·. ' : ' ;' : . , ' : . . .• ',• ... _ ... ··, . ' ::··· •,·•: : • . .... .. "<, . ' ~. '' ... ,. •. I',.' -:·. ,•· .. :. -· .. ::·:-:• ;_ •••• 1' =-.;\_· . : ... .. . . : . ~ : :_. . ~: .· .. :.-·,· ... ~ . '. '·. • ..... ·, .. ':,. ., : ·.· ,• •,· •.• ·· ... \:,, :; . : ... ' ... •· .. . . .·,· ·:' .•:, ':: ,,', .... ' . . '•, !,. •••• ' . · .. · ·,, ; . ·. ·,• . ·,. '. . \ . ·.. .. -. I , 1, "• \_._. .. .... ', ·::•··: •,· :, ·. :.' (' :' t •• ' -.... ·.•., .• · •f·.· ·· ... . ·\· .. ·· .. ·. . . . . . . i, ,· • • ,~ ,I '. .... ·· ' ,; . .· .. : .· . •. :,·, . ' • ! ... :•> . '·. :·. . _,.·· . · ... ,. '? ·: ·.·.: : ·,. ~ . . ,.•·•: . :. l, • .... , .. ·,; 1 • • • ': I ~ 1 ' ' _ .. :.: .... • : 1' ,·!.. :" . . ·. ·. ..... '' ,· ~·· .. .. '•, : · .. ' ' .: ', '. ...... -.::· :.11·, ,':• .. , .. ,.; . ... · .. · .. . : · .. ': . .', ·, ••,, ,··' '·, .. ;-~ .. • . , :·-..-• •.:: .. ·_.; .. ', I ~; I •:• ~ . : . ' .. , .. ,:_.:.: ., ,, ._._; ::,, : .. •.· . .. ' ., . ·: .:: '• · . .... ' . '·· ,• ~ ·. :. :.,· ,· ·.··: .. ;·-.. · .· ~-~ . ·, •.'' '' ' .' .. _:·.-:_.: . .. , .. : '•/ .. ··· . ··:· '•,• .. . . ,· .' .,· ·. .. '· .. .. ·. .·,: .. ·., . ... • .... .-. • j • ,,-•• . , . .' .. , •,. · . "' ;: . ... ,•,·· .•.-.·. I••· · .. · .. . .:, ' •• .,,. • • J ~ ... • .· i' . .... :'., • Geotechnical • Coastal • Geologic • Environmental 5741 Palmer Way • Carlsbad, California 92010 • {760) 438-3155 • FAX (760) 931-0915 Mr. Wllllam Lynn 6575 Black Rail Road Carlsbad, California 92008 August 23, 2004 W.O. 3460-A2-SC Subject: Geotechnical Review of -Structural Plans\ Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California References: 1. "Structural Plans for: Lynn Residence, 4 sheets, Project No. 043272," dated March 1 and 11, and April 14 and 22, 2004, by Engineering Design Group, Inc. 2. "Preliminary Geotechnical Evaluation, 6575 Black Rail Road, Proposed Subdivision, Carlsbad, San Diego County, California," W.O. 3460-A-SC, dated November 27, 2002, by GeoSoils, Inc. 3. "Uniform Building Code," dated 1997, by International Conference of Building Officials. Dear Mr. Lynn: In accordance with a your request, GeoSoils, Inc. (GSI) has performed a geotechnical review of the structural plans, Sheets S-1, S-1 A, S-2, and D-3 for the Lynn Residence, (Parcel 4), prepared by Engineering Design Group, Inc. (see Reference No. 1). Unless specifically superceded herein, the conclusions and recommendations contained in Reference No. 2 remain pertinent and applicable, and should be appropriately implemented during planning, design, and construction. The plans, notes, and details reviewed appear to be in general conformance with the recommendations provided by this office and presented in the referenced report by GSI, from a geotechnical viewpoint. The following supplemental comments and recommendations are provided herein, and should be incorporated into the project design and construction. STRUCTURAL PLAN REVIEW 1. Foundation Note No. 1 on Sheet S-1 should include the complete title of GSI (2002) for easier referencing. 2. On a preliminary basis, all continuous footings to support raised wood floors should be embedded into properly compacted fill a minimum of 12 inches deep for one-story floor loads, and 18 inches deep for two-story floor loads below the lowest adjacent grade for very low to low expansive soils {Expansion Index [E.I.] = 0 to 20}. All isolated pad footings should be embedded into properly compacted fill a minimum of 24 inches deep below the lowest adjacent grade and be connected to the perimeter foundation via grade beam in at least one direction. All footings should be minimally reinforced with two No. 4 reinforcing bars placed near the top and bottom of the footing (total • of four bars). Final foundation design and construction recommendations will be provided atthe conclusion of grading, based upon the E.I. of soils exposed at finish grade. 3. All below grade (basement) walls should be provided with an adequate backdrain system consisting of 4-inch diameter perforated PVC or ABS pipe (schedule· 40 or equivalent) encased in either Class 2 permeable filter material or ½ inch to ¾ inch gravel and wrapped In approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 h~:>rizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential; continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, {panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain), with increased hydrostatic pressure. Materials with an E.I. potential of greater than 65 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Backdrains should be designed to flow at a minimum of 1 percent to an approved outlet or sump. The sump should be designed by the civil engineer to not allow water to saturate soils beneath the slab or near the foundation. Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than ± 100 feet apart, with a minimum of two outlets, one on· each end. The use of weep holes only in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.I. <90). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining· structures. The use of a waterstop should be considered for all concrete and masonry joints. 4. In order to provide uniform bearing conditions due to the presence of non-uniform paleoliquefaction features, mat slab foundations are recommended as an alternative to post-tension slabs, to support all slab-on-grade floors. Preliminary mat slab foundation recommendations are provided herein. Final mat slab design and construction recommendations will be provided at the conclusion of grading based upon the E.I. of soils exposed at finish grade. Mr. William Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro C•nSnil.c. lne. W.O. 3460-A2-SC August 23, 2004 Page2 Provide Surface Drainage ©waterproofing Membrane (optional) ® Weep Hole Finished Surface .±12" DETAILS N .· T . S . 12" 2 Native Backfill Slope or Level Native Backfill @ Rock @ Filter Fabric Native Backfill @ Pipe (!) WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. @ ROCK: 3/4 to 1-1/2" (inches) rock. @ FILTER FABRIC: Miraft ;t.40N or approved equivalent; place fabric flap behind core. @ PIPE: 4" ·cinches) diameter perforated PVC. schedule 40 or approved alternative with minimum ot' 1 % gradient to proper outlet point. @ WEEP HOLE: . Minimum 2" (Inches) diameter placed at 20' (feet) on centers along the wall, and 3" (Inches) above finished surface. (No weep holes for basement walls.) • TYPICAL RETAINING WALL BACKFILL AND DRAINAGE DETAIL DETAIL 1 Geotechnical • Geologic • Environmental DETAILS N . T . S . 2 Native Backfill Slope or Level Native Backfill ©waterproofing Membrane (optional) 1 @ Weep Hole @ Filter Fabric Finished Surface ·@ Pipe @ WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. (a> DRAIN: Mlradraln 6000 or J-draln 200 or equivalent for non-waterproofed walls. Mlradraln 6200 or J-draln 200 or equivalent for waterproofed walls. @ FILTER FABRIC: @ PIPE: Mlrafl 140N or approved equivalent; place fabric flap behind care. 4" (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1 % gradient to proper outlet point. @ WEEP HOLE: Minimum 2" (Inches) diameter placed at 20' (feet) on centers along the wall·, and 3" (Inches) above finished surface. (No weep holes for basement walls.) RETAINING WALL BACKFILL AND SUBDRAIN DETAIL GEOTEXTILE DRAIN DETAIL 2 Geotechnical • Geologic • Environmental H DETAILS N . T . S . 2 Native Backfill Provide Surface Drainage ±12" ® Weep Hole Finished Surface H/2 min. @ Waterproofing Membrane (optional) ·@ Filter Fabric : @ Roe Heel Width @ WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. @ CLEAN SAND BACKFILL: Slope or Level Must have sand equivalent value of 30 or greater; can be denslfled by water jetting. @ FILTER FABRIC: Mlrafl 140N or approved equivalent. @ ROCK: 1 cubic foot per linear feet of pipe or 3/4 to 1-1/2" (Inches) rock. @ PIPE: 4" (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1 % gradient to proper outlet point. @WEEP HOLE: Minimum 2" (Inches) diameter placed at 20' (feet) on centers along the wall, and 3" (Inches) above finished J>Urface. (No weep holes for basement walls.) • RETAINING WALL AND SUBDRAIN DETAIL CLEAN SAND BACKFILL DETAIL 3 Geotechnical • Geologic • Environmental PRELIMINARY RECOMMENDATIONS-MAT SLAB FOUNDATIONS {ALTERNATIVE) The structural mat should have a double mat of steel (minimum No. 4 reinforcing bars located at 12 inches on center each way-top and bottom), and a minimum thickness of 1 O inches. A thickened edge (12 inches below the lowest adjacent grade) should be provided across the entrance to the garage. Mats may be designed by UBC Section 1815 (Div. Ill) methods using an Effective Plasticity Index of 15. Mat slabs may be designed for a modulus of subgrade reaction (Ks) of 80 pci when placed on compacted very low expansive silty sand (E.I. Oto 20). In moisture sensitive slab areas, a continuous visqueen vapor barrier (properly sealed per the UBC) should be utilized and be of sufficient thickness to provide a durable separation of foundation from soils (10-mils thick). The vapor barrier should be sealed to provide a continuous water-proof barrier under the entire s.lab. The vapor barrier should be sandwiched between two 2-inch thick layers of sand (SE>30}. Specific soil presaturation is not required for very low expansive soils. However, the slab subgrade moisture content should be at or slightly above the soil's optimum moisture content to a depth of 12 inches below grade. The above recommendations are based upon the expansion index testing performed in preparation of the preliminary geotechnical evaluation (see Reference No. 2). Final foundation recommendations will be provided based upon expansion index testing of soils exposed at finish grade. UPDATE WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (Class 2 permeable filter material or Class 3 aggregate base) or native materials (up to and including an E.I. of 65) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls, below grade, should be water-proofed or damp-proofed, depending on the degree of moisture protection desired. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Mr. WIiiiam Lynn 6575 Black Rall Road, Carlsbad File:e:\wp9\3400\3460a2.gro W.O. 3460-A2-SC August 23, 2004 Page6 Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should ·be designed for an at-rest equivalent fluid pressure (EFP) of 65 pounds per cubic foot (pcf), plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 1 o feet high. Design parameters for walls less than 3 feet in height may be superceded by City and/or County standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure ag~inst the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. Level* 2 to 1 35 50 45 60 * Level backfill behind a retaining wall is defined as compacted earth materials, ro erl drained, without a slo e for a distance of 2H behind the wall.- Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options discussed below. Bijckdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or %-inch to ¾-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall Mr. William Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro W.O. 3460-A2-SC August 23, 2004 Page? may be constructed in accor~ance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an E.I. potential of greater than 65 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than ± 100 feet apart, with a minimum of two outlets, one on each end. The use of only weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.I. <90). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1/360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be placed no greater than 20 feet on-center, •in accordance with the structural engineer's/wall designer's recommendations, regardless of whether or nottransition conditions exist. Expansion joints should be sealed with a flexible, non-shrink grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a11 (above) and until such transition is between 45 and 90 degrees to the wall alignment. Mr. WIiiiam Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro W.O. 3460-A2-SC August 23, 2004 Pages TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS Slope Creep Soils at the site may be expansive and therefore, may become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth of these shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 1 o feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top ot slope fences/walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication/swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to any homeowners and homeowners association. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 1 0 feet, some settlement and tilting of the walls/fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be constructed on deepened foundations without any consideration for creep forces, where the expansion index of the materials comprising the outer 15 feet of the slope is less than 50, or a combination of grade beam and caisson foundations, for expansion indices greater than 50 comprising the slope, with creep forces taken into account. The grade beam should be at a minimum of 12 inches by 12 inches in cross section, supported by drilled caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet on center, and with a minimum embedment length of 7 feet below the bottom of the grade beam. The strength of the concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons should be in accordance with the recommendations of the project structural engineer, and include the utilization of the following geotechnical parameters: Mr. William Lynn 6575. Black Rall Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro W.O. 3460-A2-SC August23,2004 Page9 Creep Zone: Creep Load: Point of Fixity: Passive Resistance: Allowable Axial Capacity: Shaft capacity : Tip capacity: 5-foot vertical zone below the slope face and projected upward parallel to the slope face. The creep load projected on the area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, to a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. 350 psf applied below the point of fixity over the surface area of the shaft. 4,500 psf. DRIVEWAY. FLATWORK. f\ND OTHER IMPROVEMENTS The soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify any homeowners or homeowners association of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1 . The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the· soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. If very ldw expansive soils are present, only optimum moisture content, or greater, is required and specific presoaking is not Mr. WIiiiam Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro W.O. 3460-A2-SC August23,2004 Page 10 warranted. The moisture content of the subgrade should be verified within 72 hours prior to pouring concrete. 2. Concrete slabs should be cast over a non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are present, the rock or gravel or sand may be deleted. The layer or subgrade should be wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. If subgrade soils· within the top 7 feet from finish grade are very low expansive soils (i.e., E.I. ~20), then 6x6-W1 .4xW1 .4 welded-wire mesh may be substituted for the rebar, provided the reinforcement is placed on chairs, at slab mid-height. The exterior slabs should be scored or saw cut, ½ to 3/a inches deep, often enough so that no section is greater than 1 0 feet by 10 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. 6. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. Mr. WIiiiam Lynn · 6575 Black Rail Road, Carlsbad File:e:\wp9\3400\3460a2.gro r ..... n.Cnllc. lnlP.. W.O. 3460-A2-SC August 23, 2004 Page 11 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. If very low expansion soils are present, footings need only be tied in one direction. 9. Any masonry landscape walls that are to be constructed throughout the· property should be grouted and articulated In segments no more than 20 feet long. these segments should be keyed or doweled together. 10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should p·rovide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including post-construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner or homeowners association. 12. Air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. A/C waste water lines should be drained to a suitable non-erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. UPDATE DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post-construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occurthroughoutthe life of the slope, and is anticipated to potentially affect improvements or structures (i.e., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of . approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located Mr. William Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro W.O. 3460-A2-SC August 23, 2004 Page 12 within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the 1997 UBC and/or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. Expansion joints in walls should be placed no greater than 20 feet on-center, in accordance with the structural engineer's recommendations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and/or any homeowners association. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustair:i plant life should be provided for planted slopes. Over-watering should be avoided as it can adversely affect site improvements, and cause perched groundwater conditions. Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be . minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent bur.rowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. · Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that future landscaping or construction activities do not create adverse drainage conditions. · Mr. WIiiiam Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro W.O. 3460-A2-SC August 23, 2004 Page 13 Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground~ In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of 1 percent sloping away from structures, and whenever possible, should be above.adjacent paved areas. Consideration should be given to avoiding construction of planters .adjacent to structures {buildings, pools, spas, etc.}. Pad drainage should be directed toward the street or other approved area(s}. Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. · Toe of Slope ·Drains/Toe Drains Where significant slopes intersect pad areas, surface drainage down the slope allows for some seepage into the subsurface materials, sometimes creating conditions causing or contributing to perched and/or ponded water. Toe of slope/toe drains may be beneficial in the mitigation of this condition due to surface drainage. The general criteria to be utilized by the design engineer for evaluating the need for this type of drain is as follows: • Is there a source of irrigation above or on the slope that could contribute to saturation of soil at the base of the slope? • Are the slopes hard rock and/or impermeable, or relatively permeable, or; do the slopes already have or are they proposed to have subdrains (i.e., stabilization fills, etc.}? • Was the lot at the base of the slope overexcavated or is it proposed to be overexcavated? Overexcavated lots located at the base of a slope could accumulate subsurface water along the base of the fill cap. · • Are the slopes north facing? North facing slopes tend to receive less sunlight (less evaporation} relative to south facing slopes and are more exposed to the currently prevailing seasonal storm tracks. · • What is the slope height? It has been our experience that slopes with heights in excess of approximately 1 o feet tend to have more problems due to storm runoff and irrigation than slopes of a lesser height. Mr. William Lynn 6575 Black Rail Road, Carlsbad . Flle:e:\wp9\34!)0\3460a2.gro W.O. 3460-A2-SC August23,2004 Page 14 • Do the slopes "toe out" into a residential lot or a lot where perched or ponded water may adversely impact its proposed use? Based on these general criteria, the construction of toe drains may be considered by the design engineer along the toe of slopes, or at retaining walls in slopes, descending to the rear of such lots. Following are Detail 4 (Schematic Toe Drain Detail) and Detail 5 (Subdrain Along Retaining Wall Detail). Other drains may be warranted due to unforeseen conditions, homeowner Irrigation, or other circumstances. Where drains are constructed during grading, including subdrains, the locations/elevations of such drains should be surveyed, and recorded on the final as-built grading plans by the design engineer. It is recommended that the above be disclosed to all interested parties, including homeowners and any homeowners association. Erosion Control Cut and fill slopes will be subject to surficial erosion during and after grading.· Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. · · Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum distance of 1 O feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. -Graded slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems}. From a · geotechnicaf standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate _the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes Mr. Willlam Lynn 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro CaoSoils. lne. W.O. 3460-A2-SC August 23, 2004 Page 15 DETAILS N . T . S . SCHEMATIC TOE DRAIN DETAIL Drain Pipe Drain May Be Constructed into, or at, the Toe of Slope Permeable Mater! • 12" Minimum 24" Minimum NOTES: 1.) Soll Cap Compacted to 90 Percent Relative Compaction. 2.) Permeable Material May Be Gravel Wrapped in Filter Fabric (Mlrafl 140N or Equivalent). 3.) 4-lnch Diameter Perforated Pipe (SDR 35 or Equivalent) with Perforations Down. 4.) Pipe to Maintain a Minimum 1 Percent Fall. 5.) Concrete Cutoff Wall to be Provided at Transition to Solid Outlet Pipe. 6.) Solid Outlet Pipe to Drain to Approved Area. 7.) Cleanouts are Recommended at Each Property Line. SCHEMATIC TOE DRAIN DETAIL DETAIL 4 Geotechnical • Coastal • Geologic • Environmental DETAILS N .T.S. 2:1 SLOPE (TYPICAL)~ TOPOFWALL . NOTES: 1.) Soll Cap Compacted to 90 Percent Relative Compaction. RETAINING WALL ~ 12" MIN 2.) Permeable Material May Be Gravel Wrapped In Filter Fabric (Mlrafl 140N or Equivalent). FINISHED ,GRADE \ 12 3.) 4-lnch Diameter Perforated Pipe (SDR-35 of Equivalent). wl'th MIRAFI 140 FILTER FABRIC Perforations Down. OR EQUAL 3/4' CRUSHED GRAVEL 4"DRAIN 4.) Pipe to Maintain a Minimum 1 Percent Fall. 5.) Concrete Cutoff Wall to be Provided at Transition to Solid Outlet Pipe. 6.) Solid Outlet Pipe to Drain to Approved Area. 7.) Cleanouts are Recommended at Each Property Line. 8.) Compacted Effort Should Be Applied to Drain Rock. SUBDRAIN ALONG RETAINING WALL DETAIL NOTTO SCALE SUBDRAIN ALONG RETAINING WALL DETAIL DETAIL 5 Geotechnical • Coastal • Geologic • Environmental or non-erosive devices that will carry the water away from the house. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. · Site Improvements Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological cir geotechnical aspects of. design and construction of said improvements could be provided upon request. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench, and retaining wall backfills. TIie Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading ·of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street and parking areas and utility trench and retaining wall backfills. Mr. WIiiiam Lynn 6575 Black Rall Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro GeoSoils. lne. W.O. 3460-A2-SC August 23, 2004 Page 18 Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concret~ form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompactiori of the subgrade materials would be recommended atthattime. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching Considering the nature of the onsite soils, it should be anticipated that caving _or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be observed by one of our representatives and minimally conform to CAL-OSHA and local safety codes.· Utility Trench Backfill 1 . All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to verify the desired results. 2. Exterior trenches adjacent to, and within areas extending below a 1 :1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along · with probing, should be accomplished to verify the desired results. 3. All trench excavations should conform to CAL-OSHA and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. Mr. WIiiiam Lynn 6575 Black Rall Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro W.O. 3460-A2-SC August23,2004 Page 19 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that obseryation and/or testing be performed by GSI at each of the following construction stages: • • • • • • • •. • • • • During grading/recertification . During significant excavation (i.e., higher than 4 feet) . During placement of subdrains, toe drains, or other subdrainage devices, prior to placing fill and/or backfill. After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Prior to pouririg any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before t~e placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e., visqueen, etc.). During retaining wall subdrain installation, prior to backfill placement. During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. I During slope construction/repair . When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. A report of geotechnical observation and· testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. GSI should review project sales documents to homeowners/homeowners associations for geotechnical aspects, including irrigation practices, the conditions outlined above, etc., prior to any sales. At that stage, GSI will provide homeowners maintenance guidelines which should be incorporated into such documents. · Mr. William Lynn W.O. 3460-A2-SC August 23, 2004 Page 20 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro G4!oSoil~. lne. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations and o~her elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer/designer. The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and deflections in the various slab, foundation, and other elements in order to develop appropriate, design-specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer/designer should consider all applicable codes and authoritative sources where needed. If analyses • by the structural engineer/designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely that some, more restrictive details will be required. If the structural engineer/de~igner has any questions or requires further assistance, they should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate potential distress, the foundation and/or improvement's designer should confirm to GSI and the governing agency, in writing, that the proposed foundations and/or improvements can tolerate the amount of differential settlement a.nd/or expansion characteristics and design criteria specified herein. PLAN REVIEW Final project plans should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Mr. William Lynn 6575 Black Rall Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro CaoSoil.c. lne. W.O. 3460-A2-SC August 23, 2004 Page 21 Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subject to change with time. GSI assumes no responsibility or -liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. The opportunity to be of service is greatly appreciated. If you have any questions, please do not hesitate to call our office. Respectfully submitted, ~-~O ~;?Boehmer Staff Geologist RB/ JPF/DWS/jk Distribution: (4) Addressee Mr. WIiiiam Lynn · 6575 Black Rail Road, Carlsbad Flle:e:\wp9\3400\3460a2.gro CaoSoih. ltte. W.O. 3460-A2-SC August 23, 2004 Page 22 ·:··.·, ,·, '• . •.1·: ' -~ .: .. ·· ., :-: .:, '•' ' -·,• . ... , .. ·, \ . ... : ~··:· ; • . ' • ·::' • ."t· ... ~~ : , ~-.. ',,_,.:,· \ '•. ': :··. ,•,: ,·1 .. : . • .... : ..... : "., .. :• .. · '. ,· .,•.·,·.' ' . ·: -•: . ::·. ,, ' ..... ,: ·••.: ' ... ' .' ,, . ·,•,,• ',. .· ... , ,;·,· .. ::. ' .~ . '. ~ :· . ..... ,~ . ··, .· .. '• . _., ' : ·:. ~ . ~. ' : .·. ,_ . . :· .... :• ... :· .. ·:· ':,, ' '•. . . .,. ,··~. .. ... :, ' , ••I: • ..: ;• ...... .., •· :-.·.• .•.. '·._: .·- ·.!,':·: , .. \. ·,· '. :• .' .: . '. ,·. · . .' ..., · .... ,· .. I ••1, • ~ .. :. · .. : ·>· •. , ... '. .. . .· .. ·,·,,·, • ,: ~•I \ ·. <:: .:··•,'.• . . .. ··~· ·' ·: · ... :·. .. -: : . : ··: ·,_• ,·: ' -~ . ' ;, . . ' . ... · ·. . .:.~,-NicdoMPAtf;oN··~e~·o~i~riF:,<l~·~-~1:N·~: .... .-:-: · . :-. su1LoJ~~ 'i~Ao )(R:EA,;PARC..EL.-4; )~s1s··~iAc.K RAiL• RoAo.-: ' bARL$B,AP/SAN:_olEGQ;t ·ou~tv·,': CAl;JFORNIA · ... · · .. ... :· .. •· . ",• . ,· .. ·.·," ·. " ' '·.i->_:\',··:::.:'./ ,.:.,:: .. ,· ... '. :,·.: ... , :,: · .FOR :,-··.:. ··. .. •,·.· .-.. . .. :·.:.. ,··•;t ' .. ~ .. :·:~ .•. ~: .·~·.\:· \:.j: ·· . .-,:·: ~.-.... ~•: .. ' ··.,. .. ·: · ,,. . ··. · MR •. ANO .. MRS~-WILLIAIVl.~YNN ,• .· ,• ··.:• . "',, .,.. , . ;•,: . .· ' .. ., .:•.,.·.· .. ... •. . .. •·6S7!f·eLAcK'RAIL.RoAo .·.·. • •. • : ' '; • , 4 , ~. ,-I • ,• , , , ••. • ( r , •, , • 'J, .'• .. . . ' . : ~ :. ·:. . ·. ,; ·•: ,., : . •,·' ' ··. · · .. :cARLS.BAD, .CALIFORNIA :92009 ... . . i . . .. . :\. ·: •._: :' .... :·· .. ;-~ .. . ,. . . '.' ,• ', .•·, · ,w.o·. 34601:.,;e .. sc·o . ' '· ': . . :.~ .. '··.·. ,i •,• --' '· .. ,• ' . I ••• · .. ~. -· ·,•, .. ;· .. : · .. .. ;··. -.· SEPTEMBER .i4 2004 ·=.,:: ..... · .. _·:::•.: ::: .'-.~·,:-.::·,, . ···,. · .. ·.,, ·'·:-:' • I •• ,• . :,•' .. ,, ... ..... :.·. • .. ··. .,-: ...... •, :· ,: ·,• ,,,. .· •.· '• ; : . .-·. . . . ' ~ , .... -~· .·' .· . , ... :· .... • I,'.'•:,,:,, ·,.·· . ··! .. · ... ' '• ·· .. · .... ' '•, ·'· :'. , . ;: . 4/•, ,··.· '·:: 5741 Palmer Way Geotechnical • Coastal • Geologic • Environmental Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 September 14, 2004 W.O. 3460-B1-SC Mr. and Mrs. WIiiiam Lynn 6575 Black Rail Road Carlsbad, California 92009 Subject: References: Final Compaction Report of Grading, Building Pad Area, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County: California 1. "Grading Plan for: Lynn Minor Subdivision, City of Carlsbad, California," Project No. MS 01 -04, dated May 4, 2000, by MLB Engineering. 2. "Preliminary Geotechnlcal Evaluation, 6575 Black Rail Road, Carlsbad, San Diego County, California," W.O. 3460-A-SC, November 27, 2002, by GeoSolls, Inc. 3. "Uniform Building Code, International Conference of Building Officials, Vol. 1, 2, and 3, Whittier, Californla, 1997. Dear Mr. and Mrs. Lynn: This report presents a summary of the geotechnical testing and observation services provided by GeoSoils, Inc. (GSI) during the rough earthwork phase of development for the new construction at the subject site. Earthwork commenced August 4, 2004, and was generally completed on August 13, 2004. Survey of line and grade and locating of the building footprint was performed by others, and not performed by GSI. The purpose of grading was to prepare one relatively ·Ievel building pad for the construction of one single-family residence and driveway improvements. Based on the observations and testing services provided by GSI, it is our opinion that the building pad area appears suitable for its intended use. ENGINEERING GEOLOGY The geologic conditions exposed during grading were regularly observed by a representative from our firm. The geologic conditions encountered generally were as anticipated and presented in the referenced report (GSI, 2002). GEOTECHNICAL ENGINEERING Preparation of Existing Ground 1. Prior to grading, the major surflcial vegetation was stripped and hauled offsite. 2. Removals consisted of undocumented artificial fill, topsoil/colluvium and near-surface weathered terrace deposits within areas of proposed improvements. Overexcavatlon l The building pad area was overexcavated to at least 3 feet below pad grade, in accordance with Reference No. 2. Overexcavation was completed to at least 5 feet outside for the building footprint. The exposed bottom was reprocessed, moisture conditioned, and recompacted prior to fill placement. The actual location of the proposed footprint of the building was provided by others. FIii Placement Fill, consisting of native and import soils, was placed in 6-to 8-inch lifts, watered, and mixed to achieve at least optimum moisture <;:ontent. The fill was then compacted to 90 percent of the laboratory standard via mechanical means. The approximate limits of fill, placed under the purview of this report, are indicated on Plates 1 and 2. FIELD TESTING 1. Field density tests were performed using nuclear densometer (ASTM Test Methods D-2922 and D-3017), and sand cone (ASTM Test Method ASTM D-1556). The test results taken during grading are presented in the attached Table 1, and the locations of the tests taken during grading are presented on Plates 1 and 2. 2. Field density tests were taken at periodic intervals and random locations to check the compactive effort provided by the contractor. Based upon the grading operations observed, the test results presented herein are considered representative of the compacted fill. 3. Visual classification of the soils in the field was the basis for determining which maximum density value to use for a given density test. Mr. and Mrs. WIiiiam Lynn 6575 Blackrall Road, Carlsbad Flle:e:\wp9\3400\3460b. fcr2 W.O. 3460-81-SC September 14, 2004 Page2 LABORATORY TESTING Maximum Density Testing The laboratory maximum dry density and optimum moisture cont~nt for the major soil type within this construction phase were determined according to test method ASTM D-1557. The following table presents the results: Expansion Index Expansive soil conditions have been evaluated for the site. A representative sample of the soils near pad grade was recovered for expansion index testing. Expansion Index (E.I.) testing was performed in general accordance with Standard 18-2 of the Uniform Building Code ([UBC], International Conference of Building Officials [ICBO], 1997). The test results indicate an E.I. of 13, and the corresponding expansion classification of very low. Corrosion/Sulfate Typical samples of the site materials were analyzed for corrosion/soluble sulfate potential. The testing included determination of pH, soluble sulfates, and saturated resistivity. At the time of this report the results were not available. An addendum to this report will be issued when the testing is complete. CONCLUSIONS AND RECOMMENDATIONS Unless superseded by recommendations presented herein, the conclusions and recommendations contained in (see Reference No. 2) remain valid and applicable, and should be properly implemented. MAT SLAB FOUNDATION In order to mitigate non-uniform bearing conditions, due to the presence of paleoliquefaction features, all slab-on-grade floors, for the proposed residence, should be supported by a mat slab foundation, as an alternative to a post-tension slab. The structural mat should have a double mat of steel (minimum No. 4 reinforcing bars located at Mr. and Mrs. WIiiiam Lynn 6575 Blackrail Road, Carlsbad Flle:e:\wp9\3400\3460b.fcr2 GaoSoil.c. Inc. W.O. 3460-81-SC September 14, 2004 Page3 12 inches on center each way -top and bottom) and a minimum thickness of 1 O inches. A thickened edge (12 inches below the lowest adjacent grade) should be provided across the entrance to the garage. Mats may be designed by UBC Section 1815 (Div. Ill) methods using an Effective Plasticity Index of 15. Mat slabs may be designed for a modulus of subgrade reaction (Ks) of 80 pci when placed on compacted very low expansive soils (E.I. =Oto 20). In moisture sensltivu slab areas, a visqueen vapor barrier should be utilized and be of sufficient thickness to provide a durable separation of foundation from soils (10-mlls thick). The vapor barrier should be sealed to provide a continuous water-proof barrier under the entire slab, per the UBC. The vapor barrier should be sandwiched by two 2-inch thick layers of sand (SE>30). Specific soil presaturation is not required for.very low expansive soils. However, the slab subgrade moisture content should be at or slightly above the soil's optimum moisture content to a depth of 12 Inches below grade. ' WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (Class 2 permeable filter material or Class 3 aggregate base) or native materials (up to and including an E.I. of 65) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls, below grade, should be water-proofed or damp-proofed, depending on the degree of moisture protection desired. The foundation system for the proposod retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches), into properly compacted fill or dense terrace deposits, and should be 24 inches in width. There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pounds per cubic foot (pcf), plus any applicable surcharne loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Mr. and Mrs. WIiiiam Lynn 6575 Blackrail Road, Carlsbad Flle:e:\wp9\3400\3460b.fcr2 W.O. 3460-81-SC September 14, 2004 Page4 Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 1 o feet high. Design parameters for walls less than 3 feet in height may be superceded by City - and/or County standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. Level* 2 to 1 35 50 45 60 * Level backfill behind a retaining wall is defined as compacted earth materials, ro erl drained, without a slo e for a distance of 2H behind the wall. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or ½-inch to ¾-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. . For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an E.I. potential of greater than 65 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Mr. and Mrs. WIiiiam Lynn 6575 Blackrail Road, Carlsbad Flle:e:\wp9\3400\3460b.fcr2 W.O. 3460-81-SC September 14, 2004 Page5 Provide Surface Drainage ©waterproofing Membrane (optional) @ Weep Hole Finished Surface ,:!:12" DETAILS N . T . S . 2 Natlvo Backfill Slope or Level Native Backfill @ Filter Fabric Native Backfill @ Pipe (!) WATERPROOFING MEMBRANE (optional): Liquid boot or approved equlvalent. (I) ROCK: 3/4 to 1-1/2" (Inches) rock. @ FILTER FABRIC: Mlrafi 140N or approved equlvalent; place fabric flap behind core. @ PIPE: 4" (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1 % gradient to proper outlet point. @WEEP HOLE: Minimum 2" (Inches) diameter placed at 20' (feet) on centers along the wall, and 3" (Inches) above finished surface. (No weep holes for basement walls.) • TYPICAL RETAINING WALL BACKFILL AND DRAINAGE DETAIL DETAIL 1 Geotechnical • Geologic • Environmental DETAILS N . T . S . 2 Native Backfill Provide Surface Drainage Slope or Level Native Backfill <Dwaterproofing Membrane (optional) @weep Hole @ Filter Fabric Finished Surface @ Pipe @ WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. @ DRAIN: Miradraln 6000 or J-draln 200 or equivalent for non-waterproofed walls. Mlradrain 6200 or J-draln 200 or equlvaient for waterproofed walls. @ FILTER FABRIC: Mirafl 140N or approved equivalent; place fabric flap behind care. @ PIPE: 4" (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1 % gradient to· proper outlet point. @WEEP HOLE: Minimum 2" (Inches) diameter placed at 20' (feet) on centers along the wall, and 3" (Inches) above finished surface. (No weep holes for basement walls.) • RETAINING WALL BACKFILL AND SUBDRAIN DETAIL GEOTEXTILE DRAIN DETAIL 2 . Geotechnical • Geologic • Environmental H DETAILS N . T . S . Native Backfill Provide Surface Drainage ±12" H/2 min. © Waterproofing : Membrane (optional) Slope or Level ® Weep Hole · 3___.··..._~~-+--------@ Clean @ Filter Fabric : Finished Surface · © Roe Heel Width (i) WATERPROOFING MEMBRANE (optionai): · Liquid boot or approved equivalent. @ CLEAN SAND BACKFILL: Must have sand equivalent value of 30 or greater; can be denslfled by water jetting. @ FILTER FABRIC: Mlrafi 140N or approved.equivalent. @ ROCK: . 1 cubic foot per linear feet of pipe or 3/4 to 1-1/2" (inches) rock. @ PIPE: Sand Backfill 4" (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1 % gradient to proper outlet point. @WEEP HOLE: Minimum 2" {Inches) diameter placed at 20' (feet) on centers along the wall, and 3" (Inches) above finished surface. (No weep holes for basement walls.) • RETAINING WALL AND SUBDRAIN DETAIL CLEAN SAND BACKFILL DETAIL 3 Geotechnical • Geologic • Environmental Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than ± 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement o~ the top 18 inches compacted with native soil (E.I. .::5.90). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1 /360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be placed no greater than 20 feet on-center, in accordance with the structural engineer's/wall designer's recommendations, regardless of whether or not transition conditions exist. Expansion joints should be sealed with a flexible, non-shrink grout. Some cracking at the transition should be anticipated and disclosed to interested parties. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS Slope Creep Soils at the site may be expansive and therefore, may become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth of these shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water Mr. and Mrs. William Lynn 6575 Blackrail Road, Carlsbad Flle:e:\wp9\3400\3460b.fcr2 W.O. 3460-81-SC September 14, 2004 Page9 percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of. slope materials experience a very .slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 1 o feet, this creep related soil movement will typically Impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences/walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication/swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to any homeowners and homeowners association. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 1 0 feet, some settlement and tilting of the walls/fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be constructed on deepened foundations without any consideration for creep forces, where the expansion index of the materials comprising the outer 15 feet of the slope is less than 50, or a combination of grade beam and caisson foundations, for expansion indices greater than 50 comprising the slope, with creep forces taken into account. The grade .• beam should be at a minimum of 12 inches by 12 inches in cross section, supported by drilled caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet on center, and with a minimum embedment length of 7 feet below the bottom of the grade beam. The strength of the· concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons should be in accordance with the recommendations of the project structural engineer, and include the utilization of the following geotechnical parameters: Creep Zone: Creep Load: Point of Fixity: Mr. and Mrs. WIiiiam Lynn 6575 Blackrail Road, Carlsbad File:e:\wp9\3400\3460b. fcr2 5-foot vertical zone below the slope face and projected upward parallel to the slope face. The creep load projected on the .area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Located a distance of 1.5 times the caisson's diameter, below the creep zone. ~oSoil.c. lne. W.O. 3460-81-SC September 14, 2004 Page 10 Passive Resistance: Allowable Axlal Capacity: Shaft capacity : n p capacity: Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, t<;> a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. 350 psf applied below the point of fixity over the surface area of the shaft. 4,500 psf. DRIVEWAY, FLATWORK. AND OTHER IMPROVEMENTS The soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify any homeowners or homeowners association of this long- term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content,· to a depth of 18 inches below subgrade elevation. If very low expansive soils are present, only optimum moisture content, or greater, is required and specific presoaking is not warranted. The moisture content of the subgrade should be verified within 72 hours prior to pourinQ concrete. 2. Concrete slabs should be cast over a non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are present, the.rock or gravel or sand may be deleted. The layer or subgrade should be wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. Mr. and Mrs. Wllllam Lynn 6575 Blackrall Road, Carlsbad File:e:\wp9\3400\3460b. fcr2 W.O. 3460-81-SC September 14, 2004 Page 11 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. · In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minim_um of No. 3 bars placed at 18 inches on center, in each direction. If subgrade soils within the top 7 feet from finish grade are very low expansive soils (i.e., El ~20), then 6x6-W1 .4xW1 .4 welded-wire mesh may be substituted for the rebar, provided the reinforcement is placed on chairs, at slab mid-height. The exterior slabs should be scored or saw cut,-½ to 3/e inches deep,. often enough so that no section is greater than 1 o feet by 1 O feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. · 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a mini,:num of 2,500 psi. 6. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. If very low expansion soils are p~esent, footings need only be tied in one direction. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 1 O. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11 . Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including post-construction settlement, if relatively flat yard drainage gradi~:mts are not periodically maintained by the homeowner or homeowners association. Mr. and Mrs. WIiiiam Lynn 6575 Blackrall Road, Carlsbad Flle:e:\wp9\3400\3460b. fcr2 c-. .. ~nil.c. fnif!. W.O. 3460-81-SC September 14, 2004 Page 12 12. Air conditioning (NC) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. NC waste water lines should be drained to a suitable non-erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices . should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post-construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and Is anticipated to potentially affect improvements or structures (i.e., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally n.ot practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the 1997 UBC ~nd/or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. Expansion joints in walls should be placed no greater than 20 feet on-center, in· accordance with the structural engineer's recommendations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and/or any homeowners association. Mr. and Mrs. Wllllam Lynn 6575 Blackrail Road, Carlsbad Flle:e:\wp9\3400\3460b.fcr2 CeoSoil.s. lne. W.O. 3460-B1-SC September 14, 2004 Page 13 Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability Is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-watering should be avoided as it can adversely affect site improvements, and cause perched groundwater conditions. Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation Is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, ·mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance offoundations, hardscape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground. In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of 1 percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Mr. and Mrs. WIiiiam Lynn 6575 Blackrail Road, Carlsbad Ale:e:\wp9\3400\3460b.fcr2 W.O. 3460-81-SC September 14, 2004 Page 14 Toe of Slope Drains/Toe Drains Where significant slopes intersect pad areas, surface drainage down the slope allows for some seepage into the subsurface materials, sometimes creating conditions causing or contributing to perched and/or ponded water. Toe of slope/toe drains may be beneficial in the mitigation of this condition due to surface drainage. The general criteria to be utilized by the design engineer for evaluating the need for this type of drain is as follows: • Is there a source of irrigation above or on the slope that could contribute to saturation of soil at the base of the slope? • Are the slopes hard rock and/or impermeable, or relatively permeable, or; do the slopes already have or are they proposed to have subdrains (i.e., stabilization fills, etc.)? • Was the lot at the base of the slope overexcavated or is it proposed to be overexcavated? Overexcavated lots located at the base of a slope could accumulate subsurface water along the base of the fill cap. • Are the slopes north facing? North facing slopes tend to receive less sunlight (less evaporation) relative to south facing slopes and are more exposed to the currently prevailing seasonal storm tracks. • What is the slope height? It has been our experience that slopes with heights in excess of approximately 1 o feet tend to have more problems due to storm runoff and irrigation than slopes of a lesser height. • Do the slopes "toe out" into a residential lot or a lot where perched or ponded water may adversely impact its proposed use? Based on these general criteria, the construction of toe drains may be considered by the design engineer along the toe of slopes, or at retaining walls in slopes, descending to the rear of such lots. Following are Detail 4 (Schematic Toe Drain Detail) and Detail 5 (Subdrain Along Retaining Wall Detail). Other drains may be warranted due to unforeseen conditions, homeowner irrigation, or other circumstances. Where drains are constructed during grading, including subdrains, the locations/elevations of such drains should be surveyed, and recorded on the final as-built grading plans by the design engineer. It is recommended that the above be disclosed to all interested parties, including homeowners and any homeowners association. Erosion Control Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to Mr. and Mrs. WIiiiam Lynn 6575 Blackrail Road, Carlsbad Flle:e:\wp9\3400\3460b. fcr2 GaoSoil.t;. lne. W.O. 3460-81-SC September 14, 2004 Page 15 DETAILS N . T . S . SCHEMATIC TOE DRAIN DETAIL Drain Pipe Drain May Be Constructed Into, or at, the Toe of Slope Permeable Mater! • 12" Minimum 24" Minimum NOTES: 1.) Soll Cap Compacted to 90 Percent Relative Compaction. 2.) Permeable Material May Be Gravel Wrapped In Filter Fabric (Mlrafl 140N or Equivalent). 3.) 4-lnch Diameter Perforated Pipe (SOR 35 or Equivalent) with Perforations Down. 4.) Pipe to Maintain a Minimum 1 Percent Fall. 5.) Concrete Cutoff Wall to be Provided at Transition to Solid Outlet Pipe. 6.) Solid Outlet Pipe to Drain to Approved Area. 7.) Cleanouts are Recommended at Each Property Line. SCHEMATIC TOE DRAIN DETAIL DETAIL4 Geotechnical • Coastal • Geologic • Environmental TOPOFWALL~ RETAINING WALL~ FINISHED GRADE \ DETAILS N.T.S . 2:1 SLOPE (TYPICAL)~ BACKFILL WITH COMPACTED NOTES: _ _ _ _ _ 12" MIN · 12 NATIVE SOILS 1.) Soll Cap Compacted to 90 Percent Relative Compaction. 2.) Permeable Material May Be Gravel Wrapped In FIiter Fabric (Mlrafi 140N or Equivalent). 3.) 4-lnch Diameter Perforated Pipe . (SDR-35. of Equivalent) with MIRAFI 140 FILTER FABRIC Perforations Down. OR EQUAL 3/4" CRUSHED GRAVEL 4" DRAIN 4.) Pipe to.Maintain a Minimum 1 Percent Fall. 5.) Concrete Cutoff Wall to be Provided at Transition to Solid Outlet Pipe. 6.) Solid Outlet Pipe to Drain to Approved Area. 7.) Cleanouts are Recommended at Each Property Line. 8.) Compacted Effort Should Be Applied to Drain Rock. SUBDRAIN ALONG RETAINING WALL DETAIL NOTTO SCALE SUBDRAIN ALONG RETAINING WALL DETAIL DETAIL 5 Geotechriical • Coastal • Geologic • Environmental providing hay bales and silt fences for the temporary control of surface water, from a geotechnlcal viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum distance of 1 o feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or non-erosive devices that will carry the water away from the house. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurr.ing in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Mr. and Mrs. WIiiiam Lynn 6575 Blackrall Road, Carlsbad Flle:e:\wp9\3400\3460b.fcr2 CeoSoils. lne. W.O. 3460-81-SC September 14, 2004 Page 18 Site Improvements Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench, and retaining wall backfills. TIie Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such. as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance o{ any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street and parking areas and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching Considering the nature of the onsite soils, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose_ (typiqally 25 to 45 degrees) may be necessary and Mr. and Mrs. WIiiiam Lynn 6575 Blackrail Road, Carlsbad File:e:\wp9\3400\3460b. fcr2 GeoSoils. lne. W.O. 3460-B1-SC September 14, 2004 Page 19 should be anticipated. All excavations should be observed by one of our representatives and minimally conform to CAL-OSHA and local safety codes. Utility.Trench Backflll 1. All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-lnch to 18-inch) under-slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded Into place. Observation, probing and testing should be provided to verify the desired results. 2. Exterior trenches adjacent to, and within areas extending below a 1 :1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to verify the desired results. 3. All trench excavations should conform to CAL-OSHA and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing. or grade beam in accordance with the recommendations of the structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: • • • • During grading/recertification . During significant excavation (i.e., higher than 4 feet) . During placement of subdrains, toe drains, or other subdrainage devices, prior to placing fill and/or backfill. After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Mr. and Mrs. WIiiiam Lynn 6575 Blackrall Road, Carlsbad Flle:e:\wp9\3400\3460b.fcr2 W.O. 3460-81-SC September 14, 2004 Page 20 GeoSoils. lne. • Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During slope construction/repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. • When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and · clear documentation of site work, and/or to comply with code requirements. • GSI should review project sales documents to homeowners/homeowners associations for geotechnical aspects, including irrigation practices, the conditions outlined above, etc., prior to any sales. At that stage, GSI will provide homeowners maintenance guidelines which should be incorporated into such documents. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc.; should review the· recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer/designer. The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and deflections in the various slab, foundation, and other elements in order to develop appropriate, design-specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer/designer should consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer/designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely Mr. and Mrs. WIiiiam Lynn 6575 Blackrall Road, Carlsbad Flle:e:\wp9\3400\3460b.fcr2 GeoSoils. lne. W .O. 3460-B1-SC September 14, 2004 Page 21 that some, more restrictive details will be required. If the structural engineer/designer has any questions or requires further assistance, they should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate potential distress, the foundation and/or improvement's designer should confirm to GSI and the governing agency, in writing, that the proposed foundations and/or improvements can tolerate the amount of differential settlement and/or expansion characteristics and design criteria specified herein. PLAN REVIEW Final project plans should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. Mr. and Mrs. WIiiiam Lynn 6575 Blackrall Road, Carlsbad Flle:e:\wp9\3400\3460b. fcr2 GeoSoils. lne. W.O. 3460-81-SC September 14, 2004 Page22 We appreciate this opportunity to be of service. If you have any questions, please call us at (760) 438-3155. Respectfully submitted, GeoSolls, Inc. 4-:&•A Ryan Boehmer Staff Geologist RB/ JPF /DWS/jk Attachments: Table 1 -Field Density Test Results Plates 1 and 2 -Field Density Test Location Maps Distribution: (4) Addressee Mr. and Mrs. WIiiiam Lynn 6575 Blackrall Road, Carlsbad Flle:e:\wp9\3400\3460b. fcr2 GeoSoils. Jne. W.O. 3460-81-SC September 14, 2004 Page23 Table 1 FIELD DENSITY TEST RESULTS 8/5/04 8/5/04 West Of Parcel 2 Drlvewa 8/11/04 N. Side of Parcel 4 8/11/04' S. Side of Parcel 4 32 8/13/04 · House Pad 33 8/13/04 House Pad LEGEND: FG = Finish Grade · ND = Nuclear. D~nsometer Mr. and Mrs. WIiiiam Lynn 6575 Black Rail Road File: C:\excel\tables\3400\3460b.fcr 372.0 10.2 365.0 9.9 366.0 9.6 FG 10.4 FG 10.8 GeoSoils. lne. 119.4 120.9 . 121 .4 125.2 125.5 91 .6 W.O. 3460-8 -SC August 2004 Page 1 I I I I I I i I I> • . ... ... ..• I>: ~ -~ •. • > ~ •t> : • •• •. .•. ~: ...... I> • z "' ::i ::1 F "' I~ ,OE "• ... --~ 's)~ --.7~ Nj6°58'25"W X-32 /:XISTING GARAGE X-30 r I I I "' _____ J a: ~ af OUTLINE Of F1RST FLOOR. Ff:~77 .01 (No PAO, STEM WALL CONSTRUCTION W/FOOTINGS @ NA l\JRAL GRACE)) ~ ~g11,GE PARCEL 4 Qt +217 +-216 af r l l ~ .. • ·.11.• •. • • .. • ~,~ ~~-\t 0 0 0 0 ~~1-1 ~ \ ·•·tt I ::._ · \1J-t:x1s1. o· CHAIN LINK\FENCE TO • . BE RE!'I..ACEO WITH 1.21 FENCE ~ j::: ~ ~ I:) 09 0 0 ·• 4·1; Qt ~~filU==----~O'• I \ .-·.. , ~ , ~ 1 c,·~. : . ~ ~ I "' ~-+-c-tttt---~o· ~o·- 1• ARIES---- .I "' N 86°59'01." W 106.52·/ _p ,,,.,_., ... ~, .. / ✓ ~ 0 e ,I ·• \I l + + r ==il 0- 0 LEGEND ARTIFICIAL FILL PLACED IJ-lDER THE PURVIEW OF THIS REPORT QUATERNARY TERRACE DEPOSITS APPROXIMATE LOCATION OF GEOLOGIC CONTACT APPROXIMATE LOCATION OF FIELI @ © @ CU/-' 04-Zb GRAPHIC SCALE /0 ? 5 ~:llNIC•:..IIICI ~ 10 i r ( INFffT) I lloCH: 10 FT. /IIJICA TES RIGHT 4•WAY GRANTED TO SN' 0 EGO GAS AMJ 8 /:lEC Tl/JC COMF,,_Y •o C"'57«T, OPfRATE MANTA#/ -R£1UCE A I.IE CF P<US Fa/ T,E TR,WSHISSICN AJIJ OISTTl/8UTKIV CF l'LECTR<ITY PER 0cc. 1/ECCIIDEO J/Jl//966 AS fll.E No. 51,/44, O.R. (To REMAIN) /1,()/CATfS l:ASBENT GRA/ffED TO PACIFIC TB.B'IOE -Tf!EG!Wf{ Fa/ P,JJUC i1urr l'IR'OS!S PER 0cc. RECOl/lJED Ul2//96t AS Fu No. 67864, O.R. (T., R<J<AI/) f'Roi>asEO Sflff/1 l:ASE!'EHT TO T/f CITY CF CAI/I.S8AD. /NtJtcA TES EASBIENT CRAJ;TED TO TIE C. TY CF CAll.S8AD Fa/ l'IJJLJC STREET AID PI.S..IC 40 I UC~/TY Pl.I/POSES F£R 0cc. R£C(11()f0 I2/l6/l997 AS FIi.£ No. !997.(i658/JOO, 0.R. (TO REMAN) --PAPCEI. 2, PH /9Lll ---+--- (/:XIST. L YW i?fl«NCE) r XISTING GRACE ~ VARIES -I' M1~ ----CONST. 6' MAX. RET. WALL ~ ·. t,' ::lift'IACY & SAf?TY F9K'E ON P.L. ROPOSEO DRIVEWAY l,_ __ ,__. SECTION( A Nor ro ScAI.E ' P•'<CEI. L .f lt,t(X RJ~ RoAO ·-1-: ~ 'l l / ,-f-: BENCHMARK: tJ □ CfSCIIIPTIIX OC-i/179 O sc SET IN Ktsr E,c, CF SroTH HEADWW. LOCATION: OF i'4" FKP 0.4 MIU' /:AST OF IN"EllSECTKJN CF U COSTA A~. AHi) S•xc;;r RDAD. REa:f//JS FJK:H: Ca.NTY CF SAIi DE.O. OEPT. CF 1'1.5.IC W~ RE!'t::RT SVO/i/6-i!l,I0 5185 l:LEYAT/ai: /J.87 OATIJ'I: M.S.L. SECTION( B Nor ro SCALE Rll'ERSID£ CO. 'C. ORA.l'l"Gt; CO. SA.V D/£GO CO. FIELD DENSITY TEST LOCATION MAP Plate 1 E#§.INEER OF WORK ·X-x-x-x--x-x-x-- w.o. 3480-81-SC I DATE: 9/04 SCALE: 1"=10' IILB Engineering Profissio11al Civil Engineers and Land S11ro~yors MICHAB. L. 8EJ6I. RC£ J789J REG. l:ilPIIIES JIJl/tJS "AS-BUILT" /JJOf1£L5!16H ~C.E. J78'/J. ~,. E'1'. J/Jv05 ~ o:m= · 600 South M(hOMII Oriw, Suite E. Eacondida, CA 92029 Phone 760 741-~77 FAX 760 897-2165 E-Mal : MLSennhClpo.,+!!M,:~ 0,,, 0ATE •!-I I I I I I I 1m1 City 2._~sbad IQJ f\or~F01t: I I I I I I I 11::~:: ~,,.,~ 1 LYNN RESIDENCE PARCEL 4, PH 19!1/ OATE I .NITW.. £1ite1Ei?CT ii~ REVISION DESCRIPTION 9AI! I N,TJM. I JA rt I IN'rw. VT'lll~t.ct Cir,f,,IIJ'1:)U .. J'IJ.'1#6~ Cl€UEOB~ ,.~a,- ~ UC ·t lL ,,, I ', { "-1 ~s~Y-~0 ~~~ I , __ _ I I I I ~ I ~ C I 'O ~ z ij ~ ''-,."~ ' . " _,,,_. ,. '+'---x->< <:: a.: -q; / Lot 7 (Pod.J55.0) - ~ I~- - TRI TON WAY N86'58'Jrw 266.91' """=, ,.,, ... lloln fW Owg. No. 410-6 ~~e.. .~ -f. (Pod .155.2) c.r. 98-18, I I I I I I ,.J I I Existng G<rog. ~ I Lot 5 (Pod .155.2) Map No. 14043 + I I 1:1) r-)::,. ~ . i~ I~ : ·ti ,. ll ~\ ~tn +~ ,11 l~ 1: ;~ .. ~ N .... :IE \ · ...... \/ r J RJV£11SIDl1 aJ. IC:. OIIANCtaJ. SA.,Y Dl£C() CO. ·1 [ Lot 1 L1 t I I.Ill J FIELD DENSITY TEST LOCATION MAP Plate2 • !fil l-~ ' I ~l i T ,,/ 0 0 + + 0 re--~ .. ~s w.o. 3460-81-SC I DATE: 9/04 I SCALE: 1"=20' 0.5' X J' BERM (ON PL TURF AREA) Not fo ~ It/ow Strj, p..-Oetal --fswl....1 fJGdJ ~-- SEE PLATE I FOR LEGEND Turf Area {Drou;it Resistant Gro~ Mil. 2• helghl) ·-,t.i,g()Qde 2 ~ V ,, : llrMwoy •/1 0 6" Q.rtJ See Detol Sheet 2. llrMwoy •/2 0 6" QJrbs See Detol Sheet 2. '- Const Wood f' ence or. Blade Wal w/4" Oio. w.epholes O 4' CI.C. £fmi....1 .I !ml: Rql Rqqd Not To Const 6' Max. Rel EASEMENT NOTES GRAPHIC SCALE 10 20 ~ 2 1r7 8-:, mf •.1. !..,, •~l"t- (F) l J @ lndicota Right-of-Way 'Tf11lltld lo Son Diego Cos tnd ct El«lric Company ;. t con:stroct op,rate mointoin tnd ~"" o 1;,e of po/a for the 1ron.,,.,,~=-ond dislTl,ution of •«lridty p..-Doc. rsccrd«J J/J1/1966 as R, No. ~ ~1#, O.R. (To R.,,,,;,) @ /ndict11a cosem«II 'Tf11lltld to Pacific T•t/f)lloM tnd T~ for Public Utlity purpo!J9$ per Doc. reccrded 4/22/1966 as R• No. 67864, O.R. {To Remoin) @ Propo#d S.--f_.,t to the City of Corlsbod. J I 1 j 1 Jmli.F§f!) ft -~· I _.., @ /ndict11a __,t 'Tf11lltld to 1h11 City of Corl3bod for pwlic strfel "1d pwlic utlity ,,.,,,,,_ p..-Doc. recorded 12/26/1997 as fie No. 1997-0658900, O.R. (To Remain) BENCHMARK: 0 o.si:ij,&n· OC-01'19 Disc S.t ;, West end of South H.adrtal of 24"Ra' Location: 0.4 Mh fast ol lntr.1eetion of La CM/o A.._ ENGINEER OF WORK UidHJdl L &na,, RC£ J"l89J Reg. bpia J/J1/o5 Oat11 ·X-x--x-x-,nd Sa,tony Rood. 'll'LB R«cr<b FromCovnty of Son o;.g,,. ~l of public lllris!JI Report S'tfJ106-0l, I0/15/85 E . "AS-BUILT" I ng1neer1ng °""'1tion: TJ.87 Datum: M.SL P,efessional Ciiil E.n.r,intm and l.J111d S11myon - IOO Soutll Ao,-0rM, S.lte E. ~ CA 92029 Phone 790 7♦1-J&TT FAX 790 -7-2195 E-...-.......--, ~ o.,, I ,=• rr-I I I I I I I ICTJI City c:!,~bad l(]J •o...,--c,,,,w-,-,r. LYNN MINOR SUBDIVISION t---+--t--------------+----i--+--+--tl IIS' o,-oi Sheet J .:. Retise p, REVISION OESCRIPT/0N 1~:!!!f!el~~ -1 ':~IIE!i II l'n,j,dNo. HS 01-04 -1 11 :6i: I I I ~ I I □ Geotechnlcal • Geologic • Environmental 5741 Palmer Way • Carlsbad, California 92008 • (760) 438-3155 • FAX (760) 931-0915 Mr. and Mrs. WIiiiam Lynn 6575 Black Rail Road Carlsbad, California 92009 October 7, 2004 W.O. 3460-B2-SC Subject: Foundation Plan Review, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California References: 1. "Foundation Plan, Lynn Residence, Black ·Rall Road, Carlsbad, California," Project No. 043272, Dated August 13, 2004, Sheets S-2, S-1A, and D-3, Prepared by Engineering Design Group. 2. "Final Compaction Report of Grading, Building Pad Area, Parcel 4, 6575 Black Rall Road, Carlsbad, San Diego County, California," W.0. 3460-B1-SC, dated September 14, 2004, by GeoSoils, Inc. Dear Mr. Lynn: In accordance with your request, GeoSoils, Inc. (GSI) has performed a geotechnical review of the referenced foundation plans for the proposed subject project. Unless superceded in the text of this report, recommendations presented In Reference No. 2 are considered valid and applicable. · The foundation plans, notes, and details (see Reference No. 1) have been reviewed by this office and appear to be in general conformance with the recommendations provided by this office and presented in the referenced report by GSi {see Reference No. 2), from a geotechnlcal viewpoint. · · The conclusions and recommendations presented herein are professional opinions. These opinions have been derived In accordance with current standards of practice and no warranty Is expressed or Implied. Standards of practice are subject to change with time. GSI assumes no responsibility for work, testing or recommendations performed or provided by others. We appreciate this opportunity to be of service. If you have any questions pertaining to this report, please contact us at (760) 438-3155. Respectfully submitted, GeoSolls, Inc. ~n~E. Staff Geologist BEV/DWS/JPF/jh Distribution: (4) Addressee Mr. and Mra. WIiiiam Lynn Parcel 4, 6575 Black Rail Rd., Carlsbad Flle:e:\wp9\3400\3460b2.fpr Ge.Soils. lne. W.O. 3460-82-SC October 7, 2004 Page2 . GEOTECHNICAL UPDATE, PARCEL 1 OF PARCEL MAP 19411, APN 215-070-39 CA~LSBAD, $AN DIEGO COUNTY, CALIFORNIA · FOR A&E CONSTRUCTION SERVICES 538_FRONT STREET EL CAJON, CALIFORNIA 92020 W.O. 6087.-A-SC JUNE 16, 2010 Geotechnlcal • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com A&E Construction Services 538 Front Street El Cajon California 92020 Attention: Mr. Joe Esposito June 16, 201 0 W.O. 6087-A-SC Subject: Geotechnical Update, Parcel 1 of Parcel Map 19411, APN 135-030-55, Carlsbad, San Diego County, California Dear Mr. Esposito: In accordance with a request and authorization, GeoSoils, Inc. (GSI), has prepared this report for the purpose of updating our previous referenced reports (see Appendix A), in light of current standards of practice. This update is based on visual observations made during a site reconnaissance, performed on June 15, 2010, a review of the conceptual plans provided by the client, and GSl's previous reports (see Appendix A). Recommendations contained in the previous reports, which are not specifically superceded by this review, should be properly incorporated into the design and construction phases of site development. SITE CONDITIONS/PROPOSED DEVELOPMENT The site consists of an irregular-shaped property, located on the northwest comer lot of the proposed "Lynn Minor Subdivision," west of Black Rail Road, in Carlsbad, San Diego County, California. Based on our previous reports (see Appendix A), the site was rough graded sometime around January 13, 2004, and was generally completed on January 29, 2004. It is our understanding that proposed construction will consist of a lot split and the construction of two, two-story single-family residences on the lots. Cut and fill grading techniques would be utilized to create design grades for the proposed split-level single- family residential structures, with slab-on-grade floors and continuous footings, utilizing wood-frame and/or masonry block construction. Building loads are assumed to be typical for this type of relatively light construction. The need for import soils is unknown. Sewage disposal for the site is anticipated to be tied into the regional system. PLAN REVIEW A review of the ±20-scale conceptual grading plan (unknown author and date), it appears that the lower levels of both proposed residences will have cut-fill transitions. The northerly residence pad grade for the basement is shown as 361 feet Mean Sea Level (MSL), which indicates on the west side, there will be about 3 to 4 feet of engineered fill below this elevation; in contrast on the east side of the basement, there will be some cut and/or up to about a foot of engineered fill below this elevation, which would result in a non-uniform subgrade. Additionally, retaining walls supporting outside improvements as well as the superjacent split levels are proposed. Thus, the two upper pads on the proposed northerly residence will be fill, also indicating non-uniformity of subgrade for the foundations, walls, and slabs-on-grade of the structure as a whole. The sou~herly proposed residence will have a cut-fill transition through a portion of the lower level, with most of the lower level proposed as cut. Similar to above, retaining walls supporting outside improvements as well as the superjacent split level are proposed. Again, the two upper pad on the proposed southerly residence will be fill, also indicating non-uniformity of subgrade for the foundations, walls, and slabs-on-grade of the structure as a whole. SEISMIC SHAKING PARAMETERS Based on the site conditions, the table below summarizes the site-specific design criteria obtained from the 2007 California Building Code ([2007 CBC], California Building Standards Commission [CBSC], 2007), Based on the 2006 International Building Code (IBC), Chapter 16 Structural Design, Section 1613. We used the computer program Seismic Hazard Curves and Uniform Hazard Response Spectra, provided by the United States Geological Survey (USGS, 2009). The short spectral response uses a period of 0.2 seconds. Site Class Spectral Response -(0.2 sec), s. Spectral Response -(1 sec), S1 Site Coefficient, F. Site Coefficient, Fv Maximum Considered Earthquake Spectral Response Acceleration (0.2 sec), SMs Maximum Considered Earthquake Spectral Response Acceleration (1 sec), ~1 A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. D 1.49g 0.56g 1.0 1.5 1.49g 0.84g Table 1613.5.2 Figure 1613.5(3) Figure 1613.5(4) Table 1613.5.3(1) Table 1613.5.3(2) Section 1613.5.3 (Eqn 16-37) Section 1613.5.3 (Eqn 16-38) W.O. 6087-A-SC June 16, 2010 Page2 5% Damped Design Spectral Response Acceleration (0.2 sec), Sos 0.99g Section 1613.5.4 (Eqn 16--39) 5% Damped Design Spectral Response 0.SSg Section 1613.5.4 Acceleration (1 sec), S01 (Eqn 16-40) Distance to Seismic Source (Rose Canyon fault) Upper Bound Earthquake (Rose Canyon fault) Probabilistic Horizontal Site Acceleration ([PHSA] 10% probability of exceedance in 50 years) I* International Conference of Building Officials (ICBO, 1998) 5.6 mi. (9.0 km) Mw6.9* 0.19g Conformance to the criteria above for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur in the event of a large earthquake. The primary goal of seismic design is to protect life, not to eliminate all damage, since such design may be economically prohibitive. PREVIOUS LABORATORY TESTING Previous laboratory test results by GSI which are relevant to the currently proposed development are summarized below: Expansion Index As indicated in GSI (2004d), the expansion index of a representative sample of soil exposed near finish grade is less than 20. According to Table 18A-I-B of the 2001 CBC (International Conference of Building Officials [ICBO], 2001), the expansion potential of the tested soil is classified as very low expansive. This definition is not in the 2007 CBC, however is utilized herein as a classification tool. Maximum Density Testing As indicated in GSI (2004d), the laboratory maximum dry density and optimum moisture content for the major soil type encountered during grading were determined according to test method ASTM D 1557. The following table presents the results: A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, Ine. W.O. 6087-A-SC June 16, 2010 Page 3 A-Orange Brown, SILTY SAND 131.0 9.0 B -Gra Brown SIL TY SAND Im ort 137.0 9.0 Saturated Resistivity, pH. and Soluble Salt A representative sample of the site materials has been previously analyzed for corrosion, soluble sulfates, and chlorides (GSI, 2002a). Laboratory testing indicates that site soils generally have a negligible sulfate content (54 mg/kg) and a non-detectible chloride content. Per Table 4.2.1 of ACI 318-08 (per the 2007 CBC [CBSC, 20071), the site soils are not applicable to special concrete design for soluble salts. Corrosion testing (pH/saturated resistivity) indicates that the site soils are slightly acid (pH = 6.5) with respect to soil acidity/alkalinity and are moderately corrosive to exposed ferrous metals when saturated (saturated resistivity = 2,900 ohm-cm [California Highway Design Manual, 20061). Alternative testing methods and additional comments should be obtained from a qualified corrosion engineer with regard to foundations, piping, etc. PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS Geotechnically, the subject site is in essentially the same condition as it appeared during the preparation of our previous report (GSI, 2004d), with the exception that the surficial fill is weathered, and somewhat dry to loose, as a result. Based upon our review of the current conceptual plan provided by you, the previous GSI reports (Appendix A), and geologic and engineering analyses, the proposed development of this site is geotechnically feasible, provided our recommendations are properly implemented. It is our understanding that the proposed lot split will require regrading the existing lot to proposed grades. Therefore, the referenced geotechnical reports are generally considered relevant and applicable to the proposed construction. Recommendations contained in the previous reports (see Appendix A), which are not specifically superceded by this review, should be properly incorporated into the design and construction phases of site development. It should be noted, thatthe 2007 California Building Code ([2007 CBC] California Building Standards Commission [CBSC], 2007) indicates that removals of unsuitable soils be performed across all areas under the purview of a grading permit, not just within the influence of the residential structure. Relatively deep removals may also necessitate a special zone of consideration, on perimeter, confining areas, such that this potential zone is approximately equal to the depth of removals, if removals cannot be performed offsite. Thus, any settlement-sensitive improvements (perimeter walls, curbs, flatwork, etc.), constructed within this perimeter zone may require deepened foundations, reinforcement, A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page 4 etc., or will retain some potential for settlement and associated distress, if not properly mitigated during grading. The recommendations in the following sections should be properly incorporated into project planning, design and construction. Earthwork Recommendations General Remedial earthwork will be necessary for the proper support of planned fill and proposed settlement-sensitive improvements. All grading should conform to the guidelines presented in Appendix J of the 2007 CBC (CBSC, 2007), the requirements of the City of Carlsbad, and the Grading Guidelines presented in Appendix B of this report ( except where specifically superceded in the text of this report). In case of conflict, the more onerous code or recommendations should govern. Prior to grading, a GSI representative should be present at the pre-construction meeting to provide additional grading guidelines, if needed, and to review the earthwork schedule. During earthwork construction, all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representative(s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and, if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act (OSHA), and the Construction Safety Act should be met. It is the responsibility of the onsite general contractor and individual subcontractors to provide a safe working environment. GSI does not consult in the area of safety engineering. Existing Vegetation and Debris All existing vegetation and debris (concrete, degraded storm water BMPs, etc.) within the influence of proposed development should be removed and properly disposed. Existing Building Pad and Private Drive Owing to almost six years of remaining fallow, the upper 1 foot of the existing, weathered fill soils exposed at the surface of the building pad and the private drive should be removed, moisture-conditioned to at least the soil's optimum moisture content, and then be mechanically compacted to at least 90 percent of the laboratory standard (ASTM D 1557), to 5 feet outside of any settlement-sensitive improvements. A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 · Page 5 Existing Fill Slopes Sparse to locally abundant rodent burrows were observed on the fill slope descending from the building pad. Prior to remedial earthwork, a contractor specializing in rodent abatement should observe the site conditions and provide recommendations for mitigation as necessary. Following rodent abatement, the existing fill materials on the slope surface should be scarified 6 to 12 inches, moisture conditioned to the soil's optimum moisture content, and then be recompacted to at least 90 percent of the laboratory standard. The slope surface should be reconstructed to its original planned gradient of 2:1 (h:v). In addition, the observed scouring at the toe of the south-facing fill slope should be scarified 6 to 12 inches, moisture conditioned to at least the soil's optimum moisture content, and then returned to it original graded condition with compacted fill materials. Rodent control will need to be maintained over the life of the project. New Fill Slope (South Portion of Turf Area) Based on the remedial earthwork documented in GSI {2004d), generally, cut grading operations took place and limited fill was placed along the proposed road. Therefore, remedial removal and recompaction of unsuitable soils (i.e., undocumented fill, topsoil/colluvium, weathered terrace deposits/fill) in this area will be necessary for proper support. Based on a review of GSI (2002b) remedial removal excavations may be on the order of 3 or 4 feet below the existing grade. However, locally deeper removal excavations may be necessary to remove unsuitable soils, and should be anticipated during grading. Remedial removal excavations should be completed below a 1 :1 (h:v) projection down from the toe of the proposed slope. A minimum equipment width keyway should then be established by providing at least 2 feet of embedment into competent terrace deposits at the toe of the keyway and sloping the bottom of tl:te keyway at least 2 percent from toe to heel. Prior to placing fill in the keyway, the bottom should be scarified at least 6 inches, moisture conditioned to the soil's optimum moisture content, and then be recompacted to at least 90 percent of the laboratory standard (ASTM D 1557). Fill should then be placed in thin lifts, moisture conditioned to at least optimum moisture content and then be mechanically compacted to at least 90 percent of the laboratory standard (ASTM D 1557). During fill placement for construction of the new slope, unsuitable soils should be benched to expose competent terrace deposits or unweathered fill. OVEREXCAVATION/NON-UNIFORM SUBGRADE In order to provide for the uniform support of the planned improvements, a minimum 3-foot thick fill blanket is recommended for the graded pads. Any cut portion of the pads for the residences should be overexcavated a minimum 3 feet below finish pad grade and at least 5 feet outside of the building footprint. Areas with planned fills less than 3 feet should be A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 o Pages overexcavated in order to provide the minimum fill thickness. Based on GSl's review of our prior report (GSI, 2004d), the proposed lower floor levels will need to be overexcavated a minimum of 3 feet below proposed grade for both planned residences, if remedial removals do not penetrate to these elevations. Fill thickness should not exceed a ratio of 3:1 (maximum to minimum) across the building areas. The intent of this recommendations is to have a minimum fill thickness of at least 2 feet below all footings. COMPACTION STANDARDS In light of the sandy onsite soils, with low fines content (cohesion of less than 250 pounds per square foot [psf] on average, and proposed buildings split level construction, it is recommended that fill or backfill placed within the building footprint, or within 5 feet from the buildings or retaining walls, that the compaction standard should be increased to 95 percent of ASTM D-1557, at or above optimum moisture content, to mitigate static and seismic ·differential settlement. This condition should be readily achievable owing to the sandy materials onsite. PRELIMINARY FOUNDATION RECOMMENDATIONS In the event that the information concerning the proposed development plan is not correct, or any changes in the design, location or loading conditions of the proposed structure are made, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. The information and recommendations presented in this section are not meant to supersede design by the project structural engineer. Upon request, GSI could provide additional input/consultation regarding soil parameters, as they relate to foundation design. The following preliminary foundation design and construction recommendations are based on laboratory testing and engineering analysis of orisite earth materials by GSI. Previous laboratory testing (GSI, 2004d) indicates that the expansion potential of near-finish grade soils are generally in the very low (E.I. 0 to 20 range) range according to Table 18-1-8 of the 2001 CBC (ICBO, 2001) with a Pl less than 15. Therefore, foundations do not need to comply with Section 1805A.8 of the 2007 CBC (CBSC, 2007) to mitigate expansive soil effects. However, due to regionally pervasive paleoliquefaction features, GSI {2002b) recommended the use of post-tensioned slabs for support of any residential structure constructed on these lots. The recommendations provided herein consider that condition. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page7 POST-TENSIONED SLAB AND FOUNDATIONS General The information and recommendations presented in this section are not meant to supersede design by a registered structural engineer or civil engineer familiar with post-tensioned slab design or corrosion engineering consultant. The follo~ing recommendations for the design of post-tensioned slabs have been prepared in general compliance with the requirements of the recent Post Tensioning lnstitute's (PTl's} ·publication titled "Design of Post -Tensioned Slabs on Ground, Third Edition" together with it's subsequent addendums. From a soil expansion/shrinkage standpoint, a common contributing factor to distress of structures using post-tensioned slabs is a "dishing" or "arching" of the slabs. This is caused by the fluctuation of moisture content in the soils below the perimeter of the slab primarily due to climatic and seasonal changes, and the presence of expansive soils. When the outside soil environment surrounding the slab has a higher moisture content than the area beneath the slab, moisture tends to migrate underneath the slab edges to a distance beyond the slab edges known as a moisture variation distance, and cause the slab edges to lift. Conversely, when the outside soil environment is drier, the moisture regime is reversed and the soils underneath the slab edges lose their moisture and shrink. This process leads to dropping of the slab at the edges, which leads to what is commonly referred to as the center lift condition. Therefore, post-tensioned slabs should have sufficient stiffness and rigidity to resist excessive bending due to non-uniform swell and shrinkage of subgrade soils, particularly within the moisture variation distance, near the slab edges. Design 1 . An allowable bearing value of 2,000 psf may be used for design of footings which maintain a minimum width of 12 inches (continuous) and 24 inches square (isolated), and a minimum depth of embedment at least 12 inches into properly engineered fill. This embedment does not include the concrete floor slab or slab underlayrnent inside the building nor the upper few inches of landscape soil on the exterior of the building. The bearing value may be increased by one-third for seismic or other transient loads. This value may also be increased by 20 percent for each additional 12 inches in depth to a maximum of 2,500 psf for foundations embedded into engineered fill. No increase in bearing value for increased footing width is recommended. 2. For lateral sliding resistance, a 0.25 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load for foundations embedded in fill. Foundations embedded into formation, a value of 0.4 may be used. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 o Page a 3. Passive earth pressure may be computed as an equivalent fluid having a density of 200 pcf with a maximum earth pressure of 2,000 psf. 4. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 5. All footings should maintain a minimum 7-foot horizontal distance between the base of the footing and any adjacent descending slope, and minimally comply with the guidelines depicted on Figure 1805A.3.1 of the 2007 CBC (CBSC, 2007). Stiffened· Slabs For a typical slab designed with interior ribs, or stiffeners, the slab should be at least 5 inches thick for soils with a very low expansion potential. The ribs should be provided in both transverse and longitudinal directions. The interior rib spacing and depth should be provided by the project structural engineer responsible for the design of the post-tensioned slabs. The perimeter beams, however, should be embedded at least 12 inches for soils with a very low expansion potential. The embedment depth should be measured downward from the lowest adjacent grade surface to the bottom of the beam. Uniform Thickness Foundations (UTF) The foundation slab thickness should be designed· by the project structural engineer. However, if a UTF foundation is used, a minimum thickness of 6 inches should be incorporated into the foundation. Pre-Soaking Due to the very low expansion potential of the tested onsite soils, no specific pre-soaking program appears warranted. However, for very low expansive soils, the moisture content of the subgrade soils should be 1 to 2 percentage points above the optimum moisture content to a depth of 12 inches below grade, prior to pouring concrete. Soll Support Parameters The recommendations for soil support parameters have been provided based on typical soil index properties for soils ranging from very low to low in expansion potential. The soil index properties are typically the upper bound values based on our experience and practice in the southern California area, and are provided in the table below: A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 o Page9 Suction Compression Index-Swell 5.0 feet Suction Compression Index-Shrink 3.5 feet Upper Bound Liquid Limit (Ll.) 35 Upper Bound Plasticity Index (Pl) 20 Upper Bound Percent Fines (-#200) 30 Upper Bound Percent Clay 15 Soll Fabric Factor (Ff) 1.0 Modified Unsaturated Diffusion Coefficient -a' Swell (Edge Lift) 5.00 E-03 Modified Unsaturated Diffusion Coefficient-a' Shrink (Center Lift) 5.02 E-03 Equilibrium Suction pF 3.9 Thornthwalte Index 0 to -20 Based oo the above, the recommended preliminary soil support parameters are tabulated below: em center lift 9.0feet em edge lift 5.2feet Ym center lift 0.5 inch 0.6 inch The coefficients are considered minimums and may not be adequate to represent worst case conditions such as adverse drainage and/or improper landscaping and maintenance. The above parameters are applicable provided structures have positive drainage that is maintained away from structures. In addition no trees with significant root systems are planted within 15 feet of the perimeter foundations. Therefore, it is important that information regarding drainage, site maintenance, trees, settlements, and effects of expansive soils be passed on to future owners. The values tabulated above may not be appropriate to account for possible differential settlement of the slab due to other factors, such as excessive settlements. If a stiffer slab is desired, higher values of Ym may be recommended. A&E Construction APN 215-070-39, <;:arlsbad Flle:e:\wp9\6000\6087a.gun CeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 10 Settlement In addition to designing slab systems (post-tension or other) for the soil conditions, described herein, the estimated settlement and angular distortion values that an individual structure could be subject to should be evaluated by a structural engineer as differential settlement of 1 inch over 40 feet. Footing Setbacks All footings should maintain a minimum 7-foot horizontal setback from the base of the footing to any descending slope and minimally comply with the guidelines depicted on Figure 1805A.3.1 of the 2007 CBC (CBSC, 2007). The setback distance is measured from the footing face at the bearing elevation. Footings constructed on the existing fill slope should be deepened below the creep zone (see the "Top-of-Slope Walls/Fences/Improvements" section of this report). Footings adjacentto unlined drainage .swales should be deepened to a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1 :1 projection from the heel of the wall. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances. Alternative Foundation Design for Mitigation of Paleoliguefaction Features As an alternative to post-tension foundations, the structural engineer may design a conventional-type foundation equipped with interconnected stiffening beams. The structural engineer should design the thickness of the concrete slab and reinforcing bar size and spacing to accommodate the edge and center distortions listed above. Perimeter footings should be at least 15 inches wide and be embedded a minimum of 18 inches below the lowest adjacent grade into engineered fill for two-story floor loads. Isolated pad footing should be connected in at least one direction, and be at least 24 inches square, and embedded at least 24 inches below the lowest adjacent grade into engineered fill. The minimum concrete slab thickness should be 5 inches. SOIL MOISTURE CONSIDERATIONS GSI has evaluated the potential for vapor or water transmission through the slabs, in light of typical residential floor coverings and improvements. Please note that typical slab moisture emission rates range from about 2 to 27 lbs/24 hours/1,000 square feet from a normal slab (Kanare, 2005), while typical floor covering manufacturers recommend about 3 lbs/24 hours as an upper limit. Thus, the client will need to evaluate the following in light of a cost v. benefit analysis, along with performance limitations. A&E Construction APN 215-070-39, Carlsbad Ale:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 11 Considering the anticipated typical water vapor transmission rates, floor coverings and improvements (to be chosen by the client) that can tolerate those rates without distress, the following alternatives are provided: 1. Concrete slabs should be a minimum of 5 inches thick. 2. Concrete slab underlayment should consist of a 10-mil to 15-mil vapor retarder, or equivalent, with all laps sealed per the 2007 CBC (CBSC, 2007) and the manufacturer's recommendation. The vapor retarder should comply with the ASTM E 17 45 -Class A or B criteria, and be installed in accordance with ACI 302.1 R-04 and ASTM E 1643. The 10-to 15-mil vapor retarder (ASTM E-17 45 - Class A) shall be installed per the recommendations of the manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). 3. Slab underlayment should consist of 2 inches of washed sand placed above a vapor retarder consisting of 10-to 15-mil polyvinyl chloride, or equivalent, with all laps sealed per the 2007 CBC (CBSC, 2007). The vapor retarder shall be underlain by 4 inches of. pea gravel (½ to ¾ subangular to angular clean crushed rock, o to 5 percent fines) placed directly on properly compacted subgrade soils, and should be sealed to provide a continuous water-resistant barrier under the entire slab, as discussed above. All slabs should be additionally sealed with suitable slab sealant. If the subgrade soils have a sand equivalent (SE) greater than 30, the 4-inch pea gravel layer may be omitted. 4. Concrete should have a maximum water/cement ratio of 0.50. This does not supercede the 2007 CBC (CBSC, 2007) for corrosion or other corrosive requirements. Additional concrete mix design recommendations should be provided by the structural consultant and/or waterproofing specialist. Concrete finishing and workablity should be addressed by the structural consultant and a waterproofing specialist. 5. Where slab water/cement ratios are as indicated above, and/or admixtures used, the structural consultant should also make changes to the concrete in the grade beams and footings in kind, so that the concrete used in the foundation and slabs are designed and/or treated for more uniform moisture protection. 6. Owners(s) and all interested/affected parties should be specifically advised which areas are suitable for tile flooring, wood flooring, or other types of water/vapor-sensitive flooring and which are not suitable. In all planned floor areas, flooring shall be installed per the manufactures recommendations. 7. Additional recommendations regarding water or vapor transmission should be provided by the architect/structural engineer/slab or foundation designer and should be consistent with the specified floor coverings indicated by the architect. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 12 Regardless of the mitigation, some limited moisture/moisture vapor transmission through the slab should be anticipated. Construction crews may require special training for installation of certain product(s), as well as concrete finishing techniques. The use of specialized product(s) should be approved by the slab designer and water-proofing consultant. A technical representative of the flooring contractor should review the slab and moisture retarder plans and provide comment prior to the construction of the residential foundations or improvements. The vapor retarder contractor should have representatives onsite during the initial installation. WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (typically Class 2 permeable filter material or Class 3 aggregate base) or native onsite materials (up to and including an E.I. of 50) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls and exterior walls, below grade/underground, should be water- proofed. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this rep9rt, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no.increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pcf; plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 1 o feet high. Design parameters for walls less than 3 feet in height may be superceded by City of Carlsbad standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 13 Level* 2 to 1 38 50 45 60 * Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without a slope for a distance of 2H behind the wall. ** As evaluated by testing, P.1. <15, E.I. <21, S.E. >30, and <10% passing No. 200 sieve. *** As evaluated b testin , P.I. <15, E.I. <5o,·s .E. >25. Seismic Surcharge for Retaining Walls For retaining walls that are over 6 feet in height, or within 6 feet or less of residences, that may impede ingress/egress, GSI recommends that the walls be evaluat!3d for a seismic surcharge (Section 1630A.1.1.5 of the 2007 CBC [CBSC, 2007]}. The site walls in this category should maintain an overturing Factor-of Safety (FOS) of about 1.2, when the seismic surcharge is applied. The seismic surcharge should be applied as a uniform load from the bottom of the footing (excluding shear keys), to the top of the backfill at the heel of the wall footing for restrained walls and an inverted triangular distribution for cantilever walls. This seismic surcharge pressure may be taken as 1 OH, where "H" is the dimension taken as the height of the retained material for the top of backfill. The resultant force should be applied at a distance 0.6H up from the bottom of the footing. For the evaluation of the seismic surcharge, the bearing pressure may exceed the static value by one-third, considering the transient nature of this surcharge. In addition to the above comments, GSI recommends that our field representative observe the temporary backcuts and footing excavations for the.walls. Temporary cuts for all wall installations should not exceed 1 :1 (h:v) inclinations, and should not be open for more than 90 days per cut, from start to finish. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1 , 2, and 3, present the back drainage options discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or ¾-inch to 1 %-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent}. For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 0 Page 14 (1) Waterproofing membrane -~ CMU or reinforced-concrete wall Structural footing or settlement-sensitive !mprovement Provide surface drainage via an engineered V-ditch (see civil plans for details) 2=1 (h=v) slope . . . :-. •' : .. ' .. : . •, .. . ·•.· . · ... • .. . · .-IJ ±12 Inches Proposed grade t - sloped to drain per precise civil drawings (5) Weep hole Footing and wall design by othera---~-1 (1) Waterproofing membrane. (2) Gravel= Clean, crushed, ¾ to 1½ inch. (3) Filter fabric: Mirafi 140N or approved equivalent. Native backfill 1=1 (h=v) or flatter backcut to be properly benched (6) Footing (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient sloped to suitable, approved outlet point (perforations down). (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Footing: If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. RETAINING WALL DETAIL -ALTERNATIVE A Detail (1) Waterproofing membrane (optional)-- CMU or reinforced:...concrete wall J ._ 6 lnchea 1 - (5) Weep hole Proposed grade sloped to drain per precise civil drawings ', \ \-(\ y,.<e--::~\ \ \-(\\1/-,. ... ,Y/\ \.,-\ \ ,'.::·<\~1//\ \ ,,\ \ \ Footing and wall design by others --£-----1 structural footing or settlement-sensitive improvement Provide surface drainage via engineered V-ditch (see civil plan details) 2:1 (h:v) slope '· .. : . ,\ . . . .. . . . ... · .... · ... . . : .. : ·:. :· : . ·:• .. . ........... , : . . .. . •, . .. . . . . : . \ .. ··=·.: .-.. :·.-.·:Slope·0r .. rever-< :· --:•_-:· .~-:· -: · __ ......... __ ·.·;. :·_, · :;·. __ .:_: .. ~ :~--~---:: .:.: : ·. ':· .. ;_ :\.~~· :·. · :•_-~ ::-::-_--_::. <·.: ·.'· . ,•-: .. ·.. · : .. :· '-· . ··,:·. . . ·, . ' . :· .... ·-..... Native backfill 1=1 {h:v) or flatter backcut to be properly benched ----(6) 1 cubic foot of ¾-inch crushed rock'. (7) Footing (1) Waterproofing membrane (optional): Liquid boot or approved mastic equivalent. (2) Drain= Miradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls; Miradrain 6200 or J-drain 200 or equivaJent for waterproofed walls (all perforations down). (3) Filt~r fabric: Mirafi 140N or approved equivalent. place fabric flap behind core. . . . (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down). · (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Gravel= Clean, crushed, ¾ to 1½ inch. (7) Footing: If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnicaJ consultant. RETAINING WALL DETAIL -ALTERNATIVE B . Detail 2 G ,·. ~ (1) Waterproofing membrane-~ CMU or reinforced-concrete wall Structural footing or settlement-sensitive improvement Provide surf ace drainage 2:1 (h:v) slope ., ---=t ,·. ~ ±12 Inches 7- (S) Weep hole H [ Proposed grade sloped to drain per precise civil drawing~ <0.~\\X\ '<-<(,::---:: Footing and wall tjesign by others Heel 1t------w1·dt.:-h ----i (3) Riter fabric (2) Gravel (4) Pipe (7) Footing (1) Waterproofing membrane: Liquid boot or approved masticequivalent. (2) Gravel: Clean, crushed, ¾ to 1½ inch. (3) Filter fabric: Mirafi 140N or approved equivalent. (8) Native backfill (6) Clean sand backfill 1:1 (h=v) or flatter backcut to be properly benched · (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down). · (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surf ace. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Clean sand backfill: Must have sand equivalent value (S.E.) of 35 or greater; can be densified by water jetting upon approval by geotechnical engineer. (7) Footing: If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional ''heel" drain will likely be required by geotechnical consultant. (8) Native backfill: If E.I. (21 and S.E. t35 then all sand requirements also may not be required and will be reviewed by the geotechnical consultant. i ,, (i,. !Ii ... RETAINING WALL DETAIL -ALTERNATIVE C Detail 3 and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall may be· constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an E.I. potential of greater than 50 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). If gravel backdrains for the below- grade/underground walls are proposed, the drains should outlet via gravity or a sump pump this is doubly redundant. In lieu of backdrains, the below-grade/underground walls should be designed to additionally withstand the increased hydrostatic pressure, and not leak or become discolored. Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than ± 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes, only, in walls higher than 2 feet, is not recommended. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.I. <50). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1 /360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be placed no greater than 20 feet on-center, in accordance with the structural engineer's/wall designer's recommendations, regardless of whether or not transition conditions exist. Expansion joints should be sealed with a flexible, non-shrink grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun CeoSoils, lne. W.O. 6087-A-SC June 16, 201 o Page 18 TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS Slope Creep Soils at the site may be expansive and therefore, may become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth of these shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 1 o feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences/walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication/swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, this information should be provided to any homeowner. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 1 O feet, some settlement and tilting of the walls/fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be constructed on deepened foundations without any consideration for creep forces, where the expansion index of the materials comprising the outer 15 feet of the slope is less than 50. The strength of the concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate corrosion, as warranted. DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS The soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page 19 that any homeowner be notified of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exteriorflatwork: 1 . The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. If very low expansive soils are present, only optimum moisture content, or greater, is required and specific presoaking is not warranted. The moisture content of the subgrade should be proof tested within 72 hours prior to pouring concrete. 2. Concrete slabs should be cast over a non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are present, the rock or gravel or sand may be deleted. The layer or subgrade should be wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. If subgrade soils within the top 7 feet from finish grade are very low expansive soils (i.e., E.I. ~20), then 6x6-W1 .4xW1 .4 welded-wire mesh may be substituted for the rebar, provided the reinforcement is placed on chairs, at slab mid-height. The exterior slabs should be scored or saw cut, ½ to % inches deep, often enough so that no section is greater than 1 O feet by 1 0 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. · W.O. 6087-A-SC June 16, 2010 Page 20 6. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. If very low expansion soils are present, footings need only be tied in one direction. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 1 O. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall ·to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including post-construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner. 12. Air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. A/C waste water lines should be drained to a suitable non-erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087agun GeoSoils, Ine. W.O. 6087-A-SC June 16, 201 O Page 21 post-construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and is anticipated to potentially affect improvements or structures (e.g., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughoutthe slope region, wet of the fill's optimum moisture content, as was done on this project. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the 1997 USC and/or adopted California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. Expansion joints in walls should be placed no greater than 20 feet on-center, and in accordance with the structural engineer's recommendations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to any homeowner. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to s_ustain p_lant life should be provided for planted slopes. Over-watering should be avoided as it adversely_affects site improvements, and causes perched groundwater conditions. Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Irrigation-of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC _June 16, 2010 Page 22 Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that future landscaping or construction activities do not create adverse drainage conditions. . Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground. In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of 1 percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of . planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area{s). Although not a geotechnical requirement, roof gutters, downspouts, or other appropriate means may be utilized to control roof drainage. Downspouts, or drainage devices, should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Erosion Control Graded slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum distance of 1 O feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the planter could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture retarder to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page 23 to the type of vegetation chosen and their potential effect upon surface improvements {i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or other non-erosive devices {e.g., paved swales or ditches; below grade, solid tight-lined PVC pipes; etc.), that will carry the water away from the house, to an appropriate outlet, in accordance with the recommendations of the design civil engineer. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design {as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Site Improvements If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. Pools and/or spas should not be constructed without specific design and construction recommendations from GSI, and this construction recommendation should be provided to the homeowner and/or other interested parties. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench and retaining wall backfills, flatwork, etc. Tile Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page 24 consider additional steel reinforcement for concrete slabs-on-grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs-on-grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street, driveway approaches, driveways, parking areas, and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to evaluate that the excavations have been made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching/Temporary Construction Backcuts Considering the nature of the onsite earth materials, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls/backcuts at the angle of repose (typically 25 to 45 degrees [except as specifically superceded within the text of this report]), should be anticipated. All excavations should be observed by an engineering geologist or soil engineer from GSI, prior to workers entering the excavation or trench, and minimally conform to CAL-OSHA, state, and local safety codes. Should adverse conditions exist, appropriate recommendations would be offered at that time. The above recommendations should be provided to any contractors and/or subcontractors, or homeowners, etc., that may perform such work. Utility Trench Backfill 1. All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of · A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 25 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to evaluate the desired results. 2. Exterior trenches adjacent to, and within areas extending below a 1 : 1 plane projected from the outside bottom-edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to evaluate the desired results. 3. All trench excavations should conform to CAL-OSHA, state, and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: • During grading/recertification. • During excavation. • During placement of subdrains, toe drains, or other subdrainage devices, prior to placing fill and/or backfill. • -After excavation of building footings, retaining wall footings, and free standing walls footings, prior to ~he placement of reinforcing steel or concrete. • Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor retarders (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbi_ng, utility line trenches, and retaining wall backfill. A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 o Page 26 • During slope construction/repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. • When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construction. 0 A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. • GSI should review project sales documents to homeowner for geotechnical aspects, including irrigation practices, the conditions outlined above, etc., prior to any sales. At that stage, GSI will provide homeowners maintenance guidelines which should be incorporated into such documents. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer/designer. Please note that the recommendations contained herein are not intended to preclude the transmission of water or vapor through the slab or foundation. The structural engineer/foundation and/or slab designer should provide recommendations to not allow water or vapor to enter into the structure so as to cause damage to another building component, or so as to limit the installation of the type of flooring materials typically used for the particular application. The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and deflections in the various slab, foundation, and other elements in order to develop appropriate, design-specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer/designer should consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer/designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely that some, more restrictive details will be required. If the structural engineer/designer has any questions or requires further assistance, they should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 27 potential distress, the foundation and/or improvement's designer should confirm to GSI and the governing agency, in writing, that the proposed foundations and/or improvements can tolerate the amount of differential settlement and/or expansion characteristics and other design criteria specified herein. PLAN REVIEW Anal project plans (foundation, retaining wall, landscaping, etc.), should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in characteristics between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty, either express or implied, is given. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. The conclusions and recommendations presented herein should be provided to all interested/affected parties. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 28 The opportunity to be of service is greatly appreciated. If you have any questions, please do not hesitate to call our office. Attachments: Distribution: A&E Construction Appendix A -References Appendix B -General Earthwork, Grading Guidelines, and Preliminary Criteria (3) Addressee APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun W.O. 6087-A-SC June 16, 201 o Page29 GeoSoils, lne. APPENDIX A ·REFERENCES .·. '' APPENDIX A REFERENCES ACI Committee 318, 2008, Building code requirements for structural concrete (ACI 318-08) and commentary, dated January. ACI Committee 360, 2006, Design of slabs-on-ground (ACI 360R-06). ACI Committee 302, 2004, Guide for concrete floor and slab construction, ACI 302.1 R-04, dated June. · ACI Committee on Responsibility in Concrete Construction, 1995, Guidelines for authorities and responsibilities in concrete design and construction in Concrete International, vol 17, No. 9, dated September. American Society for Testing and Materials, 1998, Standard practice for installation of water vapor retarder used in contact with earth or granular fill under concrete slabs, Designation: E 1643-98 (Reapproved 2005). __ , 1997, Standard specification for plastic water vapor retarders used in contact with soil or granular fill under concrete slabs, Designation: E 1745-97 (Reapproved 2004). CTL Thompson, 2005, Controlling moisture-related problems associated with basement slabs-on-grade in new residential construction. Californta· Building Standards Commission, 2007, California Building Code. GeoSoils, Inc., 2004a, Foundation plan review, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California, W.O. 3460-82-SC, dated October 7. __ , 2004b, Final compaction report of grading, Building pad area, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California, W.O. 3460-B1-SC, dated September 14. __ , 2004c, Geotechnical review of structural plans, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California, W.O. 3460-A2-SC, dated August 23. __ , 2004d, Final compaction report of grading, Parcels 1 and 3, 6575 Black Rail Road, Carlsbad, San Diego County, California, W.O. 3460-B-SC, dated March 9. __ , 2003, Grading plan review, 6575 Black Rail Road, Proposed subdivision, City of Carlsbad, San Diego County, California, W.O. 3460-A1 -SC, dated October 8. __ , 2002a, Soil corrosivity test results, 6575 Black Rail Road, City of Carlsbad, San Diego County, California, W.O. 3460-A1 -SC, dated December 20. GeoSoils, lne. , 2002b, Preliminary geotechnical evaluation, 6575 Black Rail Road, Proposed --subdivision, Carlsbad, San Diego County, California, W.O. 3460-A-SC, dated November 27. International Code Council, Inc., 2006, International building code and international residential code for one-and two-family dwellings. International Conference of Building Officials, 2001, California building code, California code of regulations title 24, part 2, volume 1 and 2. __ , 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. Kanare, Howard, 2005, Concrete floors and moisture, Portland Cement Association, Skokie, Illinois. State of California, 2010, Civil Code, Sections 895 et seq. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix A Page2 • I APPENDIX B -GENERAL EARTHWORK,_GRADING G_UIDELINES AND PRELIMINARY CRITERIA ' .. . . GENERAL EARTHWORK, GRADING GUIDELINES, AND PRELIMINARY CRITERIA General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including. preparation of areas to be filled, placement of fill, installation of subdrains, excavations, and appurtenant structures or flatwork. The recommendations contained in the geotechnical report are part of these earthwork and grading guidelines and would supercede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new or revised recommendations which could supercede these guidelines or the recommendations contained in the geotechnical report. Generalized details follow this text. The contractor is responsible for the satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications and latest adopted code. In the case of conflict, the most onerous provisions shall prevail. The project geotechnical engineer and engineering geologist (geotechnical consultant), and/or their representatives, should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnlcal Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for general conformance with the recommendations of the geotechnical report(s), the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that an evaluation may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All remedial removals, clean-outs, prepared ground to receive fill, key excavations, and subdrain installation should be observed and documented by the geotechnical consultant prior to placing any fill. It is the contractor's responsibility to notify the geotechnical consultant when such areas are ready for observation. Laboratory and Field Tests Maximum dry density tests to determine the degree of compaction should be performed in accordance with American Standard Testing Materials test method ASTM designation D-1557. Random or representative field compaction tests should be performed in GeoSoils, lne. accordance with test methods ASTM designation D-1556, 0-2937 or D-2922, and 0-3017, at intervals of approximately ±2 feet of fill height or approximately every 1,000 cubic yards placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. Contractor's Responslblllty All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by a geotechnical consultant, and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the geotechnical consultant, arid to place, spread, moisture condition, mix, and compact the fill in accordance with the recommendations of the geotechnical consultant. The contractor should also remove all non-earth material considered unsatisfactory by the geotechnical consultant. Notwithstanding the services provided by the geotechnical consultant, it is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in strict accordance with applicable grading guidelines, latest adopted codes or agency ordinances, geotechnical report(s), and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material, should be removed and disposed of off-site. These removals must be concluded prior to placing fill. In-place existing fill, soil, alluvium, colluvium, or rock materials, as evaluated by the geotechnical consultant as being unsuitable, should be removed prior to any fill placement. Depending upon the soil conditions, these materials may be reused as compacted fills. Any materials incorporated as part of the compacted fills should be approved by the geotechnical consultant. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page2 Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other structures not located prior to grading, are to be removed or treated in a manner recommended by the geotechnical consultant. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground, extending to such a depth that surface processing cannot adequately improve the condition, should be overexcavated down to firm ground and approved by the geotechnical consultant before compaction and filling operations continue. Overexcavated and processed soils, which have been properly mixed and moisture conditioned, should be re-compacted to the minimum relative compaction as specified in these guidelines. Existing ground, which is determined to be satisfactory for support of the fills, should be scarified (ripped) to a minimum depth of 6 to 8 inches, or as directed by the geotechnical consultant. After the scarified ground is brought to optimum moisture content, or greater and mixed, the materials should be compacted as specified herein. If the scarified zone is greater than 6 to 8 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 to 8 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report, or by the on-site geotechnical consultant. Scarification, disc harrowing, or other acceptable forms of mixing should continue until the soils are broken down and free of large lumps or clods, until ,he working surface is reasonably uniform and free from ruts, hollows, hummocks, mounds, or other uneven features, which would inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical [h:v]), the ground should be stepped or benched. The lowest bench, which will act as a key, should be a minim1.Jm of 15 feet wide and should be at least 2 feet deep into firm material, and approved by the geotechnical consultant. In fill-over-cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet, with the key founded on firm material, as designated by the geotechnical consultant. As a general rule, unless specifically recommended otherwise. by the geotechnical consultant, the minimum width of fill keys should be equal to ½ the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toes of fill benches, should be observed and approved by the geotechnical consultant prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained. A&E Construction Flle:e:\wp9\6000\6087a.gun GeoSoils, Jne. Appendix B Page3 COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been evaluated to be suitable by the geotechnical consultant. These materials should be free of roots, tree branches, other organic matter, or other deleterious materials. All unsuitable materials should be removed from the fill as directed by the geotechnical consultant. Soils of poor gradation, undesirable expansion potential, or substandard strength characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other approved material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill/bedrock contact. Oversized materials defined as rock, or other irreducible materials, with a maximum dimension greater than 12 inches, should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the geotechnical consultant. Oversized material should be taken offsite, or placed in accordance with recommendations of the geotechnical consultant in areas designated as suitable for rock disposal. GSI anticipates that soils to be utilized as fill material for the subject project may contain some rock. Appropriately, the need for rock disposal may be necessary during grading operations on the site. From a geotechnical standpoint, the depth of any rocks, rock fills, or rock blankets, should be a sufficient distance from finish grade. This depth is generally the same as any overexcavation due to cut-fill transitions in hard rock areas, and generally facilitates the excavation of structural footings and substructures. Should deeper excavations be proposed (i.e., deepened footings, utility trenching, swimming pools, spas, etc.), the developer may consider increasing the hold-down depth of any rocky fills to be placed, as appropriate. In addition, some agencies/jurisdictions mandate a specific hold-down depth for oversize materials placed in fills. The hold-down depth, and potential to encounter oversize rock, both within fills, and occurring in cut or natural areas, would need to be disclosed to all interested/affected parties. Once approved by the governing agency, the hold-down depth for oversized rock (i.e., greater than 12 inches) in fills on this project is provided as 10 feet, unless specified differently in the text of this report. The governing agency may require that these materials need to be deeper, crushed, or reduced to less than 12 inches in maximum dimension, at their discretion. To facilitate Mure trenching, rock (or oversized material), should not be placed within the hold-down depth feet from finish grade, the range offoundation excavations, future utilities, or underground construction unless specifically approved by the governing agency, the geotechnical consultant, and/or the developer's representative. If import material is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the geotechnical consultant to evaluate it's physical properties and suitability for use onsite. Such testing A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page4 should be performed three (3) days prior to importation. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the geotechnical consultant as soon as possible. Approved fill material should be placed in areas prepared to receive fill in near horizontal layers, that when compacted, should not exceed about 6 to 8 inches in thickness. The geotechnical consultant may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optiml.lm should be watered and mixed, and wet fill layers should be aerated by scarification, or should be blended with drier material. Moisture conditioning, blending, and mixing of the fill layer should continue until the fill materials have a uniform moisture content at, or above, optimum moisture. After each layer has been evenly spread, moisture conditioned, and mixed, it should be uniformly compacted to a minimum of 90 percent of the maximum density as evaluated by ASTM test designation D-1557, or as otherwise recommended by the geotechnical consultant. Compaction equipment should be adequately sized and should be specifically designed for soil compaction, or of proven reliability to efficiently achieve the specified degree of compaction. Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative compaction, or improper moisture is in evidence, the particular layer or portion shall be re-worked until the required density and/or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the geotechnical consultant. In general, per the 1997 UBC and/or latest adopted version of the California Building Code (CBC), fill slopes should be designed and constructed at a gradient of 2:1 (h:v), or flatter. Compaction pf slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. A final evaluation of fill slope compaction should be based on observation and/or testing of the finished slope face. Where compacted fill slopes are designed steeper than 2:1 (h:v), prior approval from the governing agency, specific material types, a higher minimum relative compaction, special reinforcement, and special grading procedures will be recommended. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix 8 Page 5 If an alternative to over-building and cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 1 O feet of each lift of fill by undertaking the following: 1. An extra piece of equipment consisting of a heavy, short-shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the slopes, and extend out over the slope to provide adequate compaction to the face of the slope. 2. Loose fill should not be spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re-rolling. 3. Field compaction tests will be made in the outer (horizontal) ±2 to ±8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to evaluate compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to evaluate compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix, and recompact the slope material as necessary to achieve compaction. Additional testing should be performed to evaluate compaction. SUBDRAIN INSTALLATION Subdrains should be installed in approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical consultant. The geotechnical consultant may recommend and direct changes in subdrain line, grade, arid drain material in the field, pending exposed conditions. The location of constructed subdrains, especially the outlets, should be recorded/surveyed by the project civil engineer. Drainage at the subdrain outlets should be provided by the project civil engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the geotechnical consultant. If directed by the geotechnical consultant, further excavations or overexcavation and refilling of cut areas should be performed, and/or remedial grading of A&E Construction Flle:e:\wp9\6000\6087a.gun GeoSoils, lne .. Appendix B Page6 cut slopes should be performed. When fill-over-cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the geotechnical consultant prior to placement of materials for construction of the fill portion of the slope. The geotechnical consultant should observe all cut slopes, and should be notified by the contractor when excavation of cut slopes commence. If, during the course of grading, unforeseen adverse or potentially adverse geologic conditions are encountered, the geotechnical consultant should investigate, evaluate, and make appropriate recommendations for mitigation of these conditions. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by the geotechnical consultant, whether anticipated or not. Unless otherwise specified in geotechnical and geological report(s), no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractor's responsibility. Erosion control and drainage devices should be designed by the project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental agencies, and/or in accordance with the recommendations of the geotechnical consultant. COMPLETION Observation, testing, and consultation by the geotechnical consultant should be conducted during the grading operations in order to state an opinion that all cut and fill areas are graded in accordance with the approved project specifications. After completion of grading, and after the geotechnical consultant has finished observations of the work, final reports should be submitted, and may be subject to review by the controlling governmental agencies. No further excavation or filling should be undertaken without prior notification of the geotechnical consultant or approved plans. All finished cut and fill slopes should be protected from erosion and/or be planted in accordance with the project specifications and/or as recommended by a landscape architect. Such protection and/or planning should be undertaken as soon as practical after completion of grading. PRELIMINARY OUTDOOR POOL/SPA DESIGN RECOMMENDATIONS The following preliminary recommendations are provided for consideration in pool/spa design and planning. Actual recommendations should be provided by a qualified geotechnical consultant, based ·on site specific geotechnical conditions, including a subsurface investigation, differential settlement potential, expansive and corrosive soil potential, proximity of the proposed pool/spa to any slopes with regard to slope creep and lateral fill extension, as well as slope setbacks per code, and geometry of the proposed A&E Construction Ffle:e:\wp9\6000\6087a.gun GeoSoils, Jne. Appendix B Page7 improvements. Recommendations for pools/spas and/or deck flatwork underlain by expansive soils, or for areas with differential settlement greater than ¼-inch over 40 feet horizontally, will be more onerous than the preliminary recommendations presented below. The 1 :1 (h:v) influence zone of any nearby retaining wall site structures should be delineated on the project civil drawings with the pool/spa. This 1 :1 (h:v) zone is defined as a plane up from the lower-most heel of the retaining structure, to the daylight grade of the nearby building pad or slope. If pools/spas or associated pool/spa improvements are constructed within this zone, they should be re-positioned (horizontally or vertically) so that they are supported by earth materials that are outside or below this 1 :1 plane. If this is not possible given the area of the building pad, the owner should consider eliminating these improvements or allow for increased potential for lateral/vertical deformations and associated distress that may render these improvements unusable in the future, unless they are periodically repaired and maintained. The conditions and recommendations presented herein should be disclosed to all homeowners and any interested/affected parties. General 1 . The equivalent fluid pressure to be used for the pool/spa design should be 60 pounds per cubic foot (pcf) for pool/spa walls with level backfill, and 75 pcf for a2:1 sloped backfill condition. In addition, backdrains should be provided behind pool/spa walls subjacent to slopes. 2. Passive earth pressure may be computed as an equivalent fluid having a density of 150 pcf, to a maximum lateral earth pressure of 1 ,000 pounds per square foot (psf). 3. An allowable coefficient of friction between soil and concrete of 0.30 may be used with the dead load forces. 4. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 5. Where pools/spas are planned near structures, appropriate surcharge loads need to be incorporated into design and construction by the pool/spa designer. This includes, but is not limited to landscape berms, decorative walls, footings, built-in barbeques, utility poles, etc. 6. All pool/spa walls should be designed as "free standing" and be capable of supporting the water in the pool/spa without soil support. The shape of pool/spa in cross section and plan view may affect the performance of the pool, from a geotechnical standpoint. Pools and spas should also be designed in accordance with Section 1806.5 of the 1997 UBC. Minimally, the bottoms of the pools/spas, should maintain a distance H/3, where His the height of the slope (in feet), from the slope face. This distance should not be less than 7 feet, nor need not be greater than 40 feet. A&E Construction Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page 8 7. The soil beneath the pool/spa bottom should be uniformly moist with the same stiffness throughout. If a-fill/cut transition occurs beneath the pool/spa bottom, the cut portion should be overexcavated to a minimum depth of 48 inches, and replaced with compacted fill, such that there is a uniform blanket that is a minimum of 48 inches below the pool/spa shell. If very low expansive soil is used for fill, the fill should be placed at a minimum of 95 percent relative compaction, at optimum moisture conditions. This requirement should be 90 percent relative compaction at over optimum moisture if the pool/spa is constructed within or near expansive soils. The potential for grading and/or re-grading of the pool/spa bottom, and attendant potential for shoring and/or slot excavation, needs to be considered during all aspects of pool/spa planning, design, and construction. 8. If the pool/spa is founded entirely in compacted fill placed during rough grading, the deepest portion of the pool/spa should correspond with the thickest fill on the lot. 9. Hydrostatic pressure relief valves should be incorporated into the pool and spa designs. A pool/spa under-drain system is also recommended, with an appropriate outlet for discharge. 10. All fittings and pipe joints, particularly fittings in the side of the pool or spa, should be properly sealed to prevent water from leaking into the adjacent soils materials, and be fitted with slip or expandible joints between connections transecting varying soil conditions. 11 . An elastic expansion joint (flexible waterproof sealant) should be installed to prevent water from seeping into the soil at all deck joints. 12. A reinforced grade beam should be placed around skimmer inlets to provide support and mitigate cracking around the skimmer face. 13. In order to reduce unsightly cracking, deck slabs should minimally be 4 inches thick, and reinforced with No. 3 reinforcing bars at 18 inches on-center. All slab reinforcement should be supported to ensure proper mid-slab positioning during the placement of concrete. Wire mesh reinforcing is specifically not recommended. Deck slabs should not be tied to the pool/spa structure. Pre-moistening and/or pre-soaking of the slab subgrade is recommended, to a depth of 12 inches (optimum moisture content), or 18 inches (120 percent of the soil's optimum moisture content, or 3 percent over optimum moisture content, whichever is greater), for very low to low, and medium expansive soils, respectively. This moisture content should be maintained in the subgrade soils during concrete placement to promote uniform curing of the concrete and minimize the development of unsightly shrinkage cracks. Slab underlayment should consist of a 1-to 2-inch leveling course of sand (S.E. >30) and a minimum of 4 to 6 inches of Class 2 base compacted to 90 percent. Deck slabs within the H/3 zone, where H is the height of the slope (in feet), will have an increased potential for distress relative to other areas outside of the H/3 zone. If distress is undesirable, A&E Construction Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page9 improvements, deck slabs or flatwork should not be constructed closer than H/3 or 7 feet (whichever is greater) from the slope face, in order to ·reduce, but not eliminate, this potential. · 14. Pool/spa bottom or deck slabs should be founded entirely on competent bedrock, or properly compacted fill. Fill should be compacted to achieve a minimum 90 percent relative compaction, as discussed above. Prior to pouring concrete, subgrade soils below the pool/spa decking should be throughly watered to achieve a moisture content that is at least 2 percent above optimum moisture content, to a depth of at least 18 inches below the bottom of slabs. This moisture content should be maintained in the subgrade soils during concrete placement to promote uniform curing of the concrete and minimize the development of unsightly shrinkage cracks. 15. In order to reduce unsightly cracking, the outer edges of pool/spa decking to be bordered by landscaping, and the edges immediately adjacent to the pool/spa, should be underlain by an 8-inch wide concrete cutoff shoulder (thickened edge) extending to a depth of at least 12 inches below the bottoms of the slabs to mitigate excessive infiltration of water under the pool/spa deck. These thickened edges should be reinforced with two No. 4 bars, one at the top and one at the bottom. Deck slabs may be minimally reinforced with No. 3 reinforcing bars placed at 18 inches on-center, in both directions. All slab reinforcement should be supported on chairs to ensure proper mid-slab positioning during the placement of concrete. 16. Surface and shrinkage cracking of the finish slab may be reduced if a low slump and water-cement ratio are maintained during concrete placement. Concrete utilized should have a minimum compressive strength of 4,000 psi. Excessive water added to concrete prior to placement is likely to cause shrinkage cracking, and should be avoided. Some concrete shrinkage cracking, however, is unavoidable. 17. Joint and sawcut locations for the pool/spa deck should be determined by the design engineer and/or contractor. However, spacings should not exceed 6 feet on center. 18. Considering the nature of the onsite earth materials, it ·should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls/backcuts at the angle of repose (typically 25 to 45 degrees), should be anticipated. All excavations should be observed by a representative of the geotechnical consultant, including the project geologist and/or geotechnical engineer, prior to workers entering the excavation or trench, and minimally conform to Cal/OSHA ("Type C" soils may be assumed), state, and local safety codes. Should adverse conditions exist, appropriate recommendations should be offered at that time by the geotechnical consultant. GSI does not consult in the area of safety engineering and the safety of the construction crew is the responsibility of the pool/spa builder. A&E Construction Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page 10 19. It is imperative that adequate provisions for surface drainage are incorporated by the homeowners into their overall improvement scheme. Ponding water, ground saturation and flow over slope faces, are all situations which must be avoided to enhance long term performance of the pool/spa and associated improvements, and reduce the likelihood of distress. 20. Regardless of the methods employed, once the pool/spa is filled with water, should it be emptied, there exists some potential that if emptied, significant distress may occur. Accordingly, once filled, the pool/spa should not be emptied unless evaluated by the geotechnical consultant and the pool/spa builder. · 21 . For pools/spas built within (all or part) of the 1997 Uniform Building Code (UBC) setback and/or geotechnical setback, as indicated in the site geotechnical documents, special foundations are recommended to mitigate the affects of creep, lateral fill extension, expansive soils and settlement on the proposed pool/spa. Most municipalities or County reviewers do not consider these effects in pool/spa plan approvals. As such, where pools/spas are proposed on 20 feet or more of fill, medium or highly expansive soils, or rock fill with limited "cap soils" and built within 1997 UBC setbacks, or within the influence of the creep zone, or lateral fill extension, the following should be considered during design and construction: OPTION A: Shallow foundations with or without overexcavation of the pool/spa "shell," such that the pool/spa is surrounded by 5 feet of very low to low expansive soils (without irreducible particles greater that 6 inches), and the pool/spa walls closer to the slope(s) are designed to be free standing. GSI recommends a pool/spa under-drain or blanket system (see attached Typical Pool/Spa Detail). The pool/spa builders and owner in this optional construction technique ·should be generally satisfied with pool/spa performance under this scenario; however, some settlement, tilting, cracking, and leakage of the pool/spa is likely over the life of the project. OPTION B: Pier supported pool/spa foundations with or without overexcavation of the pool/spa shell such thatthe pool/spa is surrounded by 5 feet of very low to low expansive soils (without irreducible particles greater than 6 inches), and the pool/spa walls closer to the slope(s) are designed to be free standing. The need for a pool/spa under-drain system may be installed for leak detection purposes. Piers that support the pool/spa should be a minimum of 12 inches in diameter and at a spacing to provide vertical and lateral support of the pool/spa, in accordance with the. pool/spa designers recommendations, local code, and the 1997 UBC. The pool/spa builder and owner in this second scenario construction technique should be more satisfied with pool/spa performance. This construction. will reduce settlement and creep effects on the pool/spa; however, it will not eliminate these potentials, nor make the pool/spa "leak-free." A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix 8 Page 11 22. The temperature of the water lines for spas and pools may affect the corrosion properties of site soils, thus, a corrosion specialist should be retained to review all spa and pool plans, and provide mitigative recommendations, as warranted. Concrete mix design should be reviewed by a qualified corrosion consultant and materials engineer. 23. All pool/spa utility trenches should be compacted to 90 percent of the laboratory standard, under the full-time observation and testing of a qualified geotechnical consultant. Utility trench bottoms should be sloped away from the primary structure on the property (typically the residence). 24. Pool and spa utility lines should not cross the primary structure's utility lines (i.e., not stacked, or sharing of trenches, etc.). 25. The pool/spa or associated utilities should not intercept, interrupt, or otherwise adversely impact any area drain, roof drain, or other drainage conveyances. If it is necessary to modify, move, or disrupt existing area drains, subdrains, or tightlines, then the design civil engineer should be consulted, and mitigative measures provided. Such measures should be further reviewed and approved by the geotechnical consultant, prior to proceeding with any further construction. · 26. The geotechnical consultant should review and approve all aspects of pool/spa and flatwork design prior to construction. A design civil engineer should review all aspects of such design, including drainage and setback conditions. Prior to acceptance of the pool/spa construction, the project builder, geotechnical consultant and civil designer should evaluate the performance of the area drains and other site drainage pipes, following pool/spa construction. · 27. All aspects of construction should be reviewed and approved by the geotechnical consultant, including during excavation, prior to the placement of any additional fill, prior to the placement of any reinforcement or pouring of any concrete. 28. Any changes in ~esign or location of the pool/spa should be reviewed and approved by the geotechnical and design civil engineer prior to construction. Field adjustments should not be allowed until written approval of the proposed field changes are obtained from the geotechnical and design civil engineer. 29. Disclosure should be made to homeowners and builders, contractors, and any interested/affected parties, that pools/spas built within about 15 feet of the top of a slope, and/or H/3, where H is the height of the slope (in feet), will experience some movement or tilting. While the pool/spa shell or coping may not necessarily crack, the levelness of the pool/spa will likely tilt toward the slope, and may not be esthetically pleasing. The same is true with decking, flatwork and other improvements in this zone. A&E Construction Ffle:e:\wp9\6000\6087agun GeoSoils, lne. Appendix B Page 12 30. Failure to adhere to the above recommendations will significantly increase the potential for distress to the pool/spa, flatwork, etc. 31. Local seismicity and/or the design earthquake will cause some distress to the pool/spa and decking or flatwork, possibly including total functional and economic loss. 32. The information and recommendations discussed above should be provided to any contractors and/or subcontractors, or homeowners, interested/affected parties, etc., that may perform or may be affected by such work. JOB SAFETY General At GSI, getting the job done safely is of primary concern. The following is the company's safety considerations for use by all employees on multi-employer construction sites. On-ground personnel are at highest risk of injury, and possible fatality, on grading and construction projects. GSI recognizes that construction activities·wm vary on each site, and that site safety is the prime responsibility of the contractor; however, everyone must be safety conscious and responsible at all times. To achieve our goal of avoiding accidents, cooperation between the client, the contractor, and GSI personnel must be maintc;lined. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety of field personnel on grading and construction projects: Safety Meetings: GSI field personnel are directed to attend contractor's regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for, and are to be worn by GSI personnel, at all times, when they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing amber beacons, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. A&E Construction Flle:e:\wp9\6000\6087a.gun GeoSoils, Ine. AppendixB Page 13 Test Pits Location, Orientation. and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technician's safety. Efforts will be made to coordinate locations with the grading contractor's authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of currenttraffic. The contractor's authorized representative (supervisor, grade checker, dump man, operator, etc.) should direct excavation of the pit and safety during the test period. Of paramount concern should be the soil technician's safety, and obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed away from oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. This zone is established for safety and to avoid excessive ground vibration, which typically decreases test results. When taking slope tests, the technician should park the vehicle directly above or below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractors representative should effectively keep all equipment at a safe operational distance (e.g., 50 feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads, cut and fill areas or other factors that may affect site access and site safety. In the event that the technician's safety is jeopardized or compromised as a result of the contractor's failure to comply with any of the above, the technician is required, by company policy, to immediately withdraw and notify his/her supervisor. The grading contractor's representative will be contacted in an effort to affect a solution. However, in the interim, no further testing will be performed until the situation is rectified. Any fill placed can be considered unacceptable and subject to reprocessing, recompaction, or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we requestthatthe contractor bring this to the technician's attention and notify this office. Effective communication and coordination between the contractor's representative and the soil technician is strongly encouraged in order to implement the above safety plan. A&E Construction File:e:\wp9\6000\6087a.gun CeoSoHs, lne. AppendixB Page 14 Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid. back; 2) displays any evidence of instability, has any loose rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance with Cal/OSHA and/or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down" on the equipment. If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his/her supervisor. The contractor's representative will be contacted in an effort to affect a solution. All backfill not tested due to" safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the C(?ntractor and owner/developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify Cal/OSHA and/or the proper controlling authorities. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page 15 ~-Toe of slope as shown on grading plan ~-.-~:-.4_._· .. :·.-.:·.· .. --·: .. ··-:. · .. -...... : .. -.- Original ground surface to be \ { < .. _·· _.. : .. · .. ·.: .. ~ ·.,/·:·,: ····-~---·· -._-__ ·. restored with compacted fill \ / ._<_:··----·.'..> ·:.:<. _:·~~-~.~~~t~d-~!1 · :. :.=·_~--:-· : 2D ' .., I.;· -0··_,,:. :: :·.-:-~. :_ ,,_ .: .. :~ :. __ :;_·_:·_ -~~~-. ~ ,_::._: ._.:·:: ·._'-.' :·. ;_ :,: .. :·-·-~---------- Back-cut varies. For deep removals, backcut should be made no steeper than 1=1 (H:V), or flatter as necessary for safety considerations. / ~/0<:-/ I \.__Original ground surface of ~ <f / D • Anticipated removal of unsuitable material ~_,/ (depth per geotechnlcal engileer) ~~ "'' / Provide a 1:1 (H:V) minimum projection from toe of slope as shown on grading plan to the recommended removal depth. Slope height, site conditions, and/ or local conditions could dictate flatter projections. ...... oGfl ·.: c • FILL SLOPE TOEING OUT ON FLAT ALLUVIATED CANYON DETAIL Plate B-3 l•/1¥1~ ~, .":-. t ... , C •• f J_ • • Pr oposed grade ~ ---- Proposed additional compacted fill r--Previously placed, temporary compacted fill for drainage only --- ,, {<••••••••••·••••••••••••••••••: •••••••••••••• ••••••·•••• :t•••••·•uu ⇒ 0.?c:•::: ·•· \ .. ~ '\:/::::::::::::::::::::::::::::::::::::::::::::::::;:::-~:::"'Unsuitaple -~ter:ial {te be· removed) 1-9'~·:z::::::::::::::::::::::::\;):?.: ... · ·:-: .·. · .. ~-.. : ·.: ....... : ;_ .. :-,, ... ·.. . .. . Existing compacted fill ~~-··-:-::::::::::::::::::::•;~ · ,:: ... ,··: ··.-·. :. : . 7-~,<-:::<ay\\".~ o,.. ,.. . . . . . . •.. . . . . . . ½ '\ \ \ \ \ ., Y.--:.::·:·· · ... ✓-~ /\\ ,,;.Y A. ./ :Y""' \" /. \..__ Bedrock or approved native material ..::;.___ To be removed before placing __ ...,. additional compacted fill REMOVAL ADJACENT TO EXISTING FILL ADJOINING CANYON FILL DETAIL Plate B-4 Toe of slope as shown on grading plan Proposed grade \ / / .,,.,.- / Natural slope to be restored with compacted fill / Compacted fill / / / Backcut varies -----r Subdrain by geotechnical consultant NOTES: 1. Where the natural slope approaches or exceeds the design slope ratio, special recommendations would be provided by the geotechnical consultant. · 2. The need for and disposition of drains should be evaluated by the geotechnical consultant, based upon exposed conditions. ~ •. , . ',: c. , FILL OVER NATURAL (SIDEHILL FILL) DETAIL Plate 8-7 Proposed finish grade --Natural grade . ---✓---'~- H • height of slope i --:-. ·:-~·.: :· .. ·· .. .. . . . ··;. ······ ... · .. ·:, .· . . '• . . . ~ Typical benching (4-foot minimum) Subdrain as recommended by geotechnical consultant NOTES= 1. 15-foot minimum to be maintained from proposed finish slope face to backcut. 3-foot minlrrllln 2. The need and disposition of drains will be evaluated by the geotechnical consultant based on field conditions. 3. Pad overexcavation and recompaction should be performed if evaluated to be necessary by the geotechnical consultant. ~·•= : c. -~-SKIN FILL OF NATURAL GROUND DETAIL Plate 8-10 Natural grade Proposed pad.grade . . ... ': ...... · .. , . ··. · -: . ile : · . .-'.·:·.··<.·::_:.:·:.· .. /·'._: :··-0· · ., .. ,: .. ··. . . .·. . . . . . .. f\el!f fC\a.tena\ .... · . . . :. . .. _,.,.:.--- ._, _ ;--_~ ;: .. :~··· . .-... ;:. ·:::=-~ : .. > :.· .. ~~.\.~_ ... :~ . J_ ·· . . -~--.. ~~~-- CUT LOT OR MATERIAL -TYPE TRANSITION Typical benching ( 4-foot minimum) Natural grade ... : . , .. .... :\:_,.:~ ...... ,.. J_ . -•~.:--. -~-.... :-_.:., .. ._;;J·. ·_·. --- . . . . : ~. ~ Bedrock or approved native material * Deeper overexcavation may be recommended by the geotechnlcal consultant in steep cut-fiU transition areas, such that the underlying topography is no steeper than 3:1 (H:V) CUT-FILL LOT (DAYLIGHT TRANSmON) TRANSITION LOT DETAILS Plate 8-12 MAP VIEW NOT TO SCALE Concrete cut-off wall SEE NO,._S __________ j B I Top of slope ~ 2-inch-thick sand layer Gravity-flow, nonperforated subdraln I=== pipe (tranm,ree) Toe of slope A I 7 I l5feel Pool 4-lnch perforated subdrain pipe (longitudinal) Coping ············································ ............................................ A' 4-inch perforated subdrain pipe (transverse) Pool Direction of drainage B' CROSS SECTION VIEW Coping NOTTO SCALE SEE NOTES Pool encapsulated in 5-foot thickness of sand --- 6-inch-thick gravel layer 8 r H NOTES Outlet per design cMI engineer Gravity-flow nonperforated subdrain pipe 4-inch perforated subdrain pipe I I . 1 1-sreet Coping · Vapor retarder Perforated subdrain pipe 1. 6-inch-thlck, clean gravel (¾ to 1½ inch) sub-base encapsulated in Mirafi 140N or equivalent, underlain by a 15-mff vapor retarder, with 4-inch-dlameter perforated pipe longitudinal connected to 4-inch-diameter perforated pipe transverse. Connect transverse pipe to 4-inch-diameter nonperforated pipe at low point and outlet or to sump pump area 2. Pools on fills thicker than 20 feet should be constructed on deep foundations; otherwise, distress (tilting, cracking, ('tc.) should be expected. · 3. Design does not apply to infinity-edge pools/spas. TYPICAL POOL/SPA DETAIL Plate B-17 SIDE VIEW Spoil pile TOP VIEW Flag Light Vehicle ----------50 feet-----------50 feet--------. ---------------:iooteer-------------- TEST PIT SAFETY DIAGRAM Plate B-20 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 619 258-7901 FAX 619 258-7902 A & E Construction Services P.O. Box 130400 Carl sbad. California 92013 Subject: Project: Transfer of Geotechnical Responsibility Geotechnical Engineer of Record Two Proposed Single-Family Residences 6575 Black Raj) Road City of Carlsbad, California July 11 ,201 I References: l ."Geotechnical Update, Parcel 1 of Parcel Map 19411 , APN 215-070-39, Carlsbad, San Diego County, Califomja," W.O. 6087-A-SC, Prepared by Geosoils lnc. Dated June 16, 2010. 2.''Preliminary Geotechnical Investigation, 6575 Black Rail Road, Proposed Subdivision, Carlsbad, San Diego County, California", W.O. 3460-A-SC, Prepared by GeoSoils Inc., Dated November 27, 2002. Ladies & Gentlemen: In accordance with your request, East County Soil Consultation and Engineering, Inc. is pleased to assume the responsibility of Geotechnical Engineer of Record for the referenced project. We have reviewed the referenced geotechnical reports and agree with the data, recommendations and conclusions. If we can be of further assistance, please do not hesitate to contact our office. EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 Mr. David Raum 261 Apple Blossum Lane Vista, California 92084 Subject: Soils Report Update 619 258-7901 FAX 619 258-7902 Proposed Single-Family Residence 1587 Triton Street Carlsbad, California 92009 References: See Attached Ladies & Gyntlemen: October 19, 2018 ProjectNo.11-1 127C5 In accordance with your request, we have reviewed the referenced soils reports and visited the subject site on October 16, 20 I 6. Site conditions were found as described in the referenced soils report (Reference No. I). Therefore, the recommendations provided in the referenced geotechnical report (Reference No. 3) are still valid for the proposed development. Following clearing and grubbing, i.e. the removal of vegetation, we recommend that existing fi ll soils be scarified to a minimum depth of 6 inches, moisture-conditioned within 2 percent over optimum and recompacted to a minimum of 90 percent relative compaction. 2016 CBC Seismic Design Criteria The proposed single-family residence should be designed in accordance with seismic design requirements of the 2016 California Building Code or the Structural Engineers Association of California using the following seismic design parameters: PARAMETER VALUE 2016 CBC and ASCE 7 REFERENCES Site Class D Table 20.3-1 I ASCE 7, Chapter 20 Maooed Spectral Acceleration For Short Periods, S, 1.093g Figure 16 13.3.1(1) Mapped Spectral Acceleration For a I -Second Period, 0.421 g Figure 16 I 3.3.1 (2) s, Site Coefficient, F. 1.063 Table 1613.3.3(1) Site Coefficient, F. 1.579 Table 1613.3.3(2) Adjusted Max. Considered Earthquake Spectral 1.162g Equation 16-37 Response Acceleration for Short Periods, SMs Adjusted Max. Considered Earthquake Spectral 0.665g Equation 16-38 Resoonse Acceleration for I-Second Period, SM, 5 Percent Damped Design Spectral Response 0.774g Equation 16-39 Acceleration for Short Periods, Sos 5 Percent Damped Design Spectral Response 0.443g Equation 16-40 Acceleration for I-Second Period, So, David Raum/ 1587 Triton Street/ Carlsbad Project No. 11-1 I 27C5 If we can be of further assistance, please do not hesitate to contact our office. Respectfully submitted, Mamadou Sah u Diallo, P.E. RCE 54071, GE 2704 MSD/md 2 David Raum/ 1587 Triton Street/ Carlsbad Project No. I /-I /27C5 REFERENCES I. ·'Report of Field Density Tests, Proposed Single-Farnily Residence, 6575 Black Rail Road (Lot No. 2), Carlsbad, California 92009", Prepared by East County Soil Consultation and Engi neering, Inc., Dated August 23, 2011 . 2. "Transfer of Geotechnical Responsibility, Geotechnical Engineer of Record, Two Proposed Single-Family Residences, 6575 Black Rail Road, City of Carlsbad, California", Prepared by East County Soil Consultation and Engineering, Inc., Dated July 11 , 2011. 3. "Geotechnical Update, Parcel I of Parcel Map 19411, APN 2 15-070-39, Carlsbad, San Diego County, California," W.O. 6087-A-SC, Prepared by Geosoils lnc. Dated June 16, 20 I 0. 4. "Final Compaction Report of Grading, Building Pad Area, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California." W.O. 34601-B-SC, Prepared by Geosoils Inc. Dated September 14, 2004. 5. "Preliminary Geotechnical Investigation, 6575 Black Rail Road, Proposed Subdivision, Carlsbad, San Diego County, California", W.O. 3460-A-SC, Prepared by GeoSoils Inc., Dated November 27, 2002. 3 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 (619) 258-7901 Fax 258-7902 A & E Construction Services P.O. Box 130400 Carlsbad, California 92013 Project: Report of Field Density Tests Proposed Single-Family Residence 6575 Black Rail Road (Lot No. 2) Carlsbad, California 92009 References: See Attached Ladies & Gentlemen: August 23, 2011 Project No.11-1127C5 This is to present the results of field density tests performed on the building pad for the the proposed single-family residence, including the backfill of the keystone retaining wall for the driveway at the subject site. In accordance with your request, in-place field density tests were performed in accordance with ASTM D1556 (Sand Cone Method). Backfill and grading were conducted between July 14 and August 19, 2011 under the observation and testing of a representi6ve of East County Soil Consultation & Engineering Inc. The results of the field density tests are presented on Page T-1 under "Table of Test Results". The laboratory determinations of the maximum dry densities and optimum moisture contents of the fill soils are set forth on Page L-1 under "Laboratory Test Results". The approximate test locations are shown on Plate No. l. Following clearing and grubbing, i.e. the removal of vegetation and deleterious materials, subgrade soils were overexcavated to a depth of approximately 2 feet below existing grade into dense terrace deposits. The bottom of the excavation was scarified to a depth of approximately 6 inches, moisture conditioned and compacted. On-site fill soils consisting of silty sand were placed in thin lifts, moisture conditioned around optimum and compacted in excess of 90 percent relative compaction. Compaction was achieved with the use of a Caterpillar 941 track loader and a hand whacker. A & E CONSTRUCTION SERVICES/ BLACK RAIL ROAD/ PROJECT NO. I l-l /27C5 Based on our field observations and density test results, it is our opinion that the grading operation for the the proposed single-family residence was performed in accordance with the referenced geotechnical reports (References No. 2 and No. 4) and local grading ordinances. If we can be of further assistance, please do not hesitate to contact our office. Pages T-1 , L-1 and Plate No. I are parts of this report. Respectfully Submitted, Mamadou Saliou Diallo, P.E. RCE 54071 , GE 2704 MSD/md 2 TEST SOIL NO. TYPE I 2 1 3 2 4 3 5 3 6 2 7 2 8 2 9 10 I 1 2 12 13 14 15 16 A & E CONSTRUCTION SERVICES/ BLACK RAIL ROAD/ PROJECT NO.11-1127C5 DEPTH OFFILL IN FEET 1 3 3 5 6 7 FG 2 2 4 5 7 2 8 FG 3 FG PAGE T-1 TABLE OF TEST RESULTS ASTMD1556 MAXIMUM FIELD DRY DRY MOISTURE DENSITY DENSITY %DRY WT. P.C.F. P.C.F 11.6 118.0 127.0 12.1 117.8 127.0 10.5 122.5 125.5 8.7 120.4 128.0 8.9 120.7 128.0 9.7 120.2 125.5 13.4 119.5 125.5 11.5 116.9 125.5 9.9 116.2 127.0 11. 7 121 .6 127.0 12.9 114.4 125.5 11.5 119.6 127.0 11.4 121.7 127.0 12.1 115.7 127.0 11.3 120.3 127.0 10.6 11 9.5 127.0 FG = FINISH GRADE 3 PERCENT COMPACTION 93 93 98 94 94 96 95 93 92 96 91 94 96 91 95 94 REMARKS A & E CONSTRUCTION SERVICES/ BLACK RAIL ROAD/ PROJECT NO. I J-1 l27C5 PAGE L-1 LABORATORY TEST RESULTS RESULTS OF MAXIMUM DENSITY AND OPTIMUM MOISTURE The maximum dry densities and optimum moisture contents of the fill materials as determined by ASTM D 1557, Procedures A and B which use 25 blows of a I 0-pound slide hammer falling from a height of 18 inches on each of 5 equal layers in a 4-inch diameter 1/30 cubic foot compaction cylinder and Procedure C which uses 56 blows of a 10-pound slide hammer falling from a height of 18 inches on each of 5 equal layers in a 6-inch diameter 1/13.3 cubic foot compaction cylinder are presented as follows: OPTlMUM MAXIMUM MOISTURE SOIL TYPE/ DRY DENSITY CONTENT PROCEDURE DESCRIPTION LB/CU. FT. %DRY WT. 1/A REDDISH BROWN SILTY SAND 127.0 10.0 2/A TAN BROWN SIL TY SAND 125.5 I 1.0 3/A DARK BROWN SIL TY SAND 128.0 9.5 4 ~ Tl<ITOtV -· --..,. •1 '\ I I \ I .1; \ I .~ ,1 I 1 I I ·" i, >t • '° •\b • 6( . '· • \'1,-,, •\\ EAST COUNTY SOIL CONSULTATION & ENGINEERING, INC. I 0925 HAR11-EY RD .• SUITE I, SANTEE. CA 92071 (619) 258-790 I Fait (619) 2511· 7902 S7X' &'"r- ~ A,O .Sc~ ~ • \'1 ~~-/I-/Jz7c5 PM-le /VO -I A & E CONSTRUCT/ON SERVICES/ BLACK RAIL ROAD! PROJECT NO. I I-I l27C5 REFERENCES 1. "Transfer of Geotechnical Responsibility, Geotechnical Engineer of Record, Two Proposed Single-Family Residences, 6575 Black Rail Road, City of Carlsbad, California", Prepared by East County Soil Consultation and Engineering, Inc., Dated July 11,2011. 2. "Geotechnical Update, Parcel 1 of Parcel Map 19411, APN 215-070-39, Carlsbad, San Diego County, California," W.O. 6087-A-SC, Prepared by Geosoils Inc. Dated June 16, 2010. 3. "Final Compaction Report of Grading, Building Pad Area, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California," W.0. 34601-B-SC, Prepared by Geosoils Inc. Dated September 14, 2004. 4. "Preliminary Geotechnical Investigation, 6575 Black Rail Road, Proposed Subdivision, Carlsbad, San Diego County, California", W.0. 3460-A-SC, Prepared by GeoSoils Inc., Dated November 27 , 2002. 5