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HomeMy WebLinkAboutCDP 2018-0038; ALLANSON-SELVIDGE CARLSBAD RESIDENCE; LIMITED GEOTECHNICAL REVIEW OF SHORING PLANS; 2019-03-18-... - .. - .. -.. .. .. .. ... • .. .. March 18, 2019 Paula Selvidge 2604 T rona Way Carlsbad, California 92009 CHRJSTIAN WHEELER ENGINEERING '\Nn nr:::vE1 OPMENT L . •-: , ,:J Subject: Limited Geotechnical Review of Shoring Plans Proposed Selvidge Residence, 5170 Carlsbad Boulevard, Carlsbad, California CWE 2180441.08 References: 1) Shoring Design Group, Response to City of Carlsbad Plan Check Correction, Selvidge Residence, dated March 17, 2020 2) Shoring Design Group, Temporary Shoring Design Submittal, Selvidge Residence, dated March 1 7, 2020 3) Shoring Design Group, Grading Plans, Shoring, Sheets 5 through 8, Allison-Selvidge Residence, dated March 17, 2020 4) Christian Wheeler Engineering, Report CWE 2180441.02, dated September 21, 2018 Dear Mrs. Selvidge: At your request, we have performed a limited geotechnical review of the referenced documents and shoring plans for the subject project in order to ascertain that the recommendations presented in the referenced geotechnical report have been implemented, and that no additional recommendations are needed due to changes in the proposed construction. Based on this review, it is our opinion that, in general, the plans reflect the recommendations contained in the referenced report, and that no additional recommendations are necessary. If you have any questions after reviewing this report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, ~NEERING Daniel B. A !er, RCE # 36037 ec: hfgeek@gmail.com; luis@sdarchitects.net; banlohno@plsaengineering.com, rreed@shoringdesigngroup.com 3980 Home Avenue" San Diego, CA 92105, 619-550-1700, FAX 619-550-1701 -.. ... 1111"1 .. -... .. ... -... ... .. .. ... -.. ... .... .. .. -... .. ... ... .. .. -... ... .... w CHRJSTIAN WHEELER. ENGINEERING February 14, 2020 Paula Selvidge CWE 2180441.07 2604 Trana Way Carlsbad, California 92009 Subject: References: Response to Third-Party Geotechnical Review, Log No. 20648 Proposed Selvidge Residence, 5170 Carlsbad Boulevard, Carlsbad, California 1) Pasco Laret Suiter and Associates, Grading Plans for Selvidge Residence, undated 2) Christian Wheeler Engineering, Report CWE 2150401.05, dated September 9, 2019 3) Hetherington Engineering, Inc., Third-Party Geotechnical Review, Proposed Single Family Residence, 5170 Carlsbad Boulevard, Carlsbad, California, dated September 9, 2019 (Log No. 20648) 4) HTK Structural Engineers, LLP, Foundation Plans, Allanson-Selvidge Residence, Sheets S01, Sl, S2, SD1.0, and SD1.1, dated August 7, 2019 5) Christian Wheeler Engineering, Report CWE 2150401.05, dated September 9, 2019 6) Christian Wheeler Engineering, Report CWE 2150401.03, dated December 5, 2018 7) Christian Wheeler Engineering, Report CWE 2150401.04, dated August 7, 2019 8) Christian Wheeler Engineering, Report CWE 2150401.02, dated September 21, 2018 Dear Mrs. Selvidge: In accordance with your request, we have prepared this report to present additional information required by the Carlsbad regarding the geotechnical issues at the site. The comments in the review letter and our responses to the comments in the referenced memorandum within our purview are presented below . City Comment 1: The Consultant should review the project grading and foundation plans, provide any additional geotechnical analyses/recommendations considered necessary, and confirm that the plans have been prepared in accordance with the geotechnical recommendations . CWE Response: See referenced report CWE 2180441.05 City Comment 2: The Consultant should provide a geotechnical map utilizing the current grading plan for the project to clearly show (at a minimum) a) existing site topography, b) existing 3 9 8 0 H o m e A v e n u e ♦ S a n D i e g o , C ,\ 9 2 1 0 5 ♦ 6 1 9 -5 5 0 -1 7 0 0 ♦ F ,\ X 6 1 9 -5 5 0 -1 7 0 1 ... ... ... ... ,.. ... .. ... ... .. .. ... ... ... .. .. ... ... -... -... .. --... -... -... ... ... .. ... -... CWE 2180441.07 February 14, 2020 Page No. 2 structures/improvements, c) proposed structures/improvements, d) proposed finish grades, e) geologic conditions, f) locations of the subsurface explorations, etc. CWE Response: See attached Plate No. 1. City Comment 3: The Consultant should provide a geologic cross-section(s) utilizing the current grading plan for the project to clearly show (at a minimum) a) existing site topography, b) existing structures/improvements, c) proposed structures/improvements, d) proposed finish grades, e) geologic conditions, f) locations of the subsurface explorations, etc. CWE Response: See attached Plate Nos. 2 and 3 . City Comment 4: The Consultant should confirm during grading/ construction that the near surface soils possess a very low potential as assumed . CWE Response: To be determined during grading . City Comment 5: The Consultant should address impacts to adjacent property and improvements as a result of proposed site grading and construction . CWE Response: Provided the recommendations presented in our referenced geotechnical report are incorporated into the proposed project's design and construction and that sound construction practices are followed, the proposed site development as recommended should not measurably destabilize neighboring properties or induce the settlement of adjacent structures . City Comment 6: The Consultant should provide the seismic design category. CWE Response: The seismic design category for the site is D . City Comment 7: The Consultant should provide slope ratio recommendations for temporary excavations and indicate on the geotechnical map areas where shoring is anticipated. CWE Response: We anticipate that the existing on-site soils will consist of Type C materials. Per OSHA Construction Standards temporary cut slopes in a Type C soil can be excavated at an inclination of 1 ½:1 (horizontal to vertical). The contractor is solely responsible for designing and constructing stable, temporary excavations and will need to shore, slope, or bench the sides of trench excavations as required to maintain the stability of the excavation sides. The contractor's "competent person", as defined in the .... ... .. .. ... .. .. ... ... ... ... .. 111111 ... .. -,.. ... ... ... ... ... .. ... ... ... -... ... ... CWE 2180441.07 February 14, 2020 Page No. 2 OSHA Construction Standards for Excavations, 29 CFR, Part 1926. Our firm should be contacted to observe all temporary cut slopes during grading to ascertain that no unforeseen adverse conditions exist. No surcharge loads such as foundation loads, or soil or equipment stockpiles, vehicles, etc. should be allowed within a distance from the top of temporary slopes equal to half the slope height. See attached Plate Nos. 2 and 3 for recommended cut slope parameters. The anticipated shoring limits had been previously delineated in the referenced report CWE 2180441.03 and reiterated on Plate No.1 ofthis report . City Comment 8: The Consultant should describe recommended foundation embedment materials ( compacted fill, paralic deposits, etc.) CWE Response: If our recommendations presented in our referenced geotechnical report (CWE 2180441.02) are followed we anticipate that the basement portion of the structure will be embedded in old paralic deposits whereas the at grade portion of the structure will be embedded in documented fills. Property line footings will also be embedded in old paralic deposits. City Comment 9: The Consultant should provide a list of recommendations for the geotechnical observation and testing during grading and construction . CWE Response: A geotechnical engineer shall be retained to observe and test the earthwork in accordance with the specifications presented in the referenced report CWE 2180441.02. This shall include but not be limited to the observation and/ or testing of fill placement, removal excavations, temporary cut slopes and foundation excavations. If you have any questions after reviewing this report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated . Respectfully submitted, CHRISTIAN WHEELER ENGINEERING Daniel B. Adler, RCE # 3603 7 Daniel J. Flowers, CEG # 2686 cc: hfgcck@gmail.com; luis@sdarchitccts.net; bardohno@plsacni,>inccring.com ' ::; r,, l I Anticipated-------s:--:,~::--CARL:-:-2:::-10--033-0=SBAO .. -::::::--O(J:::LVD;:--------------~l -...... -_-__ -_~J:--__ --------- " Shoring Limits ,A, wroooRsHOWERroeEcoVEREo .,,., I Jp."'· ,~,;t:1;c:,.~ ·,« ,,A'· ' B'f STAJRABOVE. DIWNTO BE TIED TO I/ ,~,6 ••.·, '"'., 'c'P~;R' : i PRl OPOSED RESIDENCE I "' ~,~-1 I ~ro~lJ-rN~µc'e H '.• '-' '.,' \ ·pl\,_ . ,__ ----'i :~.8 r:,~~---. \ ::; "' EUVGP~ . d E ··X·-~-v~-: ·--:-:, :"--54--Jl!;;jj!j SEWERLJNE i ~ ::; "' I ~ ... ·:·:.-.-·.· .. '::; 'l"s , ·: .• ·: :.·: ·1 ) _ __:j ·-.-rl ~~:~~ ~ /c, 1' SERVlCE ~ I ' NCHDRAIN 8; IE"47.7 SINGLE FAMILY RESIDE 1STFLDORFF=57.72 PAD• 56.97 PAO•l.7.1.7 7.5 ·, ,15l!AsEMENT LINE .....L.:---7 B' EMENT I\PN 21~20-00 5183 LOS ROBLES OR \! t. DR~~{.... f \ r-I EX.4.HPGAS 0 SERVICE Qop 7.0 ::; I ::; I ::; I ::; I ~ -~ ::; I TD BE"T'-. "I .. -;._.~.'°"•:•-,.,-. -,-,,.-,-'I REM~O ( " i .'\~ . .-t~-' (/} ; ~ 'o' • i i IE I "' ::; I ! / >-!. ~/k RFLok STRUCTUfl.E ! •. TG55.7 ! •. I IE52.1 i I "' I Y· G) (h ::; " ~, 4-,, WATER -~ ,--~-... .. NTION BASIN • ~-' ____ •. __ _ 54.6FG ~ I\PN21~--0(J 5184 CARLSBAD BLVD SITE PLAN AND GEOLOGIC MAP .. :, . .._ ,, I I FENCE TOBE AND STRUCTED . 18" CMU WALL REMAIN ': '/'ii',; t,!,/i Fe:;',;(J: :X;f';!'.if-~:"?: ,.Jc.I, i;t>t.; ( t.E:.'rf.:f~tJ.u,F~0 r_:r, 'N ~r<:.:tc·iCi VU[ / -r,; :. t.(:;... ~!'· A~Cl.·.f.f: DATE: BY: 0 20' 40' SCALE: 1" = 20' CWELEGEND $B-2 BORING LOCATIONS Qop OLD PARALIC DEPOSITS 1B B'I GEOLOGIC CROSS SECTION PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD AVENUE CARLSBAD, CALIFOfu'-JIA FEBRUARY 2020 JOB NO.: 2180441.07 SD PLATE NO.: WHEELER. EN Gi 'rER 1KG I I I Neighboring ~Residence '-PL I'-I I I A 60 -I I - Qop 50 .... 40 30 .... 1- 1 _ Existing _ I I Residence 7 Qop Proposed Residence 1st Floor Pad = 56.97' Existing Grade Proposed / Garage/Basement Pad = 47 .47' V L__ __ ---+ _ ____:::_ _______ _ B-2 Projected East 40' --B-1 Projected West 36' Neighboring Residence- PL I I V I / A' [ Anticip,<ed 1.5:1 (H:V) Temporary Cut Slope Projection Qop -60 50 40 30 L ____ ---1•--------:1:--'-----:;';---------!;;-----;;;------~6~0-----~,o,----sso20 WO ro W 30 40 50 CWELEGEND Qop Old Paralic Deposits GEOLOGIC CROSS SECTION A-A' DATE: BY: PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD AVENUE CARLSBAD, CALIFORNIA 0 FEBRUARY 2020 JOB NO.: 2180441.07 SD PLATE NO.: 2 10' 20' SCALE: 1" = 10' CHRISTIAN WHEELER ENGJNEERl 1'G I I I I I I I I I I I -E xisting Grade I-Proposed Residence --j 1st Floor Pad = 56.97' Garage/Basement Pad= 47.47' IL I Existing Residence I Existing Grade- Proposed Grade - Proposed -Spa PL I I I B 1 1-----FF = 57.4' ----j @ -I I J _l__--,---------7=::::h=::/~,=~tl= _____,fFJ==1 B' -@ 50 >- 40 ~ 30 20 O Qop 1 ___________ r--__________ P_ro_,p'--o_s_e_d_G_r_ad_e __________ ...v,, / / Anticipated Qop ' 10 --B-2 Projected Southwest 5' I 20 ' ' I 30 40 50 Qop ' ' @ 70 CWELEGEND Old Paralic Deposits 1.5:1 (H:V) Temporary Cut Slope Projection Qop ' ' 80 90 ---B-1 Projected N orthwest 25' I 100 50 40 30 ' 20 110 120 PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD AVENUE CARlSBAD, CALIFORNIA 0 GEOLOGIC CROSS SECTION B-B' DATE: FEBRUARY 2020 JOB NO.: 2180441.07 BY: SD PLATE 0.: 3 10' 20' SCALE: 1" = 10' CHRJSTIAN WHEELER E NGJNEE R I NG .... ... .. -... ... ... .. ... .. .. ... ... ... ... ... ... ... ... ,,,,. ... ... ... .. -... .. 111111 .. ... ... December 30, 2019 Paula Selvidge 2604 Trona Way Carlsbad, California 92009 • CHRJSTIAN WHEELER. ENGINEERING CWE 2180441.06 Subject: Limited Geotechnical Review of Shoring Plans and Site Retaining Walls Proposed Selvidge Residence, 5170 Carlsbad Boulevard, Carlsbad, California References: 1) Pasco Laret Suiter and Associates, Grading Plans for Selvidge Residence, undated 2) Shoring Design Group, Selvidge Residence, dated November 5, 2019 3) Christian Wheeler Engineering, Report CWE 2180441.02, dated September 21, 2018 Dear Mrs. Selvidge: At your request, we have performed a limited geotechnical review of the referenced grading plans and shoring plans for the subject project in order to ascertain that the recommendations presented in the referenced geotechnical report have been implemented, and that no additional recommendations are needed due to changes in the proposed construction. Based on this review, it is our opinion that, in general, the plans reflect the recommendations contained in the referenced report, and that no additional recommendations are necessary. It is our understanding that exterior miscellaneous retaining walls will be constructed using SDRSD standards. It is our opinion that these standards are applicable for the subject project. If you have any questions after reviewing this report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, CHRISTIAN W EELER ENGINEERING . l,RC® ec: hfgeek@gmail.com; luis@sdarchitects.net; bardolino@plsaengineering.com 3 9 8 0 H o m e ,,\ v e n u e ♦ S a n D i e go , C ,,\ 9 2 1 0 5 ♦ 6 1 9 -5 5 0 -1 7 0 0 ♦ F ,,\ X 6 1 9 -5 5 0 -1 7 0 1 ... ... ... .. ... ... .. -.. .. .. ... .. .. -.. ... .. -... ... ... ... ... ... ... ... ... ... ,. ... .. -- • CHRJSTIAN WHEELER. ENGINEERING REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD BOULEVARD CARLSBAD, CALIFORNIA PREPARED FOR: PAULA SELVIDGE 2604 TRONA WAY CARLSBAD, CALIFORNIA 92009 PREPARED BY: CHRISTIAN WHEELER ENGINEERING 3980 HOME A VENUE SAN DIEGO, CALIFORNIA 92105 3 9 8 0 H o m e A v e n u e ♦ S a n D i e go , C .\ 9 2 1 0 5 ♦ 6 1 9 -5 5 0 -1 7 0 0 ♦ F .\ X 6 1 9 -5 5 0 -1 7 0 1 -.. .. .. -.. ... ... .. .. ... ... .. ... -... ... --.. ... --... .. ... -.. .. .. .. .. -,. ... September 21, 2018 Paula Selvidge 2604 T rona Way Carlsbad, California 92009 • CHRJSTIAN WHEELER. ENGINEER.ING Subject: Report of Preliminary Geotechnical Investigation CWE 2180441.02 Proposed Selvidge Residence, 5170 Carlsbad Boulevard, Carlsbad, California Dear Mrs. Selvidge: In accordance with your request and our proposal dated August 1, 2018, we have completed a geotechnical investigation for the subject project. We are presenting herewith a report of our findings and recommendations . It is our professional opinion and judgment that no geotechnical conditions exist on the subject property that would preclude the construction of the proposed residence provided the recommendations presented herein are implemented . If you have questions after reviewing this report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated . Respectfully submitted, CH HEELER ENGINEERING an er, RCE #36037 DBA:djf ec: hfgeek@gmail.com zoltan@sdarchitects.net 9/21 ~18~;;;;:;;::::::. ..... 3980 Home Avenue ♦ San Diego, C.,\ 92105 ♦ 619-550-1700 + FAX 619-550-1701 ... -... -... ... ... -.. .. .. .. .. .. .. .. .. ... .. -... -.. -... ... .. ... ... .. .. .. ... .. .. ... TABLE OF CONTENTS Page Introduction and Project Description ..................................................................................................... 1 Scope of Services ..................................................................................................................................... 2 Findings .................................................................................................................................................. 3 Site Description ................................................................................................................................... 3 General Geology and Subsurface Conditions ...................................................................................... 3 Geologic Setting and Soil Description ............................................................................................. 3 Old Paralic Deposits .................................................................................................................... 4 Groundwater ................................................................................................................................... 4 Tectonic Setting ............................................................................................................................... 4 General Geologic Hazards .................................................................................................................. 5 General ............................................................................................................................................ 5 Surface Rupture ............................................................................................................................... 5 Slope Stability .................................................................................................................................. 5 Liquefaction ..................................................................................................................................... 5 Flooding .......................................................................................................................................... 5 Tsunamis ......................................................................................................................................... 5 Seiches ............................................................................................................................................. 6 Conclusions ............................................................................................................................................ 6 Recommendations .................................................................................................................................. 7 Grading and Earthwork ...................................................................................................................... 7 General ............................................................................................................................................ 7 Pregrade Meeting ............................................................................................................................. 7 Observation of Grading ................................................................................................................... 7 Clearing and Grubbing .................................................................................................................... 8 Site Preparation ............................................................................................................................... 8 Excavation Characteristics ............................................................................................................... 8 Processing of Fill Areas ................................................................................................................... 8 Compaction and Method of Filling .................................................................................................. 9 Surface Drainage .............................................................................................................................. 9 Temporary Cut Slopes ...................................................................................................................... 10 Temporary Shoring ........................................................................................................................... 10 General .......................................................................................................................................... 10 Foundations ...................................................................................................................................... 11 General .......................................................................................................................................... 11 Dimensions ................................................................................................................................ 11 Bearing Capacity ......................................................................................................................... 11 Footing Reinforcing .................................................................................................................... 11 Lateral Load Resistance ............................................................................................................... 11 Foundation Excavation Observation ............................................................................................... 12 Settlement Characteristics ............................................................................................................. 12 Expansive Characteristics ................................................................................................................ 12 Soluble Sulfates .............................................................................................................................. 12 Foundation Plan Review ................................................................................................................ 12 Seismic Design Factors .................................................................................................................. 13 CWE 2180441.02 Proposed Selvidge Residence 5170 Carlsbad Boulevard Carlsbad, California ... ... .. ... .. ... .. ... .. .. .. .. .. .. ... ... .. .. ... .. -.. ... ... ... ... ... ... .. .. ... ... .. ... On-Grade Slabs ................................................................................................................................. 13 General .......................................................................................................................................... 13 Interior Floor Slabs ......................................................................................................................... 14 Under-Slab Vapor Retarders .......................................................................................................... 14 Exterior Concrete Flatwork .......................................................................................................... 14 Earth Retaining Walls ....................................................................................................................... 15 Foundations ................................................................................................................................... 15 Passive Pressure ............................................................................................................................. 15 Active Pressure .............................................................................................................................. 15 Waterproofing and Wall Drainage Systems .................................................................................... 15 Backfill ........................................................................................................................................... 16 Limitations ........................................................................................................................................... 16 Review, Observation and Testing ..................................................................................................... 16 Uniformity of Conditions ................................................................................................................. 16 Change in Scope ................................................................................................................................ 17 Time Limitations .............................................................................................................................. 17 Professional Standard ........................................................................................................................ 17 Client's Responsibility ...................................................................................................................... 17 Field Explorations ................................................................................................................................ 18 Laboratory Testing ............................................................................................................................... 18 TABLES Table I Table II FIGURES Figure 1 PLATES Plate 1 Plate 2 APPENDICES Appendix A Appendix B Appendix C Appendix D ATTACHMENTS Shoring Design Parameters Seismic Design Parameters, 2016 CBC Site Vicinity Map, Follows Page 1 Site Plan & Geotechnical Map Retaining Wall Subdrain Subsurface Explorations Laboratory Test Results References Recommended Grading Specifications-General Provisions CWE 2180441.02 Proposed Selvidge Residence 5170 Carlsbad Boulevard Carlsbad, California -.. ... ... -.. .. .. .. .. -.. .. .. .. ... ... ... ... .. .. ... .... ... -.. .. .. .. .. ... ... .. - w CHRISTIAN WHEELER ENGINEERING PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD BOULEVARD CARLSBAD, CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of a preliminary geotechnical investigation performed for proposed residential structure to be located at 5170 Carlsbad Boulevard, Carlsbad, California. The following Figure No. 1 presents a vicinity map showing the location of the property . We understand that the existing structure and associated improvements on-site are to be demolished. A new two-and three-story residential structure that will include an underground level is proposed. We anticipate that the proposed structure will be of concrete and/ or masonry and wood-frame construction with on-grade concrete floor slabs, and will be supported by conventional shallow foundations. Grading to accommodate the proposed improvements is expected to consist of cuts of up to about 12 feet from existing site grade . To assist in the preparation of this report, we were provided with an undated set of miscellaneous plans prepared by Stephen Dalton Architects, and a topographic survey prepared by Baker Land Surveys, Inc., dated March 8, 2018. A copy of a site plan included in the set was used as a base map for our Site Plan and Geologic Map, and is included herein as Plate No. 1. This report has been prepared for the exclusive use of Paula Selvidge, and her design consultants, for specific application to the project described herein. Should the project be modified, the conclusions and recommendations presented in this report should be reviewed by Christian Wheeler Engineering for conformance with our recommendations and to determine whether any additional subsurface investigation, laboratory testing and/ or recommendations are necessary. Our professional services have been performed, our findings obtained and our recommendations prepared in accordance with 3 9 8 0 H o m e A v e n u e ♦ S a n D i e go , C ,-\ 9 2 1 0 5 ♦ 6 1 9 -5 5 0 -1 7 0 0 ♦ FA X 6 1 9 -5 5 0 -1 7 0 1 DATE: SEPTEMBER 2018 BY: SRO SITE VICINITY 0 OpenStreetMap contributors SELVIDGE RESIDENCE 5170 CARLSBAD AVENUE CARLSBAD, CALIFORNIA JOB NO.: FIGURE NO.: 2180441.02 ." CHRISTIAN WHEELER ENGINEE RING .. ... ... .. ... ... ... .. .. .. -.. -... .. .. ... .. ... ... .. ... .... ... .. ... ... ... ... .. .. .. .. ... .. ... CWE 2180441.02 September 21, 2018 Page No. 2 generally accepted engineering principles and practices. This warranty is in lieu of all other warranties, expressed or implied . SCOPE OF SER VICES Our preliminary geotechnical investigation consisted of surface reconnaissance, subsurface exploration, obtaining representative soil samples, laboratory testing, analysis of the field and laboratory data, and review of relevant geologic literature. Our scope of service did not include assessment of hazardous substance contamination, recommendations to prevent floor slab moisture intrusion or the formation of mold within the structures, evaluation or design of storm water infiltration facilities, or any other services no,t specifically described in the scope of services presented below. More specifically, the intent of our proposed investigation was to: • Drill two small diameter borings at the site with a limited access, tripod mounted drill rig to explore the existing soil conditions and obtain soil samples for laboratory testing . • Backfill the boring holes using a grout or a grout/bentonite mix as required by the County of San Diego Department of Environmental Health . • Evaluate, by laboratory tests and our past experience with similar soil types, the engineering properties of the various soil strata that may influence the proposed construction, including bearing capacities, expansive characteristics and settlement potential . • Describe the general geology at the site, including possible geologic hazards that could have an effect on the proposed construction, and provide the seismic design parameters as required by the 2016 edition of the California Building Code . • Address potential construction difficulties that may be encountered due to soil conditions, groundwater or geologic hazards, and provide geotechnical recommendations to deal with these difficulties . • Provide site preparation and grading recommendations for the anticipated work . • Provide shored and unshored temporary cut slope recommendations . • Provide foundation recommendations for the type of construction anticipated and develop soil engineering design criteria for the recommended foundation designs . • Provide design parameters for restrained and unrestrained retaining walls . -... ... ... ... ... ... -... .. -.. ... ... -.. ... ... ... ... ... ... -.. ... ... -... ... .. .. .. ---- CWE 2180441.02 September 21, 2018 Page No. 3 • Provide a preliminary findings and foundation recommendations report based on a site reconnaissance and our general knowledge of the geotechnical conditions in the site vicinity . • Provide a preliminary geotechnical report that presents the results of our investigation which includes a plot plan showing the location of our subsurface explorations, excavation logs, laboratory test results, and our conclusions and recommendations for the proposed project. Although a test for the presence of soluble sulfates within the soils that may be in contact with reinforced concrete was performed as part of the scope of our services, it should be understood Christian Wheeler Engineering does not practice corrosion engineering. If a corrosivity analysis is considered necessary, we recommend that the client retain an engineering firm that specializes in this field to consult with them on this matter. The results of our sulfate testing should only be used as a guideline to determine if additional testing and analysis is necessary . FINDINGS SITE DESCRIPTION The subject site is a rectangular-shaped, developed residential lot located at 5170 Carlsbad Boulevard, Carlsbad, California. The lot is bounded to the west by Carlsbad Boulevard, and is otherwise bounded by developed residential lots. The site currently supports a residential structure. Topographically, the majority of the site is flat-lying. Elevations range from about 55 feet along the western property line to about 58 feet at the southeastern corner of the site. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located in the Coastal Plains Physiographic Province of San Diego County. Based upon the findings of our subsurface explorations and review of readily available, pertinent geologic and geotechnical literature, it was determined that the site is generally underlain by old paralic deposits. These materials are described below: -.. ... .. ... .. -.. ... ... ... ... ... .... ... ... -- - (1111 ... -... --... .. ... .. ... -.. .. CWE 2180441.02 September 21, 2018 Page No. 4 OLD PARALIC DEPOSITS (Qop): Quaternary-age old paralic (marine terrace) deposits were found to underlie the subject site to a depth of about at least 19.5 feet from existing grade. As encountered in our borings, these materials generally consisted of light brown, orangish-brown, and brown, dry to moist, silty sand (SM) to a depth of about 9½ feet and 7 feet below existing grade, in borings B-1 and B-2, respectively. Below said depth the old paralic deposits consist of poorly graded sand with silt (SP-SM). The old paralic deposits in boring B-1 were found to be very dense. In boring B-2 the old paralic deposits were found to be medium dense to a depth of about 7 feet below existing grade. Below said depth these materials were dense, becoming very dense at a depth of about 17 feet below existing grade. The old paralic deposits judged to have a very low Expansion Index (EI< 20) . GROUNDWATER: No groundwater or seepage was encountered in our subsurface explorations. We do not expect any significant groundwater related conditions during or after the proposed construction . However, it should be recognized that minor groundwater seepage problems might occur after construction and landscaping are completed, even at a site where none were present before construction. These are usually minor phenomena and are often the result of an alteration in drainage patterns and/ or an increase in irrigation water. Based on the anticipated construction and the permeability of the on-site soils, it is our opinion that any seepage problems that may occur will be minor in extent. It is further our opinion that these problems can be most effectively corrected on an individual basis if and when they occur. TECTONIC SETTING: It should be noted that much of Southern California, including the San Diego County area, is characterized by a series of Quaternary-age fault zones that consist of several individual, en echelon faults that generally strike in a northerly to northwesterly direction. Some of these fault zones (and the individual faults within the zone) are classified as active while others are classified as only potentially active according to the criteria of the California Division of Mines and Geology. Active fault zones are those which have shown conclusive evidence of faulting during the Holocene Epoch (the most recent 11,000 years) while potentially active fault zones have demonstrated movement during the Pleistocene Epoch (11,000 to 1.6 million years before the present) but no movement during Holocene time. Inactive faults are those faults that can be demonstrated to have no movement in the past 1.6 million years . .. .. ... ... ... ... .. ... .. ... .. .. .. .. -... .. Ill .. ... ... .... ... ... ,.. ... ... ... ... ... ... .. .. .. ... .. ... CWE 2180441.02 September 21, 2018 Page No. 5 It should be recognized that the active Newport Inglewood-Rose Canyon Fault Zone is located approximately 2 miles northwest of the site. Other active fault zones in the region that could possibly affect the site include the Coronado Bank, San Diego Trough, and San Clemente Fault Zones to the west; the Palos Verdes Fault Zone to the northwest; and the Elsinore, San Jacinto and San Andreas Fault Zones to the northeast . GENERAL GEOLOGIC HAZARDS GENERAL: The site is located in an area where the risks due to significant geologic hazards are relatively low. No geologic hazards of sufficient magnitude to preclude the construction of the subject project are known to exist. In our professional opinion and to the best of our knowledge, the site is suitable for the proposed improvements. SURF ACE RUPTURE: There are no known active faults that traverse the subject site; therefore, the risk for surface rupture at the subject site is considered low. SLOPE STABILITY: As part of this investigation we reviewed the publication, "Landslide Hazards in the Northern Part of the San Diego Metropolitan Area" by Tan and Giffen, 1995. This reference is a comprehensive study that classifies San Diego County into areas of relative landslide susceptibility . The subject site is located in Area 2, which is considered to be "marginally susceptible" to slope failures . Based on our findings and the proposed construction, it is our opinion that the likelihood of slope stability related problems at the site is low. LIQUEFACTION: The earth materials underlying the site are not considered subject to liquefaction due to such factors as soil density, grain-size distribution, the absence of shallow groundwater conditions . FLOODING: As delineated on the Flood Insurance Rate Map (FIRM), panel 06073C0764G prepared by the Federal Emergency Management Agency, the site is located within a minimal flood hazard area . TSUNAMIS: Tsunamis are great sea waves produced by a submarine earthquake, submarine landslides or volcanic eruption. Historically, the San Diego area has been relatively free of tsunami- .. .. ... ... .. ... .. .. .. .. .. ... .. 11111 -... ... ... --... ... .. .... .... ... .. ... ... .. .. .. .. Ill .. ... .. 111111 CWE 2180441.02 September 21, 2018 Page No. 6 related hazards and tsunamis reaching San Diego have generally been well within the normal tidal range. It is thought that the wide continental margin off the coast acts to diffuse and reflect the wave energy of remotely generated tsunamis. The largest historical tsunami to reach San Diego's coast was 4.6 feet high, generated by the 1960 earthquake in Chile. A lack of knowledge about the offshore fault systems makes it difficult to assess the risk due to locally generated tsunamis . The site is loacted above the Tsunami Inundation area and Inundation Line as presented on the Oceanside and San Luis Rey Quadrangles of the Tsunami Inundation Map for Emergency Planning (CalEMA, 2009). Furthermore, given the elevation of the site, the risk of damage to the proposed site improvements from a tsunamis is considered to be low . SEICHES: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or reservoirs. Due to the site's location, it will not be affected by seiches . CONCLUSIONS In general, it is our professional opinion and judgment that the subject property is suitable for the construction of the proposed structure provided the recommendations presented herein are implemented. The main geotechnical conditions affecting the proposed project consist of potentially compressible old paralic deposits, a cut/fill transition under the proposed structure, and temporary cut slopes. These conditions are discussed hereinafter . The site is underlain by a relatively thin layer of potentially compressible old paralic deposits. As encountered in our subsurface explorations, these materials extend to a maximum depth of about 2 feet from existing grade (boring B-2). However, they may be deeper in areas of the site not investigated . These soils are considered unsuitable, in their present condition, for the support of settlement sensitive improvements. The potentially compressible materials will require removal and replacement as compacted fill where underling proposed settlement sensitive improvements. In addition, the old paralic deposits in boring B-2, although medium dense, were found to be significantly less dense than those encountered in boring B-1. Furthermore, some of the old paralic deposits may be collapsible. In order to provide for a more homogeneous foundation soil condition, it is recommended that these materials be removed as recommend hereinafter. It is anticipated that some of these materials will be removed as part of the proposed grading . t •• ... .. .. .. ... .. ... ... .. .. -.. .. 1111 .. -.. .. ... .. ... ... ... ... .. ... ... --... ... .. ... .. Ill' ... .. CWE 2180441.02 September 21, 2018 Page No. 7 A cut-fill transition will occur under the proposed structure due to the recommended site preparation and proposed grading. Cut-fill transitions may result in differential settlements detrimental to the propose structure. In order to mitigate this condition, special site preparation consideration is recommended hereinafter . Temporary cut slopes up to about 12 feet in depth (including footing excavation) are anticipated for the proposed basement construction. Due to the characteristics of some of the old paralic deposits, flatter than usual temporary cut slopes are recommended. In addition, it is anticipated that some temporary shoring may be necessary for proposed basement construction . The site is located in an area that is relatively free of geologic hazards that will have a significant effect on the proposed construction. The most likely geologic hazard that could affect the site is ground shaking due to seismic activity along one of the regional active faults. However, construction in accordance with the requirements of the most recent edition of the California Building Code and the local governmental agencies should provide a level of life-safety suitable for the type of development proposed . RECOMMENDATIONS GRADING AND EARTHWORK GENERAL: All grading should conform to the guidelines presented in the current edition of the California Building Code, the minimum requirements of the City of Carlsbad, and the recommended Grading Specifications and Special Provisions attached hereto, except where specifically superseded in the text of this report . PREGRADE MEETING: It is recommended that a pre-grade meeting including the grading contractor, the client, and a representative from Christian Wheeler Engineering be performed, to discuss the recommendations of this report and address any issues that may affect grading operations . OBSERVATION OF GRADING: Continuous observation by the Geotechnical Consultant is essential during the grading operation to confirm conditions anticipated by our investigation, to allow ... ... ... .. .. -.. .. ... ... .. -... ... .... .... ... ... ... ... ... ... .. ,. ... .. .. .. CWE 2180441.02 September 21, 2018 Page No. 8 adjustments in design criteria to reflect actual field conditions exposed, and to determine that the grading proceeds in general accordance with the recommendations contained herein. CLEARING AND GRUBBING: Site preparation should begin with the demolition of existing improvements. The resulting debris and any existing vegetation and other deleterious materials in areas to receive proposed improvements or new fill soils should be removed from the site . SITE PREPARATION: It is recommended that potentially compressible and collapsible old paralic deposits as well as soils disturbed during demolition underlying the proposed structure, associated improvements, and new fills should be removed and replaced as compacted fill. Based on our findings, it is anticipated that the maximum removal depth will be about 2 feet below existing grade. In addition, old paralic deposits within 4 feet from existing or proposed grade should be undercut. This recommendation does not apply to the basement portion of the structure. Deeper removals may be necessary in areas of the site not investigated or due to unforeseen conditions. Lateral removal limits should extend at least 5 feet from the perimeter of the structure, any settlement sensitive improvements, and new fills or equal to removal depth, whichever is more. No removals are recommended beyond property lines. The removals and undercuts should be performed in such a way as to provide for a continuous contact between the fill and old paralic deposits that drains away from the proposed structure, and avoids adjacent zones with different undercut depths that may impair subsurface drainage. All excavated areas should be approved by the geotechnical engineer or his representative prior to replacing any of the excavated soils. The excavated materials can be replaced as properly compacted fill in accordance with the recommendations presented in the "Compaction and Method of Filling" section of this report . EXCAVATION CHARACTERISTICS: The old paralic deposits underlying the site at proposed basement elevations was found to be in a very dense condition. In addition, some of these materials are friable. It is anticipated that excavations in these materials may be performed with heavy duty conventional grading equipment. However, excavations with light trenching equipment may be difficult . PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constructing any new improvements in areas that have been cleaned out to receive fill, the exposed soils should be scarified -... -.. ... .. ... ... ... ... .. .. ... .. .. .. ... .. ... .... ... ... - ... .. .. ... .. 1111 .. -.. .. .. CWE 2180441.02 September 21, 2018 Page No. 9 to a depth of 12 inches, watered thoroughly, and compacted to at least 90 percent relative compaction . This recommendation applies to the area of the site outside the perimeter of the proposed basement . COMPACTION AND METHOD OF FILLING: In general, all structural fill placed at the site, including should be compacted to a relative compaction of at least 90 percent of its maximum laboratory dry density as determined by ASTM Laboratory Test D1557. However, retaining wall backfill and structural fill underlying the proposed structure should be compacted to at least 95%. Fills should be placed at or slightly above optimum moisture content, in lifts six to eight inches thick, with each lift compacted by mechanical means. Fills should consist of approved earth material, free of trash or debris, roots, vegetation, or other materials determined to be unsuitable by the Geotechnical Consultant. Fill material should be free of rocks or lumps of soil in excess of 3 inches in maximum dimension . Utility trench backfill within 5 feet of the proposed structure and beneath all concrete flatwork or pavements should be compacted to a minimum of 90 percent of its maximum dry density . SURFACE DRAINAGE: The drainage around the proposed improvements should be designed to collect and direct surface water away from proposed improvements toward appropriate drainage facilities. Rain gutters with downspouts that discharge runoff away from the structure into controlled drainage devices are recommended . The ground around the proposed improvements should be graded so that surface water flows rapidly away from the improvements without ponding. In general, we recommend that the ground adjacent to structure slope away at a gradient of at least 5 percent for a minimum distance of 10 feet. If the minimum distance of 10 feet cannot be achieved, an alternative method of drainage runoff away from the building at the termination of the 5 percent slope will need to be used. Swales and impervious surfaces that are located within 10 feet of the building should have a minimum slope of 2 percent. Pervious hardscape surfaces adjacent to structures should be similarly graded . Drainage patterns provided at the time of construction should be maintained throughout the life of the proposed improvements. Site irrigation should be limited to the minimum necessary to sustain landscape growth. Over watering should be avoided. Should excessive irrigation, impaired drainage, or unusually high rainfall occur, zones of wet or saturated soil may develop . ... ... -... ... ... ... ... .. .. .. .. .. .. .. .. .. .. .. ... ... ... ... ... ... ... .... ... ,. .. ,.. .. -- CWE 2180441.02 September 21, 2018 Page No. 10 TEMPORARY CUT SLOPES The contractor is solely responsible for designing and constructing stable, temporary excavations and will need to shore, slope, or bench the sides of trench excavations as required to maintain the stability of the excavation sides. The contractor's "competent person", as defined in the OSHA Construction Standards for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety process. We anticipate that the existing on-site soils will consist of Type C material. Our firm should be contacted to observe all temporary cut slopes during grading to ascertain that no unforeseen adverse conditions exist. No surcharge loads such as foundation loads, or soil or equipment stockpiles, vehicles, etc. should be allowed within a distance from the top of temporary slopes equal to half the slope height . TEMPORARY SHORING GENERAL: Shoring may be necessary for the proposed construction. It is anticipated that the shoring system will utilize soldier beams with wooden lagging. The following design parameters may be assumed to calculate earth pressures on shoring . Angle of friction 30° Apparent cohesion 200 pounds per square foot Soil unit weight 115 pounds per cubic foot (pct) Active pressures can be applied to shoring that is capable of rotating 0.002 radians. At-rest pressures should be applied to a shoring system that is unyielding and not able to rotate. These values do not include surcharge loads. Construction surcharge loads should be evaluated on a case-by-case basis . Vertical and lateral movements of the temporary shoring are expected to be small assuming an adequate lateral support system. ... .. ... ... ... ... .. .. .. .. .. ... ... .. .. -11111 .. ... .. .... ... .. ... .. ... .. -.. .. .. .. ... 11111 .. ... CWE 2180441.02 September 21, 2018 Page No. 11 FOUNDATIONS GENERAL: Based on our findings and engineering judgment, the proposed structure may be supported by conventional shallow continuous and isolated spread footings. The following recommendations are considered the minimum based on the anticipated soil conditions, and are not intended to be lieu of structural considerations. All foundations should be designed by a qualified engmeer . DIMENSIONS: Spread footings supporting the proposed structure should be embedded at least 18 inches below lowest adjacent finish pad grade. Spread footings supporting light miscellaneous exterior footings should be embedded at least 12 inches below lowest adjacent finish pad grade. Continuous and isolated footings should have a minimum width of 12 inches and 24 inches, respectively. Retaining wall footings should be at least 18 inches deep and 24 inches wide. Property line footings should also extend at least 6 inches into competent old paralic deposits. BEARING CAPACITY: Spread footings supporting the proposed structure with a minimum depth of 18 inches and a minimum width of 12 inches may be designed for an allowable soil bearing pressure of 2,000 pounds per square foot (psf). This value may be increased by 600 pounds per square foot for each additional foot of embedment and 400 pounds per square foot for each additional foot of width up to a maximum of 4,000 pounds per square foot. These values may be increased by one-third for combinations of temporary loads such as those due to wind or seismic loads . FOOTING REINFORCING: Reinforcement requirements for foundations should be provided by a structural designer. However, based on the expected soil conditions, we recommend that the minimum reinforcing for continuous footings consist of at least 2 No. 5 bars positioned near the bottom of the footing and 2 No. 5 bars positioned near the top of the footing . LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction between the bottom of the footing and the supporting soil, and by the passive pressure against the footing. The coefficient of friction between concrete and soil may be considered to be 0.30. The passive resistance may be considered to be equal to an equivalent fluid weight of 300 pounds per cubic foot . These values are based on the assumption that the footings are poured tight against undisturbed soil. If a --... ... ... ... ,.. ... ... .. .. .. .. ... .. ... .. ... --... 1111111 ... .. ... ,.. .... ... ... .. .. .. ... .. .. .. .. CWE 2180441.02 September 21, 2018 Page No. 12 combination of the passive pressure and friction is used, the friction value should be reduced by one- third . FOUNDATION EXCAVATION OBSERVATION: All footing excavations should be observed by Christian Wheeler Engineering prior to placing of forms and reinforcing steel to determine whether the foundation recommendations presented herein are followed and that the foundation soils are as anticipated in the preparation of this report. All footing excavations should be excavated neat, level, and square. All loose or unsuitable material should be removed prior to the placement of concrete . SETTLEMENT CHARACTERISTICS: The anticipated total and differential settlement is expected to be less than about 1 inch and 1 inch over 40 feet, respectively, provided the recommendations presented in this report are followed. It should be recognized that minor cracks normally occur in concrete slabs and foundations due to concrete shrinkage during curing or redistribution of stresses, therefore some cracks should be anticipated. Such cracks are not necessarily an indication of excessive vertical movements . EXPANSIVE CHARACTERISTICS: The prevailing foundation soils are assumed to have a very low expansive potential (EI< 20). The recommendations within this report reflect these conditions . SOLUBLE SULFA TES: The water soluble sulfate content of a selected soil sample from the site was determined in accordance with California Test Method 417. The test results indicate that the soil sample had a soluble sulfate content of 0.006 percent. Soils with a soluble sulfate content of less than 0.1 percent are considered to be negligible. However, it should be recognized that the sulfate content of surficial soils may increase with time due to soluble sulfate in the irrigation water or fertilized use. FOUNDATION PLAN REVIEW: The final foundation plan and accompanying details and notes should be submitted to this office for review. The intent of our review will be to verify that the plans used for construction reflect the minimum dimensioning and reinforcing criteria presented in this section and that no additional criteria are required due to changes in the foundation type or layout. It is not our intent to review structural plans, notes, details, or calculations to verify that the design engineer has correctly applied the geotechnical design values. It is the responsibility of the design engineer to -.. ... -... .. ... .. ... Ill -.. .. ... .. .. .. ... .. .. ... .... .... ... -... ... ... .. ... .. Ill .. .. ... ... .... CWE 2180441.02 September 21, 2018 Page No. 13 properly design/ specify the foundations and other structural elements based on the requirements of the structure and considering the information presented in this report . SEISMIC DESIGN FACTORS The seismic design factors applicable to the subject site are provided below. The seismic design factors were determined in accordance with the 2016 California Building Code. The site coefficients and adjusted maximum considered earthquake spectral response acceleration parameters are presented in the following Table I. TABLE II: SEISMIC DESIGN FACTORS Site Coordinates: Latitude 33.131 ° Longitude -117.334° Site Class D Site Coefficient Fa 1.031 Site Coefficient Fv 1.549 Spectral Response Acceleration at Short Periods S, 1.173 g Spectral Response Acceleration at 1 Second Period S1 0.451 g SMs=FaSs 1.209 g SM1=FvS1 0.699 g Sos=2/3*SMs 0.806 g S01 = 2/ 3 '~SM! 0.446 g Probable ground shaking levels at the site could range from slight to moderate, depending on such factors as the magnitude of the seismic event and the distance to the epicenter. It is likely that the site will experience the effects of at least one moderate to large earthquake during the life of the proposed improvements . ON-GRADE SLABS GENERAL: It is our understanding that the floor system of the proposed structure will consist of a concrete slab-on-grade. The following recommendations are considered the minimum slab requirements based on the soil conditions and are not intended in lieu of structural considerations. These recommendations assume that the site preparation recommendations contained in this report are implemented . ... ... ... ... .. ... .. .. -.. .. ... ... .. ... ... ... ... ... ,.. ... ... ... ... ... .. .. .. ... .. ... CWE 2180441.02 September 21, 2018 Page No. 14 INTERIOR FLOOR SLABS: The minimum basement slab thickness should be 4 inches (actual) and the slab should be reinforced with at least No. 3 bars spaced at 18 inches on center each way. The minimum slab thickness for the on-grade portion of the structure should be 5 inches (actual) and the slab should be reinforced with at least No. 4 bars spaced at 18 inches on center each way. Slab reinforcement should be supported on chairs such that the reinforcing bars are positioned at mid- height in the floor slab. The slab reinforcement should extend down into the perimeter footings at least 6 inches . UNDER-SLAB VAPOR RETARDERS: Steps should be taken to minimize the transmission of moisture vapor from the subsoil through the interior slabs where it can potentially damage the interior floor coverings. Local industry standards typically include the placement of a vapor retarder, such as plastic, in a layer of coarse sand placed directly beneath the concrete slab. Two inches of sand are typically used above and below the plastic. The vapor retarder should be at least 15-mil Stegowrap® or similar material with sealed seams and should extend at least 12 inches down the sides of the interior and perimeter footings. The sand should have a sand equivalent of at least 30, and contain less than 10% passing the Number 100 sieve and less than 5% passing the Number 200 sieve. The membrane should be placed in accordance with the recommendation and consideration of ACI 302, "Guide for Concrete Floor and Slab Construction" and ASTM E1643, "Standards Practice for Installation of Water Vapor Retarder Used in Contact with Earth or Granular Fill Under Concrete Slabs." It is the flooring contractor's responsibility to place floor coverings in accordance with the flooring manufacturer specifications . EXTERIOR CONCRETE FLA TWORK: Exterior concrete slabs on grade should have a minimum thickness of 4 inches and be reinforced with at least No. 4 bars placed at 18 inches on center each way (ocew). Driveway slabs should have a minimum thickness of 5 inches and be reinforced with at least No. 4 bars placed at 12 inches ocew. Driveway slabs should be provided with a thickened edge a least 12 inches deep and 6 inches wide. Special consideration is needed to slabs adjacent to swimming pools and spas due to potential chloride exposure. All slabs should be provided with weakened plane joints in accordance with the American Concrete Institute (ACI) guidelines. Special attention should be paid to the method of concrete curing to reduce the potential for excessive shrinkage cracking. It should be recognized that minor cracks occur normally in concrete slabs due to shrinkage. Some shrinkage -... ... ... ... ... ... -... ... .... .. ... ... ... ... ... ... ... ... ... .. ... .. .. .. -.. 1111 CWE 2180441.02 September 21, 2018 Page No. 15 cracks should be expected and are not necessarily an indication of excessive movement or structural distress . EARTH RETAINING WALLS FOUND A TIO NS: Foundations for any proposed retaining walls should be constructed in accordance with the foundation recommendations presented previously in this report . PASSIVE PRESSURE: The passive pressure for the anticipated foundation soils may be considered to be 300 pounds per square foot per foot of depth. The upper foot of embedment should be neglected when calculating passive pressures, unless the foundation abuts a hard surface such as a concrete slab. The passive pressure may be increased by one-third for seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.30 for the resistance to lateral movement. When combining frictional and passive resistance, the friction should be reduced by one-third . ACTIVE PRESSURE: The active soil pressure for the design of "unrestrained" and "restrained" earth retaining structures with level backfill may be assumed to be equivalent to the pressure of a fluid weighing 40 and 60 pounds per cubic foot, respectively. These pressures do not consider any other surcharge. If any are anticipated, this office should be contacted for the necessary increase in soil pressure. These values are based on a drained backfill condition. Seismic lateral earth pressures may be assumed to equal an inverted triangle starting at the bottom of the wall with the maximum pressure equal to 9.SH pounds per square foot (where H = wall height in feet) occurring at the top of the wall. WATERPROOFING AND WALL DRAINAGE SYSTEMS: The need for waterproofing should be evaluated by others. If required, the project architect should provide (or coordinate) waterproofing details for the retaining walls. The design values presented above are based on a drained backfill condition and do not consider hydrostatic pressures. The retaining wall designer should provide a detail for a wall drainage system. Typical retaining wall drain system details are presented as Plate No . 2 of this report for informational purposes. Additionally, outlets points for the retaining wall drain system should be coordinated with the project civil engineer . _____ * __ 1,,_ ... .. ... ... ... ... ... ... ... ... ... ... ... ... ... .. ... ... ... ... ... ... ... ... ... ... ... ... ... .. .. ---.. .. CWE 2180441.02 September 21, 2018 Page No. 16 BACKFILL: Retaining wall backfill soils should be compacted to at least 90 percent relative compaction. However, retaining wall backfill underlying settlement sensitive improvements should be compacted to at least 95%.Expansive or clayey soils should not be used for backfill material. The wall should not be backfilled until the masonry has reached an adequate strength . LIMITATIONS REVIEW, OBSERVATION AND TESTING The recommendations presented in this report are contingent upon our review of final plans and specifications. Such plans and specifications should be made available to the geotechnical engineer and engineering geologist so that they may review and verify their compliance with this report and with the California Building Code . It is recommended that Christian Wheeler Engineering be retained to provide continuous soil engineering services during the earthwork operations. This is to verify compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction . UNIFORMITY OF CONDITIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface exploration locations and on the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/ or cut and fill slopes may be influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the geotechnical engineer so that he may make modifications if necessary . ... ... .... ... ... ... ... ... .. ... .. .. ... ... ... ... .. .... Ill"' ... ... ... ... ... Ill"' ... ... .. ... ... .. .. ... .. CWE 2180441.02 September 21, 2018 Page No. 17 CHANGE IN SCOPE This office should be advised of any changes in the project scope or proposed site grading so that we may determine if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum . TIME LIMITATIONS The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in the Standards-of-Practice and/ or Government Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two years without a review by us verifying the suitability of the conclusions and recommendations . PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession currently practicing under similar conditions and in the same locality. The client recognizes that subsurface conditions may vary from those encountered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations, and recommendations be based solely on the information obtained by us. We will be responsible for those data, interpretations, and recommendations, but shall not be responsible for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, express or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or written reports or findings . CLIENT'S RESPONSIBILITY It is the responsibility of the Client, or her representatives, to ensure that the information and recommendations contained herein are brought to the attention of the structural engineer and ... .. 1111 ... ... 11111 ... ... ... .. ... .. .. ... .. ... .. ... ... .. .... .... .. ... .... .... .... .. .... .... ,.. .... ... ... ... .... ... .... CWE 2180441.02 September 21, 2018 Page No. 18 architect for the project and incorporated into the project's plans and specifications. It is further their responsibility to take the necessary measures to insure that the contractor and his subcontractors carry out such recommendations during construction. FIELD EXPLORATIONS Two subsurface explorations were made on August 13, 2018 at the locations indicated on the Site Plan and Geotechnical Map included herewith as Plate No. 1. These explorations consisted of small diameter borings drilled utilizing a portable drill rig. The fieldwork was conducted under the observation and direction of our engineering geology personnel. The explorations were carefully logged when made. The boring logs are presented on Appendix A. The soils are described in accordance with the Unified Soils Classification. In addition, a verbal textural description, the wet color, the apparent moisture, and the density or consistency is provided. The density of granular soils is given as very loose, loose, medium dense, dense or very dense. The consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff, or hard . Relatively undisturbed drive samples were collected using a modified California sampler. The sampler, with an external diameter of 3.0 inches, is lined with 1-inch long, thin, brass rings with inside diameters of approximately 2.4 inches. The sample barrel was driven into the ground with the weight of a 140-pound hammer falling 30 inches in general accordance with ASTM D 3550-84. The driving weight is permitted to fall freely. The number of blows per foot of driving, or as indicated, are presented on the boring logs as an index to the relative resistance of the sampled materials. The samples were removed from the sample barrel in the brass rings, and sealed. Bulk samples of the earth materials encountered were also collected. Samples were transported to our laboratory for testing . LABO RA TORY TESTING Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (ASTM) test methods or suggested procedures. A brief description of the tests performed and the subsequent results are presented in Appendix B . I I EXISTING SINGLE FAMILY RESIDENCE EXISTING SINGLE FAMILY RESIDENCE G)-PROPOSE~D~Sl~T=E~P~LA~N~----------------- SITE PLAN AND GEOLOGIC MAP DATE: BY: I 0 20' 40' SCALE: 1" = 20' CWELEGEND SB-2 BORING LOCATIONS Qop OLD PARALIC DEPOSITS PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD A VENUE CARLSBAD, CALIFORNIA SEPTEMBER 2018 JOB NO.: SD PLATE NO.: 2180441.02 eet A0-1 78 CHR.ISTIAN WHEELER. l:NCI N LI.RI NG .. ... .... ... ... .. .. ... .. ... ... .. .... .... ... ... ' ... .. .. ... .. ... .. ... 111111 ... 6"MIN. 12"MIN. r 5 G) G)12" m DETAIL [I] DETAIL 6"MIN. 6"MIN . 5 5 G) G) G)12·· G)12" 7 [I] DETAIL 8J DETAIL NOTES AND DETAILS GENERAL NOTES: I) THE NEED FOR WATERPROOFING SHOULD BE EVALUATED BY OTHERS. 2) WATERPROOFING TO BE DESIGNED BY OTHERS (CWE CAN PROVIDE A DESIGN IF REQUESTED) . 3) EXTEND DRAIN TO SUITABLE DISCHARGE POINT PER CIVIL ENGINEER. 4) DO NOT CONNECT SURFACE DRAINS TO SUBDRAIN SYSTEM . DETAILS: CD 0 4-INCH PERFORATED PVC PIPE ON TOP OF FOOTING, HOLES POSITIONED DOWNWARD (SDR 35, SCHEDULE 40, OR EQUIVALENT). ¾ INCH OPEN-GRADED CRUSHED AGGREGATE. CD GEOFARBRIC WRAPPED COMPLETEL y AROUND ROCK. G) ® PROPERLY COMPACTED BACKFILL SOIL. WALL DRAINAGE PANELS (MIRADRAIN OR EQUIVALENT) PLACED PER MANUFACTURER'S REC'S. © 0 UNDERLAY SUBDRAIN WITH AND CUT FABRIC BACK FROM DRAINAGE PANELS AND WRAP FABRIC AROUND PIPE. COLLECTION DRAIN (TOT AL DRAIN OR EQUIVALENT) LOCATED AT BASE OF WALL DRAINAGE PANEL PER MANUFACTURER'S RECOMMENDATIONS. CANTILEVER RETAINING WALL DRAINAGE SYSTEMS PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD A VENUE CARLSBAD, CALIFORNIA w DATE: SEPTEMBER 2018 BY: SRO JOB NO.: PLATE NO.: 2180441.02 2 CHRISTIAN WHEELER ENGINEERING ... .. .. .. .. .. --.. .. .. .. ..... Ill .. .. ... .. ... .... ,.. .. ... ... ... .. .. .. ... .. .. ... Appendix A Sub surf ace Explorations .. .. -LOG OF TEST BORING B-1 Sam2le Tl'.l?e and Laborato!l'. Test Le~nd Cal Modified California Sampler CK Chunk SPT Standard Penetration Test DR Drive Ring ST Shelby Tube Date Logged: 8/13/18 Equipment: Tripod MD Mu Density DS Direct Shear .. Logged By: DJF Bucket Ty;e: 6" Solid Flight S04 Soluble Sulfates Con Consolidation SA Sieve Analysis EI Expansion Index -Existing Elevation: Proposed Elevation: 57.0 feet Drive Type: 140lbs/30" drop 48.0 feet Depth to Water: NIA HA Hydrometer R-Val Resistance Value SE Sand Equivalent Chi Soluble Chlorides PI Plasticity Index Res pH & Resistivity SD ------.----.-----,..----,-----------------------------+---,----,--T"--CP Collapse Potential Sample Density 1111 ... .. .. .. .. -.. -... .. -.. .. .. .. ,,,, ... ... ... .. .. .. -.. ... ... ... ... g g ~ i::: i= ~ !ii 0 l'-l 0 -- -- -- --- 5-- -- -- -- -- 10-- -- -- --- -- 15-- -- -- -- -- 20-- -- -- -- -- 25-- -- -- -- --- 30-- Notes: --- ~ _y '' * ** : .. r~ltf .. :.;... ,· ~- ;.:h -,~·., mun ifo{( SM SM- SP SUMMARY OF SUBSURFACE CONDITIONS (based on Unified Soil Classification System) Old Paralic D9?osits (Qol?): Light brown, dry, loose to medium dense, very fine-to medium-grained, SIL TY SAND, upper 12" highly weathered. Orangish-brown, damp, very dense. Light brown to light orangish-brown, damp, very dense, very fine-to medium-grained, poorly-graded SAND with silt, friable. Boring terminated at 16.5 feet. No groundwater or seepage encountered. z ...- ~j ~~ ~l ~e 50/5" 50/5" 50/6" 50/6" Symbol Legend PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD A VENUE CARLSBAD, CALIFORNIA Groundwater Level During Drilling l'-l ~ ~ i=.. ~ "' Cal Cal Cal Cal Groundwater Level After Drilling Apparent Seepage DATE: SEPTEMBER 2018 JOB NO.: 2180441.02 No Sample Recovery Non-Representative Blow Count rocks oresent\ BY: SRO APPENDIX: A-1 i l t: ~ ~ ~~ "' ~~ s ~,;:;-Q,E, ~~ :s ~ '"' Oo ~ 3~ ): u 0 ~u~ 4.6 100.7 CP 3.2 103.6 CP 103.4 w CHR.lSTIAN WHEELER. [NGINE[IUNG -.. ... .. LOG OF TEST BORING B-2 Date Logged: Logged By: Existing Elevation: Proposed Elevation: 8/13/18 DJF 56.0 feet 48.0 feet Equipment: Bucket Ty;e: Drive Type: Depth to Water: Tripod 6" Solid Flight 140lbs/30" drop NIA Sample Type and Laboratory Test Legend Cal Modified California Sampler CK Chunk SPT Standard Penetration Test DR Drive Ring ST Shelby Tube MD Max Density DS Direct Shear S04 Soluble Sulfates Con Consolidation SA Sieve Analysis EI Expansion Index HA Hydrometer R-Val Resistance Value SE Sand Equivalent Chi Soluble Chloride, PI Plasticity Index Res pH & Resistivity CP Collapse Potential SD Sample Density ------,,------.---.-------.-----------------------------+------.-------.--..---..---..---..---• ... .. ... .. - (11111 .. -.. .. .. ... 0 5 15 20 25 30 Notes: * ** r~lff ·-.;, :.--~-:i ri~1'.W .. .. ::.:--.,:·. \.~·-~·;\ l~lt{ SM SP- SM SUMMARY OF SUBSURFACE CONDITIONS (based on Unified Soil Classification System) Old Paralic Deposits (Qop) : Brown, dry, loose to medium dense, very fine-to medium-grained, SIL TY SAND, upper 2' highly weathered. Light brown, damp, medium dense. Light brown to light orangish-brown, damp to moist, dense, very fine-to medium-grained, poorly-graded, SAND with silt, friable. Very dense . Boring terminated at 19 .5 feet. No groundwater or seepage encountered . Symbol Legend PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD AVENUE CARLSBAD, CALIFORNIA Groundwater Level During Drilling Groundwater Level After Drilling Apparent Seepage DATE: SEPTEMBER 2018 JOB NO.: 27 17 39 42 Cal 64 Cal 2180441.02 No Sample Recovery Non-Representative Blow Count rocks resent BY: SRD APPENDIX: A-2 108.8 112.7 4.0 104.7 3.8 110.2 • SA MD S04 DS DS SA SD SD SD CHR.lSTIAN WHEELER. ENGINEER.ING - ... -- ... --.. .. -... .. -.. -.. ,. ... ... ... .. --.. ,. ... -.. .. -.. .. .. .. -... Appendix B Laboratory Test Results -... ... ... ... .. ---.. --.. .. -.. .. ... ... ... .. ... ... ... --... ... .. .. -... .. --... Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (ASTM) test methods or suggested procedures. Brief descriptions of the tests performed are presented below: a) CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The final soil classifications are in accordance with the Unified Soil Classification System and are presented on the exploration logs in Appendix A. b) MOISTURE-DENSITY: MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for selected soil samples in accordance with ATM D 2937. The results are summarized in the boring logs presented in Appendix A. c) MAXIMUM DRY DENSITY AND OPTIUM MOISTURE CONTENT TEST: The maximum dry density and optimum moisture content of a selected soil sample were determined in the laboratory in accordance with ASTM D 1557, Method A. d) DIRECT SHEAR: Direct shear tests were performed on selected samples of the on-site soils in accordance with ASTM D 3080 . e) GRAIN SIZE DISTRIBUTION: The grain size distribution of selected samples was determined in accordance with ASTM C136 and/or ASTM D 422. t) COLLAPSE POTENTIAL: Collapse potential tests were performed on selected undisturbed soil samples in accordance with ASTM D 5333 . g) SOLUBLE SULFATES: The soluble sulfate content of a selected soil sample was determined in accordance with California Test Method 417 . w CHRISTIAN WHEELER I N <; I N I I R. I N c; PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD AVENUE, CARLSBAD LAB SUMMARY BY: DBA I DA TE: SEPT 2018 I REPORT NO.:2180441.02 I FIGURE NO.: B-1 .. --.. .. -... -... .. .. ... -.. --.. -.. -... ---... ... ... -.. .. .. .. .. -.. .. -... LABORATORY TEST RESULTS PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD AVENUE CARLSBAD, CALIFORNIA MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557) Sample Location Sample Description Maximum Density Optimum Moisture Boring B-2 @ 0-5' Brown Silty Sand (SM) 122.5 pcf 9.2 % DIRECT SHEAR (ASTM D3080) Sample Location Sample Type Friction Angle Cohesion Boring B-2 @ 0-5' Remolded to 90% 30° Boring B-2 @ 0-5' Undisturbed 30° 200 psf 200 psf GRAIN SIZE DISTRIBUTION (ASTM D422) Sample Location Boring B-2 @ 0-5' Boring B-3@ 7'-12' Sieve Size Percent Passing Percent Passing #4 100 100 #8 100 100 #16 99 100 #30 92 92 #50 54 21 #100 32 10 #200 27 14 COLLAPSE POTENTIAL {ASTM D 5333) Sample Location Initial Moisture Content Initial Density Consolidation Before Water Added Consolidation After Water Added Final Moisture Boring B-1 @4½' 4.6 % 100.7 pcf 3.9% 8.8% 17.1 % SOLUBLE SULFATES {CALIFORNIA TEST 417) Sample Location Soluble Sulfate Boring B-2 @ 0-5' 0.006 % (SO4) Boring B-1@ 10½' 3.2 % 103.6 pcf 2.3 % 2.9% 18.7% CWE 2180441.01 September 21, 2018 Plate No. B-2 -... ... .. -... --... .. .. --.. ... ... .. -... .. -... ... .. ... ... ... -... ... ... .. -... ... ... -... Appendix C References ... -... .. ... -... ... -.. .. -.. .. -.. .. -.. ... -... ... ... ... ... -... ... .. --.. --... CWE 2180441.02 September 21, 2018 Appendix C-1 REFERENCES California Emergency Management Agency -California Geological Society-University of Southern California, 2009, Tsunami Inundation Map for Emergency Planning, Oceanside and San Luis Rey Quadrangles, scale 1:24,000, dated June 1, 2009 . Federal Emergency Management Agency, 2012, San Diego County, California and Incorporated Areas Flood Insurance Rate Map, Panel 06073C0764G . Historic Aerials, NETR Online, historicaerials.com Jennings, C.W. and Bryant, W. A., 2010, Fault Activity Map, California Geological Survey, Geologic Data Map No. 6, http:/ /www.quake.ca.gov/gmaps/FAM/faultactivitymap.html Kennedy, Michael P. and Tan, Siang S., 2007, Geologic Map of the Oceanside 30'x60' Quadrangle, California, California Geologic Survey, Map No. 2. Tan, S.S., 1995, Landslide Hazards in the Northern Part of the San Diego Metropolitan Area, San Diego County, California, California Division of Mines and Geology Open-File Report 95-04. U.S. Geological Survey, U.S. Seismic Design Maps Web Application, http://geohazards.usgs.gov/ designmaps/ us/ application. php U.S. Geological Survey, Quaternary Faults in Google Earth, http://earthquake.usgs.gov/hazards/ qfaults/ google. php - -... --... ... ... -... -.. ... .. .. -... -.... ----... .... .. -.. .. -... .. .. Appendix D Recommended Grading Specifications -General Provisions -.. -... - --.. .. -.. .. -.. ... -.. ----,,. .... -.... --.. .. -.. -.. .. .. - CWE 2180441.02 September 21, 2018 Appendix D, Page D-1 RECOMMENDED GRADING SPECIFICATIONS -GENERAL PROVISIONS GENERAL INTENT PROPOSED SELVIDGE RESIDENCE 5170 CARLSBAD A VENUE CARLSBAD, CALIFORNIA The intent of these specifications is to establish procedures for clearing, compacting natural ground, preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary geotechnical investigation report and/ or the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede the provisions contained hereinafter in the case of conflict. These specifications shall only be used in conjunction with the geotechnical report for which they are a part. No deviation from these specifications will be allowed, except where specified in the geotechnical report or in other written communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian Wheeler Engineering shall be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer or his representative provide adequate observation so that he may provide his opinion as to whether or not the work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geotechnical Engineer and to keep him appraised of work schedules, changes and new information and data so that he may provide these opinions. In the event that any unusual conditions not covered by the special provisions or preliminary geotechnical report are encountered during the grading operations, the Geotechnical Engineer shall be contacted for further recommendations . If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc., construction should be stopped until the conditions are remedied or corrected or he shall recommend rejection of this work . -.. ------- -.. -.. .. ... -- ... ... -.... ... ... ... ... ... - ,,,. .. ... ... -... - CWE 2180441.02 September 21, 2018 Appendix D, Page D-2 Tests used to determine the degree of compaction should be performed in accordance with the following American Society for Testing and Materials test methods: Maximum Density & Optimum Moisture Content -ASTM D1557 Density of Soil In-Place -ASTM D1556 or ASTM D2922 All densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM testing procedures. PREPARATION OF AREAS TO RECEIVE FILL All vegetation, brush and debris derived from clearing operations shall be removed, and legally disposed of. All areas disturbed by site grading should be left in a neat and finished appearance, free from unsightly debris. After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soil which possesses an in-situ density of at least 90 percent of its maximum dry density . When the slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to 1 vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent formational soil. The lower bench shall be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as specified herein for compacted natural ground. Ground slopes flatter than 20 percent shall be benched when considered necessary by the Geotechnical Engineer. Any abandoned buried structures encountered during grading operations must be totally removed . All underground utilities to be abandoned beneath any proposed structure should be removed from within 10 feet of the structure and properly capped off. The resulting depressions from the above -.. ------... --.. .. .. .. - -... -... ... -... --... ,.. .. .. -.. --- CWE 2180441.02 September 21, 2018 Appendix D, Page D-3 described procedure should be backfilled with acceptable soil that is compacted to the requirements of the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drains and water lines. Any buried structures or utilities not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recommendation will be necessary. All water wells which will be abandoned should be backfilled and capped in accordance to the requirements set forth by the Geotechnical Engineer. The top of the cap should be at least 4 feet below finish grade or 3 feet below the bottom of footing whichever is greater. The type of cap will depend on the diameter of the well and should be determined by the Geotechnical Engineer and/ or a qualified Structural Engineer . FILL MATERIAL Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized rocks and expansive or detrimental soils are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation, or soils with low strength characteristics may be thoroughly mixed with other soils to provide satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any import material shall be approved by the Geotechnical Engineer before being brought to the site . PLACING AND COMPACTION OF FILL Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compaction effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipment should either be specifically designed for soil compaction or of proven reliability. The minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminary geotechnical investigation report . -... ---... -- --... -.. ... .. -.. -... ... .. -.. ... .. ---.. .. .. -.. -.. -.. CWE 2180441.02 September 21, 2018 Appendix D, Page D-4 When the structural fill material includes rocks, no rocks will be allowed to nest and all voids must be carefully filled with soil such that the minimum degree of compaction recommended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in non- structural fills is discussed in the geotechnical report, when applicable. Field observation and compaction tests to estimate the degree of compaction of the fill will be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be at the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than the required degree of compaction, the layer shall be reworked to the satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment . Compaction by sheepsfoot roller shall be at vertical intervals of not greater than four feet. In addition, fill slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut-back to finish contours after the slope has been constructed. Slope compaction operations shall result in all fill material six or more inches inward from the finished face of the slope having a relative compaction of at least 90 percent of maximum dry density or the degree of compaction specified in the Special Provisions section of this specification . The compaction operation on the slopes shall be continued until the Geotechnical Engineer is of the opinion that the slopes will be surficially stable. Density tests in the slopes will be made by the Geotechnical Engineer during construction of the slopes to determine if the required compaction is being achieved. Where failing tests occur or other field problems arise, the Contractor will be notified that day of such conditions by written communication from the Geotechnical Engineer or his representative in the form of a daily field report. If the method of achieving the required slope compaction selected by the Contractor fails to produce the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction is obtained, at no cost to the Owner or Geotechnical Engineer. ------ -.. ... .. ... ... -... --- --.. -.. -... --... ---.. --.. CWE 2180441.02 September 21, 2018 Appendix D, Page D-5 CUT SLOPES The Engineering Geologist shall inspect cut slopes excavated in rock or lithified formational material during the grading operations at intervals determined at his discretion. If any conditions not anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shall be analyzed by the Engineering Geologist and Geotechnical Engineer to determine if mitigating measures are necessary . Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shall be made during the filling and compaction operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or his representative or the observation and testing shall release the Grading Contractor from his duty to compact all fill material to the specified degree of compaction . SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS -SPECIAL PROVISIONS RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natural ground, compacted fill, and compacted backfill shall be at least 90 percent. For street and -... .. .. .. .. .. .. --.. .. -.. .. .. -.. --------.. ... .. ------.. ... CWE 2180441.02 September 21, 2018 Appendix D, Page D-6 parking lot subgrade, the upper six inches should be compacted to at least 95 percent relative compaction . EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion index of 50 or greater when tested in accordance with the Uniform Building Code Standard 29-2 . OVERSIZED MATERIAL: Oversized fill material is generally defined herein as rocks or lumps of soil over 6 inches in diameter. Oversized materials should not be placed in fill unless recommendations of placement of such material are provided by the Geotechnical Engineer. At least 40 percent of the fill soils shall pass through a No. 4 U.S. Standard Sieve. TRANSITION LOTS: Where transitions between cut and fill occur within the proposed building pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as structural backfill. In certain cases that would be addressed in the geotechnical report, special footing reinforcement or a combination of special footing reinforcement and undercutting may be required.