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HomeMy WebLinkAbout; APNs 155-140-37 and 155-140-38; Prelim Geotech Evaluation; 2003-09-18APNs 155^140-37 AND 1S5-140-38 CItY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA p -"--P-}p^P ,:V;^FOR^^ P:: -'^-.Z^.p-ZZ MR: EDWARD H; HAGEY P.O. BOX 99961 SAN DIEGb, CALIFORNIA^ VV:0.3213-ArSC: SEPTEMBER 18, 2003 / y Geotechnicai • Geologic • Coastal • Environmental 5741 PalmerWay • Carlsbad, California92010 • (760)438-3155 • FAX (760) 931-0915 September 18,2003 W.O, 3213-A-SC Mr. Edward H. Hagey P.O. Box 99961 San Diego, Califomia 92169-3961 Subject: Updated Preliminary Geotechnical Evaluation, APNs 155-140r37 and 155-140-38, City of Carlsbad, San Dlego County, California Dear Mr. Hagey: In accordance with your request, GeoSoils, Inc. (GSI), has reviewed site conditions and the referenced report prepared by GSI (1993), with respectto the proposed development ofthe subject site. Unless specifically superceded in the text ofthis report, recommendations contained In that report (see Appendix A) are considered valid and applicable. The following comments and/or additional recommendations are based on our understanding of the proposed development, previous and additional field exploration, a review of site conditions and a review of the referenced documents. EXECUTIVE SUMMARY Based on our review ofthe available data (see Appendix A), as well as field exploration, laboratory testing, and geologic and engineering analysis, development of the property appears to be feasible from a geotechnical viewpoint, provided the recommendations presented In the text ofthis report are properly incorporated into design and construction ofthe project. The most significant elements ofthis study are summarized below: • All existing undocumented artificial fill, colluviumAopsoil, and near surface weathered terrace deposits are generally loose and potentially compressible, and are not suitable for the support of settlement sensitive improvements. These materials will require removal and recompaction if settlement sensitive improvements are proposed within their Influence, In general, removals will be on the order of ±2 to ±8 feet across a majority of the site, however, deeper removals cannot be precluded. Depth of removals are outlined in the conclusions and recommendations section ofthis report. • Regional groundwater and surface water are not anticipated to significantly affect site development, provided that the recommendations contained in this report are incorporated into final design and construction, and prudent surface and subsurface drainage practices. Including proper in-igation, are incorporated into the construction plans. Perched groundwater conditions along fill/bedrock contacts, and along zones of contrasting pemieabilities, may not be precluded from occumng in the future due to site inigation, poor drainage conditions, or damaged utilities, and shouid be anticipated. Should perched groundwater conditions develop, this office could assess tiie affected area{s) and provide tiie appropriate recommendations to mitigate the observed groundwater conditions. Our laboratory test results indicate the expansion potential of onsite soils is very low to low In accordance witii Standard No. 18-2 ofthe Uniform Building Code (UBC, International Conference of Business Officials [ICBO], 1997). It Is anticipated tiiat earthwori< performed onsite will generally result in very low to low expansive soil conditions. However, onsite soils exhibiting a medium expansive potential may not be precluded. The soluble sulfate content ofthe site soils have been tested to be moderate and site soils are classified as severely con'oslve toward ferrous metals. Thus, consultation witii a con-osion engineer should be recommended. On a preliminary basis, the use of Type ll, concrete is anticipated per Table 19-A-4 ofthe UBC (ICBO, 1997). Based on ttie available data, conventional foundations utilizing slabs-on-grade, and/or post-tensioned foundation systems may be used. Based on our review and evaluation, tiie site is expected to have a relatively low exposure to seismic risks O-e., liquefaction, surface rupture, etc.). The seisnriicity acceleration values provided herein should be considered during the design ofthe proposed development. Adverse geologic structures that would preclude site development were not observed. The geotechnical design parameters provided herein should be considered during project planning design and construction by the project stiuctural engineer and/or architects. Mr. Edward H. Hagey ~ W.0.^13-A_SC Re:e:\wp9\3a)0\3213a.pge "^^S^ GeoSoils, Inc. The opportunity to be of service is greatiy appreciated, if you have any questions Concerning tbte report, or if we may be of further assistance, piease do not hesitate to contact tiie project geologist, Bryan E. Voss, at (760) 438-3155. Respectfully submitted, GeoSoils, Inc. ^fyan E>voss Projecraeologist Reviewed by: John P. Franklin Engineering Geologist, BV/JPF/DWS/jk/jh Distribution: (4) Addressee Revie)pipd by; >kelly Qvll Engineer, RCE Mr. Edward E. Hagey Rle:eAwp7\3200\3213a4jge W.O. 3213-A-SC Page Three GeoSoils, Inc. TABLE OF CONTENTS SCOPE OF SERVICES SITE CONDITIONS/PROPOSED DEVELOPMENT 1 FIELD STUDIES - •• ^ REGIONAL GEOLOGY ^ EARTH MATERIALS ^ Undocumented Artificial Fill (Map Symbol - Afij) 4 Colluvlum/Topsoll (Not Mapped) 4 Older Alluvium (Map Symbol - Ooa) ^ Terrace Deposits (Map Symbol - Qt) 4 Santiago Formation (Map Symbol - Tsa) 5 GEOLOGIC STRUCTURE ^ FAULTING AND REGIONAL SEISMICITY .., 5 Regional Faults • ^ Seismicity ' Seismic Shaking Parameters ^ GROUNDWATER ^ LIQUEFACTION EVALUATION 9 SEISMIC HAZARDS 1° OTHER GEOLOGIC HAZARDS 10 LABORATORY TESTING Moisture-Density ^ ^ Laboratory Standard Shear Testing Expansion Potential ^2 Sulfate/Con-osion Testing ^2 PRELIMINARY EARTHWORK FACTORS 12 SLOPE STABIUTY 13 Gross Stability Analysis 1^ Surficial Slope Stability 13 GeoSoils, Inc. CONCLUSIONS AND RECOMMENDATIONS 13 General • General Grading ^ Demolition/Grubbing Treatment of Existing Ground i^ Fill Placement ' " " It Overexcavation/Transitions '' PRELIMINARY FOUNDATION RECOMMENDATIONS 17 General Preliminary Foundation Design Bearing Value • * ' Lateral Pressure l^ Footing Setbacks 1^ Construction • • • Expansion Classification - Very Low to Low (E.l. 0 to 50) 19 Expansion Classification - Medium (E.l. 51 to 90) 20 POST-TENSIONED SLAB SYSTEMS 21 Post-Tensioning Institute Method 22 WALL DESIGN PARAMETERS 23 Conventional Retaining Walls 23 Restrained Walls 23 Cantilevered Walls 24 Retaining Wall Backfill and Drainage 24 Wall/Retaining Wall Footing Transitions 28 TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS 28 Expansive Soils and Slope Creep 28 Top of Slope Walls/Fences 29 DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS 30 DEVELOPMENT CRITERIA 32 Slope Deformation 32 Slope Maintenance and Planting 32 Drainage • 33 Erosion Control 33 Landscape Maintenance 33 Gutters and Downspouts 34 Subsurface and Surface Water 34 Site Improvements 34 Tile Flooring 35 Additional Grading - - • 35 Mr. Edward E. Hagey '^^'"^ °^ ^"p^fSl Fiie:e:\wp9\3200\3213a.pge ^ GeoSoils, Inc. Footing Trench Excavation 35 Trenching "5 Utility Trench Backfill '^'^ SUMMARY OF RECOMMENDATIONS REGARDINGGEOTECHNiCALOBSERVATION AND TESTING •. 36 OTHER DESIGN PROFESSIONALS/CONSULTANTS 37 PLAN REVIEW 37 LIMITATIONS 37 FIGURES: Rgure 1 - Site Location Map , Figure 2 - California Fault Map ^ Detain Detail 2 Details 26 ATTACHMENTS: Plate 1 - Geotechnical Map of Text Plate 2 - Cross Section A-A' Rear of Text Plate 3 - Cross Section B-B' Rear of Text Appendix A - References • • R®ar of Text Appendix B - Explorations Rear of Text Appendix C - EQFAULT, EQSEARCH, AND FRISKSP Rear of Text Appendix D - Laboratory Data Rear of Text Appendix E - Slope Stability Analysis Rear of Text Appendix F - General Earthworic and Grading Guidelines Rear of Text Mr. Edward E. Hagey " Table of Contents nie:e:\wp9\3200\3213a.pge "^^S®"' GeoSoils, Inc. UPDATED GEOTECHNICAL EVALUATION APNs 155-140-37AND 155-140-38 C/TY OF CARLSBAD, SAN DIEGO COUNTY, CAUFORNIA SCOPE OF SERVICES The scope of our services has included the following: 1. Review of the referenced geotechnical report (GSI, 1993), available published geologic literature, and private consultants reports in the region (see Appendix A). 2. Geologic field reconnaissance mapping and ttie excavation of five hand auger borings to verify subsurface data presented in (GSI, 1993), to obtain samples of representative materials, and delineate soil and geologic parameters tiiat may affect the proposed development (see Appendix B). 3. General areal seismicity (see Appendix C). 4. Laboratory testing of representative soil samples collected during our subsurface exploration program (see Appendix D). 4. General liquefaction evaluation. 5. . Slope Stability Analysis (see Appendix E). 5. Appropriate engineering and geologic analysis of data collected and preparation of this report. SITE CONDITIONS/PROPOSED DEVELOPMENT The property is a roughly rectangular shaped lot bounded by Jefferson Street on the east, an adjacent residential property to the south, and a condominium complex to the north. Buena Vista Lagoon Is located along the western edge ofthe property (see Figure 1). The property itself consists of a relatively level pad area adjacent to Jefferson Street and a large natural slope, which descends approximately 50 to 55 feet westward from the pad area to Buena Vista Lagoon. Between the pad elevation of approximately 65 feet Mean Sea Level (MSL) and an elevation of approximately 25 feet MSL, the slope descends at an approximate gradient of 2y2:1 (horizontal: vertical). From an elevation of 25 feet MSL to the lagoon level, ttie slope flattens to a gradient of approximately 4^/2:1 (h:v). Several small, 3 to 5 feet wide, hand cut (?) ten-aces are present in the upper portion ofthe slope. Existing improvements to the property consist of remnants of an old foundation system (retaining walls and concrete slab) located in the northern portion ofthe existing pad area. GeoSoils, Inc. 3-r> T.poQnadi Copyright 81999 DeLornw YamwuBi. ME 0*096 SoufttDafai: USGS Base Map.'' San Luis Rey Quadrangle, Caiifornla-rSan Diego Co., 7.5 Minute Series (Topograpitic), 1968, by USGS, r=2000' 1/2 Scale Miles Raproducad with permUsion orantftd by Thomss Bros. Maps. TMa map ia copyrlghtad by Thomas Bros. Maps, it la unlawful to oopy or foproduoa alt or any pact theraof, whatnar for psraonal uaa or resale, without permission. All rights reserved. W.O. 3213-A-SC SITE LOCATION MAP Figure 1 Vegetation on the property in ttie vicinity of tiie pad area consists of some small trees and scattered grasses. Vegetation on ttie slope consists of primarily grasses. Drainage within the property Is predominately by sheet flow directed toward Jefferson Sti-eet or down the slope face toward Buena Vista Lagoon. it is our under^ding ttiat ttie existing stmctures will be demolished. The proposed site development will consist of preparing the pad for constnjction of a new residential stmctijre Cut and fill grading techniques would be utilized to create design grades for the proposed single-family residential stucture. It is anticipated ttiat ttie residential development will consist of a one- and/or two-story structure wrth slab-on-grade and continuous footings, utilizing wood-frame construction. Building loads are assumed to be typical for ttils type of relatively light construction. The need for import soils is unknown. It is anticipated that sewage disposal will be tied into the regional municipal system. FIELD STUDIES Field wori< conducted during our evaluation ofthe site consisted of excavating five hand auger borings within the lotto verify near surface soil and geologic conditions presented In GSI's previous report (GSI, 1993). The borings were logged by a geologist from ourfirm. Representative bulk and In-place samples were taken for appropriate laboratory testing. Logs of the borings and previous explorations are presented in Appendix B, The approximate locations ofthe five borings and five previous exploratory borings (GSI, 1993), are shown on Plate 1. RFGIQNAL GEOLOGY The subject property is located wittiin a prominent natural geomorphic province in southwestem California known as the Peninsular Ranges. It Is characterized by steep, elongated mountain ranges and valleys that trend northwesteriy. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks. Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California batholrth. In the San Diego region, deposition occun-ed during tiie Cretaceous Period and Cenozoic Era In the continental margin of aforearc basin. Sediments, derived fi-om Cretaceous-age plutonic rocks and Jurassic-age volcanic rocks, were deposited into the narrow, steep, coastal plain and continental margin ofthe 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, tills plain was uplifted, eroded and incised. Alluvial deposits have since filled the lower valleys, and young marine sediments are currentiy being deposited/eroded within coastal and beach areas. Mr. Edward E. Hagey " 3213-A^C APNs 155-140-37 and 155-140-38 September 18.2003 Rle:e:\wpgS3a)0\3213a.pge '^^9® ^ GeoSoils, Inc. EARTH MATERIALS Earth materials encountered on the site consist of undocumented artificial fill, colluvium/lopsoil, older alluvium, tenace deposits, and Santiago Fomnation. The estimated limits of earth materials are shown on Plate 1. Undocumented Artificial PH (Map Svmbol - Afu) Undocumented artificial fill onsite was found to generally consist of a brown, damp to moist, loose silty sand. Thickness of the soil is approximately ±1 to ±8 feet (behind existing ±8 feet high retaining wall constiucted along the northwestern edge of tiie pad area). Minor fills are also presented along ttie outside edges of the pad. The existing fill at the subject site is considered potentially compressible in its present state, and considered unsuitable for support of additional fill and/or settlement sensitive improvements. These matenals will require removal and recompaction. should settlement sensitive improvements be proposed within tiieir influence. Colluvium/Topsoil fNot Mapped) Surficial colluviumAopsoil onsite was found to generally consist of a brown, dry. loose, silty sand with occasional rounded pebbles. Thickness of tiie soli is approximately ±1 to ±2 feet. ColluviumAopsoil at tiie subject site is considered potentially compressible in its present state. Accordingly, tiiese soils are considered unsuitable for support of additional fill and/or settlement sensitive Improvements in their existing state and will require removal and recompaction, should settlement sensitive improvements be proposed within their influence. Older Alluvium (Mao Symbol - Qoa) Older alluvium was encountered below an approximate elevation of 35 to 40 feet MSL on the descending slope. Where encountered, the older alluvium generally consist of reddish brown, damp to moist, silty sand, and is kDose to medium dense with depth. Due to the relatively soft and weatiiered condition of ttie upper ±2 feet, tiiese sediments should be removed, moisture conditioned, and recompacted and/or processed in place, should settlement-sensitive Improvements be proposed within their influence. At tiie time ofthis report, these materials are located beyond the anticipated limits of proposed consti-uction and are not anticipated to affect site development. Terrace Deposits (Map Symbol - Qt) Underiying the colluvium/topsoil, Quatemary-age terrace deposits were encountered to a depth of approximately 16 feet below existing grade in Boring B-1 (GSI, 1993) and in the slope face with hand auger B-1 and B-2 during this current study. As encountered, the terrace deposits generally consist of reddish brown, damp to moist, silty sand, and are Mr. Edward E, Hagey - ^fbeflTpS^ APNs 155-140-37 and 155-140-38 ^^.^ Rle:e:\wp9\3200\3213a.pge ^ GeoSoils, Inc. medium dense to dense witti depth. Due to ttie relatively soft and weathered condition of tiie upper ±1 foot, ttiese sediments shouid be removed, moishjre conditioned, and recompacted and/or processed In place. shouW settlerrient-sensitive improvements be proposed wittiin ttieir influence. This unit typically has a very low to low expansion potential. Santiago Formation (Map Svmbol - Tsa) Bedrock materials underiie ttie project site at deptti, and have been mapped by Tan and Kennedy (1996) as belonging to ttie Eocene-age Santiago Fomiation. As encountered, the formational materials generally consist of a highly oxidized, reddish brown to light brown, damp to moist, fine to medium-grained clayey sandstone to silty sandstone, and is medium dense/mediumstifftodense/stiffwittideptti. Thisunittypicallyhasavery low to medium expansion potential, depending on the clay content of ttie mati-ix materials. fiPOLOGiC STRUCTURE Neariy horizontal contacts were obsen/ed in our exploratory boring between terrace deposits and the underlying Santiago Fonmation. Clayey interbeds wrthin the Santiago Formation also displayed relatively horizontal contacts wittiin tiie bounding sandstone units (GSI 1993). Regional mapping by Tan and Kennedy (1996) indicates approximately horizontal to very gently dipping bedding shuctijres. Based on the available, adverse geologic stmctures are generally not anticipated to adversely affect the proposed development. FAULTING AND REGIONAL SEISMICITY Regional Faults Our review Indicates that there are no known active faults crossing this site within the area proposed for development, and ttie site Is not wrthin an Earthquake Faurt Zone (Hart and Bryant, 1997). However, the site is sftuated in an area of active, as well as potentially-active, faurtlng. These include, but are not limited to: tiie San Andreas faurt; the San Jacinto faurt; the Elsinore fautt; ttie Coronado Bank faurt zone; and the Newport-Inglewood - Rose Canyon faurt zone. The location of these, and ottier major faults relative to the srte, are indicated on Rgure 2 (California Faurt Map). The possibility of ground acceleration or shaking at tiie srte may be considered as approximately similar to the southem Califomia region as a whole. Major active faurt zones ttiat may have a significant affect on the srte. should they experience activrty, are listed in the following table (modrtied fi-om Blake, 2000a): Mr. Edward E. Hagey c^Jmi;.^!^^^ APNs 155-140-37 and 155-140-38 September 18,2003 FBe:e:\wp9\3200\3213a.pge GeoSoils, Inc. CALIFORNIA FAULT MAP Hagey Residence 1100 1000-- 900-- 800 -- 700 -- 600 500 -100 400-- 300 -- 200 100 -400 -300 -200 -100 0 W.O. 3213-A-SC 100 200 300 400 500 600 Figure 2 •iiiiiifiSMiiMti^^ Newport-Inglewood (Offshore) 5.1 (8.2) Rose Canyon 5.5 (8.8) Coronado Banks 21.4 (34.4) Elsinore-Temecula 23.8 (38.3) Elsfnore-Julian 24.2 (38.9) Elsinore-Glen Ivy 32.7 (52.6) Palos Verdes 35.0 (56.4) Earthquake Valley 44.4 (71.5) Newport - Inglwood (LA. Basin) 44.9 (72.3) San Jacinto - Anza 46.3 (74.5) San Jacinto - San Jacinto Valley 46.7 (75.1) 1 Chino - Central Ave. (Elsinore) 46.7 (75.1)) 1 Whittier 50.1 (80.7) Seismicity The acceleration-attenuation relations of Idriss (1994), and Campbell (1997) Horizontal-Random have been incorporated Into EQFAULT (Blake. 2000a), For this study, peak horizontal ground accelerations anticipated at ttie site were determined based on the random mean plus 1 sigma attenuation curve and mean attenuation curve deve oped by Joyner and Boore (1982a and 1982b). Sadigh etal. (1987). and Bozorgnia et al. (1999). EQFAULT is a computer program by Thomas F. Blake (2000a). which performs deterministic seismic hazard analyses using up to 150 digitized California faurts as earthquake sources. The program estimates ttie closest distance between each faurt and a given srte. ff a fault is found to be wrthin a user-selected radius, the program estimates peak honzontai ground acceleration ttiat may occur at the srte ft-om an upper bound ("maximum credible ) earthquake on that faurt, Srte acceleration (g) is computed by of fl. 30 user-selected acceleration-attenuation relations ttiat are contained in EQFAULT. Based on the EQFAULT program, peak horizontal ground accelerations from an upper bound event at ttie site may be on the order of 0.38g to 0.65g. The computer printouts of portions of the EQFAULT program are included within Appendix C. Mr. Edward E. Hagey APNs 155-140^7 and 155-140-38 Rle:e:\wp9\3a)0\3213a.pge W.O. 3213-A-SG September 18,2003 Page 7 GeoSoils, Inc. Historical srte seismicity was evaluated wrth the acceleration-attenuation relations of Campbell (1997) and the computer program EQSEARCH (Blake, 2000b). This program was utilized to perfonn a search of historical earthquake records for magnrtude 5.0 to 9 0 seismic events within a lOOHnile radius, between the years 1800 to 2001. Based on tiie selected acceleration-attenuation relation, a peak horizontal ground acceleration has been estimated, which may have affected the srte during the specific seismic events in ttie past Based on ttie avaiiabie data and attenuation relationship used, the estimated maximum (peak) srte acceleration during the period 1800 to 2002 was 0.46g. in addition, a seismic recurrence curve is also estimated/generated fi-om the histoncal data (see Appendix C). A probabilistic seismic hazards analyses was perfonned using FRISKSP (Blake, 2000c). which models earthquake sources as 3-D planes and evaluates the site specific probabiirties of exceedance for given peak acceleration levels or pseudo-relative velocity levels Based on a review of ttiese data, and considering the relative seismic activity ofthe southem Califomia region, a peak horizontal ground acceleration of p.30g was calculated. This value was chosen as rt corresponds to a 10 percent probabllrty of exceedance in 50 years (or a 475-year retum period). Computer printouts of the FRISKSP program are included in Appendix C. Seismic Shalcind Parameters Based on tiie site condrtions. Chapter 16 of ttie Uniform Building Code (UBC. Intemational Conference of Building Officials [ICBO]. 1997) seismic parameters are provided in the following table: litiMHSMItj--i»ARAMETERSf;;:!«!:^i:^ Seismic Zone (per Figure 16-2*) 4 Seismic Zone Factor (per Table 16-1*) 0.40 Soil Profile Type (per Table 16-J*) So Seismic Coefficient 0, (per Table 16:Q*) 0.44N, Seismic Coefficient 0, (per Table 16-R*) 0.64N, Near Source Factor (per Table 16-S*) 1.0 Near Source Factor (per Table 16-T*) 1.05 Distance to Seismic Source 5.1 mi (8.2 km) 1 Seismic Source Type (per Table 16-U*) B 1 Upper Bound Earthquake (Rose Canyon fault) M„6.9 1 *Rqure and Table references from Chapter 16 of the UBC (ICBO. 1997) Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 File:e:\wp9\3200^ 3a.pge GeoSoils, Inc. W.O. 3213-A-SC September 18,2003 Page 8 GROUNDWATER Groundwater was not encountered wittiin ttie property during field work performed In preparation of this report. Subsurface regional water is not anticipated to adversely affect srte development, provided that ttie recommendations contained in this report are Incorporated into final design and constiuction. Pmdent surface and subsurface drainage practices should be incorporated into ttie consti-uction plans. These observations reflect site condrtions at ttie time of our investigation, and do not preclude ftJttjre changes in local groundwater condrtions ft-om excessive inigation. preciprtation. or that were not obvious, at the time of our investigation. Seeps, springs, or other indications of a high groundwater level were not detected on tiie subiect property during the time of our field investigation. However, seepage may occur locally (due to heavy preciprtation or Inigation) in areas where fillsoils overlie sirty or clayey soils. Such soils may be encountered In ttie earth unrts that exist onsite. Perched groundwater condrtions along fill/bedrock contacts and along zones of conti-asting penneabilrtles should not be precluded ft-om occurring in the future due to srte irngation. poor drainage conditions, or damaged utilrties and should be anticipated. Should perched groundwater condrtions develop, tills office could assess the affected area(s) and provide the appropriate recommendations to mitigate tiie obsen/ed groundwater condrtions. LIQUEFACTION EVALUATION Liquefaction describes a phenomenon In which cyclic stresses, produced by earthquake induced ground motion, create excess pore pressures In relatively cohesionless soils. These soils may thereby acquire a high degree of mobility, which can lead to lateral movement sliding, consolidation and settlement of loose sediments, sand bolls, and other damaging deformations. This phenomenon occurs only below tiie water table, but after liquefaction has developed, rt can propagate upward into over-lying, 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 amounts of cementation; 2) sediments must consist mainly of medium to fine grained relatively cohesionless sands; 3) ttie sediments must have low relative densrty- 4) ft-ee groundwater must be present In ttie sediment; and, 5) the srte must experience seismic event of a sufficient duration and large enough magnrtude to induce straining of soil particles. It should be noted thattiiroughout our srte observations and subsurface investigation, there was no evidence of upward-directed hydraulic force that was suddenly applied, and was of short duration, nor were there any features commonly caused by seismically induced Mr. Edward E. Hagey ""^ WX> 3213-A-^ APNs 155-140-37 and 155-140-38 September 18 a)03 Rle:e:\wp9\3200\3213a.pge ^ GeoSoils, Inc. liquefaction, such as dikes, sills, vented sediment, lateral spreads, or soft-sediment defonnation. These features would be expected ff ttie srte area had been subject to liquefaction in the past (Obemneier, 1996). inasmuch astiieftjture perfonnance ofthe site wfth respect to liquefaction should be similar to the past, excluding the effects of urbanization (irrigation), GSI concludes that ttie sfte generally has not been subject to liquefaction in the geologic past, regardless of the deptii of the localized water table. Since at least one or two of the five required concurrent condftions discussed above do not have the potential to affect the srte where rt is proposed to be developed at tills time, and evidence of paleoliquefaction featijres were not obsen/ed, our evaluation indicates that the potential for liquefaction and associated adverae effects wfthin tiie areas of the srte proposed development is low, even with a ftjture rise in groundwater levels. The srte condrtions will also be Improved by removal and recompaction of low density near-surface soils. SEISMIC HAZARDS The following list includes other seismic related hazards tiiat have been considered during our evaluation of ttie sfte. The hazards listed are considered negligible and/or completely mitigated as a resurt of sfte location, soil characteristics, and typical srte development procedures: • Dynamic Settlement Surface Faurt Rupture Ground Lurching or Shallow Ground Rupture It is important to keep in perspective tiiat In the event of a "maximum probable" or "maximum credible" (upper bound) earthquake occurring on any of the nearby majorfaurts. strong ground shaking would occur in the subject srte's general area. Potential damage to any structure(s) would likely be greatest from ttie vibrations and Impelling force caused by the inertia of a sft-ucture's mass than from ttiose induced by ttie hazards considered above. This potential would be no greater than that for other existing stmctures and Improvements in tiie Immediate vicintty. OTHER GEOLOGIC HAZARDS Mass wasting refers to the various processes by which earth materials are moved down slope in response to the force of gravrty. Examples of these processes include slope creep, surficial failures, and deep-seated landslides. Creep is the slowest fomn of mass wasting and generally involves the outer 5 to 10 feet of a slope surface. During heavy rains, such as ttiose in 1969,1978,1980.1983,1993. and 1998. creep-affected materials may become satijrated, resurting in a more rapid forni of downslope movement (i.e.. landslides and/or surficial failures). Examples of these types of slope instabilrty do not exist within the site. Mr. Edward E Hagey ~ TT^?^?!^ APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp9\3200^3213a.pge "^9® '° GeoSoils, Inc. LABORATORY TESTING Laboratory tests were perfonned on representative samples ofthe onsite earth materials in order to evaluate ttieir physical characteristics. The test procedures used and results obtained are presented below. Molsture-Densitv The field moisture content and dry unrt weight were determined for each undistijrbed sample of the soils encountered in ttie borings. The dry unft weight was detemiined in pounds per cubicloot (pcf). and thefield moishjre content was detennined as apercenfage of the dry weight. The results of ttiese tests are shown on ttie Boring Logs (see Appendix B). Laboratorv Standard The maximum dry densrty and optimum moisture content was determined forthe major soil type encountered in the borings. The laboratory standard used was ASTM D-1557. The molsture-densrty relationship obtained forthis soil is shown below: 11 110! IB II w HH 1 11 1 A'i 1 i Silty Sand, Orange Brown B-1 @ O-'S' 119,0 13,5 Shear Testing Shear testing was performed on a representative, undisturbed sample of srte soil in general accordance wrth ASTM Test Method D-3080. in a Direct Shear Machine ofthe strain control type. Shear test results are presented as Plate D-1 in Appendix D, and as follows: lliilil SI IBfgiilPJiiMII lliilil ^!#i6REES]ii (! i! r. i; liililg mmmm i 1 B-1 @ 2' 317 33 275 33 Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Flle:e:\wpe\3200\3213a.pge GeoSoils, Inc. W.O. 3213-A-SC September 18,2003 Page 11 Expansion PotenBai Expansion testing was perfonned on a representative sample of site soil in accordance witii UBC Standard 18-2. The results of expansion testing are presented in the following table: B--\(a>0-X .«?iltv Sand 1 <5 Verv Low 1 Sulfate/Corrosion Testing A typical sample of the srte material was analyzed for corrosion/acidity potential. The testing included determination of soluble sulfates, pH, and saturated resistivfty. Resufts indicate that site soils are slightly acidic (pH=6.5) wrth respect to acidity and are severely con-oslve to terrous metals. Severely con-osive soils are considered to be below 1,000 ohms-cm. Based upon ttie soluble sulfate results of 0.144 percent by weight in soil, ttie site soils have a severe con-osion potential to concrete (UBC range for severe suHate exposure is 0.10 to 0 20 percentage by weight soluble [SO4] In soil. On a preliminary basis, the use of Type 11 concrete is anticipated according to Table 19-A-4 of ttie UBC (ICBO, 1997). Altemative methods and additional comments may be obtained ft-om a qualrtied corrosion engineer. PRELIMINARY EARTHWORK FACTORS Preliminary earthwork factors (shrinkage and bulking) forthe subject property have been estimated based upon our field and laboratory testing, visual srte observations, and experience wrth similar projects, rt is apparent that shrinking would vary witti depth and wrth areal extent over the sfte based on previous srte use. Variables include vegetation, weed conti-ol, discing, and previous filling or exploring. However, all these factors are drtficurt to define In a three-dimensional fashion. Therefore, the information presented below represents average shrinkage/bulking values: Undocumented Artrticiai Rll 10-20% shrinkage Colluvium/Topsoil 10-20% shrinkage Quaternary Terrace Deposits 10-15% shrinkage Tertiary Santiago Formation 0-6% shrinkage An additional shrinkage factor item would include the removal of root systems of individual large plants or ti-ees. These plants and trees vary in size, but when pulled, they may generally resurt in a loss of Vz to 1 Yz cubic yards. This factor needs to be multiplied by ttie Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Fite:e:\wp9\3200\3213a.pge W.O. 3213-A-SC September 18.2003 Page 12 GeoSoils, Inc. number of signrticant plants, ti-ees, or tree roots present to detennine ttie net loss. The above facts indicate that earthwork balance for ttie srte would be drfficutt to define and flexiblltty In design is essential to achieve a balanced end product. SLOPE STABILITY Conventional siope stebllrty analyses were perfonned utilizing ttie PC version of ttie computer program GSTABL7 v.2. The program perfomns a two-dimensional limrt equilibrium analysis to compute the factor of safety for a layered slope using the simplified Bishop or Janbu metiiods. Representative geologic cross sections were prepared for analysis, utilizing field and laboratory data ft-om our referenced report and this report and the 25-scale design sttjdy, depicting maximum existing slopes, as Indicated on Cross Sections B-B' (see Plate 3). The results ofthe analyses are Included in Appendix E. Gross Stability Analvsis A calculated factor-of-safety greater than 1.5 or 1.1 has been obtained for the existing, maximum height of the natural slope, when analyzed ft-om a static or seismic viewpoint, respectively. The results ofthe analyses are Included in Appendix E. Surficial Slope Stability The surficial stability ofthe proposed slopes have been analyzed. Our evaluation generally indicates a surficial safety factor greater than 1.5 for tiie existing slope. CONCLUSIONS AND RECOMMENDATIONS General Based on our field exploration to date. laboratory testing, and geotechnical engineering evaluations, rt is our opinion ttiat the srte appears feasible forthe proposed development ft-om a geotechnical engineering and geologic viewpoint, provided that the recommendations presented in the following sections are Incorporated into the design and construction phases of srte development. The primary geotechnical concems witti respect to the proposed development are: Depth to competent bearing sft-ata. Expansion and con-osion potential of srte soils. Potential for perched groundwater. Slope stability. Regional seismic activity. Mr. Edward E. Hagey ' ^ T ^K^^V'trS APNs 155-140-37 and 155-140-38 September 18. ZOOS Rle:e:\wp9\3200\3213a.pge '^^9® GeoSoils, Inc. The recommendations presented herein consider tiiese, as well as other aspects ofthe sfte. The engineering analyses peribmned conceming sfte preparation and tiie recommendations presented herein, have been completed using ttie information provided and obtained during our field work. In the event that any signrticant changes are made to proposed srte development, the conclusions and recommendations contained In tills report shall not be considered valid unless the changes are reviewed, and ttie recommendations of tills report verrtied or modified in wrrting by ttils office. Foundation design parameters are considered preliminary until ttie foundation design, layout, and stiuctural loads are provided to this officefor review. 1. Soil engineering, observation, and testing services should be provided during grading to aid the conti-actor in removing unsultablesoils and in his effort to compact the fill. 2. Geologic obsen/ations should be performed during grading to verify and/or ftJrther evaluate geologic condrtions. Arthough unlikely, if adverse geologic stmctures are encountered, supplemental recommendations and earthwork may be warranted. 3. The undocumented artificial fill and weatiiered near-surface tenrace depostts, are typically porous, loose, and subject to settlement. In the near surface, they are considered potentially compressible in their existing state, and have a very low to moderate potential for hydrocoUapse; thus, undocumented artificial fill and weathered near-surface terrace deposits may settle appreciably under additional fill, foundation, or Improvement loadings and will require removal and recompaction (and/or processing In-place) rt settlement-sensrtive improvements are proposed within their influence. In general, removals will be on the order of ±2 to ±3 feet across the majority of the srte. Removals will be on the order of ±2 to ±8 feet behind the existing ±8-foot high retaining wall, constructed along the northwest edge ofthe pad area; however, locally deeper removals may be necessary. 4. GSl performed a liquefaction screening evaluation of existing condrtions using tiie available data, ft is our opinion that the area site proposed for development at this time, is generally underiain by dense/stiff formational sediments, which have every low potential for liquefaction. 5. Groundwater is generally not anticipated to affect srte development, providing that the recommendations contained in tills report are incorporated into final design and construction, and that pmdent surface and subsurface drainage practices are incorporated into the consti-uction plans. Perched groundwater condrtions along zones of contrasting permeabilrties should not be precluded ft-om occurring in the ftrture due to srte irrigation, poor drainage conditions, or damaged utilrties, and should be anticipated. Should perched groundwater condrtions develop, this oflice could assess the affected area(s) and provide the appropriate recommendations to mrtlgate the obsen/ed groundwater conditions. Mr. Edward E. Hagey ' W.O 3213-A-SC APNs 155-140-37 and 155-14(^38 September 18.2003 Rle:e:\wp9\3200\3213a.pge P^S® GeoSoils, Inc. 6. Our laboratory test resulte and experience on nearby srtes related to expansion potential, indicate that soils wrth very low to low to potentially medium expansion indices underiie tiie srte. This should be considered during project design. Foundation design and consti-uction recommendations are provided herein for medium and high expansion potential classifications. 7. The soluble sutfate content of ttie srte soils have been tested to be moderate and site soils are dassHled as severely corrosive toward fen-ous metals. Thus, consultation wrth a con-osion engineer should be considered. On a preliminary basis, tiie use of Type ii concrete is anticipated according to Table 19-A-4 of tiie UBC (ICBO. 1997). 8. The seismicity-acceleration values provided herein should be considered during tiie design of the proposed development. 8. General Earthworic and Grading Guidelines are provided at the end ofthis report as Appendix F. Specrtic recommendations are provided below. General Grading All grading should confonn to ttie guidelines presented in the UBC (ICBO. 1997). the Crty and/or County, and Appendix F (tills report), except where specrtically superceded in the text ofthis report. When code references are not equivalent, the more stiingent code should be followed. During earthwori< constiuction, all srte preparation and the general grading procedures of tiie contractor should be observed and tiie fill selectively tested by a representative of GSI. rt unusual or unexpected condrtions are exposed in the field, they should be reviewed by this oflice and. rt warranted, modified and/or addrtional 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 tiie Constmction Safety Act should be met. Demolition/Grubbing 1. Existing structures, vegetation, and any miscellaneous debris should be removed fi-om the areas of proposed grading. 2. Any previous foundations, irrigation lines, cesspools, septic tanks, leach fields, or other subsurface structures uncovered during the recommended removal should be observed by GSI so that appropriate remedial recommendations can be provided. 3. Cavrties or loose soils remaining after demolition and srte clearance should be cleaned out and observed by ttie soil engineer. The cavrties should be replaced wrth fill materials tiiat have been moistijre condrtioned to at least optimum moisture content and compacted to at least 90 percent ofthe laboratory standard. Mr. Edward E. Hagey ~~ W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp9\3200\3213a.pge ^^9® '° GeoSoils, Inc. Treatment of Existing Ground 1. All undocumented artrticiai fill and weathered near-surface terace deposits should be removed to suitable ten-ace deposits and/or bedrock (i.e. Santiago Formation), cleaned of deleterious materials, as necessary, moishjrized, and recompacted if not removed by proposed excavation wrthin areas proposed for settlement-sensitive improvements. Variations firom these thicknesses should be anticipated. At this time, removal deptiis on the order of ±2 to ±3 feet across the majorrty of ttie srte. Removals will be on ttie order of ±2 to ±8 feet behind the existing ±8-foot high retaining wall constmcted along the northwest edge of tiie pad area should be anticipated; however, locally deeper removals may be necessary. 2. Subsequent to the above removals, the upper 12 inches of the exposed subsoils/bedrock should be scarified, broughtto at least optimum moistijre content, and recompacted to a minimum relative compaction of 90 percent of tiie laboratory standard. 3. Existing artrticiai fill, etc., and removed natural ground materials may be reused as compacted fill provided that major concentrations of vegetation and miscellaneous debris are removed priorto, or during, fill placement. 4. Localized deeper removal may be necessary due to buried utility trenches or dry porous materials. The project soils engineer/geologist should observe all removal areas during tiie grading. Fiil Placement 1. Subsequent to ground preparation, fill materials should be brought to at least optimum moisture content, placed in thin 6- to 8-inch IHte. and mechanically compacted to obtain a minimum relative compaction of 90 percent of the laboratory stendard. 2. Fill materials should be cleansed of major vegetation and debris prior to placement. 3. Any Import materials should be obsen/ed and determined surtable by tiie soils engineer firior to placement on the srte. Import material, rt any, for a fill cap should be low expansive (E.l. less than 50). Foundation designs may be artered rt import materials have a greater expansion value than tiie onsrte materials encountered in this investigation. 4. Any oversized rock materials greater than 8 Inches in diameter should be placed under the recommendations and supen/ision of the soils engineer and/or removed from the site. Per the UBC, such materials may not be placed wrthin 10 feet of finish grade. General recommendations for placement of oversize materials is contained in Appendix F (General Earthwork and Grading Guidelines). Afthough unlikely, Mr. Edward E. Hagey ' W.O 3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Fite:e:\wp9\3200i3213apge P^Qe 16 GeoSoils, Inc. should signrticant amounts of oversize rock be encountered, recommendations for rock fill placement should be adhered to. Overexcavation/Transitions In order to provide for tiie unrtonn support of tiie stiuctijres, a minimum 3-foot ttiick fill blanket Is recommended for lote containing earth material tiansrtions. P^y cut portion of tfie pad for ttie development should be overexcavated a minimum 3 feet below finish pad grade, to 5 feet horizontally, or a 1:1 (h:v) projection, down and away from settlement sensrtive Improvements. Areas wfth planned fills less than 3 feet should be overexcavated in order to provide the minimum fill tiiickness. Maximum to minimum fill ttiickness wrthin a given lot or pad should not exceed a ratio of 3:1 (max:min). PRELIMINARY 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 condttions of ttie proposed stmcture 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 tills office, tt is our understanding that slab-on-grade constmction is desired forthe proposed development. The information and recommendations presented in this section are not meant to supercede design by the project stiructural engineer. Upon request, GSI could provide additional input/consultation regarding soil parameters, as related to foundation design, Preliminarv Foundation Design Our review, field work, and laboratory testing indicates tiiat onsfte soils have a very low to lowto possible medium expansion potential. Preliminary recommendations for foundation design and constiuction are presented beiow. Final foundation recommendations should be provided at the conclusion of grading, and based on laboratory testing of fill materials exposed at finish grade. Bearing Value 1. The foundation systems should be designed and constiucted in accordance with guidelines presented in the latest edrtion ofthe UBC. 2. An allowable bearing value of 1,500 pounds per square foot (psi) may be used for the design of continuous footings at least 12 Inches wide and 12 inches deep, and column footings at least 24 inches square and 24 Inches deep. This value may be Mr. Edward E. Hagey ~ 75^^^^!^ APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp0\3a)O^13a.pge ''^S® GeoSoils, Inc. increased by 20 percent for each additional 12 inches In depth to a maximurn of 2,500 psf. No increase in bearing value is recommended for increased footing \A/ldth. Lateral Pressure 1. For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a concrete to soii contact when multiplied by the dead load. 2. Passive earth pressure may be computed as an equivalent fluid having a densrty of 250 pounds per cubic foot {pcf) wrth a maximum earth pressure of 2,500 psf. 3. When combining passive pressure and frictional resistance, tiie passive pressure component should be reduced by one-third. Footing Setbacks All footings should maintain a minimum 7-foot horizontal setback from the base of tiie footing to any descending slope. This distance Is measured from tiie footing face at the bearing elevation. Footings should maintain a minimum horizontal sett)ack of H/3 (H = slope height) from the base ofthe footing to the descending slope face and no less ttian 7 feet, nor need to be greater than 40 feet. Footings adjacent to unlined drainage swales should be deepened to a minimum of 6 inches below tiie invert of the adjacent unlined swale. Footings for stiuctures adjacent to retaining walls should be deepened so as to extend below a 1:1 projection from the heel of tiie wall. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances as described in tiie retaining wall section of tills report. Construction The following foundation constmction recommendations are presented as a minimum criteria from a soils engineering viewpoint. The onsite soils expansion potentials are generally in the very low to low range (E.l. 0 to 50). Expansive soil in the medium range (E.l. 51 to 90) may also be present onsrte. Accordingly, tiie Iollowing foundation construction recommendations asisume thatthe soils in the top 3 feet from finish grade will have a very low to possible medium expansion potential. Recommendations bythe project's design-struchjrai engineer or architect, which may exceed the soils engineer's recommendations, should take precedence over tiie following minimum requirements. Final foundation design will be provided based on tire expansion potential of the near surface soils encountered during grading. Mr. Edward E. Hagey ~~ ^ I^Rl^^.^o ^fi APNs 155-140-37 and 155-140-38 September 18,2003 R!e:e:\wp9\3200^13a.pge "^9®''° GeoSoils, Inc. Expansion Classification - Very Low to Low (E.1.0 to 50) 1. Conventional continuous footings should be ft)Unded at a minimum deptii of 12 inches below the lowest adjacent ground surface for one-story floor loads and 18 inches belowttie lowest adjacent ground surface for two-story floor loads. Interior fr)otings may be fiDunded at a deptti of 12 inches below the lowest adjacent ground surface. Footings for one-story floor loads should have a minimum widtti of 12 inches, and footings for two-story floor loads should have a minimum Width of 15 Inches. All footings should have one No. 4 reinforcing bar placed at tiie top and one No. 4 relnft)rclng bar placed attiie bottom of tiie footing. Isolated interior or exterior piers and columns shouid be ftjunded at a minimum deptti of 24 inches below tiie lowest adjacent ground suriace. 2. A grade beam, reinforced as above and at least 12 Inches square, should be provided across the garage enti^ces. The base of ttie reinforced grade beam should be at the same elevation as the adjoining footings. 3 Concrete slabs in residential and garage areas should be underiain wrth a vapor barrier consisting of aminimum of 10-mil, polyvinyl-chloride membrane wrth all laps sealed. This membrane should be covered with 2 inches of sand to aid in uniform curing of the concrete and mitigate puncturing of the vapor barrier. 4. Concrete slabs. Including garage slabs, should be a minimum of 4 Inches ttiick, and minimally reinforced wrth No. 3 reinforcement bars placed on 18-inch centers, in two horizontally perpendicular directions (i.e.. long axis and short axis). All slab reinforcement should be supported to ensure proper mid-slab height posrtioning during placement ofthe concrete. "Hooking" of reinforcement is not an acceptable metfiod of posrtioning. 5. Garage slabs should be poured separately from the residence footings and be quartered witii expansion joints or saw cuts. A positive separation from tfie footings should be maintained wrth expansion joint material to permft relative movement. 6. TTie residential and garage slabs should have an actual, minimum thickness of 4 inches, and the slab subgrade should be free of loose and uncompacted material prior to placing concrete. 7. Presaturation Is not necessary for these soii condrtions; however, the moisture content of the subgrade soils should be equal to or greater than optimum moisture to a depth of 12 inches below tfie adjacent ground grade in the slab areas, and verified by ttils office wrthin 72 hours of the vapor barrier placement. Mr. Edward E. Hagey q^mb.Ml15^ APNs 155-140-37 and 155-140-38 September 18, 20^ File:e:\wp9\3200\3213a.pge '^^9619 GeoSoils, Inc. 8. As an arternative, an engineered post-tension foundation system may be used. 9 Soils generated from footing excavations to be used onsfte should be compacted to a minimum relative compaction 90 percent of ttie laboratory standard, whettier ft is to be placed inside tiie foundation perimeter or in tiie yard/right-of-way areas. This material must not atter posrtive drainage pattemstiiat direct drainage away from tiie structural areas and toward the sti-eet. 10 Foundations near the top of slope should be deepened to confonn to the latest edftion ofthe UBC (ICBO, 1997) and provide a minimum of 7 feet horizontal distance from the siope face. Rigid block wail designs located along the top of slope should be reviewed by a soiis engineer. Expansion Classification - Medium (E-I. 51 to 90) 1. Conventional continuous footings should be founded at a minimum depth of 18 Inches belowtiie lowest adjacent ground surfaceforone-ortwo-story floor loads. Interior footings may be founded at a deptii of 12 inches below the lowest adjacent ground surface. Footings for one-story floor loads should have a minimum width of 12 inches, and footings for two-story floor loads should have a minimum width of 15 Inches. All footings shouid be reinforced wrth a minimum of two No. 4 reinforcing bars attiie top and two No. 4 reinforcing bare at the bottom. Isolated interior and/or exterior piers and columns are not recommended. 2. A grade beam, reinforced as above and at least 12 inches square, should be provided across tiie garage entrances. The base ofthe reinforced grade beam should be at the same elevation as tiie adjoining footings. 3. Concrete slabs in residential and garage areas should be underiain by a vapor ban-ier consisting of a minimum of 10-mil; polyvinyl-chloride membrane wrth ali laps sealed. Two inches of ttie sand base should be placed over and under the membrane (total of 4 inches) to aid in unifomn curing of the concrete and mitigate puncturing of tiie vapor ban-ier. 4. Concrete slabs. Including garage areas, should beaminimum of 4 inches thick, and minimally reinforced wfth No. 3 reinforcement bars placed on 18-inch centers, in two tiorizontally perpendicular directions (i.e., long axis and short axis). All slab reinforcement should be supported to ensure proper mid-slab height posrtioning during placement of ttie concrete. "Hooking" of reinforcement is not an acceptable method of posrtioning. Mr. Edward E. Hagey ~ ^V^'.^^'^^ APNs 155-140-37 and 155-140-38 September 18. 20^ Rle:e:\wp0\32OO^213a.pge Page 20 GeoSoils, Inc. 5. Garage slabs should be poured separately from the residence footings and be quartered witii expansion jointe or saw cute. A posrtive separation from tiie footings should be maintained wrth expansion joint material to pemnrt relative movement. 6. The residential and garage slabs should have an actual minimum tiiickness of 4 inches, and the slab subgrade should be free of loose and uncompacted material prior to placing concrete. 7. Presattjration of slab areas is recommended far these soil condrtions. The moisture content of each slab area should be 120 percent, or greater, above optimum and verifled bythe soil engineer to a depth of 18 inches b>elow adjacent ground grade in the slab areas, wrthin 72 hours of the vapor banier placement. 8. As an artemative, an engineered post-tension foundation system may be used. 9. Soils generated from footing excavations to be used onsite should be compacted to a minimum relative compaction 90 percent ofthe laboratory standard, whether rt Is to be placed Inside tiie foundation perimeter or in tiie yard/right-of-way areas. This material must not alter posrtive drainage pattems that direct drainage away from the structural areas and toward the street. 10. Foundations near the top of slope should be deepened to conform to the latest edition ofthe UBC (ICBO, 1997) and provide a minimum of 7 feet horizontal distance from tiie slope face. Rigid block wall designs located along tiie top of slope should be reviewed by a soils engineer. POST-TENSIONED SLAB SYSTEMS Recommendations for utilizing post-tensioned slabs on the site Is based on our limited subsurface Investigation on the site. The recommendations presented below should be followed in addrtion to those contained In the previous sections, as appropriate. The information and recommendations presented below In this secflon are not meant to supercede design by a registered structural engineer or civil engineer familiar with post-tensioned slab design. Post-tehsioned slabs should be designed using sound engineering practice and be in accordance wrth local and/or national code requirements. Upon request, GSI can provide addrtional data/consurtation regarding soil parameters as related to post-tensioned slab design. From a soil expansion/shrinkage standpoint, a common confributing factor to distress of stmctures using post-tensioned slabs Is fluctuation of moisture in soils underlying the perimeter ofthe slab, compared to the center, causing a "dishing" or "arching" ofthe slabs. To mitigate this possibility, a combination of soli presaturation and constiuction of a perimeter cut-off wall should be employed. Mr. Edward E. Hagey W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp9\3200\3213a.pge Page 21 GeoSoils, Inc. Perimeter cut-off walls should be a 18 Inches deep for medium and/or high expansive soils. The cut-off walls may be integrated into the slab design or independent ofthe slab and should be a minimum of 6 inches tiiick. The vapor banier should be covered wrth a 2-inch layer of sand to aid in unrtonn curing of tiie concrete; and ft should t>e lapped adequately to provide a continuous water-proof barrier under the entire slab. For medium or highly expansive soils, an additional 2 inches of sand should be placed on grade (4 Inches total) Specrtic soli presaturation Is not required; however, the moisture content ofthe subgrade soils should be equal to. or greater than, the soils' optimum moisture content to a depth of 18 inches below grade, for medium, or high expansive soils. Post-Tensioning Institute Method Post-tensioned slabs should have sufficient stifftiess to resist excessive bending due to non-uniform swell and shrinkage of subgrade soils. The differential movement can occur at the comer, edge, or center of siab. The potential for drtferential uplttt can he evaluated using ttie UBC Section 1816 (ICBO, 1997), based on design specrtications of tiie Post-Tensioning Instrtute (PTI). The following table presents suggested minimum coefficiente to be used in the PTI design method. 1 Thomthwaite Moisture Index -20 inches/year | 1 Correction Factor for Irrigation 20 inches/year Depth to Constant Soil Suction 7 feet Constant soil Suction (pf) 3.6 Modulus of Subgrade Reaction (pd) 75 MolstoJre Velocity 0.7 inches/month 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 stmctures have posrtive drainage that Is maintained away from stmctures. Therefore, rt is Important tiiat Infonnation regarding drainage, site maintenance, settlements, and effects of expansive soils be passed on to future owniers. Based on the above parameters, tiie following values were obtained from figures or tables of the UBC Section 1816 (ICBO. 1997). The values may not be appropriate to account for possible differential settlement of the slab due to otiier factors. If a stfffer slab is desired, higher values of ym may be warranted. Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rle:e:\wp9\3200\3213a.pge W.O. 3213-A-SC September 18,2003 Page 22 GeoSoils, Inc. iSiiiSlill liiiMiil iiMiiiWiil' e„ center lift 5.0 feet s.ofset 5,5 feet e„ edge lift 2.5 feet 3.5 feet 4.0 feet yn, center lift 1.0 inch 1.7 inches 2.7 Indies V™ edge lift 0.3 inches plus 0.75 Inches 0.75 indies Deepened footings/edges around the slab perimeter must be used to minimize non-unrtbnn surtiace moisture migration (from an outeide source) beneath the siab. An edge depth of 12 Inches should be considered a minimum. The t)ottom of tiie deepened footing/edge should be designed to resist tension, using cable or reinforcement per the stiuctural engineer. Other applicabie recommendations presented under conventional foundation and the Calrtomia Foundation Slab Method should be adhered to during the design and constmction phase ofthe project. WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that erther very low expansive soils (Class 2 pemneable fitter material or Class 3 aggregate base) or native materials 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 speclatty walls (i.e., crib, earthslone, geogrid, etc.) can be provided upon request, and would be based on site specrtic conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male comers, 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 comera, the resfrained wall design should extend a minimum distance of twice ttie height of the wall (2H) laterally fl^m the corner. Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rle:e:\wp9\3200\3213a.pge W.O. 3213-A-SC September 18,2003 Page 23 GeoSoils, Inc. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 10 feet high. Design parameters for walls less than 3 feet in height may be superseded by Ctty and/or County standard design. Active earth pressure may be used for retaining wall design, provided ttie top ofthe wall is not resfrained from minor deflections. An equivalent fluid pressure approacli may be used to compute the horizontal pressure against the wall. Appropriate fluid untt weights are given below for specrtic slope gradients ofthe retained material. These do not include other superimposed loading condrtions due to traffic, stmctures, seismic events or adverse geologic condftions. When wali configurations are finalized, the appropriate loading condrtions for superimposed loads can be provided upon request. i iiannii Level* 2to1 38 55 45 60 * Level backHil behind a retaining wail is defined as compacted earth materials, properly drained, without a slope for a distance of 2H behind the wall, where H is the 1 height of the wall. Retaining Wall Backtiil and Drainage Positive drainage must be provided behind all retaining walls in the fomn of gravel wrapped In geofabric and outiets. 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 erther Class 2 permeable filter material or Vz-inch to y4-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 wail. This material should be continuous (i.e.. ftjll height) behind the wail, and rt should be consfructed in accordance wrth the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limrted access and confined areas, (panel) drainage behind the wall may be consfructed in accordance wrth Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an expansion index (E.I.) potential of greater than 90 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detaii 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rle:e:\wpS\3200\3213a.pge W.O. 3213-A-SC September 18,2003 Page 24 GeoSoils, Inc. DETAIL Provide surface drainage (T) Water proofing nenbrane <op"tlonaD Weephole Finished surface [3) Filter fabric Ai 3/4 or flatter (D WATER PROOFING MEMBRANE CoptlonaDi Liquid boot or approved equivalent. (D ROCK» 3/4 to 1-1/2' Cinches) rock (3) FILTER FABRIC ® PIPEi Mlrl^ 140N or approved equivalent place fabric flap behind core. 4' (Inches) dianeter perforated PVC. schedule 40 proved alternative with nlnlnun of IX gradient to proper outlet point. ® ^^™nl"mun E' (Inches) dianeter placed at 20' (feet) on centers along the wall, and 3' (Inches) above finished surface. TYPICAL RETAINING WALL BACKRLL AND DRAINAGE DETAIL DETAIL 1 Geoteclinical • Geologic • Environmental DETAIL N . T . S . Provide surface drainage (T) Water proofing tnenbrane (optional)) (^ Weephole Finished surface /4 or f later (T) WATER PROOFING MEMBRANE (optlonal)i Liquid boot or approved equivalent. (D ^'^'^^'Jli^^^i^jj^ii^ gQQQ j-draln 200 or equivalent for non-waterproofed walls. Miradrain 6200 or J-draln 200 or equivalent for water proofed walls. 13) FTI TFR FABRICi Mirafi 140N or. approved equivalent place fabric flap behind core. ® (Inches) diameter perforated PVC. schedule 40 or approved alternative with ninlnun of IX gradient to proper outlet point. ® ^^^jiiinLun 2' (Inches) dianeter placed at 20' (feet) on centers along the wall, and 3* (Inches) above finished surface. RETAINING WALL BACKFILL AND SUBDRAIN DETAIL GEOTEXTILE DRAIN DETAIL 2 Geotechnical • Geologic • Environmental DETAIL Provide surface drainage or flater (2) Clean sand ^ backfill ® WATER PROOFING MEMBRANE (optlonal)i Liquid boot or approved equivalent. (2) CLEAN SAND BACKFILU Must have sand equivalent value of 30 or greaterj can be densified by water Jetting. (3) FILTER FABRICI Mirafi HON or approved equivalent. ® ^°^^[ cubic foot per linear feet of pipe of 3/4 to 1-1/2' (Inches) rock ^ PIPEi 4' (inches) dianeter perforated PVC. schedule 40 or approved alternative with ninlnum of IX gradient to proper outlet point. © WEEPHDLEi Minimum 2' (Inches) diameter placed at 20' (feet) on centers along the wall, and 3' (Inches) above finished surface. RETAINING WALL AND SUBDRAIN DETAIL CLEAN SAND BACKFILL DETAIL 3 Geotechnicai • Geologic • Environmental Outiete should consist of a 4-lnch diameter solid PVC or ABS pipe spaced no greater than ±100 feet apart, with aminimum of two outiete, one on each end. The use of weep holes In walls higher ttian 2 feet should not be considered. The suriace of the backfill should be sealed by pavement or the top 18 inches compacted wfth native soii (E.l. :<90). Proper surface drainage should also be provided. For addttional mttigation, consideration shouid be given to applying a water-proof membrane to tiie back of ail retaining stmctures. The use of a wateretop should be considered for ali concrete and masonry joints. Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance witii the recommendations in ttiis report. Should wall footings fransition from cut to fill, the civil designer may specify erther: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H. from tiie 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 /360for a distance of 2H on erther side of tiie fransition may be accommodated. Expansion jointe should be sealed wtth a flexible, non-shrink grout. c) Embedthefootingsentirely Into native formational material (i.e., deepened footings). If transrtions from cut to fill transect tiie 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 tiie wall alignment. TQP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS Expansive Soils and Slope Creep Soils at the site may be expansive and therefore, become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially wtth seasonal changes In moisture content. Typically In soutiiem Calrtornia. during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surtace cracks. The extent and deptii of these shrinkage cracks depend on many factors such as the nature and expansivity of tiie soils, temperature and humldtty, 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 con-esponding loss in soil denstty and shear sfrengtii near tiie slope suriace. With tiie 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 Mr. Edward E. Hagey ~~ W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18.2003 Rle:e:\wp9\320(A3213a.pge ^^9© 28 GeoSoils, Inc. 10 feet, tills creep related soil movement will typically impact all rear yard flatwork and other secondary Improvemente tiiat are located wrthin about 15 feet from the top of slopes, such as swimming pools, concrete flatworic, etc., and in partlculartop of slope fences/walls. This Influence is normally In tiie form of detrimental settlement, and tilting of tiie proposed Improvements. The dessication/swelling and weep discussed above continues over ttie life of the Improvemente, and generally becomes progressively worse. Accordingly, the devetoper should provide ttils infonnation to any homeownere and homeowners association. Top of Slope Wails/Fences Due to ttie potential for slope creep for slopes higher than alx>ut 10 feet, some settlement and tilting of ttie walls/fence wrth ttie con-esponding disfresses, should be expected. To mrtlgate tiie tilting of top of slope wails/fences, we recommend that the walls/fences be constmcted on a combination of grade beam and caisson foundations. The grade beam should be at a minimum of 12 Indies 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 wrth a minimum embedment lengtii of 7 feet below the bottom of the grade beam. The sfrengtii of ttie concrete and grout should be evaluated by the sfructural engineer of record. The proper ASTM teste fertile concrete and mortar should be provided along with the slump quantrties. The concrete used should be appropriate to mitigate suKate corrosion, as wan-anted. The design of tiie grade beam and caissons should be in accordance wrth tiie recommendations ofthe project stiuctural engineer, and include the utilization of the following geotedinicai parameters: Creep Zone: Creep Load: Point of Fixity: Passive Resistance: 5-foot vertical zone below the slope face and projected upward parallel to the slope face. The creep load projected on the area ofthe grade beam should betaken asan equivalentfluld approach, having a density of 60 pcf. For the caisson, rt should be taken as a unrtorm 900 pounds per linear foot of caisson's deptti, located above the creep zone. Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive eartti 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 tiiat they meet or exceed the minimum requiremente stated above. To determine the total lateral resistance, the confribution of the creep prone zone above the point of fixrty, to passive resistance, should be disregarded. Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rfe:e:\wp9\3200V3213a.pge W.O. 3213-A-SC September 18.2003 Page 29 GeoSoils, Inc. Allowable Axial Capacity: Shaft capacity: 350 psf applied beiow tiie point of fixtty over the surface area of the shaft. Tip capacrty: 4,500 psf. DRIVEWAY. FLATWORK. AND OTHER IMPROVEMENTS The soil materials on stte may be expansive. The effects of expansive soils are cumulative, and typically occur over the irtetime of any improvements. On relatively level areas, when the soils are allowed to dry, tiie dessication and swelling process tends to cause heaving and distress to flatworic ahd other improvements. The resulting potential for distress to improvemente may be reduced, but nottotally eliminated. To tiiat end, rt Is recommended that the developer should notify any homeowners or homeowners association of tills long-tenn potential for disttess. To reduce tiie likelihood of distress, tiie following recommendations are presented for all exterior flatwori<: 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. The moisture content ofthe subgrade should be verrtied wrthin 72 hours prior to pouring concrete. 2. Concrete slabs should be cast over a relatively non-yielding surifeice, consisting of a 4-inch layer of cmshed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. The layer should wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to tiie surrounding eartti materials. 3. Exterior slabs should be a minimum of 4 Inches tiiick. Driveway slabs and approaches should addrtionally 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 confrol slab cracking due to concrete shrinkage or expansion. Two ways to mrtlgate 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 jointe to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightiy cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. The exterior slabs should be scored or saw cut. to % inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow slabs, control jointe should be provided at Intervds of every 6 feet. The slabs should be separated from the foundations and sidewalks witii expansion joint filler material. Mr. Edward E. Hagey ~ W.O 3213-A-SC APNs 155-140-37 and 155-140-38 September 18, 2003 Rle:e:\wp9\3200\3213a.pge P^9® GeoSoils, Inc. 5 No tiafflc should be allowed upon ttie newly poured concrete slabs until they have been properiy cured to witiiin 75 percent of design sfrengtii. 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 ttie house with thick expansion joint filler material. In areas directiy adjacent to a continuous source of moisture O.e., inigation, planters, etc.), all jointe should be addrtionally sealed wrth flexible mastic. 7. Planters and walls should not be tied to tiie house. 8. Overhang stiuctijres should be supported on tiie slabs, or sfructurally designed wtth continuous footings tied in at least- two directions. 9. Any masonry landscape walls tiiat are to be constiucted throughout tiie property should be grouted and articulated in segments no more than 20 feet long. These segmente should be keyed or doweled together, 10. Utiltties should be enclosed wtthin a closed utilldor (vault) or designed with flexible connections to accommodate drtferential settlement and expansive soil condrtions. 11. Posrtive 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, rt should be kept in mind that drainage reversals could occur, including post- consfruction settlement, tf relatively flat yard drainage gradients are not periodically maintained bythe homeowner or homeowners association. 12. Due to expansive soils, air condrtloning (A/C) units should be supported by slabs that are incorporated into the building foundation or constmcted 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 rt proper finishing and curing practices are not followed. Finishing and curing practices should be perfonned per the Portland Cement Association Guidelines, Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, con-osion potential of soils, and fertilizers used on site. Mr. Edward E. Hagey ~ ' W.0.321^A-SC APNs 155-140-37 and 155-140-38 September 18. 2003 Rle:e:\wpS\3200\3213a.pge "^^Q® GeoSoils, Inc. DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factora of safety for gross or surficial stabilrty and constmcted In general accordance wrth the design specrtications should be expected to undergo some drtferential vertical heave or settlement In combination wtth differential lateral movement in the out-of-slope direction, after grading. This post-consfruction movement occurs in two fonns: slope creep, and lateral fill extension (LFE). Slope creep Is caused by artemate wetting and drying ofthe fill soils which resutts in slow downslope movement. This type of movement is expected to occur throughout tiie life of tiie slope, and is anticipated to potentially affect improvemente or stiuctures (i.e., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet ftxjm the top-of-slope, depending on tiie siope height. This movement generally resufts in rotation and drtferential settlement of improvemente located wrthin the creep zone. LFE occure due to deep wetting from irrigation and rainfall on slopes comprised of expansive matertals. Arthough some movement shouid be expected, long-tenn movementfrom this source may be minimized, but not eliminated, by placing the fiil throughout the slope region, wet ofthe fill's optimum moisture content. It Is generally not practical to attempt to eliminate the effects of either slope creep or.i-FE. Surtable mttigative measures to reduce ttie potential of lateral deformation typically include: setback of improvemente from the slope faces (per ttie Uniform Building Code and/or Caiifomla Building Code), positive stiuctijral separations (i.e., joints) between improvemente, and stiffening and deepening of foundations. All of these measures are recommended for design of stmctures and Improvements. The ramrtications ofthe above conditions, and reconimendationsfor 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 eartti materials. Slope stability is significantly reduced by overly wet condrtions. Posrtive suriace drainage away from slopes should be maintained and only the amount of inigation necessary to sustain plant Irte should be provided for planted slopes. Over-watering should t>e avoided as rt can adversely affect srte Improvements, and cause perched groundwater condttions. Graded slopes constmcted 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 consfruction. 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 Itttle 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 tiie potential for perched water, staining, mold, etc., to develop. A rodent confrol program to prevent bun-owing should be Implemented. Irrigation Mr. Edward E. Hagey W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp9\3200\3213a.pge Page 32 GeoSoils, Inc. of natural (ungraded) slope areas Is generally not recommended. These recommendations regarding plant type. Inigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building consbuction activities and landscaping. Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse perfonnance of ftDundatlons, hardscape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near stiuctures and tops of slopes. Lx>t surface drainage shouid be careftjily taken Into consideration duringfine grading, landscaping, and buiiding consbuction. Tlierefore, care should be taken thatfuture landscaping or constmction activrties do not create adverse drainage condftions. Positive stte drainage wtthin lots and common areas should be provided and maintained at all times. Drainage should not fiow uncontrolled down any descending siope. Water should be directed away from foundations and not allowed to pond and/or seep Into the ground. In general, the area wrttiin 5 feet around a sfructure shouid slope away from the stmcture. We recommend that unpaved lawn and landscape areas have a minimum gradient of one percent sloping away from stmctures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding consbuction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area(s). Afthough not a geotechnical requirement, roof guttera. down spoute, or other appropriate means may be utilized to confrol roof drainage. Dovm spouts, or drainage devices should outlet a minimum of 5 feet from stmctures 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, tf 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, Onsfte eartti materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and sitt fences for the temporary confrol of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant Irte should be provided. Over-watering the landscape areas will adversely affect proposed site improvemente. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum distance of 10 feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom ofthe planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. rt planters are constructed adjacentto stmctures, the sides and bottom ofthe planter should be provided Mr. Edward E. Hagey W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18, 2003 RIe:e:\wp9\3a)0\3213a.pge Page 33 GeoSoils, Inc. wrth a moistijre barrier to prevent penetration of irrigation water into tiie subgrade. Provisions should be made to drain tha excess Irrigation water from the planters without saturating the subgrade below or adjacentto the plantei-s. Graded slope areas should be planted wrth drought resistant vegetation. Consideration should be given to tiie type of vegetation chosen and their potenti'ai effect upon surface improvemente (i.e., some frees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping, tf 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 guttera and downspouts should be considered to collect roof water tiiat may otherwise infittrate the soils adjacent to the stmctures. tf utilized, the downspoute should be drained Into PVC collector pipes or non-erosive devices that will carry the water away from the house. Downspoute and gutters are not a requirement; however, from a geotechnical viewpoint, provided that posrtive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affed srte development, provided that the recommendations contained in this report are Incorporated Into final design and consfruction and tiiat prudent surface and sufc)surface drainage practices are incorporated into the constmction plans. Perched groundwater condrtions along zones of confrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage condrtions, or damaged utilrties, and shouid be anticipated. Should perched groundwater condrtions develop, this office couid assess the affected area(s) and provide the appropriate recommendations to mrtigate the observed groundwater condrtions. Groundwater conditions may change wrth the infroduction of irrigation, rainfall, or other factors. Site Improvements Recommendations for exterior concrete flatwork design and construction can be provided upon request, tf in the future, any addttional improvements (e.g.. pools, spas, etc.) are planned for the sfte, recommendations concerning the geological or geotechnicai aspects of design and constmction of said improvemente could be provided upon request. This office should be notified in advance of any fill placement, grading of the srte, or trench backfilling after rough grading has been completed. This inciudes any grading, utilrty french, and retaining wall backfills. Mr. Edward E. Hagey W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18, 2003 R1e:e:\wp9\3200\3213a.pge Page 34 GeoSoils, Inc. Tile Flooring Tile flooring can crack, reflecting cracks in ttie concrete slab beiow ttie tile, arthough small cracks in a conventional slab may not be signrticant. Therefore, the designer should consider additional steei 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. Slipsheete or a vinyl crack isolation membrane (approved by the Tile Council of America/CeramicTiie Instftute) 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 tiie site, or french backfilling after rough grading has been completed. This Includes completion of grading in tfie sfreet and parking areas and utility french and retaining wail backfills. Footing Trench Excavation All footing excavations should be observed by a representative of tills firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to verify that tiie excavations are made into the recommended bearing material and to the minimum widths and depths recommended for constmction. tf loose or compressible materials are exposed wfthin the footing excavation, a deeper footing or removal and recompaction ofthe subgrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utiltty trench excavations should be compacted to a minimum relative compaction of 90 percent, tf not removed from tiie sfte. Trenching Considering the nature of tiie onsite soils, ft should be anticipated that caving or sloughing could be afactor in subsurface excavations and frenchlng. Shoring or excavating the french walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be obsen/ed by one of our representatives and minimally conform to CAL-OSHA and local safety codes. Utility Trench Backfill 1. All interior utilrty french 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. Observatton. probing and testing should be provided to vertfy the desired results. Mr. Edward E. Hagey W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp8\3200'i3213a.pge Page 35 GeoSoils, Inc. 2. Exterior frenches adjacent to, and wrthin areas extending below a 1:1 plane projected from the outeide bottom edge of tiie footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of tiie laboratory standard. Sand iDackfill, unless excavated from ttie tirench, should not be used in these backfill areas. Compaction testing and observations, along wtth probing, should be accomplished to verily the desired resufts. 3. Ail french excavations should confonn to CAL-OSHA and local safety codes. 4. Utilrties crossing grade beams, perimeter beams, or footings should etther pass beiow tiie footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations ofthe structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend tfiat obsen/ation and/or testing be perfomied by GSI at each of the following constmction 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. Priorto pouring any slabs orflatwork, after presoaking/presaturation of building pads and other flatwort< subgrade, before the placement of concrete, reinforcing steel, capillary break (I.e., sand, pea-gravel, etc.). or vapor bamers (i.e., visqueen, etc.). During retaining wall subdrain installation, priorto backfill placement. During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. During slope constmction/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. Mr. Edward E. Hagey W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18.2003 Rle:e:\wp9\3200\3213a.pge Page 36 GeoSoils, Inc. A report of geotechnical obsen/ation and testing should be provided at the conclusion of each of the above stages. In order to provide concise and clear documentation of stte work, and/or to comply with code requiremente. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, stmctural engineer, post-tension designer, archftect, landscape archttect, wall designer, etc., should review the recommendations provided hereiri, incorporate those recommendations Into all their respective plans, and by explldt reference, make this report part of their project plans. PLAN REVIEW Final project plans should be reviewed by this office prior to constiuction. so that constmction Is In accordance witii tiie condusions and recommendations of tills report. Based on our review, supplemental recommendations and/or fiJrther geotechnical studies maybe warranted. LIMITATIONS The materials encountered on the project sfte and utilized for our analysis are believed representative ofthe area; however, soil and bedrock materials vary in charader between excavations and natural outcrops or condrtions exposed during mass grading. Srte 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 pradice. and no warranty Is expressed or Implied. Standards of practice are subjedto change wfth time, GSI assumes no responsibilrty or llabllrty for wori< ortesting perfonned by others, ortheir inadlon. or work performed when GSl Is not requested to be onsite, to evaluate tf our recommendations have been properiy implemented. Use ofthis report constittJtes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements tiiat may be in piace. In addition, this report may be subject to review by the controlling authorfties. Mr. Edward E. Hagey ^ ^^.^f ^^SS APNs 155-140-37 and 155-140-38 September 18. 2003 RIe:e:\wp9^200\3213a.pge P^QB 37 GeoSoils, Inc. illUIU><l--OZ O Z IU O UJ _i QC O U. CO UJ 55 -I a UJ m xn UI-IUI><(--OZ n a n i " s g 5 lis i •- ^ u W o I I .a S XI II n 9 i; • t t *^ OOo B e e o o S S 4? o o u OOo 2 B a B S I 8 k. a a S 4 < < O o tt E O M O O CM «r CO' (9 o 1 • E M o a a 4 S ! 5- « « o £ 2 5^ IO 1- i CO m z s c o o u '5) o o e o •s 1 li O 3 E 1 i -s a a. o » • S ' o E * • • a o C i S S g o iS « o • a o a 3 < tr (1931) uottBAeig 35 CO <00|2 £ S 5 III I & I (0 O CO APPENDIXA REFERENCES APPENDIXA REFERENCES Benton Engineering, lnc.,1970. Final compaction report. La Costa Soutti unrt 7. August 10,1970. Projed No. 69-12-8D. Blake, T.F., 2000a, EQFAULT, A computer program forthe estimation of peak horizontal acceleration from 3-D faurt sources; Windows 95/98 vereion. _, 2000b. EQSEARCH, A computer program for tiie estimation of peak horizontal acceleration from Calrtomia historical earthquake catalogs; Updated to Decemtjer, 2002. Windows 95/98 version. , 2000c, FRISKSP, A computer program for ttie probabilistic estimation of peak acceleration and untfomn hazard spectra using 3-D faurts as earthquake sources; Windows 95/98 vereion. Bozorgnia, Y., Campbell, K.W., and Niazi, M., 1999, Vertical ground motion: Charaderistics, relationship wfth horizontal component, and building code Implications; Proceedings of ttie SMIP99 seminar on utilization of strong-motion data, September 15. Oakland, pp. 23-49. Campbell, K.W. and Bozorgnia, Y.. 1994, Near-source attenuation of peak horizontal acceleration from woridwide accelrograms recorded from 1957 to 1993; Proceedings, Frftti U.S. National Conference on Earthquake Engineering, volume III, Earthquake Engineering Research Institute, pp 292-293. GeoSoils. inc., 1993, Preliminary geotechnical evaluation, parcel 155-140-09, Carisbad, Califomia, W.O. 1624-SD. dated November 2. Hart. E.W. and Bryant, W.A. 1997. Fautf-rupture HazanJ Zones in Calrtornia, Alquist-Priolo Earthquake Faurt Zoning act witii Index to Earthquake Fautt Maps; Calrtomia Division of Mines and Geology Special Publication 42. Idriss, I.M., 1994. Attenuation coefficiente for deep and soft soil condftions; jn EQFAULT, A computer program forthe estimation of peak horizontal acceleration from 3-D fautt sources; Windows 95/98 version, Blake, 2000a. International Conference of Building Officials. 1997. Untfonn building code: Whittier, Califomia, vol, 1.2. and 3. Jennings, C.W.. 1994. Fautt activrty map of Calrtornia and adjacent areas: Califomia Division of Mines and Geology, Map Sheet No. 6. scale 1:750,000. GeoSoils, Inc. Joyner, W.B., and Boore, D.M., 1982a, Estimation of response-specfrai values as functions of magnrtude. distance and site condrtions, jn eds., Johnson, JA, Campbell, K.W., and Blake, T.F., AEG short course, seismic hazard analysis, dated June 18,1994. , 1982b, Prediction of earthquake response spedra, U.S. Geological Survey Open-Rle Report 82-977,16p. Kuhn, G.G., Legg, M.R., Johnson, J.A., Shiemon, R.G., and Frost, E.G., 1996, Paleo liquefaction evidence for large pre-historic eartiiquakes(s) in north-coastal San Dlego County, Calffornia, jn Munasinghe, T., and Rosenberg, eds., Geology and natural resources of coastal San Diego County, Califomia, guidet)ook to accompany the 1996 annual field frip ofthe San Dlego Association of Geologists, September. Obemneier, S.F;, 1996. Using liquefadion-lnduced features for paleoseismic analysis, Chapter 7. |n McCalpin, J.P,, ed, Paleoselsmology. Acedemic Press Petersen, Mari< D., Bryant, W.A., and Cramer, C.H., 1996, Interim table of fautt parametere used by the Calrtomia Division of Mines and Geology to compile the protjabllistic seismic hazard maps of Caltfornia. Sadigh, K„ Egan, J., and Youngs, R., 1987, Predictive ground motion equations reported in Joyner, W.B., and Boore, D.M., 1988, "Measurement, characterization, and prediction of sfrong ground motion," io Earthquake Engineering and Soil Dynamics ll, Recent Advances In Ground Motion Evaluation, Von Thun, J.L, ed.: American Society of Civii Englneere Geotechnical Spedal Publication No. 20, pp. 43-102. Tan, S.S., and Kennedy, Michael P., 1996, Geologic maps ofthe northwestern part of San Diego County, California: California Division of Mines and Geology, Open File Report 96-02, Mr. Edward H. Hagey Appendix A Rle:e:\wp9\3200\3213a.pge PagB 2 GeoSoils, Inc. APPENDIX B jikiHX)r?ATlidNS BORING LOG GeoSoils, Inc. W.O, 321»A-SC PROJECT:MR. TED HAGEY APNs 155-140-37 and 155-140-38. aty ofCarlsbad BORING B-1 Sample 35 CQ COM Q £ a i s a CO 0} DATEEXCAVATED SAMPLEMEmOD: HAND AUGER SHEET 1 OFl 1-9-02 Standard PenetraOon Test Undlsturixd, f^iy Smnpto Groundwater Description of Materiai SM ARTIi-ICIALnLL; @ 0-4" SILTY SAND, brown, damp to moist, loose; roottets. SM TERI^CE DEPOSITS: @ 4-5'SILTY SAND, reddish brown, slightly moist, medium dense. Total Depth = 5' No Groundwater Encountered Backfilled 1-9-2002 fiPNs 155-140-37 and 155-140-38. Oty of Carlsbad GeoSoils, Inc. PLATE B-1 BORING LOG GeoSoils, Inc. W.O. 3213-A«C P/?OJECT:MR.TED HAGEY APNs 155-140-37 and 155-140-38, City of Carisbad BORING B>2 £ a. 8 Sample i 1^ TJ O mS OB m >. Z3 CO E a 9 c s e 3 a m DATEEXCAVATED SJWPLE METHOD: HAND AUGER SHEET 1 OFj_ l-WC 22i Standmd Penetration Test UmSstutbed, Ring Sample ^ Groundwater Description of Material SM ARTIFICIAL FILL: @ 0-1'SILTY SAND, brown, damp, loose; rootlets. SM TEM^CE DEPOSITS: @ 1-4' SILTY SAND, reddish brown, moist, medium dense to dense with depth. 107.0 5.1 24.7 Total Depth = 4' No Groundwater Encountered Backfilled 1-9-2002 5- APNs 155-140-37 and 155-140-38. Cify of Carisbad GeoSoils, Inc. PLATE B-2 BORING LOG GeoSoils, Inc. W.O. 3213^-SC PRO/ECT;*^. TED HAGEY APNs 155-140^7 and 155-140-38. C^ of Carlsbad BORING B-3 Sample m 8| 3 Q a .9 i s I DATEEJfCAVATED SAMPLE METHOD: HAND AUGER SWEET 1 OFl 1-9-02 Startdofd Penetration Tesf UnOsliated, Rhg Sampfe Groundwater Description of Material SM COLLUVIUM/TOPSOIL; @ 0-Z SILTY FINE SAND, brown. dry, toose; well rounded coarse pebbles. SANTIAGO FORMATION fTSA); @ 2-3' CLAYEY SANDS I (JNt. redish brown to light brown, moist, medium dense. ! 3-4J4' grades to SANDSTONE, light brown, moist, dense. 5- TotalDepth=4%' No Groundwater Encountered BackfUled 1-9-2002 APNs 155-140-37 and 155-140-38. City of Cartsbad GeoSoils, Inc. PL4TE B-3 BORING LOG GeoSoils, Inc. W.O. 3213-A-SC PROJECT:MR. TED HAGEY APNs 155-140-37 and 155-140-38. City of Carisbad BORING B-4 Sample 3a o m 8| 3 . a I o S a o CO OATE BOCA VMTBJ SAMn^ METHOD: HAND AUGER SHEET 1 OFl 1-9-02 Standard Penetration Test Undlsturt)ed, Ring Sample 2 Groundwater Description of Material SM COLLUVIUM: @ 0-1 Mi' SILTY SAND, brown, dry, loose; rootles. SM OLDER ALLUVIUM; @ VA-5' SILI Y FINE SAND, reddish brown, moist, toose to medium dense. Total Depth = 5' No Groundwater Encountered Backfilled 1-9-2002 APNs 155-140-37 and 155-140-38. Cify of Carisbad GeoSoils, Inc. PL4TE B-4 BORING LOG GeoSoils, Inc. W.O. 3Z^S•ArSC PROJECT:MR. TED HAGEY APNs 155-140-37 and 155-140-38. City of Carisbad BORING B-5 Sample i la 3(0 5^ ±f a. c —' 3 £• Q & a ss S a m CO SAMPUE METHOD: DATEEXCAVATED HAND AUGER SHEET 1 OFl 1-9-02 Standard Penetreffon Test Un<Bs^urbed, Ring Samfde S &oundwater Description of Material SM COLLUyiUMn;OPSOIL: @ 0-2' SILTY SAND, brown, dry. loose; rootlets, rounded coarse pebbles. SANTIAGO FORMATION (TSA): @ 2-4' CLAYEY SANDSTONE, reddish brown to light brown, moist, loose to medium dense. Total Depth = 4' No Groundwater Encountered BacfcRlled 1-&-2002 APNs 155-140-37 and 155-140-38, Cily of Cartsbad GeoSoils, Inc. PLATE B-5 GEOSOILS, IMC. BORING LOG CLIENT MICH2VEL REED WORK ORDER MO. gARCBL 155-140-09, CARLSBAD DATE EXCAVATED SAMPLE HETHOD AUGER DRILLING RIQ BCWIMG MO. B-1 30" DIAMETER BUCKET 1624-6D 10-21-93 SHEET 1 OF 2 SAMPLE aa ^ 0. L a DESCRIPTION DF MATERIAL SM 10 SM SM 123.3 111.5 7.4 5.4 y 0-1' TOPSOIL! Dark yellowish brown silty \SAND; dry, loose, hard and porous, trace ; \rootlets. 61' TERRACE DEPOSITS (Ot) ! Reddish brown medium dense. silty SAND; slightly mois @2' Becomes moist. @5' Yellowish brown fine SAND with some silt; slightly moist, medium dense. SP 100.0 4.2 15- 20 125.3 11.4 ^4 10 128.2 10.3 §10' Brownish yellow, clean fine SAND with trace well rounded pebbles; slightly moist and meditua dense. @13.5' Grades to clean fine SAND with well rounded cobbles. @15' Becomes fine SAND. \@16' Abrupt, approximately horizontal basalJ \contact. / @16' -SANTIAGO FORMATION (Tsa): Light gray SANDSTONE with trace clay; moist and medium dense to dense. §18'-19' Zone of slight water seepage into boring. @19' Sandstone becomes denser. 25- 20 118.5 14.0 30- 35 1^ FORM 88/9 §23.5' Abrupt, and approximately horizontal contact of SANDSTONE over light olive brown sandy CLAYSTONE; slightly moist and very stiff, with randomly oriented irregular xpolished fracture surfaces. ^ §27'-28' Gradational, approximately horizontal transitional zone from claystone to light gray S2^DST0NE; moist and dense. §33' Observed water seepage into hole from near vertical fracture in SANDSTONE, fracture trends north 35 degrees east. §34' Becomes very moist, slight seepage from boring sidewalls observed to bottom of boring. Piate B-6 GEOSOILS, INC. CORING LOG CLIENT. MICmEL REED WORK ORDER NO. PARCEL 155-140-09, CARLBBAD DATE EXCAVATED SAMPLE METHOD AUGER DRILLING RIG BORINQ MO. B-1 30" DIAMETER BUCKET 1624-SD 10-21-93 SHEET 2 OF 2 SAMPLE I T> n a - JJ TJ L C 3 co N 3 O O VI Ji o e m 3> 3 m +- 3 51 L a 0 r DESCRIPTION OF MATERIAL 45 50- 55- 60- 65 70- 75 30 121.9 13.0 -4re- 6" 114.6 16.6 FORM 88/9 ,§52' Increased seepage into boring from \SANDSTONE. §52.5' Olive brown fractured claystone; slightly moist to moist and very stiff. 1 tv §54' Light yellow gray SANDSTONE; moist to ery moist, dense. Total depth= 55 feet Seepage at 18 to 19 feet and below 34 feet Increased seepage at 52 feet No caving Hole backfilled i Plate B-7 HAND AUGER LOG Hand Auger Deptii fft.) IWaterial Description HA-1 0-1 TOPSOiL Yellowish brown silty fine SAND; dry. loose, porous, friable, few rootlets. 1 -1 -5 TERRACE DEPOSiTS (Qt): Red brown silty SAND; sligiitly moist, loose to medium dense, slightly hard. 1 -5-2 Becomes slightly moist to moist and medium dense. Total depth = 2 feet No groundwater Hole backfilled ^^'^ O-l COLLUVIUM: Brown sandy SILT; dry. loose, few roots. 1- 2 TERRACE DEPOSITS {QtV. Red brown fine SAND with some well rounded pebbles; slightly moist, loose to medium dense, friable. 2- 7 SANTIAGO FORMATION (Tsa)! Light yellow gray fine grained SANDSTONE; slightly moist to moist, medium dense. Total depth= 7 feet No groundwater Hole backfilled Plate B-8 MR. MICHAEL REED NOVPMRFR 9 loo-a W.O. 1624.SD NOVEMBER 2, 1993 HAND AUGER LOG Hand Auger Deoth ffl.) Material Description HA-3 0-2 HA-4 0-1.5 COLLUVIUM: Dark brown silty fine SAND with some well rounded coarse pebbles; dry, loose. 2-3 SANTIAGO FORMATION fTsaV Red brown SANDSTONE with some clay; moist, loose to medium dense. Grades to yellow brown SANDSTONE; moist, medium dense. Total depth= 8 feet No groundwater Hole tsackRiied COLLUVIUM: Brown silty SAND; dry and toose. OLDER ALLUVIUM fOnn)- Red brown silty fine SAND; moist, loose to medium dense. ''•^•^ SANTIAGO FORMATION (Tsa)- Yellow brown SANDSTONE; mdst. medium dense. Total depth= 8 feet No groundwater Hole backfilled Plate B-9 APPENDIX G iOFAULt, EbSEAFlCH, AND FRI3K^P s c ,o 05 !_ 0 O O < MAXIMUM EARTHQUAKES Hagey Residence 1 -= 1 -= .01 -= .001 1 1 10 Distance (mi) 100 W.O. 3213-A-SC Plate C-1 CO 0 >- 42 c HI 0 E u Z 0) > E E 3 o 100 EARTHQUAKE RECURRENCE CURVE Hagey Residence .001 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Magnitude (M) W.O. 3213-A-SC Plate C-2 EARTHQUAKE EPICENTER MAP Hagey ReskJence 1100 1000 - - 900 - -, 800 700 -- 600 500 -- 400 300 200 100 0 -- -100 -400 -300 -200 -100 300 400 500 600 W.O. 3213-A-SC Piate C-3 PROBABILITY OF EXCEEDANCE BOZ. ET AL(1999)HOR SR UNC 1 100 25 yrs 75 yrs 50 yrs 100 yrs 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Acceleration (g) W.O. 3213-A-SC Plate C-4 (SJA) poued ujnjey W.O. 3213-A-SC Plate C-5 (SJA) pousd mnjay APPENPrXD i.- z te. B: s •• r- • tn \ J t f \ 1 i ,,^y^ •< : , '} . * .-• •' • ' • V * * 'j • J . •• •• .. ' • .... • . • 1 'i . " • I*"* • ' * "• ' - 0 500 1,000 1,500 . 2.000 NORMAL PRESSURE, psf .2,500 .3.00P Sample Depth/EL Primaryfftesldual Shear Sample Type Yd MC% C • B-1 0.0 Primaiy Shear Remolded 107.9 5.1 317 33 • 6-1 0.0 Residual Shear Remolded 107.9 5.1 275 33 Note: Sample Innundated prior to testing GeoSoils. Inc. 5741 Palmer Way Carlsbad. CA 92008 Telephone: (760)438-3155 Fax: DIRECT SHEAR TEST Project: HAGEY Number: 3213-A-SC Date: January 2002 Plate D-1 APPiNDIXE SLdPi^TABiy 2-DIMENSIONAL SLOPE STABILITY ANALYSIS INTRODUCTION OF GSTABL7 v.2 COMPUTER PROGRAM Introduction GSTABL7 v.2 Is a iiilly Integrated slope stability analysis program. It permits the engineer to develop the slope geometry Interactively and perfonn slope stability analysis fi'om within a single program. The slope analysis portion of GSTABL7 v.2 uses a modified version of the popular STABL program, originally developed at Purdue University. GSTABL7 v.2 performs a two dimensional limit equilibrium analysis to compute the factor of safety for a layered slope using the simplified Bishop or Janbu methods. This program can be used to search for the most critical surface or the factor of safety may be determined for specific surfaces. GSTABL7, Version 2, is programmed to handle: 1. Heterogenous soil systems 2. Anisotropic soil strength properties 3. Reinforced slopes 4. Nonlinear Mohr-Coulomb strength envelope 5. Pore water pressures for effective stress analysis using: a. Phreatic and piezometric surfaces b. Pore pressure grid c. Rfector d. Constant pore water pressure 6. Pseudo-static earthquake loading 7. Surcharge boundary loads 8. Automatic generation and analysis of an unlimited number of circular, noncircular and block-shaped failure surfaces 9. Anal^reis of right-facing slopes 10. Both SI and Imperial units General Information If the reviewer wishes to obtain more information conceming slope stability analysis, the following publications may be consulted initially: 1. The Stabilitv of Slopes, by E.N. Bromhead, Sun-ey University Press, Chapman and Hall. N.Y.. 411 pages, ISBN 412 01061 5,1992. 2. Rock Slooe Engineering, by E. Hoek and J.W. Bray, Inst, of Mining and Metallurgy, London. England. Third Edition, 358 pages, ISNB 0 900488 573,1981. 3. Landslides: Analvsis and Control, by R.L Schuster and R.J. Krizek (editors). Special Report 176, Transportation Research Board, National Academy of Sciences, 234 pages, ISBN 0 309 02804 3,1978. GeoSoiUf Ine. GSTABL7 v.2 Features The present version of GSTABL7 v.2 contains the following features: 1. Allows user to calculate factors of safety for static stabilrty and dynamic stability situations. 2. Allows user to analyze stability situations with different failure modes, 3. Allows user to edit input for slope geometry and calculate corresponding factor of safety. 4. Allows user to readily review on-screen the Input slope geometry. 5. Allows user to automatically generate and analyze unlimited number of circular, non-circular and block-shaped fsulure surfaces O.e., bedding plane, slide plane, etc.). Input Data Input data includes the following items: 1. Unit weight, residual cohesion, residual friction angle, peak cohesion, and peak friction angle of fill material, bedding plane, and bedrock, respectively. Residual cohesion and friction angle is used for static stability analysis, where as peak cohesion and friction angle is for dynamic stability analysis. 2. Slope geometry and surcharge boundary loads. 3. Apparent dip of bedding plane can be specified in angular range (i.e., from 0 to 90 degrees. 4. Pseudo-static earthquake loading (an earthquake loading of 0.12 / was used in tiie analysis). Seismic Discussion Seismic stability analyses were approximated using a pseudo-static approach. The major difficulty in the pseudo-static approach arises from the appropriate selection ofthe seismic coefficient used in the analysis. The use of a static inertia force equal to this acceleration during an earthquake (rigid-body response) would be exh'emely conservative for several reasons Including: (1) oniy low height, stiff/dense embanl^ments or embankments in confined areas may respond essentially as rigid structures; (2) an earthquake's inertia force is enacted on a mass for a short time period. Therefore, replacing a transient force by a pseudo-static force representing the maximum acceleration is considered unrealistic; (3) Assuming tiiat total pseudo-static loading is applied evenly throughout the embankment Mr. Edward H. Hagel Appendix E R!e:e:\wp9\32oa0213a.pge Page 2 OeoSoilSf Ine. for an extended period of time is an incorrect assumption, as the length of the failure surface analyzed Is usually much greater than the wave lengtii of seismic waves generated by earthquakes; and (4) the seismic waves would place portions of the mass in compression and some in tension, resulting In only a limited portion ofthe failure surface analyzed moving in a downslope direction, at any one instant bf time. The method developed by Krinitzsky, Gould, and Edinger (1993) which was in tum based on Taniguchi and Sasaki, 1986 (T&S, 1986), was referenced. This metiiod is based on empirical dafa and the perfonnance of existing earth embankments during seismic loading. Our review of "Guidelines for Evaluating and Mitigating Seismic Hazards in Califomia (Davis, 199^ Indicates tiie State of California recommends using pseudo-stetic coefficient of 0.15 fbr design earthquakes of M 8.25 or greater and using 0.1 for earthquake parameter M 6.5. Therefore, for conservatism a seismic coefficient of 0.12 / was used in our analysis. Output Information Output information includes: 1. All input dafa. 2. Factorsofsafetyforthetenmostcriticalsurfacesforstaticand pseudo-static stability situation. 3. High quality plots can be generated. The plots include the slope geometry, the critical surfaces and the factor of safety. 4. Note, that in the analysis, a minimum of 100 trial surfaces were analyzed for each section for either static or pseudo-static analyses. Results of Slope Stebilitv Calculation Table E-1 shows parameters used in slope stability calculations. Summaries ofthe slope sfabllity analysis are presented in Table E-2. Detailed output information is presented in Plates E-1 to E-4. A typical cross-section representing the highest proposed fill slope at a gradient of 2:1 (h:v) was utilized for analyses. Mr. Edward H. Hagel Appendix E File:e:\wp9\K00\3213a.pge Page 3 Ir^oSoils, Inc. TABLE E-1 SOIL PARAMETERS USED TABLE E-2 SUMMARY OF SLOPE ANALYSIS 4'ihg'r5ri.^r1!f::j;;^N4:i-;.>rlig<^f::^^ 1 I mm ii,fSLopei MllGRADli^Ti if! -.T.irf ISEISMICi Gross ±65-Foot High Native Slope 2.5:1 to 4.5:1 2.80 2.00 Gross ±65-Foot High Native Slope 2.5:1 to 4.5:1 2.12 1.54 Mr. Edward H. Hagel File:e:\wpg\3200\3213a.pge Appendix E Page 4 GeoSoilSf Ine, <s I— 00 (/> . to m QQ CO I -J 2S I-O UJ </) m ri CM ro C3 < ^3 Oooo w •sgf«o;-ic>j 22 ww id'ri 3^ a.CM CM CM •gS^'<--r-t- m^ip <=»«?<=> t— ^ T— T— -r- — (D . 9 (0 1^20 Weooooooocococqcooocq * 19X1 o-o 9"- OJ: • X 5 o U) o o O CM O O CM n o f S a o JC JO Dd x» CM DQ > -o ^Jl5 S 3 155 o H o o o in o in CM o o CM O in o o rH O tn o 5 o u. (0 W.O. 3213-A-SC Plate E-1 <0 ca cr 83.N! X o - § ^^dooo a. 3 w c .„ 8 8§5-aci JC m £i>Q S O •a „ o o o o I ' X— r- ooo .-= tS o 5 1^5 Woooooooooq It OTD O"^ ox: . CO o IO CM o o CM o •o o n CM o o o in o o o IO •o o £ e S a. o » EQ •o il El "•^ CM CQ > "O 10 3 u o !0 o IS u. 15 (0 W.O. 3213-A-SC Plate E-2 "J _ tn. o m - " o UJ CD **" ffl Z C _ 3 O DC 3 Q. I- o UJ CO CO CM >• UJ X 51 8 W •c 5 rf "> U- ^ ^ 8 gf d.Sd t— ^ ^f— T- s 0> • O & O-r- CM CO g o ^ _.«>o OH- CMO CM •* W 10 K N W "-c>loic>ic>irJc>5r4c4c>ic4 (OXI. UTJ »»- ojr . O o IO CO o o CO o IO CM o o CM O in o A o SX £ Q. o "5 o S o £ T3 O n ^ C 3 (0 i5 u. -> ^1 w 2 o jE >• m •o <)> 3 O w O o in o in CM o o CM O IO o o o IO u. (0 W.O. 3213-A-SC Plate E-3 D CQ CO CO UJ o co§ . - UJ CO o ffl ffl c z s r~ D. O CO Ul E W ^ CO Q Si >-1 Ul [u . V ®'H ra 3 "^o O I _^ T-So o o a. 3^ CO 8§fo.g ooo dgc> 2^ ommio acMCM CM to-" ooo „ wd c>d acMCMCM ,n So «CMCDNCMC03:I0 u. ft wxi o -o (0 »- rax: . o o o in CO o o CO o in M o o CM o in O o o lO o m CM o o in s o in o A £ o ja £ a u o 8 £ •o o £ ITS CM (0 2 0|E >> m •o JS 3 _o o I 2 5 u 10 u. f (0 W.O. 3213-A-SC Plate E-4 APPENDiXF GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on tiie approved grading plans, including preparation of areas to filled, placement of fill, installation of subdrains and excavations. The recommendations contained in tiie geotechnical report are part ofthe eartiiwork and grading guidelines and would supercede the provisions contained hereafter In tiie case of conflict. Evaluations performed by tfie consultant during tiie course of grading may result in new recommendations which couid supersede these guidelines or tiie recommendations contained in the geotechnicai report. The contractor is responsible forthe satisfactory completion of all eartiiwork in accordance with provisions of the project plans and specifications.. The project soli engineer anci engineering geologist (geotechnical consultant) ortheir representatives shouid provide observation and testing services, and geotechnical consultation during the duration of tiie project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed forthe 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 toting and obsen/ation so that determination may be made tiiat 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 acxiprdlngiy. 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 fiil. It is the contractors's responsibility to notify the engineering geologist and soil engineer when such areas are ready for observation. Laboratorv 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-1557-78. Random field compaction tests should be performed in accordance with test method ASTM designation D-1556-82, D-2937 or D-2922 and D-3017, at Inten/als of approximately 2 feet of fill height or every ICQ cubic yards of fill placed. These ca-iteria 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 geotechnics consultant. GeoSoilSy Ine, Contractor's Responsibility All clearing, site preparation, and eartiiwork perfonned on tiie project should be conducted by tiie contractor, witii observation by geotechnical consultants and staged approval bythe governing agencies, as applicable. It is tiie contactor's responsibility to prepare the ground surface to receive the fill, to the satistection of tiie soil engineer, and to place, spread, moisture condition, mix and compact the fill in accordance with the recommendations of the soil engineer. The conti-actor shouid also remove all major non-eartti material considered unsatisfactory by the soil engineer. It is the sole responsibility of tiie contractor to provide adequate equipment and metiiods to accomplish the earthwork in accordance with applicable grading guidelines, codes or agency ordinances, and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided bythe conti-actor with due consideration for the fill material, rate of placement, and climatic conditions. If, in tiie opinion ofthe geotechnical consultant, unsatisfactory conditions such as questionable weatiier, excessive oversized rock, or deleterious material, insufficient support equipment, etc., are resulting in a quality of woric that is not acceptable, the consultant will inform the contractor, and tiie contractor is expected to rectify the cxjnditions, and If necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade ail surfaces to maintain good drainage and prevent ponding of water. The conti-actor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion conti-ol measures have been instaiied. SITE PREPARATION All major vegetation. Including brush, ti-ees, 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 soii engineer or engineering geologist as being unsuitable in-place should be removed prior to 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 soil engineer. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other stmctures not located priorto grading are to be removed or treated in a manner recommended bythe soil engineer. Soft, dry, spongy, highly fractured, or othenwise unsuitable ground extending to such a depth that surface processing cannot adequately improve the condition should be overexcavated down to fimri ground and approved by the soil engineer before compaction and filling operations continue. Overexcavated and processed soils which have been properiy mixed and moisture conditioned should be re-compacted to the minimum relative compaction as specified in these guidelines. Mr. Edward H. Hagey Appendix F Rle:e:\wp9\3200\3213a.pge Page 2 GeoSMSf Ine. Existing ground which is detenmlned to be satisfactory for support of tiie fills should be scarified to a minimum depth of 6 inches or as directed by tlie 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 inc^hes in depth, It may be necessary to remove the excess and place the material in lifts restilcted to about 6 Inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill shouid be overexcavated as required in the geotechnic^al report or by Ihe on-site soils engineer and/or engineering geologist. Scarification, disc harrowing, or otiier acceptable fomn of mixing should continue until the soils are broken down and free of large lumps or clods, until the working surfece is reasonably uniform and firee from ruts, hollow, hummocks, or otiier uneven features which would Inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 3:1 (horizontal to vertical), the ground should be stepped or benched. The lowest bench, which will act as a key, shouid be a minimum of 15 feet wide and should be at least 2 feet deep into firm materiai, 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 Geotechnicai Consultant. As a general rule. Unless specifically recommended othenwise by the Soil Engineer, the minimum width of fill keys should be approximately equal to Vz the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing fimn, acceptable material. Benching may be used to remove unsuitable materials, although it Is understood thatthe vertic^ height ofthe bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. Aii areas to receive fiil, including processed areas, removal areas, and the toe of fill benches should be observed and approved by the soil engineer 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 eartfi materials imported or excavated on the property may be utilized In the fill provided that each material has been detemnined to be suitable bythe soil engineer. These materials should be free of roots, tree branches, other organic matter or other deleterious materials. All unsuitable materials should be removed fi-om the fill as directed by the soil engineer. Soils of poor gradation, undesirable expansion potential, or substandard strengtii characteristic's may be designated by the consultant as unsuitable and may require blending witfi other soils to sen/e as a satisfactory fill material. Mr, Edward H. Hagey Appendix F Re:e:\wp9\3200\3213a.pge Page 3 GeoSoils, Ine. Rll materials derived fix>m benching operations should be dispersed throughout tiie fill area and blended with other bedrock derived material. Benching operations should not result In tiie benched material being placed only within a single equipment width away from the fill/bedrock confect. Oversized materials deflned as rock or other in^eductbie materials witii a maximum dimension greater than 12 inches should not be buried or placed in fills unless the loc:ati'on of materials and disposal methods are spec^ificaliy approved by tiie soii engineer. Oversized material shouid be taken off-site or placed in accordance with recommendations ofthe soii engineer in areas designated as suitable for rcx^k disposal. Oversized material should not be placed within 10 feet vertically of finish grade (elevation) or within 20 feet horizontally of slope faces. To facilitate future ti-enching, rock should not be placed within the range of foundation excavations, futijre utilities, orunderground 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 fiil should be analyzed in the laboratory by the soil engineer to detemnine its physical properties. If any material other than that prevkausly tested Is encountered during grading, an appropriate analysis ofthis 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 layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Rll layers at a moisture content less than optimum shouid 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 fiil 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 maximum density as determined by ASTM test designation, D-1557-78, or as otherwise recommended bythe soil engineer. Compaction equipment should be adequately sized and should be specifically designed for soil compaction or of proven reliability to efllciently achieve the specified degree of compaction. Where tests indicate that tiie density of any layer of fill, or portion tiiereof, is beiow the required relative compaction, or improper moisture is in evidence, the particular layer or portion shall be re-wori<ed 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 Mr. Edward H. Hagey Appendix F Rle:e:\wpg^200\3213a.pge Rage 4 GooSoils, Itw. tested and found to meet tiie 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 tirlmming back to the design slope configuration. Testing shall be perfomied as the fill is elevated to evaluate compaction as the fill core is being developed. Special efi'orts may be necessary to attain the specified compaction In the fill slope zone. Rnal slope shaping should be peribmned by tiimming and removing loose materials with appropriate equipment. Afinal detennination of fill slope compaction shouid be based on obsen/ation and/or testing of tfie finished slope face. Where compacted fill slopes are designed steeper than 2:1 (horizontal to vertical), specific materiai types, a higher minimum relative compaction, and special grading procedures, may be recommended. if ah alternative to over-buijding and cutting back the compactedfill slopes is selectsd, tiien special efl'ort should be made to achieve the required compaction In the outer 10 feet of each lift of fill by undertaking tiie foliowing: 1. An extra piece of equipment consisting of a heavy short shanked sheepsfoot shouid be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller shouid 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 shouid not t>e spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed siope 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 siope at appropriate verti'cai intervals, subsequent to compaction operations. 4. After completion of the slope, the siope face shouid be shaped with a small tractor and then re-roiled witti a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to vertfy compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to confinn compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix and re-compact tiie siope material as necessary to achieve compaction. Additional testing shouid be performed to verify compaction. 6. Erosion control and drainage devices should be designed by the project civil engineer In compliance with ordinances ofthe controlling govemmental agenctes, and/or In accordance with the recommendation ofthe soil engineer or engineering geologist. Mr. Edward H. Hagey Appendix F F=He:e:\wp9\3200\3213a.pge Page 5 Get^iU, Ine. SUBDRAIN INSTALLATION Subdrains should be Instaiied In approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Sulxirain locations or materials should not be changed or modified without approval of the geotechnical consultant. The soil engineer and/or engineering geologist may recommend and direct changes in subdrain line, grade and drain materiai in the field, pending exposed conditions. The location of constructed subdrSns should be recorded bythe project civii engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the engineering geologist. If directed by the engineering geologist, fijrtiier excavations or overexcavation and re-filling of cut areas shouid be performed and/or remedial grading of cut slopes should be perfonned. When fill over cut slopes are to be graded, unless otherwise approved, the cut portion ofthe slope should be observed bythe engineering geologist priorto placement of materials for construction ofthe fill portion ofthe slope. The engineering geologist shouid observe ail 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, tiie engineering geologist and soil engineer should investigate, evaluate and make recommendations to ti-eat these problems. The need for cut slope birttressing or stabilizing should be based on in-grading evaluation by the engineering geologist, 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 govemmental 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 In compliance with the ordinances ofthe conti-olling govemmental agencies, and/or In accordance wfth the recommendations of the soii engineer or engineering geologist. COMPLETION Observation, testing and consultation bythe 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 soii engineer and engineering geologist have finished their obsen/ations ofthe wortc, final reports should be submitted subjectto review Mr. Edward H. Hagey ' Appendix F File:e:\wp9^Z0O\3213a.pge Page 6 OeoSoiHt Ine. by the conti-olling governmental agencies. No further excavation or filling should be undertaken without prior notification of the soil engineer and/or engineering geologist Ail finished cut and fiil slopes should be protected fix>m erosion and/or be planted in accordance wftti 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 ail employees on multi-employer construction sites. On ground personnel are at highest risk of injury and possible fatality on grading and consbuction projects. GSI recognizes that constiruction activities will vary on each site and that site safety is the orime responsibility of the contractor; however, everyone must be safety conscious and responsiljie at all times. To achieve our goal of avoiding accidents, cooperation between the client, the contractor and GSI personnel must be maintained. In an efl'ort to minimize risks associated with geotechnical testing and observation, the foliowing precautions are to be Implemented forthe safety of field personnel on grading and constmction projects: Safety Meetings: GSI fieid personnel are directed to attend contractors regulariy scheduled and documented safety meetings. Safety Vests: Safety vests are provided for and are to be wom by GSI personnel at ail times when they are working in the field. Safety Flags: Two safety flags Eire provided to GSl 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: Aii vehicles stationary in the grading area.shall use rotating or flashing amber beacon, or strobe lighfe, on the vehicle during ali field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the eventthatthe contractor's representative observes any of our personnel notfollowing the above, we request that rt be brought to the attention of our office. Mr. Edward H. Hagey Appendix F Rte:e:\wp9^3200\3213a.pge Page 7 GooSof ISy Ine. Test Pits Location. Orientation and Clearance The technidan Is responsible for selecting test pit locations. A primary concem should be the technicians's safety. Efforts will be made to coordlnat^ locations wtth the grading contiractors authorized representative, and to select locations foiiowing or behind the established traffic pattem, preferably outside of cunent tiraffic. The contractors authorized representative (dump man, operator, supen/isor, grade checker, etc.) shouid direct excavation ofthe ptt and safety during tiie test period. Of paramount concem should be the soil technicians safety and obtaining enough teste to represent the fiil. Test ptts should be excavated so thatthe spoil pile is placod away fomn oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test ptt, oppostte the spoil pile. This necessitates the fiil be maintained in a driveable condttion. Altematively, the contractor may wish to park a piece of equipment In front ofthe test holes, particularly in small fill areas or those wtth limtted access. A zone of non-encroachment should be established for all test ptts. No grading equipment should enter this zone during the testing procedure. The zone shouid extend approdmately 50 feet outward from the center of the test ptt. This zone is established for safety and to avoid excessive ground vibration vi/hich typically deca^eased test resutts. When taking slope tests the technician shouid park the vehicle directiy above or below tiie test location. If this Is not possible, a prominent flag should be placod at the top of the slope. The contractor's representative shouid effectively keep ali equipment at a safe operation distance (e.g., 50 feet) away fi-om the siope during this testing. The technician is directed to wfthdraw fi-om the active portion ofthe fill as soon as possible foilowing testing. The technician's vehicle should be parked at the perimeter ofthe fill In a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of ail changes to haul roads, cut and fill areas or other factors that may affect stte access and stte safety. In the event that the technicians safety Is jeopardized or compromised as a resutt of the contractors failure to comply wfth any ofthe 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 sttuation is rectified. Any fill place can be considered unacceptable and subject to reprocessing, recompaction or removal. In the event that the soil technician does not comply wtth the above or otiier established safety guidelines, we request that the contractor brings this to his/her attention and notify this office. Effective communication and coordination between tiie contractors representative and the soils technician is strongly encouraged in order to implement the above safety plan. Mr. Edward H. Hagey Appendix F Fite:e:\wp9\3a00\3213a.pge Page 8 GeoSoils^ Ine. Trench and Vertl<?al Excavation tt is the contractor's responsiblltty to provide safe access into trenches virtiere compaction testing is needed. I 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 instabiitty, has any loose rock or otfier debris which could fall Into the trench; or 3) displays any other evidence of any unsafe condttions regardless of depth. Ali trench excavations or vertical cute in excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance wtth 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. tf the contractor falls to provide safe access to trenches for compaction testing, our company policy requires that the soil technician virithdraw and notify his/her supervisor. The conti-actors representative will eventually be contacted in an effort to effect a solution, Ali backfill not tested due to safety concems or other reasons could be subjectto reprocessing and/or removal. \f 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 correctthe sttuation. If con-ective steps are nottaken, GSI then has an obligation to notify CAL-OSHA and/or the proper auttiorities. Mr. Edward H. Hagey Appendix F F8e:B:\wp9\3200\K13a.pge " - Page 9 GooSoils, Ine. Ui z I- LU Q < r) < LL. Q Ul z 5i BE Q: BE TEI z 3 LU O Ul CO o ITIO o LU O Ul CO o ONO tn _J o TION WOU SEO < INS o o INS OL z INS X Ul < Ul DR z r-1 ECO • tc Ul tOF UPI z o te. u. >-u. Ul CTION CTION OF Ul Ui -3 0 0 1-'tc CL 0 Z 1- Ul ILT Z OP z> m z _j z> m z cn z u. < 0 z Ui 0 < 0 z Ul I-? g > z 0 g > 0 X 0 to tn cc tu in CL a < PLATE EG-6 LU Q O OH LU O a z Bi 2 . S 5 Ul S 5 z H u 13 K X z ? UJ UJ ii- ui K ^ CQ O q a i < 5 a _ Ul 2 H D. ~ U § § i tn Ul £r u. Ul X I-o z g 3 P S u. " O Ul = £ p >- JJ; EO 2 ° «*• m I- I- =» ^ tn z o u ir o K O. U) a o -J -I Ul < o X > Ul I- Ul o ui i-o z PLATE EG-7 < cc LU UJ GQ to cr o LL LL o < 55 < CO yj ce o ^ O 5 CD u £ o o Ul 0 <A ^ z Ul S — tL a K O Z Ui -I UJ Ui y> ^ Z n. s O 1 S S Ul 5 cc H-O Ul Ul a 8! < "* n tc 9. Ul 5 Ul oc Ul Ul 5 Z ttl i i= 3 (A 5J ID Z «» Ul 13 = *'> O I- in X >• S m Ul a = U ttl s 3 Ui M 0. ^ Ul DC Ul £ z s 3 Z Ul 5 5 o Ul 5 . z z >• »-ta u, a «A X Ul 0- CO UJ • Q .J K < m I m Ut Z -i Ul a »- a o z UI Ul < cn z < < ee z Q (A CD .-=» 5 UJ • Ul < U) I- Ul ^ Ul u. »- Z -I < o X Ui • • Ul I-o z PLATE EG-8 Q O IT O -J < CC ZD < LL O LL to Ul o o o Ul z z tc Ul Ul ° u: !i: U a a Ul q z —' o o Vi ce, o Ul z »- S • Ul UJ ^ m Ui S 3 1 t 3 Z a o Ul ^ I Q. 8 « g 3 i i M 5 •* u. < e 7 QL Ui o Z UJ o z a u 5 Ul Ul z «« K UJ tn a IA . z -I o g z « o 2 Ui 3= o < I- Ui > ^ o < i; 0 " CO 1 i ^ cc DC 2 Ul Ul i% Ul > Ul Z O IU S Q CJ Z < Ul Ui a. z PLATE EG-9 Ul u if tr 3 Vt ta U) a Ui U) o Q. X Ul a Ul IA < CQ a m z z tc Ul I-ui a Ul CQ Ui \-z Ul z Ul a S a Ul cr a >- Ul id a z < z < oc a ta >- CQ >• ce < in tn UJ u UJ z a UJ z z o: Ut Ul a o Ul z ce s . oc »-Ul u» o. S Ul q « o a Ui -J o 2 z z: ^ S Ul Ul a z UJ u S z => h- o CO u z ''^ u UJ CL " > Z Ul 0 O I- & s tt n» tt W „ 2 "» 9 5 1 5 I 5« Z ^ £> O K XPS $ S 5 < 5 Zoz < X UJ in w tn o Ul 5 t > S z a Of o < X o a UJ H O z PLATE EG-10 TRANSITION LOT OETAIL CUT LOT (MATERIAL TYPE TRANSITION} NATURAL GRADE COMPACTED RLL OVEREXCAVATE AND RECOMPACT ^ 'm:^yp^^3p^^ MINIMUM* ^ UNWEATHERED BEDROCK OR APPROVED MATERIAL TYPICAL BENCHING CUT-HU. LOT (DAYUGHT TRANSITION) PAD GRADE NATO IUL GRADE ^^<c^ COMPACTED RLL '^'"K;^'^2>^bVEREX€AVATE AND RECOMPACT 5;MIJ|MUM f/7^^/^r/^0^^^/<m 3- MINIMUM^ J*^ TYPICAL BENCHING )^ UNWEATHERED BEDROCK OR APPROVED MATERIAL 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 DIAGRAM SIDE VIEW ( NOT TO SCALE ) TOP VIEW 100 FEET 50 FEET SPOIL TEiST PIT^: !i! u. o in 50 FEET AIVROXIMATE CENTER QF TEST PIT J L-i. iii u. o in FUG ( NOT TO SCALE ) PLATE EG—16 UPDATE PRELIMINARY GEOTECHNICAL EVALUATION APNS 155-140-37 AND -38, JEFFERSON STREET CJTY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA FOR MR. TED HAGEY P.O. BOX 99961 SAN DIEGO, CALIFORNIA 92169-3961 W.O. 5701-A-SC JUNE 17, 2008 Geole^iirtimf * C^IQ^^^ • Goastel • iiwlronmental 5741 Palmer• CaHsbad; ©atifetWa 92^^ . {7^3^ 438*3155 • F%X (760| 931-0915 June 17, 2008 W.O. 5701-A-SC Mr, Ted Hagey P O . Box 99^61 San Diego. Calffornfa 92169-3061 Subject: Update Preliminary Geotechnical Evaluatien, APNs 155-140-37 and -38, Jefferson Street, City of Carlsbad, San Dlego County, California Dear Mr. Hagey: In accordance with your request and authorization, GeoSoils, Inc. (GSl) has prepared this repori for the purpose of updating the preliminary geotechnical report (GSI, 2003) In light of the proposed constmction. Unless specifically superceded in the text ofthis report, the conclusions and recommendations presented in GSI (2003) should be considered valid and applicable. SCOPE OF SERVICES The scope of our servlGes has included the following; 1. Review of the available geologic literature for the site (see the Appendix). 2. Geologic site reconnaissance. 3. Evaluation of seismic design parameters. 4. Engineering and geologic analysis of data collected. 5. Preparation of this report and accompaniments. SITE DESGFiiPTtON AND PROPOSED CONSTRUCTION The subject property is a irregularly-shaped parcel, approximately % acre In size, bounded by Jefferson Street on the east, an adjacent residential property to the south, and a condominium complex to the north. Open space assoclatec! with the Buena Vista Lagoon areabounds the western sideof the property (Figure 1, Site LocationMap). The property Base Map: TOPOl® ©2003 National Geo^aphic, U,S.G.S. San Luis Rey Quadrangle, Califorraa San Diego Co., 7.5 Minute, dated 1^7, current 1999. 2200 440^ Base Map: The Thomas Guide, San Diego County, Street Guode and Directory, 2008 Edition, by Thomas Bros. Maps, page tI06. Raprodueod wtih permfs*'©" gronted by thofno* Bros. Maps This mop is copyrighted by Thomos Bros. Map». H is unlowlul to popy or rBpcoctUco Olt Of any port ihoraai, whoiiier for ptsrsonal Lise or resale, wttlvout pfirmission. AIf rights reserved. IM W.O. 5701-A-SC SITE LOCATION MAP Rgire 1 itself consists of a relatively level pad area adjacent to Jefferson Street, and a large natural slope which descends approximately 50 to 55 feet westward from the pad area to Buena Vista Lagoon. Between the pad elevation of approximately 65 feet Mean Sea Level (MSL) and an elevation of approximately 25 feet MSL, the slope descends at an approximate gradient of 272:1 (horizontahvertical [h:v]). From an elevation of 25 feet MSL to the lagoon level, the slope flattens to a gradient of approximately AVz.l (h;v). Several small 3- to 5-foot wide hand cut (?) terraces are present in the upper portion of the slope. Existing improvements to the property consist of remnants of an old foundation system (retaining walls and concrete slab) located in the upper portion of the existing pad area near Jefferson Street. Vegetation on the property in the vicinity of the jsad area consists of some srrrall trees and scattered grasses. Vegetation on the slope consists of primarily grasses. Drainage wtthin the property is predominately by sheet flow directed toward Jefferson Street, or down the slope face toward Biiena Vista Lagoon. It is our understandHig that the proposed develo would consist of preparing the site for the constmction of a mutli-story, split-level residential structure to be built into the existing hillside (BGI, 2008). Gut and fill grading techniques are anticipated to be utilized to construct the building pad. A review of BGI (S008) indicates predominantly cut excavation. Lessor backfills behind various retaining walls are also anti A site plan showing the limits of the planned structure Is included in this report as Plate 1. Plate 1 uses the site plan for the project, prepared by the BGI (2008), as a base. Plans indicate a main floor (street level) with an upper floor above the main floor, and a lower floor, located below the western portion of the main floor. Foundations are anticipated to utilize continuous/spread foofings for support. Concrete slab on grade are plannedfor the lower level guest room and the main floor garage slab. All otherfloor areas appear to utrlize raised wood flooring systems. Building loads are unknown at this time but are assumed typical for this type of relatively light construction, and appear to vary from one to two floor loads across the structure. Sewage disposal is to be accommodated by tying into the regional munidpal system. PREVIOUS WORK A preliminary geotechnical study was performed for the site by GSl in 1993 (GSI, 1993). This study evaluated the site based on the industry standards at that time, and provided earthwork and foundation design construction recommendations for the proposed structure. Following the completion ofthe preliminary report, an additional update report was completed in 2003 (GSI, 2003). This study was also based on the industry standards at thattime, and provided earthwork and foundation design construetion recommendations for the proposed structure. Mr.TedHagey^ " W:0.5701^ Jefferson Street. Carlsbad June 17 2008 Fite:e;\wp9\57G0\5701a.upg ' p.^^^ g Ge&Soits. Inc. EARTH MATERIALS A review of GSl (1993 and 2004) indicate that formational soils underiying the site consist of Quaternary-age terrace deposits (silty sand [SM]), underiain at depth by sedimentary bedrock (silty to clayey sandstone [SM-SC]) belonging to the Eocene-age Santiago Formation. Surficial "native" deposits of colluvium and older alluvium are also present onsite, as well as localized, surficial deposits of undocumented fill. An in-depth discussion of site soils is presented in GSl (2003). Based on our review of BGI (2008), the contact between terrace deposits (Map Symbol Qt) and the Santiago Fonnation (Map Symbol Tsa) will be encountered during site excavation (see Plate l). GROUNDWATER Groundwater was encountered in preparation of GSI (1993 and 2003). Perohed water tables (seepage) were noted slightly beneath the contact between terrace deposits and the underiying Sahtiago Formatipn (i.e., approximately 18 to 19 feet below the main floor elevation, MSL = 49 feet), and at depths of 34 feet (MSL - 31 feet) beiow the main floor elevation. The regional groundwater table was apparently encountered at a depth of 52 feet (MSL = 13 feet), where water levels appear to coincide with the groundwater gradient to the adjaeent coasta! lagoon. Seepage may occur locally (due to heavy precipitation or irrigation) in areas where relatively permeable soils overiie relatively impemieable soils or bedrock. Such materials may be encountered in the earth units that exist onsite. Thus, this potential for perched groundwater is signiflcant on the subject site, both during and after development and this potential should be disclosed to all Interested/afl'eGted parttes. Perched groundwater conditions along fill/bedrock contacts, and along zones of contrasting permeabilities, should not be precluded from occurringin the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated especially where seepage near the terrace/bedrock contact occurs at a depth of approximately 18 to 19 feet (MSL - 46 to 47 feet). Should perched groundwater conditions develop elsewhere, this office could assessthe affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions Again this should be disclosed to the owner of the facility and all interested/affected parties' Recommendations for the mitigation of anticipated perched groundwater conditions are presented in a later section of this report. SEISMIC DESIGN PARAMETERS Based on the site Gonditions, and Chapter 16 of the Uniform Building Code/California Building Code (fUBC/CBG|, International Conferenee of Building Officials [ICBO], 1997; Mr. Ted Hagey ~- "~~WO 5701-A-SC Jefterson Street, Carlsbad June 17. 2008 File;e:\wp9\5700\570ta,upg p^^^ ^ CalHbmlaBuildihg standards ComniissiDnlCBSC^ provided in the Iollowing tables: 1997 UBC/CBC fcHAPTER 16 SEISMIC PARAMETERS Seismic Zone (per Figure 16-2*) 4 Seismic Zone Factor (per Table 16-1*) O.'IO Soil Profile Type (per Table t6-J*) Sp Seismic Coefficient C^ (per Table 16-Q*) 0,44N^ Seismic Coefficient C^ (per Table 16-R*) 0.64N^ Near Source Factor (per Table 16-S*) 1.0 Near Source Factor (per Table 16-T*) 1.0 Distance to Seismic vSource 6.6 mi (10.6 km) Seismic Source Type (per Table 16-U*) B Upper Bound Earthquake (Rose Canyon fault) M„ 6.9 PHSA (10 percent probabilitv of exceedance in 50 years) 0.25q * Figure and Tablo references trom Chapter 16 of the UBC/CBC (ICBO 1997- CBSC 2007) The table below summarizes the site-specific design criteria obtained from the 2007 CBC We used the computer program Seismic Hazard Cu wes and Uniform Hazard Response Spectra, provided by the U.S.G.S. The short spectral response uses a period of 0.2 seconds. CBC SEISMIC DESIGN PARAMETERS PARAMETER VALUE IBC-06 REFERENCE Site Class D Table 1613.5.2 Spectral Response - (0.2 sec), S, 1.165g Figure 1613.5(3) Spectral Response - (1 sec), S, 0.441 g Figure 1613.5(4) Site Coefficient, F, 1.034 Table 1613.5.3(1) Site Coefficient, F^ 1.6 Table 1613.5.3(2) Maximum Considered Earthquake Spectral Response Acceleration (0.2 see), Sj^ 1.20Sg Section 1613.5.3 (Eqn 16-37) Maximum Considered Earthquake Spectral Response Acceleration (1 sec), S^, 0.687g Section 1613.5.3 (Eqn 16-38) 5% Damped Design Spectral Response Acceleration (0.2 sec), S^s o.eosg Section 1613.5.4 (Eqn 16-39) 5% Damped Desigri Spectral Response Accelemtion (1 sec), Sm 0.458g Section 1613.5.4 (Eqn 16-40) Mr. Ted Hagey Jefferson Street, Carlsbad File;e:\wp9\5700\5701 a.upg W.O. 5701-A-SC June 17,2008 Page 5 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 proiect life, not to eliminate all damage, since such design may be economically prohibitive. Cumulative effects of seismic events are not Included In the code and regular maintenance and repair following significant seismic events (i.e., M„4.5, or greater) will likely be necessary. PRELIMiMARY CQNGLIJSIONS AND RgCOMMENDATIOWS General Based on our previous field exploration, laboratory testing (GSl, 1993 and 2003), and our engineering and geologic analyses, it is our opinion that the p the proposed use from a soils engineering and geologic viewpoint, provided that the recommendations presented herein are incorporated into the design and oonstruction phases of site development. The primary geotechnical concerns with respect to the proposed devetopmerrt are: Earth materials characteristics and depth to competent bearing material depth of foundations, etc. On-going expansion and corrosion potential of site soils. Subsurface water and potential fbr perched waterto occur during grading and after development. Slope stabilrty, including temporary slope stability during construction. Non-slruotural zone on unmitigated perimeter conditions (proposed Improvements subject to distress). Regional seismic activity. The recommendations presented herein, and in GSI (1993 and 2003), consider these as well as other aspects of the site. The engineering analyses performed concerning site preparation and the recommendations presented herein have been completed using the information provided and obtained during our field work. In the event that any significant changes are made to proposed site development the conclusionsand recommendations contained in this report shall not be considered valid unless the changes are reviewed and the recommendations of this report evaluated 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. Mr^ Ted Hagey ^ - wK^rAlic Jefferson Street. Carlsbad j^^^ Rle:e:\wp9»70ClV5701a,upg p^^^ g Gm@Smt§, lme. EARTHWORK CONSTRUCTION RECOMiWENDATIONS All gradirig should conform to me guidelines presented in the UBC/CBC (ICBO 1997- CBSC, 2007), the requirements of the C|ty, and as Indicated in GSI (2003). f^rior to grading, a GSI representative should be present at the preconstruction meeting to provide addrtional grading guidelines, if needed, and review the earthwork schedule During earthwori< construction, all site preparation and the general grading procedures ofthe contractor should be observed and the fill selectively tested by a representative(s) of GSI If unusual or unexpected condlttons are exposed in the field, they should be reviewed by this oflice and, if warranted, nriodified and/or additionat recommendations will be offered All applicable requirements of local arid nalionaf orders, the Oocupational Safety and Health Act (CamSHA), and the Consti-uction Safety Act should be met J While not grading plans, site plans (BGI, 2008) and Plate 1 generally indicate cut excavation to attain the desired graded configurations. Excavation in the vicinity of the "lower terrace" and "guest room" may expose unsuitable soils near pad grade as pad grade "daylights" at the natural slope. In these areas, deepened footings may be necessary to penetrate unsuitable near-surface soils, and/or remedial grading to remove and recompact any unsuitable soil beneath slabs/foundations may be performed. General earthworic and grading guidelines, and preliminary criteria, are provided in Appendix B Subdrainage to control seepage from along bedding/formationat contacts exposed during grading/excavation will likely be recommended, and should be anticipated Subdrainage will likely consist of "burrito" type gravel drains placed on backcut benches and at appropnate elevations, during grading/wall construction. General construction guidelines for drains are included in the retaining walls section of this report. The ultimate location of drain(s) will be based on conditions exposed during grading/excavation operations. TEMPORARY CONSTRUCTION SLOPES Temporary cuts for wall construction should be constructed at a gradient of V^: 1, or flatter for slopes exposing sedimentary bedrock to a maximum height of 20 feet per Cal-QSHA for Type A soils, assuj33iDgjTo_gjmiD^^ Temporar/ cuts should be constructed at a gradient of 1:1 (h:v), or flatter, for slopes exposing existing fill, per Cal-OSHA for Type B soils, again, assuming no groundwater. If groundwater is encountered construction should be stopped until the geotechnical consultant has analyzed this condition and amends these recommendations, in writing. Construction materials and/or stockpiled soil should not be stored within 5 feet of the top of any temporary slope Temporary/permanentprovisions should be made to direct any potential runoff away from the top of temporary slopes. Temporary slopes should be evaluated during construction by the geotechnical engineer for any comments, or revisions to this recommendation Removals and/or temporary cuts should be made with sufficient space to allow for subdrains and/or wall back drains as recommended. Mr. Ted Hagey ^ Wo'sfm-k^ Jefferson Street. Carlsbad ""^^^ r-i!e:e:\wp9\5700\570ta.upg ^ •* Page 7 C«#S«Hs, Inc. PRELIMINARY FOUNDATION REGOMMENDATiONS Qeneral Based on our review, the foundation design and construction recommendations presented in GSl (2003) generally remain valid and applicable, unless specifically superceded in the text ofthis report. The preliminary foundation design and construction recommendations are based on laboratory testing and engineering analysis of onsite earth materials by GSl. In the event tiiat the information concerning the proposed development plan is not correct or any changes in the design, location, or loading conditions of the proposed sti-uctures 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. Foundation designers should consider the following Infomnation as minimums, ft-om a geotechnical standpoint, and meet the minimum design criteria provided in the UBC/CBC (ICBO, 1997; CBSC, 2007) to reduce the potential for on-going adverse effects of expansive and/or corrosive soils. As indicated, the information and recommendations presented In this section are considered minimums and are not meant to supercede design(s) by the project structural engineer or civil engineer specializing in structural design. Upon request. GSI could provide additional consultation regarding soil parameters, as related to foundation design. Soii Expansion Potential and Foundation Design Based on a review of GSl (1993 and 2003) site soils are considered to be very low expansive. However, the presence of higher expansive soils cannot be precluded at this time and wll need to be re-evaluated during site grading/excavation. The foundation design and construction recommendations are based on prior laboratory testing and engineering analysis of onsite earth materials by GSI. Recommendations for foundation systems are provided in the following sections. The foundation systems may be used to support the proposed structure, provided they are founded in competent bearing material. The proposed foundation systems should be designed and constructed in accordance with the guidelines contained in the UBC/CBC (ICBO, 1997; CBSC, 2007). The following foundation construction recommendations are presented as a minimum criteria from a soils engineering viewpoint. The onsite soils expansion potentials generally appear to range from very low (E.l. = 0 to 20) range to medium (E.l. = 51 to 90). For very low to low expansive soils with a P.l. less than 15, conventional foundation design and construction may be used. For low to medium expansive soils (E.l. = 21 to 90) with a P.l. greater than 15, foundation design/construction in consideration of expansive soils are recommended (i.e., post-tension, welded wire/post-tensron method) in accordance with the UBC/CBC (ICBO, 1997; CBSC, 2007), Section 1815 and/or 1816.' Recommendations by the project's design-structural engineer or architect, which may exceed the soils engineer's recommendations, should take precedence over the foilowing Jefferson Street, Carlsbad 2008 File:e;\wp9\570O\57O1 a.upg Page B 0«###fls5 Ine, minimum requirements. Final foundation design will l>e provided based on the expansion potential of the near-surface soils encountered during grading and/or the depths SOIL MOISTURE CONSiDERATIONS GSI has evaluated the potential for vapor or water transmission through any new slab in light of typical floor coverings and Improvements. Please note that generally slab moisture emission rates range fronn about 2 to 27 lbs/24 hours/1,000 square feet from a typical slab (Kanare, 2005), while floor covering manufacturers generally recommend about 3 lbs/24 hours as an upper linnit. Thus, theClient will need to evaluate the following in light of a cost V. benefit analysis (owner complaints and repairs/replacement) along with disclosure to interested/affected parties. Considering the anticipated typical water vapor ti-ansmission rates, floor coverings and improvements (to be chosen by the Client) that can tolerate those rates without distress, the fol lowing alternatives are provided: Slabs should be a minimum of 5 inches thick. Concrete slab underiayment should consist of a 10-mil to 15-mil vapor retarder or equivalent, with alt laps sealed per the UBC/CBC (ICBO, 1997; CBSC, 2007) and the manufacturer's recommendation. The vapor retarder should comply with the ASTM E 1745 - Class A or B criteria, and be Installed in accordance with ACI 302.1 R-04. The 10- to 15-mit vapor retarder (ASTM E 1745 - Class A or B) shal! be installed per the recommendations of the manufacturer, including aR penetrations (i.e.. pipe, ducting, rebar, etc.). The vapor retarder may foe placed near the mid-point of a 4-inch thick layer of clean sand (S.E. >30), placed over properly compacted subgrade soil. Concrete should have a maximum water/cement ratio of 0.50. This does not supercede Table 19^-4 of the UBC/CBC (ICBO, 1997; 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. 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 thatthe concrete used in the foundation and slabs are designed and/or treated for more uniform moisture protection. Mr^Ted Hagey " —~ W.O. 5701-A-SC Jefferson Street, Carlsbad June 17 2008 Fiie:e:\wp9\5700\5?01a.upg p^g^ g Ge&S&iis^ lme. Theowner(g should be specifically adwsed which areas are suitable for tile flooring, wood flooring. Or other types of waterArapor-sensrtive flooring and which are not suitable. In all planned floor areas, flooring shall be installed per the manufactures recommendations. Additional recommendations regarding water or vapor transmission should be provided by the architect/sti^uctural engineer/slab or foundation designer and should be consistent with the specified floor coverings indicated by the architect. Regardless ofthe mitigation, some limited moisture/moisture vapor transmission tiirough 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 tiie flooring contractor should reviewthe slab and moisture retarder plans and provide comment prior to the construction of the foundations or improvements. The vapor retarder contractor should have representatives onsite during the initial installation. PRELIMINARY WALL DESIGN PARAMETERS Conventionaf Retaining Walls the design pararneters provided below assume that eittiM rion-expansive soils (typically Glass 2 permeable filter material or Class 3 aggregate base) or native onsite materials (up to and including an E.l. 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 cleariy shown on the plans. Building walls, below grade, 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 report, as appropriate. Footings should be embedded a niinimum of 18 inches below adjacent grade (excluding landscape layer 6 inches) and should be 24 inches in width. If retaining walls are proposed in planted areas, they should be deepened to 24inches (excluding the top 6 inches). There should be no increase in bearing for footing width. Recommendationsfor specialty Walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. For walls that are part of the building sfi-ucture, wall backfill should be compacted to at least 95 percent relative compaction if wall footing are founded in formational soii. Restrained Walls Any retaining walls that will be restrained priorto 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 surctrarge loading. Mr TedH^ey " - W.O. 5701-A-SC Jefferson Street, Carlsbad j^^^^ ^ ^ ^^^3 Fite;e:\wp9\5700\57O1 a.upg Page 10 Ge&S&itSf Ine. For areas of male or re-entrant comers, the resti^ined wall design should extend a minimum distance of twice the height of the wall (2H) laterally ft-om the comer For walls that are part of the building stiucture, wall backfill should be compacted to at least 95 percent relative compaction If waJ! footing are foundedin formational soil. Cantilevered Waits The recommendations preserited below are ft>r cantilevered retaining walls up to 10 feet high. Design parametefs 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, providedthetop of the wall is notresti-ained firom 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 speciflc 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 conditionsfGrsuperimpOsed loads can be provided upon request. For walls that are part of the building stmcture, wall backfill should be compacted to at least 95 percent relative compaction if wall footing are founded in formational soil. SURFACE SLOPE OF RETAINED MATERIAL (HORIZONTAL: VERTICAL) EQUIVALENT FLUID WEIGHT P.C.F. (SELECT BACKFILL)** EQUIVALENT FLUID WEIGHT P.C.F. (NATIVE PRE-APPROVED BACKFILL)*** Level* 3 to 1 38 55 45 60 * Level backfill befiind a retaining wall is defined as compacted earth materials properlv drained, without a slope for a distance of 2H behind the wall. ** E.l.<20, PJ.<15, SE>30, <10% passing No. 200 Sieve. ***E.I.<50, P l.<T5, SE>25. <15% passinq No. 200 Sieve Retaining Wall Backfill and Drainage For walls that are part of the building structure, wall backfill should be compacted to at least 95 percent relative compaction if wall footing arefounded in formational soil. Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabricand 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 %-inch to r/a-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 vvalls and upward at least 1 foot. For native backfill that has up to an E.l. of 50, continuous Mr. Ted Hagey Jefferson Street. Carlsbad nie:e;\wp9\5700V5701 a.upg W.O. 5701-A-SC June 17, 2008 Page 11 (1) Waterproofrig merrlbrane CMU or reinforced-concrete wall Siructiral foofing or settlement-sensitive improvement —^ Provide surface drainage via an engineered V-ditch (see dwl plans for details) p Proposed grade ^ sloped to drain \ per precise eivi drawings (5) Weep hole Footing and wall design by others Native backtiil 1=1 (h:v) or flatter backcut to be properly benched (6) Footing (1) Waterproofing membrane. (2) Gravet- Ctean, crushed, % to inch. (3) Filter fabric: Mirafi 140N or approved equivalent (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient sloped to suitable, approved outlet point (perforattons down). (5) Weep hole: Minimum 2-inch diameter placed at 20-foof centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe ol wait No weep holes for below-grade walls. (6) Footing: if bench ia created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additionat "heel" drain wi likely be required by geotechnical consultant. RETAINING WALL DETAIL - ALTERNATIVE A Detail 1 (1) Waterproofing membrane (optional) CMU or reinforced-concrete wall Structural footing or settlernent-sensith/e improvement Provide surface drainage via engineered V-ditch (see civil plan details) (5) Weep hole — Proposed grade ^ j sloped to drain / per precise civil j drawings Footing and wall design by others Native baekfiB n (h:v) or flatter backcut to be properly benched ~^ (6) 1 cubic foot of %-inch crushed rock — (7) Foofing (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 equivalent for waterproofed walls (al! perforations down). (3) Filter 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-foGt 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, % to iKi inch. (7) Footing: If bench is created behind the footing greater than the foofing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. RETAINING WALL DETAIL - ALTERNATIVE B Detail 2 (1) Waterproofing membrane CMU or reinforced-concrete wall Structural footing or settlement-sensitive improvement " Provide surface drainage ^ 21 (h:v) slope Footing and wall design by others (5) Weep hole Proposed grade \ sloped to drain per precise civil drawings (3) Filter fabric (2) Gravel " (4) Pipe (7) Footing - (8) Native backfill (6) Clean sand backfill 1:1 (h:v) or flatter backcut to be properly benched (1) Waterproofing membrane: Liquid boot or approved masticequivalent. (2) Gravel: clean, crushed, % to % inch. (3) Filter fabric: yirafi 140N or approved equivalent. (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outiet point (perforations down). (5) Weep hole: Minimum 2-ineh diameter placed at 20-foot centers along the wall and placed 3 inches above finished surtace. Design civil engineer to provide drainage at toe of wait No weep holes for below-grade walls. (6) Clean sand baekfi: 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 El. <21 and S.E. )35 then aB sand requirements also may not be required and will be reviewed by the geotechnical consultant. RETAINING WALL DETAIL - ALTERNATIVE C Oetail 3 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 Wail Backfill and Subdrain Detail Geotextile Drain). Materials with an E.l. 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). Outlets should consist of a 4-inGh diameter solid PVC or ABS pipe spaced no greater than ± t oo feet apart, with a minimum of two outiets, 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.l. <.50). Proper surtace 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. Wali/Retainina Wait Footing TransiMons 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), thon the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. Mr Ted Hagey ~" WO. 5701-A-SC Jefferson Street, Carlsbad June 17 2008 R!e;e:\wp9V5700\5701 a.upg Page 15 0e#S#f ls, Ine, DEVELOPigiENT CRITFRIA Slope Defdrnmation 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 difl^erential vertical heave or settlement in combination with differential lateral movement in the out-of-slope directton, after grading This post-eonstniction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Step@creep is caused by alternate w&mng and diylng ofthe fill soils which results in slow downslope movement. ThistypeofmovementfsexpeGtedtooccurthroughoutthe life of the slope, and is anticipated to potentially affect improvements or structures (e g separations and/or craeking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet fi'om 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^erm 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 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 stmctural 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 homeowners association or other interested/affected parties. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials Slope stability IS significantly reduced by overiy 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 adversely affects site Improvements, and causes perched groundwater conditions Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be minimizedand surficial slope stability enhanced by establishing and maintaininga 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 l«r Ted Hagey ^^"^ Wai^^rSC Jefferson Street, Carlsbad j,^^^ ^ 2008 File:e;\vvp9\5700\57O1 a.upg p^^^^ CeoSoitSj Inc, 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 shouid be implemented Irngation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to the homeowners association or other interested/affected parties. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate tot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and stopes. Surface drainage should be sufficientto preventponding of water anywhere on a lot, and especially nearstmctures 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 ftiture landscaping or construction activities do not create adverse drainage conditions Positive site drainage within tots 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 stmcture. 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 dralnagedevices 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 irngation 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? Jefferson Street, Garlsbad j^^g 2008 Rfe:e:\wp9\5700\570'ta.upg ' p^gg -^j GemSmiiSf ine. 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.)? Are there cut-fill ti-ansitions (i.e., fill over bedrOck), within the slope? 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? Noriih 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 10 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 lot or a lot where perched or ponded water may adversely impact its proposed use? Based on these general criteria, the constructton of toe drains may be considered by the design engineer along the toe of slopes, or at retaining wails 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 eonditions, owner irrigation, or other circumstances. Where drains are constructed during grading, including subdrains, the locations/elevations of such drains should be sun/eyed and recorded on the final as-built grading plans by the design engineer It is recommended that the above be disclosed to any affected/interested parties including homeowners association or other interested/affected parties. Erosion Control Cut and fill slopes will be subjectto surficial erosion during and after grading. Onsite earth rnaterials 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 Detail structures be eliminated for a minimum distance of 10 feet. As an altemative Mr. Ted Hagey Jefferson Street. Carlsbad File:e;\wp9\5700\5701 a.upg W.O. 5701-A-SC June 17,2008 Page 18 M (FW) slc^e (typicaD BaeWl with cOrr|jacted native soils Top of waill Retalnirg wall Finish grade Wall footing Mirafi 140 filter fabric or equivalent %-inch crushed gravel 4-inch drain 1to2fee»- NOTES: 1 Soii cap compacted to 90 percent relative compaction. 2. Permeable material may be gravel wrap^d in filter fabric (Mirafi MON or equivalent). 3. 4-Tnch-diameter, perforated pipe (SDR-35 or equivalent) with perforations down. 4. Pipe to maintain a minimum 1 percent fait 5. Concrete cut-off wall to be provided at transifion to solid outlet pipe. 6. Solid outlet pipe to drain to approved area. 7. Cleanouts are recommended at each property line. 8. Effort to compact shouid be applied to drain rock. SUBDRAIN ALONG RETAINING WALL DETAIL Detail 5 Drain pipe Native soil ' . cap Permeable material —-- •12 inchea- — Drain may be eonstruGted into, or at, the toe-of-slope 12-mch minknum 24~rich minimutn 1 1. 2. 3. 4. 5. 6. Z Soil cap corapacted to 90 percent relative compaction. Permeable material may be gravel wrapped in filter fabrie (Mirafi 140N or equivalent). 4-inch-diameter, perforated pipe (SDR-35 or equivalent) with perforations down. Pipe to maintain a minimum 1 percent fall Concrete cut-off wall to be provided at transition to solid outlet pipe. Solid outlet pipe to drain to approved area. Cleanouts are recommended at each property line. SCHEMATIC TOE DRAIN DETAIL Detail 4 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 tiie "Drainage" section, the installation of gutters and downspouts should be considered to collect roof water that may othenwise 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 cany the water away from the building, 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 tiiat the recommendations contained in this report are incorporated Into final design and constnjction 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 fijture due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assessthe 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 ftjture. 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 Dot be constructed without specific design and construction recommendations from Mr. Ted Hagey ~ WoTsmPArSC Jefferson Street, Carlsbad June 17 2008 Fi!e:e:\wp9\£j700\5701 a.upg Page 21 GmmSmts^ ime. GSl, and this construction recommendation should be provided to the homeowners association or other interested/affected parties. This office should be notified in advance of any fill placement, grading ofthe site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench and retaining wall backfills flatwork etc. Tiie Flooring Tiie 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 offiGe 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 obsen/ed by a representative ofthis 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 ofthe 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 Ailexcavations should be obsen/ed by an engineering geologistor soil engineer from GSI prior to workers entering the excavation or trench, and minimally conform to Cal-OSHA' state, and local safety codes. Assuming no groundwatGr,;"Type B" soils may be assumed' Mr^ Ted Hagey '^Wom:^ Jefferson Street, Cartsbad j^,,,^ 2008 File:e:\v/p9\5700\5701a.upg . Page 22 Gm&SmttSf Imc, Should adverse conditions exist, appropriMe recornrnendations would be oflered at that time. The above recommendations should be provided to any contractors and/or subcontractors, or homeowners association or other interested/affected parties, etc.. that may perform such work. Utilitv Trencii Bacitfiii 1. All interior utility trench backfill shouW be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relati^ compactfon of 90 percent ofthe laboratory standard. As an afternative for shallow (12-Inch to 18-inGh) under-slab trenches, sand having an S.E. value of 30. or greater, may be utilized and jetted or flooded into place. Obsewation, probing and testing shou ld be provided to evaluate the desired resu Its. 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 nol 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 footingor grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations ofthe structural engineer. SUrVliVIARY 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 freestanding walls footings, prior to the placement of reinforcing steel or concrete. Mr Ted Hagey Vm^TOlXsC Jefferson Street, Cartsbad June 17 2008 Rle:eAvn)9\5700\570la.Upg Page 23 GeoSoils, ine. Prior to pouring any slabs or flatworic. after presoaking/presaturation of buikjing; 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 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 ofthis report. Whenany improvements, such as flatwork, spas, pools, walls, etc., are constructed , prior to Gonstruction A report of geotechnical obsen/ation and testing should be provided at the conclusion of each of the above stages. In order to provide concise and clear documentation of site WQri<, and/or to comply with code requirements. GSI should review documents to homeowners associations or other interested/affected parties for geotechnical aspects, including inigation practices, the conditlons outlined above, etc.. prior to any sales. At that stage, GSl will provide 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-structureinteraction and consider, as needed, bearing, expansive soil influence, and strength, stiffness ahd deflections in the various slab, foundation, and other elements in order to develop appropriate, design-specific details. As conditionsdictate, 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, ff 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. Ted Hagey '~lra~57oi'Xsc Jefferson street, Carlsbad June 17 2008 File;e:wp9\S7dO\.<>701a.upg p^gg 24 Inc. tiiat some. mOre restrictive details will be required. If the stmctural engineer/designer has any questions or requires ftJrther assistance, they should not hesitate to call or othenwise transmit their requests to GSl. In orderto mitigate potential distress, the foundation and/or improvement's designer should confimn to GSI and the governing agency, in writing, that the proposed foundations and/or improvements can tolerate tiie amount of differential settlement and/or expansfon characteristics and design criteria specified herein. PLANREVtEW Final project plans (grading, precise grading, foundation, retainlngwall, landscaping, etc.), should be reviewed by this office prior to construction, so that construction' is iri accordance with the conclusions and reeommendations 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, either express or implied, is given. Standards of practice are subject to change with time! GSl assumes no responsibility or liability for work or testing performed by others, or their inaction; or wori< 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 tiie 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. Ted Hagey ""WOITOIXSC Jefferson Street, Garlsbad 2003 Fi(e:e-.\wp9\5700©701a.upg p^^^ 25 # The opportunity to be of sen/ice is sincerely appreGlated. If you should have any questions, please do not hesitate to contact our olfflee. Respectftjlly submitt GeoSoils, Inc. Robert G. Crisman Engineering Geologis! David W. Skelly Civil Engineer, RCE 47857 RGC/DWSAJPF/jk Atta;Ghments: Distribution: Appendix A - References Appendix B - Grading Guidelines Plate 1 - Geotechnical Map (4) Addressee Mr. Ted Hagey Jefferson Street, Carlsbad Fite:e:\wp9\S700V5701 a.upg W.O. 5701-A-SC June 17,2008 Page 26 G-e@SoiM^ ine. APPENDIX A REFERENCES APPENDIX REFERENCES ACI Comrnlttee 302.2004, Guide for concrete floor and slab construction , AGl 302.1 R-04, dated June. ASTM E 1745-97,2004. Standard specilcation for water vapor retarders used in contact with soil or granular fill under concrete slabs. Beery Group, Inc.. 2008, Site plan: Hagey residence, Jefferson Street, Carlsbad, Ca., Sheet C-1, Job no. 2610, dated 2008. Califomia Building Standards Commission, 2007. California buifoling code. GeoSoils. Inc., 2003, Preliminary geotechnical evaluation, APNs 155-140-37 and 155-140-38, City of Carisbad , San Dlego County, California, W.O. 3213-A-SC. dated September 18. ^ 993, Preliminary geotechnical evaluation, Parcel 155-140-09, Carlsbad Calrfornia W.O. 1624-SD, dated November s International Conference of Building Officials, 1997. Uniform building code: Whittier, California, International conference of building officials, Volumes 1, 2. and 3. Kanare. Howard, M.. 2005, Concrete floors and moisture. Engineering Bulletin 119, Portland Cement Association. State of California, 2008, Civil Code, Sections 896-897. Ge&S&it$^ Inc. APPENDIX B GRADING GUIDEUNES GiLNERAL EARTHWORK, GRADING GUiDELiNES. AND PRELIMINARY CRiTERIA General These guidelines presentgeneralprocedures and requirem^^ 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 wouldsupercede the provislonsGontained hereafter in the case of conflict. Evaluations performed by the consultant during tiie 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. Thecgntractor is responsibte for the satisfactory completion of all earthwork in accordance withprovisionsoftheprojectplansandspecifiGatlonsandlatestadoptedcode. Inthecase of conflict, the most onerous provisions shall prevail. The project geotechnical engineer and engineering geologist (geotechnicalconsultant), and/or their representatives, should provide obsen/ation and testing sen/ices, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnicai consultant (soil engineer and engineering geologist) should be employed forthe purpose of obsen/ing earthwork procedures and testing the fills for general conformance with the recommendations of the geotechmcal report(s), the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and obsen/ation so that an evaluation may be made that the work Is being accomplished as specified, ft 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 fifl, key excavations and subdrain Installation should be observed and documented by the geotechnical consultant prior to placing any fill. It is the contractor's responsibifity to notify the geotechnical consultant when such areas are ready for obsen/ation. Laboratory and Field Tests Maximum dry density tests to detemiine the degree of compaction should be performed in aecordance with American Standard Testing Materials test method ASTM designation D-1557. Random or representative field compaction tests should be performed in GmoSmiiMf Inc, accordance with test methods ASTM designation D-1556, D-2937 or D-2922, and D-3017, at inten/als 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 Hie discretion of the geotechnical consultant. Contractor's Responsibility All clearing, site preparatton. and earthwork performed on the project should be conducted by the contractor, with obsen/ation by a geotechnlcal consultant, and staged approval by the governtng agencies, as applicable, ft is tiie contractor's responsibility to prepare the ground surface to receive thefill, tothe satisfaction of the geotechnical consultant, and to place, spread, moisture condition, mix, and compact the fill in accordance vvith the recommendations of the geotechnical consutent The contractor should also remove all non-earth material considered unsatisfactory by the geotechnical consultant. Notwithstanding the sen/ices provided by the geotechmcal consultant, it is the sole responsibility ofthe confi-actor 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 ttie geotechnical consultant, unsatisfectory conditions such as questionable weather, excessive oversized rock or deleterious material, insufficient su pport 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 instaiied. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material, shouid be removed and disposed of off-site. These removals must be concluded priorto placing fill. In-place existing fill, soil, alluvium, colluvium, or rock materials, as evaluated by the geotechnical consultant as being unsuitable, should be removed priorto 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. Mr. Ted Hagey AppendbTe File: e:\5700\5701.upg Page 2 GeoS&ils^ lme. m Any underground stmctures such as cesspools, cisterns, mining shaffe, 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 consultanL Soft, dry, spongy, highly fractured, or otherwise unsuitable ground, extending to such a depth that surface priseessing cannot adequately improve the condttion, should be overexcaMed down to firm ground and approved by the geotechnical consultant before compaction and filling operations continue. Overexcavated and processed soils, which have been properiy 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) toa 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 greaterthan 6 to 8 Inches in depth, it may be necessary to remove the excess and place the material in llfte 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 the 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 minimum 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 bythe geotechnical consultant. As a general rule, unless specifically recommended othenfl/ise bythe geotechnical consultant, the minimum width of fill keys should be equal to % 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 obsen/ed and approved by the geotechnical consultant prior to placement of fill. Fills may then be properiy placed and compacted until design grades (elevations) are attained. f^lr. Ted Hagey "Appendix B Fiie: e:\5700\5701. upg pgqg 3 GeoSoiiSj imc. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each materiai 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, undesitable expansion potential, or substandard sfrength characteristics may be designated by the consultant as urisultable and may require blending with other soils to serve as a satisfactor/fifl 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 fi 11/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 bythe geotechnical consultant. Oversized material should be taken offsite, or placed In accordance with recommendations ofthe geotechnical consultant in areas designated as suitable for rock disposal. GSl 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 operationson 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 ornatural 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 Ihis report. The goveming agency may require that these materials need to be deeper, crushed, or reduced to less than 1 ? inches in maximum dimension, at their discretion. ; To facilitate future trenching, rock (or oversized material), should not be placed Within the hold-down depth feet from finish grade, the range of foundation 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 laborator/ by the geotechnical consultant to evaluate it's physical properties and suitability for use onsite. Such testing Mr. Ted Hagey Appendix B File: e:\5700\570l.upg - Page 4 Ge&Soiis^ tt$e. should be performed three (3) days prior to importation. If any material other than that previously tested is encountered during grading, an appropriate analysis ofthis 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 unlfomiity of material and moisture suitablefor 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 conditioning, blending, and mixing of the m layer shouid 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 Otiienvise recommended by the geotechnical consultanL Compaction equipment shouldbeadequatelysized and should be specifically designed for soil compaction, or of proven reliability to efficiently achieve tiie 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 fil! 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 ofthe California Building Code (CBC), fill slopes should be designed and constructed at a gradient of 2:1 (h:v), orfiatter. Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequentiy 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 speeified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing toose matenals with appropriate equipmenL A final evaluation of fill slope compaction should be based on obsen/ation 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. Mr. Ted Hagey - - A^^^^ File: e:\5700\5701.upg '^'^ p^^^ ^ GeoB&Us^ Ine, 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 10 feet of each lift of fill by underi^aking 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 overtiie slOpeto 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 inten/als, 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 Gompaction, 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 thto 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 tiie geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical consultant. The geotechnical consuttant may recommend and direct changes in subdrain line, grade, md drain material in the field, ponding exposed condftions. The location of consfructed subdrains, especially the outlets, should be recorded/sun/eyed 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 overexcavationand refilling of cut areas should be performed, and/or remedial grading of Mr. Ted Hag^^ ' " ^ Appe^^dbTi File: n:\5700\5701.upg Page 6 GeeS&it^^ Ine, cut slopes should be performed. When fill-over-cut slopes are to be graded, unless othenwise approved, the cut portion ofthe slope should be obsen/ed by the geotechnical consultant prior to placement of materials for construction of the fill portion of the slope. The geotechnical consultant should obsen/e 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 OthenA/ise specified in geotechnical and geofogical report(s). no cut slopes should be excavated higher or steeper than that allowed by tiie ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractor's responsibility. Erosion control and drainagedevices should be designed by theproject civil engineer and should be constructed in compliaice with the ordinances of the controlling governmental agencies, and/or in accordance with the recommendations of the geotechnical consultant. COMPLETiON Obsen/ation, 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 obsen/ations of the work, final reports should be submitted, and may be subject to review by the controlling governmental agencies. No further excavation orfilling 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 shouldbe undertaken assoon as practical after completion of grading. PRELIMINARY OUTDOOR POOL/SPA DESIGN RECOMMENDATIONS The foliowing 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 condftions, including a subsurface investigation, differential settlement potential, expansive and corrosive soil potential, proximity ofthe proposed pool/spa to any slopes with regard to slope creep and lateral fill extension, as well as slope setbacks per codc, and geometry ofthe proposed Mr. Ted Hagey AppendixB File: e:\.S700\S701.upg Page 7 GemS&its^ lme. improvements. Recommendations for pools/spas and/or deck flatwork underlain by expansive soiis, or for areas with differential settlement greater than y4-lnGh over 40 feet horizontally, will be moreonerousthanthe preliminary recommendationspresented below. The 1:1 (h:v) Influence zone of any nearby retaining wall site stmctures 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 tower-most heel of the retaining structure, te the daylight grade of the nearby building pad or slope. If pools/spas or associated pool/spa improvements are constructed within tii is zone, they should be re-posftloned (horizontally or vertically) so tiiat tiiey are supported by earth materials that are outside or below this 1:1 plane, ff this is not possible given the area ofthe 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 tiie fijlure. unless they are periodicajly repaired and maintained • The condftions and recommeridatlons 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 shouid be 60 pounds per cubic foot (pef) for pool/spa walls with level backfill, and 75 pcf for a 2:1 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 pef, 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 forees. 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 consfruction 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 H is 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. Mr.Ted.Hagey ~ l^i^?^ Fits; e:VS700V^701 .upg Page 8 C€©S#f Isy ine. 7. The soil beneath the pool/spa bottom should be uniformly moist with the same stiflFness throughout Ifa 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 Indies below the poOly^pa shell. If \^ry low expansive soil is used for fill, the fill should be placed at a minimum of 95 percent relMive compaction, at optimum moisture concUtions. Tiiis requimment should be 90 percent relative compaction at over optimum moisture if the pool/spa Is constmcted wittiin or near expansive soils. The potential tor 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 constmction. 8. Ifthe pool/spa Is founded entirely In compactedfill 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 befitted with slip or expandlble joints between connections transecting varying soil conditions. 11. An elastic expansion joint (flexiblewsterprobf 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 ofthe 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 shouid 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 shouid consist of a 1- to 2-inGh 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 Mr. Ted Hagey Appendix B File: e:\5700\5701 .upg Page 9 GeoBoiis^ Ine, Improvements, deck slabs or flatwork should not be constmcted 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 properiy eompaeted fill. Fill should be compacted to achieve a minimurri 90 percent relative cJompacHon, 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 deptti of af least 1 Sihches below ttie 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 unsightiy shrinkage cracks. 15. In order to reduce unsightly cracking, the outer edges of poolyfepa decking to be bordered by landscaping, and the edges immediately adjacent to the pool/spa. shouW be underiain 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 of4,000 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 shou Id 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 french walls/backcuts at the angle of repose (typically 25 to 45 degrees), should be anticipated. AjJ excavations should be obsen/ed by a representative ofthe 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'tocal safety codes. Should adverse conditions exist, appropriate recommendations should be offered atthattime bythe geotechnical consultant GS! does not consult in the area of safety engineering and the safety of the construction crew is the responsibility ofthe pool/spa builder. Mr. Ted Hagey X"ppendix B File; e:\5700\S701 .upg Page 10 GeoSoiiSf Ine, 19. It is imperative that adequate provisions for surface dranage are Incorporated by ttie homeowners into their overall Improvement scrfieme. Ponding water, ground saturation and flow over slope faces, are all slftjatlons which must be avoided to enhance long tenn perfomianGe of the pool/spaand associated impnavements, and reduce the UkelihOod bf dfertress. 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 mfttgate the affects of creep, lateral fill exEensfon, 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 wthin 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," sueh that tfie poolyfepa Is surrcjunded by 5 feet of very low to low expansive soils (without ineduciblc 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 underthis 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 ofthe pool/spa shell such that the 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 instaliedforleakdeteGtlonpurposes. Piers that support the pool/spa should be a minimum of 12 inches in diameter and at a spacing to provide vertica! 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, ft will not eliminate these potentials, nor make the pool/spa "leak-free." Mr. Ted Hagey A^endix"B File: e:\5700\5701.upg p^g^ ^ Ge&S&ilM^ Inc, 22. The temperature cif 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 reeommendations, as warranted. Concrete mix design should be reviewed by a qualified corrosion consultant and materials engineer. 23. All pool/Spa utililY fr-enches should be eompaeted 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 tiie primary structure's utilfty lines (i.e., not stacked, or sharing of trenches, etc.). 25. The pool/spa or associated utilities should not intercept. Infenupt or othenvise adversely impact any area drain, n30f drain, or otherdmlnage conveyances. If It is neeessary 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 fiJrther reviewed and approved by the geotechnical consuttant, prior to proceeding with any further construction. 26. The geotechnieal oonsultant should review and approve all aspects of pool/spa and flatwork design prior to constmction. A design civil engineer should review all aspects of such design, including drainage and setback conditions. Prior to acceptance of the pool/spa conslruGtion, the projeet 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 construGtion should be reviewed and approved by the geotechnical consultant, including during excavation, priorto the placement of any additional fill, prior to the placement of any reinforcement or pouring of any concrete. 28. Any changes in design 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 geotechnica! 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 ofthe top of a slope, and/or H/3. where H is the height of ttie slope (in feet), wiH experience some movement or tilting. While the pool/spa shell or coping may not necessarily crack, the levelness of the pool/spa will likely tift toward the slope, and may not be esthetically pleasing. The same is true with decking, flatwork and other improvements in this zone. Mr. Ted Hagey AppendixB File; e;V^700\5701 upg p^g^ ^ ^ GemS&Ms. ine. 30. Failure to adhere to the above recommendations will significantiy increase the potential for distress to the pool/spa, flatwork, etc. 31. Local seismicity and/or the design earthquake vwll cause some distress to the pool/spa and decking or flatworic, possibly Including total functional and economic loss. 32. IThelnfcffniatlon and recxsmm^ discussed above should be provided to any contractors and/or subcontractors, or homeowners, interested/afleeted parties etc that may perform or may be affected by such work. JOB SAFETY General At GSl. gettingtiie Job done safely fe of primary concern. The foltowing is ttie company's safety con^derations tor use by all employees on multi-employer constraction sites On-ground personnel are at highest risk of injury, and possible fatality, on grading and constmction projects. GSl recognizes feat construction activities will 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 cDntractor, and GSI personnel must be maintained.' In an effort to minimize risks associated with geotechnical testing and obsen/ation the following precautions are to be Implemented for the safety of field personnel on grading and construction projects- Safety Meetings: GSl 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 GSl personnel, at all times, when they are working In the field. Safely Flags: Two safety flags are provided to GSl 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 fee grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative obsen/es ariy of our personnel not following the above, we request that ft be brought to the attention of our office. Mr. Ted Hagey —-——--, „ AppendixB File: e:\5700\570l.upg '* Page 13 GeoSoitg. Ine. Test Pits Loeatibn. Orieitiation. and Clearance The technician Is responsible for selecting testpit locations. A primary concern should be the technician's safety. Efforts will be made to coordinate locations wife the grading contractor's authorized repFesentative, and to select locations following or behind the establlshed tralfic pattern , preferably outside of cunent traffic. The confractor's authorized representative (^pendsor, grade checker, dump man. operator, etc.) should direct excavation of the pft and safety during the test period. Of paramount concern should be the soil technician's ^fety, and obtaining enough tests to represent the fill Test pits should be excavated so that fee spoil pile is placed away from oncoming trafflc, 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 coritfactor may wish to park a piece of equipment in front ofthe test holes, particularly in srnall fill areas or feose wife limited access. A zone of non-eneroaGhment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feetoutward 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 parte the vehicle directly above or below the test location. If fels is not possible, a prominent flag should be placed at the top of the slope. The contractor's repiesentative should eflectively keep all equipment at a safe operational distance (e.g., SO feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of thefill 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 ofthe contractor's failure to comply with any of the above, the technician Is required, by company poiicy, 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 fiirther 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 request that the contractor bring this to the technieian'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. Mr. Ted Hagey Appe^^dD^B File; e:\5700\5701 .upg Pggg 4 GeoS&it^f Inc, Trench and Vertical ExcavaaOn It is the contractor's respqnsibllfty to provide safe access into tienches whem compaction testing IS needed, Qur personnel are directed not to enter any excavation or vertical cut which: 1) IS 5 feet Of deeper Unless shored or laid back; 2) displays any evidence of tnsfebility.h9sany loose rockorofeerde french- or3) displays any ofeer evidence of any unsafe conditions regardless of depfe. All to-ench 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 ahy trench by being lowered or "riding down" on fee equipment. If tiie contractor feils to provide safe access to trenches for compaction testing our company policy requires fe^ fee soil techhiclan wifedraw and notily his/her supen/isor The contraetor's representative will be contacted In an effort to affect a solution All backfill not tested due to safety corteems or otherreasons could be subject to reprocessinq and/or removal. If GSl personnel become aware of anyone working beneath an unsafe fr-eneh wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately conect fee situation, ff con^ctive steps are not taken GSI feen has an obligation to noti^ Cal/OSHA and/or fee proper controlling authorities ' Mr. Ted Hagey ~* ——. _ . -r—zr File:e.A57W5701.upg Appendix B ^ ^ Page 15 Ge&SotlSy Ine,