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HomeMy WebLinkAboutCT 12-01; Miles Pacific Subdivision; Preliminary Geotechnical Evaluation; 2012-10-31PRELIMINABY ,QEOTECH(UCj^EVALUATION APNS 156-351^63, -07, AND -08, S373 AND 2375 PIO PjjCO DRIVE CARLSBAD, S Afj OIE GO 6oUNrY;t:AW^6RNfAi92008 MILES-PACIFiC, LLP C/O BHA, INC. 5115 AVENIDA ENCINAS, SUITE L CARLSBAD, CALIFORNIA 92008-8700 W.O. 6324-A-SC OCTOBER 31, 2012 Geotechnical • Geologic • Coastal • Environmental 5741 PalmerWay • Garlsbad, California 92010 • (760)438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com October 31, 2012 W.O. 6324-A-SC Miles-Pacific, LLP c/o BHA, Inc. 5115 Avenida Encinas, Suite L Carlsbad, California 92008-8700 Attention: IVIr. Rod Bradley Subject: Preliminary Geoteciinicai Evaluation, APNs 156-351-03, -07, and -08, 2373 and 2375 Pio Pico Drive, Carlsbad, San Diego County, California 92008 Dear Mr. Bradley: In accordance with the request and authorization of Mr. Robert Miles (Client), GeoSoils, Inc. (GSI) has performed a preliminary geotechnical evaluation ofthe subject site with respect to the proposed residential subdivision. The purpose of the study was to evaluate the onsite soils and geologic conditions, and their effects on the proposed site development from a geotechnical viewpoint. EXECUTIVE SUMMARY Based on our review of the available data (see Appendix A), field exploration, laboratory testing, and geologic and engineering analysis, the proposed development ofthe property appears to be feasible from a geotechnical viewpoint, provided the recommendations presented in the text of this report are properly incorporated into the design and construction ofthe project. The most significant elements ofthis study are summarized below: • Based on a review of the Tentative Map prepared by BHA, Inc. (2012), it is our understanding that proposed site development will consist of preparing the parcels forthe construction of 17 new single-family residential structures. GSI anticipates that the proposed residences will be one- to two-stories and consist of wood-frame and/or masonry construction with concrete slab-on-grade floors. Soils considered unsuitable for the support of settlement-sensitive improvements (i.e., residential structures, underground utilities, walls, pavements, etc.) and/or engineered fill include surficial undocumented artificial fill. Quaternary-age alluvium. Quaternary-age colluvium (topsoil), a Quaternary-age paleosol, and weathered Quaternary-age paralic deposits. Unweathered Quaternary-age younger and older paralic deposits are considered acceptable for the support of settlement-sensitive improvements and/or engineered fill in their existing state; however, they locally may be expansive. Based on the available data, the thickness of unsuitable soils across the site is anticipated to range between approximately 2 and 6V2 feet. However, localized areas of thicker unsuitable soils cannot be precluded and should be anticipated. All vegetation and/or deleterious materials should be removed from the site and properly disposed of, where located within the influence of new settlement-sensitive improvements and/or planned fills. Undocumented artificial fill. Quaternary-age colluvium, the Quaternary-age paleosol and weathered paralic deposits should be removed to expose suitable, unweathered younger and older paralic deposits prior to fill placement. The removed soils may be reused as engineered fill provided that major concentrations of vegetation and/or debris have been removed prior to their placement. It should be noted, that the 2010 California Building Code ([2010 CBC], California Building Standards Commission [CBSC], 2010) indicates that removals of unsuitable soils be performed across all areas to be graded, not just within the influence ofthe proposed residential structures. Relatively deep removals may also necessitate a special zone of consideration, on perimeter/confining areas. This zone would be approximately equal to the depth of removals, if removals cannot be performed onsite and offsite. Forthis site, the width ofthis zone is anticipated to be 2 to 6V2 feet, based on the available data. Any settlement-sensitive improvement (walls, brow ditches, curbs, streets, flatwork, etc.), constructed within this zone, may require deepened foundations, reinforcements, etc., orwill retain some potential for settlement and associated distress. This will require proper disclosure to all interested/affected parties, should this condition exist at the conclusion of grading. Based on our review of BHA, Inc. (2012) and the available subsurface data, perimeter walls constructed near property lines at Lots 18 and 19 and along the southerly side of Street "A", near the eastern margin ofthe site should be deepened such that footings penetrate and potentially compressible soils and are founded into unweathered paralic deposits. Based on the available subsurface data, this would require the retaining wall footings at the perimeter ofthe site to on the order of 5 feet below finish grade for a minimum 1 foot embedment into unweathered paralic deposits. The perimeter brow ditch will likely retain some potential for settlement-related distress if it is not supported by unweathered paralic deposits. In addition, foundations for top-of-slope walls and pool/spa shell bottoms, along or adjacent to perimeter fill slopes, should be deepened to provide at least 10 feet of horizontal setback from the bottom, outside edge of the foundation to the face of the descending slope if the complete removal and recompaction of potentially compressible soils below a 1:1 (horizontal to vertical [h:v]) projection, down from the toe of the fill slope, are constrained by property lines. Miles-Pacific, LLC ^ C! -i i W.O. 6324-A-SC File:wp12\6300\6324a.pge GeoSOUS, IltC. Page Two On a preliminary basis, temporary excavations greater than 4 feet, but less than 20 feet in overall height should conform to CAL-OSHA and/or OSHA requirements for Type "B" soils provided that groundwater and/or running sands are not present. All temporary excavations should be observed by a licensed engineering geologist or geotechnical engineer prior to worker entry. If temporary slopes conflict with property boundaries, shoring or alternating slot excavations may be necessary. The need for shoring or alternating slot excavations should be further evaluated during the grading plan review stage, but is considered likely on the eastern and northern property lines. Laboratory testing indicates that the expansion index of a tested sample of the onsite earth materials is less than 5 which correlates to very low expansion potential. However, Atterberg limits testing indicates that the plasticity index of a tested sample of the onsite soils is 20 which may correspond to a moderate expansion potential. As such, some ofthe onsite soils are considered expansive per Section 1803.5.2 ofthe 2010 CBC. Based on visual soil classification during the field exploration and laboratory testing, expansive soil conditions are generally associated with the Quaternary-age paleosol as well as some near surface layers within the younger and older paralic deposits encountered locally in subsurface explorations. Given the relatively limited horizontal and lateral extent of expansive soils when compared to the onsite soils exhibiting very low expansion characteristics, it is reasonable to believe that through proper soil blending during grading, finish grade soils will likely be non-detrimentally expansive. However, there is some potential that testing of finish grade soils may indicate the presence of detrimentally expansive soils. Thus on a preliminary basis, GSI is providing recommendations for conventional foundation designs as well as post-tension (PT) foundation systems should expansive finish grade soils be detected at the conclusion of grading. Soil pH, saturated resistivity, and soluble sulfate, and chloride testing was performed on representative samples of the onsite soils. Testing indicates that these soils are mildly to moderately alkaline with respectto soil acidity/alkalinity, are corrosive to exposed, buried metals when saturated, possess negligible sulfate exposure to concrete, and are below the action level for chloride exposure (per State of California Department of Transportation, 2003). Reinforced concrete mix design for foundations, slab-on-grade floors, and pavements should minimally conform to "Exposure Class Cl" in Table 4.3.1 of ACI 318-08, as concrete would likely be exposed to moisture. GSI does not consult in corrosion engineering. Therefore, additional comments and recommendations may be obtained from a qualified corrosion engineer based on the level of corrosion protection desired or required for the project, as determined by the project architect and/or structural engineer. The planned perimeter cut slopes will likely expose colluvium, weathered paralic deposits, and a local paleosol along the face of slope following construction. Due Miles-Pacific, LLC _ W.O. 6324-A-SG Flle:wp12\6300\6324a.pge GcoSoils, ItlC. Page Three to insufficient space for corrective grading (i.e., stabilization), these slopes may retain some potential for erosion and sloughing. An erosion control mat such as MacMat-R (http://www.maccaferri.co.uk/PAGES00295.html) may be used to reduce erosion on perimeter cut slopes 5 feet or greater in overall height. Planned perimeter fill slopes greater than 5 feet in overall height where the removal and recompaction of potentially compressible soils cannot be completed below a 1:1 projection down from the toe ofthe sloe may experience some fill relaxation and settlement. Therefore, GSI recommends that foundations for any portion of the planned residential structures or pools/spas maintain a minimum horizontal distance of 10 feet as measured from the bottom outside edge of the foundation to the face of the descending fill slope. Flatwork or pavements located within 20 horizontal feet from the tops of such fill slopes may retain some potential for settlement-related distress. This should be disclosed to all interested/affected parties. Regional groundwater was not encountered during our field exploration and is not expected to be a major factor during construction of the proposed improvements. Regional groundwater is anticipated to generally be coincident with Mean Sea Level (MSL) or approximately ±82 feet below the lowest existing site elevation. However, due to the nature of the site materials, seepage and/or perched groundwater conditions may develop throughout the site in the future, both during and subsequent to development, especially along boundaries of contrasting permeabilities (i.e., clayey and sandy fill lifts, fill/paralic deposits and younger and older paralic deposits contacts, joints/fractures, discontinuities, etc.), and should be anticipated. Based on our experience with other projects in the vicinity, GSI anticipates that perched water likely exists along the geologic contact ofthe older paralic deposits and underlying Santiago Formation. This potential for post- development perched water to manifest should be disclosed to all interested/affected parties. Thus, more onerous slab design is necessary for any new slab-on-grade floor (State of California, 2011). Recommendations for reducing the amount of water and/or water vapor through slab-on-grade floors are provided in the "Soil Moisture Considerations" sections ofthis report. It should be noted that these recommendations should be implemented if the transmission of water or water vapor through the slab is undesirable. Should these mitigative measures not be implemented, then the potential for water or vapor to pass through the foundations and slabs and resultant distress cannot be precluded, and would need to be disclosed to all interested/affected parties. • No landslides or adverse geologic structure, associated with deep-seated landsliding, were encountered during our field exploration. The formational earth materials (i.e., paralic deposits) that underlie the site are typically moderately to well indurated and do exhibit adverse geologic structure, based on the available data. Therefore, it is our professional opinion thatthe potential for deep-seated landslides to adversely affect the proposed development is considered very low. However, the Miles-Pacific, LLC _ W.O. 6324-A-SG File:wp12\6300\6324a.pge GcoSoilS, ItlC. Page Four onsite earth materials are considered erosive. Thus, there is some potential for shallow, surficial slope failures to occur along graded slopes. However, provided that the recommendations in this report are incorporated into the civil engineering and landscape designs and surface runoff waters are directed away from the tops of slopes, this potential would be greatly reduced. Our evaluation and experience with similar sites indicates that the site currently has a very low potential for liquefaction, due to the relatively dense nature ofthe paralic deposits and underlying Santiago Formation, and the depth to the regional water table belowthe lowest site elevation. The potential for seismic densification to affect the planned development is considered very low, provided the recommendations in this report are properly followed. However, some seismic densification of the adjoining un-mitigated site(s) may adversely influence planned improvements atthe perimeter of the site. The planned desilting basins at Lots 18 and 19 will require specific design detailing and proper maintenance over their life so as to not adversely affect the cut slope that descends to Interstate 5 nor adjacent planned improvements. The seismic acceleration values and design parameters provided herein should be considered during the design of the proposed development. The adverse effects of seismic shaking on the structure(s) will likely be wall cracks, some foundation/slab distress, and some seismic settlement. However, it is anticipated that the structure will be repairable in the event of the design seismic event. This potential should be disclosed to all interested/affected parties. Our evaluation indicates there are no known active faults crossing the site. In addition, other than moderate to strong seismic shaking produced from an earthquake on a nearby active fault, other geologic and secondary seismic hazards have a very low potential to affect the proposed site development. Adverse geologic features that would preclude project feasibility were not encountered. The recommendations presented in this report should be incorporated into the design and construction considerations of the project. Miles-Pacific, LLC ^ W.O. 6324-A-SG File:wpl2\6300\6324a.pge GcoSoUs, ItlC. Page Five The opportunity to be of service is greatly appreciated. If you have any questions concerning this report, or if we may be of further assistance, please do not hesitate to contact any of the undersigned. Respectfully submitted, GeoSoils, Inc. Ryan Boehmer Project Geologist David W. Skelly Civil Engineer, RCE 4^ P. F'rankli Engineering Geologist, RB/JPF/DWS/jh Distribution: (4) Addressee (1) Miles-Pacific, LLC, Attention: Mr. Robert Miles Miles-Pacific, LLC File:wp12\6300\6324a.pge GeoSoils, Inc. w.o. 6324-A-SC Page Six TABLE OF CONTENTS SCOPE OF SERVICES 1 SITE DESCRIPTION AND PROPOSED DEVELOPMENT 1 SITE EXPLORATION 3 REGIONAL GEOLOGY 3 SITE GEOLOGIC UNITS 4 Artificial Fill - Undocumented (Map Symbol - Afu) 4 Quaternary-age Alluvium (Map Symbol - Qal) 4 Quaternary-age Colluvium (Not Mapped) 5 Quaternary-age Paleosol (Not Mapped) 5 Quaternary-age Younger Paralic Deposits (Map Symbol - Qyp) 5 Quaternary-age Older Paralic Deposits (Map Symbol - Qop) 6 Tertiary Santiago Formation 6 GEOLOGIC STRUCTURE 6 GROUNDWATER 6 MASS WASTING/U\NDSLIDE SUSCEPTIBILITY 7 FAULTING AND REGIONAL SEISMICITY 8 Local and Regional Faults 8 Seismicity 8 Deterministic Maximum Credible Site Acceleration 8 Historical Site Acceleration 9 Probabilistic Site Acceleration 9 Seismic Shaking Parameters 9 LIQUEFACTION POTENTIAL 10 Liquefaction 10 Seismic Densification 11 Summary 11 Other Geologic/Secondary Seismic Hazards 12 LABORATORYTESTING 12 General 12 Classification 12 Moisture-Density Relations 13 Expansion Potential 13 Atterberg Limits 13 Particle - Size Analysis 13 GeoSoils, Inc. Saturated Resistivity, pH, and Soluble Sulfates, and Chlorides 14 Corrosion Summary 14 EMBANKMENT FACTORS (SHRINKAGE/BULKING) 14 EXCAVATION FEASIBILITY 15 PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS 15 EARTHWORK CONSTRUCTION RECOMMENDATIONS 18 General 18 Demolition/Grubbing 19 Remedial Removals (Removal of Potentially Compressible Surficial Materials) 19 Overexcavation 20 Temporary Slopes 20 Engineered Fill Placement 20 Graded Slopes 21 Import Fill Materials 21 PRELIMINARY FOUNDATION RECOMMENDATIONS 22 General 22 General Foundation Design 23 Foundation Settlement 24 PRELIMINARY FOUNDATION CONSTRUCTION RECOMMENDATIONS 24 Conventional Foundations (Expansion Index of 20 or Less with a Plasticity Index Less Than 15) 24 Post-Tensioned Foundations 25 Soil Moisture 26 Perimeter Cut-Off Walls 26 Post-Tensioned Foundation Design 26 Soil Support Parameters 27 CORROSION 28 SOIL MOISTURE TRANSMISSION CONSIDERATIONS 28 WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS 30 Conventional Retaining Walls 30 Restrained Walls 31 Cantilevered Walls 31 Seismic Surcharge 32 Retaining Wall Backfill and Drainage 32 Wall/Retaining Wall Footing Transitions 36 Miles-Pacific, LLC ^ Table of Gontents File:wp12\6300\6324a.pge GeoSoilS, InC. Page ii TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS 36 Expansive Soils and Slope Creep 36 Top of Slope Walls/Fences 37 EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS 38 PRELIMINARY PAVEMENT DESIGN 40 New Pavements 40 New Asphaltic Concrete (AC) Pavement 40 Pavement Grading Recommendations 41 General 41 Subgrade 41 Aggregate Base 41 Paving 42 Drainage 42 ONSITE INFILTRATION-RUNOFF RETENTION SYSTEMS 42 General 42 Plan Specific 46 PRELIMINARY OUTDOOR POOLVSPA DESIGN RECOMMENDATIONS 46 General 46 DEVELOPMENT CRITERIA 52 Slope Deformation 52 Slope Maintenance and Planting 52 Drainage 53 Erosion Control 53 Landscape Maintenance 53 Gutters and Downspouts 54 Subsurface and Surface Water 54 Site Improvements 54 Tile Flooring 55 Additional Grading 55 Footing Trench Excavation 55 Trenching/Temporary Construction Backcuts 55 Utility Trench Backfill 56 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICALOBSERVATION AND TESTING 56 OTHER DESIGN PROFESSIONALS/CONSULTANTS 57 PU\N REVIEW 58 Miles-Pacific, LLC _ Table of Gontents File:wp12\6300\6324a.pge GeoSoilS, InC. Page jji LIMITATIONS 58 FIGURES: Figure 1 - Site Location Map 2 Detail 1 - Typical Retaining Wall Backfill and Drainage Detail 33 Detail 2 - Retaining Wall Backfill and Subdrain Detail Geotextile Drain 34 Detail 3 - Retaining Wall and Subdrain Detail Clean Sand Backfill 35 ATTACHMENTS: Appendix A - References Rear of Text Appendix B - Test Excavation Logs Rear of Text Appendix C - EQFAULT, EQSEARCH, and PHGA Rear of Text Appendix D - Laboratory Data Rear of Text Appendix E - General Earthwork and Grading Guidelines Rear of Text Plate 1 - Geotechnical Map Miles-Pacific, LLC _ Table of Contents File:wp12\6300\6324a.pge GeoSollS, IttC. Page iv PRELIMINARY GEOTECHNICAL EVALUATION APNS 156-351-03, -07, AND -08, 2373 AND 2375 PIO PICO DRIVE CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA 92008 SCOPE OF SERVICES The scope of our services has included the following: 1. Review of the available geologic literature for the site (see Appendix A). 2. Geologic site reconnaissance, subsurface exploration with four exploratory test excavations and four hand-auger borings (see Appendix B), sampling, and mapping. 3. General areal seismicity evaluation (see Appendix C). 4. Appropriate laboratory testing of representative soil samples (Appendix D). 5. Engineering and geologic analysis of data collected. 6. Preparation of this report. SITE DESCRIPTION AND PROPOSED DEVELOPMENT The subject site consists of three relatively vacant parcels, located west of Pio Pico Drive and east of the Interstate 5 freeway in Carlsbad, San Diego County, California (see Figure 1, Site Location Map). The site is bounded by existing residential development and Pio Pico Drive to the east, by the Interstate 5 freeway to the west, and by existing residential development to the remaining quadrants. The physical address ofthe site is 2373 and 2375 Pio Pico Drive. According to the 30-scale tentative map prepared by BHA, Inc., site elevations range between approximately 82 to 110 feet NAVD29. Topographically, the site is generally flat-lying to very gently sloping in a southwesterly direction. The overall gradient ofthe site is on the order of 16:1 (horizontahvertical [h:v]). Near the western margin of the site, an approximately 33-foot high cut slope descends toward the Interstate 5 freeway. The overall gradient ofthis slope is approximately 1.9:1 (h:v). Existing onsite structures include canopies for the currently operating tree nursery. Based on a review of BHA, Inc. (2012), proposed development will consist of preparing the site for the construction 17 new single-family residences, with associated infrastructure (e.g., underground utilities, streets, sidewalks, etc.). Cut and fill grading techniques will be necessary to achieve the design grades with maximum planned cuts and fills on the order of ±6V2 and ±6 feet respectively. Grade differentials will be accommodated by the construction of graded 2:1 (h:v) or flatter cut and fill slopes and concrete masonry unit GeoSoils, Inc. Base Map: TOPO!® ©2003 National Geographic, U.S.G.S San Luis Rey Quadrangle, California - San Diego Co., 7.5 Minute, dated 1997, current, 1999. SITE NOT TO SCALE Base Map: Yahoo! Maps, Maps by Nokia, Copyright 2011 Digital Globe This map is copyrighted by Digital Giobe. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. All rights reserved. N W.O. 6324-A-SC SITE LOCATION MAP Figure 1 (CMU) retaining wall. The maximum heights of graded cut and fill slopes shown on BHA, Inc. are approximately ±6 feet and ±8 feet, respectively. The maximum height of CMU retaining walls is approximately ±5V2 feet. Storm water will be directed into two detention basins near the western margin of the site, prior to introduction into the regional system in the existing brow ditch on the cut slope descending to Interstate 5. Sanitary sewerage disposal is anticipated to be tied into the municipal system. GSI anticipates that the proposed residences will be one- to two-stories and consist of wood-frame and/or masonry construction with concrete slab-on-grade floors. GSI assumes that the residential structures will be relatively lightly loaded, typical ofthis type of development. SITE EXPLORATION Surface observations and subsurface explorations were performed in late September, 2012, by a representative of this office. A survey of line and grade for the subject site was not conducted by this firm at the time of our site reconnaissance. Near-surface soil and geologic conditions were explored with four exploratory test pit excavations and four hand-auger borings within the site. A rubber-tire backhoe was used to complete the test pit excavations and a manual auger was used to accomplish the test borings. Given that the site is currently an operating tree farm, the test pit excavations were sited in areas that could be reasonably accessed bythe backhoe. The hand borings were performed where access bythe backhoe was limited. The approximate locations of the exploratory test pit excavations and borings are shown on the Geotechnical Map (see Plate 1) which uses BHA, Inc. (2012) as a base. Logs ofthe test pit excavations and hand borings are presented in Appendix B. REGIONAL GEOLOGY The subject property lies within the coastal plains physiographic region ofthe Peninsular Ranges Geomorphic Province of southern California. This region consists of dissected, mesa-like terraces that graduate inland to rolling hills. The encompassing Peninsular Ranges Geomorphic Province is characterized as elongated mountain ranges and valleys that trend northwesterly (Norris and Webb, 1990). This geomorphic province extends from the base ofthe east-west aligned Santa Monica - San Gabriel Mountains, and continues south into Baja California. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks, Jurassic metavolcanic rocks, and Cretaceous plutonic rocks ofthe southern California batholith. In the San Diego County region, deposition occurred during the Cretaceous Period and Cenozoic Era in the continental margin of a forearc basin. Sediments, derived from Cretaceous-age plutonic rocks and Jurassic-age volcanic rocks, were deposited into the Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad ^ October 31, 2012 Flle:wp12\6300\6324a.pge GeoSoilS, InC. Page 3 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. During mid- to late-Pleistocene time, this plain was uplifted, eroded, and incised. Alluvial deposits have since filled the lower valleys, and young marine sediments are currently being deposited/eroded within coastal and beach areas. Regional geologic mapping by Kennedy and Tan (2005) indicates thatthe contact between younger and older paralic deposits (formerly termed terrace deposits) occurs near the site's easterly margin. Observations during our field exploration generally indicated younger paralic deposits overlying older paralic deposits near the easterly site boundary, with a general thickening of the younger paralic deposits to the west. SITE GEOLOGIC UNITS The site geologic units encountered during our subsurface investigation and site reconnaissance included small, localized areas undocumented artificial fill, localized Quaternary-age alluvium, Quaternary-age colluvium (topsoil), a Quaternary-age paleosol, and younger and older Quaternary-age paralic deposits (weathered and unweathered). The earth materials are generally described below from the youngest to the oldest. The distribution ofthe mappable units across the site is shown on Plate 1. Artificial Fill - Undocumented (Map Symbol - Afu) Although not directly observed in the subsurface explorations, artificial fill likely supports a shed near the northern margin of the site and occur near a man-made drainage swale, near the southwestern corner ofthe site (see Plate 1). The undocumented fill appeared to consist of a dark yellowish brown silty sand. The fill appeared dry, loose, and non-uniform. The thickness of the undocumented fill may be on the order of 1 foot thick, where encountered. The undocumented fill is considered unsuitable forthe support ofthe proposed settlement-sensitive improvements and/or planned fill in its existing state. Removal and recompaction ofthese materials is recommended where settlement-sensitive improvements and/or planned fill will occur within its influence. Quaternary-age Alluvium (Map Symbol - Qal) Quaternary-age (recent) alluvium was encountered near the surface in Test Pit TP-3. These materials generally consisted of a gray and yellowish brown sand and were approximately 7 inches thick, where encountered. The alluvium was dry and medium dense. The alluvium is considered potentially compressible in its existing state and therefore should be removed and recompacted, if settlement-sensitive improvements and/or planned fill are proposed within its influence. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 Fjle:wpl2\6300\6324a.pge GeoSoilS, InC. Page 4 Quaternary-age Colluvium (Not Mapped) Quaternary-age colluvium (topsoil) was encountered in all ofthe subsurface explorations. The colluvium generally consisted of a brown and dark brown silty sand with local minor clay to a dark brown very fine-grained sand with silt. The colluvium was generally dry to moist. The colluvium within test pits excavated in the existing dirt roads was generally dense at the surface but became medium dense with depth. The denseness of the colluvium observed in these excavations was likely due to compaction from vehicular traffic. Outside of the roads, the colluvium was typically loose to medium dense. In general, the thickness of the colluvium was on the order of %-foot to 1 feet. Due to its locally porous nature and general low density, the colluvium is considered potentially compressible in its existing state and therefore should be removed and recompacted, if settlement-sensitive improvements and/or planned fill are proposed within its influence. Quaternary-age Paleosol (Not Mapped) A Quaternary-age paleosol (i.e., buried soil horizon) was observed underlying the younger paralic deposits and developed within the underlying older paralic deposits in Test Pit TP-1. The paleosol consisted of a dark yellowish red clayey sand that was moist and medium dense. It generally exhibited weak prismatic ped structures with abundant clay films on ped faces. The paleosol was slightly porous. Based on its absence within the other test pits and hand borings, GSI believes that areal extent of the paleosol is limited. Where encountered, the thickness of the paleosol was approximately ^V4 feet. Due to its visible porosity, the paleosol may be potentially compressible in its existing state and therefore should be removed and recompacted, if settlement-sensitive improvements and/or planned fill are proposed within its influence. Quaternary-age Younger Paralic Deposits (Map Symbol - Qyp) Quaternary-age younger paralic deposits were encountered underlying the surficial soils in all ofthe subsurface explorations. These deposits were observed to overlie older paralic deposits in Test Pits TP-1 and TP-2 and all the hand auger borings (HA-1 through HA-4). The younger paralic deposits were generally weathered in the upper ±y2-footto ±3y2feet of their vertical extent. Where weathered, the younger paralic deposits typically consisted of a dark yellowish brown silty sand to a very fine-grained sand with silt. The weathered younger paralic deposits were generally dry to wet and medium dense. Locally, the weathered portions contained trace quantities of iron-stone concretions. Weathered younger paralic deposits exhibited local porosity up to approximately y4-inch in diameter. Unweathered younger paralic deposits generally consisted of a dark yellowish brown sand with cobble to sandy cobbles, a dark yellowish brown clayey sand, and a dark yellowish brown and gray sandy clay. The unweathered younger paralic deposits were typically moist to wet and dense/stiff. Weathered younger paralic deposits are considered potentially compressible in their existing state and therefore should be removed and recompacted if settlement-sensitive improvements and/or planned fills are proposed within Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 5 their influence. Unweathered younger paralic deposits are considered suitable for the support of settlement-sensitive improvements and/or planned fill in their existing state. Quaternary-age Older Paralic Deposits (Map Symbol - Qop) Older paralic deposits were observed underlying younger paralic deposits in Test Pits TP-1 and TP-2 and all the hand auger borings (HA-1 through HA-4). These deposits generally consisted of a dark yellowish brown and reddish yellowsilty sand to very fine-grained sand with silt, a gray, dark yellowish brown, and reddish yellow clayey sand, and a reddish yellow and dark yellowish brown sandy clay. The older paralic deposits were generally damp to moist and dense to very dense/very stiff. The older paralic deposits are considered suitable forthe support of settlement-sensitive improvements and/or planned fills in their existing state. Tertiary Santiago Formation Although not encountered in ourtest excavations and borings, sedimentary rock belonging to the Tertiary-age Santiago Formation, underlies the older paralic deposits at depth. As observed in test borings completed in preparation of GSI (2003), the Santiago Formation consisted of highly oxidized reddish brown and light brown, damp to moist, fine-to medium-grained clayey sandstone to silty sandstone. These materials are medium dense/medium stiff and become dense/stiff with depth. The Santiago Formation was encountered at an elevation of approximately 49 feet MSL in borings advanced in preparation of GSI (2003). Based onthe planned excavations shown on BHA, Inc. (2012), encountering the Santiago Formation during site earthwork is not anticipated. GEOLOGIC STRUCTURE As observed within the test pits, the younger and older paralic deposits were thickly bedded to massive and regionally sub-horizontal to horizontal. A review of GSI (2003) indicates clayey interbeds within the underlying Santiago Formation displayed relatively horizontal contacts within the bounding sandstone units. Based on the available data, adverse geologic structures are not anticipated to unfavorably affect the proposed development. GROUNDWATER Regional groundwater was not encountered during our field exploration and is not expected to be a major factor during construction of the proposed minor subdivision. Regional groundwater is anticipated to generally be coincident with MSL or approximately 82 feet below the lowest existing site elevation. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 6 Due to the nature of the site earth materials, seepage and/or perched groundwater conditions may develop throughout the site in the future, both during and subsequent to development, especially along boundaries of contrasting permeabilities (i.e., sandy/clayey fill lifts, fill/paralic deposit contacts, bedding, joints/fractures, discontinuities, etc.), and should be anticipated. This potential should be disclosed to all interested/affected parties. Based on our experience with other projects in the vicinity, perched water likely exists along the geologic contact between the older paralic deposits and underlying Santiago Formation. Based on regional geologic mapping by Tan and Kennedy (1996), the elevation ofthis contact is approximately 60 feet Mean Sea Level (MSL) in the vicinity ofthe site. Tan and Kennedy (1996) show this contact dipping in a westerly direction. Based on GSI field work performed at a site located near the intersection of Jefferson Street and Las Flores Drive, the elevation of this geologic contact was observed at approximately 49 feet MSL. Thus, groundwater perched along this contact may occur between approximately 22 and 33 feet below the lowest existing elevation. Based on our review of BHA, Inc. (2012), planned excavations will not extend to these depths. Due to the potential for post-development perched water to manifest near the surface, owing to as-graded permeability contrasts, more onerous slab design is necessary for any new slab-on-grade floor (State of California, 2012). Recommendations for reducing the amount of water and/or water vapor through slab-on-grade floors are provided in the "Soil Moisture Considerations" sections of this report. It should be noted that these recommendations should be implemented if the transmission of water or water vapor through the slab is undesirable. Should these mitigative measures not be implemented, then the potential for water or vapor to pass through the foundations and slabs and resultant distress cannot be precluded, and would need to be disclosed to all interested/affected parties. MASS WASTING/LANDSLIDE SUSCEPTIBILITY According to regional landslide susceptibility mapping by Tan and Giffen (1995), the site is located within landslide susceptibility Subarea 3-1 which is characterized as being "generally susceptible" to landsliding. Based on our review of Kennedy and Tan (2005), no landslide debris has been mapped within the site. In addition, GSI did not observe geomorphic expressions indicative of deep-seated landslides during our review of available stereoscopic aerial photographs (United States Department of Agriculture [USDA], 1953). Further, landslide debris or adverse geologic structure were not encountered during our field investigation. Given the above positive evidence, and the moderately to well indurated nature of the younger and older paralic deposits that underlie the site, it is our opinion that the potential for deep-seated landslides to adversely affect the proposed development is considered very low. However, the onsite earth materials are considered erosive. Thus, there is some Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad ^ October 31, 2012 File:wp12\6300\6324a.pge GeoSollS, InC. Page 7 potential for shallow, surficial slope failures to occur along graded slopes or the cut slope that descends to Interstate 5. However, provided that the recommendations in this report are incorporated into the civil engineering and landscape designs and surface runoff waters are directed away from the tops of slopes, this potential would be greatly reduced. FAULTING AND REGIONAL SEISMICITY Local and Regional Faults Our review indicates that there are no known active faults crossing this site, and the site is not within an Alquist-Priolo Earthquake Fault Zone (Bryant and Hart, 2007). However, the site is situated in an area of active faulting. These include, but are not limited to: the San Andreas fault; the San Jacinto fault; the Elsinore fault; the Coronado Bank fault zone; and the Newport-Inglewood - Rose Canyon fault zone (NIRCFZ). Portions of the nearby NIRCFZ are located in an Alquist-Priolo Earthquake Fault Zone (Bryant and Hart, 2007). The location of these, and other major faults relative to the site, are indicated on the California Fault Map in Appendix C. According to Blake (2000a), the closest known active fault to the site is the offshore segment ofthe Newport-Inglewood fault which located at a distance of approximately 5.3 miles [mi] (8.5 kilometers [km]). According to Cao, et al. (2003), the offshore segment of the Newport-Inglewood fault is capable of producing a maximum magnitude (MJ 7.1 earthquake. The possibility of ground acceleration, or shaking at the site, may be considered as approximately similar to the southern California region as a whole. Major active fault zones that may have a significant affect on the site, should they experience activity, are listed in Appendix C (modified from Blake, 2000a). Seismicity Deterministic Maximum Credible Site Acceleration The acceleration-attenuation relation of Bozorgnia, Campbell, and Niazi (1999) has been incorporated into EQFAULT (Blake, 2000a). EQFAULT is a computer program developed by Thomas F. Blake (2000a), which performs deterministic seismic hazard analyses using digitized California faults as earthquake sources. The program estimates the closest distance between each fault and a given site. If a fault is found to be within a user-selected radius, the program estimates peak horizontal ground acceleration that may occur at the site from an upper bound ("maximum credible") earthquake on that fault. Site acceleration (g) was computed by one user-selected acceleration-attenuation relation that is contained in EQFAULT. Based on the EQFAULT program, a peak horizontal ground acceleration from an upper bound event at the site may be on the order of 0.60 g. The computer printouts of pertinent portions ofthe EQFAULT program are included within Appendix C. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 8 Historical Site Acceleration Historical site seismicity was evaluated with the acceleration-attenuation relation of Bozorgnia, Campbell, and Niazi (1999), and the computer program EQSEARCH (Blake, 2000b). This program performs a search of the historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-kilometer radius, between the years 1800 through December 2011. Based on the selected acceleration-attenuation relationship, a peak horizontal ground acceleration is estimated, which may have effected the site during the specific event listed. Based on the available data and the attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 through December 2011 was 0.23 g. A historic earthquake epicenter map and a seismic recurrence curve are also estimated/generated from the historical data. Computer printouts ofthe EQSEARCH program are presented in Appendix C. Probabilistic Site Acceleration A probabilistic seismic hazards analysis was performed using 2008 Interactive Deaggregations (2012 update) Seismic Hazard Analysis tool available atthe USGS website (https://geohazards.usgs.gov/deaggnit/2008/) which evaluates the site specific probabilities of exceedance for selected spectral periods. Based on a review ofthese data, and considering the relative seismic activity ofthe southern California region as a whole, a probabilistic seismic hazard assessment is presented herein. Printouts from this analysis are also included in Appendix C. Seismic Shaking Parameters Based on the site conditions, the following table summarizes the site-specific design criteria obtained from the 2010 CBC (CBSC, 2010), Chapter 16 Structural Design, Section 1613, Earthquake Loads. The computer program Seismic Hazard Curves and Uniform Hazard Response Spectra, provided by the United States Geologic Survey ([U.S.G.S.], 2011) was utilized for design. The short spectral response utilizes a period of 0.2 seconds. 2010 CBC SEISMIC DESIGN PARAMETERS 1 PARAMETER •—t— VALUE! IBC-06 REFERENCE Site Glass D Table 1613.5.2 Site Coefficient, F^ 1.0 Table 1613.5.3(1) Site Coefficient, F^, 1.517 Table 1613.5.3(2) Maximum Considered Earthquake Spectral Response Acceleration (0.2 sec), S^s 1.281g Section 1613.5.3 (Eqn 16-37) IVIaximum Considered Earthquake Spectral Response Acceleration (1 sec), S^^^ 0.733g Section 1613.5.3 (Eqn 16-38) Miles-Pacific, LLC 2373 & 2375 Pio Pico Drive, Garlsbad File:wp12\6300\6324a.pge GeoSoils, Inc. w.o. 6324-A-SG October 31, 2012 Page 9 2010 CBC SEISMIC DESIGN PARAMETERS PARAMETER VALUE IBC-06 REFERENCE 5% Damped Design Spectral Response Acceleration (0.2 sec), S^g 0.854g Section 1613.5.4 (Eqn 16-39) 5% Damped Design Spectral Response Acceleration (1 sec), SQ, 0.489g Section 1613.5.4 (Eqn 16-40) GENERAL SEISMIC DESIGN PARAMETERS Distance to Seismic Source (Newport-Inglewood fault [offshore segment]) from Blake (2000a) 5.3 mi. (8.5 km) Upper Bound Earthquake (Newport-Inglewood fault [offshore segment]) M^6.9*/7.^** Probabilistic Horizontal Site Acceleration ([PHSA] 10% probability of exceedance in 50 years) 0.27g Probabilistic Horizontal Site Acceleration ([PHSA] 2% probability of exceedance in 50 years) 0.49g * - International Conference of Building Officials (IGBO, 1998) ** - Cao, etal. (2003) Conformance to the criteria above for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur in the event of a large earthquake. The primary goal of seismic design is to protect life, not to eliminate all damage, since such design may be economically prohibitive. Cumulative effects of seismic events are not addressed in the 2010 CBC (CBSC, 2010) and regular maintenance and repair following locally significant seismic events (i.e., M^5.5) will likely be necessary. LIQUEFACTION POTENTIAL Liquefaction 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 vertical deformation, lateral movement, lurching, sliding, and as a result of seismic loading, volumetric strain and manifestation in surface settlement of loose sediments, sand boils and other damaging lateral deformations. This phenomenon occurs only belowthe watertable, but after liquefaction has developed, it can propagate upward into overlying non-saturated soil as excess pore water dissipates. Miles-Pacific, LLC 2373 & 2375 Pio Pico Drive, Garlsbad File:wp12\6300\6324a.pge GeoSoils, Inc. w.o. 6324-A-SG October 31, 2012 Page 10 Oneofthe primary factors controlling the potential for liquefaction is depth to groundwater. Typically, liquefaction has a relatively low potential at depths greater than 50 feet and is unlikely and/or will produce vertical strains well below 1 percent for depths below 60 feet when relative densities are 40 to 60 percent and effective overburden pressures are two or more atmospheres (i.e., 4,232 psf [Seed, 2005]). The condition of liquefaction has two principal effects. One is the consolidation of loose sediments with resultant settlement of the ground surface. The other effect is lateral sliding. Significant permanent lateral movement generally occurs only when there is significant differential loading, such as fill or natural ground slopes within susceptible materials. No such loading conditions exist at the site. Liquefaction susceptibility is related to numerous factors and the following five conditions should be concurrently present for liquefaction to occur: 1) sediments must be relatively young in age and not have developed a large amount of cementation; 2) sediments must generally consist of medium- to fine-grained, relatively cohesionless sands; 3) the sediments must have low relative density; 4) free groundwater must be present in the sediment; and 5) the site must experience a seismic event of a sufficient duration and magnitude, to induce straining of soil particles. Only about one to two of these concurrently necessary conditions have the potential to affect the site. Seismic Densification Seismic densification is a phenomenon that typically occurs in low relative density granular soils (i.e., United States Soil Classification System [USCS] soil types SP, SM, and) that are above the groundwatertable. These unsaturated granular soils are susceptible if left in the original density (unmitigated), and are generally dry ofthe optimum moisture content (as defined bythe ASTM D 1557). During seismic-induced ground shaking, these natural or artificial soils deform under loading and volumetrically strain, potentially resulting in ground surface settlements. Some densification of the adjoining un-mitigated properties may influence improvements at the perimeter of the site. Special setbacks and/or foundations may be utilized if significant structures/improvements are placed close to the perimeter of the site. Our evaluation assumed that the current offsite conditions will not be significantly modified by future grading at the time of the design earthquake, which is a reasonably conservative assumption. Summarv It is the opinion of GSI that the susceptibility of the site to experience damaging deformations from seismically-induced liquefaction and densification is relatively low owing to the dense, nature of the younger and older paralic deposits that underlie the site in the near-surface and the depth to the regional watertable. In addition, the recommendations for remedial earthwork and foundations would further reduce any significant liquefaction/densification potential. Some seismic densification of the adjoining Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Carlsbad _ October 31,2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Pagell un-mitigated site(s) may adversely influence planned improvements atthe perimeter of the site. However, given the remedial earthwork and foundation recommendations provided herein, the potential for the planned building to be affected by significant seismic densification or liquefaction of offsite soils may be considered low. Other Geologic/Secondary Seismic Hazards The following list includes other geologic/seismic related hazards that have been considered during our evaluation ofthe site. The hazards listed are considered negligible and/or mitigated as a result of site location, soil characteristics, and typical site development procedures: Subsidence Dynamic Settlement • Surface Fault Rupture • Ground Lurching or Shallow Ground Rupture • Tsunami • Seiche It is important to keep in perspective that in the event of an upper bound or maximum credible earthquake occurring on any of the nearby major faults, strong ground shaking would occur in the subject site's general area. Potential damage to any structure(s) would likely be greatest from the vibrations and impelling force caused by the inertia of a structure's mass than from those induced by the hazards considered above. Following implementation of remedial earthwork and design of foundations described herein, this potential would be no greater than that for other existing structures and improvements in the immediate vicinity that comply with current and adopted building standards. LABORATORY TESTING General Laboratory tests were performed on representative samples of the onsite earth materials in orderto evaluate their physical characteristics. The test procedures used and results obtained are presented below. Classification Soils were classified visually according to the Unified Soils Classification System (Sowers and Sowers, 1979). The soil classifications are shown on the Test Pit and Hand Auger Logs in Appendix B. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 12 Moisture-Densitv Relations The field moisture contents and field dry densities of relatively undisturbed soil samples were evaluated in the laboratory, in general accordance with ASTM D 2216 and ASTM D 2937. The results of these tests are shown on the Test Pit and Boring Logs in Appendix B. Expansion Potential Expansion index testing was performed on a representative sample of site soil in general accordance with ASTM D 4829. The results of expansion index testing are presented in the following table. Please note that the 2010 California Building Code (CBC) does not categorize soil expansion indices and as such, we have utilized these previous standards only to characterize the expansion potential ofthe tested sample. The results of expansion index testing are presented in the following table. SAMPLE LOCATION AND DEPTH (FT) EXPANSION INDEX EXPANSION POTENTIAL* TP-4 @ 0-7 (Composite) <5 Very Low * - per Table 18-I-B of the 2001 Galifornia Building Gode (International Conference of Building Officials, 2001) Atterberg Limits Tests were performed on a representative fine-grained soil sample to evaluate its liquid limit, plastic limit, and plasticity index (PI) in general accordance with ASTM D 4318. The test results indicate that the tested soil sample can exhibit plastic behavior. Test results are presented in the following table. SAMPLE LOCATION AND DEPTH (FT) PLASTIC LIMIT LIQUID LIMIT PLASTICITY INDEX HA-4 @ 1 VA-2 35 15 20 Particle - Size Analysis An evaluation was performed on a representative, soil sample in general accordance with ASTM D 422-63. The grain-size distribution curve is presented in Appendix D. The testing was utilized to evaluate the soil classification in accordance with the Unified Soil Classification System (USCS). The results ofthe particle size analysis indicate that the tested soil is a silty sand (SM). Miles-Pacific, LLC 2373 & 2375 Pio Pico Drive, Garlsbad Flle;wp12\6300\6324a.pge GeoSoils, Inc. w.o. 6324-A-SG October 31, 2012 Page 13 Saturated Resistivity, pH, and Soluble Sulfates, and Chlorides GSI conducted sampling of onsite earth materials for general soil corrosivity and soluble sulfates, and chlorides testing. The testing included evaluation of soil pH, soluble sulfates, chlorides, and saturated resistivity. Test results are presented in Appendix D and the following table: SAMPLE LOCATION AND DEPTH (FT) pH SATURATED RESISTIVITY (ohm-cm) SOLIUBLE SULFATES (ppm) SOLUBLE CHLORIDES (ppm) TP-1 @ 3 - 3V2 7.34 1,500 0.0330 102 Corrosion Summary Laboratory testing indicates that tested samples of the onsite soils are neutral to mildly alkaline with respectto soil acidity/alkalinity, are corrosive to exposed, buried metals when saturated, present negligible sulfate exposure to concrete, and are below the action level for chloride exposure (per State of California Department of Transportation, 2003). Reinforced concrete mix design for foundations, slab-on-grade floors, and pavements should minimally conform to "Exposure Class Cl" in Table 4.3.1 of ACI 318-08, as concrete would likely be exposed to moisture. It should be noted that GSI does not consult in the field of corrosion engineering. Therefore, additional comments and recommendations may be obtained from a qualified corrosion engineer based on the level of corrosion protection required for the project, as determined by the project architect and/or structural engineer. EMBANKMENT FACTORS (SHRINKAGE/BULKING) The volume change of excavated materials upon compaction as engineered fill is anticipated to vary with material type and location. The overall earthwork shrinkage and bulking may be approximated by using the following parameters: Undocumented Artificial Fill 5% to 10% shrinkage Quaternary Colluvium 5% to 10% shrinkage Weathered Paralic Deposits 3% to 8% shrinkage Unweathered Paralic Deposits 2% to 3% shrinkage/bulking It should be noted that the above factors are estimates only, based on preliminary data. Colluvium may achieve higher shrinkage if organics or clay content is higher than anticipated. Final earthwork balance factors could vary. In this regard, it is recommended that balance areas be reserved where grades could be adjusted up or down near the completion of grading in order to accommodate any yardage imbalance for the project. Miles-Pacific, LLC 2373 & 2375 Pio Pico Drive, Garlsbad Flle;wp12\6300\6324a.pge GeoSoils, Inc. w.o. 6324-A-SG October 31, 2012 Page 14 EXCAVATION FEASIBILITY Based on our experience with sites underlain by similar deposits, GSI anticipates that excavations into the onsite soils will range from easy to moderately difficult. However, localized cemented zones may be encountered and result in difficult excavation, especially if lightweight excavation equipment (i.e., backhoe, mini-excavator, etc.) is used. Excavation equipment should be appropriately sized to complete the planned excavations. PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS Based on our field exploration, laboratory testing, and geotechnical engineering analysis, it is our opinion that the site appears suitable for the proposed development from a geotechnical engineering and geologic viewpoint, provided that the recommendations presented in the following sections are properly incorporated into the design and construction phases of site development. The primary geotechnical concerns with respect to the currently proposed development are: Earth materials characteristics and depth to competent bearing material. • On-going expansion/corrosion potentials of site soils. Potential for perched groundwater to occur during and after development. Non-structural zone on un-mitigated perimeter conditions (improvements subject to distress). • Effects of the planned desilting basins on the stability and erosion of the cut slope descending to Interstate 5. • Temporary and permanent slope stability. • Regional seismic activity. The recommendations presented herein 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 conclusions and recommendations contained in this report shafl not be considered valid unless the changes are reviewed and the recommendations of this report are 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. 1. Geotechnical observation, and testing services should be provided during earthwork to aid the contractor in removing unsuitable soils and in his effort to compact the fill. 2. Geologic observations should be performed during any grading to verify and/or further evaluate geologic conditions. Although unlikely, if adverse geologic Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31,2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 15 structures are encountered, supplemental recommendations and earthwork may be warranted. 3. All undocumented fill, alluvium, colluvium and weathered portions ofthe younger paralic deposits are considered potentially compressible in their existing state and therefore, should not be relied upon forthe support of planned settlement-sensitive improvements (i.e., residential structures, underground utilities, walls, pavements, swimming pools/spas, etc.) and/or planned fills. These soils should be removed and re-used as properly compacted fill during grading. 4. In general, remedial grading excavations for the removal and re-compaction of potentially compressible, near-surface soils are anticipated to be on the order of 2 to 6y2 feet across a majority of the site. However, local deeper remedial grading excavations cannot be precluded and should be anticipated. Remedial grading excavations should be completed below a 1:1 (h:v) projection down from the bottom, outermost edge of proposed settlement-sensitive improvements and/or limits of planned fills unless constrained by property lines or existing structures to remain. 5. Laboratory testing indicates that the expansion index of a tested sample of the onsite earth materials is less than 5 which correlates to very low expansion potential. However, Atterberg limits testing indicates that the plasticity index of a tested sample of the onsite soils is 20 which may correspond to a moderate expansion potential. As such, some ofthe onsite soils are considered expansive per Section 1803.5.2 ofthe 2010 CBC. Based on visual soil classification during the field exploration and laboratory testing, expansive soil conditions are generally associated with the Quaternary-age paleosol exposed in Test Pit TP-1 as well as some near surface layers within the younger and older paralic deposits encountered in Hand Auger HA-4. Given the relatively limited horizontal and lateral extent of expansive soils when compared to the onsite soils exhibiting very low expansion characteristics, it is reasonable to believe that through proper soil blending during grading, finish grade soils will likely be non-detrimentally expansive. However, there is some potential that testing of finish grade soils may indicate the presence of detrimentally expansive soils. Thus on a preliminary basis, GSI is providing recommendations for conventional foundation designs as well as post-tension (PT) foundation systems, should expansive finish grade soils be present at the conclusion of grading. 6. Soil pH, saturated resistivity, soluble sulfate, and chloride testing indicates that a representative sample of the onsite soils is mildly to moderately alkaline with respect to soil acidity/alkalinity, is corrosive to exposed, buried metals when saturated, possesses negligible sulfate exposure to concrete, and is below the action level for chloride exposure (per State of California Department of Transportation, 2003). Reinforced concrete mix design for foundations, Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad ^ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 16 slab-on-grade floors, and pavements should minimally conform to "Exposure Class Cl" in Table 4.3.1 of ACI 318-08, as concrete would likely be exposed to moisture. GSI does not consult in corrosion engineering. Therefore, additional comments and recommendations may be obtained from a qualified corrosion engineer based on the level of corrosion protection desired or required for the project, as determined by the project architect and/or structural engineer. 7. In general and based upon the available data to date, regional groundwater is not expected to be encountered during construction ofthe proposed site improvements nor is it anticipated to adversely affect site development. However, there is potential for perched water conditions to manifest along zones of contrasting permeabilities (i.e., sandy/clayey fill lifts, fill/paralic deposits contacts, bedding, discontinuities, etc.) during and after construction. The potential for perched water to occur should be disclosed to all interested/affected parties. 8. It should be noted, that the 2010 CBC (CBSC, 2010) indicates that removals of unsuitable soils be performed across all areas to be graded, not just within the influence ofthe proposed residential structures. Relatively deep removals may also necessitate a special zone of consideration, on perimeter/confining areas. This zone would be approximately equal to the depth of removals, if removals cannot be performed onsite and offsite. For this site, the width of this zone is anticipated to be 2 to 6y2 feet, based on the available data. Any settlement-sensitive improvement (walls, brow ditches, curbs, streets, flatwork, etc.), constructed within this zone, may require deepened foundations, reinforcements, etc., or will retain some potential for settlement and associated distress. This will require proper disclosure to all interested/affected parties, should this condition exist at the conclusion of grading. Based on our review of BHA, Inc. (2012) and the available subsurface data, perimeter walls constructed near property lines at Lots 18 and 19 and along the southerly side of Street "A", near the eastern margin of the site should be deepened such that footings penetrate any potentially compressible soils, and are founded into unweathered paralic deposits. Based on the available subsurface data , this would require the retaining wall footings at the perimeter of the site to be on the order of 5 feet below finish grade for a minimum 1 foot embedment into unweathered paralic deposits. The perimeter brow ditch will likely retain some potential for settlement-related distress if it is not supported by unweathered paralic deposits. 9. Unsupported temporary excavation walls ranging between 4 and 20 feet in gross overall height should be constructed in accordance with CAL-OSHA guidelines for Type B soils, provided groundwater or running sands are not present. On a preliminary basis, unsupported temporary excavations walls may be constructed at gradients no steeper than 1:1 (horizontahvertical) provided groundwater and/or running sands are not present. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 17 10. The planned perimeter cut slopes will likely expose colluvium, weathered paralic deposits, and a local paleosol along the face of slope following construction. Due to insufficient space for corrective grading (i.e., stabilization), these slopes may retain some potential for erosion and sloughing. An erosion control mat such as MacMat-R (http://www.maccaferri.co.uk/PAGES00295.html) may be used to reduce erosion on perimeter cut slopes 5 feet or greater in overall height. Planned perimeter fill slopes greater than 5 feet in overall height where the removal and recompaction of potentially compressible soils cannot be completed below a 1:1 projection down from the toe ofthe sloe may experience some fill relaxation and settlement. Therefore, GSI recommends that foundations for any portion of the planned residential structures or pools/spas maintain a minimum horizontal distance of 10 feet as measured from the bottom outside edge of the foundation to the face ofthe descending fill slope. Flatwork or pavements located within H/3 feet from the tops of such fill slopes (where H is the height of the slope), may retain some potential for settlement-related distress. This should be disclosed to all interested/affected parties. 11. The seismicity-acceleration values provided herein should be considered during the design and construction ofthe proposed development. 12. General Earthwork and Grading Guidelines are provided at the end ofthis report as Appendix E. Specific recommendations are provided below. EARTHWORK CONSTRUCTION RECOMMENDATIONS General Remedial earthwork will be necessary for the support of the planned settlement-sensitive improvements (i.e., residential structures, walls, underground utilities, pavements, etc.). Remedial grading should conform to the guidelines presented in Appendix J of the 2010 CBC, the requirements ofthe City of Carlsbad, and the Grading Guidelines presented in Appendix E, except where specifically superceded in the text of this report. In case of conflict, the more onerous code or recommendations should govern. Prior to grading, a GSI representative should be present atthe pre-construction meeting to provide additional grading guidelines, if needed, and review the earthwork schedule. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 18 During earthwork construction, all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representative(s) of GSI. If unusual or unexpected conditions are exposed in thefield, they should be reviewed by this office and, if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act (OSHA), and the Construction Safety Act should be met. It is the onsite general contractor's and individual subcontractors' responsibility to provide a safe working environment for our field staff who are onsite. GSI does not consult in the area of safety engineering. GSI also recommends that the contractor(s) take precautionary measure to protect work, especially during the rainy season. Failure to do so may result in additional remedial earthwork. Demolition/Grubbing 1. Vegetation, and any miscellaneous deleterious debris generated from the demolition of existing site improvements should be removed from the areas of proposed grading/earthwork. 2. Cavities or loose soils remaining after demolition and site clearance should be cleaned out and observed by the geotechnical consultant. The cavities should be replaced with fill materials that have been moisture conditioned to at least optimum moisture content and compacted to at least 90 percent ofthe laboratory standard. 3. Any buried septic systems encountered during grading should be observed by the geotechnical consultant. Recommendationsforthe removal of septic structures will then be provided based on the conditions exposed. Remedial Removals (Removal of Potentially Compressible Surficial Materials) Where planned fills or settlement-sensitive improvements are proposed, potentially compressible undocumented artificial fill. Quaternary alluvium. Quaternary colluvium, Quaternary paleosol, and weathered paralic deposits should be removed to expose unweathered paralic deposits. Removed soils may be reused as properly engineered fill provided that major concentrations of organic and/or deleterious materials have been removed prior to placement. In general, the remedial grading excavations to remove potentially compressible soils are anticipated to be on the order of 2 to 6V2 feet across a majority ofthe site. However, local deeper remdial excavations cannot be precluded and should be anticipated. The removal of potentially compressible soils should be performed below a 1:1 (h:v) projection down from the bottom, outermost edge of proposed settlement-sensitive improvements and/or limits of planned fills. Once the unsuitable soils have been removed, the exposed paralic deposits should be scarified approximately 6 to 8 inches, moisture conditioned as necessary to achieve the soil's optimum moisture Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31,2012 Flle:wp12\6300\6324a.pge GcoSoilS, InC. Page 19 content and then be re-compacted to at least 90 percent ofthe laboratory standard prior to fill placement. All remedial removal excavations should be observed by the geotechnical consultant prior to scarification. Overexcavation BHA, Inc. (2012) indicates planned cut/fill transitions. As such, uniform support of foundations should be provided by overexcavating the cut portion of cut/fill transition lots or building pad areas where the planned plus remedial fill thickness does not allow for 2 feet of engineered fill beneath footings. This would require that all paralic deposits exposed within 2 feet of finish grade following the removal of potentially compressible soils be overexcavated to at least 2 feet below the lowermost foundation element (as approved by GSI field personnel) and be replaced with engineered fill compacted to at least 90 percent ofthe laboratory standard (ASTM D 1557). The bottom ofthe overexcavation should be sloped toward the street, scarified at least 6 to 8 inches, moisture-conditioned as necessary to achieve the soil's optimum moisture content, and then be recompacted to at least 90 percent of the laboratory standard prior to fill placement. Overexcavation should be laterally completed to at least 5 feet outside the outermost foundation element of settlement-sensitive improvements. Overexcavations should be observed by the geotechnical consultant prior to scarification. The maximum to minimum fill thickness across building pads should not exceed a ratio of 3:1 (maximum:minimum). Overexcavation need not be performed in street areas. Temporary Slopes Temporary slopes for excavations greaterthan 4 feet but less than 20 feet in overall height should conform to CAL-OSHA and/or OSHA requirements for Type "B" soils. Temporary slopes, up to a maximum height of ±20 feet, may be excavated at a 1:1 (h:v) gradient, or flatter, provided groundwater and/or running sands are not exposed. Construction materials or soil stockpiles should not be placed within 'H' of any temporary slope where 'H' equals the height of the temporary slope. All temporary slopes should be observed by a licensed engineering geologist and/or geotechnical engineer priorto worker entry into the excavation. Based on the exposed field conditions, inclining temporary slopes to flatter gradients or the use of shoring may be necessary if adverse conditions are observed. If temporary slopes conflict with property boundaries, shoring or alternating slot excavations may be necessary. The need for shoring or alternating slot excavations could be further evaluated during the grading plan review stage, but is considered likely on the eastern and northern property lines. Engineered Fill Placement Engineered fill should be well blended, placed in thin lifts, moisture conditioned, and mixed to achieve 1.1 to 1.2 times the soil's optimum moisture content, and then be mechanically compacted to at least 90 percent of the laboratory standard (ASTM D 1557). Engineered Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31,2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 20 fill placement should be observed and selectively tested for moisture content and compaction by the geotechnical consultant. Graded Slopes At this time maximum graded (cut and fill) slopes are anticipated to be ±6 and ±8 feet, respectively, in overall height and inclined at gradients no steeper than 2:1 (h:v). It is our professional opinion that graded fill slopes will be grossly and surficially stable following the completion of construction provided that site drainage is directed away from the tops of slopes and the slope faces are protected with deep-rooted vegetative cover capable of surviving the prevailing climate without only the amount of irrigation water necessary to sustain plant vigor. Graded cut slopes will likely expose colluvium, weathered younger paralic deposits, and possibly a paleosol along the face at the conclusion of construction. GSI recommends that any "in-tract" cut slope or cut-over-fill slope receive stabilization (see Appendix E) and/or be constructed as a fill slope. Due to insufficient space for stabilization along the perimeter ofthe site, it is our opinion that cut slopes exposing these conditions will be more readily subject to erosion and sloughing. An erosion control mat such as MacMat-R (http://www.maccaferri.co.uk/PAGES00295.html) may be used to reduce erosion on perimeter cut slopes 5 feet or greater in overall height. Vegetative cover should be provided as soon as possible following slope construction. In the interim, GSI recommends the slope faces be covered with City of Carlsbad approved erosion control devices. Graded slope stability should be further evaluated during the grading plan review stage. Graded fill slopes should be properly keyed and benched, and be compacted to at least 90 percent relative compaction throughout, including the slope face. All graded cut slopes should be observed by this office following construction. If adverse geologic conditions (daylighted, out-of-slope bedding and/or joints/fractures, highly weathered paralic deposits, thick unsuitable soils, etc.) are noted in the slope face, GSI would provide recommendations for mitigation. Mitigation measures may included but not necessarily be limited to inclining the slope to gradients flatter than any adverse geologic structure, stabilization fills, or the use of an erosion control mat. Import Fill Materials Any import fill materials used on this project should possess an E.I. of 20 or less with a P.I. not exceeding 15. All import fill material should be tested by GSI priorto placement within the site. GSI would also request environmental documentation (e.g.. Phase I Environmental Site Assessment) pertaining to offsite export site, to evaluate ifthe proposed import could present an environmental risk to the planned residential development. At least three (3) business days of lead time will be necessary for the required laboratory testing and document review. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31, 2012 File:wp12\6300\6324a.pge GeoSOllS, InC. Page 21 PRELIMINARY FOUNDATION RECOMMENDATIONS General Thefoundation design and construction recommendations are based on laboratory testing and engineering evaluations of onsite earth materials by GSI. The following preliminary foundation construction recommendations are presented as a minimum criteriafrom a soi Is engineering viewpoint. Testing indicates that the expansion index of the representative majority of onsite soils is <5. However, Atterberg Limits testing suggests that some thin localized layers of paralic deposits may be moderately expansive (expansion index = 51 to 90). Provided that sufficient blending of sands and clays is undertaken during fill placement, GSI anticipates that finish grade soils will be non-detrimentally expansive (i.e., expansion index less than 21 and a plasticity index [PI] less than 15). However, there is some likelihood that detrimentally expansive soils may be detected in finish grade soils at the conclusion of site grading. As such, GSI is providing preliminary design and construction recommendations for conventional foundation recommendations for non-detrimentally expansive soil conditions as well as post-tensioned foundation recommendations for detrimental lowto medium expansive soil conditions (i.e., soils with an expansion index = 21 to 90 and with a PI = 15 or greater). In addition, GSI is providing post-tension foundation systems for non-detrimentally expansive soil conditions if higher foundation performance is expected. This report presents minimum design criteria for the design of foundations, concrete slab-on-grade floors, and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer. Recommendations by the project's design-structural engineer or architect, which may exceed the geotechnical consultant's recommendations, should take precedence overthe following minimum requirements. Thefoundation systems recommended herein may be used to support the proposed residences provided they are entirely founded in compacted fill tested and approved by GSI. The proposed foundation systems should be designed and constructed in accordance with the guidelines contained in the 2010 CBC. In the event that the information concerning the proposed development plan is not correct, or any changes in the design, location or loading conditions of the proposed structure are made, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. The information and recommendations presented in this section are not meant to supercede design by the project structural engineer or civil engineer specializing in structural design. Upon request, GSI could provide additional input/consultation regarding soil parameters, as they relate to foundation design. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 22 General Foundation Design 1. The foundation systems should be designed and constructed in accordance with guidelines presented in the 2010 CBC. 2. An allowable bearing value of 1,500 pounds per square foot (psf) may be used for the design of footings that maintain a minimum width of 12 inches and a minimum depth of 12 inches (belowthe lowest adjacent grade) and are founded into properly engineered fill. This value may be increased by 20 percent for each additional 12 inches in footing depth to a maximum value of 2,500 psf. These values may be increased by one-third when considering short duration seismic or wind loads. Isolated pad footings should have a minimum dimension of at least 24 inches square and a minimum embedment of 24 inches below the lowest adjacent grade into properly engineered fill. Foundation embedment excludes any landscaped zone, topsoil/colluvium, weathered paralic deposits, concrete slabs-on-grade, and/or slab underlayment. 3. Passive earth pressure may be computed as an equivalent fluid having a density of 150 pcf, with a maximum earth pressure of 1,500 psf for footings founded into properly engineered fill. Lateral passive pressures for shallow foundations within 2010 CBC setback zones should be reduced following a review bythe geotechnical engineer unless proper setback can be established. 4. For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. 5. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 6. All footing setbacks from slopes should comply with Figure 1808.7.1 of the 2010 CBC. GSI recommends a minimum horizontal setback distance of 7 feet as measured from the bottom, outboard edge ofthe footing to the slope face. 7. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1:1 projection from the heel ofthe wall. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances as described in the "Retaining Wall" section ofthis report. 8. Code-compliant foundations may be conventional-type if soils within the influence of the foundation have an E.I. of 20 or less and a P.I. less than 15. Otherwise post- tension foundation systems should be used. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 23 Foundation Settlement Provided the recommendations in this report are properly followed, foundation systems should be minimally designed to accommodate a differential settlement of at least % inch in a 40-foot horizontal span (angular distortion = 1/360). PRELIMINARY FOUNDATION CONSTRUCTION RECOMMENDATIONS The following foundation construction recommendations are presented as a minimum criteria from a soils engineering viewpoint. Conventional foundations may be used to support the planned residential structures provided the soils within the upper 7 feet of pad grade possess an E.I. of 20 or less and a P.I. less than 15. Otherwise, post-tension foundations would be necessary to mitigate expansive soil effects in accordance with Sections 1808.6.1 or 1808.6.2 ofthe 2010 CBC. Conventional Foundations (Expansion Index of 20 or Less with a Plasticity Index Less Than 15) 1. Exterior and interior footings should be founded into engineered fill at a minimum depth of 12 or 18 inches below the lowest adjacent grade for a one- or two-story floor loads, respectively. For one- and two-story floor loads, footing widths should be 12 and 15 inches, respectively. Isolated, exterior column and panel pads, or wall footings, should be at least 24 inches, square, and founded at a minimum depth of 24 inches into properly compacted fill. All footings should be minimally reinforced with four No. 4 reinforcing bars, two placed near the top and two placed near the bottom of the footing. 2. All interior and exterior column footings, and perimeter wall footings, should be tied together via grade beams in at least one direction. The grade beam should be at least 12 inches square in cross section, and should be provided with a minimum of one No.4 reinforcing bar at the top, and one No.4 reinforcing bar at the bottom of the grade beam. The base of the reinforced grade beam should be at the same elevation as the adjoining footings. 3. A grade beam, reinforced as previously recommended and at least 12 inches square, should be provided across large (garage) entrances. The base of the reinforced grade beam should be at the same elevation as the adjoining footings. 4. A minimum concrete slab-on-grade thickness of 5 inches is recommended. 5. Concrete slabs should be reinforced with a minimum of No. 3 reinforcement bars placed at 18-inch on centers, in two horizontally perpendicular directions (i.e., long axis and short axis). Miles-Pacific, LLC W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a,pge GeoSoilS, InC. Page 24 6. All slab reinforcement should be supported to ensure proper mid-slab height positioning during placement ofthe concrete. "Hooking" of reinforcement is not an acceptable method of positioning. 7. Specific slab subgrade pre-soaking is not required for these soil conditions. However, moisture conditioning the upper 12 inches ofthe slab subgrade to at least optimum moisture should be considered. 8. Soils generated from footing excavations to be used onsite should be compacted to a minimum relative compaction of 90 percent of the laboratory standard (ASTM D 1557), whether the soils are to be placed inside the foundation perimeter or in the yard/right-of-way areas. This material must not alter positive drainage patterns that direct drainage away from the structural areas and toward the street. 9. Reinforced concrete mix design should conform to "Exposure Class Cl" in Table 4.3.1 of ACI-318-08 since concrete would likely be exposed to moisture. Post-Tensioned Foundations Post-tension foundations may be used to mitigate the damaging effects of expansive soils on the planned building's foundation and slab-on-grade floor if such soil condition are encountered at finish grade. They may also be used for increased performance of foundations constructed on non-detrimentally expansive soils. The post-tension foundation designer may elect to exceed these minimal recommendations to increase slab stiffness performance. Post-tension (PT) design may be either ribbed or mat-type. The latter is also referred to as uniform thickness foundation (UTF). The use of a UTF is an alternative to the traditional ribbed-type. The UTF offers a reduction in grade beams (i.e., that method typically uses a single perimeter grade beam and possible "shovel" footings), but has a thicker slab than the ribbed-type. The information and recommendations presented in this section are not meant to supercede design by a registered structural engineer or civil engineer qualified to perform post-tensioned design. Post-tensioned foundations should be designed using sound engineering practice and be in accordance with local and 2010 CBC requirements. Upon request, GSI can provide additional data/consultation regarding soil parameters as related to post-tensioned foundation design. From a soil expansion/shrinkage standpoint, a common contributing factor to distress of structures using post-tensioned slabs is a "dishing" or "arching" ofthe slabs. This is caused by the fluctuation of moisture content in the soils below the perimeter of the slab primarily due to onsite and offsite irrigation practices, climatic and seasonal changes, and the presence of expansive soils. When the soil environment surrounding the exterior of the slab has a higher moisture content than the area beneath the slab, moisture tends to migrate inward, underneath the slab edges to a distance beyond the slab edges referred Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31,2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 25 to as the moisture variation distance. When this migration of water occurs, the volume of the soils beneath the slab edges expand and cause the slab edges to lift in response. This is referred to as an edge-lift condition. Conversely, when the outside soil environment is drier, the moisture transmission regime is reversed and the soils underneath the slab edges lose their moisture and shrink. This process leads to dropping ofthe slab at the edges, which leads to what is commonly referred to as the center lift condition. A well-designed, post-tensioned slab having sufficient stiffness and rigidity provides a resistance to excessive bending that results from non-uniform swelling and shrinking slab subgrade soils, particularly within the moisture variation distance, near the slab edges. Other mitigation techniques typically used in conjunction with post-tensioned slabs consist of a combination of specific soil pre-saturation and the construction of a perimeter "cut-off" wall grade beam. Soil pre-saturation consists of moisture conditioning the slab subgrade soils prior to the post-tension slab construction. This effectively reduces soil moisture migration from the area located outside the building toward the soils underlying the post-tension slab. Perimeter cut-off walls are thickened edges of the concrete slab that impedes both outward and inward soil moisture migration. Soil Moisture Specific pre-moistening and moisture testing ofthe slab subgrade is recommended for expansive soil conditions (expansion index [E.I.] > 20 and P.I. of 15 or greater). The moisture content of the subgrade soils should be equal to, or greater than optimum moisture to a depth equivalent to the exterior footing depth in the slab areas (typically 12 and 18 inches for very low to low [E.I. 0 to 50] and medium [E.I. = 51 to 90] expansive soils, respectively). Pre-moistening and/or pre-soaking should be evaluated bythe soils engineer 72 hours prior to vapor retarder placement. Perimeter Cut-Off Walls Perimeter cut-off walls should be 12 and 18 inches deep for very low to low and medium expansive soil conditions, respectively. The cut-off walls may be integrated into the slab design or independent of the slab. The cut-off walls should be a minimum of 6 inches thick. The bottom ofthe perimeter cut-off wall should be designed to resist tension, using cable or reinforcement per the structural engineer. Post-Tensioned Foundation Design The following recommendations for design of post-tensioned slabs have been prepared in general compliance with the requirements of the recent Post Tensioning Institute's (PTI's) publication titled "Design of Post-Tensioned Slabs on Ground, Third Edition" (PTI, 2004), together with it's subsequent addendums (PTI, 2008). Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GCOSoilS, IttC. Page 26 Soil Support Parameters The recommendations for soil support parameters have been provided based on the typical soil index properties for soils that are very low to medium in expansion potential. The soil index properties are typically the upper bound values based on our experience and practice in the southern California area. The following table presents suggested minimum coefficients to be used in the Post-Tensioning Institute design method. Thornthwaite Moisture Index -20 inches/year Correction Factor for Irrigation 20 inches/year Depth to Constant Soil Suction 7 feet Constant soil Suction (pf) 3.6 Moisture Velocity 0.7 inches/month Plasticitv Index (P.I.) 15-35 Based on the above, the recommended soil support parameters are tabulated below: DESIGN PARAMETERS VERY LOW TO LOW EXPANSION (El = 0-50L MEDIUM EXPANSION (El = 51-90) e^ center lift 9.0 feet 8.7 feet e„ edge lift 5.2 feet 4.5 feet y^ center lift 0.3 inches 0.49 inches ym edge lift 0.7 inch 1.3 inch Bearing Value 1,000 psf 1,000 psf Lateral Pressure 250 psf 175 psf Subgrade Modulus (k) 100 pci/inch 85 pci/inch Minimum Perimeter Footing Embedment 12 inches 18 inches Internal bearing values within the perimeter ofthe post-tension slab may be increased to 1,500 psf for a minimum embedment of 12 inches, then by 20 percent for each additional foot of embedment to a maximum of 2,500 psf (fill). As measured below the lowest adjacent compacted subgrade surface without landscape layer or sand underlayment. Note: The use of open bottomed raised planters adjacent to foundations will require more onerous desiqn parameters. Miles-Pacific, LLC 2373 & 2375 Pio Pico Drive, Garlsbad File:wp12\6300\6324a.pge GeoSoils, Inc. w.o. 6324-A-SG October 31, 2012 Page 27 The parameters are considered minimums and may not be adequate to represent all expansive soils/drainage conditions such as adverse drainage and/or improper landscaping and maintenance. The above parameters are applicable provided the structure has positive drainage that is maintained away from the structure. In addition, no trees with significant root systems are to be planted within 15 feet of the perimeter of foundations. Therefore, it is important that information regarding drainage, site maintenance, trees, settlements, and effects of expansive soils be passed on to future all interested/affected parties. The values tabulated above may not be appropriate to account for possible differential settlement of the slab due to other factors, such as excessive settlements. If a stiffer slab is desired, alternative Post-Tensioning Institute ([PTI] third edition) parameters may be recommended. CORROSION Upon completion of grading, additional testing of soils (including import materials) for corrosion to concrete and metals should be performed priorto the construction of utilities and foundations. SOIL MOISTURE TRANSMISSION CONSIDERATIONS GSI has evaluated the potential for vapor or water transmission through the concrete floor slab, in light of typical floor coverings and improvements. Please note that slab moisture emission rates range from 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 limit. The recommendations in this section are not intended to preclude the transmission of water or vapor through the foundation or slabs. Foundation systems and slabs shall not allow water or water vapor to enter into the structure so as to cause damage to another building component or to limit the installation of the type of flooring materials typically used for the particular application (State of California, 2011). These recommendations may be exceeded or supplemented by a water "proofing" specialist, project architect, or structural consultant. Thus, the client will need to evaluate the following in light of a cost vs. benefit analysis (owner expectations and repairs/replacement), along with disclosure to all interested/affected parties. It should also be noted that vapor transmission will occur in new slab-on-grade floors as a result of chemical reactions taking place within the curing concrete. Vapor transmission through concrete floor slabs as a result of concrete curing has the potential to adversely affect sensitive floor coverings depending on the thickness of the concrete floor slab and the duration of time between the placement of concrete, and the floor covering. It is possible that a slab moisture sealant may be needed prior to the placement of sensitive floor coverings if a thick slab-on-grade floor is used and the time frame between concrete and floor covering placement is relatively short. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 28 Considering the E.I. test results presented herein, and known soil conditions in the region, the anticipated typical water vapor transmission rates, floor coverings, and improvements (to be chosen by the Client and/or project architect) that can tolerate vapor transmission rates without significant distress, the following alternatives are provided: • Concrete slabs should be a minimum of 5 inches thick. • Concrete slab underlayment should consist of a 10 to 15-mil vapor retarder, or equivalent, with all laps sealed per the 2010 CBC 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 and ASTM E 1643. The 10 to 15-mil vapor retarder (ASTM E 1745 - Class A or B) shall be installed per the recommendations of the manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). Concrete slabs, including the garage areas, shall be underlain by 2 inches of clean, washed sand (SE > 30) above a 15 mil vapor retarder (ASTM E-1745 - Class A or Class B, per Engineering Bulletin 119 [Kanare, 2005]) installed per the recommendations ofthe manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). The manufacturer shall provide instructions for lap sealing, including minimum width of lap, method of sealing, and either supply or specify suitable products for lap sealing (ASTM E 1745), and per code. ACI 302.1 R-04 (2004) states "If a cushion or sand layer is desired between the vapor retarder and the slab, care must be taken to protect the sand layer from taking on additional water from a source such as rain, curing, cutting, or cleaning. Wet cushion or sand layer has been directly linked in the past to significant lengthening of time required for a slab to reach an acceptable level of dryness for floor covering applications." Therefore, additional observation and/ortesting will be necessary for the cushion or sand layer for moisture content, and relatively uniform thicknesses, prior to the placement of concrete. The vapor retarder shall be underlain by 2 inches of sand (SE >^ 30) placed directly on the prepared, moisture conditioned, subgrade and should be sealed to provide a continuous retarder under the entire slab, as discussed above. As discussed previously, GSI indicated this layer of import sand may be eliminated below the vapor retarder, if laboratory testing indicates that the slab subgrade soil have a sand equivalent (SE) of 30 or greater. Concrete should have a maximum water/cement ratio of 0.50. This does not supercede Table 4.3.1 of Chapter 4 of the ACI (2008) for corrosion or other corrosive requirements. Additional concrete mix design recommendations should be provided by the structural consultant and/or waterproofing specialist. Concrete Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoilS, Inc. October 31, 2012 File:wp12\6300\6324a.pge Page 29 finishing and workablity should be addressed by the structural consultant and a waterproofing specialist. Where slab water/cement ratios are as indicated herein, and/or admixtures used, the structural consultant should also make changes to the concrete in the grade beams and footings in kind, so that the concrete used in the foundation and slabs are designed and/or treated for more uniform moisture protection. Theowner(s) should be specifically advised which areas are suitable tortile flooring, vinyl flooring, or other types of water/vapor-sensitive flooring and which are not suitable. In all planned floor areas, flooring shall be installed perthe manufactures recommendations. • Additional recommendations regarding water or vapor transmission should be provided by the architect/structural engineer/slab or foundation designer and should be consistent with the specified floor coverings indicated by the architect. Regardless ofthe mitigation, some limited moisture/moisture vapor transmission through the slab should be anticipated. Construction crews may require special training for installation of certain product(s), as well as concrete finishing techniques. The use of specialized product(s) should be approved by the slab designer and water-proofing consultant. Atechnical representative ofthe flooring contractor should reviewthe slab and moisture retarder plans and provide comment priorto the construction of the foundations or improvements. The vapor retarder contractor should have representatives onsite during the initial installation. WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS Conventional Retaining Walls The design parameters provided below assume that either very low expansive soils (typically Class 2 permeable filter material or Class 3 aggregate base) or native onsite materials with an expansion index up to 50 are used to backfill any retaining wall. 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. The foundation system forthe 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 the lowest adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no increase in bearing forfooting width. As indicated previously, planned retaining wall footings near the perimeter ofthe site will likely need to be deepened into unweathered paralic deposits for adequate vertical and lateral bearing support. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoils, Inc. October 31, 2012 File:wp12\6300\6324a.pge Page 30 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 55 pounds per cubic foot (pcf) and 65 pcf for select and very low to low expansive native backfill, respectively. The design should include any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 10 feet high. Design parameters for walls less than 3 feet in height may be superceded by City of Carlsbad and/or County of San Diego standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. For preliminary planning purposes, the structural consultant should incorporate the surcharge of traffic on the back of retaining walls. The traffic surcharge may be taken as 100 psf/ft in the upper 5 feet of backfill for light truck and cars traffic within "H" feet from the back of the wall, where "H" equals the wall height. This does not include the surcharge of parked vehicles which should be evaluated at a higher surcharge to account for the effects of seismic loading. SURFACE SLOPE OF RETAINED MATERIAL (HORIZONTAL:VERTICAL) EQUIVALENT FLUID WEIGHT P.C.F. (SELECT BACKFILL)*^* EQUIVALENT FLUID WEIGHT P.C.F. (NATIVE BACKFILL)'^' Level*^' 2 to 1 45 65 55 70 Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without a slope for a distance of 2H behind the wall, where H is the height of the wall. SE > 30, P.I. < 15, E.I. < 21, and <^ 10% passing No. 200 sieve. E.I. = 0 to 50, SE > 30, P.I. < 15, E.I. < 21, and < 15% passing No. 200 sieve. Miles-Pacific, LLC 2373 & 2375 Pio Pico Drive, Carlsbad File:wp12\6300\6324a.pge GeoSoils, Inc. W.O. 6324-A-SG October 31, 2012 Page 31 Seismic Surcharge For engineered retaining walls, GSI recommends that the walls be evaluated for a seismic surcharge (in general accordance with 2010 CBC requirements). The site walls in this category should maintain an overturning Factor-of-Safety (FOS) of approximately 1.25 when the seismic surcharge (increment), is applied. For restrained walls, the seismic surcharge should be applied as a uniform surcharge load from the bottom ofthe footing (excluding shear keys) to the top ofthe backfill atthe heel ofthe wall footing. This seismic surcharge pressure (seismic increment) may be taken as 15H where "H" for retained walls is the dimension previously noted as the height of the backfill to the bottom of the footing. The resultant force should be applied at a distance 0.6 H up from the bottom ofthe footing. For the evaluation of the seismic surcharge, the bearing pressure may exceed the static value by one-third, considering the transient nature of this surcharge. For cantilevered walls the pressure should be an inverted triangular distribution using 15H. Reference for the seismic surcharge is Section 1802.2 of the 2010 CBC. Please note this is for local wall stability only. The 15H is derived from a Mononobe-Okabe solution for both restrained cantilever walls. This accounts for the increased lateral pressure due to shakedown or movement ofthe sand fill soil in the zone of influence from the wall or roughly a 45° - c|)/2 plane away from the back ofthe wall. The 15H seismic surcharge is derived from the formula: P, = %.aH.y,H Where: Pi, = Seismic increment = Probabilistic horizontal site acceleration with a percentage of "g" Yt = total unit weight (115 to 125 pcf for site soils @ 90% relative compaction. H = Heightofthe wall from the bottom ofthe footing or point of pile fixity. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the backdrainage 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 iy2-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For select 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 E.I. = 50, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited Miles-Pacific, LLC W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoils, InC. October 31, 2012 Flle:wp12\6300\6324a.pge Page 32 Structural footing or settlement-sensitive improvement (1) Waterproofing membrane CMU or reinforced-concrete wall \— Proposed grade \ sloped to drain \ per precise civil \ drawings \ (5) Weep hole Footing and wall design by others-^^ Native backfill 11 (h-v) or flatter backcut to be properly benched (6) Footing (1) Waterproofing membrane. (2) Gravel: Clean, crushed, % to 1>2 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 (perforations down). (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Footing: |f 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. Ge^S&iMSf Inc. RETAINING WALL DETAIL - ALTERNATIVE A Detail 1 (1) Waterproofing membrane (optional) CMU or reinforced-concrete wall Structural footing or settlement-sensitive improvement Footing and wall design by others—-^^^ (5) Weep hole Proposed grade sloped to drain per precise civil drawings Native backfill 1:1 (h:v) or flatter backcut to be properly benched (6) 1 cubic foot of %-inch crushed rock (7) Footing (1) Waterproofing membrane (optional): Liquid boot or approved mastic equivalent. (2) Drain: Miradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls; Miradrain 6200 or J-drain 200 or equivalent for waterproofed walls (all perforations down). (3) Filter fabric: Mirafi MON or approved equivalent; place fabric flap behind core. (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down). (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Gravel: Clean, crushed, % to 1>2 inch. (7) Footing: |f 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. GeoSoiixy Inc. RETAINING WALL DETAIL - ALTERNATIVE B Detail 2 (1) Waterproofing membrane CMU or reinforced-concrete wall Structural footing or settlement-sensitive improvement Provide surface drainage 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 1)^ 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 to proper outlet point (perforations down). (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Clean sand backfilh 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 backfilh If E.I. (21 and S.E. >35 then all sand requirements also may not be required and will be reviewed by the geotechnical consultant. RETAINING WALL DETAIL - ALTERNATIVE C Detail 3 access and confined areas, (panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an expansion index (E.I.) potential of greaterthan 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-inch diameter solid PVC or ABS pipe spaced no greater than ± 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes, only, in walls higher than 2 feet, is not recommended. The surface ofthe backfill should besealed by pavement or the top 18 inches compacted with native soil (E.I. < 50). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase ofthe 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 ofthe transition may be accommodated. Expansion joints should be placed no greater than 20 feet on-center, in accordance with the structural engineer's/wall designer's recommendations, regardless of whether or nottransition conditions exist. Expansion joints should be sealed with aflexible, non-shrink grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS Expansive Soils and Slope Creep Some ofthe soils at the site are likely to be expansive and therefore, become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoils, InC. October 31, 2012 File:wp12\6300\6324a.pge Page 36 seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth ofthese shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 10 feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences/walls. Where removal and recompaction of potentially compressible soils below a 1:1 (h:v) projection down from the toe of perimeter fill slopes are constrained by property lines, improvements located within about H/3 feet from the tops of fill slopes, where H is the height ofthe slope, may be adversely affected by creep. This influence is normally in the form of detrimental settlement, and tilting ofthe proposed improvements. The dessication/swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to all interested/affected parties. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 10 feet, some settlement and tilting of the walls/fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be constructed on a combination of grade beam and caisson foundations. The grade beam should be at a minimum of 12 inches by 12 inches in cross section, supported by drilled caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet on center, and with a minimum embedment length of 7 feet below the bottom ofthe grade beam. The strength of the concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons should be in accordance with the recommendations ofthe project structural engineer, and include the utilization ofthe following geotechnical parameters: Creep Zone: 5-foot vertical zone below the slope face and projected upward parallel to the slope face. Creep Load: The creep load projected on the area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad GcoSoilS, InC. October 31, 2012 Flie:wp12\6300\6324a.pge Page 37 Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive Resistance: Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, to a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution ofthe creep prone zone above the point of fixity, to passive resistance, should be disregarded. Allowable Axial Capacity: Shaft capacity : 350 psf applied below the point of fixity over the surface area of the shaft. Tip capacity: 4,500 psf. EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS Some ofthe soil materials on site are likely to be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify all interested/affected parties of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. The moisture content ofthe subgrade should be proof tested within 72 hours prior to pouring concrete. 2. Concrete slabs should be cast over a relatively non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. The layer should wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Carlsbad GeoSoils, InC. October 31, 2012 File;wp12\6300\6324a.pge Page 38 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. The exterior slabs should be scored or saw cut, y2 to % inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. 6. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including post-construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner or homeowners association. 12. Due to expansive soils, air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 39 flexible couplings for plumbing and electrical lines. A/C waste water lines should be drained to a suitable non-erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. PRELIMINARY PAVEMENT DESIGN New Pavements New asphaltic concrete pavement sections were analyzed using an assumed R-value and an assumed traffic index (T.l.) value. For preliminary planning purposes, the following AC pavement structural sections are provided in the following table. Final pavement structural sections should be based on R-value testing of soils exposed near the subgrade elevation following grading and underground utility construction. New Asphaltic Concrete (AC) Pavement NEW ASPHALTIC CONCRETE PAVEMENT TRAFFIC AREA T.l.'^' SUBGRADE R-VALUE A.C. THICKNESS (inches) CLASS 2 AGGREGATE BASE THICKNESS'^^ (inches) Residential Street 5.5 30 3.0 7.5 '^'TI values have been assumed for planning purposes herein and should be confirmed by the design team during future plan development. '^'Denotes standard Caltrans Glass 2 aggregate base R >78, SE >22). The recommended pavement sections provided above are meant as minimums. If thinner or highly variable pavement sections are constructed, increased maintenance and repair could be expected. If the ADT (average daily traffic) beyond that intended, as reflected by the traffic index used for design, increased maintenance and repair could be required for the pavement section. Best management construction practices should be in effect at all times. Miles-Pacific, LLC 2373 & 2375 Pio Pico Drive, Garlsbad File:wp12\6300\6324a.pge GeoSoils, Inc. w.o. 6324-A-SC October 31, 2012 Page 40 Pavement Grading Recommendations General Subgrade preparation and aggregate base preparation should be performed in accordance with the recommendations presented below, and the minimum subgrade (upper 12 inches) and Class 2 aggregate base compaction should generally be 95 percent ofthe maximum dry density (ASTM D 1557). If adverse conditions (i.e., saturated ground, etc.) are encountered during preparation of subgrade, special construction methods may need to be employed. These recommendations should be considered preliminary. Further R-value testing and pavement design analysis should be performed upon completion of grading and underground utility trench backfill. All section changes should be properly transitioned. If adverse conditions are encountered during the preparation of subgrade materials, special construction methods may need to be employed. Subgrade Within street areas, all surficial deposits of loose soil material generated underground utility construction should be removed or re-compacted as recommended. After the loose soils are removed, the exposed ground should be scarified to a depth of 12 inches, moisture conditioned as necessary and compacted to 95 percent of maximum laboratory density, as determined by ASTM Test Method D 1557. Deleterious material, excessively wet or dry pockets, concentrated zones of oversized rock fragments, and any other unsuitable materials encountered during roadway grading should be removed. The compacted fill material should then be brought to the elevation of the proposed subgrade for the pavement. The subgrade should be proof-rolled in order to ensure a uniformly firm and unyielding surface. All grading and fill placement should be observed by the project soil engineer and/or his representative. Aggregate Base Compaction tests are required for the recommended aggregate base section. The minimum relative compaction required will be 95 percent of the maximum laboratory density as determined by ASTM Test Method D 1557. Base aggregate should be in accordance to the "Standard Specifications for Public Works Construction" (green book) current edition. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad , October 31, 2012 File;wp12\6300\6324a.pge GeoSoilS, InC. Page 41 Paving Prime coat may be omitted if all ofthe following conditions are met: 1. The asphalt pavement layer is placed within two weeks of completion of base and/or sub base course. 2. Traffic is not routed over completed base before paving. 3. Construction is completed during the dry season of May through October. 4. The base is free of dirt and debris. If construction is performed during the wet season of November through April, prime coat may be omitted if no rain occurs between completion of base course and paving and the time between completion of base and paving is reduced to three days, provided the base is free of dirt and debris. Where prime coat has been omitted and rain occurs, traffic is routed over base course, or paving is delayed, measures shall be taken to restore base course, subbase course, and subgrade to conditions that will meet specifications as directed by the soil engineer. Drainage Positive drainage should be provided for all surface water to drain towards an approved drainage facility. Positive site drainage should be maintained at all times. Water should not be allowed to pond or seep into the ground. If planters or landscaping are adjacent to paved areas, measures should be taken to minimize the potential for water to enter the pavement section. These measures may include, but not limited to, subdrainage devices, thickened curbs, or concrete cut-off walls. ONSITE INFILTRATION-RUNOFF RETENTION SYSTEMS General Should onsite infiltration-runoff retention systems (OIRRS) be planned for Best Management Practices (BMP's) or Low Impact Development (LID) principles for the project, some guidelines should/must be followed in the planning, design, and construction of such systems. Such facilities, if improperly designed or implemented without consideration of the geotechnical aspects of site conditions, can contribute to flooding, saturation of bearing materials beneath site improvements, slope instability, and possible concentration and contribution of pollutants into the groundwater or storm drain and/or utility trench systems. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 42 A key factor in these systems is the infiltration rate (often referred to as the percolation rate) which can be ascribed to, or determined for, the earth materials within which these systems are installed. Additionally, the infiltration rate ofthe designed system (which may include gravel, sand, mulch/topsoil, or other amendments, etc.) will need to be considered. The project infiltration testing is very site specific, any changes to the location of the proposed OIRRS and/or estimated size of the OIRRS, may require additional infiltration testing. Locally, relatively impermeable formations include: paralic deposits, claystone, siltstone, cemented sandstone, igneous and metamorphic bedrock, as well as expansive fill soils. Some of the methods which are utilized for onsite infiltration include percolation basins, drywells, bio-swale/bio-retention, permeable pavers/pavement, infiltration trenches, filter boxes and subsurface infiltration galleries/chambers. Some of these systems are constructed using native and import soils, perforated piping, and filter fabrics while others employ structural components such as stormwater infiltration chambers and filters/separators. Every site will have characteristics which should lend themselves to one or more ofthese methods; but, not every site is suitable for OIRRS. In practice, OIRRS are usually initially designed bythe project design civil engineer. Selection of methods should include (but should not be limited to) review by licensed professionals including the geotechnical engineer, hydrogeologist, engineering geologist, project civil engineer, landscape architect, environmental professional, and industrial hygienist. Applicable governing agency requirements should be reviewed and included in design considerations. The following geotechnical guidelines should be considered when designing onsite infiltration-runoff retention systems: It is not good engineering practice to allow water to saturate soils, especially near slopes or improvements; however, the controlling agency/authority is now requiring this for OIRRS purposes on many projects. If infiltration is planned, infiltration system design should be based on actual infiltration testing results/data, preferably utilizing double-ring infiltrometer testing (ASTM D 3385) to determine the infiltration rate of the earth materials being contemplated for infiltration. • Wherever possible, infiltration systems should not be installed within ±50 feet ofthe tops of slopes steeper than 15 percent or within H/3 from the tops of slopes (where H equals the height of slope). Wherever possible, infiltrations systems should not be placed within a distance of H/2 from the toes of slopes (where H equals the height of slope). Miles-Pacific, LLC W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 43 The landscape architect should be notified ofthe location ofthe proposed OIRRS. If landscaping is proposed within the OIRRS, consideration should be given to the type of vegetation chosen and their potential effect upon subsurface improvements (i.e., some trees/shrubs will have an effect on subsurface improvements with their extensive root systems). Over-watering landscape areas above, or adjacent to, the proposed OIRRS could adversely affect performance ofthe system. Areas adjacent to, or within, the OIRRS that are subject to inundation should be properly protected against scouring, undermining, and erosion, in accordance with the recommendations of the design engineer. Seismic shaking may result in the formation of a seiche which could potential overtop the banks of an OIRRS and result in down-gradient flooding and scour. If subsurface infiltration galleries/chambers are proposed, the appropriate size, depth interval, and ultimate placement ofthe detention/infiltration system should be evaluated by the design engineer, and be of sufficient width/depth to achieve optimum performance, based on the infiltration rates provided. In addition, proper debris filter systems will need to be utilized for the infiltration galleries/chambers. Debris filter systems will need to be self cleaning and periodically and regularly maintained on a regular basis. Provisions for the regular and periodic maintenance of any debris filter system is recommended and this condition should be disclosed to all interested/affected parties. Infiltrations systems should not be installed within ±8 feet of building foundations utility trenches, and walls, or a 1:1 (horizontal to vertical [h:v]) slope (down and away) from the bottom elements of these improvements. Alternatively, deepened foundations and/or pile/pier supported improvements may be used. Infiltrations systems should not be installed adjacent to pavement and/or hardscape improvements. Alternatively, deepened/thickened edges and curbs and/or impermeable liners may be utilized in areas adjoining the OIRRS. As with any OIRRS, localized ponding and groundwater seepage should be anticipated. The potential for seepage and/or perched groundwater to occur after site development should be disclosed to all interested/affected parties. Installation of infiltrations systems should avoid expansive soils (Expansion Index [E.I.] >51) or soils with a relatively high plasticity index (P.I. > 20). Infiltration systems should not be installed where the vertical separation of the groundwater level is less than ±10 feet from the base ofthe system. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 44 Where permeable pavements are planned as part of the system, the site Traffic Index (T.l.) should be less than 25,000 Average Daily Traffic (ADT), as recommended in Allen, et al. (2011). Infiltration systems should be designed using a suitable factor of safety (FOS) to account for uncertainties in the known infiltration rates (as generally required bythe controlling authorities), and reduction in performance overtime. As with any OIRRS, proper care will need to provided. Best management practices should be followed at all times, especially during inclement weather. Provisions for the management of any siltation, debris within the OIRRS, and/or overgrown vegetation (including root systems) should be considered. An appropriate inspection schedule will need to adopted and provided to all interested/affected parties. Any designed system will require regular and periodic maintenance, which may include rehabilitation and/or complete replacement ofthe filter media (e.g., sand, gravel, filter fabrics, topsoils, mulch, etc.) or other components utilized in construction, so that the design life exceeds 15 years. Due to the potential for piping and adverse seepage conditions, a burrowing rodent control program should also be implemented onsite. All or portions of these systems may be considered attractive nuisances. Thus, consideration ofthe effects of, or potential for, vandalism should be addressed. Newly established vegetation/landscaping (including phreatophytes) may have root systems that will influence the performance of the OIRRS or nearby LID systems. The potential for surface flooding, in the case of system blockage, should be evaluated by the design engineer. Any proposed utility backfill materials (i.e., inlet/outlet piping and/or other subsurface utilities) located within or near the proposed area of the OIRRS may become saturated. This is due to the potential for piping, water migration, and/or seepage along the utility trench line backfill. If utility trenches cross and/or are proposed near the OIRRS, cut-off walls or other water barriers will need to be installed to mitigate the potential for piping and excess water entering the utility backfill materials. Planned or existing utilities may also be subject to piping of fines into open-graded gravel backfill layers unless separated from overlying or adjoining OIRRS by geotextiles and/or slurry backfill. The use of OIRRS above existing utilities that might degrade/corrode with the introduction of water/seepage should be avoided. Miles-Pacific, LLC W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad . October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 45 Plan Specific The plans by BHA, Inc. (2012) indicate the construction of stormwater retention basins near the westerly margin of the site (Lots 18 and 19) and near the top of the cut slope descending to Interstate 5. In consideration of the long-term stability of this slope and nearby planned improvements, GSI recommends the following in addition to the above: The sides and bottoms of these basins and trenches should be lined with an impermeable liner that does not allow for percolated water to weaken the cut slope's soil/rock composition nor result in seepage at the cut slope face. The foundations for the surrounding retaining walls should be below a 1:1 (h:v) projection from the bottom ofthe detention basins(s). Proper maintenance and care of the basins will need to provided. Best management maintenance practices should be followed at all times, especially during inclement weather. Should regular inspection and/or required maintenance not be performed, the potential for malfunctioning of the detention systems will increase. All inlets, outlets and piping from these temporary drainage features should be properly backfilled and installed per City standards. Consideration should be given to the sizing of the existing brow ditch on the cut slope descending to Interstate 5. PRELIMINARY OUTDOOR POOL/SPA DESIGN RECOMMENDATIONS The following preliminary recommendations are provided for consideration in pool/spa design and planning. Actual recommendations should be provided by a qualified geotechnical consultant, based on site specific geotechnical conditions, including supplemental 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 code, and geometry of the proposed improvements. Recommendations for pools/spas and/or deck flatwork underlain by expansive soils, or for areas with differential settlement greater than y4-inch over 40 feet horizontally, will be more onerous than the preliminary recommendations presented below. The conditions and recommendations presented herein should be disclosed to all homeowners and any interested/affected parties. General 1. The equivalent fluid pressure to be used for the pool/spa design should be 60 pounds per cubic foot (pcf) for pool/spa walls with level backfill, and 75 pcf for a 2:1 sloped backfill condition. In addition, backdrains should be provided behind pool/spa walls subjacent to slopes. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoilS, InC. October 31, 2012 File:wp12\6300\6324a.pge Page 46 2. Passive earth pressure may be computed as an equivalent fluid having a density of 150 pcf, to a maximum lateral earth pressure of 1,000 pounds per square foot (psf). 3. An allowable coefficient of friction between soil and concrete of 0.30 may be used with the dead load forces. 4. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 5. Where pools/spas are planned near structures, appropriate surcharge loads need to be incorporated into design and construction by the pool/spa designer. This includes, but is not limited to landscape berms, decorative walls, footings, built-in barbeques, utility poles, etc. 6. All pool/spa walls should be designed as "free standing" and be capable of supporting the water in the pool/spa without soil support. The shape of pool/spa in cross section and plan view may affect the performance of the pool, from a geotechnical standpoint. Pools and spas should also be designed in accordance with Section 1808.7.3 of the 2010 CBC (CBSC, 2010). Minimally, the bottoms ofthe 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. 7. The soil beneath the pool/spa bottom should be uniformly moist with the same stiffness throughout. If a fill/paralic deposits transition occurs beneath the pool/spa bottom, the paralic deposits should be overexcavated to a minimum depth of 48 inches, and replaced with compacted fill, such that there is a uniform blanket that is a minimum of 48 inches below the pool/spa shell. If very low expansive soil is used for fill, the fill should be placed at a minimum of 95 percent relative compaction, at optimum moisture conditions. This requirement should be 90 percent relative compaction at over optimum moisture if the pool/spa is constructed within or near expansive soils. The potential for grading and/or re-grading ofthe pool/spa bottom, and attendant potential for shoring and/or slot excavation, needs to be considered during all aspects of pool/spa planning, design, and construction. 8. Ifthe pool/spa is founded entirely in compacted fill placed during rough grading, the deepest portion ofthe 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, Miles-Pacific, LLC ~ W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoilS, Inc. October 31, 2012 Flle:wp12\6300\6324a.pge Page 47 and be fitted with slip or expandible joints between connections transecting varying soil conditions. 11. An elastic expansion joint (flexible waterproof sealant) should be installed to prevent water from seeping into the soil at all deck joints. 12. A reinforced grade beam should be placed around skimmer inlets to provide support and mitigate cracking around the skimmer face. 13. In order to reduce unsightly cracking, deck slabs should minimally be 4 inches thick, and reinforced with No. 3 reinforcing bars at 18 inches on-center. All slab reinforcement should be supported to ensure proper mid-slab positioning during the placement of concrete. Wire mesh reinforcing is specifically not recommended. Deck slabs should not be tied to the pool/spa structure. Pre-moistening and/or pre-soaking of the slab subgrade is recommended, to a depth of 12 inches (optimum moisture content), or 18 inches (120 percent of the soil's optimum moisture content, or 3 percent over optimum moisture content, whichever is greater), for very low to low, and medium expansive soils, respectively. This moisture content should be maintained in the subgrade soils during concrete placement to promote uniform curing of the concrete and minimize the development of unsightly shrinkage cracks. Slab underlayment should consist of a 1- to 2-inch leveling course of sand (S.E.>30) and a minimum of 4 to 6 inches of Class 2 base compacted to 90 percent. Deck slabs within the H/3 zone, where H is the height of the slope (in feet), will have an increased potential for distress relative to other areas outside of the H/3 zone. If distress is undesirable, improvements, deck slabs or flatwork should not be constructed closer than H/3 or 7 feet (whichever is greater) from the slope face, in order to reduce, but not eliminate, this potential. 14. Pool/spa bottom or deck slabs should be founded entirely on competent paralic deposits or properly compacted fill. Fill should be compacted to achieve a minimum 90 percent relative compaction, as discussed above. Prior to pouring concrete, subgrade soils below the pool/spa decking should be throughly watered to achieve a moisture content that is at least 2 percent above optimum moisture content, to a depth of at least 18 inches below the bottom of slabs. This moisture content should be maintained in the subgrade soils during concrete placement to promote uniform curing ofthe concrete and minimize the development of unsightly shrinkage cracks. 15. In order to reduce unsightly cracking, the outer edges of pool/spa decking to be bordered by landscaping, and the edges immediately adjacent to the pool/spa, should be underlain by an 8-inch wide concrete cutoff shoulder (thickened edge) extending to a depth ofat least 12 inches belowthe bottoms ofthe 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. Miles-Pacific, LLC W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoils, InC. October 31, 2012 File:wp12\6300\6324a.pge Page 48 Deck slabs may be minimally reinforced with No. 3 reinforcing bars placed at 18 inches on-center, in both directions. All slab reinforcement should be supported on chairs to ensure proper mid-slab positioning during the placement of concrete. 16. Surface and shrinkage cracking of the finish slab may be reduced if a low slump and water-cement ratio are maintained during concrete placement. Concrete utilized should have a minimum compressive strength of 4,000 psi and a maximum water to cement ratio of 0.50. Excessive water added to concrete prior to placement is likely to cause shrinkage cracking, and should be avoided. Some concrete shrinkage cracking, however, is unavoidable. 17. Joint and sawcut locations for the pool/spa deck should be determined by the design engineer and/or contractor. However, spacings should not exceed 6 feet on-center. 18. Considering the nature of the onsite earth materials, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls/backcuts at the angle of repose (typically 25 to 45 degrees), should be anticipated. AH excavations should be observed 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, state, and local safety codes. Should adverse conditions exist, appropriate recommendations should be offered atthattime bythe geotechnical consultant. GSI does not consult in the area of safety engineering and the safety of the construction crew is the responsibility of the pool/spa builder. 19. It is imperative that adequate provisions for surface drainage are incorporated by the homeowners into their overall improvement scheme. Ponding water, ground saturation and flow over slope faces, are all situations which must be avoided to enhance long term performance ofthe pool/spa and associated improvements, and reduce the likelihood of distress. 20. Regardless ofthe 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 bythe geotechnical consultant and the pool/spa builder. 21. For pools/spas built within (all or part) ofthe 2010 CBC setback and/or geotechnical setback, as indicated in the site geotechnical documents, special foundations are recommended to mitigate the affects of creep, lateral fill extension, expansive soils and settlement on the proposed pool/spa. Most municipalities or County reviewers do not consider these effects in pool/spa plan approvals. As such, where pools/spas are proposed on 20 feet or more of fill, medium or highly expansive soils, or rock fill with limited "cap soils" and built within 2010 CBC setbacks, or Miles-Pacific, LLC ~ W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 49 within the influence of the creep zone, or lateral fill extension, the following should be considered during design and construction: OPTION A: Shallow foundations with or without overexcavation of the pool/spa "shell," such that the pool/spa is surrounded by 5 feet of very low to low expansive soils (without irreducible particles greater that 6 inches), and the pool/spa walls closer to the slope(s) are designed to be free standing. GSI recommends a pool/spa under-drain or blanket system (see Typical Pool/Spa Detail [Appendix E]). 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 ofthe pool/spa is likely over the life ofthe 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 theslope(s) are designed to be free standing. The need for a pool/spa under-drain system may be installed for leak detection purposes. Piers that support the pool/spa should be a minimum of 12 inches in diameter and at a spacing to provide vertical and lateral support of the pool/spa, in accordance with the pool/spa designers recommendations, local code, and the 2010 CBC. The pool/spa builder and owner in this second scenario construction technique should be more satisfied with pool/spa performance. This construction will reduce settlement and creep effects on the pool/spa; however, it will not eliminate these potentials, nor make the pool/spa "leak-free." 22. The temperature of the water lines for spas and pools may affect the corrosion properties of site soils, thus, a corrosion specialist should be retained to review all spa and pool plans, and provide mitigative recommendations, as warranted. Concrete mix design should be reviewed by a qualified corrosion consultant and materials engineer. 23. All pool/spa utility trenches should be compacted to 90 percent of the laboratory standard, under the full-time observation and testing of a qualified geotechnical consultant. Utility trench bottoms should be sloped away from the primary structure on the property (typically the residence). 24. Pool and spa utility lines should not cross the primary structure's utility lines (i.e., not stacked, or sharing of trenches, etc.). 25. The pool/spa or associated utilities should not intercept, interrupt, or otherwise adversely impact any area drain, roof drain, or other drainage conveyances. If it is necessary to modify, move, or disrupt existing area drains, subdrains, or tightiines, Miles-Pacific, LLC W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 50 then the design civil engineer should be consulted, and mitigative measures provided. Such measures should be further reviewed and approved by the geotechnical consultant, priorto proceeding with any further construction. 26. The geotechnical consultant should review and approve all aspects of pool/spa and flatwork design prior to construction. A design civil engineer should review all aspects of such design, including drainage and setback conditions. Prior to acceptance of the pool/spa construction, the project builder, geotechnical consultant and civil designer should evaluate the performance ofthe area drains and other site drainage pipes, following pool/spa construction. 27. All aspects of construction should be reviewed and approved by the geotechnical consultant, including during excavation, 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 bythe geotechnical and design civil engineer priorto construction. Field adjustments should not be allowed until written approval of the proposed field changes are obtained from the geotechnical and design civil engineer. 29. Disclosure should be made to homeowners and builders, contractors, and any interested/affected parties, that pools/spas built within about 15 feet of the top of a slope, and/or H/3, where H is the height ofthe slope (in feet), will experience some movement or tilting. While the pool/spa shell or coping may not necessarily crack, the levelness of the pool/spa will likely tilt toward the slope, and may not be esthetically pleasing. The same is true with decking, flatwork and other improvements in this zone. 30. Failure to adhere to the above recommendations will significantly increase the potential for distress to the pool/spa, flatwork, etc. 31. Local seismicity and/or the design earthquake will cause some distress to the pool/spa and decking or flatwork, possibly including total functional and economic loss. 32. The information and recommendations discussed above should be provided to any contractors and/or subcontractors, or homeowners, interested/affected parties, etc., that may perform or may be affected by such work. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad ^ October 31,2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 51 DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specitications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post-construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occurthroughoutthe life of the slope, and is anticipated to potentially affect improvements or structures (e.g., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the till'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 2010 CBC), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. Expansion joints in walls should be placed no greaterthan 20feet on-center, and in accordance with the structural engineer's recommendations. All ofthese measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to all 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 overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-watering should be avoided as it adversely affects site improvements, and causes perched groundwater conditions. Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of sun/iving 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 Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad . October 31,2012 File:wp12\6300\6324a.pge GeoSollS, InC. Page 52 recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to all interested/affected parties. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes. Surface drainage should be sufficient to mitigate ponding of water anywhere on the property, and especially near structures and tops of slopes. Surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within the property 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 tops of slopes, and not allowed to pond and/or seep into the ground. In general, site drainage should conform to Section 1804.3 of the 2010 CBC. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Building pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Erosion Control Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum distance of 10 feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete Miles-Pacific, LLC W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad _ October 31, 2012 File:wp12\6300\6324a.pge GeoSoilS, InC. Page 53 flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrierto 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, ff the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or other non-erosive devices (e.g., paved swales or ditches; below grade, solid tight-lined PVC pipes; etc.), that will carry the water away from the house, to an appropriate outiet, in accordance with the recommendations of the design civil engineer. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into tinal design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Site Improvements If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. Pools and/or spas should not be constructed without specific design and construction recommendations from GSI, and this construction recommendation should be provided to all 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. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoilS, InC. October 31, 2012 File:wp12\6300\6324a.pge Page 54 Tile Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street, driveway approaches, driveways, parking areas, and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this tirm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose ofthe 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. All excavations should be observed by an engineering geologist or soil engineer from GSI, prior to workers entering the excavation or trench, and minimally conform to CAL-OSHA, state, and local safety codes. Should adverse conditions exist, appropriate recommendations would be offered atthattime. The above recommendations should be provided to any contractors and/or subcontractors, or homeowners, etc., that may perform such work. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoilS, Inc. October 31, 2012 File:wp12\6300\6324a.pge Page 55 utilitv Trench Backfill 1. All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent ofthe laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to evaluate the desired results. 2. Exterior trenches adjacent to, and within areas extending below a 1:1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to evaluate the desired results. 3. All trench excavations should conform to CAL-OSHA, state, and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations ofthe structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: • During grading/recertification. • During excavation. • During placement of subdrains or other subdrainage devices, prior to placing fill and/or backfill. After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor retarders (i.e., visqueen, etc.). Miles-Pacific, LLC W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoilS, InC. October 31, 2012 File:wp12\6300\6324a.pge Page 56 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 construction/repair. When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construction. A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer/designer. Please note that the recommendations contained herein are not intended to preclude the transmission of water or vapor through the slab or foundation. The stiuctural engineer/foundation and/or slab designer should provide recommendations to not allow water or vapor to enter into the structure so as to cause damage to another building component, or so as to limit the installation of the type of flooring materials typically used forthe particular application. The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and deflections in the various slab, foundation, and other elements in order to develop appropriate, design-specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer/designer should consider all applicable codes and authoritative sources where needed. If analyses bythe structural engineer/designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely that some, more restrictive details will be required. Ifthe structural engineer/designer has any questions or requires further assistance, they should not hesitate to call or othen^/ise transmit their requests to GSI. In order to mitigate Miles-Pacific, LLC ~ W.O. 6324-A-SC 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoilS, InC. October 31, 2012 File:wp12\6300\6324a.pge Page 57 potential distress, the foundation and/or improvement's designer should confirm to GSI and the governing agency, in writing, thatthe proposed foundations and/or improvements can tolerate the amount of differential settlement and/or expansion characteristics and other design criteria specified herein. PLAN REVIEW Final project plans (grading, precise grading, foundation, retaining wall, landscaping, etc.), should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. Improvement plans should also be reviewed for subdrainage and piping (washing of fines) conditions, in light ofthe proposed sewer's close proximity to the cut slope descending to Interstate 5. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative ofthe 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. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notiA/ithstanding 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 servicesforthis portion ofthe project. All samples will be disposed of after 30 days, unless specifically requested by the client, in writing. Miles-Pacific, LLC W.O. 6324-A-SG 2373 & 2375 Pio Pico Drive, Garlsbad GeoSoilS, Inc. October 31, 2012 File:wp12\6300\6324a.pge Page 58 APPENDIXA REFERENCES GeoSoils, Inc. APPENDIX A REFERENCES ACI Committee 318,2008, Building code requirements for structural concrete (ACI318-08) and commentary, dated January. ACI Committee 302,2004, Guide for concrete floor and slab construction, ACI 302.1 R-04, dated June. Allen, v., Connerton, A., and Carlson, C, 2011, Introduction to Infiltration Best Management Practices (BMP), Contech Construction Products, Inc., Professional Development Series, dated December. American Society for Testing and Materials (ASTM), 2003, Standard test method for infiltration rate of soils in field using double-ring infiltrometer, Designation D 3385-03, dated August. , 1998, Standard practice for installation of water vapor retarder used in contact with earth or granular fill under concrete slabs. Designation: E 1643-98 (Reapproved 2005). , 1997, Standard specification for plastic water vapor retarders used in contact with soil or granular fill under concrete slabs, Designation: E 1745-97 (Reapproved 2004). American Society of Civil Engineers, 2006, Minimum design loads for buildings and other structures, ASCE Standard ASCE/SEI 7-05. BHA, Inc., 2012, Tentative map and coastal development plan CT 12-01/CDP 12-15 for: Miles-Pacific Subdivision, Carlsbad, CA, Sheetsi, 2, and 3 of 5,30-scale, plot dated August 29. Blake, Thomas F., 2000a, EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version. , 2000b, EQSEARCH, A computer program for the estimation of peak horizontal acceleration from California historical earthquake catalogs; Updated to December 2009, Windows 95/98 version. Bozorgnia, Y., Campbell K.W., and Niazi, M., 1999, Vertical ground motion: Characteristics, relationship with horizontal component, and building-code implications; Proceedings of the SMIP99 seminar on utilization of strong-motion data, September 15, Oakland, pp. 23-49. GeoSoils, Inc. Bryant, W.A., and Hart, E.W., 2007, Fault-rupture hazard zones in California, Alquist-Priolo earthquake fault zoning act with index to earthquake fault zones maps; California Geological Survey, Special Publication 42, interim revision. California Building Standards Commission, 2010, California building code. California Department of Water Resources, 1993, Division of Safety of Dams, Guidelines for the design and construction of small embankments dams, reprinted January. California Stormwater Quality Association (CASQA), 2003, Stormwater best management practice handbook, new development and redevelopment, dated January. County of San Diego, Department of Planning and Land Use, 2007, Low impact development (LID) handbook, stormwater management strategies, dated December 31. GeoSoils, Inc., 2008, Update preliminary geotechnical evaluation, APNs 155-140-37, and -38, Jefferson Street, City of Carlsbad, San Diego County, California, W.O. 5701-A-SC, dated June 17. , 2003, Preliminary geotechnical evaluation, APNs 155-140-37, and -38, Jefferson Street, City of Carlsbad, San Diego County, California, W.O. 3213-A-SC, dated September 18. Hydrologic Solutions, StormChamber™ installation brochure, pgs. 1 through 8, undated. International Conference of Building Officials, 2001, California building code, California code of regulations titie 24, part 2, volume 1 and 2. , 1998, Maps of known active fault near-source zones in California and adjacent portions of Nevada. Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, Map Sheet No. 6, scale 1:750,000. Kanare, H.M., 2005, Concrete floors and moisture, Engineering Bulletin 119, Portland Cement Association. Kennedy, M.P, and Tan, S.S, 2005, Geologic map ofthe Oceanside 30' x 60' quadrangle, California, United States Geological Sun/ey. Romanoff, M., 1957, Underground corrosion, originally issued April 1. Miles-Pacific, LLC _ Appendix A File:e:\wp12\6300\6309a.pge GeoSoilS, InC. Page 2 Seed, 2005, Evaluation and mitigation of soil liquefaction hazard "evaluation of field data and procedures for evaluating the risk of triggering (or inception) of liquefaction", in Geotechnical earthquake engineering; short course, San Diego, California, April 8-9. Sowers and Sowers, 1979, Unified soil classification system (After U. S. WatenA/ays Experiment Station and ASTM 02487-667) in Introductory Soil Mechanics, New York. State of California, 2011, Civil Code, Sections 895 et seq. State of California Department of Transportation, Division of Engineering Services, Materials Engineering, and Testing Services, Corrosion Technology Branch, 2003, Corrosion Guidelines, Version 1.0, dated September. Tan, S.S., and Giffen, D.G., 1995, Landslide hazards inthe northern partof the San Diego Metropolitan area, San Diego County, California, Landslide hazard identification map no. 35, Plate 35A, Departmentof Conservation, Division of Mines and Geology, DMG Open File Report 95-04. Tan, S.S., and Kennedy, M.P., 1996, Geologic maps ofthe northwestern partof San Diego County, California: California Division of Mines and Geology, Open File Report 96-02. United States Geological Survey, 2011, Seismic hazard curves and uniform hazard response spectra - v5.1.0, dated February 2 , 1999, San Luis Rey quadrangle, San Diego County, California, 7.5 minute series, 1:24,000 scale. Miles-Pacific, LLC . Appendix A File:e:\wp12\6300\6309a.pge GeoSoilS, InC. Page 3 APPENDIX B TEST EXCAVATION LOGS GeoSoils, Inc. UNIFIED SOIL CLASSIFICATION SYSTEM CONSISTENCY OR RELATIVE DENSITY Major Divisions Group Symbols Typical Names CRITERIA > 0) w o o CM o z CO ^ X! O •S "> O iS OJ P o lO c x: J2 (U I o c sis OD § « <D Z CO i= m (o £ g S P 8 !S GW Well-graded gravels and gravel- sand nnixtures, little or no fines standard Penetration Test GP Poorly graded gravels and gravel-sand mixtures, little or no fines GM Silty gravels gravel-sand-siit mixtures GC Clayey gravels, gravel-sand-clay mixtures SW O CO Well-graded sands and gravelly sands, little or no fines Penetration Resistance N (blows/ft) Relative Density 0-4 Very loose 4-10 Loose 10-30 Medium 30-50 Dense > 50 Very dense SP Poorly graded sands and gravelly sands, little or no fines SM Silty sands, sand-silt mixtures sc Clayey sands, sand-clay mixtures ML Inorganic silts, very fine sands, rock flour, silty or clayey fine sands standard Penetration Test o o CO ^ T3 (Q CD O. O E_ •g :2 o •= m CO <D CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays OL Organic silts and organic silty clays of low plasticity o E o m JO m •g -g 5 MH Inorganic silts, micaceous or diatomaceous fine sands or silts, elastic silts CH Inorganic clays of high plasticity, fat clays OH Organic clays of medium to high plasticity Penetration Resistance N (blows/ft) Consistency Unconfined Compressive strength (tons/fP) <2 Very Soft <0.25 2-4 Soft 0.25 - .050 4-8 Medium 0.50-1.00 8-15 Stiff 1.00 - 2.00 15-30 Very Stiff 2.00 - 4.00 >30 Hard >4.00 Highly Organic Soils PT Peat, mucic, and other highly organic soils 3/4" #4 #10 #40 #200 U.S. Standard Sieve Unified Soil Cobbles Gravel Sand Silt or Clay Classification Cobbles coarse fine coarse medium fine Silt or Clay MOISTURE CONDITIONS Dry Absence of moisture: dusty, dry to the touch Slightly Moist Below optimum moisture content for compaction Moist Near optimum moisture content Very Moist Above optimum moisture content Wet Visible free water; below water table MATERIAL QUANTITY trace 0 - 5 % few 5-10% little 10-25% some 25 - 45 % OTHER SYMBOLS C Core Sample S SPT Sample B Bulk Sample • Groundwater Qp Pocket Penetrometer BASIC LOG FORMAT: Group name. Group symbol, (grain size), color, moisture, consistency or relative density. Additional comments: odor, presence of roots, mica, gypsum, coarse grained particles, etc. EXAMPLE: Sand (SP), fine to medium grained, brown, moist, loose, trace sill, little fine gravel, few cobbles up to 4" in size, some hair roots and rootlets. File:Mgr: c;\SoilClassif.wpd PLATE B-1 w.o. 6324-A-SC Miles-Pacific, LLC Carlsbad Logged By: RB September 20, 2012 LOG OF EXPLORATORY TEST PITS TEST PIT NO. ELEV. (ft.) DEPTH (ft.) GROUP SYMBOL SAMPLE DEPTH (ft.) MOISTURE (%) FIELD DRY DENSITY (pcf) DESCRIPTION TP-1 ±1011/2 0-1 SM QUATERNARY COLLUVIUM: SILTY SAND with minor CLAY, brown, drv becoming moist with depth, dense at the surface becoming medium dense with depth. TP-1 ±1011/2 1-21/2 SM WEATHERED YOUNGER PARALIC DEPOSITS: SILTY SAND, dark yellowish brown, moist, medium dense; porous (pore space up to ~y4 inch diameter), trace iron-stone concretions. TP-1 ±1011/2 21/2-3% SC UND @3 Buik @ 3-31/2 11.2 119.1 QUATERNARY PALEOSOL: CLAYEY SAND, dark vellowish red. moist, medium dense; slightly porous, manganese oxide staining, weak prismatic structure. TP-1 ±1011/2 33/4-4 SM QUATERNARY OLDER PARALIC DEPOSITS: SILTY SAND, dark vellowish brown and reddish yellow, moist, dense, thickly bedded. TP-1 UND = Undisturbed Total Depth = 4' No Groundwater/Caving Encountered Backfilled 9/20/2012 TP-2 ±99 0-1 SM QUATERNARY COLLUVIUM: SILTY SAND, dark brown, drv becomina moist with depth, dense becoming medium dense with depth. TP-2 ±99 1-3 SM HIGHLY WEATHERED YOUNGER PARALIC DEPOSITS: SILTY SAND, dark TP-2 ±99 1-3 SM yellowish brown, moist, medium dense; trace iron-stone concretions. TP-2 ±99 3-4 SC UND @ 3% 10.2 124.6 QUATERNARY OLDER PARALIC DEPOSITS: CLAYEY SAND, arav and reddish yellow, moist, dense. TP-2 Total Depth = 4' No Groundwater/Caving Encountered Backfilled 9/20/2012 PLATE B-2 w.o. 6324-A-SC Miles-Pacific, LLC Carlsbad Logged By: RB September 20, 2012 LOG OF EXPLORATORY TEST PITS TEST PIT NO. ELEV. (ft.) DEPTH (ft.) GROUP SYMBOL SAMPLE DEPTH (ft.) MOISTURE (%) FIELD DRY DENSITY (pcf) DESCRIPTION TP-3 ±83 0-1/6 GP GRAVEL: 3/4 inch, anaular. TP-3 ±83 1/6-3/4 SP QUATERNARY ALLUVIUM: SAND, arav to vellowish brown, dry. medium dense. TP-3 ±83 3/4-2 SM QUATERNARY COLLUVIUM: SILTY SAND, dark brown, moist, medium dense. TP-3 ±83 2-5 SM UND@4 8.8 110.2 WEATHERED QUATERNARY YOUNGER PARALIC DEPOSITS: SILTY TP-3 ±83 2-5 SM UND@4 8.8 110.2 SAND, dark yellowish brown, moist, medium dense; trace iron-stone concretions. TP-3 ±83 5-7 SP/GP QUATERNARY YOUNGER PARALIC DEPOSITS: fine arained SAND with COBBLE/SANDY COBBLES, dark yellowish brown, moist, dense. TP-3 Total Depth = 7' No Groundwater/Caving Encountered Backfilled 9/20/2012 TP-4 ±81 0-1 SM QUATERNARY COLLUVIUM: SILTY SAND, dark brown, dry. medium dense. TP-4 ±81 1-61/2 SM WEATHERED YOUNGER PARALIC DEPOSITS: SILTY SAND, dark yellowish brown, moist, medium dense; trace iron-stone concretions. TP-4 ±81 61/2-8 SP UND @ 53/4 7.7 108.1 QUATERNARY YOUNGER PARALIC DEPOSITS: fine arained SAND reddish yellow and dark yellowish brown, moist, dense; cobble encountered @8'. TP-4 Practical Refusal due to Cobble @ 8' No Groundwater/Caving Encountered Backfilled 9/20/2012 PLATE B-3 w.o. 6324-A-SC Miles-Pacific, LLC Carlsbad Logged By: RB September 20, 2012 LOG OF EXPLORATORY TEST PITS TEST PIT NO. ELEV. (ft.) DEPTH (ft.) GROUP SYMBOL SAMPLE DEPTH (ft.) MOISTURE (%) FIELD DRY DENSITY (pcf) DESCRIPTION HA-1 ±85 0-1 1/2 SP QUATERNARY COLLUVIUM: vervfinenraineri SAND with Sll T riark hrnwn moist, loose. HA-1 ±85 1 1/2-4 SP/SM WEATHERED YOUNGER PARALIC DEPOSITS: verv fine nraineri .SAND with SILT to SILTY SAND, dark yellowish brown, moist, medium dense. HA-1 ±85 4-6 SM/SP QUATERNARY OLDER PARALIC DEPOSITS: SILTY SAND tn very fin^ grained SAND with SILT, reddish yellow to dark yellowish brown, moist becoming wet with depth, dense. HA-1 Total Depth =6' No Groundwater/Caving Encountered Backfilled 9/20/2012 HA-2 ±103 0-1 1/2 QUATERNARY COLLUVIUM: SILTY SAND dark hrnwn damp humming moist with depth, medium dense becoming loose with depth. HA-2 ±103 1 1/2-3 WEATHERED YOUNGER PARALIC DEPOSITS: SILTY SAND dark yellowish brown, moist, medium dense; trace iron-stone concretions. HA-2 ±103 3-4 CLAYEY SAND, dark yellowish brown, wet, medium dense becoming dense with depth; trace iron-stone concretions. HA-2 ±103 4-43/4 QUATERNARY OLDER PARALIC DEPOSITS: Cl AYFY .SANH rpririish yellow and dark yellowish brown, wet, dense. HA-2 Total Depth = 43/4' No Groundwater/Caving Encountered Backfilled 9/20/2012 PLATE B-4 W.o. 6324-A-SC Miles-Pacific, LLC Carlsbad Logged By: RB September 20, 2012 LOG OF EXPLORATORY TEST PITS TEST PIT NO. ELEV. (ft.) DEPTH (ft.) GROUP SYMBOL SAMPLE DEPTH (ft.) MOISTURE (%) FIELD DRY DENSITY (pcf) DESCRiPTION HA-3 ±98 0-1 1/2 SM QUATERNARY COLLUVIUM: SILTY SAND, dark brown, drv. medium dense. HA-3 ±98 1 1/2-2 SM WEATHERED YOUNGER PARALIC DEPOSITS: SILTY SAND, dark yellowish brown, dry becoming damp with depth, medium dense. HA-3 ±98 2-21/2 SM QUATERNARY OLDER PARALIC DEPOSITS: SILTY SAND, dark vellowish brown, damp, very dense. HA-3 Practical Refusal @ 2V2 No Groundwater/Caving Encountered Backfilled 9/20/2012 HA-4 ±91 0-3/4 QUATERNARY COLLUVIUM: verv fine arained SAND with SILT, dark brown, wet, loose. HA-4 ±91 3/4-1 1/4 WEATHERED YOUNGER PARALIC DEPOSITS: SILTY SAND, dark yellowish brown, wet, loose becoming medium dense with depth. HA-4 ±91 1 1/4-2 QUATERNARY YOUNGER PARALIC DEPOSITS: SANDY CLAY, dark yellowish brown and gray, wet, stiff. HA-4 ±91 2-21/2 QUATERNARY OLDER PARALIC DEPOSITS: SANDY CL^Y reddish vellow and dark yellowish brown, wet, very stiff. HA-4 ±91 21/2-51/2 CLAYEY SAND, reddish yellow and dark yellowish brown, wet, dense; becoming SILTY SAND @ 4' HA-4 Total Depth = 51/2' No Groundwater/Caving Encountered Backfilled 9/20/2012 PLATE B-5 APPENDIXC EQFAULT, EQSEARCH, AND PHGA GeoSoils, Inc. EQFAULT Version 3.00 DETERMINISTIC ESTIMATION OF PEAK ACCELERATION FROM DIGITIZED FAULTS JOB NUMBER: 6324-A-SC DATE: 09-24-2012 JOB NAME: MILES-PACIFIC, LLC CALCULATION NAME: 6324 FAULT-DATA-FILE NAME: C:\Program Files\EQFAULTl\CGSFLTE.DAT SITE COORDINATES: SITE LATTTUDE: 33.1721 SITE LONGITUDE: 117.3457 SEARCH RADIUS: 62.14 mi ATTENUATION RELATION: 11) Bozorgnia Campbell Niazi (1999) Hor.-Pleist Soil-Cor UNCERTAINTY (M^Median, S=sigma): s Number of siqmas: 1.0 DISTANCE MEASURE: cdist SCOND: 1 Basement Depth: .00 km Campbell SSR: 0 Campbell SHR- 0 COMPUTE PEAK HORIZONTAL ACCELERATION FAULT-DATA FILE USED: C:\Program Files\EQFAULTl\CGSFLTE.DAT MINIMUM DEPTH VALUE (km): 3.0 Page 1 W.O. 6324-A-SC Plate C-1 EQFAULT SUMMARY DETERMINISTIC SITE PARAMETERS Page 1 ESTIMATED MAX. EARTHQUAKE EVENT APPROXIMATE ABBREVIATED DISTANCE MAXIMUM PEAK EST. SITE FAULT NAME mi (km) EARTHQUAKE SITE INTENSITY MAG.(Mw) ACCEL, g MOD.MERC. NEWPORT-INGLEWOOD (Offshore) 5.3( 8.5) 7.1 0.597 x ROSE CANYON 6.0( 9.6) 7.2 0.580 x CORONADO BANK 21.6( 34.8) 7.6 0.267 IX ELSINORE (TEMECULA) 23.6( 38.0) 6.8 0.143 VIII ELSINORE (JULIAN) 24.0( 38.6) 7.1 0.172 VIII ELSINORE (GLEN IVY) 32.6( 52.4) 6.8 0.103 VII SAN JOAQUIN HILLS 34.3( 55.2) .6.6 0.121 VII PALOS VERDES 35.2( 56.7) 7.3 0.134 VIII EARTHQUAKE VALLEY 44.2( 71.2) 6.5 0.061 VI NEWPORT-INGLEWOOD (L.A.Basin) 45.0( 72.4) 7.1 0.090 VII SAN JACINTO-ANZA 46.1( 74.2) 7.2 0.094 VII SAN JACINTO-SAN JACINTO VALLEY • 46.5( 74.8) 6.9 0.076 VII CHINO-CENTRAL AVE. (Elsinore) 46.6( 75.0) 6.7 0.093 VII WHi11iER 50.5( 81.2) 6.8 0.065 VI SAN JACINTO-COYOTE CREEK 52.3( 84.2) 6.6 0.055 VI SAN JACINTO-SAN BERNARDINO 58.7( 94.5) 6.7 0.052 VI ELSINORE (COYOTE MOUNTAIN) 58.7( 94.5) 6.8 0.055 VI PUENTE HILLS BLIND THRUST 60.3( 97.1) 7.1 0.094 VII -END OF SEARCH-18 FAULTS FOUND WITHIN THE SPECIFIED SEARCH RADIUS. THE NEWPORT-INGLEWOOD (Offshore) FAULT IS CLOSEST TO THE SITE. IT IS ABOUT 5.3 MILES (8.5 km) AWAY. LARGEST MAXIMUM-EARTHQUAKE SITE ACCELERATION: 0.5971 g Page 2 W.O. 6324-A-SC Plate C-2 CALIFORNIA FAULT MAP MILES-PACIFIC, LLC 1100 1000 - 900 - 800 700 600 500 - 400 -- 300 200 - 100 -100 -400 -300 -200 -100 0 100 200 300 400 500 600 W.O. 6324-A-SC Plate C-3 MAXIMUM EARTHQUAKES MILES-PACIFIC, LLC 3 c o +3 (0 x. JS a> u u < .01 .001 A 1 10 Distance (mi) 100 W.O. 6324-A-SC Plate C-4 EQSEARCH Version 3.00 ESTIMATION OF PEAK ACCELERATION FROM CALIFORNIA EARTHQUAKE CATALOGS JOB NUMBER: 6324-A-SC DATE: 10-10-2012 JOB NAME: MILES-PACIFIC, LLC EARTHQUAKE-CATALOG-FILE NAME: ALLQUAKE.DAT SITE COORDINATES: SITE LATITUDE: 33.1721 SITE LONGITUDE: 117.3457 SEARCH DATES: START DATE: 1800 END DATE: 2011 SEARCH RADIUS: 62.1 mi 100.0 km ATTENUATION RELATION: 11) Bozorgnia Campbell Niazi (1999) Hor.-Pleist. Soil-Cor. UNCERTAINTY (M=Median, S=Sigma): S Number of Sigmas: 1.0 ASSUMED SOURCE TYPE: SS [SS=Strike-slip, DS=Reverse-slip, BT=Blind-thrust] SCOND: 1 Depth Source: A Basement Depth: .00 km Campbell SSR: 0 Campbell SHR: 0 COMPUTE PEAK HORIZONTAL ACCELERATION MINIMUM DEPTH VALUE (km): 3.0 Page 1 W.O. 6324-A-SC Plate C-5 EARTHQUAKE SEARCH RESULTS Page 1 FILE LAT. LONG. CODE NORTH WEST DMG 33 .0000 117 .3000 MGI 33 .0000 117 .0000 MGI 32 .8000 117 .1000 PAS 32 .9710 117 .8700 DMG 32 .7000 117 .2000 T-A 32 .6700 117 .1700 T-A 32 .6700 117 .1700 T-A 32 .6700 117 .1700 DMG 33 .7000 117 .4000 DMG 33 .7000 117 .4000 DMG 33 .7000 117 .4000 DMG 33 .2000 116 .7000 DMG 33 .6990 117 .5110 DMG 32 .8000 116 .8000 MGI 33 .2000 116 .6000 DMG 33 .7100 116 .9250 DMG 33 .7500 117 .0000 DMG 33 .7500 117 .0000 MGI 33 .8000 117 .6000 DMG 33 .5750 117 .9830 DMG 33 .6170 117 .9670 DMG 33 .8000 117 .0000 DMG 33 6170 118 0170 DMG 33 9000 117 2000 GSP 33 5290 116 5720 GSG 33 4200 116 4890 PAS 33 5010 116 5130 GSP 33 5080 116. 5140 DMG 33 6830 118. 0500 DMG 33 5000 116. 5000 DMG 33. OOOO 116. 4330 DMG 33. 7000 118. 0670 DMG 33. 7000 118. 0670 DMG 34. OOOO 117. 2500 MGI 34. OOOO 117. 5000 DMG 33. 7500 118. 0830 DMG 33. 7500 118. 0830 DMG 33. 7500 118. 0830 DMG 33. 7500 118. 0830 DMG 33. 7500 118. 0830 DMG 133. 3430 116. 3460 GSG 1 33. 9530 117. 76101 DMG 1 33. 9500 116.8500! DMG 133. 7830 118. 13301 DATE TIME (UTC) H M Sec 1 SITE SITE DEPTH QUAKE 1 ACC. MM (km) MAG, 1 g INT. 0.0 6.50 0.227 IX 0.0 5.00 0.047 VI 0.0 5.00 0.037 V 6.0 5.30 0.039 V 0.0 5.90 0.055 VI 0.0 5.00 0.030 V 0.0 5.00 0.030 V 0.0 5.00 0.030 V 0.0 6.00 0.054 VI 0.0 5.00 0.030 V 0.0 5.00 0.030 V 0.0 5.00 0.029 V 10.0 5.50 0.038 V 0.0 5.70 0.040 V 0.0 5.30 0.030 V 16.5 5.00 0.024 V 0.0 6.80 0.074 VII 0.0 5.00 0.024 V 0.0 5.00 0.023 IV 0.0 5.20 0.026 V 0.0 6.30 0.050 VI 0.0 6.40 0.053 VI 0.0 5.10 0.023 IV 0.0 6.00 0.038 V 14.0 5.20 0.023 IV 14.0 5.50 0.027 V 13.6 5.50 0.027 V 15.0 5.10 0.021 IV 0.0 5.50 0.026 V 0.0 5.00 0.020 IV 0.0 5.10 0.021 IV 0.0 5.10 0.020 IV 0.0 5.10 0.020 IV 0.0 6.25 0.039 V 0.0 7.00 0.065 VI 0.0 5.10 0.019 1 IV 0.0 5.00 0.018 1 IV 0.0 5.10 0.019 1 IV 0.0 5.00 0.018 1 IV 0.0 5.30 0.022 1 IV 20.0 5.801 0.029 1 V 14.0 5.301 0.021 1 IV 0.0 5.001 0.017 1 IV 0.0 5.401 0.021 1 IV APPROX. DISTANCE mi [km] 11/22/1800 09/21/1856 05/25/1803 07/13/1986 05/27/1862 12/00/1856 10/21/1862 05/24/1865 05/15/1910 04/11/1910 05/13/1910 01/01/1920 05/31/1938 10/23/1894 10/12/1920 09/23/1963 04/21/1918 06/06/1918 04/22/1918 03/11/1933 03/11/1933 12/25/1899 03/14/1933 12/19/1880 06/12/2005 07/07/2010 02/25/1980 10/31/2001 03/11/1933 09/30/1916 06/04/1940 03/11/1933 03/11/1933 07/23/1923 12/16/1858 03/11/1933 03/11/1933 12130 0.0 730 0.0 0 0 0.0 1347 8.2 20 0 0.0 0 0 0.0 0 0 0.0 0 0 0.0 1547 0.0 757 0.0 620 0.0 235 0.0 83455.4 23 3 0.0 1748 0.0 144152.6 223225.0 2232 0.0 2115 0.0 518 4.0 154 7.8 1225 0.0 19 150.0 0 0 0.0 154146.5 235333.5 104738.5 075616.6 658 3.0 211 0.0 1035 8.3 85457.0 51022.0 73026.0 10 0 0.0 910 0.0 323 0.0 230 0.0 2 9 O.OI 131828.0 232042 184215 719 9.01 91017.61 .91 • 7\ 12.2( 23.3( 29.4( 33.4( 33.7( 36.1( 36.1( 36.1( 36.6( 36.6( 36.6( 37.4( 37.6( 40.7( 43.1( 44.3( 44.6( 44.6( 45.8( 46.1( 47.2( 47.7( 49.4( 50.9( 51.0( 52.3( 53.1( 53.3( 53.8( 53.8( 54.1( 55.3( 55.3( 57.4( 57.8( 58.3( 58.3( 58.3( 58.3( 58.3( 58.9( 59.0( 60.8( 61.9( 19.6) 37.4) 47.3) 53.7) 54.2) 58.1) 58.1) 58.1) 58.9) 58.9) 58.9) 60.1) 60.5) 65.5) 69.4) 71.4) 71.8) 71.8) 73.6) 74.2) 75.9) 76.8) 79.5) 82.0) 82.0) 84.2) 85.5) 85.7) 86.5) 86.5) 87.1) 89.0) 89.0) 92.4) 93.1) 93.8) 93.8) 93.8) 93.8) 93.8) 94.8) 94.9) 97.9) 99.7) Page 2 W.O. 6324-A-SC Plate C-6 -END OF SEARCH- 44 EARTHQUAKES FOUND WITHIN THE SPECIFIED SEARCH AREA. TIME PERIOD OF SEARCH: 1800 TO 2011 LENGTH OF SEARCH TIME: 212 years THE EARTHQUAKE CLOSEST TO THE SITE IS ABOUT 12.2 MILES (19.6 km) AWAY. LARGEST EARTHQUAKE MAGNITUDE FOUND IN THE SEARCH RADIUS: 7.0 LARGEST EARTHQUAKE SITE ACCELERATION FROM THIS SEARCH: 0.227 g COEFFICIENTS FOR GUTENBERG & RICHTER RECURRENCE RELATION: a-value= 1.024 b-value= 0.390 beta-value= 0.897 TABLE OF MAGNITUDES AND EXCEEDANCES: Earthquake 1 Number of Times | cumulative Magnitude | Exceeded | No. / Year 4.0 4.5 5.0 5.5 6.0 6.5 7.0 44 44 44 15 8 3 1 0.20853 0.20853 0.20853 0.07109 0.03791 0.01422 0.00474 Page 3 W.O. 6324-A-SC Plate C-7 EARTHQUAKE EPICENTER MAP MILES-PACIFIC. LLC -400 -300 -200 -100 0 100 200 300 400 500 600 W.O. 6324-A-SC Plate C-8 EARTHQUAKE RECURRENCE CURVE MILES-PACIFIC, LLC (0 a> >- (0 c > UJ o E -3 a> > « E E o 100 .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. 6324-A-SC Plate C-9 MILES-PACIFIC,_ Geographic Deagg. Seismic Hazaj for 0.00-s Spectral Accel, 0.4937 g PGA Exceedance Retum Time: 2475 year Max. significant source distance 104. km. View angle is 35 degrees above horizon Gridded-source hazard accum. in 45" intervals Soil site. Vs30(m/s)F^ 330.0 M b "D • f- O) > O) m o> IJ. CO o O [ 2012 Sep 24 15:26:05 Site Coords:-117.345 33,1721 (yellow disk) Vs30= 330.0. Max annual ExcdRate .1035E-03 (column height prop, to ExRate). Red diamonds: historical earthquakes, M>6 PSH Deaggregation on NEHRP D soii MILES-PACIFIC,_ 117.346^ W, 33.172 N. Peak Horiz. Ground Accel.>=0.4937 g Ann. Exceedance Rate .399E-03. Mean Return Time 2475 years Mean(R,M,e()) 13.7 km, 6.67, Modal (R,M,e(,) = 8.4 km, 6.95, 0.72 (from peak R,M bin) Modal (R,M,e*) - 8.4 km, 6.78, 1 to 2 sigma (from peak R,M,8 bin) Binning: DeltaR 10. km, deltaM=0.2, Deltae=1.0 O "O • I- Oi > CJ m o> o Prob. SA, PGA <median(R,M) • Eo < -2 I -2<eo<-l -1 <eo<-0.5 I -0.5<en<0 >median "^.^ 0<eo<0.5 ^--^^ 0.5 < £(, < 1 1 <eo<2 2<eo<3 200910 UPDATE 2012 Sep 24 15:26:05 Distance (R), magnitude (M), epsilon (EO.E) deaggregation for a site on soil with average vs= 330. m/s top 30 m. USGS CGHT PSHA2008 UPDATE Bins with It 0.05% contrib. omitted b •D • I- O) > OJ m 0> lx (fi ro O MILES-PACIFIC,_ Geographic Deagg. Seisinic Hazafi 8.3 for 0.00-s Spectral Accel, 0.2697 g PGA Exceedance Retum Time: 475 year Max. significant source distance 129. km. View angle is 35 degrees above horizon Gridded-source hazard accum. in 45" intervals Soil site. Vs30(m/s)F 330.0 ^5.9 M 2012 Sep 24 15:29:57 Site Coords:-117.345 33.1721 (yellow disk) Vs30= 330.0. Max annual ExcdRate .2995E-03 (column height prop, to ExRate). Red diamonds: historical earthquakes, M>6 PSH Deaggregation on NEHRP D soil MILES-PACIFIC,_ 117.346° W, 33.172 N. Peak Horiz. Ground Accel.>^0.2697 g Ann. Exceedance Rate .211E-02. Mean Return Time 475 years Mean (R,M,eo) 24.6 km, 6.67, Modal (R,M,eo) = 8.8 km, 6.65, -0.19 (from peak R,M bin) Modal (R,M,£*) = 8.8 km, 6.65, 0 to I sigma (from peak R,M,8 bin) Binning: DeltaR 10. km, deltaM-0.2, Deltae=1.0 2012 Sep 24 15:29:57 Distance (R), magnitude (M). epsilon (EO.E) deaggregation for a site on soil with average vs= 330. m/s top 30 m. USGS CGHT PSHA2008 UPDATE Bins with It 0.05% contrib. omitted APPENDIX D LABORATORY DATA GeoSoils, Inc. 60 50 LU 40 D p 30 CO a. 20 10 CL CH y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y ML MH CL-|/IL ML MH 1 1 ML MH 20 40 60 LIQUID LIMIT 80 100 Sample Depth/El. LL PL PI Rnes USCS CLASSIFICATION HA-4 1.3 35 15 20 Sandy Clay GeoSoils, Inc. ^.^..^.^ 5741 Palmer Way fi^^isMs^m'^ Carlsbad, CA 92008 '^4;5retfji;i/a Telephone: (760)438-3155 Fax: (760)931-0915 ATTERBERG LIMITS' RESULTS Project MILES-PACIFIC Number: 6324-A-SC Date: September 2012 PLATE D-1 U.S. SIEVE OPENING IN INCHES 100 95 90 85 80 75 70 H65 UJ60 ^55 UJ50 z I-45 S40 a: LU DL35 30 25 20 15 10 5 0 ^1.5 ''3/4 ^'hlB ^ U.S. SIEVE NUMBERS | 810,^16 20 30 40 50 go 100„(j200 HYDROMETER TT=Ff 11 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 COBBLES GRAVEL SAND SILT OR CUVY COBBLES coarse fine coarse medium fine SILT OR CUVY Sample Depth Range Visual Classification/uses CLASSIFICATION LL PL PI Cc Cu 9 TP-4 0.0 0-7 Silty Sand Sample Depth D100 DSO D30 D10 %Gravel %Sand %Silt %C!ay TP-4 0,0 4.75 0.196 0.097 0.0 75.3 24.7 GeoSoUsjlnc. GeoSoils, Inc. 5741 PalmerWay Carlsbad, GA 92008 Telephone: (760)438-3155 Fax; (760)931-0915 GRAIN SIZE DISTRIBUTION Project: MILES - PACIFIC Number: 6324-A-SC Date: September 2012 PLATE D-2 •CT-02-2012 11:49 From: Tc:l76093ieS15 Pa9e:3^3 Cal Land Engineering, Inc. dba Quartech Consultant Geotechnical, Environmental, and Civii Enginaering SUMMARY OF LABORATCr^Y TEST DATA GeoSoils, inc. 5741 Palmer Way, Suite D Carisbad, CA 92010 Client: Miles W.O. 6324^A-SC QCI Project No.: 12-G29-09d iDate: October 2, 2012 Summi^rized by: ABK Corr.jsi'inti'' Test Resu fci; Sample ID Sample Deptti pH CT-532 (643) CT~4;>;:> (ppnfi) TP-1 3' - 3.5' 7.34 102 Esulfete i::T-4-17 %By We}c:|ht_ D.0330 Resistivity S2 (643) (ohm-cm) ' G i -uc. 1,500 PLATE D-3 576 East Lambert Road, Brea, California 92821; Tel: 714-371" : 050; Ftx\ 714-671-1090 APPENDIX E GENERAL EARTHWORK AND GRADING GUIDELINES GeoSoils, Inc. GENERAL EARTHWORK, GRADING GUIDELINES, AND PRELIMINARY CRITERIA General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to be filled, placement of fill, installation of subdrains, excavations, and appurtenant structures or flatwork. The recommendations contained in the geotechnical report are part of these earthwork and grading guidelines and would supercede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new or revised recommendations which could supercede these guidelines or the recommendations contained in the geotechnical report. Generalized details follow this text. The contractor is responsible forthe satisfactory completion of all earthwork in accordance with provisions ofthe project plans and specifications and latest adopted code. In the case of conflict, the most onerous provisions shall prevail. The project geotechnical engineer and engineering geologist (geotechnical consultant), and/or their representatives, should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Priorto the commencementof grading, aqualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for general conformance with the recommendations ofthe geotechnical report(s), the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that an evaluation may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All remedial removals, clean-outs, prepared ground to receive fill, key excavations, and subdrain installation should be observed and documented bythe geotechnical consultant prior to placing any fill. It is the contractor's responsibility to notify the geotechnical consultant when such areas are ready for observation. GeoSoils, Inc. 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. Random or representative field compaction tests should be performed in accordance with test methods ASTM designation D 1556, D 2937 or D 2922, and D 3017, at intervals of approximately ±2 feet of fill height or approximately every 1,000 cubic yards placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted bythe contractor, with observation by a geotechnical consultant, and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction ofthe geotechnical consultant, and to place, spread, moisture condition, mix, and compact the fill in accordance with the recommendations ofthe geotechnical consultant. The contractor should also remove all non-earth material considered unsatisfactory by the geotechnical consultant. Notwithstanding the services provided by the geotechnical consultant, it is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in strict accordance with applicable grading guidelines, latest adopted codes or agency ordinances, geotechnical report(s), and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material, should be removed and disposed of off-site. These removals must be concluded prior to placing fill. In-place existing fill, soil, alluvium, colluvium, or rock materials, as evaluated by the geotechnical consultant as being unsuitable, should be Miles-Pacific, LLC ^ Appendix E Flle:e:\wp12\6300\6309a.pge GeoSoilS, InC. Page 2 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. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other structures not located prior to grading, are to be removed or treated in a manner recommended bythe geotechnical consultant. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground, extending to such a depth that surface processing cannot adequately improve the condition, should be overexcavated down to firm ground and approved by the geotechnical consultant before compaction and filling operations continue. Overexcavated and processed soils, which have been properly mixed and moisture conditioned, should be re-compacted to the minimum relative compaction as specified in these guidelines. Existing ground, which is determined to be satisfactory for support of the fills, should be scarified (ripped) to a minimum depth of 6 to 8 inches, or as directed by the geotechnical consultant. After the scarified ground is brought to optimum moisture content, or greater and mixed, the materials should be compacted as specified herein. Ifthe scarified zone is greater than 6 to 8 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 to 8 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report, or by the on-site geotechnical consultant. Scarification, disc harrowing, or other acceptable forms of mixing should continue until the soils are broken down and free of large lumps or clods, until 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 ofthe 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 otherwise bythe geotechnical consultant, the minimum width of fill keys should be equal to ^2 the height ofthe 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. Miles-Pacific, LLC _ Appendix E File:e:\wp12\6300\6309a.pge GeoSoilS, InC. Page 3 All areas to receive fill, including processed areas, removal areas, and the toes of fill benches, should be observed and approved by the geotechnical consultant prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been evaluated to be suitable by the geotechnical consultant. These materials should be free of roots, tree branches, other organic matter, or other deleterious materials. All unsuitable materials should be removed from the fill as directed by the geotechnical consultant. Soils of poor gradation, undesirable expansion potential, or substandard strength characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other approved material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill/bedrock contact. Oversized materials defined as rock, or other irreducible materials, with a maximum dimension greater than 12 inches, should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved 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. GSI anticipates that soils to be utilized as fill material forthe subject project may contain some rock. Appropriately, the need for rock disposal may be necessary during grading operations on the site. From a geotechnical standpoint, the depth of any rocks, rock fills, or rock blankets, should be a sufficient distance from finish grade. This depth is generally the same as any overexcavation due to cut-fill transitions in hard rock areas, and generally facilitates the excavation of structural footings and substructures. Should deeper excavations be proposed (i.e., deepened footings, utility trenching, swimming pools, spas, etc.), the developer may consider increasing the hold-down depth of any rocky fills to be placed, as appropriate. In addition, some agencies/jurisdictions mandate a specific hold-down depth for oversize materials placed in fills. The hold-down depth, and potential to encounter oversize rock, both within fills, and occurring in cut or natural areas, would need to be disclosed to all interested/affected parties. Once approved by the governing agency, the hold-down depth for oversized rock (i.e., greaterthan 12 inches) in fills on this project is provided as 10 feet, unless specified differently in the text ofthis report. The governing agency may require that these materials need to be deeper, crushed, or reduced to less than 12 inches in maximum dimension, at their discretion. Miles-Pacific, LLC _ Appendix E File:e:\wp12\6300\6309a.pge GeoSoilS, InC. Page 4 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 laboratory by the geotechnical consultant to evaluate it's physical properties and suitability for use onsite. Such testing 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 bythe 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 indicatesthe grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than 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 ofthe fill layer should continue until the fill materials have a uniform moisture content at, or above, optimum moisture. After each layer has been evenly spread, moisture conditioned, and mixed, it should be uniformly compacted to a minimum of 90 percent ofthe maximum density as evaluated by ASTM test designation D 1557, or as otherwise recommended by the geotechnical consultant. Compaction equipment should be adequately sized and should be specifically designed for soil compaction, or of proven reliability to efficiently achieve the specified degree of compaction. Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative compaction, or improper moisture is in evidence, the particular layer or portion shall be re-worked until the required density and/or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the geotechnical consultant. In general, perthe 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), or flatter. Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose Miles-Pacific, LLC , Appendix E File:e:\wp12\6300\6309a.pge GeoSoilS, InC. Page 5 materials with appropriate equipment. Afinal evaluation of fill slope compaction should be based on observation and/or testing of the finished slope face. Where compacted fill slopes are designed steeper than 2:1 (h:v), prior approval from the governing agency, specific material types, a higher minimum relative compaction, special reinforcement, and special grading procedures will be recommended. 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 undertaking the following: 1. An extra piece of equipment consisting of a heavy, short-shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the slopes, and extend out overthe slope to provide adequate compaction to the face ofthe slope. 2. Loose fill should not be spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re-rolling. 3. Field compaction tests will be made in the outer (horizontal) ±2 to ±8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to evaluate compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to evaluate compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix, and recompact the slope material as necessary to achieve compaction. Additional testing should be performed to evaluate compaction. SUBDRAIN INSTALLATION Subdrains should be installed in approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical consultant. The geotechnical consultant may recommend and direct changes in subdrain line, grade, and drain material in the field, pending exposed conditions. The location of constructed subdrains, especially the outlets, should be recorded/surveyed bythe project civil engineer. Drainage at the subdrain outlets should be provided by the project civil engineer. Miles-Pacific, LLC ~ ~ Appendix E File:e:\wp12\6300\6309a.pge GeoSOllS, InC. Page 6 EXCAVATIONS Excavations and cut slopes should be examined during grading by the geotechnical consultant. If directed by the geotechnical consultant, further excavations or overexcavation and refilling of cut areas should be performed, and/or remedial grading of cut slopes should be performed. When fill-over-cut slopes are to be graded, unless otherwise approved, the cut portion ofthe slope should be observed bythe geotechnical consultant prior to placement of materials for construction of the fill portion of the slope. The geotechnical consultant should observe all cut slopes, and should be notified bythe 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 ofthese conditions. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by the geotechnical consultant, whether anticipated or not. Unless otherwise specified in geotechnical and geological report(s), no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractor's responsibility. Erosion control and drainage devices should be designed bythe project civil engineer and should be constructed in compliance with the ordinances ofthe controlling governmental agencies, and/or in accordance with the recommendations ofthe geotechnical consultant. COMPLETION Observation, testing, and consultation by the geotechnical consultant should be conducted during the grading operations in order to state an opinion that all cut and fill areas are graded in accordance with the approved project specifications. After completion of grading, and after the geotechnical consultant has finished observations ofthe 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 should be undertaken as soon as practical after completion of grading. Miles-Pacific, LLC c '1 l Appendix E File:e:\wp12\6300\6309a.pge GeoSollS, InC. Page 7 JOB SAFETY General At GSI, getting the job done safely is of primary concern. The following is the company's safety considerations for use by all employees on multi-employer construction sites. On-ground personnel are at highest risk of injury, and possible fatality, on grading and construction projects. GSI recognizes that construction activities 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 contractor, and GSI personnel must be maintained. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented forthe safety of field personnel on grading and construction projects: Safety Meetings: GSI field personnel are directed to attend contractor's regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for, and are to be worn by GSI personnel, at all times, when they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing amber beacons, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. Test Pits Location, Orientation, and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technician's safety. Efforts will be made to coordinate locations with the grading contractor's authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of current traffic. The contractor's authorized representative (supervisor, grade checker, dump man, operator, etc.) should direct excavation of the pit and safety during the test period. Of paramount concern should be the soil technician's safety, and obtaining enough tests to represent the fill. Miles-Pacific, LLC ^ Appendix E File:e:\wp12\6300\6309a.pge GeoSollS, InC. Pagg 8 Test pits should be excavated so that the spoil pile is placed away from oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center ofthe test pit. This zone is established for safety and to avoid excessive ground vibration, which typically decreases test results. When taking slope tests, the technician should park the vehicle directly above or belowthe test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively keep all equipment at a safe operational distance (e.g., 50 feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter ofthe fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads, cut and fill areas or other factors that may affect site access and site safety. In the event that the technician's safety is jeopardized or compromised as a result of the contractor'sfailureto complywith any ofthe above, the technician is required, by company policy, to immediately withdraw and notify his/her supervisor. The grading contractor's representative will be contacted in an effort to affect a solution. However, in the interim, no further testing will be performed until the situation is rectified. Any fill placed can be considered unacceptable and subject to reprocessing, recompaction, or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor bring this to the technician's attention and notify this office. Effective communication and coordination between the contractor's representative and the soil technician is strongly encouraged in order to implement the above safety plan. Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of instability, has any loose rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. Miles-Pacific, LLC . Appendix E File:e:\wp12\6300\6309a.pge GeoSOllS, InC. Page 9 All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance with Cal/OSHA and/or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down" on the equipment. If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his/her supervisor. The contractor's representative will be contacted in an effort to affect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify Cal/OSHA and/or the proper controlling authorities. Miles-Pacific, LLC ^ Appendix E Flle:e:\wp12\6300\6309a.pge GeoSoilS, InC. Page 10 Toe of slope as shown on grading plan Natural slope to be restored with compacted Proposed grade Backcut varies 2-foot minimum in bedrock or rapproved earth material Bedrock or approved native material Subdrain as recommended by geotechnical consultant NOTES: 1. Where the natural slope approaches or exceeds the design slope ratio, special recommendations would be provided by the geotechnical consultant. 2. The need for and disposition of drains should be evaluated by the geotechnical consultant, based upon exposed conditions. Gee00iiSt Me, FILL OVER NATURAL (SIDEHILL FILL) DETAIL Plate E-7 Cut/fill contact as shown on grading plan Proposed grade H = height of siope Subdrain as recommended by geotechnical consultant Bedrock or approved native material NOTE: The cut portion of the slope should be excavated and evaluated by the geotechnical consultant prior to construction of the fill portion. GanS^MiT) Inc. FILL OVER CUT DETAIL Plate E-8 Natural slope Proposed finish grade Typical benching (4-foot minimum) Compacted stablization Bedrock or other approved native material If recommended by the geotechnical consultant, the remaining cut portion of the slope may require removal and replacement with compacted fill. Subdrain as recommended by geotechnical consultant NOTES: I Subdrains may be required as specified by the geotechnical consultant. 2 W shall be equipment width (15 feet) for slope heights less than 25 feet. For slopes greater than 25 feet, W shall be evaluated by the geotechnical consultant. At no time, shall W be less than H/2, where H is the height of the slope. Ge0&0^s, Imc* STABLIZATION FILL FOR UNSTABLE MATERIAL EXPOSED IN CUT SLOPE DETAIL Plate E-9 Natural grade Proposed pad grade Bedrock or approved native material 3- to 7-foot minimum* overexcavate and recompact per text of report Typical benching CUT LOT OR MATERIAL-TYPE TRANSITION Proposed pad grade Natural grade Bedrock or approved native Typical benching material (4-foot minimum) 3- to 7-foot minimum* overexcavate and recompact per text of report * Deeper overexcavation may be recommended by tlie geoteciinicai consultant in steep cut-fill transition areas, sucin tfiat tine underlying topograpfiy is no steeper than 31 (HV) CUT-FILL LOT (DAYLIGHT TRANSITION) TRANSITION LOT DETAILS Plate E-12 MAP VIEW NOT TO SCALE SEE NOTES 4-inch perforated subdrain pipe (transverse) Direction of drainage 4-inch perforated subdrain pipe (longitudinal) Coping 2-inch-thick sand layer CROSS SECTION NOT TO SCALE SEE NOTES VIEW Coping Pool encapsulated in 5-foot thickness of sand Vapor retarder 6-inch-thick gravel layer 4-inch perforated subdrain pipe layer Gravity-flow nonperforated subdrain pipe ^Concrete cut-off wall-Vapor retarder Perforated subdrain pipe NOTES: 1. 6-inch-thick, clean gravel (% to 1)2 inch) sub-base encapsulated in Mirafi MON or equivalent, underlain by a 15-mil vapor retarder, with 4-inch-diameter perforated pipe longitudinal connected to 4-inch-diameter perforated pipe transverse. Connect transverse pipe to 4-inch-diameter nonperforated pipe at low point and outlet or to sump pump area. 2. Pools on fills thicker than 20 feet should be constructed on deep foundations; otherwise, distress (tilting, cracking, etc.) should be expected. 3. Design does not apply to infinity-edge pools/spas. GmSoiMflne. TYPICAL POOL/SPA DETAIL Plate E-17 SIDE VIEW Test pit TOP VIEW Flag Gm$0^^ fnc. TEST PIT SAFETY DIAGRAM Plate E-20