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36305
iuwu�hr �, IE 3 5c , ,Ie, � 3(93oS F6LI I* 0 El received JAN 2 5 ZGIZ City of la 6bt.i to Planning Depadir-Olt REPORT OF GEOTECHNICAL / GEOLOGIC STUDY UPDATE PROPOSED RENDITIONS AT PALIZADA TENTATIVE TRACT MAP NO. M305 SOUTHEAST QUADRANT OF THE INTERSECTION OF AVENUE 60 AND MONROE STREET CITY OF LA QUINTA RIVERSIDE COUNTY, CALIFORNIA PROJECT NO.: 504 -A05 REPORT NO.: 9 DECEMBER 23, 2011 SUBMITTED TO: KB HOME SOUTHERN CALIFORNIA COASTAL DIVISION 36310 INLAND VALLEY DRIVE WILDOMAR, CA 92595 PREPARED BY: HILLTOP GEOTECHNICAL, INC. 786 SOUTH GIFFORD AVENUE SAN BERNARDINO, CA 92408 a • 0 0 a HILLTOP GEOTECHNICAL INCORPORATED December 23, 2011 786 S. GIFFORD AVENUE • SAN BERNARDINO • CALIFORNIA 92408 hilltopg ®hgeotech.com • FAX 909 - 890 -9055 • 909 -890 -9079 KB Home Southern California. Coastal Division 36310 Inland Valley Drive Wildomar, CA 92595 Attention: Mr. Chris Mounts Project No.: 504 -A05 Report No.: 9 Subject: Report of Geotechnical / Geologic Study Update, Proposed Renditions at Palizada, Tentative Tract Map No. 36305, Southeast Quadrant of the Intersection of Avenue 60 and Monroe Street, City of La Quinta, Riverside County, California. References: 1. Hilltop Geotechnical, Inc., March 8, 2007, Geotechnical Report of Grading, Proposed Residential Subdivisions, Tentative Tract Nos. 31732 and 31733, Southeast porner of Monroe Street and Avenue 60, City of La Qu.'mta,, Riverside County, California, Project No.: 504 -005, Report No.:�1. 2. Hilltop Geotechnical Inc. Aril' 26 2,0 "06 Zl dated P > P I P. Geotechnical Report, Proposed ResidentialSubdivisions, Pi-ado Del Sol, Tract Nos. 31732 and 31733, Southeast Corner of Monroe Street and Avenue 60,,,Ci-ty of La .Quinta, Riverside County, California, Project No.- 504 =A05, Report No.: 8. �nc. December 7 '200.5 -Street 3. Hilltop Geotechnical , , , Grading Recommenda Z. Tentative Tract Nos,-33 -1- 732_ &_ 31733, Southeast Co ner of 'Monroe Street and Avenue 60 La Quinta Area of Ri, rside County; ,Calif ornia.,,P"roject "1No.c 5'04- A05, Report No T 504 -A05.9 December 23, 2011 Page 2 4. Hilltop Geotechnical, Inc., November 28, 2005, Supplemental Geotechnical Recommendations for Foundations on Expansive Soils, Proposed Residential Subdivisions, Tentative Tract Nos, 31732 & 31733, Southeast Corner of Monroe Street and Avenue 60, La Quinta Area of Riverside County, California, Project No.: .504-A05; Report No.: 6. 5. Hilltop Geotechnical, Inc., July 18, 2005, Observation of Environmental Cleanup, Contaminated Soil and One 55- Gallon Oil Drum, Proposed Tract Nos. 31732 and 31733, Southeast Corner' of Avenue 60 and Monroe Street, La Quinta Area, Riverside. County, California, Project No.: 504 -A05, Report No. 5. 6. Hilltop Geotechnical, Inc., June . 2, 2005,) Report of Percolation Testing, Proposed Residential Subdivisions, Tentative Tract Nos; 31732 & 31733, Southeast Corner of Monroe Street and Avenue 60, La Quinta Area of Riverside County, California, Project No.: 504 -A05, Report No.: 4. 7. Hilltop Geotechnical, Inc., May 6, 2005, Phase II Environmental Sampling and Analysis, Proposed Tract Nos. 31732 and 31733, Southeast Corner of Avenue 60 and Monroe Street, La Quinta Area, Riverside County, California, Project No.: 504 -A05, Report No.: 3. 8. Hilltop Geotechnical, Inc., April 22, 2005, Report of Geotechnical Study, Proposed . Residential Subdivisions, Tentative Tract Nos, 31732 & 31733, 'Southeast Corner of Monroe Street and Avenue 60, La Quinta Area of Riverside County, California, Project No.: 504 -A05, Report No.: 2. 9. Hilltop Geotechnical, Inc., April 21, 2005, Environmental Assessment, Proposed Tract Nos. 31732 and 31733, Southeast Corner of Avenue 60 and Monroe Street, La Quinta Area, Riverside County, California; Project No.: 504 -A05, Report No.. 1. 10. City of La Quinta, August 4, 2011, ECN 11063 Renditions at Palizada SP 11 -086: TT 36305- SDP11 -918 SEC Ave 60 and Monroe - Project Review for Entitlement. HILLTOP GEOTECHIVICAL, INC. r 504 -A05.9 Gentlemen: December 23, .2011 Page 3 11. AMS Consulting, May 25, 2011 with no Corrections, Tentative Tract Map No. 36305, Renditions at Palizada in the City of La Quinta, County of Riverside, State of California, Sheet l of 6 through Sheet 6 of 6. 12. Technical. References - See Appendix `B.' According to your request, we have completed an update of the geotechnical / geologic study for the design and construction of the proposed single family residential development. We are presenting, herein, our findings and recommendations. This geotechnical / geologic study update supercedes the recommendations presented in the Reference Nos. 1, 2, 3, 4, and 8 reports in their entirety. The findings of this study indicate that the project site is suitable for the proposed single family residential development provided the recommendations presented in the attached report are complied with and incorporated -into the design and construction of the project. Copies of this updated report should be forwarded to your other consultants for the project (i.e., Civil Engineer, Architect, Structural Engineer, etc.) as needed to implement the recommendations presented. The required number of the original, wet ink signed reports should be saved.for submittal, along with the other required documentation to the appropriate agency having jurisdiction over the project for permitting purposes. If you have any questions after reviewing the findings and recommendations contained in the attached report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. y submitted, GEOTECHNFCAL, INC. Mark Hulett, CEG No. 1623 President Date Signed: HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 4 MH/DLC /ah Distribution: (4) Addressee Via U.S. Postal Service (1) Addressee pdf copy on CD Via U.S. Postal Service HILLTOP GEOTECHNICAL, INC. s 504 -A05.9 December 23, 2011 Page i TABLE OF CONTENTS Section Title Page No. INTRODUCTION .................. ............................... 1 AUTHORIZATION ............ ............................... 1 PURPOSE AND SCOPE OF STUDY ............................ 2 PREVIOUS SITE STUDIES .... ............................... 5 PROJECT DESCRIPTION / PROPOSED DEVELOPMENT ......... 6 FIELD EXPLORATION AND LABORATORY TESTING ................. 7 FINDINGS........................ ............................... 7 SITE DESCRIPTION .......... ............................... 7 ENGINEERING GEOLOGIC ANALYSIS ........................ 8 Regional Geologic Setting ........ ...................... 8 Local Subsurface Conditions ............................. 10 Earth Materials Description ........................ 10 Groundwater .... ...... .. ................... 10 Surface Water .... ............................... 11 Site Variations 11 Faulting and Regional Seismicity ......................... 12 Secondary Seismic Hazards ................:............ 16 Landslide ........ ............................... 16 Liquefaction ...... ............................... 16 Liquefaction Program ....................... 17 Input Parameters ........................... 18 Liquefaction Analyses ....................... 19 Results and Conclusions ..................... 19 Seismically Induced Subsidence ..................... 21 Lateral Spreading . ............................... 22 Seiching .......................... ........ 22 Tsunamis ......... ............................... 22 Lurching ............... ... 22 OTHER GEOLOGIC HAZARDS ................................ 23 Flooding.............. ............................... 23 CONCLUSIONS AND RECOMMENDATIONS ........................ 23 GENERAL ................. ............................... 23 HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page ii TABLE OF CONTENTS Section Title Page No. SITE PREPARATION RECOMMENDATIONS ................... 26 General............... ............................... 26 Final Grading Plan Review .............................. 27 Clearing and Grubbing .. ............................... 28 Excavation Characteristics .............................. 28 Suitability of On -Site Materials as Fill .................... 29 Removal and Recompaction ......... .................. 29 Import Material ........ ............................... 32 Fill Placement Requirements ............... . ........... 33 Compaction Equipment .. ............................... .33 Shrinkage, Bulking, and Subsidence ...................... 33 Abandonment of Existing Underground Lines ............... 35 Fill Slopes ............. ............................... 36 CutSlopes ............. ............................... 37 Fill- Over -Cut Slopes .... ............................... 37 Loose Material on Slope Face ............................ 37 Slope Creep ........... ............................... 37 Slope Protection ........ ............................... 38 Protection of Work ...... ............................... 39 Observation and Testing . ............................... 39 Earth Material Expansion Potential ...................... 41 Earth Material Corrosion Potential ....................... 41 2010 CBC SEISMIC DESIGN CRITERIA ....................... 41 FOUNDATION DESIGN RECOMMENDATIONS ................ 44 General ............... ............................... 44 Deepened Conventional Foundations for Retaining Walls an Decorative Perimeter Block Walls ................ 45 Foundation Size .. ............................... 45 Depth of Embedment ............................. 45 Footing Setback ... ............................... 46 Bearing Capacity .. ............................... 46 Settlement ....... ............................... 47 `Slab -on- Ground Foundation' System ...................... 47 `Post- Tensioned Slab -on- Ground' System ................... 48 Lateral Capacity ....... ............................... 50 Interim Foundation Plan Review ......................... 52 HILLTOP GEOTECHNICAL, INC. r • • - n'ti 504 -A05.9 December 23, 2011 Page iii TABLE OF CONTENTS Section Title Page No. Final Foundation Design Recommendations ................ 52 Foundation Excavations . ............................... 52 SLAB -ON- GRADE FLOOR RECOMMENDATIONS ................ 53 `Slab -on- Ground Foundation' System ...................... 54 `Post- Tensioned Slab -on- Ground' System ................... 55 Vapor Barrier / Moisture Retarder Recommendations ........ 56 EXTERIOR CONCRETE FLATWORK .......................... 57 RETAINING WALL RECOMMENDATIONS .................... 59 Static Lateral Earth Pressures ........................... 59 Seismic Lateral Earth Pressure ........................... 60 Foundation Design ...... ............................... 61 Subdrain.............. ............................... 62 Backfill ............... ............................... 63 V -Drain Design ................... .................. 64 Observation and Testing.. ................. ............ 64 Reinforced Earth Retaining Walls ........................ 66 CORROSION POTENTIAL EVALUATION ...................... 66 Concrete Corrosion ..... ............................... 66 Metallic Corrosion ...... ............................... 68 Salt Crystallization Exposure ............................ 69 SWIMMING POOL RECOMMENDATIONS ..................... 70 SLOPE STABILITY EVALUATION ............................ 72 PRELIMINARY PAVEMENT RECOMMENDATIONS ............. 73 POST - GRADING CRITERIA ... ..:............................ 79 SLOPE MAINTENANCE AND PROTECTION RECOMMENDATIONS . ............................... 79 UTILITY TRENCH RECOMMENDATIONS ..................... 81 Trench Excavation ...... ............................... 82 Utility Line Foundation Preparation ................. ... 83 Bedding Requirements .. ............................... 85 Trench Zone Backfill .... ............................... 86 FINISH SURFACE DRAINAGE RECOMMENDATIONS .......... 86 PLANTER RECOMMENDATIONS ............................ 87 LIMITATIONS ........ ......... ............................... 88 REVIEW, OBSERVATION, AND TESTING ..................... 88 HILLTOP GEOTECHNICAL, INC:- 504 -A05.9 December 23, 2011 Page iv TABLE OF CONTENTS Section Title Page No. UNIFORMITY OF CONDITIONS ............................. 88 CHANGE IN SCOPE .. ..... ............................... 89 TIME LIMITATIONS ......... ............................... 89 PROFESSIONAL STANDARD . ............................... 89 CLIENT'S RESPONSIBILITY .. ............................... 90 APPENDIX A Hilltop Geotechnical, Inc., April 22, 2005, Report of Geotechnical Study, Proposed Residential Subdivisions, Tentative Tract Nos, 31732 & 31733, Southeast Corner of Monroe Street and Avenue 60, La Quinta Area of Riverside County, California, Project No.: 504 -A05, Report No.: 2. `Exploratory Excavation Plan,' Plate Nos 1a and lb. `Subsurface Exploration Log,' Plate No. 2. `Subsurface Exploration Log,' Plate Nos. 3 through 9. `Summary of Laboratory Test Results,' `Expansion Index Test Result (ASTM D4829 Test Method),' Plate No. 10. `Soluble Sulfate Test Results (California Test Method No. 417),' Plate No. 10. `Percent Passing #200 Sieve Test (ASTM D1149 Test Method),' Plate No. 11. `Chemical Test Results,' Plate No. 12. `Consolidation Test Result (ASTM D2435),' Plate No. 12. `Consolidation Test Result,' Plate No. 13. `Maximum Dry Density / Optimum Moisture Content Test Results,' Plate No. 14. `Atterberg Limit Test Result,' Plate No. 15. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page v TABLE OF CONTENTS Section Title Page No. APPENDIX A (Cont.) Hilltop Geotechnical, Inc., March 8, 2007, Geotechnical Report of Grading, Proposed Residential Subdivisions, Tentative Tract Nos. 31732 and 31733, Southeast Corner of Monroe Street and Avenue 60, City of La Quinta, Riverside County, California, Project No.: 504 -005, Report No.: 1. `Summary of Laboratory Test Results,' `Maximum Dry Density / Optimum Moisture Content Test Results,' Plate No. 67. `Percent Passing #200 Sieve Test (ASTM D1149 Test Method),' Plate No. 68. . `Expansion Index Test Result (ASTM D4829 Test Method),' Plate No. 69. `Soluble Sulfate Test Results (California Test': ._ 417),' Plate No. 70. `Soluble .Chloride Test Results (California Test 422),' Plate No. 71. `Expansion Index Test Results (ASTM D4829 Test Method),' Plate Nos. 72 through 74. `Soluble Sulfate Test Results (California Test 417),' Plate Nos. 74 through 93. `Soluble Chloride Test Results (California Test 422),' Plate Nos. 93 through 95. APPENDIX B TECHNICAL REFERENCES . ............................... B -1 APPENDIX C `Liquefaction Analysis, Water Depth = 24.0 ft.' ............. Plate C -1 `Liquefaction Analysis, Water Depth = 5.0 ft.' .............. Plate C -2 .'Dry Sand Settlement Analysis, Water Depth = 24.0-ft ......... Plate C -3 Iq 04 HILLTOP GEOTECHNICAL, INC. REPORT OF GEOTECHNICAL /GEOLOGIC STUDY UPDATE PROPOSED RENDITIONS AT PALIZADA TENTATIVE TRACT MAP NO. 36305 SOUTHEAST QUADRANT OF THE INTERSECTION OF AVENUE 60 AND MONROE STREET CITY OF LA QUINTA RIVERSIDE COUNTY, CALIFORNIA PROJECT NO.: 504 -A05 REPORT NO.: 9 DECEMBER 23, 2011 INTRODUCTION AUTHORIZATION This report presents results of the updated geotechnical / geologic study for the subject site for the proposed single family residential development to be located in the southeast quadrant of the intersection of Avenue 60 and Monroe Street in the City of La Quinta, Riverside County, California. The general location of the subject site is indicated on the `Site Location Map,' Figure No. 1. Authorization to perform this study was in the form of a written proposal dated August 31, 2011, Proposal No.: P11150, and an `Addendum to Contract', dated December 12, 2011, Addendum No.: 002, Contract No.: 5057864 OS 002, from KB Home Southern California, Coastal Division (Client) to' Hilltop Geotechnical, Inc. (HGI) ( Geotechnical / Geologic Consultant). HILLTOP GEOTECHNICAL, INC. I 504 -A05.9 December 23, 2011 Page 2 PURPOSE AND SCOPE OF STUDY The scope of work performed for this study was designed to determine and evaluate the surface and subsurface conditions of the subject site with respect to geotechnical characteristics, including potential geologic hazards that may effect the development of the site, and to provide geotechnical recommendations and criteria for use in the design and construction of the proposed development. The scope -of work included the following: • Review of locally and easily available published and unpublished soil, geologic, and seismologic reports and data for the area (see References in Appendix `B'), including previous geotechnical and geologic reports prepared by HGI (Reference Nos. 1, 2, 3, 4, and 8 noted on the cover letter for this report), flood hazard maps, well data, etc. to ascertain earth material, geologic, and hydrologic conditions of the area. • Telephone conversations with the client and/or representatives of the client. • Site reconnaissance. • Review of the 'subsurface exploration performed for the Reference No.� 8 ` Geotechnical 'Study' characterizing earth materials, geologic, and groundwater conditions that could influence the proposed development. • Review of the laboratory testing performed for the Reference Nos. 1 and 8 `Report of Grading' and ` Geotechnical Study,' respectively, on selected earth material samples considered representative of the subsurface conditions to determine the engineering properties and characteristics. • Define the general geology of the subject site and evaluate potential geologic hazards which would have an effect on the proposed site development. • Determine seismic classification of the site to meet the requirements of the 2010 California Building Code (CBC), effective on January 1, 2011. • Engineering analysis offield and laboratory data presented in the Reference Nos. 1 and 8, `Report of Grading' and ` Geotechnical Study,' respectively, to provide a basis for updated geotechnical and geologic conclusions and HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 3 recommendations regarding site grading and foundation, floor slab, retaining wall, pavement, etc. design parameters. • Preparation of this report to present the updated geotechnical and geologic conclusions and recommendations for the proposed site development. This report presents our conclusions and/or recommendations regarding: • The geologic setting of the site. • Potential geologic hazards (including landslides, seismicity, faulting, liquefaction potential, etc.) M • General subsurface earth conditions. • Presence and effect of expansive, collapsible, and compressible earth materials. • Groundwater conditions within the depth of our subsurface study. • Excavation characteristics of the on -site earth materials. • Characteristics and compaction requirements of proposed fill and backfill materials. • Recommendations and guide specifications for earthwork. • Seismic design coefficients for structural design purposes. • Types and depths of foundations. • Allowable bearing pressure and lateral resistance for foundations. • Estimated total and differential settlements. • Preliminary corrosion potential evaluation for concrete and buried metal in direct contact with the on -site earth materials. • Permanent cut and fill slope recommendations. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page' 4 • Utility trench excavation and backfill recommendations. • Slope maintenance and protection recommendations. • Preliminary pavement recommendations. The scope of work performed for this geotechnical / geologic study update did not include any testing of earth materials or groundwater for environmental purposes, an environmental assessment ofthe property, or opinions relating to the possibility of surface or subsurface contamination by hazardous or toxic substances. In addition, evaluation of on -site storm water retention systems for the proposed development was not part of this geotechnical / geologic study update. This geotechnical update report was prepared for the exclusive use of YB Home Southern California, Coastal Division and their consultants for specific application to the design and construction of the proposed single family residential development in accordance with generally accepted standards of the geotechnical and geologic professions and generally accepted geotechnical (soil and foundation) engineering principles and practices at the time this report was prepared. Other warranties, implied or expressed, are not made. Although reasonable effort has been made to obtain information regarding geotechnical / geologic and subsurface conditions of the site, limitations exist with respect to knowledge of unknown regional or localized off -site conditions which may have an impact at the site. The conclusions and recommendations presented in this report are valid as of the date of this report. However, changes in conditions of a property can•occur with passage of time, whether they are due to natural processes or to works of man on this and/or adjacent properties. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 5 If conditions are observed or information becomes available during the design and construction process which are not reflected in this report, HGI, as Geotechnical / Geologic Consultant of record for the project, should be notified so that supplemental evaluations can be performed and conclusions and recommendations presented in this report can be verified or modified in writing, as necessary. Changes in applicable or appropriate standards of care in the geologic / geotechnical professions occur, whether they result from legislation or the broadening of knowledge and experience. Accordingly, the conclusions and recommendations presented in this report may be invalidated, wholly or in part, by changes outside the influence of the project Geotechnical / Geologic Consultant which occur in the future. PREVIOUS SITE STUDIES Prior to this report, previous subsurface explorations, geotechnical / geologic studies, environmental assessments, and grading observations and testing have been performed on the subject site. The results of those studies were presented in the Reference Nos. 1 through 9 studies noted on the first and second pages of the cover letter for this report. The results of the previous studies correspond with the results of this geotechnical update report, recognizing the normal variations in subsurface materials within natural alluvial deposits and man made fills on the site. The information presented in the reference reports is not repeated herein with the exception of the boring logs and laboratory test results from the Reference No. 8 ` Geotechnical Study' and the results of the laboratory test performed for the Reference No. 1 `Report of Grading' which are included for reference in Appendix `A' of this geotechnical update report. Reference is made to inform the reader of the existence of the reports. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 6 PROJECT DESCRIPTION / PROPOSED DEVELOPMENT As part of our study, we have discussed the project with Mr. Chris Mounts, a consultant for KB Homes Southern California, Coastal Division, the client for the project. We also have been provided with the Reference No. 11 `Tentative Tract Map' noted on the third page of the cover letter for this report. In addition, we have reviewed the Reference Nos. 1, 2, 3, 4, and 8 reports which were previously prepared for the subject site. Based on information presented to this firm, it is our understanding that the proposed project will consist of 418 lots with 12,800 single family residential units, a HMA Amenity (Lot 419), a well site (Lot 420), private streets (Lots `A' through `R'), Public Streets (Lots `S' through `U'), Retention Basins (Lots `AA'through `GG'.), and various open spaces (Lots `HH' through `SSS'). The single family residential units are assumed to be multi -story structures with concrete slab -on -grade ground level floors and no basements or subterranean construction. The maximum dead loads plus frequently applied live loads for the structures are assumed to be light and will not exceed 3,000 pounds per lineal foot (plf) for wall footings and 75 kips for column footings. Cuts and fills of less than 5.0 feet are anticipated to achieve proposed finish pad grades for the residential lots. Maximum cuts for the open space / retention basins will be less than 10 feet. Fill and cut slope ratios of 2H: 1V (Horizontal to Vertical) and maximum vertical heights of less than 10 are proposed. Minor, low height, retaining walls may be required for the proposed residential development. The subject site has previously been rough graded for single family residential tracts. The rough grading was observed and tested by representatives of HGI (See the Reference No. 1 `Report of Grading' noted on the first page of the cover letter for this report). t HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 7 The above project description and assumptions were used as the basis for the review of the previous reports for the subject property, the engineering analysis, and the conclusions and recommendations presented in this report. HGI should be notified if structures, foundation loads, grading, and/or details other than those represented herein are proposed for final development of the site so a review can be performed, a supplemental evaluation made, and revised recommendations submitted, if required. y FIELD EXPLORATION AND LABORATORY TESTING` No additional field exploration or laboratory testing were performed as part of this updated report for the subject development. A site reconnaissance was performed on December 16, 2011 as part of the update report for the subject development. FINDINGS SITE DESCRIPTION The subject property comprises approximately 81 acres, is rectangular in shape, and approximately 1,340 feet by 2,625 feet in plan dimension as shown on the Reference No. 11 `Tentative Tract Map' noted on the third page of the cover letter for this report. The subject property is located in the southeast quadrant of the intersection of Monroe Street and Avenue 60 in the City of La Quinta, Riverside County, California. The subject property is located in the west one -half of the northwest one - quarter of Section 35, Township 6 South, Range 7 East of the San Bernardino Principle Meridian. The center of the subject tract is located at approximately Latitude: 33.6092° North, Longitude: 116.2312° West. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 8 At the time of the site reconnaissance performed for this geotechnical / geologic study update, the entire site had a chain link fence around it and no access was available to enter the site. The subject site appeared to be as it was left after rough grading was completed in the fall of 2006. No structures were present on the subject site at the time of the field reconnaissance performed for this geotechnical / geologic study update. The site was covered with a dense growth of native grass, forbs, and brush. There were several small trees growing in the northwest portion of the subject site. ENGINEERING-GEOLOGIC ANALYSIS Regional Geologic Setting The subject project site is situated in the central portion of the Coachella Valley. The Coachella and Imperial Valleys and the Colorado River Delta region in southern California and northern Mexico are all portions of a larger, tectonically controlled structural feature known as the Salton Trough. This deep, structural basin has resulted from lateral movement away from spreading centers in the southern part of the trough, and transform (strike -slip) movement, which characterizes the San Andreas fault system, along the northeast side of the valley. Depths to crystalline basement rock in the Salton Trough exceed 18,000 feet in the Imperial Valley area and are on the order of several thousand feet in the center of the Coachella Valley (Dibblee, 1954). Marine, fossil- bearing, sedimentary rocks visible in outcrops around basin margins attest to advancement of Gulf of California waters as far north as the San Gorgonio Pass region in early Pliocene time. Younger sediments include thick sequences of predominantly fine - grained, lacustrine strata deposited in several late Cenozoic lakes that have existed intermittently in the trough. The most recent lake is the Salton Sea, resulting originally from a Colorado River dike failure near the turn of the century and HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 9 maintained by runoff from vast, agricultural irrigation in the Imperial and Coachella Valleys. The Little San Bernardino Mountains bound most of the northern Coachella Valley, and are assigned to the Transverse Ranges. The Transverse Ranges include the San Bernardino and San Gabriel Mountains, and are predominantly composed of Cretaceous -age and older igneous and metamorphic rocks. The south face of the Little San Bernardino Mountains rises abruptly from the floor of the Coachella Valley to elevations locally exceeding 5,000 feet above sea level. Steeply sloped canyons and ridges in this range have been source areas for coarse - grained alluvial fill in the valley since at least early Pliocene time. The San Andreas fault zone is the dominant structural element in the Coachella Valley. Extending over 650 miles from the Gulf of California to the vicinity of Cape Mendocino in northwestern California, the San Andreas fault zone often comprises a strip up to several miles wide of subparallel, branching and anastomosing fault strands. The fault zone accommodates mostly right- lateral strike -slip movement with generally small vertical components. Research has indicated the fault is divisible into several discrete segments along its length based upon differing geologic and seismic characteristics (Weldon and Matti, 1986). Each discrete segment appears to react to tectonic stress more or less independently from the others, and have its own characteristic, large earthquake with differing maximum magnitude potential and recurrence interval (e.g., in Petersen, et al., 1996). The site is underlain by Quaternary aged lake deposits derived from extinct Lake Coahuila. The site is topographically located approximately 70 feet lower than the lake's high shoreline. The thickness of lake deposits beneath the site are interpolated to be approximately 60 to 70 feet and are composed mainly of fine silty HILLTOP GEOTECHNICAL, INC. • • • • • • • • • • w • • w w • • • • • w • w • • • • • w • • • • • • • • • • • • • • 504 -A05.9 December 23, 2011 Page 10 sands and sandy silts with thin clay beds and lenses. The general geology in the area of the subject site is shown on the `Regional Geology Map,' Figure No. 2a, and the `Regional Geology Map Legend,' Figure No. 2b. Local Subsurface Conditions Earth Materials Description: Presented as follows are brief descriptions of the earth materials encountered in the exploratory excavations performed for the Reference No. 8 `Geotechnical Study,' noted on the second page of the cover letter for this report. More detailed descriptions of the earth materials encountered are presented on the `Subsurface Exploration Log,' Plate Nos. 3 through 9, presented in Appendix `A.' The earth material strata, as shown on the logs, represent conditions at the actual exploratory excavation locations. Other variations may occur beyond and/or between the excavations. Lines of demarcation between earth materials on the logs represented the approximate boundary between the material types; however, the transition may be gradual. The site materials encountered during the field exploration performed for the referenced `Geotechnical Study' were identified as quaternary lake deposits (Ql). The quaternary lake deposits (Ql) consisted of fine sandy silts (ML), sandy clays (CL), silty fine sands (SM), silty fine to medium sands (SM), and slightly silty fine to medium sands (SP /SM). These strata were generally gray, brown, gray brown or olive brown in color, moist near the surface to wet with depth, and very loose to dense in relative density or medium stiff to very stiff in consistency. Groundwater: Groundwater was encountered at a depth of 24 feet below the existing ground surface at the location of boring B -4 at the time the field study was performed for the referenced `Geotechnical Study.' HILLTOP GEOTECHNICAL, INC. 0 0 w 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 • • 0 Legend for Geologic Symbols and Units Separates geologic -map units. Solid where meets map- accuracy standard; dashed where may not meet map- accuracy standard; • , L. AjLjL u i i dotted where concealed Contact -- Separates terraced alluvial units where younger alluvial 20 unit is incised into older alluvial unit; hachures at base of slope, — point toward topographically lower surface. Solid where meets T . • • • , map- accuracy standard; dashed where may not meet map- accuracy �— ♦ standard Fault—Solid where meets map- accuracy standard; dashed where may not meet map accuracy standard. Dotted where concealed by mapped covering unit; queried where existence uncertain. Hachures indicate scarp, with hachures on downdropped block. Paired arrows indicate relative movement; single arrow indicates direction and amount of fault -plane dip. Bar and ball on down - thrown block. Reference: California Department of Conservation, Division of Mines and Geology, 1965 (Third Printing 1976), Olaf P. Jenkins Edition, Geologic Map of California, Santa Ana Sheet, Scale 1:250,000. REGIONAL GEOLOGY MAP LEGEND By: AH Date: 12/11 HILLTOP GEOTECHNICAL IDEOFPOOATED Project No.: 504 -A05.9 Figure No.: 2b Qs - Dune sands (Holocene). Qo I Qal - Alluvium (Holocene). Q1;�= Ql - Alluviva lake deposits (Holocene). Qc -Non marine (Pleistocene). Gr - Granite, adamellite, tonalite & diorite (Mesozoic). Reference: California Department of Conservation, Division of Mines and Geology, 1965 (Third Printing 1976), Olaf P. Jenkins Edition, Geologic Map of California, Santa Ana Sheet, Scale 1:250,000. REGIONAL GEOLOGY MAP LEGEND By: AH Date: 12/11 HILLTOP GEOTECHNICAL IDEOFPOOATED Project No.: 504 -A05.9 Figure No.: 2b 504 -A05.9 December 23, 2011 Page 11 Per the referenced ` Geotechnical Study,' groundwater data from a well located less than 1/4 -mile south of the site, State Well No. 06S07E12H03S, indicated depth to groundwater as shallow as 7.2 feet below the ground surface. This data was the oldest groundwater information available in the area (data gathered over the past 10 years) and was obtained through a telephone conversation on May 31, 2005, with Mr. Alan Harrell, an engineering technician at the Coachella Valley Water District. Based on proposed lot grading and the inferred groundwater depths, groundwater should not be a factor for project design or long -term performance of the. =:subject development. Surface Water: Surface water was not observed on the subject site at the time the field reconnaissance was performed for this geotechnical / geologic study update. Site Variations: Based on results of our subsurface exploration and experience, variations in the continuity and nature of surface and subsurface conditions should be anticipated. Due to uncertainty involved in the .nature and depositional characteristics of earth materials at the site, care should be exercised in extrapolating or interpolating subsurface conditions between and beyond the exploratory excavation locations. Groundwater observations were made in the exploratory excavations at the times and under conditions stated on the boring logs performed for the referenced ` Geotechnical Study.' This data has been reviewed and interpretations made in the text in other sections of this report. However, it should be noted that fluctuations HILLTOP GEOTECH1vICAL, INC. 504 -A05.9 December 23, 2011 Page 12 in levels of groundwater, springs, and/or perched water may occur due to variations in precipitation, temperature, and other factors. Faulting and Regional Seismicity The site is situated in an area of active and potentially active faults, as is most of metropolitan southern California. Active faults present a variety of potential risks to structures, the most common of which are strong ground shaking, dynamic densification, liquefaction, mass wasting, and surface rupture at the fault plane. Generally speaking, the following four (4) factors are the principal determinants of seismic risk at a given location: • Distance to seismogenically capable faults. • The maximum or "characteristic" magnitude earthquake for a capable fault. • Seismic recurrence interval, in turn related to tectonic slip rates. • Nature of earth materials underlying the site. Surface rupture represents the primary potential hazard to structures built in an active fault zone. Review of official maps delineating State of California earthquake fault zones found that the subject site is located in the northwestern portion of the Valerie Quadrangle. No Alquist - Priolo fault study zones are located within this quadrangle. In addition, the site is not located within a zone of mandatory study for active faulting per the Riverside County Land Information System website (www3.tlma.co. riverside .ca.us /pa/rclis /index.html). Reviews of other geology maps of the La Quinta region revealed no known faults that cross or trend towards the subject site. HILLTOP GEOTECH1vICAL, INC. 504 -A05.9 December 23, 2011 Page 13 The San Andreas fault (Coachella Segment) is located approximately 13.2 kilometers to the northeast of the of the subject site. To the southwest and west - southwest, the San Jacinto fault (Anza and Coyote Creek Segments) pass within approximately 27.4 and 30.0 kilometers, respectively, of the subject site. The Burnt Mountain fault is located within approximately 39.7 kilometers of the site. Accordingly, the potential for surface fault rupture on this site is considered to be very low. Ground shaking is judged to be the primary hazard most likely to affect the site, based upon proximity to four (4) regionally significant active faults as listed in the following table. Other significant fault zones, including several zones in the high desert area, are located at distances exceeding 40 kilometers from the site. Greater distances, lower slip rates, and lesser maximum magnitudes indicate much lower risk to the site from the latter fault zones than the four (4) closest faults. Characteristics of the major active fault zones selected for inclusion in analysis of strong ground shaking are listed in the following table: HILLTOP GEOTECHNICAL, INC. Distance Fault Slip Reference Fault Zone' from Site Length Rate Earthquake Fault Type (km)2 (km)' (mm/yr)' M(M.), San Andreas (Coachella Segment) 13.2- 96±10 25.0±5.0 7.2 A (rl -ss)3 San Jacinto (Anna Segment) 27.4 91±9 12.0±6.0 7.2 A (rl -ss) San Jacinto (Coyote Creek Segment) 30.0 41 ±4 4.0±2.0 6.8 A (rt -ss) Burnt Mtn. 39.7 21±2 0.6±0.4 6.5 B (rl -ss) HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 14 Distance Fault Slip Reference Fault Fault Zone' from Site Length Rate Earthquake 1 (km)2 (km)' (mm/yr)l W .)' Type 1. California Department of Conservation, Division of Mines and Geology, 1996 (Appendix A - Revised 2002), Probabilistic Seismic Hazard Assessment for the State of California, DMG Open -File Report 96 -08. 2. Blake, Thomas F., 2000, Preliminary Fault -Data for EQFault, EQSearch and FrishSP and Blake, Thomas, F., Computer Services and Software, Users Manuals, FriskSP v. 4.00, EQSearch v. 3.00, and EQFault v. 3.00. 3. Fault Geometry: (ss) strike slip; @ reverse; (n) normal; (rl) right lateral; (11) left lateral; (0) oblique; (45 N) direction. . Probabilistic seismic hazard maps and data files prepared by the California Geological Survey (CGS) determine ground motions "'with a 10- percent probability of being exceeded in the next 50 years (475 years mean return time) as a fraction of the acceleration due to gravity for peak ground acceleration (Pga) and spectral accelerations (Sa) for short and moderately long periods, 0.2 seconds and 1.0 second, respectively. This data was available at the CGS `Probabilistic Seismic Hazards Mapping Ground Motion Page' ( http: / /www.conservation.ca.gov/ cgs /rghm /pshamap /pshamain.asp). The probabilistic hazard maps were calculated for alluvial sites (Site Class D) such as the subject property. The values are presented in the following table for reference: GROUND SITE ACCELERATION Site Class D MOTION (Alluvium) * Pga 0.492g Sa @ 0.2 Sec. 1.1768 Sa @ 1.0 Sec. 0.651g a` 10- percent probability of being exceeded in the next 50 years (475 years mean return time). HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 15 The web site indicates that NEHRP soil corrections were used to calculate the values for alluvium (Site Class D). Ground motion values were interpolated from a 0.05 degree spacing grid of calculated values. Interpolated ground motion may not equal the values calculated for a specific site, therefore the values are not intended for design or analysis. Probabilistic seismic hazard maps and data files prepared by the U.S. Geological Survey (USGS) assign a 2- percent likelihood that a Peak Horizontal Ground Acceleration (pga) of approximately 0.7438 will occur at this site within the next 50 years,:.(2,475 years mean return time) due to a Model Magnitude earth quake of 7.76 located at a distance of approximately 13.3 km from the subject site. This data was available at the USGS `Probabilistic Seismic Hazard Deaggregation Program' website ( http: // eqint. cr. usgs .gov /deaggint/2002 /index.php). Actual shaking intensities at the site from any seismic source may be substantially higher or lower than estimated for a given earthquake magnitude, due to complex and unpredictable effects from variables such as: • Near- source directivity effects. • Direction, length, and mechanism of fault rupture (strike -slip, normal, reverse). • Depth and consistency of unconsolidated sediments. • Topography. • Geologic structure underlying the site. • Seismic wave reflection, refraction, and interference. HILLTOP GEOTECBNICAL, INC. 504 -A05.9 December 23, 2011 Page 16 Secondary Seismic Hazards Secondary hazards include induced landsliding or mass wasting, liquefaction, flooding (from ruptured tanks and reservoirs, surface oscillations in larger lakes, or seismic sea waves), and subsidence as a result of soil densification. Landsliding and liquefaction susceptibility maps have been prepared for much of coastal Los Angeles and Orange County, California by the CGS. However, this area of Riverside County, California is not presently scheduled for mapping by the State. As of the date of this report, the site has not been identified or excluded from a State - delineated zone of mandatory study for either landsliding or liquefaction. Landslide: The subject site is not located within a designated area as having a landslide susceptibility per Riverside County Land Information System website (www3.tlma.co. riverside .ca.us /pa/rclis /index.html). Due to the flat -lying nature of the site, on -site landsliding or debris flows sourced from higher elevations should not be considered to be a geologic constraint at this site. Liquefaction: The subject site is located within a designated area as having a `High' liquefaction potential per Riverside County Land Information System website (www3.tlma.co. riverside .ca.us /pa/rchs /index.html). Liquefaction is a phenomenon where a sudden large decrease of shearing resistance takes place in fine grained cohesionless and/or low plasticity cohesive soils due to the cyclic stresses produced by earthquakes causing a sudden, but temporary, increase of porewater pressure. The increased porewater pressure occurs below the water table, but can cause propagation of groundwater upwards into overlying soil and possibly to the ground surface and cause sand boils as HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 17 excess porewater escapes to the surface when groundwater is shallow. Potential hazards due to liquefaction include significant total and/or differential settlements of the ground surface and structures as well as potential collapse of structures due to loss of support of foundations. Laboratory testing and soil condition analyses, at sites where liquefaction has occurred, have shown that the soil types most susceptible to liquefaction are saturated, fine sand to sandy silt. These soils derive their shear strength from intergranular friction and do not drain quickly during earthquakes. Published studies and field and laboratory test data indicate that coarse sands, gravelly sands, and silty or clayey sands are considerably less vulnerable to liquefactions To a large extent, the relative density of sands also controls the liquefaction susceptibility for a given number of cycles and acceleration levels during a seismic event. Other characteristics such as confining pressure and the stresses created within the soil during a seismic event also affect the liquefaction potential of a site. Liquefaction of soil does not generally occur below depths of 40 to 50 feet below the ground surface due to confining pressure at that depth. Moreover, saturated fine sands with relative densities of approximately 70 percent or greater are not likely to liquefy, even under very severe seismic events. Liquefaction Program: A formal liquefaction analysis was performed as part of this geotechnical / geologic study update using the LiquefyPro, Version 5.5h, Copyright 2008, CivilTech Software, computer program. This program is based on the most recent publications of the NCEER Workshop and SP117 Implementation. The liquefaction potential of the alluvium identified in the exploratory excavations performed for the Reference No. 8 ` Geotechnical Study' noted on the second page of the cover letter for this report was evaluated in general accordance with procedures proposed in published references (Seed and Idriss, 1971: Tokimatsu, 1987; Youd and Idriss, 1997). HILLTOP GEOTECBNICAL, INC. 504 -A05.9 December 23, 2011 Page 18 Input Parameters: Faulting and Regional Seismicity: The "Faulting and Regional Seismicity" section of this report addressees the major fault systems and ground motion parameters which would effect the subject site. An earthquake of model magnitude 7.76 based on a 2- percent probability of exceedance in 50 years - 2,475 year Mean Return Time per the USGS `Probabilistic Seismic Hazard Deaggregation Program' website ( http: // eqint. cr. usgs .gov /deaggint/2002 /index.php) and a calculated peak ground acceleration (pga) of 0.600g based on the Spectral Response Acceleration (Sr obtained from the Java Ground Motion Parameter Calculator - Version 5.0.9a available at USGS web site (http: / /earthquake.usgs. gov /research/hazmaps /design/) divided by 2.5 per Section 11.8.3 of ASCE /SEI 7 -05 were used in the liquefaction evaluation. Groundwater: A groundwater depth of 24 feet below the existing ground surface at the time the field study was performed for the Reference No. 8 `Geotechnical Study' noted on the second page of the cover letter for this report and an assumed historic groundwater depth of 5.0 feet below the existing ground surface at the subject site were used in the evaluation. Grain Size: Laboratory tests to determine the quantity of soil passing the #200 sieve were performed on samples obtained from the field study which was performed for the referenced `Geotechnical Study.' The test results are presented on the `Summary of Laboratory Test Results,' Plate No. 11, presented in Appendix `A.' Blow Counts: Standard Penetration Tests (SPT) were performed during the field study which was performed for the referenced `Geotechnical Study.' Field blow counts are presented on the `Subsurface Exploration Log' for boring B -4, Plate Nos. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 19 6a through 6c, presented in Appendix `A.' The field SPT blow counts were corrected for sampler type, effective overburden, energy ratio, rod length, and the blow counts were adjusted to a "standardized" penetration resistance values - (N) so for use in the liquefaction analysis. Relative Density: The relative density of the subsurface materials was determined based on the SPT blow counts and the in -situ moisture content and dry density test results performed on relatively undisturbed samples obtained during the field study which was performed for the referenced `Geotechnical Study.' The moist and saturated unit weights of soils used in the liquefaction analysis were interpreted from tables in the NAVFAC Design Manual 7.01, September 1986. Liquefaction Analyses: Soil strata above the groundwater depth of 24 feet and the assumed highest groundwater table elevation of 5.0 feet below ground surface were not included in the liquefaction analysis. The Cyclic Stress Ratio to cause liquefaction for a magnitude 7.5 earthquake was calculated and modified for an earthquake of magnitude 7.76. The earthquake induced Cyclic Stress Ratio (CSR) was calculated and the factor of safety determined for the various earth strata. Results and Conclusions: A Factor of Safety against the occurrence of liquefaction greater than 1.3 is considered to be an acceptable level of risk for non - liquefiable materials for the evaluation based- on the guidelines presented in California Department of Conservation, Division of Mines and Geology, 2008, Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117A. The results of the liquefaction analysis are shown on Plate Nos. C -1 and C -2, `Liquefaction Analysis,' presented in Appendix `C.' HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 20 The results of the evaluation indicate that approximately 27 and 42 feet of material underlying the subject site under a groundwater depth of 24 feet and an assumed high groundwater depth of 5.0 feet below the ground surface, respectively, have a liquefiable potential (Factor of Safety of less than 1.3) under the peak ground acceleration of 0.600g and maximum earthquake magnitude of 7.76. Total liquefaction settlements of 5.49 and 8.18 inches, respectively, were estimated based on the liquefaction analysis under the peak ground acceleration, the maximum earthquake condition, and the groundwater depth of 24 feet and 5.0 feet below the ground surface. The differential settlements due to liquefaction are expected to be approximately one -half of the total settlements because of the presence of deep alluvial sediments and uniformity of soil layers on the subject site. The removals and recompaction to depths of 4.0 to 7.0 feet of the surface soils on the subject site which were performed during the previous grading on the site will also reduce the amount of settlement which could occur at the surface as a result of liquefaction. Due to the liquefaction potential of the subject site and the potential for differential settlement of as much as 2.7 to 4.1 inches, foundations for the proposed structures should be stiffened and designed to consider the liquefaction potential and prevent catastrophic collapse due to the loss of foundation support that might result due to liquefaction of the site during the design earthquake event. At a minimum, the stiffening of the foundation system should be based upon criteria limited to fulfilling life safety concepts. Additionally, using the above criteria, the foundations should be designed by the "Structural Engineer" in accordance with the current codes at the time of construction. HILLTOP GEOTECBNICAL, INC. 504 -A05.9 December 23, 2011 Page 21 If total elimination of the risk of ground distress due to potential liquefaction of the site is needed, and/or if the elimination of the potential for liquefaction to occur at the site are desired, additional site exploration, laboratory testing, and engineering analysis would be needed. Alternate foundation system recommendations such as driven pile, cast -in- drilled -hole (CIDH) pile foundations and/or site remediation procedures such as wick drains, grouting, sand or stone columns, or other such methods could also be needed for the project. Seismically Induced Subsidence: Loose sandy soils subjected to moderate to strong ground shaking can experience settlement. Experience from the Northridge Earthquake indicates that structural distress can result from such seismic settlement. Where applicable, loose, near - surface, alluvial soils and undocumented fills should be removed and recompacted to uniform high densities to mitigate both settlement and consolidation potentials. The subject site is located within an area designated as having a `High' subsidence susceptibility per Riverside County Land Information System website (www3.tlma.co.riverside.ca.us/pa/rclis/index.html). A formal dry sand settlement analysis was performed using the LiquefyPro computer program. This program is based on the most recent publications of the NCEER Workshop and SP117 Implementation. An estimated additional. settlement of approximately 4.4 inches was calculated for the upper 24 feet of the alluvium underlying the subject site under intense seismic shaking based on an earthquake of magnitude 7.76 and a probabilistic peak ground acceleration (pga) of 0.6008. The results of the analysis are presented on Plate No. C -3, `Dry Sand Settlement Analysis,' presented in Appendix `C.' HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 22 Lateral Spreading: Lateral spread is the most pervasive type of liquefaction - induced ground failure. Lateral spreads can occur on gently sloping ground or where nearby drainage or stream channels can lead to static shear stress biases on essentially horizontal ground. During lateral spread, blocks of mostly intact, surficial earth material displace downslope or towards a free face along a shear zone that has formed within the liquefied sediment. The resulting ground deformation typically has extensional fissures or a graben at the head of the failure, shear deformations along the side margins, and compression or buckling of the earth material at the toe. The amount of lateral displacement typically ranges from a few centimeters to several meters and can cause considerable damage to engineered structures and lifelines. A formal lateral spread analysis was not performed as part of this study. The lateral spread potential of the subject site is not considered to be a geologic hazard for the proposed single family residential structures on the subject property due to the flat lying nature of the subject site. Seiching: Seiching involves an enclosed body of water oscillating due to ground shaking, usually following an earthquake. Lakes and water towers are - typical bodies of water affected by seiching. However, the site does not appear to be within the influence of large bodies of water and, as such, seiching should not be considered a geologic hazard for the development of the subject site. Tsunamis: Because of the inland geographic location of the site, tsunamis are not considered a geologic hazard for the development of the subject site. Lurching: Lurching is a phenomena in which ground cracking and/or secondary faulting occurs as a result of ground shaking. Generally, lurching primarily occurs HILLTOP GEOTECM'41CAL, INC. 504 -A05.9 December 23, 2011 Page '23 in the immediate vicinity of faulting or within typical building setback zones or "No Human Occupancy" zones. No evidence of faulting was encountered on the site and the likelihood for lurching to impact the site is considered to be low. OTHER GEOLOGIC HAZARDS Flooding The subject site is not located within a designated area as having a flooding potential per Riverside County Land Information System website (www3.tlma.co.riverside.ca.us/pa/rclis/l*ndex.html). Flood Insurance Rate Maps (FIRM) were compiled by the Federal Emergency Management Agency (FEMA) for the Flood Insurance Program and are available for most areas within the United States at the FEMA web site (http: / /mse.fema.gov /). The attached `FEMA Flood Hazard Map' and `FEMA Flood. Hazard Map Legend,' Figure Nos. 3a and 3b, respectively, are based on FIRMs provided by FEMA and is specific to the area around the subject site. The FEMA Flood Hazard Map' indicates that the site is not located within a 100 -year flood zone. Therefore, flooding is not considered to be a constraint for the development of the subject project at this location. GENERAL The conclusions and recommendations presented in this report are preliminary since a grading plan, the type of structure construction, structural loads, finish floor elevations, etc. were not available and are, in part, based on the review of the Reference Nos. 1,2,3,4, and 8 reports noted on the cover letter of this report for the HILLTOP GEOTECHNICAL, INC. 62ND AVENI s 0 1000 2000 Scale Approximate in Feet Reference: U.S. Federal Emergency Management Administration (FEMA), Effective August 28, 2008, Flood Insurance Rate Map, Map No. 06065C2925G G Panel 2925 of 3805. Site Specific Information Obtained Through FEMA Website, Map Service Center (http: / /mse.fema.gov/). FEMA FLOOD HAZARD MAP By: AH Date: 12/11 HILLTOP GEATMHNIGAL -Coll6B41e6 Project No.: 504 -A05.9 Figure No.: 3a LEGEND SPECIAL FLOOD HAZARD AREAS SUBJECT TO INUNDATION .BY THE 1% ANNUAL CHANCE FLOOD The 1% annual flood (100 -year flood), also known as the base flood, is the flood that has a.1% chance of being equaled or exceeded in any given year. The Special Flood Hazard Area is the area subject to flooding by the 1% annual chance flood. Areas of Special Flood Hazard include Zones A, AE, AH, A0, AR, A99, V, and VE. The Base Flood Elevation is the water- surface elevation of the 1% annual chance flood. ZONE A No Base Flood Elevations. determined. ZONE AE Base Flood Elevations determined. ZONE AH Flood depths of 1 to 3 feet (usually areas of ponding); 'Base Flood Elevations determined. ZONE AO Flood depths of 1 to 3 feet (usually sheet flow on sloping terrain); average depths_ determined. For areas of alluvial fan flooding, velocities also determined. ZONE AR Special Flood Hazard Area formerly protected from the 1% annual chance flood by a flood control system that was subsequently decertified. Zone AR indicates that the former flood control system is being restored to provide protection from the 1% annual chance or greater flood. r ZONE A99 Area to be protected from 1% annual chance flood by :a Federal flood protection system under construction; no Base Flood Elevations determined. ZONE .V Coastal flood zone with velocity hazard .(wave action); no Base Flood Elevations determined. ZONE VE Coastal flood zone with velocity hazard (wave 'action); Base Flood Elevations determined. OTHER AREAS ZONE X Areas determined to be outside the 0.2% annual chance floodplain. ZONED Areas in which'flood hazards are undetermined, but possible. FEMA FLOOD HAZARD MAP LEGEND A IA& By: AH Date: 12/11 HILLTOp GEOTECHNICAL Project No.: 504 -AO5.9 Figure'No.: 3b FLOODWAY AREAS .IN .ZONE AE The floodway is the.channel of a stream plus any adjacent floodplain areas that must be kept free of encroachment so that the 1% annual chance flood can be carried without substantial increases in flood heights. OTHER FLOOD AREAS ZONE X Areas of 0.2% annual .chance.flood; areas of 1% annual chance flood with average depths of less than 1 foot or with drainage areas less than 1 square mile; and areas protected by levees from 1% annual chance flood. OTHER AREAS ZONE X Areas determined to be outside the 0.2% annual chance floodplain. ZONED Areas in which'flood hazards are undetermined, but possible. FEMA FLOOD HAZARD MAP LEGEND A IA& By: AH Date: 12/11 HILLTOp GEOTECHNICAL Project No.: 504 -AO5.9 Figure'No.: 3b 504 -A05.9 December 23, 2011 Page 24 subject site, information provided to this firm, the results of the field and laboratory data obtained from six (6) exploratory excavations located on the subject property for the Reference No. 8 ` Geotechnical Study' noted on the second page of the cover letter for this report, experience gained from work conducted by this firm on projects within the general vicinity of the subject site, the project description and assumptions presented in the `Project Description / Proposed Development' section of this report, engineering analyses, and professional judgement. Based on a review of the field and laboratory data and the engineering analysis, the proposed development is feasible from a geotechnical / geologic standpoint. The subject property�can be developed without adverse impact onto or from adjoining properties providing the recommendations contained within this report are adhered to during project design and construction. The field observations indicate that up to 4.0 to 7.0 feet of material present on the subject site was a previously, documented, fill material (See Reference No. 1, `Report of Grading,' noted on the first page of the cover letter for this report). The previously documented, man -made fills on the subject site are considered suitable for the support of structural fills, fill slopes, foundations, slab -on -grade floor slabs, hardscape, and/or pavement. Field observations and laboratory tests suggest that the alluvial materials on the site are subject to liquefaction during the design seismic event anticipated for the area. The near - surface fill and alluvial soils present on the subject site exhibit an expansion potential in accordance with the criteria presented in Section 1803.5.3, `Expansive Soil,' in the 2010 California Building Code (CBC). If precautions are not taken during the design and construction of the project, the on -site expansive HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 25 earth materials could cause heaving and distress to the structures, hardscape, and pavement if they should become saturated in the future. Depending on the uniformity of the depth and the area of saturation, the uplift may not be uniform throughout the structure and/or fill area. Therefore, special design considerations such as a `Slab -on- Ground Foundation' system, `Post- Tension Slab -on- Ground' foundation system, deepened footings and/or pre - saturation of earth materials under hardscape are required due to expansion potential of the near - surface, on- site soils. Some reconditioning of the upper 12 inches of the existing, documented fill on the site in areas where no cut or fill is proposed or where structural fills, structures, exterior hardscapes, and/or pavement are proposed will have to be performed due to the length of time since completion of grading and the effects of weathering. The actual conditions of the near - surface supporting material across the site may vary. The nature and extent of variations of the surface and subsurface conditions may not become evident until construction. If variations of the material become evident during construction of the proposed development, HGI should be notified so that the project Geotechnical / Geologic Consultant can reevaluate the characteristics of the material and the conclusions and recommendations of this report, and, if needed, make revisions to the conclusions and recommendations presented herein. Recommendations for site grading, foundations, slab support, pavement design, slope maintenance, etc., are presented in the subsequent paragraphs. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 26 SITE PREPARATION RECOMMENDATIONS General The grading recommendations presented in this report are intended for: 1) the rework of unsuitable, near - surface, fill and alluvial earth materials to create engineered building pads and satisfactory support for exterior hardscape (i.e., sidewalks, patios, etc.) and pavement; and 2) the use of a deepened, conventional, shallow foundation system, a `Slab -on- Ground Foundation' system, a `Post- Tension Slab -on- Ground' foundation system, and concrete hardscape cast on -grade designed to resist the expansion potential of the near - surface on -site earth materials. .r° r Some reconditioning of the upper 12 inches of the existing documented fill on the site in areas where no cut or fill is proposed will have to be performed due to the length of time since completion of grading and the effects of weathering. If hardscape and pavement subgrade earth materials are prepared at the time of grading of the building pads, and the improvements are not constructed immediately, additional observations and testing of the subgrade earth material will have to be performed to locate areas which may have been damaged by construction traffic, construction activities, and/or seasonal wetting and drying. The additional observations and testing should be performed before placing aggregate base material, Hot Mix Asphalt (HMA) concrete, and/or Portland Cement concrete (PCC) in those areas. The following recommendations may need to be modified and/or supplemented during grading as field conditions dictate. The grading should be performed in accordance with the recommendations presented in this report. We recommend that HGI, as the Geotechnical Engineer / Geologist of Record, be retained by the owner of the proposed project to observe HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 27 the excavation and grading operations, foundation preparation, and test the compacted fill and utility trench backfill. A pregrading conference should be held at the site with representatives of the owner, the grading contractor, the City of La Quinta, the Civil Engineer, and a representative of HGI in attendance. Special grading procedures and/or concerns can be addressed at that time. Earthwork observation services allow the testing of only a small percentage of the fill placed at the site. Contractual arrangements with the grading contractor by the project owner should contain the provision that he is responsible for excavating, placing, and compacting fill in accordance with the recommendations presented in this report and the approved project grading plans and specifications. Observation by the project Geotechnical / Geologic Consultant and/or his representatives during grading should not relieve the grading contractor of his responsibility to perform the work in accordance with the recommendations presented in this report and the approved project plans and specifications. The following recommendations may need to be modified and/or supplemented during grading as field conditions require. Final Grading Plan Review The project Civil Engineer should review this report, incorporate critical information on to the grading plan and/or reference this geotechnical / geologic study, by Company Name, Project No., Report No., and report date, on the grading plan. Final grading plans should be reviewed by HGI when they become available to address the suitability of our grading recommendations with respect to the proposed improvements. HILLTOP GEOTECH14ICAL, INC. 504 -A05.9 December 23, 2011 . Page 28 Clearing and Grubbing Debris, grasses, weeds, brush, and other deleterious materials should be removed from the proposed building, exterior hardscape and pavement areas and areas to receive structural fill before grading is performed. Any organic material and miscellaneous /demolition debris should be legally disposed of off site. Any topsoil or highly organic soils encountered should be stripped and stockpiled for use on finished grades in landscape areas or exported from the site. Disking or mixing of organic material into the earth materials proposed to be used as structural fill should not be permitted. Trees, bushes, etc. and their roots should be completely removed, ensuring that 95 percent or more of the root systems are extracted. Man -made objects encountered (i.e., irrigation systems, underground utilities, construction debris, etc.) should be overexcavated, exported from the site, and legally disposed of off site. Excavation Characteristics Excavation and trenching within the subject property to the depths anticipated for the proposed development is anticipated to be relatively easy in the near - surface fills and alluvial materials on the subject site and should be accomplished with conventional earth - moving equipment. Materials are not anticipated at shallow depths that would require heavy ripping or blasting to excavate. It is not anticipated that a significant amount of oversized rock material (i.e., 12 inches in greatest dimension) will be generated during the removal and replacement process within the existing documented fill and near - surface alluvial materials which will require special handling during the development of the site. HILLTOP GEOTECIINICAL, INC. 504 -A05.9 December 23, 2011 Page 29 Suitability of On -Site Materials as Fill In general, the on -site earth materials are considered satisfactory for reuse as fill. Fill materials should be free of significant amounts of organic materials and/or debris and should not contain rocks or clumps greater than 12 inches in maximum dimension. It is noted that the average in -situ moisture content of the near - surface documented fill and near - surface alluvial earth materials on the subject site is anticipated to be below the optimum moisture content for the on -site materials and that moisture will have to be added to the on -site earth materials if the earth materials are to be used as compacted fill material in the near future. No significant amount of oversized rock�materials are anticipated to be generated from the cuts performed in the local materials. Removal and Recompaction Uncontrolled or undocumented fills and/or unsuitable, loose, or disturbed near - surface alluvial earth material in proposed areas which will support structural fills, structures (i.e., buildings, decorative block walls, retaining walls, trash enclosure walls, etc.), fill slopes, exterior hardscape (i.e., sidewalks, patios, curb / gutters, etc.), and pavement should be prepared in accordance with the following recommendations for grading in such areas. If overexcavation of any undocumented fill or loose, near - surface alluvial soils in areas that were not previously graded is elected not to be performed in hardscape, curb / gutter, pavement, and decorative block wall or fence areas, penetration of irrigation water with time may cause some settlement and distress to the improvements in those areas. The cost of the additional grading verses the risk of distress and cost of repairs to the structures needs to be evaluated by the project owner. • Any near - surface undocumented fill and/or near - surface alluvial earth materials on the site that were not previously graded are recommended to be overexcavated and recompacted. Based on the exploratory borings and HILLTOP GEOTECB ICAL, INC. 504 -A05.9 December 23, 2011 Page 30 laboratory test results performed for the Reference No. 8 `Geotechnical Study' noted on the second page of the cover letter for this report and the previous grading performed on the subject site (See Reference No. 1, `Report of Grading,' noted on the first page of the cover letter for this report), it is anticipated that the overexcavation will extend to a depth of approximately 4.0 to 7.0 feet below the original ground surface in the alluvial areas which will receive structural fill, building structures, retaining walls, trash enclosure walls, and decorative concrete block walls. In areas on the subject site where proposed fills will be placed and documented, properly, compacted fills had been placed, the near surface • soils on the subject site need only be scarified to a depth of 6.0 to 12 inches, brought to optimum moisture content to 3.0 percent above optimum moisture content, and compacted to 90 percent or greater relative compaction before placement of fill. A relative compaction of 85 percent or greater should be obtained in the exposed earth material at the overexcavation depth prior to performing any scarification, moisture conditioning, and recompaction. If 85 percent relative compaction is not present, the overexcavation should be deepened • until a minimum of 85 percent relative compaction is present. Moreover, the depth of the overexcavation within the perimeter of the proposed structures should be to a uniform elevation throughout the limits of the structures. It is noted that fill placed to construct slopes and/or support • sidewalks, patios, retaining walls, block walls, driveways, and pavement are considered to be structural fill. • Where a cut / fill transition zone or a compacted fill / alluvial transition. extends through a proposed building pad area, a compacted mat of fill will have to be constructed under the building area to prevent differential settlement between the two (2) dissimilar materials. This mat should be constructed by overexcavating the materials in the cut portion of the pad to a distance outside the proposed building limits of 5.0 feet or to the depth of • the overexcavation below the finish pad grade, whichever is greater. The overexcavation should extend to a depth of 4.0 feet below the pad elevation, to a depth of 2.0 times the width of the largest footing below the bottom of the proposed deepest footing, .or to a minimum depth of 0.5 times the depth • of the deepest fill within the building pad, whichever is greater. In a total cut building pad in previously compacted and documented fill, no additional over excavation and recompaction is required if 4.0 feet or more �. HILLTOP GEOTECBMCAL, INC.. 504- A'05.9 December -23, 2011 Page 31 of documented fill remains below the finish pad grade. In total cut building pads for the proposed structures where less than 4.0 feet of documented fill will remain, overexcavation and recompaction is recommended to be performed to a depth of 4.0 feet below the proposed cut pad elevation: This will provide a uniformly compacted building pad for support ofthe structure. • In the proposed exterior hardscape (i.e., sidewalks, patio slabs, etc.), and pavement areas where structural fill will not be placed or cuts are proposed, the existing near - surface earth materials need only be processed to a depth of 12 inches below existing site grades or proposed subgrade elevation, whichever is deeper unless old, undocumented fill materials are encountered at exposed grades. If undocumented fills are encountered, they will need to be overexcavated and properly compacted fill replaced to achieve proposed grades. -t�4 • Additional overexcavation will need to be performed in areas where the exposed subgrade can not be properly processed and recompacted per the following recommendations presented in this section of this report. If wet, unstable earth material is encountered at the overexcavation depth, additional overexcavation and a 1.5 to 2.5 inch gravel worked into the earth material may be required to establish a firm working base for the placement of fill. As an alternative, a mud coat (i.e., sand /cement slurry) consisting of a minimum of 2.0 sacks of cement per cubic yard of sand may be placed over the soft subgrade and allowed to cure overnight. This will establish a firm working base for the placement of fill. • The limits of overexcavation for the building pads should extend to a distance of 5.0 feet or to the depth of the overexcavation beneath the finish pad grade for the structure, whichever is greater, beyond the structure perimeter or footing edges or beyond the front, side, and rear building setback limits on the lots. The limits of overexcavation for fill slopes should extend to a distance of 4.0 feet beyond the toe of the slope or to the depth of the overexcavation beneath the toe of the slope, whichever is greater. The limits of overexcavation for the decorative concrete block perimeter wall footings and/or retaining wall footings should extend to a distance of 4.0 feet beyond the footing edges or to the depth of the overexcavation beneath the footing grade, whichever is greater. The limits of processing or overexcavation for exterior hardscape, curb / gutter, and pavement areas should extend to a distance of 2.0 feet beyond the edge of the exterior HILLTOP- GEOTECHNICAL, INC. r 504 -A05.9 December 23, 2011 Page 32 hardscape, curb / gutter, or pavement, or to the depth of the overexcavation beneath the finish subgrade elevation, whichever is greater. In areas where overexcavation can not be performed to the required distance beyond the foundations, (i.e., perimeter project block walls, retaining walls, etc.) along property lines, the foundations should be deepened to extend through the loose, near - surface earth materials and be founded to a minimum depth of 1.0 foot into the firm underlying material. • It is noted that localized areas, once exposed, may warrant additional overexcavation for the removal of existing undocumented fills, soft or loose, near - surface alluvial earth materials, and subsurface obstructions and/or debris which may not have been located during the grading previously performed on the subject site. Actual depths of removals and the competency of the exposed overexcavation bottoms should be determined by the project Geotechnical / Geologic Consultant and/or his representative during grading operations at the time they. are exposed and before scarification and recompaction or the placement of fill. • The exposed overexcavation bottom surfaces should be scarified to a depth of 6.0 to 12 inches, brought to optimum moisture content to 3.0 percent above optimum moisture content, and compacted to 90 percent or greater relative compaction before placement of fill. Maximum.dry density and optimum moisture content for compacted materials should be determined according to current ASTM D1557 procedures. The scarification and recompaction of the exposed overexcavation bottoms in the previously placed and documented fill materials may be deleted upon approval by the project Geotechnical / Geologic Consultant, and/or his representative when in -place density test results in the undisturbed materials indicate a relative compaction of 90 percent or greater and a moisture content equal to slightly above optimum moisture content for the materials being tested. Import Material Import fill should be `Non- Expansive' as defined in Section 1803.5.3, `Expansive Soil,' in the 2010 CBC (i.e., Expansion Index _< 20) as determined by current ASTM D4829 procedures and have strength parameters equivalent to or greater than the on -site earth materials.. Import fill material should be approved by the project Geotechnical / Geologic Consultant prior to it being brought on -site. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 33 Fill Placement Requirements Fill material, whether on -site material or import, should be approved by the project Geotechnical / Geologic Consultant and/or his representative before placement. Fill material should be free from vegetation, organic material, debris, and oversize material (i.e., 12 inches in maximum dimension). Approved fill material should be placed in horizontal lifts not exceeding 6.0 to 12 inches in compacted thickness or in thicknesses the grading contractor can demonstrate that he can achieve adequate compaction and watered or aerated to obtain optimum moisture content to 3.0 percent above optimum moisture content. Each lift should be spread evenly and should be thoroughly mixed to ensure uniformity ofrearth material moisture. Fill soils should be compacted to 90 percent or greater relative compaction. Maximum dry density and optimum moisture content for compacted materials should be determined in accordance with current ASTM D1557 procedures. Compaction Equipment It is anticipated that the compaction equipment to be used for the project will include a combination of rubber- tired, track - mounted, sheepsfoot, and/or vibratory rollers to achieve compaction. Compaction by rubber -tired or track - mounted equipment, by itself, may not be sufficient. Adequate water trucks, water pulls, and/or other appropriate equipment should be available to provide sufficient moisture and dust control. The actual selection of equipment and compaction procedures are the responsibility of the contractor performing the work and should be such that uniform compaction of the fill is achieved. Shrinkage, Bulking, and Subsidence There will be a material loss due to the clearing and grubbing operations. The following values are exclusive of losses due to clearing, grubbing, or the removal HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 34 of other subsurface features and may very due to differing conditions within the project boundaries and the limitations of this study. Volumetric shrinkage of the near - surface earth materials (i.e., documented fill and near - surface alluvium) on the subject site that are excavated and replaced as controlled, compacted fill should be anticipated. It is estimated that the average shrinkage of the near - surface earth materials within the upper 4.0 to 7.0 feet of the site which will be removed and replaced will be approximately 0.0 to 5.0 percent, based on fill volumes when compacted to 90 to 95 percent of maximum dry density for4he earth material type based on current ASTM D1557 procedures. For example, a 5.0 percent shrinkage factor would mean that it would take 1.05 cubic yards of excavated material to make 1.0 cubic yard of compacted fill at 95 percent relative compaction. A higher relative compaction would mean a larger shrinkage value. A subsidence factor (loss of elevation due to compaction of existing documented fill and/or the near - surface alluvial earth materials in- place) of 0.00 to 0.05 foot per foot of compacted earth material should be used in areas where the existing earth materials are compacted in -place to 90 to 95 percent relative compaction and to a depth of 12 inches. Subsidence of the site due to settlement from the placement of less than 5.0 feet of fill (not including the depth of overexcavation and replacement) during the planned grading operation is expected to be minimal. Although the above values are only approximate, they represent the recommended estimate of some of the respective factors to be used to calculate lost volume that will occur during grading. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 35 Abandonment of Existing Underground Lines Abandonment of existing underground irrigation, utility, or pipelines, if present within the zone of construction, should be performed by either excavating the lines and filling in the excavations with documented, properly compacted fill or by filling the lines with a low strength sand / aggregate / cement slurry mixture. Filled lines should not be permitted closer than 3.0 feet below the bottom of proposed footings and/or concrete slabs on- grade. The lines should be cut off at a distance of 5.0 feet or greater from the area of construction. The ends of the lines should be plugged with 5.0 feet or more of concrete exhibiting minimal shrinkage characteristics to prevent water or fluid migration into or from the lines. Capping of the lines may also be needed if the lines are subject to line pressures. The slurry should consist of a fluid, workable mixture of sand, aggregate, cement, and water. Plugs should be placed at the ends of the line prior to filling with the slurry mixture. Cement should be Portland cement conforming to current ASTM C150 specifications. Water used for the slurry mixture should be free of oil, salts, and other impurities which would have an adverse effect on the quality of the slurry. Aggregate, if used in the slurry, mixture should meet the following gradation or a suitable equivalent: SIEVE SIZE PERCENT PASSING 1.5" 100 1.0" 80 -100 3/4" 60 -100 3/8" 50 -100 No.4 40 -80 No. 100 10 -40 HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 36 The sand, aggregate, cement, and water should be proportioned either by weight or by volume. Each cubic yard of slurry should not contain less than 188 pounds (2.0 sacks) of cement. Water content should be sufficient to produce a fluid, workable mix that will flow and can be pumped without segregation of the aggregate while being placed. The slurry should be placed within 1.0 hour of mixing. The contractor should take precautions so that voids within the line to be abandoned are completely filled with slurry. Local ordinances relative to abandonment of underground irrigation, utility, or pipelines, if more restrictive, supersede the above recommendations. Fill Slopes Finish fill slopes should not be inclined steeper than 2H:1V (Horizontal to' Vertical). Fill. slope surfaces should be. compacted to 90 percent relative compaction to the face of the finished slope. Overexcavation beneath proposed fill slopes should be performed in accordance with the recommendations presented in previous sections of this report. Fill slopes should be constructed in a skillful manner so that they are positioned at the design orientations and slope ratio. Achieving a uniform slope surface by subsequent thin wedge filling should be avoided. Add -on correction to a fill slope should be conducted under the observation and recommendations of the project . Geotechnical / Geologic Consultant. The proposed add -on correction procedures should be submitted in writing by the contractor before commencement of corrective grading and reviewed by the project Geotechnical / Geologic Consultant. Compacted fill slopes should be backrolled with appropriate equipment for the type of earth material being used during fill placement at intervals not exceeding 4.0 feet in vertical height. As an alternative to the bankrolling of the fill slopes, over - filling of the slopes will be considered acceptable and preferred. The fill slope should be constructed by HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 37 over - filling with compacted fill to a distance of 3.0 feet or greater horizontally, and then trimmed back to expose the dense inner core of the slope surface. Fill slopes steeper than 3H: IV are moderately susceptible to erosion due to the low cohesion parameters of the earth materials. Cut Slopes Finish cut slopes in alluvium [and/or bedrock] should not be inclined steeper than 2H:1V (Horizontal to Vertical). The cut slopes should be observed by the project Geotechnical / Geologic Consultant and/or his representative during grading to provide supplemental recommendations for stability of slopes, if needed. Cut slopes that face in the same direction as the prevailing natural slope will require top of cut paved interceptor swales. Cut slopes steeper than 3H: IV are moderately susceptible to erosion due to the low.cohesion parameters of the earth materials. Fill- Over -Cut Slopes Generally, fill- over -cut slopes should be eliminated by overexcavating the cut portion of the slope a minimum of 15 feet. The transition between cut and fill, on the slope, should be maintained as steep as possible. Loose Material on Slope Face The grading contractor should be made aware to take care to avoid spillage of loose material down the face of slopes during grading and during drainage terrace and downdrain construction. Fine grading operations for benches and downdrains should not deposit loose trimmed earth materials on the finished slope surfaces. Slope Creep Proposed slopes are planned to be stable under normal conditions and moderate earthquakes. However, movement due to creep effects of improvements located HILLTOP GEOTECWgICAL, INC. 504 -A05.9 December 23, 2011 Page 38 near the tops of proposed or existing fill and cut slopes must be considered. Due to moisture variations and natural gravity forces, the earth materials on the face of a slope tend to move downward and outward with time. Past experience has indicated that there is a zone which ranges back from the top of the slope edge that may experience movement. This zone varies from approximately 5.0 feet to 15 to 20 feet depending on the type of earth material the slope is composed of, the height of the slope, the inclination of the slope, moisture conditions, etc. The movement tends to be greatest at the top of the slope near the slope edge. Improvements within the creep zone. should be designed and constructed to accommodate the anticipated movements. The movements may very from a fraction of-an inch to several inches and is dependent'on the slope height, earth material type, distance from the slope edge, and other factors. Slope Protection Permanent slope maintenance and protection measures as presented in the subsequent `Slope Maintenance and Protection Recommendations' section of this report should be initiated as soon as practicable after completion of cut and/or fill slope construction. Fill slopes and cut slopes in undocumented fill, documented fill, and alluvial materials steeper than 3H: 1V (Horizontal to Vertical) are moderately susceptible to erosion due to the low cohesion parameters of the earth materials. The plant mix, method of application, and maintenance requirements are subject to the approval of a registered Landscape Architect or other qualified landscape professional. Construction delays; climate or weather conditions, and plant growth rates may be such that additional short -term non -plant erosion management measures may be needed. Examples would include matting, netting, plastic sheets, deep staking (5.0 feet or deeper), etc. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 39 Protection of Work During the grading process and prior to the completion of construction of permanent drainage controls, it is the responsibility of the grading contractor to provide good drainage and prevent ponding of water and damage to the in progress or finished work on the site and/or to adjoining properties. Observation and Testing During grading, observation and testing should be conducted by the project Geotechnical / Geologic Consultant and/or his representatives to verify that the grading is being performed according to the recommendations presented in this report. The project Geotechnical / Geologic Consultant and/or his representative should observe and test the overexcavation bottoms and the placement of fill and should take tests to verify the moisture content, density, uniformity and degree of compaction obtained. The contractor should notify the project Geotechnical / Geologic Consultant when cleanout and/or overexcavation bottoms are ready for observation and prior to scarification and recompaction. Typically, one (1) in -place density test should be performed for every 2.0 vertical feet of fill material, or one (1) test for every 500 cubic yards of fill, which ever requires the greater number of tests. In -place density and moisture content tests should be performed during the placement of the fill materials during the grading operations in general accordance with the following current ASTM test procedures: Standard Test Method for In -Place Density and Water Content of Soil and Soil- Aggregate by Nuclear Methods (Shallow Depth) - ASTM D6938. Test Method for Density and Unit Weight of Soil in Place by Sand Cone Method - ASTM D1556. ' Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock - ASTM D2216. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 40 Method for Determination of Water (Moisture) Content of Soil by Direct Heating Method - ASTM D4959. Method for Determination of Water (Moisture) Content of Soil by the Microwave Oven Method - ASTM D4643. Where testing demonstrates insufficient density, additional compaction effort, with the adjustment of the moisture content when needed, should be applied until retesting shows that satisfactory relative compaction has been obtained. The results of observations and testing services should be ,presented in a formal `Grading Report' following completion of the grading operations. Grading operations undertaken at the site without the project Geotechnical / Geologic Consultant and/or his representative present may result in exclusions of the affected areas from the grading report for the project. The presence of the project Geotechnical / Geologic Consultant and/or his representative will be for the purpose of providing observations and field testing and will not include supervision or directing of the actual work of the contractor or the contractor's employees or agents. Neither the presence and/or the non - presence of the project Geotechnical / Geologic Consultant and/or his field representative nor the field observations and testing will excuse the contractor for defects discovered in the contractor's work. If HGI does not perform the observation and testing of the earthwork for the project and is replaced as Geotechnical / Geologic Consultant of record for the project, the work on the project should be stopped until the replacement Geotechnical / Geologic Consultant has reviewed the previous reports and work performed for the project, agreed in writing to accept the recommendations and prior work performed by HGI for the subject project, or has performed their own studies .and submitted their revised recommendations. ,,. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 41 Earth Material Expansion Potential The preliminary expansion potential of the on -site earth materials is discussed in the subsequent foundation and floor slab recommendation sections of this report. Upon completion of grading for the building pad areas, near - surface samples should be obtained for expansion potential testing to verify, the preliminary expansion test results and the foundation / slab -on -grade recommendations presented in this report. Earth Material Corrosion Potential The preliminary corrosion potential of the on -site earth material is discussed in the subsequent corrosion recommendation sections of this report. Upon completion of grading for the building pad areas, near - surface samples should be obtained for corrosion potential testing to verify the preliminary chemical test results and the recommendations presented in this report for protection of concrete and bare metal which will be in direct contact with the on -site earth materials. 2010 CBC SEISMIC DESIGN CRITERIA Per the California Building Standards Commission, 2010 California Building Code (CBC), California Code of Regulations, Title 24, Part 2, Volume 2 of 2, Section 1613, `Earthquake Loads,' the followings coefficients and factors relevant to seismic mitigation and design for new construction include: • Site Class Types Categorizing the upper 30 meters ( ±100 ft.) of earth materials into one (1) of the site class types A, B, C, D, E, and F that are based on average shear wave velocities, Standard Penetration Test blow counts, or undrained shear strength. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 42 • Mapped, Maximum Considered Earthquake (MSC), 5.0 Percent Damped, Spectral Response Acceleration Parameters at Short Period and at 1- Second Period Mapped, Maximum Considered Earthquake (MSC), 5.0 percent damped, spectral response acceleration parameters at short period (0.2 second) and at 1- second, SS and S1 for Site Class `B' are determined from Java Ground Motion Parameter Calculator - Version 5.0.9a available at the USGS web site (http: // earthquake. usgs .gov /research/hazmaps /design/). • Site Coefficients Short period-site coefficient (at 0.2 second period), Fa and long - period site coefficient (at 1.0 second period), Fv are based on `Site Class' and the `Mapped Spectral Response Acceleration at Short Period and at 1- Second period' S8 and S1. Based on our understanding of local geologic conditions and limited in -situ penetration tests performed for the Reference No. 8 `Geotechnical Study' noted on the second page of the cover letter for this report, the `Site Class' judged applicable to this site is `D', with a `Soil Profile Name' of `Stiff Soil Profile' per Table 1613.5.2, `Site Class Definitions,' in the 2010 CBC with an average Shear Wave Velocity of 600*to 1,200 feet /second (ft. /s) or an average Standard Penetration Test value of 15 to 50 blows per foot of penetration in the upper 100 feet (30.48 m) of the site. The following table presents supplemental coefficients and factors relevant to seismic mitigation and design for new construction built according to the 2010 CBC based on a 2- percent probability of being exceeded in the next 50 years (2,475 years mean return time). HILLTOP GEOTECHNICAL, INC. 4 504 -A05.9 December 23, 2011 Page 43 SEISWHC DESIGN CRITERIA Site Location Latitude: 33.6092° North Longitude: 116.2312° West Site Class' D Mapped, Maximum Considered Earthquake (MCE), 5.0 Percent Damped, Spectral Response Acceleration Parameter at Short 1.500 Period (SX (0.2 Second) for Site Class B. Mapped, Maximum Considered Earthquake (MCE), 5.0 Percent Damped, Spectral Response Acceleration Parameter at 1- 0.600 Second (SJ)2 for Site Class B. Site Coefficients (F e)2 for Site Class. 1.0 Site Coefficients (F )2 for Site Class. 1.5 The MSC, 5.0 Percent Damped, Spectral Response Acceleration Parameter at Short Periods Adjusted for Site Class Effects 1.500 (SMS)2• The MSC, 5.0 Percent Damped, Spectral Response Acceleration 0.900 Parameter at 1- Second Adjusted for Site Class Effects (SM,)2 Design, 5.0 Percent Damped, Spectral Response Acceleration 1.000 Parameter at Short Periods (SDS)2 for Site Class. Design, 5.0 Percent Damped, Spectral Response Acceleration 0.600 Parameter at 1- Second (SDI)2 for Site Class. Model Magnitude Earthquake (M)s 7.76 Peak Ground Acceleration (Pga)9 0.7438 1. California Building Standards Commission, 2007, California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of 2, Table 1613.5.2, `Site Class Definitions.' 2. Java Ground Motion Parameter Calculator - Version 5.0.9a available at USGS web site (htt-p://earthquake.usas.gov/research/hazmai)s/desiuo. 3. Probabilistic seismic hazard maps and data files prepared by the U.S. Geological Survey (USGS) assign a 2- percent likelihood that the Pga will occur at this site within the next 50 years (2,475 years mean return time). This data was available at the USGS `Probabilistic Seismic Hazard Deaggregation Program' website ( http:// egint. cr. usgs .gov /deaggint/2002 /index.php). HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 44 Actual shaking intensities at the site from any seismic source may be substantially. higher or lower than estimated for a given earthquake magnitude, due to complex and unpredictable effects from variables such as: • Near- source directivity effects. • Direction, length, and mechanism of fault rupture (strike -slip, normal, reverse). • Depth and consistency of unconsolidated sediments. • Topography. jj,: • Geologic structure underlying the site. • Seismic wave reflection, refraction, and interference. FOUNDATION DESIGN RECOMMENDATIONS General The recommendations - presented in the:.subsequent paragraphs for foundation design and coiistructio i:`are based'oii geotechnical characteristics and expansive earth material conditions for the supporting earth materials as defined in Section 1803.5.3, `Expansive Soil,' in the 2010 CBC and should not preclude more restrictive structural requirements. Per Section 1808.6, `Design for Expansive Soils,' in the 2010 CBC, foundations for structures resting on earth materials with an Expansion Index greater than 20 require special design considerations or such other engineering design based on geotechnical recommendations as approved by the building official. Foundations for proposed residential structures shouldconsist of a `Slab -on- Ground Foundation' system based on the current Wire Reinforcement Institute, Inc. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 45 procedures or a `Post- Tension Slab -on- Ground' system based on the current Post Tensioning Institute. The foundations for proposed - decorative block walls, retaining walls, etc. may consist of conventional continuous footings which are deepened to a depth below where volume changes occur in the earth materials due to wetting and drying or be isolated from the expansive earth materials. The Structural Engineer for the project should determine the actual foundation type and footing width, depth, and reinforcing to resist design vertical, horizontal, and uplift forces under static and seismic conditions. Reinforcement recommendations presented in this report are considered the minimum for the earth material conditions present on the site and are not intended to supersede the design of the 2 project Structural Engineer or the criteria of the governing agencies for the project. Deepened Conventional Foundations for Retaining Walls an Decorative Perimeter Block Walls Foundation Size: Continuous footings should have a width of 12 inches or greater. Continuous footings should be continuously reinforced with a minimum of one (1) No. 4 steel reinforcing bar located near the top and one (1) No. 4 steel reinforcing bar located near the bottom of the footings to minimize the effects of slight differential movements which may occur due to minor variations in the engineering characteristics or seasonal moisture change in the supporting earth materials. Column footings should have a width of 18 inches by 18 inches or greater and be suitably reinforced, based on structural requirements. Depth of Embedment: Footings should extend to a depth of 24 inches or greater below lowest adjacent finish grade. Frost is not considered a design factor for foundations in the City of La Quinta, California, since there will not be any significant frost penetration in the winter months. HILLTOP GEOTEMITICAL, INC. 504 -A05.9 December 23, 2011 Page 46 Footing Setback: Embedment of footings on or near existing or planned slopes should be determined by a setback distance measured from the bottom outside edge of the footing to the slope face in accordance with Section 1808.7, `Foundations on or Adjacent to Slopes,' in the 2010 CBC or the current City of La Quinta, California codes and ordinances, whichever is greater. Fine grained earth materials overlying existing and/or proposed slopes on the subject site are prone to downslope creep. The rate of creep is a function of the length and steepness of the slope, the moisture content of the earth materials, the depth of creep prone earth materials, and degree and care and maintenance of the slope. Slope creep is activated by wetting of the earth material mantle. In addition, the presence of burrowing animals can reduce the integrity of the earth materials and increase the downslope creep. Bearing Capacity: Provided the recommendations for site earthwork and for footing width and depth of embedment are incorporated into the project design and construction, the allowable bearing value for design of continuous and column footings for the total dead plus frequently - applied live loads is 1,500 pounds per square foot (psf) for footings that are 12 inches in width and a minimum depth of embedment of 24 inches below lowest adjacent finish grade in accordance with Table 1806.2, `Presumptive Load Bearing Values,' in the 2010 CBC for footings founded in undisturbed, documented, properly, compacted fill or undisturbed, firm alluvial soils (Class 5 Material). For eccentrically loaded footings and/or overturning moments, the resultant force should be in the middle one -third of the footing and the average bearing value across the footing should not exceed the recommended allowable bearing value. The allowable bearing value has a factor of safety of 3.0 or greater and may be increased by 33.3 percent for short durations of live and/or dynamic loading such as wind or seismic forces. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 47 Settlement: Footings designed according to the recommended bearing value for continuous and column footings and founded in undisturbed, documented, properly, compacted fill or undisturbed, firm alluvial soils (Class 5 Material) are not expected to exceed a total settlement of 1.0 inch or a differential settlement of 0.25 inch between similarly sized and loaded footings. `Slab -on- Ground Foundation' System A `Slab -on- Ground Foundation' system based on the current Wire Reinforcement Institute, Inc. procedures appears to be an economical system to mitigate the on- site expansive earth material conditions. Geotechnical parameters for the design of a `Slab -on- Ground Foundation' system are presented in the subsequent section. Based on `Weighted Plasticity Index' of 6.0, an assumed unconfined compressive strength (q„) of 0.8 kip per square foot (ksf), an `Effective Plasticity Index' of 6.0 for the expansive earth materials in the upper 15 feet of the on -site earth material deposits, and a `Climatic Rating (Cw) of 15 for southern California, a `Soil /Climatic Scaling Factor' (1 -C) of 0.0 is recommended for use in the design of the `Slab -On- Ground Foundation' system for the proposed structures. Other design criteria should be in accordance with the current Wire Reinforcement Institute, Inc. procedures. A `Slab -on- Ground Foundation' system designed according to the current Wire Reinforcement Institute, Inc. procedures is not expected to exceed a total settlement of 0.5 inch due to structural loads. Due to the liquefaction potential of the subject site and the potential for differential settlement of as much as 2.7 to 4.9 inches, a `Slab -on- Ground Foundation' system for the proposed residential structures should be stiffened and HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 48 designed to prevent catastrophic collapse of the structures due to the loss of foundation support that might result from differential settlement due to the potential for liquefaction of the site to occur during the design earthquake event. At a minimum, the stiffening of the foundation system should be based upon criteria limited to fulfilling life safety concepts. Additionally, using the above criteria, the foundation system should be designed by the "Structural Engineer" in accordance with the current codes at the time of construction. `Post- Tensioned Slab -on- Ground' System A `Post- Tensioned*Slab -on- Ground' system also appears &-ibe a suitable system to mitigate the on -site expansive earth material conditions for the support of the proposed residential structures. Geotechnical parameters for the design of a `Post- Tensioned Slab -on- Ground' system based on the current Post Tensioning Institute procedures (`Design of Post - Tensioned Slabs -on- Ground,' the Third Edition, Copyright 2004 with Addendum 1 dated May 2007, Addendum 2 dated May 2008, and the VOLFLO.1.5 computer program) are presented as follows: POST - TENSIONING INSTITUTE DESIGN CRITERIA Shrink Swell Calculation Calculation Center Edge Edge Moisture Variation Distance - em (Distance measured inward from slab edge in which soil 9.00 ft. 4.70 ft. moisture content varies) Value for Center Lift Swell Condition (Shrinkage), - ym sn.;nk -0.08 m. -- Value for Edge Lift Swell Condition (Swelling), - ym Swell -- +0.43 in. Allowable Bearing Valuei`, psf F 1,500 Per Table 1806.2, `Presumptive Load- Bearing Values,' for a Class 5 Material (CL, ML, MH, and CH) in the 2010 California Building Code (CBC). The allowable bearing value has a factor of safety of 3.0 or greater and may be increased by 33.3 percent for short durations of live and/or dynamic loading such as wind or seismic forces. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 49 The depth of the perimeter stiffening beams (h) is a design calculation and needs to be determined by the Structural Engineer designing the Post - Tension slab. This in turn will determine the depth of embedment below the finish pad grade which will also be a function of the designed top of slab elevation from finish pad grade. A `Post- Tensioned Slab -on- Ground' system designed according to the recommended bearing value is not expected to exceed a total settlement of 0.5 inch due to structural loads. In determining the above recommended design parameters, the following assumptions were made based on the laboratory test results presented in the Reference No. 1 `Report of Grading' and the Reference No.8 ` Geotechnical Study' noted in the cover letter for this geotechnical update report and past experience in the vicinity of the site: • Amount of fines in soil material (_50.075 mm dia.), percent = 76 • Amount of clay in soil material ( :50.002 mm dia.), percent = 10 • Liquid Limit = 29 • Plastic Limit = 23 • Depth to Constant Suction, ft. = 9.0 • Constant Suction, pF = 4.1 • Dryest Suction, pF = 4.5 (typical high value to be used for normal design conditions per the PTI Addendum No. 1 to the 3rd Edition of the design of `Post- Tensioned Slabs -on Ground'). • Wettest Suction, pF = 2.9 (typical low value of a properly drained site per the PTI Addendum No. 1 to the 3rd Edition of the design of `Post - Tensioned Slabs -on Ground'). HILLTOP GEOTECBNICAL, INC. 504 -A05.9 December 23, 2011 Page 50 • Thornthwaite Moisture Index, I. _ -20 • Gamma 100, yp = 0.01 (assumed as typical model for `Non - Expansive' soils per the PTI Addendum No. 1 to the 3rd Edition of the design of `Post- Tensioned Slabs -on Ground') • Soil Fabric Factor, Ff = 1.0 (per Table 3. 1, `Soil Fabric Factor,' in the PTI Addendum No. 2 to the 3rd Edition of the design of `Post - Tensioned Slabs -on Ground' for Non CH soils) • Vertical Barrier Depth = 0.0 ft. • Horizontal Barrier Length = 0.0 ft. • Ko Drying = 0.33 • Ko Wetting = 0.67 M Due to the liquefaction potential of the subject site and the potential for differential settlement of as much as 2.7 to 4.9 inches, a `Post- Tensioned Slab -on- Ground' system for the proposed residential structures should be stiffened and designed to prevent catastrophic collapse of the structures due to the loss of foundation support that might result from the differential settlement due to the potential for liquefaction of the site to occur during the design earthquake event. At a minimum, the stiffening of the foundation system should be based upon criteria limited to fulfilling life safety concepts. Additionally, using the above criteria, the foundations should be designed by the "Structural Engineer" in accordance with the current codes at the time of construction. Lateral Capacity Resistance to lateral loads can be provided by a combination of friction acting at the base of the foundation and passive earth pressure on the sides of the foundation system. Foundation design parameters, based on undisturbed, HILLTOP GEOTECHNIICAL, INC. 504 -A05.9 December 23, 2011 Page 51 documented, properly compacted fill (Class 5 Material) and/or undisturbed, firm alluvial soils (Class 5 Material) for resistance to static lateral dead forces are as follows: Allowable Lateral Bearing Pressure (Equivalent Fluid Pressure), Passive Case: Undisturbed, Documented, Compacted, `Expansive' Fill* - 100 pcf,* Undisturbed, Firm, On -Site, `Expansive,' Alluvial Soil* -.100 pcf Per Table 1806.2, `Presumptive Load - Bearing Value,' for a Class 5 Material (Cl, ML, MH, and CH) in the 2010 California Building Code (CBC). ** Pounds per square foot per foot of depth (pcf). Allowable Lateral Sliding Resistance Between Soil and Concrete: Undisturbed, Documented, Compacted, `Expansive' Fill* - 130 psf Undisturbed, Firm, On -Site, `Expansive,' Alluvial Soil* - 130 psf Per Table 1806.2, `Presumptive Load - Bearing Values,' for a Class 5 Material (CL, ML, MH, and CH) in the 2010 California Building Code (CBC) to be multiplied by the contact area as limited in Section 1806.3.2, `Lateral Sliding Resistance Limit,' in the CBC. The above values are allowable design values and have safety factors of 2.0 or greater incorporated into them and may be used in combination without reduction in evaluating the resistance to lateral loads. The recommended lateral resistance assumes a horizontal surface for the earth material mass extending to a distance of 10 feet or greater from the face of the foundation system, or three (3) times the height of the surface generating passive pressure, whichever is greater. The allowable values may be increased by 33.3 percent for short durations of live and/or dynamic loading, such as wind or seismic forces. For the calculation of the allowable lateral bearing pressure (passive earth resistance), the upper 1.0 foot of material should be neglected unless confined by a concrete slab or pavement. The largest recommended allowable lateral bearing pressure (passive earth resistance) HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 52 is 15 times the recommended design value for the appropriate CBC class of material. The lateral sliding resistance value is to be multiplied by the contact area but should not exceed one -half the dead load for the foundation system. Interim Foundation Plan Review It is recommended that HGI review the foundation plans for the structures as they become available. The, purpose of this review is to determine:if these.plans have been prepared in accordance with..the recommendations contained in this report. This review-- will also • provide us an . opportunity ' to submit additional recommendations as conditions warrant. T Final Foundation Design Recommendations Final foundation recommendations should be made upon completion of grading and be included in the `Report of Grading' prepared by the Geotechnical / Geologic Consultant for the project. Foundation Excavations Foundation excavations should be observed by the project Geotechnical / Geologic Consultant and/or his representative prior to placement of forms, reinforcing steel, or placement of concrete for the purpose of verification of the recommendations presented in this report and for compliance with the project plans and specifications. The foundation excavations should be trimmed neat, level, and square. Any loose or sloughed material and debris should be removed from the foundation excavations prior to placement of reinforcing steel and removed again prior to the placement of concrete. Earth materials removed from the foundation excavations should not be placed in slab -on- grade, hardscape, and/or pavement areas unless compacted to 90 percent or greater relative compaction. The R HILLTOP GEOTECH1vICAL, INC. 504 -A05.9 December 23, 2011 -Page 53 maximum dry density and optimum moisture content for the earth material should be determined in accordance with current ASTM D1557 procedures. SLAB -ON -GRADE FLOOR RECOMMENDATIONS The recommendations for concrete slabs on- grade, both interior and exterior, excluding Portland Cement Concrete (PCC) pavement, are based on geotechnical characteristics and `Expansive' conditions for the supporting earth material as defined in Section 1803.5.3, `Expansive Soil,' in the 2010 CBC and a moderate to high liquefaction potential for the subject site. The expansion potential of the slab subgrade areas should be verified at the completion of grading of the building pad areas. Concrete slabs should be designed to minimize cracking as a result of shrinkage. Joints (isolation, contraction, and construction) should be placed in accordance with the current American Concrete Institute (ACI) or Portland Cement Association (PCA) guidelines. Special precautions should be taken during placement and curing of concrete slabs. Excessive slump (high water / cement ratio) of the concrete and/or improper curing procedures used during either hot or cold weather conditions could result in excessive shrinkage, cracking, or curling in the slabs. It is recommended that concrete proportioning, placement, and curing be performed in accordance with ACI recommendations and procedures. Due to the liquefaction potential of the subject site and the potential for differential settlement of as much as 2.7 to 4.9 inches, a `Slab -on- Ground Foundation' system or a `Post- Tensioned Slab -on- Ground' system for the proposed residential structures should be stiffened and designed to prevent catastrophic collapse of the structures due to the loss of foundation support that might result from differential settlement due to the potential for liquefaction of the site to occur during the design earthquake event. At a minimum, the stiffening of the foundation system should be based upon criteria limited to fulfilling life safety HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 54 concepts. Additionally, using the above criteria, the foundation system should be designed by the "Structural Engineer" in accordance with the current codes at the time of construction. `Slab -on- Ground Foundation' System The recommendations presented in the previous foundation design section for .a `Slab -on- Ground Foundation' system includes the interior floor slab design criteria. for the structures. A compacted: sand or gravel bedding layer beneath lightly loaded floor slabs is not needed but may be desirable to enhance the design section for heavy floor loads. If gravel bedding is used, it should consist of a well graded, crushed aggregate. The sand or gravel layer should be compacted to 90 percent or greater of maximum dry density, as determined by current ASTM D1557 procedures.. If a vapor barrier / moisture retarder is used under the floor slab and it is placed on well graded, crushed, gravel material, it is recommended that a 1.0 inch thick layer of sand or other approved granular material be placed beneath the vapor barrier / moisture retarder to prevent punctures from angular gravel fragments and projections. If open graded gravel (capillary break) is placed beneath the vapor barrier or retarder, the gravel should be a 6.0 inches or greater in thickness. If open graded gravel is used, a separation. fabric such as Mirafi 140N series or an equivalent substitute should be used in -leu of a sand cushion to protect the vapor barrier / moisture retarder from punctures. Subgrade earth materials should be moisture conditioned to optimum moisture content to 3.0 percent above optimum moisture content to a depth of 12 inches and proof compacted to 90 percent or greater relative compaction based on current ,� ;.. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 55 ASTM D1557 procedures immediately before placing the gravel material, the moisture barrier, or pouring concrete. `Post- Tensioned Slab -on- Ground' System The recommendations presented in the previous foundation design section for a `Post- Tensioned Slab -on- Ground' foundation' system includes the interior floor slab design criteria for the structures. A compacted sand or gravel bedding layer beneath lightly loaded floor slabs is not needed but may be desirable to enhance the design section for heavy floor loads: If gravel bedding is used, it should consist of a well graded, crushed aggregate. The sand or gravel layer should be compacted to 90 percent or greater of maximum dry density, as determined by current ASTM D1557 procedures. If a vapor barrier / moisture retarder is used under the floor slab and it is placed on well graded, crushed, gravel material, it is recommended that a 1.0 inch thick layer of sand or other approved granular material be placed beneath the vapor barrier / moisture retarder to prevent punctures from angular gravel fragments and projections. If open graded gravel (capillary break) is placed beneath the vapor barrier or retarder, the gravel should be a 6.0 inches or greater in thickness. If open graded gravel is used, a separation fabric such as Mirafi 140N series or an equivalent substitute should be used in -leu of a sand cushion to protect the vapor barrier / moisture retarder from punctures. Subgrade earth materials should be moisture conditioned to optimum moisture content to 3.0 percent above optimum moisture content to a depth of 12 inches and proof compacted to 90 percent or greater relative compaction based on current HILLTOP GEOTECBNICAL, INC... • • • w • • • • w w • • • • w • • • • • • • w • • • w • w • • w 504 -A05.9 December 23, 2011 Page 56 ASTM D1557 procedures immediately before placing the gravel material, the moisture barrier, or pouring concrete. Vapor Barrier / Moisture Retarder Recommendations HGI does not practice in the field of moisture vapor transmission evaluation / mitigation. Therefore,. it is ' recommended that. a qualified person or firm be engaged or consulted with to. evaluate the general and specific moisture vapor transmission paths and any impact on the proposed construction. This person or firm should.provide recommendations for mitigation of potential adverse impact of moisture vapor transmission on various components of the structure as deemed appropriate in accordance with ACI, PCA, ASTM, PTI, the California Building Code, and/or the International Residential Code. In heated / air conditioned areas in a structure where moisture sensitive floor coverings are anticipated over the floor slab, the use of a vapor barrier / moisture retarder beneath the slab should be considered. Typically, a vapor retarder is not utilized under the floor slabs in garages, utility buildings, and other unheated accessory structures, driveways, walks, patios, and/or other flatwork not likely to be enclosed and heated at a later date. The use or non -use of a vapor barrier / moisture retarder, the thickness of the vapor barrier / moisture retarder, the use of a granular layer over the vapor barrier / moisture retarder, the thickness of the granular materials, the type of granular material, etc. should be determined by the Structural Engineer who is designing the floor slab in conjunction with the Architect who is specifying the use and the type of floor coverings to be placed over the floor slab, and/or a person or firm that practices in the field of moisture vapor transmission evaluation / mitigation. The vapor barrier t moisture retarder recommendations provided by the supplier of the flooring materials should also be incorporated into the project plans. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 57 EXTERIOR CONCRETE FLATWORK Exterior concrete slabs cast on finish subgrade (i.e., pedestrian walkways, patios, sidewalks, etc., with the exception of PCC pavement) should be 4.0 inches or greater in thickness and be underlain by 12 inches or greater of earth material that has been prepared in accordance with the `Earthwork Recommendation' section of this report. Reinforcing in the slab, the design compressive strength of the concrete, and the use of a compacted sand or gravel base beneath the slabs should be according to the current codes and ordinances of the City of La Quinta, California. Subgrade earth materials should be moisture conditioned to optimum moisture content to 3.0 percent above optimum moisture content to a depth of 12 inches or greater and proof compacted to 90 percent or greater relative compaction based on current ASTM D1557 procedures immediately before placing aggregate base material, placing reinforcing steel, or placing the concrete. Due to the expansion potential of some of the near - surface on -site earth materials, exterior slabs -on -grade will experience seasonal vertical movement and cracking. There are several alternatives for minimizing or mitigating the impacts of expansive earth materials beneath exterior flatwork. Recommendations to reduce the distress to concrete flatwork include moisture conditioning the subgrade earth materials, using Won-Expansive' fill, and providing adequate construction and control joints in the concrete. It should be noted that localized cracking, vertical movement, and distress could still occur. • The minimum recommendations for concrete flatwork constructed on expansive earth materials is to properly prepare the clayey earth materials prior to placing concrete. This is typically achieved by scarifying, moisture conditioning, and re- compacting the subgrade earth material. The subgrade earth materials should be moisture conditioned to a depth of 18 to 24 inches or greater and to 3.0 percent or greater of the optimum moisture content for the supporting earth materials as determined by current ASTM D1557 HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 58 0 procedures. The subgrade earth materials should be compacted using moderate compaction effort to a relative compaction of 87 to 92 percent relative compaction. If the near- surface subgrade earth materials had previously been compacted, and tested, the subgrade earth materials could possibly be moisture conditioned by gradually wetting the earth material, depending on the time of the year the flatwork construction occurs. This procedure should not include flooding or. excessively wetting-.of the earth material, which would likely result in soft, unstable subgrade conditions, and possible delays in the construction while waiting for the earth materials to dry out. In general, the subgrade earth materials should be firm and non- , yielding prior to constructing the flatwork. • The replacement of `Expansive' earth materials with `Non - Expansive' earth materials, aggregate base, crushed rock, gravel, sand, etc,. in localized areas under exterior flatwork should be avoided unless the materials are provided with a positive drainage system which will prevent a "bathtub" type situation. If `Non- Expansive' earth materials, aggregate base, crushed rock, gravel, sand, etc, are used under the exterior flatwork, the materials should D be proof compacted to 90 percent or greater relative compaction based on ASTM D1557 procedures. The subgrade earth materials under the `Non- . Expansive' earth materials, aggregate base, crushed rock, gravel, sand, etc, should be prepared in accordance with the recommendations in the above 0 bulleted paragraph. • • Use of maximum control joint spacing of no more than 8.0 feet in each direction and a construction joint spacing of 10 to 12 feet should be used in the design of flatwork on expansive earth materials. Construction joints that abut the foundations or garage slab should include a felt strip, or approved equivalent, that extends the full depth of the exterior slab. This • will help to reduce the potential for permanent vertical offset between the slabs due friction between the concrete edges. It is recommended that exterior slabs be isolated from adjacent foundations. If the subgrade earth materials are allowed to become saturated, there is a risk of heaving and vertical differential movement of the exterior concrete hardscape, . sidewalks, curbs / gutters, etc. Therefore, proper drainage should be established away from such improvements and minimal precipitation or irrigation water HILLTOP GEOTECBNICAL, INC. • 504 -A05.9 December 23, 2011 Page 59 allowed to percolate into the earth materials adjacent to and/or under the exterior concrete flatwork or hardscape, curbs / gutters, etc. RETAINING WALL RECOMMENDATIONS Retaining walls may be needed to achieve finish grades for the proposed building pads, driveways, parking areas, and/or landscape areas. Retaining walls should be designed in accordance with the recommendations in the following sections. If earth reinforced walls, crib wall, keystone walls, etc. are used for the development of the subject site, the design requirement of the proprietary wall system should supercede the following recommendations if there are any conflicts. Static Lateral Earth Pressures Retaining walls backfilled with `Non - Expansive' granular soil (i.e., Expansion Index (EI) <_ 20 and Unified Soil Classifications of SP, SW, SM, GP, GW, and GM) within a zone extending upward. and away from the heel of the footing at a slope of 0.5HJV (Horizontal to Vertical) or flatter for level backfill and 03HAV for a 2H: 1V slope behind the retaining wall can be designed to resist static lateral earth pressures equivalent to those recommended in the following table: LATERAL EARTH. PRESSURE Level Backfill and Soil 2HJV Sloped Backfill and Classification* Soil Classification * ** Condition SP, SW, GM SM SP, SW, GM SM GP, GW GP, GW Active 30 pcf ** 40 pcf 45 pcf 40 62 81 At -Rest 60 pcf 60 pcf 60 pcf 87 110 120 HILLTOP GEOTECHNICAL, INC. s i r s A r 504 -A05.9 December 23, 2011 Page 60 Per Table 1610.1, `Lateral Soil Load,' in the 2010 CBC. Equivalent fluid Pressure, pounds per square foot per foot of depth (pcf). * *� Based on a moist unit weight of 125 pcf and an Angle of Internal Friction of 38 degrees for SP, SW, GP, and GW backfill soils, 31 degrees an for GM backfill soils, and 28 for an Angle of Internal Friction of 28 for SM backfill soils. The designer of the retaining wall should specify the type of backfill material to be used in the active / at -rest zone behind the retaining wall. The expansive soils encountered on the subject site should not be used as backfill for retaining walls. Retaining walls that are free to deflect 0.001 radian at the top should be designed for the above - recommended active condition. Retaining walls that are not capable it of this movement should be assumed rigid and designed for the at -rest condition. The above values assume well - drained backfill and that a buildup of hydrostatic pressure will not occur. Surcharge loads, dead and/or live (i.e., construction loads, etc.), acting on the backfill within a horizontal distance behind the retaining wall, equivalent to or less than the vertical height of the retaining wall, should also be considered in the design. Uniform surcharge pressures should be applied as an additional uniform (rectangular) pressure distribution. The lateral earth pressure coefficient for a uniform vertical surcharge load behind the retaining wall is 0.50. Seismic and wind loads should also be added to the design loads on the retaining walls, if applicable. Seismic Lateral Earth Pressure In accordance with Section 1803.5.12, `Seismic Design Categories D through F,' in the 2010 CBC, seismic loads should also be added to the design loads on the retaining walls. A simple procedure for determining the lateral force on a retaining wall due to an earthquake is to compute the initial static pressure and add to it the increase in HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 61 pressure due to ground motion. For design of cantilevered or unrestrained retaining walls with level, granular backfill resisting seismic lateral forces due to a repeatable design acceleration of 0.320g based on a peak ground acceleration (pga) of 0.492g for a 10- percent probability of being exceeded in the next 50 years (475 years mean return time), a lateral pressure distribution in the form of an inverted triangle, with an equivalent fluid pressure of 31 pcf should be applied against the retaining wall. For seismic design of restrained, non - yielding retaining walls, a lateral pressure distribution in the form of an inverted triangle, with an equivalent fluid pressure of 77.5 pcf should be used. The total lateral seismic force acts along the retaining wall length at a height of 0.6H from the base of the retaining wall where H is the height of the retaining wall. Under the combined effect of the static and seismic loads on the retaining wall, a factor of safety of 1.1 should be used. Foundation Design Retaining wall footings should be founded to the same depths below lowest adjacent finished grade and offsets from the face of slopes, and into undisturbed, observed, and tested, compacted fill, or firm, competent, undisturbed, alluvial earth material as standard foundations. The foundations may be designed for the same average allowable bearing value across the footing (as long as the resultant force is located in the middle one -third of the footing), and with the same allowable static and seismic allowable lateral bearing pressure, allowable passive earth pressure, and allowable sliding resistance as recommended in the `Foundation Design Recommendations' section of this report. Retaining walls should be designed for a factor of safety of 1.5 against lateral sliding and overturning per Section 1807.2.3, `Safety Factor,' in the 2010 CBC. HILLTOP GEOTECHIVICAL, INC. • • • 504 -A05.9 December 23, 2011 Page 62 0 Subdrain A subdrain system should be constructed behind, and at the base of retaining walls to allow drainage and to prevent the buildup of excessive hydrostatic pressures. The subdrain system should be designed by the project Civil Engineer. The use of water- stops, impermeable barriers, or other dampproofing or waterproofing methods should be considered for any retaining walls where moisture migration through the retaining wall is considered critical to the performance and/or appearance of the retaining walls. A waterproofing consultant should be retained to provide specific waterproofing recommendations for the project. Typical subdrains may include weep holes with a continuous free draining gravel gallery, perforated pipe surrounded by free draining filter rock, or another - approved system. The option of providing an ungrouted, open coarse ofblock at the �1 bottom of a retaining wall is not a recommended drainage option since the openings in this coarse are so often covered by landscape soil, hardscape, and or pavement. Gravel galleries and/or filter rock, if not designed and graded for the on -site and/or import materials, should be enclosed in a geotextile fabric such as Mirafi 140N series, or an equivalent substitute, to prevent infiltration of fine soil particles into the subdrain and clogging of the system. Before placement of the fabric, the top of the footing should be cleared of loose soil materials, large stones, 0 and/or other debris. Any large depressions or holes should be filled with a concrete slurry or a suitable equivalent to permit close contact of the fabric with the • surrounding surface. The fabric should be placed smoothly without folds or excessive wrinkles. Successive sheets of the fabric should be placed with an overlap of 24 inches or more in the direction of the flow of the water in the pipe with the upstream layer overlapping the downstream layer. The fabric should be folded over the top of the free draining granular material producing an overlap of 12 inches or more. The perforated pipes should be Schedule 40 or stronger and 4.0 HILLTOP GEOTECH114ICAL, INC. 504 -A05.9 December 23, 2011 Page 63 inches or greater in diameter. Perforations maybe either bored 0.25 -inch diameter holes or 0.1875 -inch (3/16 -inch) wide slots placed on the bottom one -third of the pipe perimeter. If the pipe is bored, a minimum of 10 holes per linear foot should be uniformly placed along the pipe. If slots are used, they should not exceed 2.0 inches in length and should not be closer than 2.0 inches on center along the length of the pipe. The total length of the slots should not be less than 50 percent of the pipe length and should be uniformly spaced along the length of the pipe. Pipe perforations should be placed downward. Gravel filters should have a volume of 3.0 cubic feet or greater per linear foot of pipe. Subdrains should maintain a positive flow gradient and have outlets that draindn a non - erosive manner. Prefabricated drainage products such as `Miradrain,' or a suitable equivalent, may also be used for the purpose of providing drainage behind retaining walls when installed in accordance with the manufacturers recommendations. Backfill Backfill directly behind retaining walls (if backfill width is less than 3.0 feet) may consist of 0.5- to 0.75 -inch diameter, rounded to subrounded gravel with less than 5.0 percent passing the 0.5 inch sieve, enclosed in a geotextile fabric such as Mirafi 140N series, or an equivalent substitute, or a clean sand (Sand Equivalent Value greater than 50) water jetted into place to obtain compaction. If water jetting is used, the subdrain system should be in place. Even if water jetting is used, the sand should be densified to 90 percent or greater relative compaction. If the specified density is not obtained by water jetting, mechanical methods will have to be used.. If other types of soil or gravel are used for backfill, mechanical compaction methods will have to be used to obtain a relative compaction of 90 percent or greater of maximum dry density. Backfill directly behind retaining walls should not be compacted by wheel, track or other rolling by heavy HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 64 construction equipment unless the retaining wall is designed for the surcharge loading. If gravel, clean sand, or other imported backfill is used behind retaining walls in unpaved areas, the upper 12 to 18 inches of backfill should consist of typical on -site material compacted to 90 percent or greater relative compaction to prevent the influx of surface run -off into the granular backfill and into the subdrain system. Maximum dry density and optimum moisture content for backfill materials should be determined according to current ASTM D1557 procedures. V -Drain Design .s. -A V -drain should be constructed directly behind retaining walls which have a sloping backfill to intercept surface water and drain it from the back of the retaining wall. The V -drain should be designed and constructed in accordance with the current typical standards of the City of La Quinta, California. The V -drain should direct water from the back of the retaining wall to an adequate down drain and discharge it in a non - erosive manner. Observation and Testing During retaining wall construction, observation and testing, should be conducted by the project Geotechnical / Geologic Consultant and/or his representatives to verify that the work is being performed according to the recommendations presented in this report. The foundation excavations should be observed by the project Geotechnical / Geologic Consultant and/or his representative prior to placement of forms, reinforcing steel, or placement of concrete for the purpose of verification of the recommendations presented in this report and for compliance with the project plans and specifications. The foundation excavations should be trimmed neat, level, and square. Any loose or sloughed material and debris should be removed . -. HILLTOP GEOTECHNICAL, INC. ,:. 504 -A05.9 December 23, 2011 Page 65 from the foundation excavations prior to placement of reinforcing steel and removed again. prior to the placement of concrete. The placement and construction of the subdrain system behind the retaining walls should be observed by the project Geotechnical / Geologic Consultant and/or his representatives to verify that the work is being performed according to the recommendations presented in this report. During backfill of the retaining walls, observation and testing should be conducted by the project- Geotechnical / Geologic Consultant and/or his representatives to verify that the backfilling is being performed according to the recommendations presented in this report. The project Geotechnical / Geologic Consultant and/or his representative should observe the placement of fill and should take tests to verify the moisture content, density, uniformity and degree of compaction obtained. Where testing demonstrates insufficient density, additional compaction effort, with the adjustment of the moisture content when needed, should be applied until retesting shows that satisfactory relative compaction has been obtained. The results of observations and testing services should be presented in a formal report following completion of the construction operations. Retaining wall backfill operations undertaken at the site without the project Geotechnical / Geologic Consultant and/or his representative present may result in exclusions of the affected areas from the final report for the project. The presence of the project Geotechnical / Geologic Consultant and/or his representative will be for the purpose of providing observations and field testing and will not include supervision or directing of the actual work of the contractor or the contractor's employees or agents. Neither the presence and/or the non - presence of the project Geotechnical / Geologic Consultant and/or his field HILLTOP GEOTECBNICAL, INC. 504 -A05.9 December 23, 2011 Page 66 representative nor the field observations and testing will excuse the contractor for defects discovered in the contractor's work. Reinforced Earth Retaining Walls If earth reinforced walls, crib walls, segmented walls, keystone walls, etc. are used for the development of the subject site, the design requirement of the proprietary retaining wall system should utilized. Preliminary values for use in design of a reinforced earth retaining wall system can be submitted upon request, if required. CORROSION POTENTIAL EVALUATION The recommendations for corrosion protection should be verified at the completion of grading of the building pads on the subject site. Tests were performed on bulk samples of the near surface, on -site earth materials obtained from the borings during the field study performed for the Reference No. 8 `Geotechnical Study,' noted on the second page of the cover letter for this report to evaluate the potential for corrosivity. Tests were also performed on the samples of earth materials tested for the maximum dry density / optimum moisture content relationship and on samples obtained from the finish pad grades for the Reference No 1 `Report of Grading' noted on the first page of the cover letter for this report to evaluate the potential for corrosivity. Results from the tests are included in the data presented in Appendix `A' of this report. Concrete Corrosion The results of the tests performed suggest a soluble sulfate concentration of 0.012 to 0.653 percent. Earth materials with a water soluble sulfate (SO,) concentration of less than 0.10, from 0.10 to 0.20, and from 0.20 to 2.0 percent are considered to be Category S, Class S0, S1, and S2, respectively, and a `Not Applicable,' `Moderate,' and `Severe' Severity, respectively, in accordance with Table 4.2.1, - HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 67 `Exposure Categories and Classes,' in the 2008 American Concrete Institute (ACI) 318 `Building Code and Commentary,' Chapter 4. Based on the results of the soluble sulfate tests performed for the finish pad grads on each lot for the referenced `Report of Grading,' approximately 45 percent of the lots had a `Not Applicable' Severity, approximately 44 percent ofthe lots had a Moderate' Severity, and approximately 11 percent of the lots had a ` Severe' Severity. It is recommended that samples be obtained from the finish pad grades at the completion of grading to further evaluate the `Severity' of the potential for concrete ;�- corrosion. The requirements in Table 4.3.1, `Requirements for Concrete by Exposure Class,' in ACI 318 -08, Chapter 4, are applicable. The referenced ACI Table 4.2.1 should be used to determine the type cement, the maximum water cement ratio, and the minium compressive strength to be used for normal weight concrete which comes in direct contact with the on -site earth materials (i.e., foundations, floor slabs, driveway slabs, sidewalks, patios, curbs / gutters, etc.). A lower water / cement ratio or higher compressive strength may be required for design of concrete for water tightness or for protection against freezing and thawing, or for corrosion protection of concrete reinforcement per Section 1904, `Durability Requirements,' in the 2010 CBC, if applicable. Experience in the southern California area has shown that even though the earth materials do not contain levels of soluble sulfate which would require the use of sulfate resistant cement, maximum water cement ratios, or minimum compressive strength for concrete, concrete corrosion and erosion problems still occur. These problems are the result of concentrations of soluble sulfate, chloride, and other salts and/or acids present in groundwater, irrigation water, rain water, and potable water sources, and in fertilizers or amendments used to promote plant growth (i.e., some domestic water sources contain levels of dissolved sulfate which would be a HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 68 `Moderate' severity (Class S 1) exposure to concrete which comes in contact with it). Therefore, it may be wise to use a concrete designed for a Category S, Class S1, with a `Moderate' Severity criteria presented in the 2008 ACI 318, Chapter 4, Table 4.3.1, `Requirements for Concrete By Exposure Class,' that comes into contact with surface run -off or other sources of water. Higher strength, lower water/ cement ratio, and denser concrete may also be effective in reducing the potential for evaporation to occur and preventing damage due to salt or acid exposure. The use of sulfate resistant concrete for non - structural elements (i.e., driveway slabs, sidewalks, patios, curbs / gutters, etc.), is considered to be a value / risk assessment and,decision to bemade by the owner / developer. Metallic Corrosion The life of buried metals depends on type of material, thickness, and construction details. Since HGI does not practice metallic corrosion engineering, if corrosion protection is considered to be a design issue, an engineer specializing in corrosion should be consulted regarding the potential damage due to corrosion. The corrosion engineer should recommend appropriate types ofpiping and/or protective measures where needed. Minimum resistivity tests were performed on samples of the near surface, on -site earth materials obtained from the borings for the field study performed for the Reference No. 8 `Geotechnical Study' noted on the second page of the cover letter for this report to evaluate the potential for corrosivity. Minimum resistivity test results of 2,938 and 5,226 ohm -cm suggest a mild to moderate corrosive environment for buried ferrous metal in direct contact with the on -site earth materials when the earth materials are wet to saturated. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 69 Soluble chloride tests were performed on samples of the near surface, on -site earth materials obtained from the borings for the field study performed for the Reference No. 8 `Geotechnical Study,' noted on the second page of the cover letter for this report. Soluble chloride tests were also performed on the samples used for the maximum dry density / optimum moisture content relationship tests and from the samples obtained from approximately 10 percent of the finish pad grades for the Reference No 1 `Report of Grading' to evaluate the potential for corrosivity. The test results suggests a soluble chloride concentration of 100 to 2,570 parts per million (ppm). Earth materials with greater than 300 and 500 ppm of soluble chloride are considered to be aggressive to buried ferrous and copper material, a� respectively, in direct contact with the earth materials. Earth material pH is a general indicator of the corrosivity of earth materials. Tests were performed on samples of the near surface, on -site earth materials obtained from the borings for the field study performed for the Reference No. 8 `Geotechnical Study,' noted on the second page of the cover letter for this report to evaluate the potential for corrosivity. The measured pH of the near - surface, on- site, earth material of 6.0 and 6.6 indicates a non - corrosive environment to copper and ferrous metals when in direct contact with the on -site earth materials. It is recommended that additional samples be obtained and tests performed during the proposed grading to further evaluate the corrosion potential of copper and ferrous metals in direct contact with the on -site soils if corrosion protection is considered to be a design issue. Salt Crystallization Exposure Damage of concrete, concrete masonry units, slump stone block, etc. surface can occur when evaporation of moisture takes place at the surface of the materials. As HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 70 evaporation takes place, salts (i.e,. carbonates, chloride, sulfur, sodium, potassium, etc.) are deposited in or form on the surfaces. As the salts crystalize, they can exert extreme pressures in the pore spaces of the materials they are deposited in and/or on. The formation of the crystals within the pore spaces of the material can result in what is generally called `salt crystallization damage.' This results in the scaling and/or etching of the surface of the material on which they are deposited. The damaging effects of this phenomenon can be greatly reduced and/or even eliminated by the following or other such methods: 1) either using a higher strength concrete or a denser, low porosity product; 2) seal the surface of the material with a water proofing substance which will prevent the evaporation of the moisture from within the cementitious product. If `salt crystallization damage' is considered to be an issue, an engineer or chemist specializing in this area should be consulted regarding the potential damage due evaporation and the deposition of salts. The engineer or chemist should recommend appropriate types of materials or protective measures where needed. SWIMMING POOL RECOM ENDATIONS Retaining walls and foundations for a swimming pool and/or spa can be designed in accordance with the recommendations previously presented in this report. A subdrain system should be constructed around and beneath the pool and spa structures to allow drainage and to prevent the buildup of excessive hydrostatic pressures and uplift if the pool and/or spa are drained. Typical subdrains may include perforated pipe surrounded by filter rock, or another approved system. Gravel galleries and/or filter rock, if not designed and graded for the on -site and/or import backfill materials, should be enclosed in a geotextile fabric such as Mirafi 140N series, or an equivalent substitute, to prevent infiltration of fine soil particles and clogging of the system. The perforated pipes should be 4.0 inches or larger in HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 71 diameter. Pipe perforations should be placed downward. Gravel filters should have a volume of 1.0 cubic feet or larger per linear foot of pipe. Subdrains should maintain a positive flow gradient and have outlets that drain in a non - erosive manner or be connected to a sump with a pump or reverse flow valves installed in the pool bottom. The walls of the pool and spa should be designed for the following conditions: • Pool full of water without earth material on the outside. • Pool empty and earth material on the outside. The approximate earth material pressures acting on the walls of the pool and spa can be determined by the recommendations presented in the retaining wall section of this report. If a new pool and/or spa are to be constructed near an existing structure, special design and construction procedures will. be needed if the foundations for the existing structure are located above a zone defined by a 1: 1 (Horizontal to Vertical) plane inclined upward toward the existing structure from the nearest edge of the pool excavation. If the existing foundations are within this zone, the foundations for the existing structure should be underpinned or deepened to a depth below the above described plane or the pool and spa walls designed for the additional surcharge loads due to the footings. The amount of the additional surcharge load will be dependent on the actual loads on the existing footings and the actual location of the existing footings with respect to the pool and spa walls. If the footings for the existing structure are HILLTOP GEOTECHNICAL, INC. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 504 -A05.9 December 23, 2011 Page 72 located within the above described zone, and are not underpinned, special construction techniques such as shoring or slot cuts, will have to be utilized to prevent loss of vertical and lateral support of the existing foundations. Recommendations for wall surcharge loads, foundation underpinning, shoring, or slot cut procedures can be presented when specific information regarding the pool location, the depth of the pool or spa, and the depth and loads on the existing structure foundations are available. If the pool and/or spa are to be constructed near the top of a slope and within the anticipated creep zone, the design of the foundations should be such that the improvement within the creep zone are supported below the anticipated creep zone. SLOPE STABILITY EVALUATION Since anticipated cut and fill slopes for the development of the site are not anticipated to exceed 10 feet in vertical height and will not be steeper than 2H:1V (Horizontal to Vertical), a formal slope stability analysis was not performed as part of this study. The proposed cut and fill slopes should be constructed at an inclination of 2H:1V or flatter. It is anticipated that the proposed cut slopes will expose the previously graded and compacted fill materials. It is anticipated that any proposed fill slopes will be constructed of the materials obtained from the proposed cuts for the development of the subject site and will be composed of the existing, documented, fill materials which are present on the subject site. It is the opinion of this firm that the proposed cut and fill slopes will be grossly and surficially stable when designed at a 2H:1V inclination or flatter. However, the compacted fill and exposed cut materials will be vulnerable to erosion if precautions as recommended in the `Slope Maintenance and Protection' section of this report are not implemented as soon as practicable after completion of grading. HILLTOP..GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 73 PRELIMINARY PAVEMENT RECOMMENDATIONS The following are preliminary recommendations for the structural pavement section for the proposed streets, parking areas, and driveway areas for the subject development. The Hot Mix Asphalt (HMA) pavement sections have been determined in general accordance with current California Department of Transportation (CALTRANS) design procedures using the Ca1FP Ver. 1.1 `Hot Mix Asphalt Empirical Design' computer program developed by the CALTRANS, ` Office of Pavement Design and are based on an assumed Traffic Index (TI) for a 20 year design life and an assumed R -Value of at least 30 based on past experience in the vicinity of the site and visual textural classification of the on -site earth materials and/or import materials which are anticipated to be at subgrade elevation. Portland Cement Concrete (PCC) pavement sections are based on equivalent structural numbers as the recommended HMA pavement section. The preliminary recommendations for the pavement sections should consist of the following: RECOMMENDED PAVEMENT SECTIONS Site Area Traffic Pavement Section Index* 3.0" Hot Mix Asphaltic Concrete (HMA) over 5.5" Aggregate Base (AB) Subdivision <5.0 or Streets 5.2" PCC @ 2,500 psi over properly prepared subgrade. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 74 RECOMMENDED PAVEMENT SECTIONS Site Area _T Pavement Section Inc 4.2" HMA over 9.0" AB Interior Collector or Streets s 7.0 7.8 PCC @ 2,500 psi over properly prepared subgrade. * Traffic Index was assumed for the project. It is noted that the City of La Quinta, California minimum pavement sections may override the above pavement recommendations without prior City review and approval. 'The pavement section for individual lot driveways should be according to current City of La Quinta, California standards. HMA concrete pavement materials should be as specified in Section 39, `Hot Mix Asphalt,' in the current CALTRANS Standard Specifications or an equivalent substitute. Aggregate base should conform to Class 2 (37.5 -mm (1 -1/2 "} Maximum or 19 -mm (3/4 ") Maximum) material as specified in Section 26- 1.02A, `Class 2 Aggregate Base,' in the current CALTRANS Standard Specifications, or an equivalent substitute. Portland Cement Concrete sections are based on a compressive strength of 2,500 psi or greater at 28 days for the concrete. Higher strength design for the concrete can permit thinner pavement sections. Lower strength design for the concrete will require thicker pavement sections. Joints (longitudinal, transverse, construction, and expansion), jointing arrangement, joint type, pavement and/or joint reinforcing, as well as drainage, crowning, finishing and curing of PCC pavement should be in accordance with current Portland Cement Association (PCA) recommendations. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 75 The subgrade earth material, including utility trench backfill, should be compacted to 90 percent or greater relative compaction to a depth of 1.0 foot or greater below finish subgrade elevation. The aggregate base material should be compacted to 95 percent or greater relative compaction. If asphaltic concrete and/or PCC pavement is placed directly on subgrade, the upper 6.0 inches of the subgrade should be compacted to 95 percent or greater relative compaction. Maximum dry density and optimum moisture content for subgrade and aggregate base materials should be determined according to current ASTM D1557 procedures. The asphalt concrete pavement should be densified to 95 percent or greater of the density obtained by current California Test 304 and 308 procedures (Hveem compacted laboratory samples). Where HMA pavement abuts concrete aprons, drives, walks, or curb and gutter sections, a thickened edge transition zone is recommended for the HMA section to minimize the effects of impact loading as vehicles transition from PCC paving to HMA paving. This thickened edge should consist of an increased thickness of 2.0 inches for parking areas and 4.0* inches for areas of heavy truck usage. This thickened edge should extend to a distance of 3.0 feet or greater from the edge of pavement and then gradually taper back to the design pavement thickness. If pavement subgrade earth materials are prepared at the time of grading of the building site and the areas are not paved immediately, additional observations and testing will have to be performed before placing aggregate base material, asphaltic concrete, or PCC .pavement to locate areas that may have been damaged by construction traffic, construction activities, and/or seasonal wetting and drying. In the proposed pavement areas, earth material samples should be obtained at the time the subgrade is graded for Resistance (R- Value) testing according to current California Test 301 procedures to verify the pavement design recommendations. HILLTOP GEOTECHNICAL, INC. w w :� -fi:. 504 -A05.9 December 23, 2011 Page 76 Because the full design thickness of the HMA concrete is frequently not placed prior to construction traffic being allowed to use the streets in a development or the parking lots, rutting and pavement failures can occur prior to project completion. To reduce this occurrence, it is recommended that either the full- design pavement section be placed prior to use by the construction traffic, or a higher Traffic Index (TI) be specified where construction traffic will use the pavement. Surface water infiltration beneath pavements could significantly reduce the pavement design life. To limit the need for additional long =term maintenance of the pavement or pre- mature failure, it would be beneficial to protect at -grade pavements from landscape water infiltration by means of a concrete cutoff wall, deepened curbs, or equivalent. Pavement cut -off barriers should be considered where pavement areas are located downslope of any landscape areas that are to be irrigated. The cut -off barrier should extend to a depth of at least 4.0 inches below the pavement section aggregate base material. Gradation is not the only quality guidelines for aggregate base material. The longevity and performance of pavements utilizing aggregate base material for support is dependent upon the quality of the material which composes the aggregate base. CALTRANS specifications do not specifically exclude the use of material other than a natural, crushed rock and rock dust for Class 2 Aggregate Base material as the Standard Specifications for Public Works Construction (2009 Edition of the `Greenbook' with the 2011 Supplement), Section 200 -2.2, does for Crushed Aggregate Base material. Often times, reclaimed Portland Cement concrete, Hot Mix Asphalt concrete, lean concrete base, and cement treated base are crushed, combined with broken. stone, crushed gravel, natural rough surfaced gravel, and sand per the current Section 26- 1.02A, `Class 2 Aggregate Base,' of the current CALTRANS `STANDARD SPECIFICATIONS,' and graded to produce a HILLTOP GEOTECHrIICAL,.INC. 504 -A05.9 December 23, 2011 Page 77 Class 2 Aggregate Base material per CALTRANS gradation specifications. Bricks, concrete masonry units, tile, glass, ceramics, porcelain, wood, plastic, metal, etc. are not an acceptable reclaimed material for use in a Class 2 Aggregate Base material per the current CALTRANS standard specifications. If a reclaimed material is proposed for use on the project as a Class 2 Aggregate Base, the reclaimed materials should not exceed 50 percent of the total volume of the aggregate used. The aggregate base material should also be tested prior to delivery to the subject project site for the following quality requirements per the current, appropriate CALTRANS procedures: TEST TEST METHOD . NO. QUALITY REQUIREMENT OPERATING RANGE CONTRACT COMPLIANCE Resistance (R- Value) Calif. Test 301 -- 78 Minimum Sand Equivalent Calif. Test 217 25 Minimum 22 Minimum Durability Index Calif. Test 229 -- 35 Minimum If a reclaimed material or a pit run aggregate is proposed for use on the project as a `Greenbook' Crushed Miscellaneous Base (CMB), the materials should be tested for the following quality requirements prior to delivery to the subject project, per the current `Greenbook,' 2009 Edition with the 2011 Supplement, and appropriate procedures as well as the required gradation and other requirements: TEST TEST METHOD NO. QUALITY REQUIREMENT Resistance Calif. Test 301 78 Minimum' (R- Value) Sand Calif. Test 217 35 Minimum Equivalent HILLTOP GEOTECBNICAL, INC. 504 -A05.9 December 23, 2011 Page 78 ON TEST TEST QUALITY METHOD NO. REQUIREMENT Percent Wear' 100 Revolutions ASTM C131 15 Maximum 500 Revolutions 52 Maximum Gravel Particles3, ( %) Calif. Test 202 15 Maximum 1. R- Value requirement may be waived if Sand Equivalent is 40 or more. 2. The percentage wear requirements may be waived if the material has a minimum Durability Index of 40 in accordance with CALTRANS Test Method 229. 3. Gravel is defined as particles with no more than one (1) fractured face. A `Greenbook' CMB may contain broken or crushed asphalt concrete or Portland Cement concrete and may contain crushed aggregate base or other rock materials. The CMB may contain no more than 3.0 percent brick retained on the # 4 sieve by dry weight of the total sample. Samples of the proposed aggregate base using reclaimed material should be sampled from the manufacturer's stockpiles and tested prior to delivery to the project. The samples should be obtained at a time as near the delivery to the project as possible but would allow enough time to complete the testing and report the results before delivery to the site. Samples should again be obtained and tested for quality compliance from the materials delivered to the project. In addition, per the current CALTRANS Standard Specifications, "No single aggregate grading or Sand Equivalent test shall represent more than 500 cubic yards or one (1) days production, whichever is less." ::_ . HILLTOP GEOTECHNICAL, INC. _. . 504 -A05.9 December 23, 2011 Page 79 Concrete gutters should be provided at flow lines in paved areas. Pavements should be sloped to permit rapid and unimpaired flow of runoff water. In addition, paved areas should be protected from moisture migration and ponding from adjacent water sources. Saturation of aggregate base and/or subgrade materials could result in pavement failure and/or premature maintenance. The gutter material and construction methods should conform to the current standards of the City of La Quinta, Riverside County, California. POST - GRADING CRITERIA Earth materials generated from the excavation of foundations, utility trenches, swimming pools and/or spas, etc., to be used on -site, should be moisture conditioned to optimum moisture content to 3.0 percent above optimum moisture content and compacted to 90 percent or greater of the maximum dry density for the material type as determined by current ASTM D1557 procedures when it is to be placed under floor slabs, under hardscape areas, and/or in paved areas. The placement of the excess material should not alter positive drainage away from structures and/or off the lot and should not change the distance from the weep screed on the structure to the finished adjacent earth material grade per the `Finish Surface Drainage Recommendations' presented in a subsequent section of this report, the project plans, or the 2010 CBC. SLOPE MAIN'T'ENANCE AND PROTECTION RECOMMENDATIONS Although the design and construction of slopes are planned to create slopes that possess stability against mass rotational failure, surficial slumping, creep, and pop -outs, certain factors are beyond the influence of the project Geotechnical / Geologic Consultant. Earth material slopes are subject to some erosion when subjected to sustained water application. To reduce long term erosion, the HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 80 following recommendations for slope protection and maintenance should be considered when planning, designing, and implementing slope erosion methods: • Surface water should not be allowed to flow over the on -site natural or proposed man -made slopes other than incidental rainfall and irrigation. Alterations of manufactured or natural slopes, top of slope berms, and/or pad gradients should not be allowed that will prevent pad and roof run -off from the structures from being expediently directed to approved disposal areas and away from the tops of slopes. • Surface drainage should be positively maintained from the rear yard, through the side yards, and to the street or storm drain in a non - erosive manner. ";m: • Top of slope berms should be constructed and compacted as part of finish grading of the lots and should be maintained by the individual lot owners and/or home owners association. The recommended drainage patterns should be established at the time of finish grading and maintained throughout the life of the proposed development. • Concentrated surface waters entering the subject lots from off -site sources should be collected and directed to a permanent drainage system. • The individual lot owners and/or home owners association are responsible for the maintenance and cleaning of the interceptor ditches, drainage terraces, downdrains and other drainage devices that have been installed to .promote slope stability. • It is recommended that slopes be planted with light - weight ground cover, shrubs and trees that possess deep (5.0 feet or greater), dense root structures that require minimal ofirrigation (drought resistance). It should be the responsibility of the Landscape Architect or other suitably qualified individual to provide such plants initially and of the individual lot owners and/or home owners association to maintain such planting. Alteration ofthe planting scheme is at the individual lot owner and/or home owners association risk. • If automatic sprinkler systems are installed their use should be adjusted to account for natural rainfall. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 81 • The individual lot owners and/or home owners association should establish a program for the elimination of burrowing animals. This should be an on -going program to protect slope stability. • The individual lot owners and/or home owners association should observe the lot drainage during heavy precipitation periods as this is often when trouble occurs. Problems such as gullying or ponding should be corrected as soon as practicable. • High moisture content in slope earth materials is a major factor in slope erosion and slope failures. Therefore, precautions should be taken to minimize earth material saturation. Leakage from pools, waterlines, irrigation systems, etc. or bypassing of clogged drains should be promptly repaired. ra The above guidelines are provided to mitigate slope maintenance and protection problems and should be included in information packets to individual home buyers and/or home owners association, when applicable, by the project developer. The above guidelines are general maintenance and design procedures but may be superseded under specific direction of a licensed Landscape Architect or other suitably qualified individual. UTILITY TRENCH RECOMMENDATIONS Utility trenches within the zone of influence of foundations or under building floor slabs, exterior hardscape, and/or pavement areas should be backfilled with documented, compacted earth material. Utility trenches within the building pad and extending to a distance of 5.0 feet beyond the building exterior footings should be backfilled with on -site or similar earth material. Where interior or exterior utility trenches are proposed to pass beneath or parallel to building, retaining wall, and/or decorative concrete block perimeter wall footings, the bottom of the trench should not be located below a 1H:1V (Horizontal to Vertical) plane projected HILLTOP GEOTECHNICAL, INC. i 504 -A05.9 December 23, 2011 Page 82 downward from the outside bottom edge of the adjacent footing unless the utility lines are designed for the footing surcharge loads. Trench Excavation It is recommended that utility trench excavations be designed and constructed in accordance with current OSHA regulations. These regulations provide trench sloping and shoring design parameters for trenches up to 20 feet in vertical depth based on a description and field verification of the earth material types encountered. Trenches over 20 feet in vertical depth should be designed by the Contractor's Engineer basted on site specific geotechnical analyses. For planning purposes, we recommend that the following OSHA earth material type designations and temporary slope inclinations be used: EARTH OSHA SOIL TEMPORARY SLOPE MATERIAL TYPE* INCLINATION (H:Y) * * Undocumented Fill C 1.5:1 Compacted Fill C 1.5:1 Alluvium C 1.5:1 Type `C': Cohesive soils with an unconfined compressive strength of 0.5 tsf or less: or Granular soils including sands, gravels, loamy, clayey or silty sands, etc. ** Steepest allowable slopes for excavations less than 20 feet in vertical height. Slopes for excavations greater than 20 feet in vertical height should be designed by a Registered Professional Engineer with experience in Geotechnical Consulting and Soil Mechanics. Excavations of less than 5.0 feet in depth may also be subject to collapse due to water, vibrations, previously disturbed earth materials, or other factors and may require protection for workers such as temporary slopes, shoring, or a shielding protective system. The excavations should be observed by a qualified, competent HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 83 person (as defined in the current OSHA regulations) looking for signs of potential cave -ins on a daily basis before start of work, as needed throughout the work shifts, and after every rainstorm or other hazard - increasing occurrence. Surcharge loads (i.e., spoil piles, earthmoving equipment, trucks, etc) should not be allowed within a horizontal distance measured from the top of the excavation slope equivalent to 1.5 times the vertical depth of the excavation. Excavations should be initially observed by the project Geotechnical / Geologic Consultant and/or his representative to verify the recommendations presented or to make additional-.r,.ecommendations to maintain stability and safety. Moisture variations, differences in the cohesive or cementation characteristics, or changes in the coarseness of the deposits may require slope flattening or, conversely, permit steepening upon review and appropriate testing by the project Geotechnical / Geologic Consultant and/or his representative. The excavations should be observed by a qualified, competent person (as defined in the current OSHA regulations) looking for signs of potential problems on a daily basis before start of work, as needed throughout the work shifts, and after every rainstorm or other hazard - increasing occurrence. Deep utility trenches may experience caving which will require special considerations to stabilize the walls and expedite trenching operations. Surface drainage should be controlled along the top of the construction slopes to preclude erosion of the slope face. If excavations are to be left open for long periods, the slopes should be sprayed with a protective compound and/or covered to minimize drying out, raveling, and/or erosion of the slopes. Utility Line Foundation Preparation If the utility trench excavation bottom is in material that is not suitable for support of the utility pipe, the material should be removed to a minimum depth of HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 84 j, 1.0 foot below the bottom of the pipe and replaced with concrete slurry, sand, or crushed gravel meeting the following appropriate gradation limits. SIEVE SIZE CRUSHED ROCK OR GRAVEL (PERCENT PASSING) 1" 100 3/4" 90 -100 1//" 30 -60 3/8" 0 -20 No.4 0 -5 SIEVE SIZE SAND (PERCENT PASSING) 3/8" 100 No. 4 75 -100 No. 30 12 -50 No. 100 5 -20 No. 200 0 -15 Most of the granular native earth materials encountered on the subject site are not expected to meet the above granular earth material criteria. It is recommend, that where the bottom of the pipe foundation excavation is loose or soft, the foundation earth materials be removed to firm materials as determined by the Engineer. This condition would likely only apply where fill underlies the pipe in localized areas along a utility alignment. If firm material is not encountered within 24 inches of the bottom of the pipe zone, the contractor may then elect to stabilize the trench bottom with 24 inches of crushed rock as HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 85 described above. Alternately, soft or loose material may be excavated to firm earth material and the overexcavation replaced with select earth material. The bottom of the utility trench excavation should be proof compacted to 90 percent or greater relative compaction prior to placement of compacted fill. Maximum dry density and optimum moisture content for compacted materials should be determined according to current ASTM D1557 procedures. Prior to placement of trench slurry or crushed rock, the bottom need only be cleaned of loose materials created by the excavation process. Where the bottom of the trench contains rocks or hard objects protruding above a depth of 6.0 inches below the pipe bottom, such objects should be removed or broken and any resulting cavities filled to produce a smooth surface. Bedding Requirements It is recommended that the pipe be bedded on either clean sand, gravel, crushed rock or any approved suitable material in order to provide a smooth, firm, and uniform foundation for the pipe. The pipe bedding material, thickness, shaping, and placement should satisfy the design requirements as determined by the design Civil Engineer and/or in accordance with Section 306 -1.2.1 of the 2009 Edition of the `Greenbook' with the 2011 Supplement. The majority of the man -made fills and alluvial soils on the subject site may not be suitable to be used as bedding and pipe zone backfill materials depending upon the bedding and pipe zone backfill specifications required by the project designer and/or the agency having jurisdiction over the water line. HILLTOP GEOTECMOCAL, INC. 504 -A05.9 December 23, 2011 Page 86 Trench Zone Backfill The excavated earth materials from the trench may be used as backfill in the trench zone unless more restrictive specifications are required by the design engineer or the permitting agency. The trench backfill material should consist of approved earth materials free of trash debris, vegetation or other deleterious matter, and oversize particles (i.e., 12 inch in maximum dimension). Trench zone backfill should be compacted to 90 percent or greater relative compaction. Maximum density and optimum moisture content for compacted materials should be determined according to current ASTM D1557 procedures. Trench backfill material should be placed in a lift thickness appropriate for the type of backfill material and compaction equipment used. Backfill material should be brought to optimum moisture content to 3.0 percent above optimum moisture content and compacted to 90 percent or greater relative compaction by mechanical means. Jetting or flooding of the backfill material will not be considered a satisfactory method for compaction. Maximum dry density and optimum moisture content for backfill material should be determined according to current ASTM D1557 procedures. FINISH SURFACE DRAINAGE RECOMN ENDATIONS Positive drainage should be established away from the tops of slopes, the exterior walls of structures, the back of retaining walls, trash enclosure walls, decorative concrete block walls, etc. Finish surface gradients in unpaved areas should be provided next to tops of slopes and buildings to guide surface water away from foundations, hardscape, pavement, and from flowing over the tops of slopes. The surface water should be directed toward adequate drainage facilities. Ponding of surface water should not be allowed next to structures or on pavements. Design criteria for finish lot drainage away from structures and off the lots should be HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 87 determined by the project Structural Engineer designing the foundations and slabs in conjunction with the project Civil Engineer designing the precise grading for lot drainage, respectively, in accordance with the 2010 CBC and/or the current City of La Quinta, California codes and ordinances and the earth material types and expansion characteristics for the earth materials contained in this report. Finished landscaped and hardscape or pavement grades adjacent to the proposed structures should maintain a vertical distance below the bottom elevation of the weep screed per the 2010 CBC and/or the current City of La Quinta codes and ordinances. Landscape plants with high water needs and trees should be planted at a distance away from the structure equivalent to or greater than the width of the canopy of the mature tree or 6.0 feet, whichever is greater. Downspouts from roof drains should discharge to a permanent all- weather surface which slopes away from the structure. Downspouts from roof drains should not discharge into planter areas immediately adjacent to the building unless there is positive drainage out of the planter and away from the structure in accordance with the recommendations of the project foundation and slab designer and/or the project Civil Engineer designing the precise grades for the lot drainage. PLANTER RECOMMENDATIONS Planters around the perimeter of the structures should be designed so. that adequate drainage is maintained and minimal irrigation water is allowed to percolate into the earth materials underling the buildings. This should include enclosed or trapped planter areas that are created as a result of sidewalks. Planters with solid bottoms, independent of the underlying earth material, are recommended within a distance of 6.0 feet from the buildings. The planters should drain directly onto surrounding paved areas or into a designed subdrain system. If planters are raised above the surrounding finished grades or are placed against the building structure, the interior walls of the planter should be waterproofed. HILLTOP GEOTECHNICAL, .INC. a r 504 -A05.9 December 23, 2011 Page 88 LIMITATIONS REVIEW, OBSERVATION, AND TESTING The recommendations presented in this report are contingent upon review of final plans and specifications for the project by HGI The project Geotechnical / Geologic Consultant should review and verify in writing the compliance of the final grading plan and the final foundation plans with the recommendations presented in this report. It is recommended that HGI be retained to provide continuous Geotechnical / Geologic Consulting services during the earthwork operations .(i.e., rough grading, utility trench backfill, subgrade preparation for slabs -on -grade and pavement areas, finish grading, etc.) and foundation installation process. This is to observe compliance with the design concepts, specifications and recommendations and to allow for design changes in the event that subsurface conditions differ from those anticipated prior to start of construction. If HGI is replaced as Geotechnical / Geologic Consultant of record for the project; the work on the project should be stopped until the replacement Geotechnical / Geologic Consultant has reviewed the previous reports and work performed for the project, agreed in writing to accept the recommendations and prior work performed by HGI for the subject project, or has submitted their revised recommendations. UNIFORMITY OF CONDITIONS The recommendations and opinions expressed in this report reflect our understanding of the project requirements based on an evaluation of subsurface earth material conditions encountered.at the subsurface exploration locations and the assumption that earth material conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 89 may be influenced by undisclosed or unforeseen variations in earth material conditions that may occur in intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the HGI so that we may make modifications, if necessary. CHANGE IN SCOPE HGI should be advised of any changes in the project scope of proposed site grading so that it may be determined if recommendations contained herein are valid. This should be verified in writing or modified by a written addendum. t _ TIME LIMITATIONS The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in the State -of -the -Art and/or government codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two (2) years without a review by HGI verifying the validity of the conclusions and recommendations. PROFESSIONAL STANDARD In the performance of our professional services, we comply with the standard of care and skill ordinarily exercised under similar circumstances by members of the geotechnical / geologic professions currently practicing under similar conditions and in the same locality. The client recognizes that subsurface conditions may vary from those encountered at the locations where our surveys and exploratory excavations were made, and that our data, interpretations, and recommendations HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page 90 are based solely on information obtained by us. We will be responsible for those data, interpretations, and recommendations, but should not be responsible for interpretations by others of the information presented and/or developed. Our services consist of professional consultation and observation only, and other warranties, expressed or implied, are not made or intended in connection with work performed by HGI or by the proposal for consulting or other services or by the furnishing of oral or written reports or findings. CLIENT'S RESPONSIBILITY ,r. It is the responsibility of the client and/or the client's representatives to ensure, that information and recommendations contained herein are brought to the attention of the Engineers and Architect for the project and incorporated into project plans and specifications. It is further their responsibility to take measures so that the contractor and his subcontractors carry out such recommendations during construction. HILLTOP GEOTECHNICAL, INC. a APPENDIX A HILLTOP GEOTECHNICAL, INC. REPORT OF GEOTECHNICAL STUDY PROPOSED RESIDENTIAL SUBDIVISIONS TENTATIVE TRACT NOS. 31732 & 31733 SOUTHEAST CORNER OF MONROE STREET AND AVENUE 60 LA QUINTA AREA OF RIVERSIDE COUNTY, CALIFORNIA PROJECT NO.: 504 -A05 REPORT NO.: 2 APRIL 22, 2005 SUBMITTED TO: KB HOME 41 -517 GORE STREET INDIO, CA 92201 PREPARED BY: HILLTOP GEOTECHNICAL, INC. 786 SOUTH GIFFORD AVENUE SAN BERNARDINO, CA 92408 0 Reference: MDS Consulting, Signed on May 12,'2004 with no revisions, Tentative Tract Map No. 31732, Scale 1' =60', Sheet 1 of 1. M q i LEGEND B -7 Approximate Location of Exploratory Excavation. Ql Quaternary Lake Deposits f. `r I f i j Scale 1 "= 200' EXPLORATORY EXCAVATION LOCATION PLAN By: JM Date: 4/05 i E '� o ,. �;� :�N . �. ,:. �. h q. f °a� .lonfm.e.,,;zrt �.. :: .- � �-'.•�.... ... rmc>m:weaue , � ,I ::� � � pv,T I •>aJl ..IPOC >E .. , �.'` .- +,s.f ..�...,T • 1ftL,T 1 ,.» ' . `y. � - ,e _ � ° aq• Yo411. _.. Y- ,yecaT fA .,r, ..,, I . SLR. : -.I -O I` M' ���' r— •�• w /.• ' ��,• nr I.f I t aoo -- — IF ^��. :y,• -lr —y r .:( laz "S I 1 �- .,r O V u• � �' ' rO i :.$,1 V. °ism isi � •� � �a� ',x.•; . :X ' ell l�.l � � ' �• '{ �`I ® ` %' • ® :� Ii . 11 (� I 1 © ( Y ;. ' .A. j `•. , n^ u o ® 4L " ' ! Y ,14� ,`S' ✓�'� LEGEND ' ',..a � - Toy. ���'�`'1 �• '°.,• - -'�-�. . / D -7 Approximate Location of 17- �",P ' ' ° ` `' ®; ® o o ' Y Exploratory Excavation. P. i , I 7° . ;1 • Q • "© ® �'� R �° Ql Quaternary Lake Deposits o o � -� �•,- ie .Y iz• .i � ®-:' I - ( ` %ice ili 'i• iM f � •. \ d. \ �!: -� I I' _� �( ( .—� •.p �— °s=+ � _o_,._ � .` .'� �,�.\.. ``� mss, �'' yl' � . D I. CEO QED 0D g �� � 1 i O ,.� ars .1 ili '3' �L' ' ' im• / . •• /`5'�'- f I ' I �::, ' dQu • I .. a°+ uk m Toi � 9f +f ( yr. 1 °ail , ��' i' . $ iz • is \ • ' i • a 'ii / ,� �, y.:.4 \ , • r n A"',s' is'i n n m ~°°,i' ' • e ,I ;ss —u — — '" f a • Q -T ,1 (� YR.�•'i •1 - `:� -.'-•4 -•S- •i5'�$ "X -SC -i �,' ~y` :' t - A '.70rJYj�`�7. �}�,j��l Td 1� {q,,,� "' ��rll "f� ^� •' ..'„tt �•� ^�' jjr % 4: 1 Scale 1 "= 200' Reference: MDS Consulting, Undated with no revisions, Tentative Tract Map No. 31733, Scale EXPLORATORY EXCAVATION LOCATION PLAN 1' =60', Sheet 1 of 1. By: JM Date: 4/05 HILLTOP GEOTECHNICAL I.CONPO.ATEO Project No.: 504 -A05.2 Plate No.: lb SUBSURFACE EXPLORATION LEGEND UNIFIED SOIL CLASSIFICATION SYSTEM CONSISTENCY/ RELATIVE . Visual - Manual Procedure (ASTM D2488) DENSITY MAJOR DIVISIONS GROUP TYPICAL NAMES CRITERIA dry to the touch. SYMBOLS 5-12% S - SPT Sample Moist Damp but no visible moisture. Little 12-25% GW Well Graded Gravels and Reference: 'Foundation Engineering', Peck, Hansen, 25-50% CK - Chunk Sample Clean Gravel -Sand Mixtures, Little or Thomburn, 2nd Edition. Gravels Gravels N - Nuclear Gauge Test no Fines Poorly Graded Gravels and HILLTOP GEOTECHNICAL, INC 50 % or more PLATE NO.2 of Coarse GP Gravel -Sand Mixtures, Little or Standard Penetration Test Fraction no Fines Granular Soils Retained on Coarse- No. 4 Sieve GM Silty Gravels, Gravel- Sand -Silt Penetration Resistance, Relative Grained Gravels Mixtures" N, (Blows/ Foot) Density Soils* with Fines GC Clayey Gravel, Gravel -Sand- Clay Mixtures" 0-4 Very Loose More than SW Well Graded Sands and Gravely Sands, Little or no Fines 50% Retained 4-10 Loose on No. 200 Clean 10-30 Medium Poorly Graded Sands and Sieve Sands Sands SP Gravely Sands, Little or no Fines 30-50 Dense More than 50 % of Coarse Sands SM Silty Sands, Sand -Silt > 50 Very Dense Fraction Passes with Mixtures" No. 4 Sieve Fines SC Clayey Sands, Sand -Clay ;Ff. Mixtures" Standard Penetration Test ML Inorganic Silts, Sandy Silts, Rock Flour Cohesive Soils CL Inorganic Clays of Low to Silts and Clays Penetration Consistency Unconfined Medium Plasticity, Gravelly Resistance, N, Compressive Liquid Limits 50 % or less Clays, Sandy Clays, Silty Clays, (Blows / Foot) Strength, Fine Lean Clays (Tons / Sq. Grained t Ft,) Soils* OL Organic Silts and Organic silty Clays of Low Plasticity <2 Very Soft <0.25 50 % or 2-4 Soft 0.25-0.5 MH Inorganic Silts, Micaceous or more Passes No. Diatomaceous silts, Plastic Silts 4 - 8 Medium 0.5-1.0 CH Inorganic Clays of High Plasticity, Fat Clays 200 Sieve Silts and Clays 8-15 stiff 1.0-2.0 Liquid Limits Greater than 50 OH Organic Clays of Medium to % 15-30 Very Stiff 2.0-4.0 High Plasticity >30 Hard > 4.0 Highly Organic Soils PT Peat, Muck, or Other Highly Organic Soils 0 Based on material passing the 3 -inch sieve. ** More than 12% passing the No. 200 sieve; 5% to 12% passing No. 200 sieve requires use of duel symbols (i.e., SP -SM., GP -GM, SP -SC, GP -GC, etc.); Border line classifications are designated as CIVC1, GM/SM, SP /SW, etc. U.S. Standard Sieve Size 12" . 3" 3/4" #4 #10 #40 9200 Unified Soil Classification Designation Boulders Cobbles Gravel Sand Silt and Clay Coarse Medium Fine Coarse Fine Moisture Condition Material Ouantity Other Symbols Dry Absence of moisture, dusty, Trace <5% C - Core Sample dry to the touch. Slightly 5-12% S - SPT Sample Moist Damp but no visible moisture. Little 12-25% B - Bulk Sample Wet Visible free water, usually Some 25-50% CK - Chunk Sample below the water table. R - Ring Sample N - Nuclear Gauge Test ` V - Water Table . HILLTOP GEOTECHNICAL, INC PLATE NO.2 r tv m O in O w (n 1W trJ O t7' ill �3 O CD co 0 CD z 0 0 :1 cp I CD Q. CD CD CL CD co I 0 C* cn tJ 0-0 v o, v, w N . \0 00 . . . . . o. . . v, . . . w . . . . DEPTH (FT.) Igg N SAMPLE TYPE 00 PENETRATION RESISTANCE II ICl) SOIL cn CLASSIFICATION DRY DENSITY il.) 00 m (PCF) go MOISTURE CONTENT 'O LITHOLOGY GROUNDWATER CD CD c� CD CD cn 0. 1 , CD -Z L� > § m co M. CD w ',0 > ST co (n fD -< o CD co En CA C) 0 CD CL (n C7. II nI. 0 CD CD FD cp 0 I 0 C* cn tJ BORING NO. B-2 - PROJECT NUMBER: 504-A05.2 Bottom of boring at 20.0 feet- Nn ormindwnter mr-mintp.md Rnrino, Kqnk-fillprl with P.yrnuntp.rl m5ifi-•;n1c HiLuop GEOTECHNICAL I ......... ". SUBSURFACE EXPLORATION LOG z O DATE: 4/8/05 _SS PLATE NO. 4 U x z U w a� FW z z W U I z ou 0 9 DESCRIPTION En U I go Cl 3 ML QI QUATERNARY LAKE DEPOSITS: 6 9 97.0 2.1 Fine sandy silty, trace fine gravel, trace roots in upper 18 inches; Gray Brown; Moist; Stiff. Silty fine sand; Gray; Moist; Medium dense. 2 8 SM 300 rt - WS, 4 16 5 108.3 1.2 5 6 N, 0 7 10 106.8 2.6 Sandy clay; Gray to brown; Moist; Medium stiff. 7 4 CL 8R 4 9 4 83.5 34.2.-,' Silty fine to medium sand; Brown; Moist; Medium dense. 10 4 SM fR 11 9 9 116.4 5.4 — Fine sandy —Silt; Brown; Moist; Medium —stiff.— 12 13� 3 ML 14 15 R 16 4 5 SM Silty fine sand; Brown; Moist; Medium dense. 17 18 6 19 UPM 1.0 20 9 Bottom of boring at 20.0 feet- Nn ormindwnter mr-mintp.md Rnrino, Kqnk-fillprl with P.yrnuntp.rl m5ifi-•;n1c HiLuop GEOTECHNICAL I ......... ". SUBSURFACE EXPLORATION LOG ELEVATION: f 418.5 BY: DATE: 4/8/05 _SS PLATE NO. 4 "I ko 1001 1—,l I- (.h I- -- I I :, . 1.1 . . 1-11 . . . 1-1 . 1-1 . J . . �, 1 . 1,, . 1 DEPTH (FT.) 0111111", SAMPLE TYPE I I a, I c� Pl 4P 00 LA o oo w c, c, cA w PENETRATION RESISTANCE b cn 10 cn cn !7? cn SOIL CLASSIFICATION DRY DENSITY --a w 00 (PCF) N MOISTURE CONTENT ( %) LITH6LOGY GROUNDWATER co c� -5 ni 10 :,:,, c co p CD on > CD CD 0 CD CD a ° I 0 I En x � � a � r`.,.1I 2. cn CD o'I 0 2.1 (A III 0 w l3I ?? I y M"� 0.1 1 CD co cn • I O 0 0 0 0 0 • • 0 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 • 0 0 0 0 0 BORING NO. B-4 PROJECT NUMBER: 504-A05.2 Haxmp GEoTEcHNir_AL SUBSURFACE EXPLORATION LOG z O DATE: 4/8/05 PLATE NO. 6a 0 z aH 0 0 z < z co W W z 0 &_ 0 W DESCRIPTION 2 M L QI QUATERNARY LAKE DEPOSITS: 1 3 4 3 7 95.2 15.3 Fine sandy silt; Brown; Moist; Medium stiff to stiff. 2 3 , C�ffi 4 10 95.3 4.1 Silty fine sand; Brown; Moist; Loose. 5 3 SM 6 4 5 7", 95.3 4.1 Fine sandy silt; Brown; Moist; Stiff. 7 3 ML 8 • 6 9 9 102.8 19.7 Clayey fine sand; Olive brown; Moist; Medium dense. 10 5 SC I 9 16 110.0 3.9 Silty fine sand, trace mica; Brown; Moist; Medium dense. 12 13 5 SM 14 15 16 10 14 SM Silty fine sand; Brown to gray; Moist; Very loose to loose. 17_ 18 1 19 261 Haxmp GEoTEcHNir_AL SUBSURFACE EXPLORATION LOG ELEVATION: t 416.5 BY: SS DATE: 4/8/05 PLATE NO. 6a v �n o= z r r d trJ C� H O z 0• o � A ci N N � O z O o z O c ran w p w � ] C) -c oo w w N N 00 ' (7% N N N � w DE PTH (T.) ice* �VimjL �: Vi?�n SAMPLE TYPE v, w PENETRATION RESISTANCE r cnl SOIL CLASSIFICATION DRY DENSITY (PCF) MOISTURE CONTENT ( %) rt A LITHOLOGY GROUNDWATER I '� co cn vii OI CD Y -ml CD l a l 0 N I I CD � r o I a S v4 �5 O o C � w O N cr O O Y� J En o o .� En cn V ? o ►� CD CD �I n y 1 h. O H 0 0 m �i z 9 ly C H A z 00 o � r a CrJ ro � O z � o z O rn - - 00 v J °v V �D P co -;- -01 -P LA A .4. P a DEPTH (FT.) .y �N �;�y�' SAMPLE TYPE h ���q rn w v 0\ w v I cn w N PENETRATION RESISTANCE Cn SOIL CLASSIFICATION DRY DENSITY (PCF) MOISTURE CONTENT( %) n Q r+ LITHOLOGY GROUNDWATER 04 Sn A o a a O CD to cu ° a � - o o .ova (D G1 C �0� o ° (D 0 CD CD CD 0 'd a l En cn O CD CD w' CD CD a , bd 1 Z O H z x 0 Y 0 ci 4 cn lJ DEPTH (FT.) kn-ng SAMPLE TYPE 00 Ull 00 Un U.) oo a, w PENETRATION RESISTANCE SOIL CLASSIFICATION DRY DENSITY tQ 00 (PCF) 5r\ N MOISTURE 00 CONTENT ( %) 'o— LITHOLOGY GROUNDWATER "TJ cn rA 'o CD > 0 01 0 ch CD CD CD CD 0 ci 4 cn lJ Cd O C> 0 CD CD I CD FL CD R. 0 cD C> DEPTH (FT.) ... ..... .... ... SAMPLE TYPE LA taw I U00 ON tA U.) 00 UJ 00 er PENETRATION RESISTANCE nl cn SOIL CLASSIFICATION e-0-0\ t jo0 o DRY DENSITY (PCF) 00 O N MOISTURE %) CONTENT ( Q LITHOLOGY GROUNDWATER 0- cn CD CD CD sp CD CD > cl. Q- CD CD cn cn R- 0 CD C D m Q cn 0 w CD CD 7,1 o o ST o C.1 o r- 0 CD o CD 2. O H.. 0 C-( Cd (A BORING NO. B -7 PROJECT NUMBER: 504 -A05.2 AL.. HILLTOP Geo'rECHNICAL SUBSURFACE EXPLORATION LOG z z G DATE: 4/8/05 PLATE NO. 9 a w Fz v aH o 3 �W a z w W o a a U o o H a ]DESCRIPTION Ca In a, v� U 0 � U a t7 • 4WER, 3 ML Ql QUATERNARY LAKE DEPOSITS: 1 6 7 99.2 4.8 — Fine sandy silt, trace roots in upper 18 inches; Brown; Stiff; Moist. — Silty fine sand; Gray brown; Moist; Loose. 2 2 SM — 3 r. 3 4 4 89.3 — 102.5 4.3 — 8.3 — — — — — — — — — — Fine sandy silt; Brown; Moist; Stiff. Fine sand, trace silt; Gray; Moist; Loose. 5 — 5 6 9 — ML — — R' 6." 5 SP 8 R 9 7 106.7 2.1 Fine sandy clay, trace silt; Dark gray; Moist; Medium dense. 10 3 CL R 4 >; 7 95.8 24.8 Silty fine sand, trace mica; Brown; Moist; Medium dense. 12 13 14 SM 15 f� 16 12 14 17 Bottom of boring at 16.5 feet. No groundwater encountered. Boring backfilled with excavated materials. 18 19 20 AL.. HILLTOP Geo'rECHNICAL SUBSURFACE EXPLORATION LOG ELEVATION: f 417.5 BY: SS DATE: 4/8/05 PLATE NO. 9 April 22, 2005 Project No.: 504 -A05.2 SUMMARY OF LABORATORY TEST RESULTS EXPANSION INDEX TEST RESULTS (ASTM D4829 Test Method) SAMPLE SOIL DESCRIPTION EXPANSION INDEX EXPANSION POTENTIAL* 0 -3' Brown to gray fine sandy silt (ML) 39 Low , 0'-3' L Brown fine sandy silt (ML) 39 Low B-6, , 0' -3' Brown fine sandy silt (ML) 37 Low * Per Table 18 -I -B, `Classification of Expansive Soil,' in the 2001 California Building Code (CBC). SOLUBLE SULFATE TEST RESULTS (California Test Method No. 417) * Per Table 19 -A -4, 'Requirements for Concrete Exposed to Sulfate - Containing Solutions,' in the 2001 CBC. PLATE NO. 10 HILLTOP GEOTECHNICAL, INC. SOLUBLE SULFATE SAMPLE SOIL DESCRIPTION SULFATE EXPOSURE" B -3, 0' -3' Brown to gray fine sandy silt (ML) 0.099 Negligible B -4, 0. 1-T Brown fine sandy silt (1VII.,) 0.057 Negligible B -6, 0' -3' Brown fine sandy silt (ML) 0.021 Negligible * Per Table 19 -A -4, 'Requirements for Concrete Exposed to Sulfate - Containing Solutions,' in the 2001 CBC. PLATE NO. 10 HILLTOP GEOTECHNICAL, INC. April 22, 2005 Project No.: 504 -A05.2 SUMMARY OF LABORATORY TEST RESULTS PERCENT PASSING #200 SIEVE TEST (ASTM D1140 Test Method) SAMPLE SOIL DESCRIPTION PERCENT PASSING #200 SIEVE B -3, 0' -3' Brown to gray fine sandy silt (ML) 58 B -4, 0' -3' Brown fine sandy silt (ML) 69 B-4,3.5'-4.0' Brown fine sandy silt (ML) 76 B-4,6.0'-6.5' Brown silty fine sand (SM) 26 B -4, 8.5' -9.0' Brown fine sandy silt (ML) 83 B -4, 11.0' -11.5' Olive brown clayey fine sand (SC) 20 B-4,16.0'-16.5' Brown silty fine sand, trace mica (SM) 23 B -4, 21.0' -21.5' Brown to gray silty fine sand (SM) 46 B-4,31.0'-31.5' Brown silty fine to medium sand (SW 35 B -4, 36.0' -36.5' Gray to olive brown fine sandy clay (CL) 88 B-4,41.0'-41.5' Gray silty fine sand (SW 37 B -4, 46.0' -46.5' Gray slightly silty fine to coarse sand (SP -SM) 10 B-4,51.0'-51.5' Gray slightly silty fine to coarse sand (SP -SW 9 B -6, 0' -3' Brown fine sandy silt (ML) 51 PLATE N0. 11 HILLTOP GEOTECHNICAL, INC. April 22, 2005 Project No.: 504 -A05.2 SUMMARY OF LABORATORY TEST RESULTS CHEMICAL TEST RESULTS N.D. - Non Detected. Neg. - Negative. CONSOLIDATION TEST RESULTS (ASTM D2435 Test Method) REDOX RESISTIVITY SAMPLE SETTLEMENT AT CHLORIDE SAMPLE POTENTIAL Minimum pH SULFIDE (ppm) B -6, 3.5' -4.0' (mv) (ohm -cm) 0' -3' 239 5,226 6.6 Neg. 890 B -4, 0' -3' 228 2,938 6.0 Neg. 1,610 N.D. - Non Detected. Neg. - Negative. CONSOLIDATION TEST RESULTS (ASTM D2435 Test Method) * Percent collapse or swell measured when water added at 1,600 psf load during test procedure. PLATE NO. 12 HILLTOP GEOTECHNICAL, INC. PERCENT PERCENT SAMPLE SETTLEMENT AT COLLAPSE ( -) or 1,600 PSF LOAD SWELL ( +)* B-2,8.5'-9.01 2.0 +0.2 B -6, 3.5' -4.0' 2.0 -0.8 * Percent collapse or swell measured when water added at 1,600 psf load during test procedure. PLATE NO. 12 HILLTOP GEOTECHNICAL, INC. 0.0 4.0 z 0 A s.0 a 0 U 12.0 16.0 0.1 1 1.6 3.2 10 LOAD (kips /ft2) CONSOLIDATION TEST RESULTS B -4, 0' -3' (Sample remolded to 90% relative comapction SAMPLE: at optimum moisture content) SOIL DESCRIPTION: Brown fine sandy silt (ML) HILLTOP GEOTECHNICAL BY: SS DATE: 4/05 urcocoon•rr,o JOB NO.: 504 -A05.2 PLATE NO. 13 Water Added i i i t i • • 3 i , F I I g i f i I t • I I i 1 a i i CONSOLIDATION TEST RESULTS B -4, 0' -3' (Sample remolded to 90% relative comapction SAMPLE: at optimum moisture content) SOIL DESCRIPTION: Brown fine sandy silt (ML) HILLTOP GEOTECHNICAL BY: SS DATE: 4/05 urcocoon•rr,o JOB NO.: 504 -A05.2 PLATE NO. 13 145 140 135 130 —125 E c 120 d A a, L A 115 110 105 100 95 0 5 10 15 20 25 30 Moisture Content ( %) Maximum Dry Density (Ib /ft3) 117.5 Optimum Moisture Content ( %) 14.5 Procedure A MAXIMUM DRY DENSITY / OPTIMUM MOISTURE CONTENT RELATIONSHIP TEST RESULTS SAMPLE: B -4, 0' -3' SOIL DESCRIPTION: Brown fine sandy silt (1VIL) HILLTOP GEOTECHNICAL BY: SS DATE: 4/05 JOB NO.: 504 -A05.2 IPLATE NO. 14 Plasticity Chart Sample P Soil Description P Liquid Plastic Plasticity Limit (%) Limit (%) Index B -1, 0' -3' Brown to gray fine sandy silt (ML) 29 23 6 ATTERBERG LIMIT TEST RESULTS BY: SS DATE: 4/05 HILLTOP GEOTECHNICAL JOB NO.: 504 -A05.2 PLATE NO.: 15 INCORPORATED GEOTECHNICAL REPORT OF GRADING PROPOSED RESIDENTIAL SUBDIVISIONS TENTATIVE TRACT NOS. 31732 AND 31733 SOUTHEAST CORNER OF MONROE STREET AND AVENUE 60 CITY OF LA QUINTA RIVERSIDE COUNTY, CALIFORNIA PROJECT NO.: 504 -005 REPORT NO.: 1 MARCH 8, 2007 SUBMITTED TO: KB HOME 36310 INLAND VALLEY DRIVE WILDOMAR, CA 92595 SUBMITTED BY: HILLTOP GEOTECHNICAL, INC 786 SOUTH GIFFORD AVENUE SAN BERNARDINO, CA 92408 March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA 504 -005.1 MAXIMUM DRY DENSITY / OPTIMUM MOISTURE CONTENT RELATIONSHIP TEST RESULTS (ASTM D1557 Test Method) SAMPLE MAXIMUM OPTIMUM NO. / SOIL DESCRIPTION PROCEDURE DRY MOISTURE DATE DENSITY CONTENT SAMPLED (pcf) M) 1 .: Brown silty fine to medium 10 -5 -05 sand, trace clay (SM) A 114.0 13.5 2 Brown silty fine to medium 10 -25 -05 sand, trace clay (SM) A 114.5 13.0 3 Gray -brown silty fine to 10 -25 -05 medium sand, trace clay A 121.0 12.0 (SM) Gray -brown fine to 4 medium sandy silt to A 119.5 13.5 10 -27 -05 sandy clay (ML/CL) (Import) 5 Gray -brown silty fine to 10 -27 -05 medium sand (SM) A 112.0 11.5 (Import) 6 Light brown fine to 11 -2 -05 medium sandy silt to A 117.5 13.5 sandy clay (ML/CL) 7 Light brown slightly silty 12 -12 -05 fine sand, trace organic A 108.0 15.5 material (SP -SM) 8 Gray -brown silty fine to 4 -10 -06 medium sand, some clay A 117.0 13.0 (SM) 9 Brown silty fine to coarse A 123.0 8.5 7 -11 -06 sand (SM) PLATE NO. 67 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA PERCENT PASSING #200 SIEVE TEST (ASTM D1140 Test Method) SAMPLE PERCENT NO. SOIL DESCRIPTION PASSING #200 SIEVE Max. #1 Brown silty fine to medium 32 sand, trace clay (SM) Max. #2 Brown silty fine to medium 40 sand, trace clay (SM) Gray -brown silty fine to Max. #3 medium sand, trace clay 21 (SM) Gray -brown fine to Max. #4 medium sandy silt to sandy 62 clay (ML/CL) (Import) Gray -brown silty fine to Max. #5 medium sand (SM) 14 (Import) Light brown fine to Max. #6 medium sandy silt to sandy 56 clay (ML/CL) Light brown slightly silty Max. #7 fine sand, trace organic 6 . material (SP -SM) Gray -brown silty fine to Max. #8 medium sand, some clay 24 (SM) Max. #9 Brown silty fine to coarse �,- sand (SM) * No test performed. PLATE NO. 68 HILLTOP GEOTECHNICAL, INC. March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA 504 -005.1 EXPANSION INDEX TEST RESULTS (ASTM D4829 Test Method) SAMPLE SOIL DESCRIPTION EXPANSION EXPANSION NO. INDEX POTENTIAL* Max. #1 Brown silty fine to medium 0 Very Low sand, trace clay (SM) Max. #2 Brown silty fine to medium 9 Very Low sand, trace clay (SM) Max. #3 Gray -brown silty fine to 0 Very Low medium sand, trace clay (SM) Gray -brown fine to medium Max. #4 sandy silt to sandy clay 32 Low (ML/CL) (Import) Gray -brown silty fine to Max. #5 medium sand (SM) 0 Very Low (Import) Light brown fine to medium Max. #6 sandy silt to sandy clay 18 Very Low (ML/CL) Light brown slightly silty fine Max. #7 sand, trace organic material 0 Very Low (SP -SM) Max. #8 Gray -brown silty fine to 3 Very Low medium sand, some clay (SM) Max. #9 Brown silty fine to coarse sand (SM) a` Per Table 18 -1 -B, `Classification f Expansive Soil,' in the 2001 California Building'Code (CBC). No test performed. PLATE N0.59 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) SAMPLE SOIL DESCRIPTION I SOLUBLE SULFATE NO. SULFATE ( %) EXPOSURE* Max. #1 Brown silty fine to medium 0.052 Negligible sand, trace clay (SM) Max. #2 Brown silty fine to medium 0.045 Negligible sand, trace clay (SM) Gray -brown silty fine to Max. #3 medium sand, trace clay 0.039 Negligible (SM) Gray -brown fine to medium Max. #4 sandy silt to sandy clay 0.248 Severe (ML/CL) (Import) Gray -brown silty fine to Max. #5 medium sand (SM) 0.027 Negligible (Import) Light brown fine to medium Max. #6 sandy silt to sandy clay 0.043 Negligible (ML/CL) Light brown slightly silty Max. #7 fine sand, trace organic 0.246 Severe material (SP -SM) Gray -brown silty fine to Max. #8 medium sand, some clay 0.035 Negligible (SM) Max. #9 Brown silty fine to coarse ** sand (SM) Per Table 19 -A -4, `Requirements for Concrete Exposed to Sulfate- Containing Solutions,' in the 2001 CBC. ** No test performed. PLATE NO. 70 4 4 HILLTOP GEOTECHNICAL, INC. March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE CHLORIDE TEST RESULTS (California Test 422) SAMPLE SOLUBLE NO. SOIL DESCRIPTION CHLORIDE (PPm) Brown silty fine to Max. #1 medium sand; trace clay 220 (SM) Brown silty fine to Max. #2 medium sand, trace clay 180 (SM) Gray -brown silty fine to Max. #3 medium sand, trace clay 320 (SM) Gray -brown fine to Max. #4 medium sandy silt to 380 sandy clay (ML/CL) (Import) Gray -brown silty fine to Max. #5 medium sand (SM) 100 (Import) Light brown fine to Max. #6 medium sandy silt to' 210 sandy clay (ML/CL) light brown slightly silty Max. #7 fine sand, trace organic _ 230 material (SP -SM) Gray -brown silty. fine to . . Max. #8 medium sand, some clay 790 (SM) Max. #9 Brown silty fine to coarse �. sand (SM) * No test performed. 504 -005.1 a PLATE NO. 71 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA EXPANSION INDEX TEST RESULTS (ASTM D4829 Test Method) LOT NO. EXPANSION INDEX EXPANSION POTENTIAL* Tract No. 31732 2 29 Low 12 11 Very Low 21 15 Very Low 30 0 Very Low 40 0 Very Low 50 18 Very Low 60 7 Very Low 70 56 Medium 78 38 Low 90 1 Very Low 102 0 Very Low 110 15 Very Low 117 0 Very Low 127 3 Very Low 137- 5 Very Low 147 0 Very Low 157 5 Very Low 165 50 Low 170 0 Very Low 180 3 Very Low PLATE NO. 72 HILLTOP GEOTECHNICAL, INC. March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA EXPANSION INDEX TEST RESULTS (ASTM D4829 Test Method) LOT NO. EXPANSION INDEX EXPANSION POTENTIAL* Tract No. 31732 (Cont.) 195 46 Low Per Table 18 -I -B, `Classification f Expansive Soil,' in the 2001 California Building Code (CBC). EXPANSION INDEX TEST RESULTS (ASTM D4829 Test Method) LOT NO. EXPANSION INDEX EXPANSION POTENTIAL* Tract No. 31733 4 20 Very Low 13 45 Low 19 10 Very Low 27 12 Very Low 35 1 Very Low 48 25 Low 51 0 Very Low 65 13 Very Low 70 18 Very Low 79 9 Very Low 92 0 Very Low 504 -005.1 PLATE NO. 73 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUAEVIARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA EXPANSION INDEX TEST RESULTS (ASTM D4829 Test Method) LOT NO. EXPANSION I INDEX I EXPANSION POTENTIAL* Tract No. 31733 (Cont.) 107 0 Very Low 118 31 Low Per Table 18 -I -B, `Classification f Expansive Soil,' in the 2001 California Building Code (CBC). SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE ( %) SULFATE EXPOSURE* Tract No. 31732 1 0.132 Moderate 2 0.123 Moderate 3 0.108 Moderate 4 0.117 Moderate 5 0.163 Moderate 6 0.155 Moderate 7 0.200 Severe 8 0.232 Severe PLATE NO. 74 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31732 (Cont.) 9 0.131 Moderate 10 0.156 Moderate 11 0.184 Moderate 12 0.192 Moderate 13 0.126 Moderate 14 0.083 Negligible 15 0.060 Negligible 16 0.068 Negligible 17 0.072 Negligible 18 0.068 Negligible 19 0.054 Negligible . 20 0.076 Negligible 21 0.152 Moderate 22 0.114 Moderate 23 0.049 Negligible 23 0.246 Severe 24 0.159 Moderate 24 0.216 Severe PLATE NO. 75 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733_ CITY OF LA QUINTA, ICA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31732 (font.) 25 0.024 Negligible 26. 0.023 Negligible 27 0.049 Negligible 28 0.030 Negligible 29 0.070 Negligible 30 0.012 Negligible 31 0.024 Negligible 32 0.048 Negligible 33 0.052 Negligible 34 0.142 Moderate 35 0.121 Moderate 36 0.246 Severe 37 0.098 Negligible 38 0.077 Negligible 39 0.092 Negligible 40 0.047 Negligible 41 0.060 Negligible 42 0.094 Negligible PLATE NO. 76 HILLTOP GEOTECHNICAL, INC. N March 8, 2007 SUAE14ARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31732 (Cont.) 43 0.092 Negligible 44 0.144 Moderate 45 0.180 Moderate 474'* 0.076 Negligible 48 0.073 Negligible 49 0.098 Negligible 49 0.133 Moderate 50 0.240 Severe 51 0.194 Moderate 52 0.204 Severe 53 0.132 Moderate 54 0.103 Moderate 55 0.093 Negligible 56 0.187 Moderate 57 0.089 Negligible 58 0.186 Moderate 59 0.132 Moderate 60 0.151 Moderate 504 -005.1 PLATE NO.� 77 HILLTOP GEOTECHNICAL, INC.-..- March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE W SULFATE EXPOSURE* Tract No. 31732 (Cont.) 61 0.124 Moderate 62 0.066 Negligible 63 0.043 Negligible 64 0.049 Negligible 64 0.067 Negligible 65 0.041 Negligible 65 0.061 Negligible 66 0.258 Severe 67 0.163 Moderate 68 0.051 Negligible 69 0.066 Negligible 70 0.253 Severe 71 0.102 Moderate 72 0.196 Moderate U 0.260 Severe 73 0.166 Moderate 74 0.112 Moderate 75 0.085 Negligible PLATE NO. 78 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA .,4 SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31732 (Cont.) 76 0.036 Negligible • 77 0.098 Negligible 78 0.099 Negligible 79 0.125 Moderate 80 0.117 Moderate 81 0.253 Severe 82 0.193 Moderate 83 0.132 Moderate 84 0.132 Moderate 85 0.106 Moderate 86 0.135 Moderate 87 0.104 Moderate 88 0.115 Moderate 89 0.146 Moderate 90 0.088 Negligible 91 ,0.104 Moderate 92 0.133 Moderate 93 0.151 Moderate 0 PLATE NO. 79 _ HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31732 (Cont.) 94 0.175 Moderate 95 0.204 Moderate 96 0.263 Severe 97 0.204 Severe 98 0.150 Moderate 99 0.044 Negligible 100 0.121 Moderate 101 0.225 Severe 102 0.195 Moderate 103 0.246 Severe 104 0.141 Moderate 105 0.085 Negligible 106 0.140 Moderate 107 0.121 Moderate 108 0.121 Moderate 109 0.132 Moderate 110 0.241 Severe 111 0.174 Moderate PLATE NO. 80 s HILLTOP GEOTECHNICAL, INC. i r • • • • March-8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31732 (Cont.) 112 0.135 Moderate 113 0.246 Severe 114 0.162 Moderate 115 0.249 Severe 116 0.216 Severe 117 0.174 Moderate 118 0.057 Negligible 119 0.029 Negligible 120 0.017. Negligible 121 0.012 Negligible 122 0.018 Negligible 123 0.019 Negligible 124 0.054 Negligible 125 0.055 Negligible 126 0.051 Negligible 127 0.053 Negligible 128 0.080 Negligible 129 0.103 Moderate 504 -005.1 PLATE NO. 81 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31732 (Cont.) 130 0.061 Negligible 131 0.130 Moderate 132 0.114 Moderate 133 0.162 Moderate 134 0.252 Severe 135 0.252 Severe 136 0.078 Negligible 137 0.079 Negligible 138 0.103 Moderate 139 0.055 Negligible 140 0.100 Moderate 141 0.102 Moderate 142 0.072 Negligible 143 0.083 Negligible 144 0.091 Negligible 145 0.079 Negligible 146 0.028 Negligible 147 0.095 Negligible PLATE NO. 82 91% HILLTOP GEOTECHNICAL, INC. March 8, 2007 SUM14ARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE W SULFATE EXPOSURE* Tract No. 31732 (Cont.) 148. 0.097 Negligible 149 0.029 Negligible 150 0.061 Negligible 151 0.048 Negligible 152 .0.040 Negligible 153 0.092 Negligible 154 0.174 Moderate 155 0.120 Moderate 156 0.142 Moderate 157 0.186 Moderate 158 0.120 Moderate 159 0.215 Severe 160 0.102 Moderate 161 0.156 Moderate 162 0.264 Severe 163 0.225 Severe 164 0.441 Severe 165 0.160 Moderate 504 =C05.1 PLATE NO. 83 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE ( %) SULFATE EXPOSURE* Tract No. 31732 (Cont.) 166 0.339 Severe 167 0.332 Severe 168 0.235 Severe 169 0.265 Severe 170 0.066 Negligible 170 0.070 Negligible 171 0.080 Negligible 172 0.066 Negligible 173 0.066 Negligible 174 0.144 Moderate 175 0.077 Negligible 176 0.085 Negligible 177 0.043 Negligible 178 0.256 Moderate 180 ** 0.072 Negligible 181 0.122 Moderate 182 0.052 Negligible 183 0.074 Negligible PLATE NO. 84 HILLTOP GEOTECHNICAL, INC. March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE ( %O) . SULFATE EXPOSURE* Tract No. 31732 (Cont.) 184 0.081 Negligible 185 0.097 Negligible 186, 0.072 Negligible 187 0.100 Moderate 188 0.377 Severe 189 0.335 Severe 190 0.368 Severe 191 0.555 Severe 192 0.357 Severe 193 0,271 Severe 194 0.155 Moderate 194 0.653 Severe 195 0.185 Moderate UU 0.140 Moderate * Per Table 19 -A -4, `Requirements for . Concrete Exposed to Sulfate- - Containing Solutions,' in the 2001 CBC. Lot Nos. 46 and 179 of Tract 31732 were not tested. 504 -005.1 PLATE NO. 85 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE'S Tract No. 31733 1 0.215 Severe 2 0.163 Moderate 3 0.174 Moderate 4 0.102 Moderate 5 0.084 Negligible 6 0.113 Moderate 7 0.074 Negligible 8 0.069 Negligible 9 0.071 Negligible 10 0.102 Moderate 11 0.107 Moderate 12 0.192 Moderate 13 0.099 Negligible 14 0.084 Negligible 15 0.079 Negligible 16 0.047 Negligible 17 0.050 Negligible 18 0.139 Moderate PLATE NO. 86 HILLTOP GEOTECHNICAL, INC. • • • • • • • • • • • i� • • March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31733 (Cont.) 19 0.109 Moderate 20 0.139 Moderate 21 0.042 Negligible 22 0.126 Moderate 23 0.033 Negligible 24 0.085 Negligible 25. 0.127 Moderate 25 0.036 Negligible 26 0.055 Negligible 27 0.039 Negligible 28 0.094 Negligible 29 0.044 Negligible 30 0.194 Moderate 31 0.076 Negligible 32 0.083 Negligible 33 0.111 Moderate 34 0.069 Negligible 35 0.067 Negligible PLATE NO. 87 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE ( %) SULFATE EXPOSURE* Tract No. 31733 (Cont.) 36 0.084 Negligible 37 0.172 Moderate 38 0.227 Severe 39 0.126 Moderate 40 0.047 Negligible 41 0.159 Moderate 42 0.178 Moderate 43 0.175 Moderate 44 0.121 Moderate 45 0.038 Negligible 46 0.135 Moderate 47 0.083 Negligible 48 0.173 Moderate F 0.086 Negligible F 0.090 Negligible 49 0.135 Moderate 50 0.224 Severe 51 0.115 Moderate PLATE NO. 88 HILLTOP GEOTECHNICAL, INC. March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE W SULFATE EXPOSURE* Tract No. 31733 (Cont.) 52 0.229 Severe 53 0.255 Severe 54 0.114 Moderate 55 0.110 Moderate 56 0.088 Negligible 57 0.145 Moderate 58 0.091 Negligible 59 0.151 Moderate 60 0.137 Moderate 61 0.044 Negligible 62 0.070 Negligible 63 0.236 Severe 64 0.095 Negligible 65 0.053 Negligible 66 0.091 Negligible 67 0.089 Negligible 68 0.126 Moderate 69 0.080 Negligible 504 -005.1 PLATE NO. 89 HILLTOP GEOTECHNICAL, INC. March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE M SULFATE EXPOSURE* Tract No. 31733 (Cont.) 70 0.031 Negligible 71 0.116 Moderate 72 0.210 Severe 73 0.094 Negligible 74 0.066 Negligible 75 0.104 Moderate 76 0.120 Moderate 77 0.156 Moderate 78 0.118 Moderate 79 0.140 Moderate 80 0174 Moderate 81 0.081 Negligible 82 0.151 Moderate 83 0.068 Negligible 84 0.086 Negligible 85 0.079 Negligible 86 0.249 Severe 87 0.117 Moderate PLATE NO. 90 HILLTOP GEOTECHNICAL, INC. March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS . (California Test 417) LOT NO. SOLUBLE SULFATE ( %) SULFATE EXPOSURE* Tract No. 31733 (Cont.) 88 0.152 Moderate 89 0.060 Negligible 90 0.121 Moderate 91 0.051 Negligible 92 0.124 Moderate 93 0.126 Moderate 94 0.095 Negligible 95 0.148 Moderate 96 0.199 Moderate 97 0.161 Moderate 98 0.124 Moderate 99 0.035 Negligible 100 0.059 Negligible 101 0.037 Negligible 102 0.099 Negligible 103 0.049 Negligible 104 0.054 Negligible 105 0.071. Negligible 504 -005.1 PLATE NO. 91 HILLTOP GEOTECHNICAL, INC. n r,: March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT NO. SOLUBLE SULFATE SULFATE EXPOSURE* Tract No. 31733 (Cont.) 106 0.028 Negligible 107 0.037 Negligible 108 0.027 Negligible 109 0.021 Negligible 110 0.014 Negligible 111 0.021 Negligible 112 0.034 Negligible 113 0.021 Negligible 114 0.032 Negligible 115 0.198 Moderate 116 0.138 Moderate 117 0.098 Negligible 118 0.120 Moderate 119 0.253 Severe 120 0.060 Negligible 121 0.119 Moderate 122 0.250 Severe 123 0.200 Severe . PLATE NO. 92 HILLTOP GEOTECHNICAL, INC. i r s March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE SULFATE TEST RESULTS (California Test 417) LOT SOLUBLE SULFATE NO. SULFATE EXPOSURE* Tract No. 31732 2 190 Tract No. 31733 (Cont.) 124 0.168 Moderate 125 0.145 Moderate Per Table 19 -A -4, `Requirements for Concrete Exposed to Sulfate - Containing Solutions,' in the 2001 CBC. * Lot Nos. 46 and 179 of Tract 31732 were not tested. SOLUBLE CHLORIDE TEST RESULTS (California Test 422) LOT SOLUBLE NO. CHLORIDE (PPM) Tract No. 31732 2 190 12 940 21 920 30 180 40 340 504 -005.1 PLATE NO. 93 t HILLTOP GEOTECHNICAL, INC. 0 March 8, 2007 504 -005.1 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE CHLORIDE TEST RESULTS (California Test 422) LOT NO. SOLUBLE CHLORIDE (PPm) Tract No. 31732 (Cont.) 50 2,210 60 2,380 70 490 78 310 90 430 102 1,030 110 2,570 117 1,230 127 250 137 360 147 1,040 157 1,130 165 1,250 170 770 180 250 195 260 PLATE NO. 94 HILLTOP GEOTECHNICAL, INC. March 8, 2007 SUMMARY OF LABORATORY TEST RESULTS TRACT NOS. 31732 AND 31733 CITY OF LA QUINTA, CA SOLUBLE CHLORIDE TEST RESULTS (California Test 422) LOT NO. SOLUBLE CHLORIDE (PPm) Tract No. 31733 4 330 13 530 19 370 27 130 35 440 48 1,750 51 930 65 250 70 160 79 920 97 560 107 290 118 380 504 -005.1 PLATE NO. 95 HILLTOP GEOTECHNICAL, INC. • • • • • ,r.„ "• • WI k p ,HILLTOP GEOTECHrTICAL, WC. 504 -A05.9 December 23, 2011 Page B -1 TECHNICAL REFERENCES Abrahamson, N.A. and Silva, W.J., 1996, Technical Notes to Brookhaven National. Laboratory (Unpublished). American Society of Civil Engineers, 2006, Minimum Design. Loads for Buildings and Other Structures: ASCE Standard No. 7 -05, Revised ASCE /SEI 7- 07, including Supplement No. 1 and Errata. Blake, Thomas F., 2000, Preliminary Fault -Data for EQFAULT, EQSEARCHand FRISKSP. Blake, Thomas, F., Computer Services and Software, Users Manuals, FRISKSP v. 4.00, EQSEARCH v. 3.00, and EQFAULT v. 3.00. Boore, David M., Joyner, William B., and Fumal, Thomas E., January / February 1997, Spectra and Peak Acceleration from Western North American Earthquakes: a Summary ofRecent Work: Seismological Research Letters, Volume 68, Number 1. Bray, J.D., 1998, Arias Duration of Strong Shaking Attenuation: Presented in Evaluation and Mitigation of Seismic Hazards: University of California, Berkeley, Continuing Education in Engineering, August 1998. California Building Standards Commission, Effective January 1, 2011, 2010 California Building Code: California Code of Regulations, Title 24, Part 2, Volume 1 of 2 and Volume 2 of 2 (Based on 2009 International Building Code). California Department of Conservation, Division of Mines and Geology, Geomorphic Provinces and Some Principal Faults of California: CDMG Note 86. California Department of Conservation, Division of Mines and Geology, 1986, Guidelines for Evaluating the Hazard of Surface Fault Rupture: CDMGNete 41. California Department of Conservation, Division of Mines and Geology, Guidelines to Geologic /Seismic Reports: CDMG Note 42. HILLTOP GEOTECBMCAL, INC. 504 -A05.9 December 23, 2011 Page B -2 TECHNICAL REFERENCES - California Department of Conservation, Division of Mines and Geology, Guidelines for Preparing Engineering Geologic Reports: CDMG Note 44. California Department of Conservation, Division of Mines and Geology, 1976 (Revision September 1983), Guidelines for Evaluating the Hazard of Surface Fault Rupture: CDMG Note 49. California Department of Conservation, California Geological Survey, Interim Revision 2007, Fault - Rupture Hazard Zones in California, Alquist- Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zones?Maps, (!Name Changed from `Special Studies Zones,' January 1,1994.): Special Publication 42. California Department" of Conservation, Division of Mines and Geology, 1982, Earthquake Planning Scenario for a Magnitude 8.3 Earthquake on the San Andreas Fault in Southern California: Special Publication 60. California Department of Conservation, Division of Mines and Geology, 2008, Guidelines for Evaluating and Mitigating Seismic Hazards in California: Special Publication 117A. California Department of Conservation, Division of Mines and Geology, 1982, Geology of the NE San Bernardino Mountains, San Bernardino County, California: CDMG Open -File Report 82 -18. California Department of Conservation, Division of Mines and Geology, 1990, Index to Fault Evaluation Reports Prepared 1976 -1989 Under the Alquist- Priolo Special Studies Zone Act: CDMG Open -File Report 90 -9. California Department of Conservation, Division of Mines and Geology, 1996 (Appendix A - Revised 2002), Probabilistic Seismic Hazard Assessment for the State of California: CDMG Open -File Report 96 -08. California Department of Conservation, Division of Mines and Geology, 1992, Quick Report on CSMIP Strong- Motion Records from the June 28, 1992 Earthquakes Near Landers and Big Bear, California: CSMIP Report OSMS 92 -06. HILLTOP GEOTECHNICAL, INC. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page B -3 r - TECHNICAL REFERENCES California Department of Conservation, Division of Mines and Geology, 1994, CSMIP Strong - Motion Records from the Northridge; California Earthquake w of January 17,1994: CSMIP Report OSMS 94 -07. California Department of Conservation, Division of Mines and Geology, 1994, Jennings, C.W., Fault Activity Map of California and Adjacent Areas with • Locations and Ages of Recent Volcanic Eruptions: Geologic Data Map No. 6, Scale: 1:750,000. 0 0 California Department of Conservation, Division of Mines and Geology, 0 November 1992, Future Seismic Hazards in Southern California, Phae L • Implications of the 1992 Landers Earthquake Sequence. 0 California Department of Conservation, Division of Mines and Geology, 0 1999, Seismic Shaking Hazard Maps of California: Map Sheet 48. 0 Campbell, K.W. and Bozorgnia, Y., 1994, Near - Source Attenuation of Peak 0 Horizontal Acceleration from Worldwide Accelerograms Recorded from 1957 to 0 1993: Fifth U.S. National Conference on Earthquake Engineering Proceedings, 0 Vol. III, pp. 283 -292. CivilTech Software, 2006, LiquefyPro, Liquefaction and .Settlement Analysis, w Software Manual, Version 5 and Later. 0 0 Committee on Earthquake Engineering, Commission on Engineering and Technical Systems, National Research Council, 1985, Liquefaction of Soils 0 During Earthquakes. 0 0 Earthquake Engineering Research Institute, July 10 -14, 1994, Earthquake • Awareness and Mitigation Across the Nation Proceedings, Volume III: Fifth U.S. National Conference on Earthquake Engineering, Chicago, Illinois. 0 0 Frankel, A., Harmeson, S., Mueller, C., Barnhard, Y., Leyendecker, E.V., • Perkins, D., Hanson, S., Dickman, N., and Hopper, M., 1997, Uniform Hazard Spectra, Deaggregation, and Uncertainty: Proceedings of FHWA/NCEER Workshop on the National Representation of Seismic Ground Motion for New and 0 Existing Highway Facilities: NCEER Technical Report 9700010, pp. 39 -73 [Text HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page B -4 TECHNICAL REFERENCES to accompany gridded values for the California probabilistic seismic hazard model, downloadable data athttp:// www. geohazards. cr. usgs.gov /eq /data/CNUmaplr.asc]. Harden, D.R., 1997, California Geology: Prentice Hall. Idriss, I.M., Principal, Evaluating Seismic Risk in Engineering Practice: Woodward -Clyde Consultants, Santa Ana California, and Adjunct Professor of Civil Engineering, University of California, Los Angeles, USA. International Conference of Building Officials, February 1988, Maps of Known Active Fault Near - Source Zones in California and Adjacent Portions of Nevada, To be used with the 1997 Uniform Building Code: Prepared by California Department of Conservation, Division of Mines and Geology in cooperation with Structural Engineers Association of California Seismology Committee. Ishihara, K., 1985, Stability of Natural Deposits During Earthquakes: Proceedings: 11th International Conference on Soil Mechanics and Foundation Engineering, San Francisco, Vol. 1. pp. 321 -376. Ishihara, K., 1993, Liquefaction and Flow Failures During Earthquakes: Geotechnique, Vol.43, No. 3, pp. 351 -415. Lew, M., Hudson, M.B., Acosta, J.A., of MACTEC Engineering and Consulting, Inc., and Elhassan, R.E., of Integrated Design Services, Inc. Structural Engineers, Undated, White Paper on Seismic Increment of Active Earth Pressure: 12 p. Liao, S.S.C. and Whitman, R.V., 1986, Overburden Correction Factors for SPT in Sand: Journal of Geotechnical Engineering, ASCE, Vol. 112, No. 3, pp. 373 -377. Matti, J.C. and Morton, D.M., 1993, Paleogeographic Evolution of the San Andreas Fault in Southern California: a Reconstruction Based on a New Cross-fault Correlation, in the San Andreas Fault System: Displacement, Palinspastic Reconstruction and Geologic Evolution, Edited by R.E. Powell, R.J. Weldon, and J.C. Matti, Mem. Geologic Society of America, Bulletin 178, pp. 107 -160. HILLTOP GEOTECHNICAL, INC. S 504 -A05.9 December 23, 2011 Page B-5 TECHNICAL REFERENCES Meisling, K.E. and Weldon, R.J., 1989, Late Cenozoic Tectonics of the Northwestern San Bernardino Mountains, Southern Ca.: Geologic Society of America, Bulletin 101, pp. 106 -128. Moriwaki, Yoshiharu, 1991, Earthquake Hazard Evaluation and Site Response Analyses, Seismic Short Course, Evaluation and Mitigation of Earthquake Induced Liquefaction Hazards: San Francisco State University, Division of Engineering, San Francisco, January 28 & 29, 1991, University of Southern California, School of Engineering, Department of Civil Engineering, Los Angeles, February 4 & 5. Navel Facilities Engineering Command, September 1986, Foundations & Earth Structures: Design Manual 7.02, Change 1. Post - Tensioning Institute, 1996 (Second Edition), Design and Construction of Post - Tensioned Slabs -on- Ground. Post - Tensioning Institute, 2004 (Third Edition) with Addendum 1 dated May 2007 and Addendum 2 dated May 2008, Design o f Post - Tensioned Slabs -on- Ground. Pradel, D., 1998, Procedures to Evaluate Earthquake- Induced Settlement in Dry Sandy Soils: ASCE Geotechnical Journal, April 1998, pp. 364 -368. Riverside County Land Information System website (www3.tlma.co.riverside.ca.us/pa/rclis/`*ndex.html). Robertson, P.K. and Wride, C.E., 1997, Cyclic Liquefaction and its Evaluation Based on the SPT and CPT: Proc. NCEER Workshop on Evaluation of Liquefaction Resistance of Soils, Youd, T.L., and Idriss, I.M., Technical Report NCEER 97 -0022, pp. 41 -48. Seeber, L. and Armbruster, J.G., 1995, The San Andreas Fault System Through the Transverse Ranges as Illuminated by Earthquakes Abstract, J. Geophys. Res., 100, 8285. Seed, H.B., 1996, Recent Advances in Evaluation and Mitigation of Liquefaction Hazards: Ground Stabilization and Seismic Mitigation, Theory . and Practice, Oregon, Nov. 6 and 7, 1996. HILLTOP GEOTECHNICAL, INC. N 504 -A05.9 December 23, 2011 Page B -6 TECHNICAL REFERENCES Seed, H.B. and Idriss, I.M., 1971, Simplified Procedure for Evaluating Soil Liquefaction Potential: Journal of Soil Mechanics and Foundation Division, ASCE, Vol. 97, No. SM9; pp. 1249 -1274, September 1971. Seed, H.B. and Idriss, I.M., 1982, Ground Motions and Soil Liquefaction During Earthquakes: Earthquake Engineering Research Institute, Berkeley, California, 134 p. South Coast Geological Society, Inc., 1989, San Andreas Fault, Cajon Pass to Wallace Creek: Guidebook Number 17, Volumes 1 and 2. Southern California Earthquake Center, March 1999, Recommended Procedures for Implementation of DMG Special Publication 117, Guidelines for Analyzing and Mitigating Liquefaction Hazards in California. Southern California Earthquake Center, June 2002, Recommended Procedures for Implementation ofDMG Special Publication 117, Guidelines for Analyzing and Mitigating Landslide Hazards in California. . Tokimatsu, K. and Seed, H.B., 1987, Evaluation of Settlements in Sands Due to Earthquake Shaking: Journal of Geotechnical Engineering Division, ASCE, Volume 113, No. 8, August, pp.861 -878. U.S. Department of the Interior, U.S. Geological Survey, 1987, Recent Reverse Faulting in the Transverse Ranges, California: Text and Plates, U.S. Geological Survey Professional Paper 1339. U.S. Department of the Interior, U.S. Geological Survey, 1985, Evaluating Earthquake Hazards in the Los Angeles Region -An Earth - Science Perspective: U.S. Geological Survey Professional Paper 1360. U.S. Department of the Interior, U.S. Geological Survey, 1985, Matti, J.C., Morton, D.M., and Cox, B.F., Distribution and Geologic Relations of Fault Systems in the Vicinity of the Central Transverse Ranges, Southern California: U.S. Geological Survey Open -File Report 85 -365. HILLTOP GEOTECHNICAL, INC. 504 -A05.9 December 23, 2011 Page B -7 TECHNICAL REFERENCES U.S. Department of the Interior, U.S. Geological Survey, 2002, Interactive Deaggregations: ( http: // equint. cr .usgs.gov /deaggint/index.php). U.S. Department of the Interior, U.S. Geological Survey, 1956, Photorevised 1972, Valerie Quadrangle, California - Riverside Co., 7.5- Minute Series (Topographic), Scale: 1:24,000. U.S. Federal Emergency Management Administration (FEMA), Effective August 28, 2008, Flood Insurance Rate Map, Map No.: 06065C2925G G. Site specific information obtained through FEMA website, Map Service Center, • (http: / /msc'fema.gov/). Weldon, R.J., and Sieh, K.E., 1985, Holocene Rate of Slip and Tentative Recurrence Interval for Large Earthquakes on the SanAndreas Fault in Cajon Pass, Southern California: Geological Society of America Bulletin 96, pp. 793 -812. Wesnousky, Steven G., Prentice, Carol S., and Sieh, Kerry E., 1991, An Offset Holocene Stream Channel and the Rate of Slip along the Northern Reach of the San Jacinto Fault Zone, San Bernardino Valley, California: Geological Society of America Bulletin, V 103. Youd, T.L. and Idriss, I.M. (Editors), 1997, Proceedings of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils: Salt Lake City, UT, January 5 -6, 1996, Technical Report NCEER -97 -0022, 307 p., Buffalo, NY. HILLTOP GEOTECHNICAL, INC. Liquefaction Analysis Tentative Tract Map 36305 Hole No. =B -4 Water Depth =24 tt Shear Stress Ratio Factor of Safety Settlement Soil Description (tt)0 0 1 0 1 5 0 (in.) 10 —10 I— 20 1— 30 1— 40 I- 60 1MIECO Brown, Brown, Magnitude =7.76 Acceleration =0.60g Raw Unit Fines SPT Weight Brown, fine, sandy silt Olive- brown, clayey, fine sand Brown, silty, fine sand brown To gray, spry, Tine sana Brown to gray, silty, fine sand to olive- brown, fine, sandy clay Gray, slightly silt, fine to coarse sand Gray, slightly silty, fine to coarse sand CRR — CSR fs1-- Wet— Dry— Shaded Zone has Liquefaction Potential S = 5.49 in. 5 10 .876 12 99.2 76 8 99.2 26 11 123.183 18 114.320 17 115.023 8 105.046 3 105.046 11 137.735 4 128.588 6 125.437 20 131.710 20 131.79 504 -A05.9 Plate C -1 a u. a u t C f 0 a Liquefaction Analysis Tentative Tract Map 36305 Hole No. =B -4 Water Depth =5.0 ft Shear Stress Ratio Factor of Safety Settlement 0 1 0 1 5 0 (in.) 10 (ftI0 iU] F— 20 1— 30 I— 40 I— 50 Shaded Zone has Liquefaction Potentlal 1-60 70 ..,..�.� Wet— D, S = 8.18 in. Soil Description Magnitude =7.76 Acceleration =0.60g Raw Unit Fines SPT Weight 5 109 876 504 -A05.9 12 99.2 76 8 99.2 26 11 123.183 18 114.320 17 115.023 8 105.046 3 105.046 11 137.735 6 125.437 20 131.710 20 131.79 Plate C -2 Brown, fine, sandy silt Brown, fine, sandy silt ul Brown, silty, fine sand Brown, fine, sandy silt Olive- brown, clayey, fine sand Brown, silty, fine sand TTI Brown to gray, silty, fine sand Brown to gray, silty, fine sand Brown, silty, fine to medium sand Gray to olive- brown, fine, sandy clay Gray, silty, fine sand Gray, slightly silt, fine to coarse sand Gray, slightly silty, fine to coarse sand 504 -A05.9 12 99.2 76 8 99.2 26 11 123.183 18 114.320 17 115.023 8 105.046 3 105.046 11 137.735 6 125.437 20 131.710 20 131.79 Plate C -2 t a a a t� 'c 0 .i e Dry Sand Settlement Analysis Tentative Tract Map 36305 Hole No. =B -4 Water Depth =24.0 ft Magnitude =7.76 Shear Stress Ratio Factor o' Safety Settlement 0 1 0 1 5 0 (in.) 10 (n)0 10 F— 20 I— 30 i— 40 i— 50 F-- 60 70 Shaded Zone has Liquefaction Potential Wet— Dry- S = 9.86 in. Acceleration =O.60g Soil Description Raw Unit Fines SPT Wetght % 5 10J 876 504 -AO5.9 12 99.2 76 8 99.2 26 11 123.183 18 114.320 17 115.023 8 105.046 3 105.046 11 137.735 4 128.588 6 125.437 20 131.710 20 131.79 Plate C -3 Brown, fine, sandy silt Brown, fine, sandy silt Brown, silty, fine sand Brown, fine, sandy silt Oiive- brown, clayey, fine sand Brown, silty, fine sand Brown to gray, silty, fine sand Brown to gray, silty, fine sand Brown, silty, fine to medium sand Gray to olive- brown, fine, sandy clay Gray, silty, fine sand Gray, slightly silt, fine to coarse sand Gray, slightly silty, fine to coarse sand 504 -AO5.9 12 99.2 76 8 99.2 26 11 123.183 18 114.320 17 115.023 8 105.046 3 105.046 11 137.735 4 128.588 6 125.437 20 131.710 20 131.79 Plate C -3 APPENDIX C HILLTOP GEOTECHNICAL, INC. UtTlumWay 110L= lcvbdw wau"0002 SOM c-91 mlm�. =.% 9 XOZF�- - - mm R l�arcaiaftn 'UlLocMor simian w Am VA* 120 1 L2tia 904A06.10 ruew f 4PAOMSC" ax Uo" C777777-73 -A� m p k" a SITE PLAN SITE DEVELOPMENT PERMIT 2011.918 Renditions at Palizada TENTATIVE TRACT MAP NO. 36305 PrfOCLIQW& COW, C2 SDP 2011-918 SHEET 3 -j� 4 AWE R l�arcaiaftn 'UlLocMor simian w Am VA* 120 1 L2tia 904A06.10 ruew f 4PAOMSC" ax Uo" C777777-73 -A� m p k" a SITE PLAN SITE DEVELOPMENT PERMIT 2011.918 Renditions at Palizada TENTATIVE TRACT MAP NO. 36305 PrfOCLIQW& COW, C2 SDP 2011-918 SHEET 3 INFILTROMETER TEST. P -1 DATE OF TEST . 40896.0 DEPTH OF PROJECT IDENTIFICATION: 504- A05.10 Palizada Infiltrometer AREA(CM2) LIQUID (CM) TEST LOCATION: Bottom of Proposed Basin, 77' INNER 699.6 INNER 15.24 LIQUID USED: Municipal H2O OUTER 2128.5 r: OUTER 15.24 TESTED BY: KB LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) DEPTH TO WATER TABLE: N/A INNER RING AVERAGE RATE 1.1. nI ITFR RING, AVFRAGF RATE 1.2 Increment No. DATE TIME START= 11:04 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 61F . @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER CM /H I ANNULAR CM /H 1 December 19th 2011 11:19 15 500 1,670 62 2.9 1 3.1 165, Sunny 2 December 19th 2011 11:34 15 470 1,500 62 2.7 2.8 165,Sunny 3 December 19th 2011 11:49 15 410 800 1 63 2.3 1.5 165,Sunny 4 December 19th 2011 12:04 15 300 900 64 1 1.7 1 1.7 166,Sunny 5 December 19th 2011 12:34 30 240 1,220 64 0.7 1.1 66, Sunny 6 December 19th 2011 13:04 �30 330 1,250 64 0.9 1.2 167, Slight Breeze, High Clouds 7 December 19th 2011 14:04 60 420 1,440 65 0.6 0.7 68, Slight Breeze, High Clouds 8 December 19th 2011 15:04 60 300 1,300 65 1 0.4 1 0.6 16.5, Slight Breeze, High Clouds 9 December 19th 2011 16:04 60 320 1,000 64 0.5 0.5 61, Slight Breeze, High Clouds F'o-1December 19th 2011 17:04 60 320 1,000 63 0.5 0.5 56, Slight Breeze, High Clouds r INFILTROMETER TEST P -1 504- A05.10' HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO. 2 INFILTROMETER TEST PROJECT IDENTIFICATION: TEST LOCATION: LIQUID USED: Municipal H2O TESTED BY: KB DEPTH TO WATER TABLE:. P -2 DATE OF TEST 40896.0 DEPTH OF 504- A05.10 La Quinta Infiltrometer AREA(CM2) LIQUID (CM) Bottom of Proposed Basin, 5'6" INNER 699.6 INNER 15.24 OUTER 2128.5 OUTER 15.24 LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) N/A INNER RING AVERAGE RATE 0.6 n1 ITFR RINr. AVFRAr;F RATF 2.2 Increment No. DATE TIME START= 11:45 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 61 F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER CM /H ANNULAR CM /H 1 December 19th 2011 12:00 15 300 2,520 64 1.7 4.7 165, Sunny 2 December 19th 2011 12:15 15 200 1,900 64 1.1 1 3.6 166,Sunny 3 December 19th 2011 12:30 15 190 1,510 65 1.1 1 2.8 66, Sunny 4 December 19th 2011 12:45 15 150 1,000 65 0.9 1 1.9 167,Sunny 5 December 19th 2011 13:15 30 180 2,360 66 0.5 2.2 167, Slight Breeze, High Clouds 6 December 19th 2011 13:45 30 180 2,260 66 0.5 2.1 168, Slight Breeze, High Clouds 7 December 19th 2011 14A T-60 300 4,000 66 0.4 1.9 66, Slight Breeze, High Clouds 8 December 19th 2.011 15:45 60 300 4,000 64 0.4 1.9 62, Slight Breeze, High Clouds 9 December 19th 2011 16:45 60 300 4,000 64 0.4 1.9 57, Slight Breeze, High Clouds 10 December 19th 2011 17:45 60 300 3,300 62. 0.4 1.6 52, Slight Breeze, High Clouds INFILTROMETER TEST P -2 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO. 3 INFILTROMETER TEST P -3 DATE OF TEST 40897.0 DEPTH OF PROJECT IDENTIFICATION: 504- A05.10 Palizada Infiltrometer AREA(CM2) LIQUID (CM) TEST LOCATION: Bottom of Proposed Basin, 8'1" INNER 699.6 INNER 15.24 LIQUID USED: Municipal H2O OUTER 2128.5 OUTER 15.24 TESTED BY KB LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) DEPTH TO WATER TABLE: N/A INNER RING AVERAGE RATE 0.0 OUTER RING AVERAGE RATE 0.1 Increment No. DATE TIME START= 09:53 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 55 F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER CM /H ANNULAR CM /H 1 December 20th 2011 10:08 15 0 50 61 0.0 0.1 63, Sunny 2 December 20th 2011 10:23 15 0 50 60 0.0 0.1 63, Sunny 3 December 20th 2011 10:38 15 0 50 60 0.0 0.1 66, Sunny, Slight Breeze 4 December 20th 2011 10:53 15 0 50 60 0.0 0.1 67, Sunny, Slightly Breezy 5 December 20th 2011 11:23 30 0 100 61 0.0. 1 0.1 168, Slight Breeze, High Clouds 6 December 20th 2011 11:53 30 0 100 60 0.0 1 0.1 169, Slight Breeze, High Clouds 7 December 20th 2011 12:53 60 0 150 63 0.0 0.1 72, Slight Breeze, High Clouds 8 December 20th 2011 13:53 60 0 150 61 0.0 0.1 71, Slight Breeze, High Clouds 9 December 20th 2011 14:53 60 0 150 61 0.0 0.1 68, Slight Breeze, High Clouds 10 December 20th 2011 15:53 60 0 150 60 0.0 0.1 67, Slight Breeze, High Clouds INFILTROMETER TEST P -3 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO.4 INFILTROMETER TEST PROJECT IDENTIFICATION: TEST LOCATION: LIQUID USED: Municipal H2O TESTED BY: KB DEPTH TO WATER TABLE: P-4 DATE OF TEST 40897.0 DEPTH OF 504- A05.10 Palizada Infiltrometer AREA(CM2) LIQUID (CM) Bottom of Proposed Basin, 4'6" INNER 699.6 INNER 15.24 OUTER 2128.5 OUTER 15.24 LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) N/A INNER RING AVERAGE RATE 9.1 (ll ITFR RINr, AVFRArF= RATF .10.0 Increment No. DATE TIME START= 10:00 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 62.F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER I CM /H ANNULAR CM /H 1 December 20th 2011 10:15 15 2,150 8,000 60 12.3 1 15.0 163, Sunny 2 December 20th 2011 10:30 15 1,800 5,400 60 10.3 10.1 64, Sunny 3 December 20th 2011 10:45 15 1,900 5,400 60 10.9 10.1 167, Sunny, Slight Breeze 4 December 20th 2011 11:00 15 1,470 5,500 60 8.4 10.3 167, Sunny, Slightly Breezy 5 December 20th 2011 11:30 30 3,300 10,700 62 9.4 10.1 169, Slight Breeze, High Clouds 6 December 20th 2011 12:00 30 2,900 9,850 62 8.3 9.3 70, Slight Breeze, High Clouds 7 December 20th 2011 13:00 60 6,250 —F�22,000 65 8.9 10.3 172, Slight Breeze, High Clouds 8 December 20th 2011 14:00 60 5,900 20,550 66 8.4 9.7 170, Slight Breeze, High Clouds 9 December 20th 2011 15:00 60 6,000 21,000 68 8.6 9.9 169, Slight Breeze, High Clouds 10 December 20th 2011 16:00 60 5,900 21,000 67 8.4 9.9 62, Slight Breeze, High Clouds INFILTROMETER TEST P -4 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO. 5 INFILTROMETER TEST P -5 DATE OF TEST 40898.0 DEPTH OF PROJECT IDENTIFICATION: 504- A05.10 Palizada Infiltrometer AREA(CM2) LIQUID (CM) TEST LOCATION: Bottom of Proposed Basin, 4'6" INNER 699.6 INNER 15.24 LIQUID USED: Municipal H2O OUTER 2128.5 OUTER 15.24 TESTED BY: AH LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) DEPTH TO WATER TABLE: N/A INNER RING AVERAGE RATE 4.1 0HTFR RING AVERAGE RATE 6.4 Increment No. 'DATE TIME START= 09:47 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 69 F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER CM /H. ANNULAR CM /H 1 December 21 st 2011 10:02 15 2,000 8,000 58 11.4 1 15.0 169, Sunny 2 December 21st 2011 10:17 15 800 4,000 57 4.6 1 7.5 172,Sunny 3 December 21st 2011 10:32 15 770 3,810 57 4.4 7.2 176,Sunny 4 December 21st 2011 10:47 15 650 3,550 57 3.7 1 6.7 178, Sunny 5 December 21st 2011 11:17 30 1,370 7,000 55 3.9 6.6 85, Sunny, Slight Breeze 6 December 21st 2011 11:47 30 1,460 6,470 60 4.2 6.1 84, Sunny, Slight Breeze 7 December 21st 2011 12:47 60 2,610 12,700 69 3.7 6.0 180, Sunny, Slight Breeze 8 1 December 21st 2011 13:47 60 2,800 12,500 68 4.0 5.9 74, Sunny, Slight Breeze 9 December 21 st 2011 14:47 60 2,830 12,600 67 4.0 5.9 170, Slight Breeze, High Clouds 10 December 21st 2011 15:47 60 3,000 12,640 1 67 4.3 1 5.9 167, Slight Breeze, High Clouds I 7 INFILTROMETER TEST P -5 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO. 6 INFILTROMETER TEST PROJECT IDENTIFICATION: TEST LOCATION: LIQUID USED: Municipal H2O TESTED BY: AH DEPTH TO WATER TABLE: P -6 DATE OF TEST 40898.0 DEPTH OF 504- A05.10 Palizada Infiltrometer AREA(CM2) LIQUID (CM) Bottom of Proposed Basin, 1'25" INNER 699.6 INNER 15.24 OUTER 2128.5 OUTER 15.24 LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) N/A INNER RING AVERAGE RATE 0.8 01 ITFR PIN(-, AVFRAC,F RATF 1.9 Increment No. DATE TIME START= 09:58 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 62 F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER CM /H ANNULAR CM /H 1 December 21st 2011 10:13 15 0 1,000 56 0'0 1.9 172, Sunny 2 December 21st 2011 10:28 15 260 1,550 58 1.5 2.9 75, Sunny 3 December 21st 2011 10:43 15 0 1,000 60 0.0 1.9 178,Sunny 4 December 21st 2011 10:58 15 280 1,000 60 1.6 1.9 178,Sunny 5 December 21st 2011 11:28 30 290 1,570 60 0.8 1.5 182, Sunny, Slight Breeze 6 December 21st 2011 11:58 30 210 1,700 65 0.6 1.6 86, Sunny, Slight Breeze 7 December 21st 2011 12:58 60 500 3,770 67 0.7 1.8 179, Sunny, Slight Breeze 8 December 21st 2011 13:58 60 500 3,670 67 0.7 1.7 178, Sunny, Slight Breeze 9 December 21st 2011 14:58 60 510 3,640 70 0.7 1.7 74, Sunny, Slight Breeze 10 December 21st 2011 15:58 60 530 4,660T 67 0.8 1 1.9 171, Sunny, Slight Breeze INFILTROMETER TEST P -6 . 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO. 7 0 0 0 0 0 0 0 0 0 0 0 0 * 0 0 0 0 0 0 0 ` 0 0 0 , .0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o o INFILTROMETER TEST P -7 DATE OF TEST 12/22/11 DEPTH OF PROJECT IDENTIFICATION: 504- A05.10 Palizada Infiltrometer AREA(CM2) LIQUID (CM) TEST LOCATION: Bottom of Proposed Basin, 1'8" INNER 699.6 INNER 15.24 LIQUID USED: Municipal H2O OUTER 2128.5 OUTER 15.24 TESTED BY KB LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) DEPTH TO WATER TABLE: N/A INNER RING AVERAGE RATE 0.4 nl ITFR RING AVFRAr.F RATE 0.5 Increment No. DATE TIME START= 09:24 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 56F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER CM /H ANNULAR CM /H 1 December 22nd 2011 9:39 15 200 0 58 1.1 0.0 64, Sunny, Breezy 2 December 22nd 2011 9:54 1 15 100 550 58 0.6 1 1.0 165, Sunny, Breezy 3 December 22nd 2011 10:09 15 100 350 58 0.6 0.7 166, Sunny, Breezy 4 December 22nd 2011 10:24 15 100 250 58 0.6 0.5 66, Sunny, Windy 5 December 22nd 2011 10:54 30 170 300 58 0.5 0.3 67, Sunny, Windy 6 December 22nd 2011 11:24 30 100 600 60 1 0.3 1 0.6 167, Sunny, Windy 7 December 22nd 2011 12:24 60 200 800 64 0.3 0.4 68, Sunny, Windy 8 December 22nd 2011 12:24 60 150 400 66 0.2 1 0.2 167, Sunny, Windy 9 December 22nd 2011 14:24 60 100 550 63 0.1 0.3 64, Sunny, Windy 10 December 22nd 2011 15:24 1 60 150 500 62 0.2 0.2 63, Sunny, Windy INFILTROMETER TEST P -7 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO. 8 INFILTROMETER TEST PROJECT IDENTIFICATION: TEST LOCATION: LIQUID USED: Municipal H2O TESTED BY: KB DEPTH TO WATER TABLE: P -8 DATE OF TEST 12/22/11 DEPTH OF 504- A05.10 Palizada Infiltrometer AREA(CM2) LIQUID (CM) Bottom of Proposed Basin, 38" INNER 699.6 INNER 15.24 OUTER 2128.5 OUTER 15.24 LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) N/A INNER RING AVERAGE RATE 4.5 ni JTFR Rwr, AVFRAGF RATE 8.0 Increment No. DATE TIME START= 09:31 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 56 F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER I CM /H ANNULAR CM /H 1 December 22nd 2011 9:46 15 2,350 9,000 59 13.4 1 16.9 162, Sunny, Breezy 2 1 December 22nd 2011 10:01 15 1,200 5,600 59 6.9 1 10.5 163, Sunny, Breezy 3 1 December 22nd 2011 11:31 15 1,000 4,400 59 5.7 8.3 63, Sunny, Breezy 4 December 22nd 2011 11:01 15 900 4,600 59 5.1 8.6 63, Sunny, Windy 5 December 22nd 2011 11:31 30 1,600 9,000 60 4.6 1 8.5 163, Sunny, Windy 6 December 22nd 2011 12:31 30 1,400 8,400 60 4.0 7.9 63, Sunny, Windy 7 IDecember 22nd 2011 13:31 60 2,700 16,000 60 3.9 7.5 64, Sunny, Windy 8 December 22nd 2011 13:31 60 2,500 15,000 63 3.6 1 7.0 164, Sunny, Windy 9 December 22nd 2011 14:31 60 2,400 15,000 63 3.4 7.0 64, Sunny, Windy 10 December 22nd 2011 15:31 60 2,400 14,000 62 3.4 6.6 161, Sunny, Windy INFILTROMETER TEST P -8 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO. 9 INFILTROMETER TEST P -9 DATE OF TEST 12/27/11 DEPTH OF PROJECT IDENTIFICATION: 504- A05.10 Palizada Infiltrometer. AREA(CM2) LIQUID (CM) TEST LOCATION: Bottom of Proposed Basin, 2'5" INNER 699.6 INNER 15.24 LIQUID USED: Municipal H2O OUTER 2128.5 OUTER 15.24 TESTED BY AH LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS ,(VISUAL) DEPTH TO WATER TABLE: N/A INNER RING AVERAGE RATE 0.6 OUTER RING AVERAGE RATE 1.1 Increment No. DATE TIME START= 09:58 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 68F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER. INNER FLOW CM3 OUTER FLOW CM3 INNER CM /H I ANNULAR CM /H 1 December 27th 2011 10:13 15 200 1,580 1 58 1.1 1 3.0 168, Sunny, Clear 2 December 27th 2011 10:28 15 140 880 58 0.8 1.7 175, Sunny, Clear 3 1 December 27th 2011 10:43 15 120 770 61 0.7 1.4 72, Sunny, Clear 4 December 27th 2011 10:58 15 140 650 60 0.8 1.2 73, Sunny, Clear 5 December 27th 2011 11:28 30 280 1,000 65 0.8 0.9 180, Sunny, Clear 6 December 27th 2011 11:58 30 230 1,000 63 0.7 1 0.9 185, Sunny, Clear 7 December 27th 2011 12:58 60 260 1,680 64 0.4 0.8 85, Sunny, Clear ? 8 December 27th 2011 13:58 60 300 2,000 68 0.4 0.9 83, Sunny, High Clouds 9 December 27th 2011 14:58 60 250 1,560 70 0.4 0.7 81, Sunny, High Clouds 10 December 27th 2011 15:58 60 290 1,830 67 0.4 0.9 64, Sunny, High Clouds INFILTROMETER TEST P -9 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA PLATE NO. 10 INFILTROMETER TEST PROJECT IDENTIFICATION: TEST LOCATION: LIQUID USED: Municipal H2O TESTED BY AH DEPTH TO WATER TABLE: P -10 DATE OF TEST 12/27/11 DEPTH OF 504- A05.10 Palizada Infiltrometer AREA(CM2) LIQUID (CM) Bottom of Proposed Basin, 2'0" INNER 699.6 INNER 15.24 OUTER 2128.5 OUTER 15.24 LIQUID LEVEL MAINTAINED USING: _X_ MANUAL ADDITIONS (VISUAL) N/A INNER RING AVERAGE RATE 0.4 nl 1TFR RIN(.' AVFRA(.F RATF 0.6 Increment No. DATE TIME START= 10:06 AM HR: MM ELAPSED TIME/ INCREMENT MIN FLOW READINGS LIQUID TEMP. F INCREMENTAL INFILTRATION RATE GROUND TEMP = 70 F @ DEPTH OF 12 INCHES AIR TEMP, WEATHER INNER FLOW CM3 OUTER FLOW CM3 INNER CM /H ANNULAR CM /H 1 December 27th 2011 10:21 15 460 1,390 58 1 2.6 2.6. 172, Sunny, Clear 2 December 27th 2011 10:36 15 260 590 60 1.5 1.1' 79, Sunny, Clear 3 December 27th 2011 10:51 15 110 430 60 0.6 0.8 178, Sunny, Clear 4 December 27th 2011 11:06 15 100 360 64 0.6 0.7 178, Sunny, Clear 5 I' December 27th 2011 11:36 30 110 820 65 0.3 0.8 76, Sunny, Clear I 6 I December 27th 2011 12:06 30 100 440 64 0.3 -F 0.4 175, Sunny, Clear 7 December 27th 2011 13:06 60 110 1,000 67 0.2 0.5 82, Sunny, Clear 8 December 27th 2011 14:06 60 120 1,000_ 69 0.2 0.5 187, Sunny, High Clouds 9 December 27th 2011 15:06 60 120 1,000 68 0.2 0.5 179, Sunny, High Clouds 10 December 27th 2011 16:06 60 60 760 67 0.1 0.4 167, Sunny, High Clouds INFILTROMETER TEST P -10 504- A05.10 HILLTOP GEOTECHNICAL, INC. PALIZADA V PLATE NO. 11 1800 1600 1400 1200 L x E U c 1000 d �v 0 800 Y �Q L c 600 400 200 0 0 • Infiltration Graph: Infiltration Rate vs. Time P -1 15 30 45 60 90 120 180 240 300 360 Elapsed Time in Minutes --*—Infiltration Rate: Inner Infiltration Rate: Annular 504- A05.10 Hilltop Geotechnical, Inc. Infiltrometer Graph P -1 Plate No. 12 4500 4000 3500 3000 X E U c 2500 'm m 0 2000 �o c 1500 1000 500 0 Infiltration Graph: Infiltration Rate vs. Time P -2 15 30 45 60 90 120 180 240 300 3ti0 Elapsed Time in Minutes --�— Infiltration Rate: Inner M Infiltration Rate: Annular 504- A05.10 Hilltop Geotechnical, Inc. Infiltrometer Graph P -2 Plate No.13 0000000000000000000000000000000000000000000 160 140 120 _ 100 E U c 80 c 0 60 r= c Z Q11 Infiltration Graph: Infiltration Rate vs. Time P -3 we 15 Hilltop Geotechnical, Inc. 30 45 60, 90 120 180 Elapsed Time in Minutes —�-- Infiltration Rate: Inner Infiltration Rate: Annular Infiltrometer Graph P -3 240 300 360 504- A05.10 Plate No.14 25000 KIIIIIl7 E 15000 U C m c 0 R 10000 c 5000 I Infiltration Graph: Infiltration Rate vs. Time P -4 15 30 45 60 90 120 180 240 300 360 Elapsed Time in Minutes - 0 Infiltration Rate: Inner •• i'v - Infiltration RA: 504- A05.10 Hilltop Geotechnical, Inc. Infiltrometer Graph P -4 Plate No.15 m no 0 -^^ UJ CD 0 CD 0 C7 n 0 CD CD UI CD 'D .D CJl � CJ1 O .. 4h. CD Z o 0 CA Cn o V1 W O 7 4' 0) O 7 � O � O m y fD (D Q O 2 ? ?.. 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Infiltrometer Graph P -9 240 300 '360 504- A05.10 Plate No.20 . Infiltration Graph: Infiltration Rate vs. Time P-10 1600 400 1200 1000 800 C 0 600 M11 ✓M 0-1 0 15 30 45 60 90 120 180 240 300 Elapsed Time in Minutes ---*--Infiltration Rate: Inner Infiltration Rate: Annular P 360 504- A05.10 Hilltop Geotechnical, Inc. Infiltrometer Graph P -10 Plate No.21 ?�Fgl�j Vju "i, mm,.1111 u a I mll M., �� � ;u`� P ,tli i ON NMI' 0-11 � 1 *1 �'•.ir4� {� .v INS O n h �1 G't't : .' r'-.�• ". "' . ,: 1 ��� J :-�u.� _ it , �`§2.`a.. ..�tl�' IN <u � ' 'T g SO wlwl IA 1, M TOM � :w� 1� 3Xbit ��F�� INS g INNS 0-1 0 15 30 45 60 90 120 180 240 300 Elapsed Time in Minutes ---*--Infiltration Rate: Inner Infiltration Rate: Annular P 360 504- A05.10 Hilltop Geotechnical, Inc. Infiltrometer Graph P -10 Plate No.21 A; A& HILLTOP GEOTECHNICAL INCORPORATED January 16, 2012 recd v d JAI 2 5 2012 City of La Q eta Funning Department 786 S. GIFFORD AVENUE • SAN BERNARDINO • CALIFORNIA 92408 hilltopg@ligeotech.com • FAX 909 - 890.9055 • 909 -890 -9079 KB Home Southern California Coastal Division 36310 Inland Valley Drive Wildomar, CA 92595 Attention: Mr. Chris Mounts Project No.: 504 -A05 Report No.: 11 Subject: Supplemental Response to City of La Quinta Review Comments, Proposed Renditions at Palizada, Tentative Tract Map No. 36305, Southeast Quadrant of the Intersection of Avenue 60 and Monroe Street, City of La Quinta, Riverside County, California. References: 1. Hilltop Geotechnical, Inc., December 30, 2011, Report of Infiltrometer Testing, Proposed Renditions at Palizada, Tentative Tract Map No. 36305, Southeast Quadrant of the Intersection of Avenue 60 and Monroe Street, in the City of La Quinta, Riverside County, California, Project No.: 504 -A05, Report No.: 10. 2. Hilltop Geotechnical, Inc., December 23, 2011, Report of Geotechnical / Geologic Study Update, Proposed Renditions at Palizada, Tentative Tract Map No. 36305, Southeast Quadrant of the Intersection of Avenue 60 and Monroe Street, City of La Quinta, Riverside County, California, Project No.: 504 -A05, Report No.: 9. 3.- Hilltop Geotechnical, Inc., April 26, 2006, Updated Geotechnical Report, Proposed Residential Subdivisions, Prado Del Sol, Tract Nos. 31732.and 31733, Southeast Corner of Monroe Street and Avenue 60, City of La Quinta, Riverside County, California, Project No.: 504 -A05, Report No.: 8. 504- A05.11 January 16, 2012 Page 2 4. Hilltop Geotechnical, Inc., December 7, 2005, Street Grading Recommendations, Tentative Tract Nos, 31732 & 31733, Southeast Corner of Monroe Street and Avenue 60, La Quinta Area of Riverside County, California, Project No.: 504 - A05, Report No.: 7. 5. Hilltop Geotechnical, Inc., November 28, 2005, Supplemental Geotechnical Recommendations for Foundations on Expansive Soils, Proposed Residential Subdivisions, Tentative Tract Nos, 31732 & 31733, Southeast Corner of Monroe Street and Avenue 60,. La Quinta Area of Riverside County, California, Project No.: 504 -A05, Report No.: 6. 6. Hilltop Geotechnical, Inc., July 18, 2005, Observation of Environmental Cleanup, Contaminated Soil and One 55- Gallon Oil Drum, Proposed Tract Nos. 31732 and 31733, Southeast Corner of Avenue 60 and Monroe Street, La Quinta Area, Riverside County, California, Project No.: 504 -A05, Report No.. 5. 7. Hilltop Geotechnical, Inc., June 2, 2005, Report of Percolation Testing, Proposed Residential Subdivisions, Tentative Tract Nos, 31732 & 31733, Southeast Corner of Monroe Street and Avenue 60, La Quinta Area of Riverside County, California, Project No.: 504 -A05, Report No.: 4. 8. Hilltop Geotechnical, Inc., May 6, 2005, Phase II Environmental Sampling and Analysis, Proposed Tract Nos. 31732 and 31733, Southeast Corner of Avenue 60 and Monroe Street, La Quinta Area, Riverside County, California, Project No.: 504 -A05, Report No.: 3. 9. Hilltop Geotechnical, Inc., April 22, 2005, Report of Geotechnical Study, Proposed Residential Subdivisions, Tentative Tract Nos, 31732 & 31733, Southeast Corner of Monroe Street and Avenue 60, La Quinta Area of Riverside County; California, Project No.: 504 -A05, Report No.: 2. 10. Hilltop Geotechnical, Inc., April 21, 2005, Environmental Assessment, Proposed Tract Nos. 31732 and 31733, Southeast Corner of Avenue 60 and Monroe Street, La Quinta Area, HILLTOP GEOTECHNICAL, INC. 504- A05.11 January 16, 2012 Page 3 Riverside County, California; Project No.: 504 -A05, Report No.. 1. Gentlemen: According to your request, we are responding to a comment from the City of La Quinta as part of the review of the various documents which have been submitted to the City for the subject project as part of the approval and permitting process. The City comments are as follows: Sheet 2 through 4: Please verify all basins HWL have a separation distance of 30 ft from any proposed building foundation. Per additional clarification from the City Public Works Dept., the City has concern regarding possible undermining of building foundations if and when the basins are filled to the high water level during a major storm event. We are presenting, herein, our response to the comments. It is our understanding that the proposed finish elevations for the building pads will be a minimum of 2.0 feet above the design high water elevations and that the retention basins would have all necessary freeboard clearances and outlets for normal storm and emergency events. These are design issues that are addressed by the Civil Engineer for the project as part of the rough and/or precise grading plans for the project. During design high water events, any excess water in the basins should be handled by the design overflow outlets, drains, etc. Percolation of water from the bottom and sides of the retention basins, typically, does not extend laterally outward from the sides of the basins very far. The majority of the percolation is downward and not laterally. With the location of the building pads a minimum of 30 feet from the edges of the basins, saturation of the soils under the pads would not typically occur. Even if saturation were to occur, the compacted soils would not collapse and/or experience any unexpected settlement. In addition, erosion of soils from under the foundations would not occur due to any saturation of soils due to the percolation of the water from within the retention basins. Copies of this response should be forwarded to the City as needed for the approval and permitting purposes. HILLTOP GEOTECHNICAL, INC. 504- A05.11 January 16, 2012 Page 4 This report has been prepared for use by the parties or project named or described above. It may or may not contain sufficient information for other parties or purposes. The findings expressed in this report are based on generally accepted engineering practices and principles. No further warranties are implied or expressed beyond the direct representations of this report. If you have any questions after reviewing the findings and recommendations contained in the attached report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, HILLTOP GEOTECHNICAL, INC. onald . Curran, GE No. 254 Senior Engineer Date Signed: / /X- /� DLC /ah Distribution: (4) Addressee Via U.S. Postal Service (1) Addressee pdf copy Via E -Mail (emounts- x @lcbhome.com) HILLTOP GEOTECHNICAL, INC.