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10-0241 (CSCS) Geotechnical Report- c c 0 e' GEOTECHNICAL REPORT Retail Center -. Washington Street & Calle Tampico La Quinta, California 'Heider Engineering Services Inc. Project Number:060191 Prepared For: . Mr. Dan Almquist The Foundation Group 3857 Birch Street, Ste, 496 Newport Beach, CA 92660 Prepared By: Heider Engineering Services, Inc. 800-A South Rochester Avenue Ontario, CA 91761 April 23, 2007 Ph: (909) 673-0292 FAX: (909) 673-0272 .800-A South Rochester Ave., Ontario CA 91 761-81 71 tt Mr. Dan Almquist* The Foundation Group 3857 Birch'Street, Ste. 496 Newport Beach, CA 92660 Subject: GEOTECHNICAL REPORT Retail Center - Washington Street & Calle Tampico La Quinta, California Heider Engineering Services, Inc. Project No.: 060191 References: 1. Preliminary Site Plan, prepared by Grist Associates., revised date March 12, 2007. Dear Mr. Almquist, According to your request, Heider Engineering Services, Inc. has conducted a Geotechnical Study at the above referenced site for the proposed project. The purpose of this study was to evaluate the existing subsurface conditions within the subject property with. respect to recommendations for grading of the site and geotechnical design recommendations for foundations, concrete slabs on -grade, pavements, etc., for the proposed development. The. conclusions and recommendations presented in this report are preliminary in nature due to the absence of specific grading and/or foundation plans, the formulation of which are subject to the recommendations presented in this report.. Submitted, herewith, are the conclusions and recommendations pertaining to the proposed project as well as the results of our field exploration and laboratory testing, along with the supporting data. Thank you for the opportunity to provide our services. Often, because of design and construction details which occur on a project, questions arise concerning the geotechnical conditions on the site. If we can be of further service or you should have questions regarding this report, please do not hesitate to contact us at your convenience. Because of our involvement in the project to date, we would be pleased to discuss the engineering testing and observation services which may be applicable during grading of the project site and construction of the proposed development. If you would advise us of the appropriate time to discuss these engineering services, we will be pleased to meet with you at your convenience. Respectfully submitted, HEIDER ENGINEERING SERVICES, INC. �fk Exp. 12/31/2007 Dennis W. Heider, RCE 47379 Principal Engineer CML �Q• 9TF0F CAL1F�% TABLE OF CONTENTS EXECUTIVE SUMMARY TATTP OTITTCTrON•..................................................2 AUTHORIZATION.........................................................2 PURPOSE AND SCOPE OF STUDY .......................................... 2 PREVIOUS SITE STUDIES .................................................... 4 PROJECT DESCRIPTION / PROPOSED DEVELOPMENT ........................ 4 DESCRIPTION OF SITE.....................................................5 LOCATION........................................................5 TOPOGRAPHY.....................................................5 SITE ACCESSIBILITY...............................................'5 VEGETATION............................................' ............ 6 STRUCTURES......................................................6 FIELDSTUDY............................................................6 8 LABORATORY TESTING .... ....... .................... .......:...... CLASSIFICATION.................. ................................. 8 IN-SITU MOISTURE'CONTENT AND DRY DENSITY TEST ................. 8 9 CONSOLIDATION TEST ........................................ MAXIMUM DRY DENSITY / OPTIMUM MOISTURE CONTENT RELATIONSHIP TEST .................... 9 DIRECT SHEAR TEST .............................................. 10 TEST 10 PARTICLE SIZE ANALYSIS .................................... SITECONDITIONS .......................................................10 10 EARTH MATERIALS DESCRIPTION .................................. Topsoil.. .......... .....................................11 Alluvium ..................... .............................11 '...................... 11 HYDROLOGY............................... Surface Water ................................................I1 Groundwater........................ ....................11 ...................... 12 SUBSURFACE VARIATIONS ........... ....... 12 CONCLUSIONS AND RECOMMENDATIONS ............................. • .. SITE PREPARATION RECOMMENDATIONS ....................:....: 13 14 Final Grading Plan Review ...................................... Clearingand'Grubbing.........................................14 Excavation Characteristics ...................................... 15 Suitability of On -Site Materials as Fill ............................. 15 Removal and Recompaction....................................... 15 Import Material ...................................... . ....... 17 Fill Placement Requirements ............. ..................... 17 Compaction Equipment ....... 17 Shrinkage; Bulking, and Subsidence : 18. Abandonment of Existing Underground Lines ....................... 18 Protection of Work ............................................. 19 Observation and Testing ........................................ 19 Soil Expansion Potential ........................................ 20 Soil Corrosion Potential ....... I ........................... I ..... 20 Liquefaction Potential ........................................... 21 CBC SEISMIC DESIGN CRITERIA ............... ..... 21 FOUNDATION DESIGN RECOMMENDATIONS ........................ 22 Foundation Size......... ....................................... 23 Depth of Embedment ........................................... 23 Footing Setback..............................................23 Bearing Capacity..........................................:...24 Settlement ........................................... .....24 Lateral Capacity ........................ ....................24 Interim Foundation Plan Review ......... 25 Final Foundation Design Recommendations' .............:.......... 26 Foundation Excavations ........ ......................... ......26 SLAB -ON -GRADE. RECOMMENDATIONS ............................. 26 Exterior Slabs .................................................. 28 Concrete Corrosion .......... ......... ......... .............. 28 PRELIMINARY PAVEMENT RECOMMENDATIONS .......................... 29 POST -GRADING CRITERIA ................................................ 31 UTILITY TRENCH RECOMMENDATIONS .......... .... • . • . . • • • • . • • • • • • • • • 32 FINISH SITE DRAINAGE RECOMMENDATIONS .............................. 34 PLANTER RECOMMENDATIONS....... ........... ........................ 35 PLAN AND SPECIFICATION REVIEW ....................................... 35 PRE-BID CONFERENCE ........................... 36 PRE -GRADING CONFERENCE ............................................. 36 CONSTRUCTION OBSERVATIONS AND TESTING ........................... 36 CLOSURE......................I...........................; I ...........37 APPENDIXI.............................................................:. .DRAWINGS ............ ............................................... APPENDIXII............................................................ SOILBORING LOGS ................................................. APPENDIXHI*... I ......................................... LABORATORTEST RESULTS ....................................... ' Retail Center - La Quinta, California' Washington Street& Calle Tampico Project No.: 060191 April 23, 2007 Page 1 EXECUTIVE SUMMARY. A geotechnical study of the subsurface conditions of the subject site has been performed for the proposed Retail Center located at the NW Corner of Washington Street & Calle Tampico in La Quinta, CA. Exploratory excavations have been performed and earthmaterial samples subjected to laboratory testing. The data has been analyzed with respect to the project information furnished for the proposed project. It is the opinion of this firm that the proposed project is '. feasible from a geotechnical standpoint, provided that the recommendations presented in this report are followed in the design and construction of the project. It is deemed that the near -surface soils on the site are satisfactory for support of structural fills, shallow foundations, floor slabs, exterior hardscape, and pavement, with some recompaction of the near -surface soils. The near -surface soils on the site have a `Very Low' expansion potential as determined by Table 18A -1-B, `Classification of Expansive Soil,' in the 2001 California Building Code (CBC). Therefore, a conventional shallow foundation system utilizing spread footings and continuous wall footings appears to be the most appropriate type of support for the proposed structure.. Analysis of the subsurface conditions and recommendations for grading, foundations, floor slabs, exterior hardscape, pavements, etc., are presented in the following sections. AUTHORIZATION INTRODUCTION Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 2 This report presents the results of the geotechnical study conducted on the subject site for the proposed Retail Center. Authorization to perform this study was in the form of a signed copy 'J of Heider Engineering Services, Inc.'s proposal number: HE06120, dated August 11, 2006. PURPOSE AND SCOPE OF STUDY The scope of work performed for this study was designed to determine and evaluate the surface and subsurface conditions on the subject site with respect to geotechnical characteristics, 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: . • Telephone conversations with the client. e Site reconnaissance. ® Subsurface exploration by means of borings to characterize soil, geologic, and groundwater conditions that could influence the proposed development. ® Sampling of on-site earth materials fiom the exploratory excavations. s Laboratory testing of selected earth material samples considered to be representative of the subsurface conditions to determine the engineering properties and characteristics. ® Engineering analysis of field and laboratory data to provide a basis for our conclusions and recommendations regarding site grading and foundation, floor slab and pavement design parameters. ® Preparation of this report to present the geotechnical conclusions and recommendations for site development. Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007, Page 3 This report presents our conclusions and/or recommendations regarding: • General subsurface earth conditions. • Presence and effect of expansive, collapsible, and compressible soils. • 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. • Types and depths of foundations. • Allowable bearing pressures and lateral resistence. for compacted fill materials. • Estimated total and differential settlements of foundations. • Utility trench excavation and backfill recommendations. The scope of work performed for this report did not include any testing of soil or groundwater for environmental purposes, an environmental assessment of the property, or opinions relating . to the possibility of surface or subsurface contamination by hazardous or toxic substances. In addition, evaluation of on-site private sewage disposal systems for the proposed development was not part of this study. This study was prepared for the exclusive use of The Foundation Gi-oup. and their consultants for specific application to the Retail Center Project located in La Quinta, CA in accordance with generally accepted standards of the geotechnical profession and generally accepted geotechnical engineering principles and practices at the time this report was prepared. No other warranty, implied or expressed, is made. Although every reasonable effort has been made to obtain information regarding the geotechnical and subsurface conditions of the site, limitations exist with respect to the knowledge of unknown regional or localized off-site conditions which may Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 4 have an impact at the site. The conclusions and recommendations presented in this report are valid as of the date of the report. However, changes in the conditions of a property can occur with the passage of time, whether they are due to natural processes or to the works of man on this and/or adjacent properties. If conditions are observed or information becomes available during the design and construction process which are not reflected in this report, Heider Engineering Services, Inc. should be notified so that supplemental evaluations can be performed and the conclusions and recommendations presented in this report can be modified or verified in writing as necessary. Changes in applicable or appropriate standards of care in the geotechnical profession 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 control of the geotechnical consultant which occur in the future. PREVIOUS SITE STUDIES No previous geotechnical or grading studies for the subject property were available for review at the time of this study. PROJECT DESCRIPTION / PROPOSED DEVELOPMENT As part of our study, we have discussed the project with Mr. Dan Almquist. We have also been provided with a 'Preliminaiy Site Plan from Grist Associates. Based on information presented to this firm, it is our understanding that the proposed proj ect will consist of a single story building with moderate foundation loads with column loads'less than 20 kips and wall loads less than 5 kips per linear foot. It is anticipated that the building will be constructed utilizing conventional'slab-on-grade construction with the building pad elevation Retail Center - La Quinta, California Washington Street & Calle Tampico _ Project No.: 060191 April 23, 2007 Page 5 within a few feet of the current elevation on-site. We anticipate that wood framing and/or light gauge metal stud construction will be utilized. Associated parking and driveway areas are also planned. Utility line installation for the project will likely be through cut -and -cover techniques. Soils from the excavation will be placed in the trench zone as compacted fill. The above project description and assumptions were used as the basis for the field exploration, laboratory testing program, the engineering analysis, and the conclusions and recommendations i.. presented in this report. Heider Engineering Services, Inc. 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. DESCRIPTION OF SITE LOCATION The subject property for which this preliminary geotechnical study has been performed comprises approximately 0.50 acres as plotted. on the building plan prepared by Grist Associates. The subject properly is located on the North side of Calle Tampico, approximately 150 feet West of Washington Street in La Quinta, CA. TOPOGRAPHY The topography of the site at the time of this study was fairly flat with an estimated difference in. elevation "across the site of less than 2 feet: Along the South portion of the site is a drainage swale which is estimated to be approximately 4 feet lower in elevation that the existing grade of ` the building pad.. SITE ACCESSIBILITY At the time the field exploration was made, the surface of the site was firm and the drilling equipment did not experience any difficulty in moving around on the site. Retail Center - La Quinta, California Washington Street & Calle Tampico _ Project No.: 060191 April 23, 2007 Page. 6 VEGETATION At the time of the field study the site was covered with grass and is part of an undeveloped - portion of a larger retail center. STRUCTURES There were no structures present on the immediate site at the time of our field study. This property is part of a developed retail center with much of the site developed with retail buildings. FIELD STUDY The field study performed for this report included a visual reconnaissance of the existing surface conditions of the subject site. Site observations were conducted on August 28, 2006 and April 8, 2007 by representatives of Heider Engineering Services, Inc. A study of the property's subsurface condition was performed to evaluate underlying earth strata and the presence of groundwater. Three (3) exploratory borings were performed on the study'site . in the area of the proposed structures and pavement areas on April 8, 2007. The locations of the exploratory excavations were determined inthe field by pacing, measuring and sighting fiomthe adjacent existing streets as shown on the Reference No. 1 `Preliminary Building Plan.' The approximate locations of the exploratory excavations are denoted- on this plan, presented in the ' Appendix. The locations of the exploratory excavations should be considered accurate only to the degree implied by the method used in determining them. The exploratory borings were performed using a track -mounted CME 75 drill rig equipped with 8 -inch outside diameter, hollow stem augers. The exploratory excavations were explored to depths ranging from approximately 21.5 feet to 41.5 feet below the existing ground surface at the excavation locations. Bulk and relatively undisturbed samples of the earth materials encountered were obtained at various depths in the exploratory excavations and returned to our Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 7 laboratory for verification of field classifications and testing. Bulk samples were obtained from cuttings developed during the excavation process and represent a mixture of the soils within the depth indicated on the logs. Relatively undisturbed samples of the earth materials encountered were obtained by driving a thin-walled steel sampler lined with 1 -inch high, 2:40 -inch inside diameter brass rings (California Sampler). The sampler was driven with successive drops of a 140 -pound weight having a free fall of approximately 30 inches. The blow counts for the last 12 inches of penetration, or fiaction thereof, are shown on the Boring Logs, presented in the Appendix. The ring samples were retained in close -fitting moisture -retaining containers and returned to our laboratory for testing. Standard Penetration Tests were also performed at various depths in one of the borings.. The test was performed in general accordance with American Society of Testing Materials (ASTM) D1586 procedures using a standard penetration sampler (2.0 -inch outside diameter, 1.375 -inch inside diameter) driven with a 140 weight dropping 30 inches. The standard penetration resistance ('N' value) is the sum of the blow counts for the last two (2), 6.0 inch intervals. The exploratory excavations were logged by our representative for earth materials and subsurface conditions encountered. Water level observations were made during, and at the completion of, the excavation process and are noted on the boring logs, when encountered. The soil materials encountered in the exploratory excavations were visually described in the field. The visual textural description, the color ofthe soil at natural moisture content, the apparent moisture condition ofthe soil materials, and the apparent density or consistency of the soils, etc, were recorded on the field logs. The density of granular soils is given as loose to dense and is based on the number of blows required to drive the sampler. The field log for each excavation contains factual information and interpretation of soil conditions between the samples. The Boring Logs presented in the Appendix represent our interpretation of the contents of the field logs and the results of the laboratory observations and tests performed on the samples obtained in the field from the exploratory excavations. The exploratory boring excavations were backfilled with excavated soil with reasonable effort to restore the areas to their initial condition before leaving the site. In an Retail Center - La Quinta, California Washington Street & Calle Tampico, Project No.: 060191 April 23, 2007 s Page 8 area as small and deep as a boring excavation, consolidation and subsidence of the backfill soil may result in time, causing a depression of the excavation areas. The client is advised to observe the exploratory excavation areas periodically and, when needed, backfill noted depressions. Heider Engineering Services, Inc. shall not be liable for any injury or damage resulting from subsidence of the backfill. LABORATORY TESTING Relatively undisturbed ring samples and representative bulk samples of on-site fill and natural earth materials were collected during'the field exploration and returned to the laboratory for i testing. Laboratory tests were conducted to evaluate the index and engineering properties of on- site materials. The results of the laboratory tests performed are presented in the Appendix. Following is a listing and brief explanation of the•laboratoly tests which were performed. The remaining samples obtained during the field study will be discarded 30 days after the date of this report. This office should be notified immediately if retention of samples will be needed beyond 30 days. . CLASSIFICATION The field classification of soil materials encountered in the exploratory excavations was verified , in the laboratory in general accordance with the Unified Soils Classification System, ASTM D2488, Standard Practice for Determination and Identification of Soils (Visual -Manual Procedures). The soil classification is shown on the `Boring Logs presented in the Appendix. IN-SITU MOISTURE CONTENT AND DRY DENSITY TEST _ The in-situ moisture content and dry density were determined in general accordance with ASTM D2216 and D2937 procedures, respectively, for selected soil samples. The dry density is determined in pounds per cubic foot and the moisture content is determined as a percentage of the oven dry weight of the soil. This information was used as an aid to classification and Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 9 permitted recognition of variations in material consistency with depth. Test results are shown on the boring logs presented in the Appendix. CONSOLIDATION TEST Settlement predictions of the compacted fill behavior under load were made based on consolidation tests that were performed in general accordance.with current ASTM D2435 procedures. The consolidation apparatus is designed to receive a 1 -inch high, 2.40 -inch diameter ring sample. Porous stones are placed in contact with the top and bottom of each specimen to permit addition and release of pore water and pore pressure. Loads normal to the face of the . specimen are applied in several increments in a geometric progression under both in-situ moisture and submerged conditions. The resulting changes in sample thickness are recorded at selected time intervals. Water was added to the test apparatus at a load of 1,100 psf to create a submerged condition and to measure the collapse potential (hydroconsolidation) of the sample. i The test results are summarized on the Consolidation Graphs presented in the Appendix. MAXIMUM DRY DENSITY / OPTIMUM MOISTURE CONTENT RELATIONSHIP TEST A Maximum dry density / optimum moisture content relationship determinations was performed on a sample of near -surface earth material in general accordance with ASTM D 1557, Procedure. A, using a 4 -inch diameter mold. Samples were prepared at various moisture contents and compacted in five (5) layers using a 10 -pound weight dropping 18 inches and with 25 blows per layer. A plot of the compacted dry density versus the moisture content of the specimens is . constructed. and the maximum dry density and optimum moisture content determined fiom the plot. The test results are presented in the Appendix. • DIRECT SHEAR TEST Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 10 Direct shear tests were performed on selected samples of near -surface earth material in general accordance with ASTM D3080 procedures. One sample was tested on a remolded sample, which was remolded to 90% of the maximum dry density as determined by ASTM D 1557. Two samples were tested on undisturbed samples obtained fiom the field sampling. The shear machine is of the constant strain type. The shear machine is designed to receive a 1 -inch high, 2.40 -inch diameter ring sample. Tlu-ee (3) specimens from the `samples were sheared at various pressures normal to the face of the specimens. The specimens were tested in a submerged condition. The ultimate shear stresses were plotted verses the normal confining stresses to deteimine the shear strength (cohesion and angle of internal friction). The test results are presented in the Appendix. PARTICLE SIZE ANALYSIS TEST Particle size analyses were performed on selected samples of earth material in general accordance .with ASTM D422 procedures. The test is performed by taking an oven dry sample of soil material, washing it over a No. 200 sieve, drying the soil retained on the No. 200 sieve, and then shaking it over the #4 sieve and the 4200 sieve. The weight of soil material retained on each sieve size is measured and the resulting'percentage retained on each sieve is calculated based on the original total dry sample weight. The percentage passing each sieve is calculated and presented on the boring log for Boring B-1 and is presented in the Appendix. SITE CONDITIONS EARTH MATERIALS DESCRIPTION Presented below are brief descriptions of the earth materials 'encountered in the exploratory excavations. More detailed descriptions of the earth materials encountered are presented on the -. Boring Logs are presented in the Appendix. The earthmaterial stratum as shown on the logs represent the. conditions in the actual exploratory excavation locations. Other variations may occur between and/or beyond the excavation locations. Lines of demarcation between the earth I Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page I 1 materials on the logs represented the approximate boundary betweenthe material types; however, the transition may be gradual. Topsoil Approximately four (4) inches of topsoil was encountered on the site with a manicured grass lawn covering the site.. Alluvium Deposits of alluvial materials were encountered across the site. These materials were encountered from near surface and extending to the maximum boring depth of 41.5 feet below the existing ground surface. Alluvial materials encountered generally consisted of brown fine to medium silty SANDS and sandy SILTS.. The encountered soils were found to be slightly moist to moist and loose in density, as observed by drilling resistance and standard penetration tests. HYDROLOGY Surface Water At the time of the site exploration, surface drainage appeared to be fair with the site topography being fairly flat. Groundwater Groundwater was not encountered in the exploratory excavations, either during the drilling operations or after removal of the drill augers. The borings were performed to a maximum depth of 41.5 feet below the existing ground surface. Indications of historical high groundwater conditions were not observed within the exploratory excavations. SUBSURFACE VARIATIONS Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 12 Based on the results of our subsurface exploration and. experience; some variations in the continuity and nature of subsurface conditions should be anticipated. Due to the uncertainty involved in the nature and depositional characteristics of the earth materials at the site, care should be exercised in extrapolating or interpolating subsurface conditions between and beyond the exploratory boring locations. Water level readings were made in the exploratory excavations at times and under conditions stated on the boring logs. These data have been reviewed and interpretations made in the text in other sections of this report. However, it should be noted that fluctuations in the level of the groundwater may occur due to variations in precipitation, temperature, and other factors which were present at the time measurements were made. CONCLUSIONS AND RECOMMENDATIONS The conclusions and recommendations presented in this report are, in pail, based on information provided to us, the results of our field and laboratory data obtained from 3 exploratory excavations located across the subject property, 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 standpoint providing the recommendations contained within this report are adhered to during project design and construction. 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 between the exploratory excavations may not become evident until construction. If variations of the material become ,evident during construction of the proposed development, Heider Engineering Ser 0ces, Inc. Retail Center,;r La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 13 should be notified so that the geotechnical 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 and pavement design are presented iii the subsequent paragraphs. SITE PREPARATION RECOMMENDATIONS The grading recommendations presented in this report are intended for: 1) the rework of unsuitable, near -surface, earth materials to create engineered building pads and 'satisfactoiy support for exterior hardscape (i.e., sidewalks, etc.) and pavement; and 2) the use of a conventional, shallow foundation system and concrete slabs cast on -grade. If hardscape and pavement subgrade soils are prepared at the time of rough grading of the building site and the improvements are not constructed immediately, additional observations and testing of the subgrade soil will have to be performed before placing aggregate base material or asphaltic concrete, or Portland Cement Concrete to locate areas which may have.been damaged by construction traffic, construction activities, and/or seasonal wetting and drying. The following recommendations may y need to be modified and/or supplemented during rough grading as field conditions dictate. The grading should. be performed in accordance with the recommendations presented in this report. It is recommend that Heider Engineering Services, Inc. be retained by the owner of the proposed project to observe the excavation and grading operations and test the compacted fill and backfill. A pregrading conference should be held at the site with the Owner's Representative, the project Arc ' ect, the project Cn•ading Contractor, the proj ect Civil Engineer, and the project Geotechnical Consultant in attendance and special grading procedures can be addressed at that time. Earthwork observation services allow the testing of only a small percentage of the fill placed'at ontractor should contain the provision that the site. Contractual arrangements with the grading?, Retail Center - La Quinta, California . Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 14 lie is responsible for excavating, placing, and compacting fill in accordance with project specifications. Observation by the project Geotechnical Consultant during grading should not relieve the grading contractor of his responsibility to perform all work in accordance with the project specifications. The following recommendations may need to be modified and/or supplemented during grading as field conditions require. Final Grading Plan Review Final grading plans should be reviewed by Heider Engineering Services, Inc. when -they become available to address the suitability of the grading recommendations presented in this report with respect to the proposed improvements. Clearing and Grubbing Any encountered deleterious materials should be removed from the proposed building, exterior hardscape and pavement areas and areas before final grading is performed. Any miscellaneous debris should -be legally disposed of off site, including all encountered asphaltic concrete pavement, portland cement concrete pavement, concrete foundations, building debris and other miscellaneous construction debris. Man-made objects encountered (i.e., irrigation systems, underground utilities, old foundations, etc.) should be overexcavated, exported from the site, and legally disposed of off site. If a cesspool is encountered, (none were encountered during this study), it should be pumped free of any liquid and filled with a low strength sand cement slurry to an elevation 5.0 feet below the final site grade in the area. The upper 5.0 feet of the cesspool should be excavated and the area backfilled with a properly compacted fill material. The location of the cesspool should be surveyed and plotted on the final as -graded plan prepared by the project Civil Engineer. Wells, if encountered, should be abandoned and capped according to directions and supervision of Riverside County Department of Health, the State of California, . Retail Center - La Quinta, California Washington Street_& Calle Tampico _ Project No.: 060191 April 23, 2007 Page 15 and/or the appropriate governmental agency procedures which has jurisdiction over the well before fill and/or pavement is placed over the area. Excavation Characteristics Excavation and trenching within the subject property is anticipated to be relatively easily -moving equipment since the drill rig equipped with flight accomplished with conventional earth augers was able to penetrate to the indicated depths. No significant amounts of rock materials are anticipated to be generated fi-om the cuts performed in the local materials. Materials were not encountered or are anticipated that would require blasting to excavate. Suitability of On -Site Materials as Fill In general, the on-site earth materials present below any topsoil are considered satisfactoiy for reuse as fill. Fill materials should be flee of significant amounts of organic materials and/or debris and should not contain rocks or clumps greater than.3.0 inches in greatest dimension. It is noted that the in-situ moisture content of the upper soils is slightly moist to very moist with moisture contents on the order of 4 to 26 %. The optimum moisture content for the upper soils was found to be 13.0%. Therefore moisture conditioning of the soils will be required to achieve a uniform moisture content near the optimum moisture content of 13.0%. Removal and Recompaction Unsuitable, loose, or disturbed near -surface natural soil and incompetent alluvium in proposed areas which will support structural fills, structures, exterior hardscape (i.e., sidewalks, etc.), and pavement should be prepared in accordance with the following recommendations for grading in such areas. It is noted that fill placed to support sidewalks, retaining walls„ driveways, and pavement are considered to be structural fill. ® The near -surface soils . on the Bite are recommended to be overexcavated and recompacted: Based upon our borings and laboratory test results, we recommend that the overexcavation extend to a depth of 2.0 feet below the foundations. areas for building I Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 16 structures, retaining walls, and site walls. In addition the upper 2.0 feet of the existing grade, in building areas, should be moisture conditioned and recompacted before any fill is placed. Moreover, the depth of the overexcavation within the perimeter of a proposed. building structure should be to a uniform elevation throughout the limits of the structure. The limits of overexcavation for building pads should extend to a distance of 5.0 feet beyond the structure perimeter or footing edges. The limits of overexcavation for perimeter wall footings and/or retaining wall footings should extend to a distance of 2.0 feet beyond the footing edges. The limits of processing or overexcavation for exterior hardscape and pavement areas should extend to a distance of 2.0 feet beyond the edge of the exterior hardscape or pavement. The exposed overexcavation bottom surfaces for the foundation and buildings should be scarified to a depth of 8 inches, brought to a moisture content of 12% to 16% 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.. ® In the proposed exterior hardscape (i.e., sidewalks, etc.), and pavement areas where structural fill is not to be placed or cuts are proposed, the existing near -surface soils need only be moisture conditioned and recompacted to a depth of 12 inches below proposed subgrade elevation. The limits of recompaction for exterior hardscape and pavement areas should extend to a distance of 2.0 feet beyond the edge of the exterior hardscape or pavement. The scarified soils should be brought to a moisture content of 6 % to 9% and compacted to 90 percent or greater relative compaction. Maximum dry density and optimum moisture content for compacted materials should be determined according to current ASTM D 1557 procedures. 0 In .landscape or non-structural areas where non-structural fill will be placed, no overexcavation or reworking of the exposed soils is required. ® Itis noted that localized areas, once exposed, may warrant additional overexcavation for the removal of any existing soft or loose soils, and subsurface obstructions and/or debris which may be associated with the past usage of the site. Actual depths of removals and the competency of the exposed overexcavation bottoms should be determined by the project Geotechnical Consultant and/or his representative during grading operations at the time they are exposed and before scarification and recompaction or the placement of fill. Import Material n Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.:' 060191 April 23, 2007 Page 17 Import fill should not'be more expansive in nature. than the existing on-site material as determined by 1997 UBC Standard 18-2 procedures and have strength parameters equivalent to or greater than the on-site soils. Import fill material should be approved by the Geotechnical Consultant prior to it being brought on-site. Fill Placement Requirements Fill material, whether on-site material or import, should be approved by the project Geotechnical Consultant and/or his representative before placement. Fill material should be free from vegetation, organic material, debris, and oversize material. Approved fill material should be ; placed in horizontal lifts not exceeding 8.0 inches in compacted thickness and watered or aerated to moisture content with -1.0% to plus 3.0% of the optimum moisture content, as determined by ASTM D 1557. Each lift should be spread evenly and should be thoroughly mixed to ensure uniformity of soil moisture. Structural fill should be compacted to 90 percent or greater relative compaction. Landscape fill and/or non-structural fill need only be compacted to 85 percent or greater relative compaction. Maximum dry density and optimum moisture content for compacted materials should be determined in accordance with current ASTM D 1557 procedures. Compaction Equipment It is anticipated that the compaction equipment to be used for the project will include a combination of rubber -tired and smooth drum 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 is the responsibility of the contractor performing the work and should. be such that uniform compaction of the fill is achieved: Shrinkage, Bulking, and Subsidence I#— �" J S �s �c- 1�. 5� L. Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 18 There will be a material loss due to the clearing and grubbing operations. The following values are exclusive of losses due to clearing, grubbing, tree root removal, or the removal of other subsurface features and may very due to differing conditions within the project boundaries and the limitations of this study. Volumetric shrinkage of near surface soils that is excavated and replaced as controlled, compacted fill should be anticipated. It is estimated that the average shrinkage of the near -surface soils will be approximately 5.0 to 10 percent, based on fill volumes when compacted to 90 to 95 percent relative compaction. For example, a 5.O percent and 10 percent shrinkage factors would mean that it would take 1.05 and 1.10 cubic yards of excavated material to make 1.0 cubic yard of compacted fill at 90 percent and 95 percent relative compaction, respectively. A higher relative compaction would mean a larger shrinkage value. 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 in 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 alternative: 11 Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 20 eq observe 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 Consultant when cleanout and/or overexcavation bottoms are ready for observation and prior to scarification and recompaction. 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 Consultant and/or his representative present may result in exclusions of the affected areas from the rough or finish grading reports for the project. The presence of the project Geotechnical 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 Consultant and/or his field representative nor the field observations and testing should excuse the contractor for defects discovered in the contractor's work. Soil Expansion Potential Upon completion of grading of the building pad areas, near -surface samples should be obtained for expansion potential testing to verify the preliminary expansion test results and the foundation and slab -on -grade recommendations presented in.this report. Soil Corrosion Potential Upon completion of grading of the building pad areas, near -surface samples should be obtained for corrosion potential testing to verify the preliminary chemical test results and the W recommendations for protection of concrete and bare metal which come in contact with the on- site soils presented in this report. Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 21 Liquefaction Potential 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 excess porewater escapes. 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. It has been shown by laboratory testing and from the analysis of soil conditions at sites where liquefaction has occurred that the soil types most susceptible to liquefaction are saturated, fine sand to sandy silt with a mean grain size ranging from approximately 0.075 mm to 0.5 mm. 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 and silty or clayey sands beyond, the above mentioned grain size range are considerably less vulnerable to liquefaction. To a large extent, the relative density of the soil also controls the susceptibility to liquefaction 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 the 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. Based upon our observations, including the encountered deposits to the explored depth of 41.5 feet and groundwater levels below the explored depth of 41.5 feet, liquefaction is not considered to be a concern for this project. CBC SEISMIC DESIGN CRITERIA Based upon our understanding of local geologic conditions and limited in-situ penetration tests performed concurrent with this study, the "Soil Profile Type" judged applicable to this site is Se, Retail Center - La .Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 22 generically described as a "Soft Soil' profile per Table 16A -J, "Soil Profile Types," in the 2001 CBC with an average Standard Penetration Test value of less than 15 blows per foot of penetration in the upper 100 feet of the site. The property is located within CBC Seismic Zone 4, per Figure 16A-2. The following table presents additional coefficients and factors relevant to seismic mitigation for new construction built according to the 2001 CBC. Seismic Seismic Distance Near Seismic Near Seismic Source* Source From Site Source Coef:. Source Coef. Type* (km)* Factor (Ca)** Factor (Cv)** (Na)** (Nv)** San Andreas A 12.0 1.00 0.36 1.12 1.08 Fault southern - *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. **Table 16A -Q, `Seismic Coefficient Ca,' Table 16A -R, `Seismic Coefficient Cv,' Table 16A -S, `Near Source Factor Na,' and Table 16A -T, `Near Source. Factor Nv,' in the 1998 CBC. FOUNDATION DESIGN RECOMMENDATIONS - Foundations for the proposed structures may consist of conventional column footings and . continuous wall footings founded upon documented, properly compacted fill. The recommendations presented in the subsequent paragraphs for foundation design and construction are based on geotechnical characteristics and a `Very Low' expansion potential for the Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 23 supporting material as determined by Table 18A -1-B, `Classification of Expansive Soil,' in the 1998 CBC and should not preclude more restrictive structural requirements. The Structural Engineer for the project should determine the actual 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 necessary for the soil conditions present on the site and are not intended to supersede the design of the. project Structural Engineer or the criteria of the governing agencies for the project. Foundation Size Continuous footings should have a width of 24 inches or greater. Column footings should have Com. a width of 36 inches by ,36 inches or greater and be suitably reinforced, based on structural requirements: .............I..... ................................ De th of Embedment Exterior and interior footings should extend to a depth of 18 inches or greater below lowest adjacent finish grade. Footings should be founded in documented, properly compacted fill. Frost is not considered a design factor for foundations in the City of La Quinta, California area since there is no significant frost penetration in the winter months. Where building or retaining wall, footings will be constructed directly on the property line or. where the limits of overexcavation do not extend sufficiently beyond the footing edges per the `Earthwork Recommendations' section of this report, the footings should be deepened to extend to a minimum depth of�24 inc esh below final grade. Footing Setback Embedment of footings on or near planned slopes should be determined by a setback distance measured from the bottom outside edge of the footing to th6 slope face according to Figure 18A - I -1, `Setback Dimensions,' in the 1998 .CBC or to a distance of 5.0 times the footing width, whichever is greater. Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 - April 23, 2007 Page 24 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 1500 psf for footings that are 24 inches in width and a depth of embedment of 18 inches below lowest adjacent finish grade for footings founded in firm, properly compacted fill material. This value may be increased by 20 percen for each additional foot of depth and/or foot of width to a value of up to 3.0 times the designated allowable bearing value. For eccentrically loaded footings and/or overturning moments, the resultant force should be in the middle one-third of the footing I �� 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. 3 2 old Settlement ? Footings designed according to the recommended bearing value for continuous and column ! 20 footings, the assumed maximum wall and column loads, and founded in undisturbed, properly 2 0 1.0 inches or a �0 comp acted fill material are not expected to exceed a total settlement of differential settlement of 0.50 inch between similarly sized and loaded footings. 000 Lateral Capacity .Resistance to lateral loads can be provided by a combination of friction acting at the base of the slab or foundation and passive earth pressure on the sides of the footings and stem walls. The design parameters for lateral resistance to static lateral dead forces, are as follows: � d Retail Center - La Quinta, California Washington Street & CalIe Tampico Project No.: 060191 April 23, 2007 Page 25 Allowable Lateral Bearing Pressure (Equivalent Fluid Pressure), Passive Case: Properly Compacted Fill - 150 lbs/sq. ft./ ft. of depth Allowable Lateral Sliding Coefficient Between Soil and Concrete: Undisturbed, Properly Compacted Fill =_0.25___( 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 soil mass extending to a distance of 10 feet or greater from the face of the footing, 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 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 passive pressure is 15 times the recommended design value. Interim Foundation Plan Review It is recommended that Heider Engineering Services, Inc. review the foundation plans for the structure 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. 0 Final Foundation Design Recommendations Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.; 060191 - April 23, 2007 Page 26 Final foundation recommendations should be made upon completion of grading and be included in the Grading Report prepared by the Geotechnical Consultant for the project. Foundation Excavations Foundation excavations should be observed by the a representative of the project Geotechnical Consultant 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. Foundation excavations should be trimmed neat, level, and square. 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. Soils removed from the foundation excavations should not be placed in slab -on -grade areas unless compacted to 90 percent or greater relative compaction. The maximum dry density and optimum moisture content for the soil should be determined in accordance with current ASTM D1557 procedures. SLAB -ON -GRADE RECOMMENDATIONS. The recommendations for concrete slabs, both interior and exterior, excluding Portland Cement Concrete (PCC) pavement, are based upon a `Very Low" expansion potential for the supporting material as determined by Table 18A -I -B, `Classification of Expansive Soil,' in the 2001 CBC. The expansion potential of the slab subgrade areas should be verified at the completion of grading. Concrete slabs should be designed to minimize cracking as a result of shrinkage. Joints (isolation, contraction, and construction) should be placed in accordance with current American Concrete Institute (ACI) 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 Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 27 with current ACI recommendations and procedures. 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. In areas where moisture sensitive floor coverings are anticipated over the floor slab, we recommend the use of a polyethylene sheet vapor barrier or retarder with a 10 -mil or greater thickness, or an equivalent substitute, be placed beneath the slab. The vapor barrier or retarder material should be in accordance with current ASTM E1745, `Standard Specification for Plastic Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs,' criteria. The installation of the vapor barrier or retarder should be in accordance with current ASTM El 643, `Standard Practice for Installation of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs,' criteria. The vapor barrier or retarder should be covered by a 1.0 inch to 2.0 inch thick layer of moist (not saturated). sand to aid in concrete curing and to minimize potential punctures. Sand as defined by the Unified Soil Classification System, ASTM D2488 includes poorly graded sands (SP), well graded sands (SW), and silty sands (SM). However, clayey sands (SC) are not recommended to be used above the vapor.barrier. The sand should be moistened (not saturated) immediately prior to placing the concrete. If the vapor barrier or retarder 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 or 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 or retarder from punctures. If gravel bedding is used, it should consist of a well Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 — April 23, 2007 Page 28 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. Exterior Slabs Exterior concrete slabs cast on finish subgrade (i.e., 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 soil that has been prepared in accordance with the Earthwork Recommendation section of this report. Subgrade soils should be moisture conditioned to within minus 1% to plus 3% of the optimum moisture content to a depth of 12 inches and proof compacted to 90 percent or greater relative compaction based on cui7ent ASTM D1557 procedures immediately before placing aggregate base material, placing reinforcing steel, or placing the concrete. Concrete Corrosion Soils with a water soluble sulfate (SO4) concentration in the range of 0.0 percent to 0.10 _ percent are considered to have a `Negligible' sulfate exposure to concrete which comes in contact with the on-site soil as defined in Table 19A -A-4, `Requirements for Concrete Exposed to Sulfate -Containing Solutions,' in the 2001 CBC. Therefore, the 2001 CBC should be used to determine the type cement and the maximum water cement ratio to be used in concrete which comes in contact with the on-site soils. A lower water / cement ratio or higher compressive strength may be required for design of concrete for water tightness or for protection against corrosion of embedded metallic items per Table 19A -A-2, `Requirements for Special Exposure Conditions,' in the 2001 CBC. Experience in the southern California area has shown that even though the soils may not contain levels of soluble sulfate which would require the use of sulfate resistant cement and maximum water cement ratios in concrete, concrete corrosion and erosion problems still occur. These problems are the result of concentratioris 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 soil amendments used to promote plant growth (i.e., some domestic water sources contain levels r Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 29 of soluble sulfate which would be a moderate sulfate exposure to concrete which comes in contact with it). Therefore, it may be wise to use a concrete designed for a moderate exposure to sulfate per the criteria presented in Table 19A -A-4, `Requirements for Concrete Exposed to Sulfate -Containing Solutions,' in the 2001 CBC that comes into contact with the on-site soils and/or surface run-off or other sources of water if this is considered to be problematic. Higher strength, lower water / cement ratio, and denser concrete may also be effective in reducing the potential for evapotianspiration to occur and preventing damage due to salt or acid exposure. PRELIMINARY PAVEMENT RECOMMENDATIONS The following are our preliminary recommendations for the structural pavement section for the proposed parking areas and driveway areas for the subj ect development. The pavement sections have been determined in general accordance with CALTRANS design procedures and are based on an assumed Traffic Index (TI) for a 10 year design life and an assumed R -Value of at least. 25 based on past experience in the vicinity ofthe site and visual textural classification of the on- site soils which are anticipated to be at subgrade elevation. Site Area Traffic Index Pavement Section Driveway and Parking s4.0 3.0" Asphaltic Concrete Areas for Autos and Light over 4.0" Aggregate Base Weight Vehicles, Only. over properly prepared subgrade Asphalt concrete pavement materials should be as specified in Section 39 of the current CALTRANS Standard Specifications. or an equivalent substitute. Aggregate base should conform to Class 2 material as specified in Section 26-1.02B of the current CALTRANS Standard Specifications or an equivalent substitute. Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 30 The subgrade soil, including utility trench backfill, should be compacted to 90 percent or greater relative compaction to a depth of 1:0 foot or greater. The aggregate base material 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 the Marshall compacted laboratoiy sample per current ASTM D 1559 procedures. If pavement subgrade soils are prepared at the time of rough grading of the building site and the areas are not paved immediately, additional obseivations and testing will have to be performed before placing aggregate base material or asphaltic concrete to locate areas that may have been damaged by construction traffic, construction activities, and/or seasonal wetting and drying. In the proposed pavement areas, soil samples should be obtained at the time the subgrade is graded for R -Value testing according to California Test Method 301 procedures to verify the pavement design recommendations. 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. The longevity and performance of pavements utilizing aggregate base material for support is dependent upon the quality of the material. CALTRANS specifications do not specifically exclude the use of material other than anatural, crushed rock and rock dust for Class 2 Aggregate Base material as the Standard Specifications for Public Works Construction, Section 200-2.2, does for Crushed Aggregate Base material. Often times, reclaimed PCC concrete, HMA concrete, bricks, concrete blocks, etc. are crushed and graded to produce a Class 2 Aggregate Base material per CALTRANS specifications: However, gradation is not the only quality Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 31 control for aggregate base material. If a reclaimed material is proposed for use on the project, the materials should be tested for the following quality requirements per the appropriate CALTRANS procedures: TEST QUALITY REQUIREMENT Resistance (R -Value) 78 Minimum Sand Equivalent 25 Minimum Durability Index 35 Minimum Samples of the proposed reclaimed material should be sampled from the manufacturer's stockpiles 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 CALTRANS Standard Specifications, "No single aggregate grading or Sand Equivalent test shall represent more than 500 cubic yards or one days production, whichever is less." 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 fi-om adjacent water sources. Saturation of aggregate base and/or subgrade materials could result in pavement failure and/or premature maintenance. POST -GRADING CRITERIA Soils generated from the excavation of footings, utility trenches, swimming pools, 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 Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 32 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 property and should not change the distance from the weep screed on the structure to the finished adjacent soil gradeper the recommendations presented in the `Finish Lot Drainage Recommendations' section of this report. UTILITY TRENCH RL COMMENDATIONS 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 soil. 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 soil. 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 1:1 plane projected downward from the outside bottom edge of the adjacent footing unless the utility lines are designed for the footing surcharge loads: It is recommended that utility trench excavations be designed and constructed in accordance with 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 soil types encountered. Trenches over 20 feet in vertical depth should be designed by the Contractor's engineer based on site specific geotechnical analyses. For planning purposes, we recommend that the following OSHA soil type designations be used: TEMPORARY EARTH OSHA SLOPE MATERIAL'TYPE* INCLINATION (H: V) Undocumented Fill C Compacted Fill C 1.S:I Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 33 Type `C' Granular soils including gravel, sand, and loamy sandy. ** 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. Upon making the excavations, the soil classifications and excavation performance should be confirmed in the field by a competent person in accordance with OSHA regulations. Excavations of less than 5.0 feet in depth may also be subject to collapse due to water, vibrations, previously disturbed soils, 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 person 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 the vertical depth of the excavation. Excavations should be initially observed by the project Geotechnical Consultant and/or his representative to verify the recommendations presented or to make additional recommendations 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 by the project Geotechnical Consultant or his representative. Deep utility trenches may experience caving which will require special considerations to stabilize the wails and expedite trenching TEMPORARY EARTH OSHA SLOPE MATERIAL SOH' INCLINATION TYPE* �.V)** Alluvium C 1.5:1 Type `C' Granular soils including gravel, sand, and loamy sandy. ** 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. Upon making the excavations, the soil classifications and excavation performance should be confirmed in the field by a competent person in accordance with OSHA regulations. Excavations of less than 5.0 feet in depth may also be subject to collapse due to water, vibrations, previously disturbed soils, 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 person 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 the vertical depth of the excavation. Excavations should be initially observed by the project Geotechnical Consultant and/or his representative to verify the recommendations presented or to make additional recommendations 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 by the project Geotechnical Consultant or his representative. Deep utility trenches may experience caving which will require special considerations to stabilize the wails and expedite trenching Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 - April 23, 2007 Page 34 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. Backfill material should be placed in a lift thickness appropriate for the type of backfill material and compaction equipment used. Backfill material should be 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 SITE DRAINAGE RECOMIIWNDATIONS Positive drainage should be established away from the tops of slopes, the exterior walls of structures, the back of retaining walls, and decorative concrete block perimeter walls. Finish surface gradients in unpaved areas should be provided next to tops of slopes and buildings to guide surface water away from foundations and slabs 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 property should be determined by the project Structural Engineer designing the foundations and slabs in conjunction with the project Civil Engineer designing the precise grading for site drainage, respectively, in accordance with the 2001 CBC and the soil types -and expansion characteristics for the soils 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 2001 CBC. Landscape plants with high water needs and trees should be planted at a distance away from the structure equal 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 Retail Center - La Quinfa, California Washington Street & Calle Tampico Project No.: 060191 - April 23, 2007 Page 35 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 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 soils underling the buildings. Separately constructed planters with solid bottoms, independent of the underlying soil, 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. PLAN AND SPECIFICATION REVIEW Subsequent to formulation of finish plans and specifications for the project, but before bids for construction are requested, it is recommended that the project Geotechnical Consultant be provided the opportunity for a general review of the completed rough grading and foundation plans for the proposed development to verify compatibility with site geotechnical conditions and so that earthwork, foundations, slab -on -grade, pavement, etc. recommendations presented in this report may be properly interpreted and implemented in the plans and specifications. conformance with the recommendations contained in this report. If the project Geotechnical Consultant is not accorded the opportunity to make the recommended review, we will not assume responsibility for misinterpretation of the recommendations presented in this report. c Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 36 PRE-BID CONFERENCE It is recommended that a pre-bid conference be held. with the owner or an authorized representative, the project Architect, the project Civil Engineer, the project Geotechnical Consultant, and the proposed contractors present. This conference will provide continuity in the 77 bidding process and clarify questions relative to the grading and -construction requirements of the project. PRE -GRADING CONFERENCE Before the start of grading, a conference should be.held with the owner or an authorized representative, the contractor, the project Architect, the project Civil Engineer, and the project Geotechnical Consultant present. The purpose of this meeting should be to clarify questions relating to the intent of the grading recommendations and to verify that the project specifications comply with the recommendations of this Geotechnical Consulting report. Special grading procedures and/or difficulties proposed by the contractor can also be discussed at that time. CONSTRUCTION OBSERVATIONS AND TESTING Rough grading of the property should be performed under engineering observation and testing performed by the project Geotechnical Consultant. Rough grading includes, but is not limited to, overexcavation cuts, fill placement, and excavation of temporary and permanent cut and fill slopes. In addition, the project Geotechnical Consultant should observe the foundation excavations. Observations should be made before installation of concrete forms and/or reinforcing steel to verify and/or modify the conclusions and recommendations in this report. Observations of finish grading, utility or other trench backfill, pavement subgrade and base course, retaining wall backfill, slab presaturation, or other earthwork completed for the subject development should also be performed by the project Geotechnical Consultant. This is to Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 37 observe compliancewitlrthe design concepts, specifications, and/or recommendations and allow design changes in the event subsurface conditions differ from those anticipated prior to the start of construction. If the observations and testing to verify site geotechnical conditions are not performed by the project Geotechnical Consultant, liability for the performance of the development is limited to the actual portions of the project observed and/or tested by the project Geotechnical Consultant If parties other than the project Geotechnical Consultant are engaged to perform soils and materials observations and testing, they should be notified that they will have to assume total responsibility for the geotechnical aspects of the project by concurring with the recommendations in this report or providing alternative recommendations, per Section 3317.8 of the Appendix to Chapter 33, "Transfer of Responsibility," in the 2001 CBC. Neit er the presence of the project Geotechnical Consultant and/or his field representative, nor the field observations and testing, should excuse the contractor for defects discovered in the contractor's work. The project Geotechnical Consultant and/or his representative should not be responsible for j ob or project safety. Job or project safety should be the sole responsibility of the contractor. CLOSURE This report has been prepared for use by the parties or project named or described in this document. It mayor may not contain -sufficient information for other parties or purposes. -In the event that changes in the stated nature, design, or location of the proposed development and/or structures as described in this report are planned, the conclusions and recommendations contained in this report will not be considered valid unless the changes are reviewed and the conclusions and recommendations of this report modified or verified in writing. This report is not intended for use as a bid document. Persons or companies using this report for bidding or construction purposes should perform such independent studies and explorations as they deem v adequate to satisfy themselves as to the surface and subsurface conditions to be encountered and the procedures to be used in the performance of their work on this project. Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page. 38 APPENDIX I DRAWINGS Figure No. 1, `Site Location Map.' Figure No. 2, `Preliminary Site Plan with Boring Locations.' SITE LOCATION PLAN HEIDER ENGINEERING SERVICES, INC. 800-A SOUTH ROCHESTER AVE. - ONTARIO, CA 91761 Phone: 909-673-0292 - Fax: 909-673-0272 - U I 36 8OO-A SOUTH ROCHESTER AVE - ONTARIO, CA 91761 Phone: 909-673-0292 Fax: 909-673-0272 BORING LOCATION • PLAN e�mn+o PAno+a la7 gg 1Wtd61t lOaM 1� �G rt0 � � b �... Ul M11�Y � 0MM w . • - � Im✓.� pmtM gKNN 9 RET L SHOPS a ( zi O 0 C-1 ,. ,.•.,r Ee sF` 'Z 13, _r amew - Z w 1 �yaQn wua m .1 t" 1 tr T �./ tad mna wn — 'CALLE ---- — �-- PI TAMCO MILBEM MPA OF NIC •'230 =tR ancw^�.'mDG6F` PARCEL 3UMMAPY IW M 1704 300KlnrMQ$Q2 A 16 SITE 5■if1`61G ,�.mm3o•Pc O M0AMA.M OTS OO.PE 6 P 84 APK: 7nm6am UgARA trxrz:PLAN 7+mo . AM rA-400 rL u}pQJJC AfW - {30 00. i ARcB Tm pyANNING ipso W� CW-.& MIS,d00 peudeaP. GllfacoL 91105 Po= 616/7%4961 Rpta Stwpe et LAVII=A NWO CW T� b O�mo 3051 flNl.. Otl�l8i0 WE PLAN SD1 PSdAP�ARr RCTAIL 4WP5 / U MJ TA W-L/k C Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 39 APPENDIX II SOIL BORING LOGS B-1 through B- 3 Test Hole No.: B-1 Drilling Date: 4/8/2007 loose Drilling Method: Hollow stem auger Project Number: 060191 6.7 6 SM 100 27 20 SAMPLE DATA SPT 6.4 11 SM 100. 19 Grey brown fine SAND, some silt SOIL DESCRIPTION % Passin 25 SPT 12.5 8 ML -SM 100 94 Light brown SILT, trace sand, loose moist a o Uj m Ui SPT w 7)g 9 SM o o z Tan SILT, some fine sand, loose, moist 35 C z D Q vCL ML -SM 97 89 U)O SPT Z 7 ML -SM 100 95 0 2.5 Light brown fine sandy SILT, loose SPT 8.5 5 SM 100 70 moist 5 loose SPT 13.0 6 SM 100 70 7.5 SPT 10.4 8 SM 99 60 Brown sandy SILT, loose, moist 10 SPT 8.6 6 SM 100 42 Grey brown silty SAND, loose, moist 15 loose SPT 6.7 6 SM 100 27 20 SPT 6.4 11 SM 100. 19 Grey brown fine SAND, some silt medium dense, moist 25 SPT 12.5 8 ML -SM 100 94 Light brown SILT, trace sand, loose moist 30 Brown sandy SILT, loose, moist SPT 12.0 9 SM 100 65 Tan SILT, some fine sand, loose, moist 35 _ SPT 13.5 8 ML -SM 97 89 SPT 14.5 7 ML -SM 100 95 40 loose, moist Boring Terminated at 41.5 feet No groundwater encountered during 45 drilling or after removal of augers 50 Test Hole No.: B-2 Drilling Date: 4/8/2007 Drilling Method: Hollow stem auger Project Number: 060199 SAMPLE DATA SOIL DESCRIPTION % Passin o � a o w D vi U) g a H m Z W h Q U w 4 o n Q �' } O i Z 0 0 2.5 Light brown sandy SILT, loose, slightly CRS 99.3 5.8 13 SM moist 5 moist CRS 97.4 13.0 12 SM 7.5 Grey brown sandy SILT, loose, slightly CRS 100.9 5.6 23 SM moist 10 CRS 92.3 4.5 15 SM Grey brown silty SAND, loose, slightly moist 15 Grey brown fine silty SAND, loose, CRS 97.4 4.5 20 SM slightly moist 20 Light brown fine SAND, some silt, loose, CRS 95.0 6.1 21 SM moist Boring Terminated at 21.5 feet No groundwater encountered during 25 drilling or after removal of augers 30 35 40 45 50 Test Hole No.: B-3 Drilling Date: 4/8/2007 Drilling Method: Hollow stem auger Project Number: 060191 SAMPLE DATA SOIL DESCRIPTION % Passin J J CLU W W D co 2 m 0 Z � Q U 0 aa. Ui Q } < WO O Z c� � g O O 2.5 Light brown sandy SILT, loose CRS 96.6 25.9 22 SM very moist 5 moist CRS 106.0 6.0 16 SM 7.5 Light brown sandy SILT, loose, slightly CRS 100.8 3.5 28 SM moist 10 CRS 94.2 8.6 18 SM Grey brown silty SAND, loose, moist 15 loose, slightly moist CRS 95.8 3.8 22 SM .20 Grey brown fine SAND, some silt, CRS 100.2 6.1 30 SM medium dense, moist Boring Terminated at 21.5 feet No groundwater encountered during 25 drilling or after removal of augers 30 35 I 40 45 50 Retail Center - La Quinta, California Washington Street & Calle Tampico Project No.: 060191 April 23, 2007 Page 40 APPENDIX III . LABORATORY TEST RESULTS Maximum Diy Density / Optimum Moisture Content . Relationship Test Report Consolidation Test Reports Direct Shear Test Reports Laboratory Compaction Characteristics of Sdil Using Modified. Effort, ASTM D 1557 Tested For: Mr. Dan Almquist Project: Retail Center -Washington & Calle Tampico The Foundation Group La Quints, California 3857 Birch Street, Ste. 496 Newport Beach, CA 92660 Date: April 10, 2007 Helder Engineering File No.: 060191-4 Lab Sample No.: 138 Visual Class.: Light brown fine sandy SILT Test Results: Sample'Source: B-2 @ 0 to 5 feet Maximum Dry Density, pcf: - 116.5 i 'Method of Test: ASTM D 1557, Method A Optimum Moisture Content, %: 13.0 is 150 146 142 138 134 i 130 o ,126 122 d o G 1.18 114 110 .106 102 98 94 Maximum Density - Optimum Moisture Content, ASTM D 1557 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Moisture Content, % fah: (909) 673-0292 FAX: (909) 673-0272 . . 800-R South Rochester Ave., Ontario CA 91761 81 71 Tested For: Mr. Dan Almquist Project: Retail Center - Washington & Calle Tampico The Foundation Group - La Quinta, California 3857 Birch Street, Ste. 496 Newport Beach, CA 92660 G Date: April 13, 2007 Heider Engineering File No.: 060191-5 0.01 - Consolidation Test B-2 @ 0 to 5 feet Remolded to 90% relative compaction Pressure, kips per square foot 0.1 1 10 4 5 6 Ph: (909) 673-0292 FAX: (909) 673-0272 800-A South Rochester Ave,, Ontario CA 91 761-81 71 •,� /p �p �e d Tested For: Mr. Dan Almquist Project: , Retail Center - Washington & Calle Tampico 'The Foundation Group La Quinta, California 3857 Birch Street, Ste. 496 Newport Beach, CA 92660 Date: April 13, 2007 Heider Engineering File No.: 060191-6 :i Consolidation Test B-3 @ 5 feet Tested at Insitu density 108 pcf Pressure, kips per square foot 0.01 0.1 1 10 0 1 2 c 0 m 'o 0 0 3 U L d 0. 4 5 6 Ph: (909) 673-0292 FAX: (909) 673-0272 800-R South Rochester Ave., Ontario Cid 91761 -81 71 Tested For: Mr. Dan Almquist Project: Retail Center - Washington & Calle Tampico The Foundation Group La Quinta, California 3857 Birch Street, Ste. 496 Newport Beach, CA 92660 Date: 4/13/07 Heider Engineering File No.: 060191 Lab Sample No.: 138 { Sample tested remolded to 90% relative compaction Dry Density: 105 pcf Moisture Content: 13.0% Visual Classification: Light brown fine sandy SILT Test Results: Sample Source: B-2, 0 to 5 feet 95 Angle, degrees: 28 Method of Test: Direct Shear Cohesion, c, psf: 145 2500 2000 w N CL 500 0+ 0 Direct Shear Test 500 1000 1500 2000 2500 3000 3500 . 4000 4500 Normal Stress, psf J Ph: (909) 673-0292 FAX: (909) 673-0272 800-R South Rochester Ave., Ontario CA 91 761-81 71 C4Ei Tested For: Mr. Dan Almquist Project: Retail Center - Washington & Calle Tampico The Foundation Group La Quinta, California 3857 Birch Street, Ste. 496 Newport Beach, CA 92660 Date: 4/13/07 Heider Engineering File No.: 060191-3 Lab Sample No.: 138 Sample tested undisturbed, saturated, drained Dry Density: 104 pcf Moisture Content: 5.6% Visual Classification: Light brown fine sandy SILT Test Results: Sample Source: B-2, 2.5 feet Angle, degrees: 25 Method of Test: Direct Shear Cohesion, .c, psf: 225 2500 2000 a t 1500 500 04 0 Direct Shear Test JVV IVVV IVVV LVVV LJYV JVVV JJVV `IVVV YV VU Normal Stress, psf Ph: (909) 673-0292 FAX: (909) 673-0272 800-R South Rochester Ave., Ontario CR 91761-8171 al W ,f4E� Tested For: Mr. Dan Almquist Project: Retail Center - Washington & Calle Tampico The Foundation Group La Quinta, California 3857 Birch Street, Ste. 496 Newport Beach, CA 92660 Date: 4/13/07 Heider Engineering File No.: 060191-2 Lab Sample No.: 138 Sample tested undisturbed, saturated, drained Dry Density: 107 pcf Moisture Content: 6.0% Visual Classification: Light brown fine sandy SILT Test Results: Sample Source: B-2, 5 feet (� Angle, degrees: .26 Method of Test: Direct Shear Cohesion, c, psf: 140 Direct Shear Test 500 0+ 0 500 1000 1500 2000 2500 3000 3500 4000 4500 Normal Stress, psf Ph: (909) 673-0292 FAX: (909) 673-0272 800-A South Rochester Ave., Ontario CA 91 761-81 71 2500 2000 w • N a $ 1500 rn .c .91 1000 r 500 0+ 0 500 1000 1500 2000 2500 3000 3500 4000 4500 Normal Stress, psf Ph: (909) 673-0292 FAX: (909) 673-0272 800-A South Rochester Ave., Ontario CA 91 761-81 71