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Home My WebLink AboutSDP 12-01; VISTA LA COSTA RESIDENTIAL DEVELOPMENT; LIMITED GEOTECHNICAL INVESTIGATION; 2012-03-02111001-1 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 (619) 258-7901 Fax 258-7902 Diversified Development 24335 Prielipp Road , Suite 112 Wildomar, California 92595 Subject: Limited Geotechnical Investigation Vista La Costa Residential Development Lots 21 & 22 Gibraltar Street APN 216-290-20, 21 & 216-290-47 Carlsbad, California 92009 Ladies & Gentlemen: ½ L:(;1 4..1- 1)/4 ;l March 2, 2012 Project No. 12-1147H I d5c)e roj In accordance with your request, we have performed a limited geotechnical investigation at the subject site to discuss the geotechnical aspects of the project and provide recommendations for the proposed development. Our investigation has found that the proposed building pads are underlain by topsoil, undocumented fill and alluvium to depths ranging from approximately 7 to 15 feet below existing grades. These soils were underlain by dense sandstone/claystone of the Santiago Formation to the explored depth of 17 feet. It is our opinion that the development of the proposed residential project is geotechnically feasible provided the recommendations herein are implemented in the design and construction. Should you have any questions with regard to the contents of this report, please do not hesitate to contact our office. Respectfully submitted, No. GE 2704 Exp: -'-'> ,P.E. RCE 54071, GE 2704 MSD\md 6sP ic/ Pl2&, C RSJFIED DEl PMENT/ VISTA LA COS 'ROJECTNO. 147H/ TABLE OF CONTENTS INTRODUCTION.......... .................................................................................................................................... 3 SCOPEOF SERVICES.....................................................................................................................................3 SITE DESCRIPTION AND PROPOSED CONSTRUCTION ......................................................................... 3 FIELD INVESTIGATION AND LABORATORY TESTING.......................................................................4 GEOLOGY.......................................................................................................................................................... 4 GeologicSetting....................................................................................................................................4 SiteStratigraphy....................................................................................................................................4 SEISMICITY......................................................................................................................................................5 RegionalSeismicity..............................................................................................................................5 SeismicAnalysis...................................................................................................................................5 2010 CBC Seismic Design Criteria .......................................................................... . ........................... 6 Geologic Hazard Assessment...............................................................................................................6 GEOTECHNICAL EVALUATION .................................................................................................................7 CompressibleSoils ........................................................... ...................................................................... 7 ExpansiveSoils ..................................................................................................................................... 7 Groundwater..........................................................................................................................................7 CONCLUSIONS AND RECOMMENDATIONS ...........................................................................................8 GRADINGAND EARTHWORK.....................................................................................................................8 Clearingand Grubbing..........................................................................................................................8 StructuralImprovement of Soils...........................................................................................................8 Transitions Between Cut and Fill.........................................................................................................9 Method and Criteria of Compaction ................................................................................... . ................. 9 ErosionControl ........................................................................................................................ ............. 9 StandardGrading Guidelines................................................................................................................9 FOUNDATIONSAND SLABS......................................................................................................................10 SETTLEMENT................................................................................................................................................10 PRESATURATION OF SLAB SUBORADE ................................................................................................ 10 RETAININGWALLS ..... . ................................................................................................................................ II TEMPORARYSLOPES .................................................................................................................................. I I TRENCHBACKFILL ..................................................................................................................................... 11 DRAINAGE.....................................................................................................................................................12 FOUNDATIONPLAN REVIEW...................................................................................................................12 LIMITATIONS OF INVESTIGATION ........................................................................................................12 ADDITIONALSERVICES ............................................................................................................................13 PLATES Plate 1- Location of Exploratory Boreholes Plate 2 - Summary Sheet (Exploration Borehole Logs) Plate 3 - USCS Soil Classification Chart PAGE L-I, LABORATORY TEST RESULTS .............................................................................................17 REFERENCES.................................................................................................................................................. 18 2 :RSIFIED DEI 'PMENT/ VISTA LA COS ROJECTNO. 147H1 INTRODUCTION This is to present the findings and conclusions of a limited geotechnical investigation for the proposed construction of three 3-story residential buildings over basement garages to be located on the north side of Gibraltar Street, in the City of Carlsbad, California. The objectives of the investigation were to evaluate the existing soils conditions and provide recommendations for the proposed development. SCOPE OF SERVICES The following services were provided during this investigation: Site reconnaissance and review of published geologic, seismological and geotechnical reports and maps pertinent to the project area Subsurface exploration consisting of five (5) test pits within the limits of the proposed area of development. The test pits were logged by our Staff Geologist. O Collection of representative soil samples at selected depths. The obtained samples were sealed in moisture-resistant containers and transported to the laboratory for subsequent analysis. Laboratory testing of samples representative of the types of soils encountered during the field investigation Geologic and engineering analysis of the field and laboratory data, which provided the basis for our conclusions and recommendations 0 Production of this report, which summarizes the results of the above analysis and presents our findings and recommendations for the proposed development SITE DESCRIPTION AND PROPOSED CONSTRUCTION - The subject site which comprises two lots (Lots 21 and 22) is located on the north side of Gibraltar Street, in the City of Carlsbad, California. The• vacant property encompasses an area of approximately 38000 square feet. The lots were graded into two terraced pads with an elevation difference of approximately 6 feet. Vegetation consisted of grass, shrub and a few trees. Site boundaries include Gibraltar Street to the south, residential parcels to the west and east and La Costa Golf Course to the north. The revised drawings prepared by O'Day Consultants of Carlsbad, California indicate that the proposed construction will include three residential buildings. It is our understanding that the structures will be three-story over basement garages. Associated improvements will include asphalt concrete and pervious pavements, a concrete sidewalk, landscaping and other appurtenances. RS!FFED DEI PMENT/ VISTA LA COS ROJECTNO. '4711! FIELD INVESTIGATION AND LABORATORY TESTING On February 22, 2012, five (5) test pits were excavated to a maximum depth of approximately 17 feet below existing grade with a Case CX 135 trackhoe. The approximate locations of the test pits are shown on the attached Plate No. 1, entitled "Location of Exploratory Test pits". A continuous log of the soils encountered was recorded at the time of excavation and is shown on Plate No. 2 entitled "Summary Sheet". The soils were visually and texturally classified according to the filed identification procedures set forth on Plate No. 3 entitled "USCS Soil Classification". Following the field exploration, laboratory testing was performed to evaluate the pertinent engineering properties of the foundation materials. The laboratory-testing program included moisture and density, maximum dry density and optimum moisture content, particle size analysis, Atterberg limits and expansion index tests. These tests were performed in general accordance with ASTM standards and other accepted methods. Page L-1 and Plate No. 2 provide a summary of the laboratory test results. GEOLOGY Geologic Setting The subject site is located within the southern portion of what is known as the 'Peninsular Ranges Geomorphic Province of California. The geologic map pertaining to the area indicates that the site is underlain by sandstone/claystone of the Santiago Formation (Tsa). Site Stratigraphy The subsurface descriptions provided are interpreted from conditions exposed during the field investigation and/or inferred from the geologic literature. Detailed descriptions of the subsurface materials encountered during the field investigation are presented on the exploration logs provided on Plate No. 2. The following paragraphs provide general descriptions of the encountered soil types. Topsoil Topsoil is the surficial soil material that mantles the ground, usually containing roots and other organic materials, which supports vegetation. Topsoil was observed in all test pits with a thickness of approximately 6 inches. It consisted of dark brown, silty sand that was damp to moist, loose and porous in consistency with some organics (roots and rootlets). Undocumented Fill (Ouf) Undocumented fill soils were encountered below the topsoil with a thickness ranging from approximately 2 to 7 feet. They generally consisted of reddish brown, clayey sand with gravel that was moist and medium dense in consistency. 4 L RS!F!ED DE PMENT/ VISTA LA COS ROJECTiVO. Alluvium (Oal) Alluvium was underlying the fill with a thickness ranging between approximately 5 and 10 feet. The material generally consisted of dark brown, sandy clay/ clayey sand with gravel that was moist to wet and soft to medium stiff in consistency. Santiago Formation (Tsa Sandstone/claystone of the Santiago Formation was encountered below the alluvium. The material generally consisted of light-colored clayey sand that was moist and dense in consistency. SEISMICITY Regional Seismicity Generally, Seismicity within California can be attributed to the regional tectonic movement taking place along the San Andreas Fault Zone, which includes the San Andreas Fault and most parallel and subparallel faults within the state. The portion of southern California where the subject site is located is considered seismically active. Seismic hazards are attributed to groundshaking from earthquake events along nearby or more distant Quaternary faults. The primary factors in evaluating the effect an earthquake has on a site are the magnitude of the event, the distance from the epicenter to the site and the near surface soil profile. According to the Fault-Rupture Hazard Zones Act of 1994 (revised'Alquist-Priolo Special Studies Zones Act), quaternary faults have been classified as "active" faults, which show apparent surface rupture during the last .11,000 years (i.e., Holocene time). "Potentially-active" faults are those faults with evidence of displacing Quaternary sediments between 11,000 to 16,000 years old. Seismic Analysis Based on our evaluation, the closest known "active" fault is the Rose Canyon Fault located approximately 7 miles (11 kilometers) to the west. The Rose Canyon Fault is the design fault of the project due to the predicted credible fault magnitude and ground acceleration. The Seismicity of the site was evaluated utilizing deterministic methods (Eqseach/ Eqfault ver 3.0, Blake, 2008) for active Quaternary faults within the regional vicinity. The site may be subjected to a Maximum Probable Earthquake of 6.9 Magnitude along, the Rose Canyon fault, with a corresponding Peak Ground Acceleration of 0.40g. The maximum Probable Earthquake is defined' as the maximum earthquake that is considered likely to occur within a 100-year time period. The effective ground acceleration at the site is associated with the part of significant ground motion, which contains repetitive strong-energy shaking, and which may produce structural deformation. As such, the effective or "free field" ground acceleration is referred to as the Repeatable High Ground Acceleration (RHGA). It has been determined by Ploessel and Slosson (1974) that the RHGA is approximately equal to 65 percent of the Peak Ground Acceleration for °RS!FIED DE PMENT/ VISTA LA COS ROJECTNO. 147H1 earthquakes occurring within 20 miles of a site. Based on the above, the calculated Credible RHGA at the site is 0.0.26g. 2010 CBC Seismic Design Criteria A review of the active fault maps pertaining to the site indicates the existence of the Rose Canyon Fault Zone approximately 11 km to the west. Ground shaking from this fault or one of the major active faults in the region is the most likely happening to affect the site. With respect to this hazard, the site is comparable to others in the general area. The proposed residential structures should be designed in accordance with seismic design requirements of the 2010 California Building Code or the Structural Engineers Association of California using the following seismic design parameters: 7. Site Class D Table 16 13.5.2 Mapped Spectral Acceleration For Short Periods, S 1.136 Figure 1613.5(3) Mapped Spectral Acceleration For a i-Second Period, S1 0.427 Figure 1613.5(4) Site Coefficient, F 1.046 Table 1613.5.3(1) Site Coefficient, F 1.573 Table 1613.5.3(2) Geologic Hazard Assessment Ground Rupture Ground rupture due to active faulting is not considered likely due to the absence of known fault traces within the vicinity of the project; however, this possibility cannot be completely ruled out. The unlikely hazard of ground rupture should not preclude consideration of "flexible" design for on-site utility lines and connections. Liquefaction Liquefaction involves the substantial loss .of shear strength in saturated soils, usually sandy soils with a loose consistency when subjected to earthquake shaking. Based on the absence of shallow groundwater and consistency of the underlying sandstone/claystone of the Santiago Formation, it is our opinion that the potential for liquefaction is very low. Landsliding There is no indication that landslides or unstable slope conditions exist on or adjacent to the project site. There are no obvious geologic hazards related to landsliding to the proposed development or adjacent properties. L RSIF!ED DE PMENT/ VISTA LA COS ROJECTNO. I 47H1 Tsunamis and Seiches The site is not subject to inundation by tsunamis due to its elevation and distance from the ocean. The site is also not subject to seiches (waves in confined bodies of water). GEOTECHNJCAL EVALUATION Based on our investigation and evaluation of the collected information, we conclude that the proposed construction is feasible from a geotechnical standpoint provided the recommendations provided herein will be properly implemented during structural development. In order to provide a uniform support for the proposed structures, overexcavation and recompaction of the structural portions of the building pads will be required. The foundations may consist of reinforced continuous and/ or spread footings with reinforced concrete slabs-on grade floors. Recommendations and criteria for foundation design are provided in the Foundation recommendations section of this report. Compressible Soils Our field observations and testing indicate low compressibility within the dense sandstone/claystone of the Santiago Formation, which underlies the site. However, loose topsoil, undocumented fill and alluvium were encountered to depths ranging from approximately 7 to 15 feet below existing grades. These soils are compressible and the alluvium is high1expansive. Due to the potential for soil compression upon loading, remedial and iing of these loose and expansive soils, including overexcavation and recompaction will be required. Following implementation of the earthwork recommendations presented herein, the potential for soil compression resulting from the new development has been estimated to be low. The low-settlement assessment assumes a well-planned and maintained site drainage system. Recommendations regarding mitigation by earthwork construction are presented in the Grading and Earthwork recommendations section of this report. Expansive Soils Expansion index tests were performed on representative samples of the fill and alluvium to determine volumetric change characteristics with change in moisture content. Expansion indexes of 33 and 151 were obtained respectively which indicates a low to very high expansion potential for the subgrade soils. Groundwater Static groundwater was not encountered to the depths of the test pits. The subject site is located at elevations between approximately 50 and 60 feet above Mean Sea Level. We do not expect groundwater to affect the proposed construction. Recommendations to prevent or mitigate the effects of poor surface drainage are presented in the Drainage section of this report. 7 L RSIFIED DE PMENT/ VISTA LA Cos: ROJECTNO. 47H1 CONCLUSIONS AND RECOMMENDATIONS The following conclusions and recommendations are based upon the analysis of the data and information obtained from our soil investigation. This includes site reconnaissance; field investigation; laboratory testing and our general knowledge of the soils native to the site. The site is suitable for the proposed residential development provided the recommendations set forth are implemented during construction. GRADING AND EARTHWORK Based upon the proposed construction and the information obtained during the field investigation, we anticipate that the proposed structures will be founded on continuous and/ or spread footings, which are supported by properly compacted fill. The following grading and earthwork recommendations are based upon the limited geotechnical investigation performed, and should be verified during construction by our field representative. Clearing and Grubbing All areas to be graded or to receive fill and/or structures should be cleared of vegetation. Vegetation and the debris from the clearing operation should be properly disposed of off-site. The area should be thoroughly inspected for any possible buried objects, which need to be rerouted or removed prior to the inception of, or during grading. All holes, trenches, or pockets left by the removal of these objects should be properly backfilled with compacted fill materials as recommended in the Method and Criteria of Compaction section of this report. Structural Improvement of Soils Information obtained from our field and laboratory analysis indicates that loose topsoil, undocumented fill and alluvium cover the building pads to depths of approximately 7 to 15 feet below existing grade. These subgrade soils are susceptible to settlement upon loading. Based upon the soil characteristics, we recommend the following: 4iUDpsei4rund1cumenIed fill n4aU i"m..shoiild he compIetJyremfwPr1 fro jjç 2p1umeLto_receb1e compacted fillsa ostructural-impravenients.. The bottom of the removal area should expose competent materials as approved by ECSC&E geotechnical representative. Prior to the placement of new fill, the bottom of the removal area should be scarified a minimum depth of6iric1ienche, moisture-conditioned within 2 percent above the optimum moisture content, and then recompacted to at least 90 percent relative compaction (ASTM D 15 57 test method). * Overexcavation should be completed for the structural building pads toaminimum det)th of 4 feet The limit of the required areas of overexcavation.ihould be extended a minimum of feet laterally beyond the perimeter footings (building footprints). RSIFIED DE PMENT/ VISTA LA COS ROJECTNO. 147H1 * Soils utilized as fill should be moisture-conditioned and recompacted in conformance with the following Method and Criteria of Compaction section of this report. The depth and extent of any overexcavation and recompaction should be evaluated in the field by a representative of ECSC&E. Transitions Between Cut and Fill The proposed structure is anticipated to be founded in properly compacted fill. Cut to fill transitions below the proposed structure should be eliminated during the earthwork construction as required in the previous section. Method and Criteria of Compaction Compacted fills should consist of approved soil material, free of trash debris, roots, vegetation or other deleterious materials. Fill soils should be compacted by suitable compaction equipment in uniform loose lifts of 6 to 8 inches. Unless otherwise specified, all soils subjected to recompaction should be moisture-conditioned within 2 percent over the optimum moisture content and compacted to at least 90 percent relative compaction per ASTM test method D1557. The on-site soils with the exception of the alluvium, after being processed to delete the aforementioned deleterious materials, may be used for recompaction purposes. The alluvium which is highly expansive should not be used as fill within at least 4 feet below basement grades. Should,any importation of fill be planned, the intended import source(s) should be evaluated and approved by ECSCE prior to delivery to the site. Care should be taken to ensure that these soils are not detrimentally expansive. Erosion Control Due to the granular characteristics of the on-site soils, areas of recent grading or exposed ground may be subject to erosion. During construction, surface water should be controlled via berms, gravel/ sandbags, silt fences, straw wattles, siltation' basins, positive surface grades or other method to avoid damage to the finish work or adjoining properties. All site entrances and exits must have coarse gravel or steel shaker plates to minimize offsite sediment tracking. Best Management Practices (BMPs) must be used to protect storm drains and minimize pollution. The contractor should take measures to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. After completion of grading, all excavated surfaces should exhibit positive drainage and eliminate areas where water might pond. Standard Grading Guidelines Grading and earthwork should be conducted in accordance with the standard-of-practice methods for this local, the guidelines of the current edition of the Uniform Building Code, and the requirements of the jurisdictional agency. Where the information provided in the geotechnical report differs from the Standard Grading Guidelines, the requirements outlined in the report shall govern. RSIFIED DE PMENT/ VISTA LA COS ROJECTNO. !47H1 FOUNDATIONS AND SLABS Continuous and spread footings are suitable for use and should extend to a minimum depth of 30 inches below the lowest adjacent grade for the proposed three-story structures over basement garages. Continuous footings should be at least 18 inches in width and reinforced with four #5 steel bars; two bars placed near the top of the footings and the other two bars placed near the bottom of the footings. Isolated or spread footings should have a minimum width of 24 inches. Their reinforcement should consist of a minimum of #5 bars spaced 12 inches-on center (each way) and placed horizontally near the bottom. The minimum reinforcement recommended is based on geotechnical considerations and is not intended to supercede the structural engineer requirements. Interior floor slabs for the basement garages should be a minimum 5-inch thick. Reinforcement should consist of #3 bars placed at 16 inches on center each way within the middle third of the slabs by supporting the steel on chairs or concrete blocks "dobies". The slabs should be underlain by 2 inches of clean sand over a 1 0-mil visqueen moisture barrier and a capillary break at least 2 inches thick, consisting of coarse sand, gravel or crushed rock not exceeding 3/4 inch in size with no more than 5 percent passing the #200 sieve. The effect of concrete shrinkage will result in cracks in virtually all-concrete slabs. To reduce the extent of shrinkage, the concrete should be placed at a maximum of 4-inch slump. The minimum steel recommended is not intended to prevent shrinkage cracks. An allowable soil bearing value of 2,000 pounds per square foot may be used for the design of continuous and spread footings at least 12 inches wide and founded a minimum of 12 inches into properly compacted fill soils as set forth in the 2010 California Building Code, Table 1804.2. This value may be increased by 400 psf for each additional foot of depth or width to a maximum value of 4,000 lb/ft2. Lateral resistance to horizontal movement may be provided by the soil passive pressure and the friction of concrete to soil. An allowable passive pressure of 250 pounds per square foot per foot of depth may be used. A coefficient of friction of 0.35 is recommended. The soils passive pressure as well as the bearing value may be increased by 1/3 for wind and seismic loading. SETTLEMENT Settlement of compacted fill soils is normal and should be anticipated. Because of the minor thickness of the fill soils anticipated under the proposed footings, total and differential settlements should be within acceptable limits. PRESATURATION OF SLAB SUBGRADE Due the granular characteristics and low expansion potential of the anticipated foundation soils, presoaking of subgrade prior to concrete pour is not required. However, subgrade soils in areas receiving concrete should be watered prior to concrete placement to mitigate any drying shrinkage, which may occur following site grading. 10 L RSIFIED DE PMENT/ VISTA LA cos: ROJECTNO. 47H1 RETAINING WALLS Cantilevered retaining walls should be designed for an "active" lateral earth pressure of 35 psfYft (35 pcf EFP) for approved granular and level backfill conditions. Where the walls support 2H: IV sloping backfill, the equivalent fluid pressure should be increased to 45 pcf. Cantilever walls subject to uniform surcharge loads should be designed for an additional uniform lateral pressure equal to one- third (1/3) the anticipated surcharge pressure. An additional lateral earth pressure due to earthquake motions of 25 pcf (EFP) may be applied using an inverted triangular distribution if required. Restrained walls such as basement walls should be designed utilizing an "at-rest" earth pressure of 60 psf7ft (60 pcf EFP) for approved granular and level backfill. Restrained walls subject to uniform surcharge loads should be designed for an additional uniform lateral pressure equal to one-half (1/2) the anticipated surcharge. Soil design criteria, such as bearing .capacity, passive earth pressure and sliding resistance as recommended under the Foundation and Slab Recommendations section, may be incorporated into the retaining wall design. Footings should be reinforced as recommended by the structural engineer and appropriate back drainage provided to avoid excessive hydrostatic wall pressures. As a minimum we recommend a fabric-wrapped crushed rock and perforated pipe syem. At least 2 cubic feet per linear foot of free- drainage crushed rock should be provided. N The remaining wall backfill should consist of approved granular material. This fill material should be compacted to a minimum relative compaction of 90 percent as determined by ASTM D-1557 test method. Flooding or jetting of backfill should not be permitted. Granular backfill should be capped with 18 inches (minimum) of relatively impervious fill to seal the backfill and prevent saturation. It should be noted that the use of heavy compaction equipment in close proximity to retaining structures can result in wall pressures exceeding design values and corresponding wall movement greater than that associated with active or at-rest conditions. In this regard, the contractor should take appropriate precautions during the backfill placement. TEMPORARY SLOPES For the excavation of foundations and utility trenches, temporary vertical cuts toamaximum height of 4.._feLIay..bconstructed in fill or natural soil. Any temporary cuts beyond the above height constraints shou115e shored or further laid back following a 1:1 (horizontal to vertical) slope ratio. OSHA guidelines for trench excavation safety should be implemented during construction. TRENCH BACKFILL Excavations for utility lines, which extend under structural areas should be properly backfihled and compacted. Utilities should be bedded and backfihled with clean sand or approved granular soil to a depth of at least one foot over the pipe. This backfill should be uniformly watered and compacted to a firm condition for pipe support. The remainder of the backfill should be on-site D ?SIFIED DEV 'MENT/ VISTA LA COS7 ?OJECT NO. . 47H1 soils or non-expansive imported soils, which should be placed in thin lifts, moisture-conditioned and compacted to at least 90% relative compaction. DRAINAGE Adequate measures should be undertaken to properly finish grade the site after the structure and other improvements are in place, such that the drainage water within the site and adjacent properties is directed away from the foundations, footings, floor slabs and the tops of slopes via rain gutters, downspouts, surface swales and subsurface drains towards the natural drainage for this area. A minimum gradient of 1 percent is recommended in hardscape areas. For earth areas, a minimum gradient of 5 percent away from the structure for a distance of at least 5 feet should be provided. Earth swales should have a minimum gradient of 2 percent. Drainage should be directed to approved drainage facilities. Proper surface and subsurface drainage will be required to minimize the potential of water seeking the level of the bearing soils under the foundations, footings and floor slabs, which may otherwise result in undermining and differential settlement of the structure and other improvements. FOUNDATION PLAN REVIEW Our firm should review the foundation plans during the design phase to assure conformance with the intent of this report. During construction, foundation excavations should be observed by our representative prior to the placement of forms, reinforcement or concrete for conformance with the plans and specifications. LIMITATIONS OF INVESTIGATION Our investigation was performed using the skill and degree of care ordinarily exercised, under similar circumstances, by reputable soils engineers and geologists practicing in this or similar localities. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report. This report is prepared for the sole use of our client and may not be assigned to others without the written consent of the client and ECSC&E, Inc. The samples collected and used for testing, and the observations made, are believed representative of site conditions; however, soil and geologic conditions can vary significantly between exploration trenches, boreholes and surface exposures. As in most major projects, conditions revealed by construction excavations may vary with preliminary findings. If this occurs, the changed conditions must be evaluated by a representative of ECSC&E and designs adjusted as required or alternate designs recommended. This report is issued with the understanding that it is the responsibility of the owner, or of his representative to ensure that the information and recommendations contained herein are brought to the attention of the project architect and engineer. Appropriate recommendations should be incorporated into the structural plans. The necessary steps should be taken to see that the contractor and subcontractors carry out such recommendations in the field. 12 U ?SIFIED DEE' 'MENT/ VISTA LA COS OJECTVO 47H1 The findings of this report are valid as of this present date. However, changes in the conditions of a property can occur with the passage of time, whether they are due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside of our control. Therefore, this report is subject to review and should be updated after a period of two years. ADDITIONAL SERVICES The review of plans and specifications, field observations and testing under our direction are integral parts of the recommendations made in this report. If East County Soil Consultation and Engineering, Inc. is not retained for these services, the client agrees to assume our responsibility for any potential claims that may arise during construction. Observation and testing are additional services, which are provided by our firm, and should be budgeted within the cost of development. Plates No. I through 3, Page L-I and References are parts of this report. 13 qrvV 7;7- p/7 / '\ /f ---\ 00, -\'-•t -i \ !I iI ei Ii ef EAST COUNTY SOIL CONSULTATION & ENGINEERING, INC. 10925 HARTLEY RD.. SUITE I. SANTRE. CA 92071 (619) 258-7901 FaA (619) 258-1902 P''A v*w//i9z At [;;g 4 -772iVc-'A e,rP/ae4'-7rey 77_ P175 A/ - 11 RSIFIED DE PMENT/ VISTA LA COS ROJECTNO. 147111 PLATE NO.2 SUMMARY SHEET TEST PIT NO. 1 DEPTH SOIL DESCRIPTION S y Surface TOPSOIL dark brown, damp to moist, loose, porous, silty sand with rootlets 0.5' UNDOCUMENTED FILL (Quf) reddish brown, moist, medium dense, clayey sand with gravel 2.0' it 11 " " it " 108.5 7.0' ALLUVIUM (Qal) dark brown, moist to wet, soft to medium stiff, sandy clay 103.6 12.0' dark brown, damp to moist, loose to medium dense, clayey sand 106.7 13.5' '' it it it if II it 113.6 15.0' SANTIAGO FORMATION (isa) light rcddish gray, moist, medium dense to dense, clayey sand with gravel 17.0' bottom of test pit, no caving, no groundwater, test pit backfilled and compacted with sheepsfoot roller 2/22/12 TEST PIT NO.2 DEPTH SOIL DESCRIPTION Y Surface TOPSOIL dark brown, damp to moist, loose, porous, silty sand with rootlets 0.5' UNDOCUMENTED FILL (QuO reddish brown, moist, medium dense, clayey sand with gravel 3• ' " " II 120.4 5.0' ALLUVIUM (Qal) dark brown, damp to moist, loose to medium dense, clayey sand 8.0' SANTIAGO FORMATION (isa) light reddish brown, moist, very dense, clayey sand with gravel refusal, bottom of test pit, no caving, no groundwater test pit backfilled with sheepsfoot roller 2/22/12 Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN % 14 M 15.9 20.6 14.8 11.6 7.6 .1.•. L RSIF!ED DE I PMEiVT/ VISTA LA COS ROJECTWO. °47H1 PLATE NO.2 (Continued) SUMMARY SHEET TEST PIT NO.3 DEPTH SOIL DESCRIPTION Y Surface TOPSOIL dark brown, damp to moist, loose, porous, silty sand with rootlets 0.5' UNDOCUMENTED FILL (QuO reddish brown, moist, medium dense, clayey sand with gravel 1.5' is ' " " " ' 113.7 2.0' ALLUVIUM (Qal) dark brown, moist to wet, soft to medium stiff, sandy clay 4.0' to "of 11 11 of " 105.8 7.0' SANTIAGO FORMATION (Isa) light reddish gray, moist, medium dense to dense, silty sand/ clayey sand with gravel 8.0' is It '' it it of ' 118.2 13.0' bottom of test pit, no caving, no groundwater test pit backfilled and compacted with sheepsfoot roller 2/22/12 TEST PIT NO.4 DEPTH SOIL DESCRIPTION Surface TOPSOIL dark brown, damp to moist, loose, porous, silty sand with rootlets 0.5' UNDOCUMENTED FILL (QuO reddish brown, moist, medium dense, clayey sand with gravel 2.0' ALLUVIUM (Qal) dark brown, moist to wet, soft to medium stiff, sandy clay 7.0' ft '' of of it of 102.0 8.0' dark brown, moist to wet, loose to medium dense, clayey sand with gravel 10.01 of 88.7 13.0' SANTIAGO FORMATION (Isa) light reddish brown, moist, dense, clayey sand with gravel 14.0' bottom of test pit, no caving, no groundwater test pit backfilled and compacted with sheepsfoot roller 2/22/12 Y= DRY DENSITY IN PCF M = MOISTURE CONTENT IN % 15 101 12.4 17.2 9.7 M 17.6 23.0 L RSIFIED DE PMENT/ VISTA LA cos: ROJECTiVO. 47H1 PLATE NO. 2 (Continued) SUMMARY SKEET TEST PIT NO.5 DEPTH SOIL DESCRIPTION Y M Surface TOPSOIL dark brown, damp to moist, loose, porous, silty sand with rootlets 0.5' UNDOCUMENTED FILL (QuO. reddish brown, moist, medium dense, clayey sand with gravel 3.0' ALLUVIUM (Qal) dark brown, moist to wet, soft to medium stiff, sandy clay 8.0' reddish brown, damp to moist medium dense, poorly-graded sand 110.1 7.8 13.0' SANTIAGO FORMATION (Tsa) light reddish gray, moist, medium dense to dense, silty sand/ clayey sand 14.0' bottom of test pit, no caving, no groundwater test pit backfihled and compacted with sheepsfoot roller 2/22/12 Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN % 16 CLASSIFICATION RANGE OF GRAIN SIZES U.S. STANDARD GRAIN SIZE IN SIEVE SIZE MILLIMETERS BOULDERS Above 12 Inches Above 305 COBBLES 12 Inches To 3 Inches 305 To 76.2 GRAVEL 3 Inches to No. 4 76.2 to 4.76 Coarse 3 Inches to '4 Inch 76.2 to 19.1 Fine 'I. Inch to No. 4 19.1 to 4.76 SAND No.4 to No. 200 4.76 to 0.074 Coarse No. 4 to No. 10 4.76 to 2.00 Medium No. 10 to No. 40 2.00 to 0.420 Fine No. 40 to No. 200 0.420 to 0.074 SILT AND CLAY I Below No. 200 Below 0.074 uI!....r..nht!._.Jn.i•..f I /1 1 7;L.zu/ - .t + .; - IIII /A?çi om H41 1I_ / - - I I I 4 -- 1 MAJOR vi VISIONS SYMBOL DESCRL --ON GW WELL GRADED GRAVELS OR GRAVEL- SAND MIXTURES. LITTLE OR NO FINES GRAVELS (MORE THAN /3 OF COARSE FRACTION *10.4 SIEVE GP ___________ POORLY GRADED GRAVELS OR GRAVEL-SAND MIXTURES, LITTLE OR NO FINES _________________________________ GM SILTY GRAVELS, GRAVEL-SAND-SILT MIXTURES COARSE GRAINED SOILS SIZE) CC CLAYEY GRAVELS, GRAVEL-SAND-CLAY MIXTURES (MORE THAN '/3 OF SOIL > NO: 200 SIEVE SIZE) sw WELL GRADED SANDS OR GRAVELLY SANDS, LITTLE OR NO FINES SANDS (MORE THAN OF COARSE FRACTION < NO. 4 SIEVE SP POORLY GRADED SANDS OR GRAVELLY SANDS. LITTLE OR NO FINES __________________________________ SM SILTY SANDS, SILT-SAND MIXTURES SIZE) SC CLAYEY SANDS, SAND-CLAY MIXTURES SILTS & IML INORGANIC SILTS AND VERY FINE SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PLASTICITY FINE GRAINED SOILS (MORE THAN OF SOIL <NO. 200 SIEVE SIZE) CLAYS LIQUID LIMIT <50 _________ CL __________ INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, OL ________ SILTY CLAYS, LEAN CLAYS ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY SILTS & MH INORGANIC SILTS. MICACEOUS OR DLATOMACEOUS FINE SANDY OR SILTY SOILS, ELASTIC SILTS CLAYS LIQUID LIMIT >50 • CH INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS _______________ OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTY CLAYS, ORGANIC SILTS HIGHLY ORGANIC SOILS Pt PEAT AND OTHER HIGHLY ORGANIC SOILS I I ULI IL!) SUIL CLASS!!' ICAT ION SYSTEM) (.iRAU4 SIZE CHART EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 PLASTICITY CHART DIVERSIFIED DEVELOPMENT PROJECT PROJECT NO. 12-1147111 ?ATE iSO. 3 MARCH 2, 2012 U.SC.S. SOIL CLASSIFICATION I RSIFIED DE P&fENT/ VISTA LA COS ROJECTNO. (47H1 PAGE L-1 LABORATORY TEST RESULTS MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557) The maximum dry density and optimum moisture content of the fill materials as determined by ASTM D1557, Procedures A and B which use 25 blows of a 10-pound slide hammer falling from a height of 18 inches on each of 5 equal layers in a 4-inch diameter 1/30 cubic foot compaction cylinder and Procedure C which uses 56 blows of a 10-pound slide hammer falling from a height of 18 inches on each of 5 equal layers in a 6-inch diameter 1/13.3 cubic foot compaction cylinder are presented as follows: OPTIMUM MAXIMUM MOISTURE SOIL TYPE/ DRY DENSITY CONTENT PROCEDURE DESCRIPTION (PCF) (%) LOCATION I/A REDDISH BROWN CLAYEY SAND 124.0 12.0 TP-1 @2.0' 2/A DARK BROWN CLAYEY SAND 125.0 10.4 TP-1 @ 14.0' EXPANSION INDEX TEST (ASTM D4829) INITIAL SATURATED INITIAL DRY MOISTURE MOISTURE DENSITY EXPANSION CONTENT(%) CONTENT(%) (PCF) INDEX LOCATION 11.1 23.3 106.7 33 TP-1 @2.0' 14.2 29.3 96.8 151 TP-1 @11.0' PARTICLE SIZE ANALYSIS (ASTM D422) U SitS an MOO- dard lrZ fll .1 f ' iiI11IiF I I 4t • ii. P,ercentJ'assingl iIiflj,7 . • '• Percent Passing t ;pf23 Che i' ) .f • 4 -4 .Fi1li',' . Percent Passing ' itiE -4fl) (3II 8 ,,p . •r .. ,. • AIIuvium,4l I PercentPassing* 101I1 .. 7 ( II. ... . i P1All1IvIumØifp 2" - 100 - - 1" 100 78 - 100 1/2" 96 61 - 93 3/8" 96 58 - 92 #4 96 52 • 100 88 #8 85 46 98 80 #16 78 37 87 65 #30 72 26 77 45 #50 62 16 68 24 #100 43 9 60 8 #200 31. 6 54 5 USCS SC SP-SC CL SW-SM 17 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 (619) 258-7901 Fax 258-7902 I AT .EEG LIMITS TEST RESULTS I DV&SIYIU TA LA COSTA PROJECT I CET NC. I O&T Th\ (=\ 12-1147}i1 13/2/12 ____•_) RSIF!ED DE PMENTJ VISTA LA COS ROJECTNO. 1 47H1 REFERENCES "2010 California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of 2", Published by International Code Council. "Eqfault/ Eqsearch, Version 3.0", by Blake, T.F., 2000, Updated 2008. "Limited Site Investigation, Proposed 26-Unit Apartment Complex, North Side of La Costa Avenue, West of Romeria Street, City of Carlsbad, California", Project No. 01-114701(1), Prepared by East County Soil Consultation and Engineering, Inc., Dated June 9,2001. "Geotechnical and Foundation Engineering: Design and Construction", by Robert W. Day, 1999. "1997 Uniform Building Code, Volume 2, Structural Engineering Design Provisions", Published by International Conference of Building Officials "Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada to be used with the 1997 Uniform Building Code", Published by International Conference of Building Officials. "Geologic Maps of the Northwestern Part of San Diego County, California", Department of Conservation, Division of Mines and Geology, by Siang S. Tan and Michael P. Kennedy, 1996. "Bearing Capacity of Soils, Technical Engineering and Design Guides as Adapted from the US Army Corps of Engineers, No. 7", Published by ASCE Press, 1994. "Foundations and Earth Structures, Design Manual 7.2", by Department of Navy Naval Facilities Engineering Command, May 1982, Revalidated by Change 1 September 1986. "Ground Motions and Soil Liquefaction during Earthquakes", by H.B. Seed and I.M. Idriss, 1982. 18