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Home My WebLink AboutCT 13-02; COASTAL 10; PRELIMINARY GRADING PLAN REVIEW; DWG 480-5, DWG 480-5A; 2013-03-19Mr. Brian Merritt Diversified Development EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 619 258-7901 FAX 619 258-7902 7668 El Camino Real, 104-280 Carlsbad, California 92009 Subject: Preliminary Grading Plan Review March 19, 2013 Project No. 12-1147G 1 Proposed 10-Unit Residential Development (Coastal Living 10) Lot 40 of La Costa South, Unit No. 1 Reference: Navarra Drive, Carlsbad, California 92009 "Limited Geotechnical Investigation, Proposed 10-Unit Residential Development (Coastal Living 10), Lot 40 of La Costa South, Unit No. 1, Navarra Drive, Carlsbad, California 92009", Project No. 12-1147G l, Prepared by East County Soil Consultation and Engineering, Inc., Dated January 10, 2013. Dear Mr. Merritt: In accordance with your request, we have reviewed the preliminary grading plan prepared by O'Day Consultants, Inc., to address the retaining walls adjacent to the bioretention basins for the proposed 10-unit residential project at the subject site. It is our understanding that the proposed bioretention basins will be constructed between the perimeter retaining walls and building foundations. We recommend that an adequate waterproofing sysytem be installed against the retaining walls and foundations because of the water storage of the bioretention basins. This may include a multilayered bituminous adhesive, a 10-mil plastic sheeting and a foam protection board. Mamadou Saliou Diallo, P.E. RCE 54071, GE 2704 MSD/md EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "l" SANTEE, CALIFORNIA 92071 (619) 258-7901 Fax 258-7902 Diversified Development, Inc. 7668 El Camino Real, 104-280 Carlsbad, California 92009 Subject: Limited Geotechnical Investigation January 10, 2013 Project No. 12-114701 Proposed 10-Unit Residential Development (Coastal Living 10) Lot 40 of La Costa South, Unit No. 1 Navarra Drive, Carlsbad, California 92009 Ladies & Gentlemen: 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 and slopewash to depths ranging from approximately 6 to 11 feet below existing grades. These soils were underlain by dense sandstone/ claystone of the Santiago Formation to the explored depth of 14 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, PLANCHEC Iii 0 ~ 0 w :c 0 COASTAL l!VING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-114701 TABLE OF CONTENTS INTRODUCTIOl\J .............................................................................................................................................. 3 SCOPE OF SER'/ICES ..................................................................................................................................... 3 SITE DESCRIPTION AND PROPOSED CONSTRUCTION ........................................................................ 3 FIELD INVESTIGATION AND LABO RA TORY TESTING ....................................................................... 4 GEOLOGY ......................................................................................................................................................... 4 Geologic Setting .................................................................................................................................... 4 Site Stratigraphy .................................................................................................................................... 4 SEISMICITY ...................................................................................................................................................... 5 Regional Seis111icity .............................................................................................................................. 5 Seis111ic ,\nalysis ................................................................................................................................... 5 20 IO CBC Seismic Design Criteria ...................................................................................................... 6 Geologic Hazard Assess1nent ............................................................................................................... 6 GEOTECHNICAL EVALUATION ................................................................................................................. 7 Con1pressible Soils ................................................................................................................................ 7 Expansive Soils ..................................................................................................................................... 7 Ground\vater .......................................................................................................................................... 7 CONCLUSIONS AND RECOMMENDATIONS ........................................................................................... 7 GRADING AND EARTHWORK ..................................................................................................................... 8 Clearing and Grubbing .......................................................................................................................... 8 Structural Improvement of Soils ........................................................................................................... 8 Transitions Between Cut and Fill. ........................................................................................................ 9 Method and Criteria of Compaction ..................................................................................................... 9 Erosion Control ..................................................................................................................................... 9 Standard Grading Guidelines ................................................................................................................ 9 FOUNDATIONS AND SLABS ........................................................................................................................ 9 SETTLEMENT ................................................................................................................................................ I 0 PRESA TURA noN OF SLAB SUBGRADE ................................................................................................ I 0 RETAINING W/\LLS ..................................................................................................................................... IO TEMPORARY SLOPES .................................................................................................................................. 11 TRENCH BACKFILL ..................................................................................................................................... 11 DRAINAGE ..................................................................................................................................................... 12 FOUNDATION PLAN REVIEW ................................................................................................................... 12 LIMITATIONS OF INVESTIGATION ........................................................................................................ 12 ADDITIONAL SERVICES ............................................................................................................................ 13 PLATES Plate I -Location of Exploratory Boreholes Plate 2 -Summary Sheet (Exploration Borehole Logs) Plate 3 -USCS Soil Classification Chart PAGE L-1, LABORATORY TEST RESULTS ............................................................................................. 16 REFERENCES ................................................................................................................................................. 17 2 COASTAL LIVING JO/DIVERSIFIED DEVELOPA1ENT PROJECT NO. 12-l 147GJ INTRODUCTION This is to present the findings and conclusions of a limited geotechnical investigation for the proposed construction of a 10-unit residential complex to be located on the south side of Navarra Drive, 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: 0 Site reconnaissance and review of published geologic, seismological and geotechnical reports and maps pertinent to the project area 0 Subsurface exploration consisting of four ( 4) test pits within the limits of the proposed area of development. The test pits were logged by our Staff Geologist. 0 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. 0 Laboratory testing of samples representative of the types of soils encountered during the field investigation 0 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 reconunendations for the proposed development. SITE DESCRIPTION AND PROPOSED CONSTRUCTION The subject site is located on the south side of Navarra Drive, in the City of Carlsbad, California. The vacant property encompasses an area of 21,303 square feet. The lot slopes moderately to the north. An approximately 9-foot high fill slope runs along the south side of the parcel. Vegetation consisted of grass, shrub and a few trees. Site boundaries include Navarra Drive to the north, similar residential developments to the west and east and La Costa Golf Course to the south. The preliminary site plan prepared by O'Day Consultants of Carlsbad, California indicates that the proposed construction will include a 10-unit residential complex. It is our understanding that the structures will be two and three-story, wood-framed and founded on continuous footings with slab- on-grade floors. Associated improvements will include a driveway, landscaping and other appurtenances. 3 COASTAL LIVING IOI DIVERSIFIED DEVELOPMENT PROJECT NO. J 2-l 147GJ FIELD INVESTIGATION AND LABORATORY TESTING On December 7, 2012, four (4) test pits were excavated to a maximum depth of approximately 14 feet below existing grade with a Link Belt 225 trackhoe equipped with a 24-inch bucket. 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 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 Settin_g 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 Fonnation (Tsa). Site Stratigrap!!Y 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 observed in the test pits was approximately 6 inches thick and consisted of dark brown, silty sand that was dry to moist, loose and porous in consistency with some organics (roots and rootlets). Slopewash (Qsw) Slopewash was underlying the topsoil with a thickness ranging between approximately 6 and 11 feet. The material generally consisted of reddish brown, sand with silt and gravel that was dry to moist and loose to medium dense in consistency. 4 COASTAL L!VJNG JOI DIVERSIFIED DEVELOPlv!ENT PROJECT NO. 12-114701 Santiago Formation (Tsa) Sandstone/claystone of the Santiago Formation was encountered below the slopewash. The material generally consisted of light-colored sandy clay that was moist and very stiff 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 10 kilometers (6.25 miles) 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 con-esponding 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 refen-ed 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 earthquakes occurring within 20 miles of a site. Based on the above, the calculated Credible RHGA at the site is 0.0.26g. 5 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO.12-1147GJ 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 10 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 complex 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: PARAMETER VALUE 2010 CBC REFERENCE Site Class D Table 1613.5.2 Mapped Spectral Acceleration For 1.148 Figure 1613.5(3) Short Periods, S, Mapped Spectral Acceleration For a 0.432 Figure 1613.5(4) I -Second Period, S 1 Site Coefficient, Fa 1.041 Table 1613.5.3(1) Site Coefficient, F v 1.568 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, type and consistency of the underlying bedrock materials, 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. Tsunamis and Seiches The site is not subject to inundation by tsunamis due to its elevation and distance to the ocean. The site is also not subject to seiches (waves in confined bodies of water). 6 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-1147GI GEOTECHNICAL 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 strnctural 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 and Slabs recommendations section of this report. Compressible Soils Our field observations and testing indicate low compressibility within the sandstone/claystone of the Santiago Formation and part of the slopewash, which underly the site. However, loose topsoil and slopewash were encountered to a depth of approximately 3 feet below existing grades. These soils are compressible. Due to the potential for soil compression upon loading, remedial grading of these loose 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 Soil.s Expansion index tests were performed on representative samples of the slopewash and formational soils to determine volumetric change characteristics with change in moisture content. Expansion indexes of 3 and 77 were obtained respectively which indicate a very low to medium 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 an elevation of approximately 100 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. 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 7 COASTAL LIVING JO/ DIVERSIFIED DEVELOPAfENT PROJECT NO. 12-1147Gl 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 infom1ation 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 perfom1ed, 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 and slopewash cover the site to a depth of approximately 3 feet below existing grade. These subgrade soils are susceptible to settlement upon loading. Based upon the soil characteristics, we recommend the following: * * * Subgrade soils to a minimum depth of 3 feet below existing grade should be completely removed from areas, which are planned to receive compacted fills and/or structural improvements. 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 of 6 inches, moisture- conditioned within 2 percent above the optimum moisture content, and then recompacted to at least 90 percent relative compaction (ASTM D 1557 test method). Overexcavation should be completed for the structural building pads to a minimum depth of 2 feet below the bottom of the proposed footings. The limit of the required areas of overexcavation should be extended a minimum of 5 feet laterally beyond the perimeter footings (building footprints). 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. 8 COASTAL LIVING IOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-1 !47Gl Transitions Between Cut and Fill The proposed structures are anticipated to be founded in properly compacted fill. Cut to fill transitions below the proposed structures 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 D 1557. The on-site soils, after being processed to delete the aforementioned deleterious materials, may be used for recompaction purposes. 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 \vith 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 infom1ation provided in the geotechnical report differs from the Standard Grading Guidelines, the requirements outlined in the report shall govern. FOUND A TIO NS AND SLABS a. Continuous and spread footings are suitable for use and should extend to a minimum depth of 24 inches below the lowest adjacent grade for the proposed two and three-story structures into the properly compacted fill soils. Continuous footings should be at least 18 inches in width and reinforced with four #4 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 #4 bars spaced 12 inches 9 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO.12-1147Gl on center (each way) and placed horizontally near the bottom. The mm1mum reinforcement recommended is based on geotechnical considerations and is not intended to supercede the structural engineer requirements. b. Interior concrete floor slabs 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 10-mil visqueen moisture barrier. 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. c. Where moisture sensitive floor coverings are anticipated over the slabs, the 10-mil plastic moisture barrier should be underlain by 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. d. 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. c. 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 of the 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. RETAINING WALLS Cantilevered retaining walls should be designed for an "active" lateral earth pressure of 35 psf/ft (35 pcf EFP) for approved granular and level backfill conditions. Where the walls support 2H: 1 V 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- 10 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-1 !47GJ 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 psf/ft ( 60 pcf EPP) 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. For earthquake motions, an additional lateral earth pressure of 35 pcf (EFP) may be applied using an inverted triangular distribution if required. 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 system. At least 2 cubic feet per linear foot of free- drainage crushed rock should be provided. 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 to a maximum height of 4 feet may be constructed in fill or natural soil. Any temporary cuts beyond the above height constraints should be 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 backfilled and compacted. Utilities should be bedded and backfilled 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 soils or non-expansive imported soils, which should be placed in thin lifts, moisture-conditioned and compacted to at least 90% relative compaction. 11 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-l 147Gl DRAINAGE Adequate measures should be undertaken to properly finish grade the site after the structures 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 structures 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 fom1s, reinforcement or concrete for conformance with the plans and specifications. LIMITATIONS OF INVESTIGATION Our investigation was perf 01med 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. 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 12 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-1147Gl 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 pai1s 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. 1 through 3, Page L-1 and References are parts of this report. 13 y .. } . ··'.:.---1' j' ~ ''• ... ~; :,..)",...,,,.. "":, ':" EAST COUNTY SOIL CONSULTATION & ENGINEERING, INC. 10925 HARTLEY RD .. SUITE I. SANTEE. CA 92071 (619) 258-790! Fax (619) 258-7902 \ J • I I ! -I ... ..,.,..., r I ··~-' >,r-,,.v ·-\ 1r_ :a, i 'It. ~ I I rr:. , ·-' I ' ; ; i , ... I ~ .,, ...... ' ··~ I DEPTH. Surface OS 2.0' 3.0' 4.5' 5.0' 7.0' 7.5' 9.0' DEPTH Surface 0.5' 3.0' 6.0' 8.0' 9.0' COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-114701 PLATEN0.2 SUMMARY SHEET TEST PIT N0.1 SOIL DESCRIPTION TOPSOIL dark brown, dry to moist, loose, porous, silty sand with rootlets SLOPEWASH (Qsw) reddish brown, dry to moist, loose to medium dense, sand with silt " becomes moist and medium dense abundant gravels SANTIAGO FORMATION (Tsa) light gray, moist to wet, medium dense to dense, sandstone/ claystone " " " bottom of test pit, no caving, no groundwater test pit backfilled and compacted with sheepsfoot roller 12/7 /12 TEST PIT NO. 2 SOIL DESCRIPTION TOPSOIL dark brown, dry to moist, loose, porous, silty sand with rootlets SLOPEWASH (Qsw) reddish brown, dry, loose, sand with silt and gravel becomes moist and medium dense SANTIAGO FORMATION (Tsa) light gray, moist to wet, medium dense to dense, sandstone/ claystone " bottom of test pit, caving in upper 3 feet, no groundwater test pit backfilled and compacted with sheepsfoot roller 12/7/12 y 119.7 131.3 105.9 y I 05.3 Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN % 14 M 5.6 8.5 15.4 M 17.9 DEPTH Surface 0.5' 4.0' 9.0' 11.0' DEPTH Surface 0.5' 3.0' 11.0' 14.0' COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-1147Gl PLATE NO. 2 (Continued) SUMMARY SHEET TEST PIT NO. 3 SOIL DESCRIPTION TOPSOIL dark brown, dry to moist, loose, porous, silty sand with rootlets SLOPEWASH (Qsw) y reddish brown, dry to moist, loose to medium dense, sand with silt and gravel becomes moist to wet and medium dense SANTIAGO FORMATION (Tsa) light reddish gray, moist, medium dense to dense, sandstone/ claystone bottom of test pit, no caving, no groundwater test pit backfilled and compacted with sheepsfoot roller 12/7/12 TEST PIT NO. 4 SOIL DESCRIPTION TOPSOIL dark brown, dry to moist, loose, porous, silty sand with rootlets SLOPEWASH (Qsw) y reddish brown, dry to moist loose to medium dense, sand with silt with gravel becomes moist to wet and medium dense SANTIAGO FORMATION (Tsa) light reddish gray, moist, medium dense to dense, sandstone/ claystone bottom of test pit, no caving, no groundwater test pit backfilled and compacted with sheepsfoot roller 12/7/12 Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN % 15 M M MAJOR DIVISIONS SThIBOL DESCRIPTION G'W WELL GRADED GRAVELS OR GRAVEL-SAND MIXTURES, LITTLE OR NO FINES GRAVELS GP (MORE THAN V, POORLY GRADED GRAVELS OR GRAVEL-SAND OF COARSE MIXTURES. UTILE OR NO FINES FRACTION GM >NO. 4 SIEVE SIL TY GRAVELS, GRAVEL-SAND-SILT MIXTURES SIZE) COARSE GC GRAINED SOILS CLAYEY GRAVELS, GRAVEL-SAND-CLAY MIXTURES (MORE THA.i"I !I: OF SOIL > S'\V I NO. 200 SIEVE SIZE) WELL GRADED SANDS OR GRA YELL Y SANDS, LITTLE OR NO FINES SANDS SP I (MORE THAN V, POORLY GRADED SA."IDS OR GR.-\ YELL Y SANDS, OF COARSE LITTLE OR NO FINES FRACTION SM I < NO. 4 SIEVE SILTY SANDS, SILT-SAND MIXTl.iRES SIZE) SC CLAYEY SANDS, SA."ID-CL\ Y MIXTURES ML I !NORGA.\/IC SIL TS AND VERY FINE SA.'<DS, ROCK SILTS & FLOCR. SIL TY OR CLAYEY FINE SA.'IDS OR CLAYEY SILTS WITH SLIGHT PL.\STICITY CLAYS CL I INORGANIC CLAYS OF LOW TO MED[UM LIQL:ID L!:Vf!T PL.\STICITY, GR..\ YELL Y CL<\ YS, SA.'IDY CLAYS, < 50 SIL TY CL.\ YS. LEAN CLAYS FINEGRUNED OL I SOILS ORGA.\/IC SILTS A.'iD ORGANIC SILTY CL-\ YS OF LOW PLASTICITY (MORE THAN V, OF SOIL< MH I NO. 200 SIEVE SIZE) INORGA.i\/IC SIL TS, MICACEOUS OR DIATOMACEOUS SILTS & FINE SA.t"IDY OR SIL TY SOILS, ELASTIC SILTS CLAYS CH I LIQUID LIMIT INORGA.t"IIC CL.\ YS OF HIGH PL.\STICITY, FAT > 50 CL.\YS OH I ORGANIC CL-\ YS OF MEDIUM TO HIGH PLASTICITY, ORGA.t"IIC SIL TY CL\ YS. ORGA."IIC SIL TS HIGHLY ORGA ... 'l"IC SOILS I Pt I P=AT A:"iD OTHB. HIGHLY ORGA."IIC SOILS CLASSIFICATION CHAR1' (CNIFIED SOIL CLASSIFICATION SYSTEM) CL..\SS!FIC.\ TION I R.\:'-iGE OF GR.\f.'< SIZES BOCLDE:RS COBBLES GR.\ VU C0ars~ Fine SA.'iD C0arsc I I I LS. ST..\:'-iDARD SIEVE SIZE Above 12 lnches 12 !nches To 3 Inch~s 3 Inches to '.'lo. -l J [nches ,o . , .nch '!, Inch to No. 4 , l/ ' No. 4 :o '.'lo. :?CO No. -l to No. 10 Medium No. l O to No. -10 Fine No. 40 to No. 200 SILT .\:'ID CL..\ Y I Below No. 200 GRAIN SIZE CH.-\RT I I I GR.\1:'i SIZE !;'Ii :'rlILLI:'>-!ETERS Above 305 305 To '.'6.: 76.2 to 4.76 ,6.-.o ,9 .• 19 l to -t 76 , , . ' ' .!. 76 :o •).)7 4 -l. 76 to 2.)0 2.·JO to O . .!ZO 0.420 :o ').'T .! Bdow O:J7.! EAST COUNTY SOIL CONSt:L TA TION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUTE "l" SANTEE, C..\LIFOR.;"(JA. 9:!0'71 C.S.C.S. SOIL CLASSIFICATIO~ 70 I I I 5Q I .. I ~ !O ~ I I -~ "' ~ I I ,_ ~ !Q I "' I I I ! ~ :~ ~ \ ~~~~H ,a 10 =~ !a 40 io ;a 70 30 iO ICO t..:cu:o ..;Mir :l:..:. -: PLASTICITY CHART COASTAL LIVING 10 PROJECT PROJECT :m. 12-il47Gl p;_,,\TE NO. 3 JAN. 10, 2013 COASTAL LIVING JOI DJVERS!FIED DEVELOPMENT PROJECT NO. !2-l 147Gl INITIAL MOISTURE CONTENT(%) 9.3 14.5 U.S. Standard Sieve Size 2'' I" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200 uses PAGE L-1 LABORATORY TEST RESULTS EXP ANSI ON INDEX TEST (ASTM D4829) SATURATED INITIAL DRY MOISTURE DENSITY EXPANSION CONTENT(%) (PCF) INDEX LOCATION 17.1 111.3 3 TP-2@3.0' 29.3 98.9 77 TP-2@8.0' PARTICLE SIZE ANALYSIS (ASTM D422) Percent Passing Percent Passing Percent Passing TP-3@6.0' TP-4@6.0' TP-2@8.0' Slopewash Slopewash Santiago Formation -- -100 - -83 - 100 77 - 99 63 100 95 40 99 81 17 98 48 8 96 16 5 93 8 4 87 6 " 79 .) SP-SM SW CL 16 ,' COASTAL l/VING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-1147G1 REFERENCES 1. "Limited Geotechnical Investigation, Vista La Costa Residential Development, Parcel 2 of Certificate of Compliance Recorded August 27, 1984, as Document No. 84-325375, Gibraltar Street, APN 216-290-20, 21 & 216-290-47, Carlsbad, California 92009", Project No. 12-1147Hl, Prepared by East County Soil Consultation and Engineering, Inc., Dated April 24, 2012. 2. "2010 California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of 2", Published by International Code Council. 3. "Eqfault/ Eqsearch, Version 3.0", by Blake, T.F .. 2000, Updated 2008. 4. "Limited Site Investigation, Proposed 26-Unit Apartment Complex, North Side of La Costa Avenue, West ofRomeria Street, City of Carlsbad, California"', Project No. Ol-1147Gl(I), Prepared by East County Soil Consultation and Engineering, Inc .• Dated June 9, 200 I. 5. "Geotechnical and Foundation Engineering: Design and Construction'', by Robert W. Day, 1999. 6. "1997 Uniform Building Code, Volume 2, Structural Engineering Design Provisions", Published by International Conference of Building Officials 7. "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. 8. "Geologic Maps of the Northwestern Pait of San Diego County, California", Department of Conservation, Division of Mines and Geology, by Siang S. Tan and Michael P. Kennedy, 1996. 9. '·Bearing Capacity of Soils, Technical Engineering and Design Guides as Adapted from the US Army Corps of Engineers, No. r. Published by ASCE Press, 1994. 10. "Foundations and Earth Structures. Design Manual 7.2". by Department of Navy Naval Facilities Engineering Command, May 1982, Revalidated by Change 1 September 1986. 11. '·Ground Motions and Soil Liquefaction during Earthquakes'', by H.B. Seed and J.M. Idriss, l 982. 17 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. Mr. Brian Merritt Diversified Development 7668 El Camino Real, 104-280 Carlsbad, California 92009 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 619 258-7901 FAX 619 258-7902 Subject: Pervious Concrete Pavement Recommendations Proposed I 0-Unit Residential Development (Coastal Living I 0) Lot 40 of La Costa South, Unit No. I Navarra Drive, Carlsbad, California 92009 I J ' February 28, 2014 Project No. 12-114701 References: 1. "Preliminary Grading Plan Review, Proposed 10-Unit Residential Development (Coastal Living I 0), Lot 40 of La Costa South, Unit No. I, Navarra Drive, Carlsbad, California 92009", Project No. 12-114 70 I, Prepared by East County Soil Consultation and Engineering, Inc., Dated March 19, 2013. 2. "Limited Geotechnical Investigation, Proposed I 0-Unit Residential Development (Coastal Living I 0), Lot 40 of La Costa South, Unit No. 1, Navarra Drive, Carlsbad, California 92009", Project No. 12-l 147Gl, Prepared by East County Soil Consultation and Engineering, Inc., Dated January I 0, 2013. Dear Mr. Merritt: In accordance with your request, we have reviewed the geotechnical report (Reference No. 2) to address the pervious concrete pavement for the proposed driveway at the subject site. Based on the anticipated soil conditions following site grading and the minimum requirements of the City of Carlsbad, the following pervious concrete pavement section is recommended. 6-inch pervious concrete 4-inch aggregate bedding (1/2-inch minimum size) 6-inch of open-graded gravel (2" to 3" crushed aggregate) with an underdrain and a non-woven geotextile (Mirafi 160N or equivalent) over the subgrade compacted to aminimum of 90 percent relative compaction. If we can be of further asJistance, please do not hesitate to contact our office. Respectfully submitted, MamadouSaliou Diallo, lt RCE 54071, GE 2704 MSD/md EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 (619) 258-7901 Fax 258-7902 Diversified Development, Inc. 7668 El Camino Real, 104-280 Carlsbad, California 92009 Subject: Limited Geotechnical Investigation January 10, 2013 Project No. 12-114701 Proposed 10-Unit Residential Development (Coastal Living 10) Lot 40 of La Costa South, Unit No. 1 Navarra Drive, Carlsbad, California 92009 Ladies & Gentk!men: 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 and slopewash to depths ranging from approximately 6 to 11 feet below existing grades. These soils were underlain by dense sandstone/ claystone of the Santiago Formation to the explored depth of 14 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, -- COASTAL LIVING !OID/VERS!FIED DEVELOPMENT PROJECT NO. 12-114701 TABLE OF CONTENTS INTRODUCTION .............................................................................................................................................. 3 SCOPE OF SERVICES ..................................................................................................................................... 3 SITE DESCRIPTION AND PROPOSED CONSTRUCTION ........................................................................ 3 FIELD INVESTIGATION AND LA BORA TORY TESTING ....................................................................... 4 GEOLOGY ......................................................................................................................................................... 4 Geologic Setting .................................................................................................................................... 4 Site Stratigraphy .................................................................................................................................... 4 SEJSMICITY ...................................................................................................................................................... 5 Regional Seis111icity .............................................................................................................................. 5 Seis111ic Analysis ................................................................................................................................... 5 2010 CBC Seismic Design Criteria ...................................................................................................... 6 Geologic Hazard Assessment ............................................................................................................... 6 GEOTECHNICAL EV ALU A Tl ON ................................................................................................................. 7 Compressible Soils ................................................................................................................................ 7 Expansive Soils ..................................................................................................................................... 7 Groundwater .......................................................................................................................................... 7 CONCLUSIONS AND RECOMMENDATIONS ........................................................................................... 7 GRADING AND EARTHWORK ..................................................................................................................... 8 Clearing and Grubbing .......................................................................................................................... 8 Structural Improvement of Soils ........................................................................................................... 8 Transitions Between Cut and Fill. ........................................................................................................ 9 Method and Criteria of Compaction ..................................................................................................... 9 Erosion Control ..................................................................................................................................... 9 Standard Grading Guidelines ................................................................................................................ 9 FOUNDATIONS AND SLABS ........................................................................................................................ 9 SETTLEMENT ................................................................................................................................................ 10 PRESATURATION OF SLAB SUBGRADE ................................................................................................ 10 RETAINING W,\LLS ..................................................................................................................................... 10 TEMPORARY SLOPES .................................................................................................................................. 11 TRENCH BACKFILL ..................................................................................................................................... 11 DRAINAGE ..................................................................................................................................................... 12 FOUNDATION PLAN REVIEW ................................................................................................................... 12 LIMITATIONS OF INVESTIGATION ........................................................................................................ 12 ADDITIONAL SERVICES ............................................................................................................................ 13 PLATES Plate I-Location of Exploratory Boreholes Plate 2 -Summary Sheet (Exploration Borehole Logs) Plate 3 -USCS Soil Classification Chart PAGE L-1, LABORATORY TEST RESULTS ............................................................................................. 16 REFERENCES ................................................................................................................................................. 17 2 COASTAL l!V!NG JO/ DIVERSIFIED DEVELOPlvfENT PROJECT NO. 12-1147GJ INTRODUCTION This is to present the findings and conclusions of a limited geotechnical investigation for the proposed construction of a 10-unit residential complex to be located on the south side of Navarra Drive, 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 SE:RVICES The following services were provided during this investigation: 0 Site reconnaissance and review of published geologic, seismological and geotechnical reports and maps pertinent to the project area 0 Subsurface exploration consisting of four ( 4) test pits within the limits of the proposed area of development. The test pits were logged by our Staff Geologist. 0 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. 0 Laboratory testing of samples representative of the types of soils encountered during the field investigation 0 Geologic and engineering analysis of the field and laboratory data, which provided the basis for our c:onclusions and recommendations 0 Production of this report, which summarizes the results of the above analysis and presents our findings and reconunendations for the proposed development. SITE DESCRlPTION AND PROPOSED CONSTRUCTION The subject site is located on the south side of Navarra Drive, in the City of Carlsbad, California. The vacant property encompasses an area of 21,303 square feet. The lot slopes moderately to the north. An approximately 9-foot high fill slope runs along the south side of the parcel. Vegetation consisted of grass, shrub and a few trees. Site boundaries include Navarra Drive to the north, similar residential developments to the west and east and La Costa Golf Course to the south. The preliminary site plan prepared by O'Day Consultants of Carlsbad, California indicates that the proposed construction will include a 10-unit residential complex. It is our understanding that the structures will be two and three-story, wood-framed and founded on continuous footings with slab- on-grade floors. Associated improvements will include a driveway, landscaping and other appurtenances. 3 COASTAL LIVING JOI DIVERSIFIED DEVELOPAIENT PROJECT NO. 12-1147GJ FIELD INVESTIGATION AND LABORATORY TESTING On December 7, 2012, four (4) test pits were excavated to a maximum depth of approximately 14 feet below existing grade with a Link Belt 225 trackhoe equipped with a 24-inch bucket. 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 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 sitt: 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. Tht: 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 observed in the test pits was approximately 6 inches thick and consisted of dark brown, silty sand that was dry to moist, loose and porous in consistency with some organics (roots and rootlets). Slopewash (Qsw) Slopewash was underlying the topsoil with a thickness ranging between approximately 6 and 11 feet. The material generally consisted of reddish brown, sand with silt and gravel that was dry to moist and loose to medium dense in consistency. 4 COASTAL L!VING IOI DIVERSIFIED DEVELOPMENT PROJECT NO. !2-l l47GI Santiago Formation (Tsa) Sandstone/claystone of the Santiago Formation was encountered below the slopewash. The material generally consisted of light-colored sandy clay that was moist and very stiff 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 10 kilometers (6.25 miles) 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 l 00-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 earthquakes occurring within 20 miles of a site. Based on the above, the calculated Credible RHGA at the site is 0.0.26g. 5 COASTAL LIVING JOI DJVERSIFJED DEVELOPMENT PROJECT NO. 12-l !47Gl 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 10 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 complex 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: PARAMETER VALUE 2010 CBC REFERENCE Site Class D Table 1613.5.2 Mapped Spectral Acceleration For 1.148 Figure 1613.5(3) Short Periods, S, Mapped Spectral Acceleration For a 0.432 Figure 1613.5(4) I -Second Period, S 1 Site Coefficient, F. l.041 Table 1613.5.3(1) Site Coefficient, F v 1.568 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, type and consistency of the underlying bedrock materials, 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. Tsunamis and Seiches The site is not subject to inundation by tsunamis due to its elevation and distance to the ocean. The site is also not subject to seiches (waves in confined bodies of water). 6 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-l /47GI GEOTECHNICAL 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 and Slabs recommendations section of this report. Compressible Soils Our field observations and testing indicate low compressibility within the sandstone/claystone of the Santiago Formation and part of the slopewash, which underly the site. However, loose topsoil and slopewash were encountered to a depth of approximately 3 feet below existing grades. These soils are compressible. Due to the potential for soil compression upon loading, remedial grading of these loose 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 slopewash and formational soils to determine volumetric change characteristics with change in moisture content. Expansion indexes of 3 and 77 were obtained respectively which indicate a very low to medium 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 an elevation of approximately 100 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. 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 7 COASTAL LIVING IO/ DIVERSIFIED DEVELOPAfENT PROJECT NO. I2-I I47GI 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 infom1ation 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 and slopewash cover the site to a depth of approximately 3 feet below existing grade. These subgrade soils are susceptible to settlement upon loading. Based upon the soil characteristics, we recommend the following: * * * Subgrade soils to a minimum depth of 3 feet below existing grade should be completely removed from areas, which are planned to receive compacted fills and/or structural improvements. 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 of 6 inches, moisture- conditioned within 2 percent above the optimum moisture content, and then recompacted to at least 90 percent relative compaction (ASTM DI 557 test method). Overexcavation should be completed for the structural building pads to a minimum depth of 2 feet below the bottom of the proposed footings. The limit of the required areas of overexcavation should be extended a minimum of 5 feet laterally beyond the perimeter footings. (building footprints). 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. 8 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-114701 Transitions Between Cut and Fill The proposed structures are anticipated to be founded in properly compacted fill. Cut to fill transitions below the proposed structures should be eliminated during the earthwork construction as required in the previous section. Method and Ciriteria 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 D 1557. The on-site soils, after being processed to delete the aforementioned deleterious materials, may be used for recompaction purposes. 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 infom1ation provided in the geotechnical report differs from the Standard Grading Guidelines, the requirements outlined in the report shall govern. FOUNDATIONS AND SLABS a. Continuous and spread footings are suitable for use and should extend to a minimum depth of 24 inches below the lowest adjacent grade for the proposed two and three-story structures into the properly compacted fill soils. Continuous footings should be at least 18 inches in width and reinforced with four #4 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 #4 bars spaced 12 inches 9 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-1147GJ on center (each way) and placed horizontally near the bottom. The minimum reinforcement recommended iis based on geotechnical considerations and is not intended to supercede the structural engin,~er requirements. b. Interior concrete floor slabs 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 10-mil visqueen moisture barrier. The effect of concrete shrinkage will result in cracks in virtually all-c:oncrete 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. c. Where moisture sens1t1ve floor coverings are anticipated over the slabs, the 10-mil plastic moisture barrier should be underlain by 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. d. 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. c. 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 b1;!aring 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 of the 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. RETAINING WALLS Cantilevered retaining walls should be designed for an "active" lateral earth pressure of 35 psf/ft (35 pcf EFP) for approved granular and level backfill conditions. Where the walls support 2H: 1 V 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- 10 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-l 147GI 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 psf/ft (60 pcf EPP) 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. For earthquake motions, an additional lateral earth pressure of 35 pcf (EFP) may be applied using an inverted triangular distribution if required. 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 system. At least 2 cubic feet per linear foot of free- drainage crushed rock should be provided. 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 to a maximum height of 4 feet may be constructed in fill or natural soil. Any temporary cuts beyond the above height constraints should be 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 backfilled and compacted. Utilities should be bedded and backfilled 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 soils or non-expansive imported soils, which should be placed in thin lifts, moisture-conditioned and compacted to at least 90% relative compaction. 11 COASTAL LIVING JOI DIVERSIFJED DEVELOPi\4ENT PROJECT NO. !2-//47GJ DRAINAGE Adequate measures should be undertaken to properly finish grade the site after the structures 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 structures 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 fo1111s, reinforcement or concrete for conformance with the plans and specifications. LIMITATIONS OF INVESTIGATION Our investigation was perfotmed 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 infonnation 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. 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 12 COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. /2-114701 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 pm.ts 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. 1 through 3, Page L-1 and References are parts of this report. 13 .. --:..-,,,.,...1.1& ,,__ ;, $.:""·r,,.,r \,' ... J :0 EAST COUNTY SOIL CONSULTATION & ENGINEERING, INC. 10925 HARTI.EY RD .. SUITE l. SANTEE. CA 92071 (619) 258-7901 Fax (619) 258-7902 • I I ! . I 1r_ ::a. I -" ..... , i ,it ~ I I ·-" I ': I I , " , DEPTH Surface 0.5' 2.0' 3.0' 4.5' 5.0' 7.0' 7.5' 9.0' DEPTH Surface 0.5' 3.0' 6.0' 8.0' 9.0' COASTAL LIVING JOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-l 147GJ PLATEN0.2 SUMMARY SHEET TEST PIT NO. I SOIL DESCRIPTION TOPSOIL dark brown, dry to moist, loose. porous, silty sand with rootlets SLOPEWASH (Qsw) reddish brown, dry to moist, loose to medium dense, sand with silt " becomes moist and medium dense ,. abundant gravels SANTIAGO FORMATION (Tsa) light gray, moist to wet, medium dense to dense, sandstone/ claystone '" " "' bottom of test pit, no caving, no groundwater test pit backfilled and compacted with sheepsfoot roller 12/7/ 12 TEST PIT NO. 2 SOIL DESCRIPTION TOPSOIL dark brown, dry to moist, loose, porous, silty sand with rootlets SLOPEWASH (Qsw) reddish brown, dry, loose, sand with silt and gravel becomes moist and medium dense SANTIAGO FORMATION (Tsa) light gray, moist to wet, medium dense to dense, sandstone/ claystone ., ~-"' bottom oftest pit, caving in upper 3 feet, no groundwater test pit backfilled and compacted with sheepsfoot roller 12/7/12 y 119.7 131.3 105.9 y 105.3 Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN% 14 M 5.6 8.5 15.4 M 17.9 DEPTH Surface 0.5' 4.0' 9.0' 11.0' DEPTH Surface 0.5' 3.0' 11.0' 14.0' COASTAL LIVING 10/ DIVERSIFIED DEVELOPMENT PROJECT NO. 12-1147GJ PLATE NO. 2 (Continued) SUMMARY SHEET TEST PIT NO. 3 SOIL DESCRIPTION TOPSOIL dark brown, dry to moist, loose, porous, silty sand with rootlets SLOPEW ASH (Qsw) y reddish brown, dry to moist, loose to medium dense, sand with silt and gravel becomes moist to wet and medium dense SANTIAGO FORMATION (Tsa) light reddish gray, moist, medium dense to dense, sandstone/ claystone bottom of test pit, no caving, no groundwater test pit backfilled and compacted with sheepsfoot roller 12/7/12 TEST PIT NO. 4 SOIL DESCRIPTION TOPSOIL dark brown, dry to moist, loose, porous, silty sand with rootlets SLOPEW ASH (Qsw) y reddish brown, dry to moist, loose to medium dense, sand with silt with gravel becomes moist to wet and medium dense SANTIAGO FORMATION (Tsa) light reddish gray, moist, medium dense to dense, sandstone/ claystone bottom of test pit, no caving, no groundwater test pit backfilled and compacted with sheepsfoot roller 1217112 Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN % 15 M M MAJOR DIVISIONS SYMBOL DESCRIPTION G\V WELL GRADED GRAVELS OR GRAVEL· SAND MIXTURES, LITTLE OR NO FINES GRJ\VELS GP (MORE THAN \I, POORLY GRADED GRAVELS OR GRAVEL-SAND OF COARSE MIXTURES. LITTLE OR NO FINES FRACTION GM SIL TY GRAVELS, GRA YEL-SAND-SIL T MIXTURES >NO. 4SIEVE SIZE) COARSE GC I GRAINED SOILS CLAYEY GRAVELS, GRAVEL-SAND-CLAY MIXTURES (MORE THAL"l 1/1 OF SOIL > SW I NO. 200 SIEVE SIZE) WELL GRADED SANDS OR GRA YELL Y SANOS, UTILE OR NO FINES SANDS SP I (MORE THAN Y: POORLY GRADED SA.'IDS OR GRAVELLY SANDS, OF COARSE UTILE OR NO FINES FRACTION SM I < NO. 4 SIEVE SIL TY SANDS, SILT-SAND MIXTURES SIZE) SC CLAYEY SA.'IDS, SAND-CL.-\ Y MIXTURES ML I INORGANIC SIL TS AND VERY HNE SA.\JDS, ROCK SILTS & FLOCR, SIL TY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PL-\STICITY CLAYS CL I INORGANIC CLAYS OF LOW TO MEDIUM LIQl:ID LIMIT PL-\STICITY, GRA YELL Y CL-\ YS, SANDY CLAYS, < 50 SIL TY CL-\ YS. LEAN CLAYS FINEGRUNED OL I SOI:LS ORGA.'ilC SILTS A.'iD ORGANIC SILTY CU. YS OF LOW PLASTICITY (MORE TH..\.'I Y, OF SOIL< MH I NO. 200 SIEVE SIZE) INORGANIC SILTS, MICACEOUS OR DlATOMACEOliS SILTS & FINE SANDY OR SIL TY SOILS. ELASTIC SILTS CLAYS CH I INORGANIC CLAYS OF HIGH PLASTICITY, FAT LIQUID LIMIT > 50 CL\YS OH I ORGANIC CL-\ YS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SIL TY CL-\ YS. ORGANIC SIL TS HIGHLY ORGA.'HC SOILS I Pt I PSAT AND OT'r!ER HIGHLY ORGA.'11C SOILS CLASSIFICATION CHART (C'NIFIED SOIL CLASSIFICATION SYSTE:VI) CL.-\SSIFIC\. TION RA.'iGE OF GR-\!;,; SIZES LS. ST.-\.'iDARD SIEVE SIZE BOCLDE:Rs Above 12 !nc:ies COBBLES I 1: !nc:i<:s To J !nc:ies GR-\VEL J Inches to No. 4 C uars~ 3 [nc s o n h he t ~, .. ~ c. Fine ~1, !nc:i to ~o. -I SA.'iD No. -I to '.'lo. 200 Cuarsc No. 4 to No. 10 Medium No. 10 to No. -10 Fine No. -10 to No. 200 SILT A:'ID CL.-\ Y I Be!ow No. :!00 GRAIN SIZE CHART I I I GR-\IN SIZE !;'I; :',11LLI:\!ETERS Above 305 305 Tu 76.: 76.2 to 4. 76 6 19lca-176 7 -~~o ~9.1 4.76:oJ.r.; 4. 76 :o DO 2."JO to 0 . .1:0 0.420 :o ').')7 .! B.:!ow O.J7.! E.-\ST COUNTY SOIL CONSt:LTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUTE "l'" SANTEE, CALIFO~'IIA 920":'l CS.C.S. SOIL CLASSIFICATIO~ I I .. I I ! X ~ "1 ,. ~ :a ~ :~r-..,.--;,l'~.,--~.,,...,~~~~~~--1 I ~"~tH !Or-::z=:;::::==::7'"-;---ji--;----;-~;---;----j IQ :o !a 40 ~O 50 70 !O iO !CO PLASTICITY CHART COASTAL LIVING 10 PROJECT PROJECT NO. 12-i147G1 P:.ATE ~O. 3 JAN. 10, 2013 ' ' COASTAL LIVING JOI DIVERSIFIED DEVELOPA1ENT PROJECT NO. 12-! 147GI INITIAL MOISTURE CONTENT(%) 9.3 14.5 U.S. Standard Sieve Size 2" I" 1 /2" 3/8" #4 #8 #16 #30 #50 #100 #200 uses PAGE L-1 LABO RA TORY TEST RESULTS EXP ANSI ON INDEX TEST (ASTM D4829) INITIAL DRY SATURATED MOISTURE CONTENT(%) DENSITY EXPANSION 17.1 29.3 (PCF) INDEX 111.3 3 98.9 77 PARTICLE SIZE ANALYSIS (ASTM D422) Percent Passing Percent Passing TP-3@6.0' TP-4@6.0' Slopewash Slopewash - -100 -83 100 77 99 63 95 40 81 17 48 8 16 5 8 4 6 3 SP-SM SW 16 LOCATION TP-2@ 3.0' TP-2@8.0' Percent Passing TP-2@8.0' Santiago Formation - - -- 100 99 98 96 93 87 79 CL COASTAL LIVING IOI DIVERSIFIED DEVELOPMENT PROJECT NO. 12-l /47Gl REFERENCES I. "Limited Geotechnical Investigation, Vista La Costa Residential Development, Parcel 2 of Certificate of Compliance Recorded August 27, 1984, as Document No. 84-325375, Gibraltar Street, APN 216-290-20, 21 & 216-290-47, Carlsbad, California 92009", Project No. 12-l 147HI, Prepared by East County Soil Consultation and Engineering, Inc., Dated April 24, 2012. 2. "2010 California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of 2", Published by International Code Council. 3. "'Eqfault/ Eqsearch, Version 3.0", by Blake, T.F., 2000, Updated 2008. 4. "Limited Site Investigation, Proposed 26-Unit Apartment Complex, North Side of La Costa Avenue, West of Romeria Street, City of Carlsbad, California"', Project No. 0 l-l l 47G I (I), Prepared by East County Soil Consultation and Engineering, Inc., Dated June 9, 200 I. 5. ''Geotechnical and Foundation Engineering: Design and Construction", by Robert W. Day, I 999. 6. ·'1997 Uniform Building Code. Volume 2, Structural Engineering Design Provisions", Published by International Conference of Building Officials 7. "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. 8. "Geologic Maps of the Northwestern Patt of San Diego County, California", Department of Conservation, Division of Mines and Geology, by Siang S. Tan and Michael P. Kennedy, 1996. 9. ''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. Io. "Foundations and Earth Structures. Design Manual 7.2". by Depa1tment of Navy Naval Facilities Engineering Command, May 1982, Revalidated by Change I September 1986. 11. '·Ground Motions and Soil Liquefaction during Earthquakes'', by H.B. Seed and J.M. Idriss, 1982. 17