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Home My WebLink AboutCDP 2017-0021; OCEAN STREET RESIDENCE; LIMITED GEOTECHNICAL INVESTIGATION; 2017-03-02Mr. Alan Shafran 1673 Amante Court Carlsbad, California 92011 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 (619) 258-7901 Fax 258-7902 Subject: Limited Geotechnical Investigation Proposed Single-Family Residence 2680 Ocean Street City of Carlsbad, California 92008 Dear Mr. Shafran: March 2, 2017 Project No. 17-110605 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 residential development. Our investigation has foWld that the proposed building pad is underlain by an approximately 6 to 12-inch layer of topsoil over moderately dense to dense terrace deposits to the explored depth of 7 feet. It is our opinion that the construction of the proposed residence is geotechnically feasible provided the recommemdations 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. Mamadou Saliou Diallo, P .E. RCE 54071, GE 2704 MSD/md ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5 TABLE OF CONTENTS INTRODUCTION .............................................................................................................................................. 3 SCOPE OF SERVICES ...................................................................................................................................... 3 SITE DESCRIPTION AND PROPOSED CONSTRUCTION ...................................................................... !.3 FIELD INVESTIGATION AND LABORATORY TESTING ........................................................................ 4 GEOLOGY ......................................................................................................................................................... 4 Geologic Setting .................................................................................................................................... 4 Site Stratigraphy .................................................................................................................................... 4 SEISMICITY ...................................................................................................................................................... 5 Regional Seismi~ity ............................................................................................................................. ;.s Seismic Analysis ................................................................................................................................... S 2016 CBC Seismic Design Criteria .................................................................................................... ,.6 Geologic Hazard Assessment. ............................................................................................................... 6 GEOTECHNICAL EVALUATION .................................................................................................................. 7 Compressible Soils ................................................................................................................................ 7 Expansive Soils .................................................................................................................................... ,. 7 Groundwater ........................................................................................................................................ 1• 7 CONCLUSIONS AND RECOMMENDATIONS ............................................................................................ 8 GRADING AND EARTJIWORK ...................................................................................................................... 8 Clearing and Grubbing .......................................................................................................................... 8 Structural hnprovement 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 ................................................................................................................................................. 110 PRESATURATION OF SLAB SUBGRADE ................................................................................................. 110 TEMPORARY SLOPES .................................................................................................................................. ,10 TRENCH BACKFILL ...................................................................................................................................... 111 DRAINAGE ...................................................................................................................................................... lll FOUNDATION PLAN REVIEW .................................................................................................................... 11 LIMITATIONS OF IN'VESTIGATION ......................................................................................................... 1 11 ADDITIONAL SERVICES ............................................................................................................................ 12 PLATES Plate 1-Location of Exploratory Boreholes Plate 2 -Summary Sheet (Exploratory Borehole Logs...................................................................... 3 Plate 3 -USCS Soil Classification Chart PAGE L-1, LABORATORY TEST RESULTS ............................................................................................. 14 REFERENCES ................................................................................................................................................ 15 2 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5 INTRODUCTION This is to present the findings and conclusions of a limited geotechnical investigation for the proposed single-family residence to be located at 2680 Ocean 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: 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) boreholes within the limits of the proposed area of development. The boreholes were logged by our Staff Geologist. 0 CoJlection of representative soil samples at selected depths. The obtained samples were s.ealed in moisture-resistant containers and transported to the laboratory for subsequent analysis. 0 Laboratory testing of samples representative of the types of soils encoW1tered 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 recommendations for the proposed development SITE DESCRIPTION AND PROPOSED CONSTRUCTION The subject site is an rectangular-shaped residential lot located on the east side of Ocean Str~t, in the City of Carlsbad, California. The property which encompasses an area of approximately 3,500 square feet (70' X 50') is occupied by a one-story, single-family residence with a detached gr age. The site is gently sloping to the west. Vegetation consisted of grass, shrub and a few trees. The parcel is bordered by Ocean Street to the west and similar residential developments t? the remaining directions. The site plan prepared by Wright Design of Carlsbad, California indicates that the proi osed construction will consist of a single-family residence including an accessory dwelling! unit following demolition of the existing structures. The new structure will be two-story, wood-frr ed and founded on continuous footings with a slab-on-grade floor. I 3 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5 FIELD INVESTIGATION AND LABORATORY TESTING On February 16, 2017, four (4) boreholes were excavated to a maximum depth ofapproximat~ly 7 feet below existing grade with a hand auger. The approximate locations of the boreholes are sqown on the attached Plate No. I, entitled "Location of Exploratory Boreholes". 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, 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 site is located within the southern portion of what is known as the Peninsular Range Geomorphic Province of California. The geologic map pertaining to the area (Reference Nb. 5) indicates that the site is underlain by Pleistocene terrace deposits (Qt). Site Stratigraphy The subsurface descriptions provided are interpreted from conditions exposed dwing 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 provid~d 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 boreholes was approximately 6 o 12 inches thick and consisted of dark brown, silty sand that was dry, loose and porous in consistenc with some organics (rootlets). Terrace Deposits (Qt) Terrace deposits were underlying the topsoil. They generally consisted of reddish brown, silty sand that was moist and medium dense to dense in consistency. 4 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5 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 paj-allel 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 I evaluating the effect an earthquake has on a site are the magnitude of the event, the distance lfrom 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 and 1.6 million years old. Seismic Analysis Based on our evaluation, the closest known "active" fault is the Rose Canyon Fault located approximately 7 kilometers (4.4 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 the 2008 National Hazard Maps from the SGS website and Seed and Idriss methods for active Quaternary faults within a 50-mile radius of the subject site. The site may be subjected to a Maximum Probable Earthquake of 6.9 Magn!itude along the Rose Canyon Fault, with a corresponding Peak Ground Acceleration of 0.45g. The maximum Probable Earthquake is defined as the maximum earthquake that is considered lik~ly to occur within a I 00-year time period. The effective ground acceleration at the site is associated with the part of significant g11°und 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 ~ the Repeatable High Ground Acceleration (RHGA). It has been determined by Ploessel and SlQ>sson (1974) that the RHGA is approximately equal to 65 percent of the Peak Ground Acceleratid~ for earthquakes occurring within 20 miles of a site. Based on the above, the calculated Credible RHGA at the site is 0.29g. I 2016 CBC Seismic Design Criteria I A review of the active fault maps pertaining to the site indicates the location of the Rose Canyon Fault Zone approximately 7 km to the west. Ground shaking from this fault or one of the ~ajor 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 single-family resi~ence should be designed in accordance with seismic design requirements of the 2016 California Bu~lding 5 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO.17-1106D5 Code or the Structural Engineers Association of California using the following seismic d~sign parameters: PARAMETER '( l • ,! Site Class Mapped Spectral Acceleration For Short Periods, Ss Mapped Spectral Acceleration For a ]-Second Period, S1 Site Coefficient, Fa Site Coefficient, Fv Adjusted Max. Considered Earthquake Spectral Response Acceleration for Short Periods, SMs Adjusted Max. Considered Earthquake Spectral Response Acceleration for I-Second Period, SM1 5 Percent Damped Design Spectral Response Acceleration for Short Periods, Sos 5 Percent Damped Design Spectral Acceleration for I-Second Period, S01 Geologic Hazard Assessment Ground Rupture Response VALUE 2016 CBC & ASCE 7 REFERENCES D Table 20.3-1/ ASCE 7, Chanter 20 I 1.174g Figure 1613.3.1(1) 0.45 lg Figure 1613.3.1(2) 1.030 Table 1613.3.30) 1.549 Table 1613.3.3(2) l.210g Equation 16-37 0.698g Equation 16-38 0.807g Equation 16-39 0.466g Equation 16-40 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 o]jl.-site utility lines and connections. Li quefaction Liquefaction involves the substantial loss of shear strength in saturated soils, usually sandy soils {ith a loose consistency when subjected to earthquake shaking. Based on the absence of sh~llow groundwater and consistency of the underlying bedrock materials, it is our opinion that the pot¢ntial 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 developmr1 t or adjacent properties. Tsunamis and Seiches The site is not subject to inundation by tsunamis due to its elevation. The site is also not subj1rct to seiches (waves in confined bodies of water). 6 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1 J06D5 GEOTECHNICAL EVALUATION Based on our investigation and evaluation of the collected information, we conclude that the pro~osed residential development is feasible from a geotechnical standpoint provided the recommend~tions herein will be properly implemented during construction. In order to provide a uniform support for the proposed structure, footings should be excavateq into properly compacted fill soils or extended to the dense terrace deposits. The new foundation may consist of reinforced continuous footings with reinforced slabs. Recommendations and criteria for foundation design are provided in the Foundation and Slab recommendations section of this repo:tit Compressible Soils Our field observations and testing indicate low compressibility within the dense terrace deposits, which underlie the site. However, loose topsoil and moderately dense terrace deposits :were encountered to a depth of approximately 3 feet below surface grades. These soils are compressible and should be overexcavated and recompacted unless footings are extended to the dense terrace deposits. Following implementation of the 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 Earth~ork Recommendations section of this report. Expansive Soils An expansion index test was performed on a representative sample of the terrace deposits to determine volumetric change characteristics with change in moisture content. An expansion irdex of O was obtained which indicates a very low expansion potential for the foundation soils. Groundwater Static groundwater was not encountered to the depths of the boreholes. The building pad is loeated at an elevation over 40 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. I 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 s~te is suitable for the proposed residential development provided the recommendations set fortij are implemented during construction. 7 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-l 106D5 GRADING AND EARTHWORK Based upon the proposed site plan and the information obtained during the field investigatiom, we anticipate that the proposed structure will be founded on continuous footings, which are supported by properly compacted fill or dense terrace deposits. 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 Grubbiqg The area to be graded or to receive fill and/or structure should be cleared of vegetation and waste from the demolition of the existing structures. 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 bole , 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 fiiom our field and laboratory analysis indicates that loose topsoil and modetateJy dense terrace deposits cover the building pad to a depth of approximately 3 feet below existing grade. These surficial soils are susceptible to settlement upon loading. Based upon the soil characteristics we recommend the following: * * * * All topsoil and other loose natural soils should be 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 D1557 test method). I Overexcavation should be completed for the structural building pad to a minimum d;Eth of 2 feet below the bottom of the proposed footings. The limit of the required ea of overexcavation should be extended a minimum of 5 feet laterally beyond the peri eter footing (building footprint). Soils utilized as fill should be moisrure-conditioned and recompacted in conformance wijh the following Method and Criteria of Compaction section of this report. The actual depth and extent of any overexcavation and recompaction should be evaluated in the field by a representative ofECSC&E. An alternative to the overexcavation and recompaction of subgrade is to extend footings for the proposed structure to the dense terrace deposits. However, for slab suppott, we recommend ov.erexcavation and recompaction of the upper 2 feet of sub grade. 1 8 ALAN SHAFRAN! 2680 OCEAN STREET PROJECT NO. 17-1106D5 Transitions Between Cut and Fill The proposed structure is anticipated to be founded in either properly compacted fill or dense terrace deposits. Cut to fill transitions below the proposed structure should be completely 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 1other deleterious materials. Fill soils should be compacted by suitable compaction equipment in unifonn 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 DI 557. On-site soils, after being processed to delete the aforementioned deleterious materials, may be u yd 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 ~n to ensure that these soils arr-e not detrimentally expansive. Erosion Control Due to the granular characteristics of on-site soils, areas of recent grading or exposed ground may be subject to erosion. During construction, surface water should be controlled via benns, gtavel/ sandbags, silt fences, straw wattles, siltation and bioretention basins, positive surface grades or bther 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 stonn drains and minimize pollution. The contrlactor should take measures to prevent erosion of graded areas until such time as permanent drainagr, and erosion control measU11es have been installed. After completion of grading, all excavated surjfaces should exhibit positive drainage and eliminate areas where water might pond. Standard Grading G!!idelines 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 California Building Code, and the requirements of the jurisdictional agency. Where the information provided in the geotechnical report differs ltrom 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 bf 18 inches for the proposed two-story structure into the properly compacted fill soils or dense te~ace deposits. Continuous footings should be at least 15 inches i~ width and reinforced with a miniFlurn of four #4 steel bars; two bars placed near the top of the footmgs and the other two bars place~ near the bottom of the footings. Isolated or spread footings should have a minimum width of 24 inphes. Their reinforcement should consist of a minimum of #4 bars spaced 12 inches on center ( each lway) 9 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO.17-1106D5 and placed horizontally near the bottom. These recommendations are based on geotechnical considerations and are not intended to supersede the structural engineer requirements. b. Interior concrete slabs should be a minimum 5 inches thick. Reinforcement should consist of #3 bars placed at 18 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 I 0-mil vis~ueen 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 l 0-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 1 2 inches into properly compacted fijll soils or the dense terrace deposits as set forth in the 2013 California Building Code, Table 1806.2. 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. e. 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 typd and minor thickness of the fill soils anticipated under the proposed footings and the light building lr1 ads, total and differential settlement should be within acceptable limits. I PRESATURATION OF SLAB SUBGRADE Due to the granular characteristics of the subgrade soils, presoaking of subgrade prior to co~crete 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 preparation and foundation excavation. TEMPORARY SLOPES I For the excavation of foundations and utility trenches, temporary vertical cuts to a maximum hei~t 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 I: 1 (horizontal to vertical) slope atio. OSHA guidelines for trench excavation safety should be implemented during construction. 10 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO.1 7-1106D5 TRENCH BACKFILL Excavations for utility lines, which extend under structural areas should be properly backfilJed and compacted. Utilities should be bedded and backfilled with clean sand or approved granular oil 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. DRAINAGE Adequate measures should be undertaken 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 2 percent is recommended in hardscape areas adjacent to the structure. In earth areas, a minimum gradient of 5 percent away from the structure for a distance of at least 10 feet should be provided. If this requirement cannot be met due to site limitations, drainage can be done through a swaile in accordance with Section 1804.4 of the 2016 California Building Code. 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 se~king 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 plan and detailss during the design phase to ~ssure 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 concretb for conformance with the plans and specifications. 1 LIMIT A TIO NS OF INVESTIGATION Our investigation was }1)erformed using the skill and degree of care ordinarily exercised, under similar circumstances, by reputable soils engineers and geologists practicing in this or similar localitid . 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 Jther without the written consent of the client and ECSC&E, Inc. I The samples collected and used for testing, and the observations made, are believed representative of site conditions; howe'(er, soil and geologic conditions can vary significantly between exploration trenches, boreholes and surface exposures. As in most major projects, conditions revealfd by construction excavations may vary with preliminary findings. If this occurs, the changed con1tions must be evaluated by a representative of ECSC&E and designs adjusted as required or altrrnate designs recommended. 11 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-l 106D5 Tbis 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 wo*s of man on this or adjacent properties. 1n addition, changes in applicable or appropriate tandard 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 subjr ct to review and should be uwdated after a period of two years. ADDITIONAL SERVilCES The review of plans and specifications, field observations and testing under our direction are integral parts of the recommenclations 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 pot~ntial claims that may arise during construction. Observation and testing are additional services, which are provided by our firm, am.d should be budgeted within the cost of development. Plates No. 1 through 3, Page L-1 and References are parts of this report. 12 . f • .........__. I_ -. ----,-.,I•·- ......... , •• ..,.. J.,_..,,, -r~ a-,,.....J.,.J . I -~--I _..., __ ...... -.. ·1•1 ' --1 l ~~~~~~:.-I I ·--'J!"";'.' •' -I ::~·::.:;~.~~ ··---! ! ..... ' -~· ~ .... =-; ----,.. l t__--_-: __ I -----· _o ·,-• I I 1 -1 I ...,...;;;;:;-_..-~ I ' ... ... . • . ------·-----. . -----·· l --. ;) EAST COUNTY SOIL CONSULTATION & ENGINEERING, INC. 10925 HARn.EY RD .. surtE I. SANTEE. CA.92071 _(619) 258-?~I Fu (619) 258-7902 I ,l-/$Jl-:4IFRMI / ?6(1:) oeow 1imar I DEPTH Surface 1.0' 3.0' 6.0' ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO.17-1106D5 PLATE NO. 2 SUMMARY SHEET BOREHOLE NO. 1 SOIL DESCRIPTION TOPSOIL dark brown, moist, loose, porous, silty sand with rootlets TERRACE DEPOSITS (Qt) reddish b1:own, moist, medium dense, silty sand becomes clense bottom of borehole, no caving, no groundwater borehole backfilled 2/16/17 y M ----------.. ---·----------·-·------------·------·------ DEPTH Surface 1.0' 3.0' 4.0' BOREHOLE NO. 2 SOIL DESCRIPTION TOPSOIL dark brown, moist, loose, porous, silty sand with rootlets TERRA~E DEPOSITS (Qt) reddish birown, moist, medium dense, silty sand becomes dense bottom of borehole, no caving, no groundwater borehole backfilled 2/16/17 y 114.7 ---------·-----------------------------------·---------------------------------- DEPTH Surface 0.5' 2.0' 3.0' 4.0' BOREHOLE NO. 3 SOIL DESCRIPTION TOPSOIL dark brown, moist, loose, porous, silty sand with rootlets TERRACE DEPOSITS (Qt) reddish bliown, moist, medium dense, silty sand " u " u " becomes dense bottom of borehole, no caving, no groundwater borehole backfilled 2/16/17 y 101.8 ---------------------·-------· .. -----···------- DEPTH Surface 1.0' 3.0' 7.0' BOREHOLE NO. 4 SOIL DESCRIPTION TOPSOIL dark brown, moist, loose, porous, silty sand with rootlets TERRACE DEPOSITS (Qt) reddish brown, moist, medium dense, silty sand becomes, dense bottom of borehole, no caving, no groundwater borehole backfilled 2/16/17 y -------------------------------------------------------------------------------------- Y = DRY DENSITY IN PCF M = MOISTURE CONTENT IN% 13 M 10.7 M 11 .3 M SOIL cu.ssi'FICATION CHART MAJOR DIVISIONS COARSE GRAINED SOILS MORE.'THANS1!% OF MATERIAL. IS LARGER nwl NO. 2001SIMSIZE FINE GRAINED SOILS MO!UaTHANIIO% OF MATERIAi. IS l~THANNO, 200 SIEVE IIZE GRAVEL ANO GRAVELLY SOILS MORETHAN50% OF COARSE FAAC'l'ION RE1'AJNEl) ON NO. 4 SIEVE SAND ANO SANDY SOILS MORETiw.110% OFCOAASE FAACTIONPASSING ON NO. U IEV! SILTS AND CLAYS SILTS ANO CLAYS CLEAN GRAVELS (I.ITTL.£ OR NO l'lNES) GRAVELS WITH FINES CLEAN SANDS SANDS WITH FINES (APPRiCIAILE AMOUNT OF '1NES) UCUIOUMIT LESSTHAN50 LIQLJIOLIMIT GREATER THAN 50 HIGML Y ORGANIC SOILS NOTE: OUAL SYl.ll!OUi Alli USEO TO INDICATE BORDERLINE SOIL CLASSIFICA1'10NS Cl..ASSIFICA TlON RANCE OF GRAIN SIZ.£S U.S. STA!'t'DARD GRAIN S11.E IN SIEVESJ.ZE MILLIMETERS BOULDERS Above 12 lnchc, Above 305 COBBLES 12 Inches To 3 lni:hcs lOS To 76.2 GRAVEL 3 1ncm:s to No. 4 76.2 to 4.76 Coarse 3 Inches to ¼ Inch 76.2 to 19.1 Fine: ¼ Inch w No. 4 19.1 t006 SAND No. 4 to No. 200 06I00.07~ Coanc No.4toNo.10 4.76 to 2.00 Medium No. 10 to No. 40 2.00 to 0.420 Fine No. 40 10 No. 200 0.420 to 0.074 SILT AND CLAY Below No. 200 Below 0.074 GRAIN SIZE CHART EAST COUNTY son.. CONSULTATION & ENGINEERING, INC. l 0925 HARn.BY RD~ surrs I, SANTEE. CA .92071 (619) 258-7901 Pu (619) 258-7902 LETTER GW GP GM SW SP SM SC ML CL CL MH CH OH PT TYPICAL DESCRIPTIONS WELL-GRADED GRAVELS, GRAVEL· SANO MIXTLJRES, LITil.E OR NO FINES POOR:. Y-GRADEC GRAVEi.$, GRAVEL• SANO MIXT1JRES, UTTLE OR NO FINes SILlY GAA\IELS, GRAVEL. SI.NO -SILT 11,llXT\JRES Wl:U.-SANOS, GAAi/ELL Y SANOS, UTTLI! OR NO l'lNES POORL Y-GAAOEO SMIO.S. GRA\/El.l Y SANO. LlmE OR NO FINES SIL lY SI.NOS. 51\NO • SILT MIXTIJRES INORGAHJC SIL TS ANO VERY l'INI SANOS, ROCK Fl.OUR, Ill TY OR CLAYEY FIN£ SANOS OR CLAVEY SIL TS Wlfl,( SLIGHT PI..ASTlCITY INORGANIC c.AYS OF LOW T0 MEDIUM PLASTlCITY, CillAI/Ell Y CV.YI, SANDY CIAYS, SIL TY CI.AYS, LEAN CLAYS ORGANIC SIL TS ANO ORGANIC SIL TY C!AYS OF LOW PI.Ml'ICl'TY INO~IC SIL TS, MICACEOUI OR CIA TOMACEOUli FINE SANO OR 8U. TY SOILS INORGANIC CLAYS OF HICiH PI.MT!CITY ORGANIC CLAYS OF MEOIUM TO HIGH PLASTICITY, ORGANIC 61LT6 PEAT, HUMUS, SWAMP SOILS W!Tl1 HIGH ORGANIC CONTENTS 10 l · I I / V I/ Ck ~7 / /" I/ CL V i \0 / I ,,, /' i ' ....... I -W\AOL I I I -·-' I ~Vi I ' I I I I C 1C 10 10 .a SO ID 70 IO tO I ICO UCUIO UWIT (U.). ,; PLASTICITY CHART ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5 PAGEL-1 LADORA TORY TEST RESULTS EXP ANSI ON INDEX TEST (ASTM D4829) INITIAL DRY INITIAL MOISTURE CONTE T(¾) SATURATED MOISTURE CONTENT{%) DENSITY EXP ANS ION (PCF) INDEX LOCATION 9.3 16.9 111 .3 0 BH-1 @2.0' PARTICLE SIZE ANALYSIS (ASTM D422) I U.S. Standard Percent Passing Pe~t Passing Sieve Size BH-1 @2.0' BH-1 @4.0' Terrace Deoosits Terrace Deposits 1" -- 1/2" -- 3/8" -- #4 -- #8 -- #16 100 100 #30 90 90 #50 42 41 #100 22 19 #200 16 15 I uses SM SM I 14 ALAN SHAFRAN/ 2680 OCEAN STREET PROJECT NO. 17-1106D5 REFERENCES 1. "2016 California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of 2", Published by International Code Council. 2. "Geologic Map of the San Diego 30' x 60' Quadrangle, California", by Michael P. Kennedy and Siang S. Tan, 2008. 3. "Geotechnical and Foundation Engineering: Design and Construction", by Robert W. Day, 1999. 4. "Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada to be used with 1997 Uniform Building Code", Published by International Conference of Building • I Officials. 5. "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. 6. "Bearing Capacity of Soils, Technical Engineering and Design Guides as Adapted from the US Anny Corps of Engineers, No. 7", Published by ASCE Press, 1994. 7. "Foundations and Earth Structures, Design Manual 7.2", by Department of Navy Naval Facilitie Engineering Co111mand, May 1982, Revalidated by Change 1 September 1986. 8. "Ground Motions and Soil Liquefaction during Earthquakes", by H.B. Seed and 1.M. Idriss, 1982. 15