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Home My WebLink AboutPD 05-14; JOHNSON RESIDENCE; REPORT OF PRELIMINARY GEOTECHNICAL RESIDENCE; 2005-09-21~larch 9, 2006 Terry Johnson Post Office Box 131-1---1-6 Carlsbad, California 92013 w Cl lRISTIAN WHEELER lNCINL[RINC, • C\VE 2050527.05 SUBJECT: GRADING PLAN REVIEW, PROPOSED SINGLE-FAMILY RESIDENCE, LOT 71 7335 EL FUERTE STREET, CARLSBAD, CALIFORNIA. References: 1) Report of Preliminary Geo technical Investigation, Proposed Single-Family Residence, Lot 71, El Fuerte Street, Carlsbad, California, by Christian \Vheeler Engineering, Report No. 2050527.03, dated September 21, 2005. · 2) Grading Plan for: Johnson Residence, 7335 El Fuerte Street, Carlsbad, California, by LDE Consulting, Project No. PD 05-14, Drawing No. 436-3A, undated. Dear Mr. Johnson: In accordance \Vi.th the request of l\fr. Jaafar Sleiman and per our recommendations, we have reviewed the referenced grading plan in order to ascertain that the recommendations presented in the referenced report have been implemented, and that no additional recommendations are needed due to changes in the proposed construction. Based on this review, it is our opinion that our geotechnical recommepdations have been . properly incorporated into the project grading plan and that no additional recommendations are necessary at this time. If you have any questions after reviewing this report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, a ~ENGINEERING Charles H. Christian, RGE #00215 (.II( ::sec cc: (2) Submittc-d (! i J,l)I-: <:,msulring, 21,n S. 1-:l ( :.1mino Real. Suite 1<14, Oceanside,(;..\ 92054; (I) ,·ia email 1skiman@IJ-enginccnng.com 4925 Mercury Street + San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 ,~Yb OS/{ 4~~ r1 f l I . w CHRISTIAN WHEELER ENGINEER.ING - REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 71 CARLSBAD, CALIFORNIA PREPARED FOR: TERRY JOHNSON POST OFFICE BOX 131446 CARLSBAD, CALIFORNIA 92013 PREPARED BY: CHRISTIAN WHEELER ENGINEERING 4925 MERCURY STREET SAN DIEGO, CALIFORNIA 92111 4925 Mercury Street + San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 Ii r ; I , I , I L f : September 21, 2005 Terry Johnson Post Office Box 131446 Carlsbad, California 92013 -w CHR.ISTIAN WHEELER. l,:NGINEERING - CWE 2050527.03 SUBJECT: REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATIO_N, PROPOSED SINGLE-FAMILY RESIDENCE, LOT 71, EL FUERTE STREET, CARLSBAD, CALIFORNIA. Dear Mr. Johnson: In accordance with your request, we have completed a preliminary geotechnical investigation for the single- family residence proposed at the subject property. \X1e are presenting herein our findings and recommendations. In general, we found the subject property suitable for ·the proposed development, provided the recommendations presented herein are followed. Based on our investigation, we have concluded the l ,· following: I : · • J u I i L L L • The site is ukimately underlain by dense to very dense metavolcanic rock and associated sedimentary rock, but is mantled by ; two-to three-foot-thick layer of relatively loose surficial soils thl!t are considered unsuitable in their present condition to support fill and/or settlement-sensitive improvements. As such, any surficial soil that is not removed by the planned grading will need to be overexcaYated in the areas to support fill and/ or settlement-sensitive improvements and be repl~ced as properly compacted fill. • The existing residual soil was determined to be very highly expansive. As such, tl1is material will need to be mixed with the sandy portions of the on-site soil to create a nondetri.tnentally expansive mix prior to placeme11t as structural fill,~; ~e placed.only in landscape areas where no concrete flatwork is planned. 4925 Mercury Street+ San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 C\'\'E 2050527.03 -September 21, 2005 -Page No. 2 • Based on the proposed grading plan, the residence will supported by fills of varying thickness . .Additionally, we anticipat~ that although the metavolcanic rock and associated sedimentary rock material can be excavated to the·proposed depths using heavy grading equipment, it will be difficult to excavate for foundations and/or utilities in th.is material using lightweight trenching equipment. Based on .these conditions, it will be necessary to undercut the cut portions of the proposed pads during grading to mitigate the potential for differential settlement and so that it will be possible to use nonnal trenching equipment during the construction of the home. • TI1e site is located in an area that is relatively free of geologic hazards that will have a significant effect on the proposed development. The most likely geologic hazard that could affect the site is ground shaking due to seismic activity along one of the ~egional actiYe faults. HoweYer, c~>nstruction in accordance with the requirements of the Uniform Building Code and other governmental regulations should prm·ide a leY~l of life-safety suitable for the type of de,relopment proposed. If you have any quescions after reviewing this report, please do not hesitate to contact our office. This opportunity !o be of professional service is sincerely appreciated. Respectfully submitted, CHRISTI-\N \'X'HEELER ENGINEERING Charles H. Cl~ristian, R_GE #00215 CHC:CRB:scc cc: (6) Submitted Curtis R. Burdett, CEG #1090 I r: f . l· ' . L .L I , L L lJ t. l l . I ' ·-w CHRISTIAN WHEELER . ENGINEER.ING PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 71 APN 215-492-11 CARLSBAD, CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of a preliminary geo.tethnical investigation performed for a proposed single- family residence to b~ constructed on a vacant lot west of El Fuerte Street, in the La Costa area of the city of Carlsbad, California. Figure Number 1, on the following page, presents a vicinity map showing the location· of the property. TI1e lot is a flagpole shaped lot with the "flag" portion of the lot situated to the west of an adjacent vacant parcel (Lot 70). We understand that a single-family custom home will be constructed on the "flag" portion of the lot. The main portion of the home will be one and two stories, with a lower level garage tucked under a one-story portion on the southern side of the home. We expect that the residence will consist of masonry construction for the below grade portion and wood-frame construction for the above-grade portions. We · also expect the residence will have an on-grade. conc;rete floor slab and will be supported by conventional shallow foundations. Additional improvements will include a driveway that extends from El Fuerte Street and . . runs adjacent to the neighboring property (Lot 70) to the proposed garage, and several relatively level pads to the west of the proposed structure. Grading for the proposed home is expected to consist of cuts and fills of about ten feet and sh: feet, respectively, from existing grades. Grading for the remaining portions of the project is expected to consist of cuts and fills of about eight feet and 16 feet, respectively, from existing grades and will include cut and fill slopes up to about 15 feet in height. Additionally, several site retaining walls up to about eight feet in height are proposed. In order to augment our understanding of the proposed site development, our firm was provided with a preliminary gradillg plan prepared by LDE Consulting. A copy of this preliminary grading plan has been used as the base for our Site Plan-and Geotechnical Map, which is included herein as Plate No. 1. 4925 Mercury Street+ San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 - TABLE OF CONTENTS PAGE Introduction and Project Description ........................................................ .-...................................................... 1 Project Scope ................................................................ : ....................................................................................... 2 Findings ...... ,. · ......................................................................................................................................................... 3 Site Description ................................................................................................................................................ 3 General Geology and Subsurface Conditions ............... ; ............................................................................. 3 Geologic Setting and Soil Description ...................................................................................................... 3 Artificial Fill ................................. · ............................................................................................................ 4 Residual Soil .............................................................................................................................................. 4 Santiago Peak Volcanics ............. : ............................................................................................................. 4 Groundwater ................................................................................................................................................. 5 Tectonic Setting ............................................................................................................................................ 5 Geologic Hazards ............................................................................................................................................. 5 Ground Shaking ........................................................................................................................................... S Landslide Potential and Slope Stability ..................................................................................................... 6 Liquefaction ...................................................................... · ........................................................................... 6 Flooding ...................................... · .................................................................................................................. 6 T suna1nis ...................................................................................................... · ................................................ 6 Seiches ............................................................................................................................................................ 7 Conclusions ................ · ................... · ..... · ................................................................................................................ 7 Recommendations ........ : ....................................................................................................................................... 8 Grading and Earth\vork ...................... '. ........................................................................................................... 8 General.. .................................................................... · .................................................................................... 8 Observation of Grading: ............................................................. '. ............................................................... 8 Clearing and Grubbing ...................................................... ; ......................................................................... 8 ~~~ ~~~:;;~~~.::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::~ Processing of Fill Areas .................................................................... : .......................................................... 9 Co1npaction and Method of Filling ........................................................................................................... 9 Fill Slope Construction ............................................................................................................................... 9 Disposal of Oversize Rock ................. : ..................................................................................................... 1 O Imported Fill Material ............................................................................................................................... 11 Temporary Slopes ·······································: .............................................................................................. 11 Surface Drainage ..........................•........................... : .................................................................................. 12 Grading Plan Revie'\v ....................................................................................................... : ......................... 12 Foundations .................................................................................................................................................... 12 General. ........................................................................................................................................................ 1? Expansive Characteristics ........................................................................................................... : ............. 12 Footing Dimensions .................................................................................................................................. 12 Footing Setback ..... : .................................................... : ............................................................................... 12 Bearing Capacity ......................................................................................................................................... 13 Footing Reinforcing ............................................. ·:···················································································· 13 Lateral Load Resistance ................•.............................................. .' ............................................................. 13 Settlement Characteristics ......................................................................................................................... 13 Foundation Plan Review ................................ , ........................................................................................... 13 Foundation Excav;ltion Observation ...... ,,, ......... 1.,,. ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 13 . Seisnuc Design Parameters ........................................................................................................................... 14 On-Grade Slabs .............................................................................................................................................. 14 C\VE 2050527.03 Proposed Single-Family. Residence Lot 71, El Fuerte Street, Carlsbad, California i j - General. ........................................................................................................................................................ 14 Interior Floor Slabs .................................................................................................................................... 14 Moisture Protection for Interior Slabs .................................................................................................... 15 Exterior Concrete Flatwork. ...................................................................................................................... 15 Earth Retaining· \Valls .................................................................................................................................... 15 Foundations ................................................................................................................................................. 15 Passive Pressure .......................................................................................................................................... 16 Active Pressure .............................................................. '. ............................................................................ 16 Waterproofing and Subdrain .................................................................................................................... 16 Backfill ......................................................................................................................................................... 16 Soluble Sulfates ................................................................................................................................................ 16 Limitations ......................................................................... · ................................................................................. 16 Revie\v, Observation and Testing ...................... , ......................................................................................... 16 Uniformity of Conditions ............................................................................................................................. 17 Change in Sc?pe ................ , ................ .-........... : ............................................................................................... 17 Tune Limitations .... , ....................... : ............................................................................................................... 17 Professional Standard .......................................... , ......................................................................................... 18 Client's Responsibility ........................... , ........................................................................................................ 18 Field Explorations .............................................................................................................................................. 18 Laboratory Testing ............................................................................................................................ , ................ 19 CWE 2050527.03 Proposed Single-Family Residence Lot 71, El Fuerte Street, Carlsbad, California TABLES -Table I Table II FIGURES Figure 1 PLATES Plate 1 Plates 2-4 Plate 5 Plate 6 APPENDICES Appendix A Appendix B ATTACHMENTS Maximum Bedrock Acceleration, Page 5 Seismic Design Parameters, Page 14 Site Vicinity Map, Follows Page 1 Site Plan & Geotechnical Map Test Trench Logs Lab_oratory Test Results Retaining Wall Subdrain Detail References Recommended Grading Specifications-General _Provisions CWE 2050527.03 Proposed Single-Family Residence Lot 71, El Fuerte Street, Carlsbad, California · I I North C\v'E 2050527.03 - SITE VICINITY MAP (Adapt_ed from Thomas Brothers Maps) PROPOSED SINGLE-FAMILY RESIDENCE ELFUERTESTREET . LOT71 CARLSBAD, CALIFORNIA SITE September 2005 Figure 1 -CWE 2050527.03 September 21, 2005 Page No. 2 This report has been .prepared for-the exclusive use of Mr. Terry Johnson, and his design consultants, for specific application to the project described herein. Should the project be modified, the conclusions and recommendations presented in this report should be reviewed by Christian \Xlheeler Engineering for conformance with our recommendations and to determine if any additional subsurface investigation, laboratory testing and/ or recommendations are necessary. Our professional services have been performed, our findings obtained and our recommendations prepared in accordance with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties, expressed or implied. PROJECT SCOPE Our preliminary geotechnical investigation consisted of surface reconnaissance, subsurface exploration, obtaining representative soil samples, laboratory testing, analysis of the field and laboratory data, and review of relevant geologic literahlre. O1.1r scope of service did not include assessment of hazardous substance c~ntamination, recommendations to prevent floor slab moisture intrusion or the formation of mold ....-x.rithin the stmcture, or any other services not specifically described in the scope of services presented below. More specifically, the intent of our proposed investigation is to: a) Explore the subsurface conditions of the site to the depths influenced by the proposed construction; b) Evaluate, by laboratory tests, the engineering properties of the various strata that may influence the proposed development, including bearing capacities, expansiYe characteristics and settlement potential; c) Describe the general geology at the site including possible geologic hazards that could have an effect on the site deYelopment, and provide the seismic design parameters as required by the most recent edition of the Uniform Building Code; d) Address potential construction difficulties that may be encountered due to-soil conditions, groundwater or geologic hazards, and provide recommendations concerning these problems; e) Develop soil engineering criteria fpf site preparation and grading,; f) Provide design parameters for 1.1nrestrained arid restrained retaining walls; C\v'E 2050527.03 -September 21, 2005 Page No. 3 g) Recommend an appropriate foundation system for the type of structures anticipated and develop soil engineering design criteria for the recommended foundation design; h) Present our professional opinions in this report, which includes in addition to our· conclusions and·recommendations, a plot plan, exploration logs and a summary of the laboratory test results . . Although tests for the presence of soluble sulfates were performed as part of the scope of our services, it should be understood Christian Wheeler Engineering does not practice corrosion engineering. If such an analysis is considered necessary, we recommend that th_e client retain an engineering firm that specializes in thi~ field to consult with them on this matter. · The results of these tests should only be used as a guideline to determine if additional testing and analysis is necessary. FINDINGS SITE DESCRIPTION The subject site is a Yacant, f1'lgpole-shaped parcel ofland located on the western side of El Fuerte Street, in the La Costa area of the city of Carls.bad, California and is identified by Assessor's Parcel Number 215-492-11 and as Lot 71. The "pole" portion of the lot fronts on El Fuerte Street and extends along the northern side of the adjacent Lot 70 to the "flag" portion of the lot, which is located to the west of the adjacent Lot 70. Topographically, the lot generally slopes moderately towards the southwest with the on-site elevations ranging from a low of approximately 197 feet at the southwest corner to a high of approxin1ately 260 feet in the northeast portion of the site. In terms of vegetation, the site is covered by mostly by low-lying \Veeds with a small amo·unt'of brush along the· southern property line. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located near the boundary between the Foothills Physiographic Province and tl1e Coastal.Plains Physiographic Province of San Diego County. Based on the -results of our subsurface explorations and analysis of readily available, pertinent geologic literature, the site was dete1mined to be underlain by ll relatively thin layer of fill and/ or residual soils overlying Jurassic/Cret'lceous-age metaYcolcanic rock minor amouqts of associated sedin1entary rock. These materials are described below: i ' . C\VE 2050527.03 e. September 21, 2005 -Page No. 4 ARTIFICIAL FILL (Qat): An approximately 3½-foot-thick layer of fill material was encountered within our exploratory trench T-1, which was excavated in the northeastern portion of the "flag" area. The fill material consisted of medium to dark brown, clayey gravel (GC) that was damp and loose in consistency. Based on our experience with similar soil types, we expect that the fill has a "low" expansion potential, lo\Y to moderate strength parameters, and low to moderate settlement potential In its existing state, the fill is typically variable iri consistency and is tl1erefore considered unsuitable to support new fill and/or settlement-sensitive improvements: This material, howe~er, may be incorporated into structural fills provided it is free of organic debris. RESiDUAL SOIL: An approximately 1 ½-to· 5½-foot-iliick layer of residual soil was encountered within each of our exploratory ~enches. The residual soils typically consisted of an approximately · one-foot-thick layer of medium brown, damp, loose, silty sand (Sl'Y.[) topsoil over an approximately 1 ½-to 4-foot-thick layer of medium reddish-brown, damp to moist, medium stiff, sandy clay (CL) subsoil; however, topsoil was not encountered with trench T-1. Based on our laboratory testing and experie1ice with similar soil types, we e::,,.-pect tl1at the topsoil has a "low" expansion potential while the subsoil has a "very high" expansion potential.. \Ve also e::,,.-pect that both tl1e topsoil and subsoil have low to moderate strength parameters and low to moderate settlement potential. In their natural state, the residual soils are typically variable in consistency and are tl1erefore consi~ered unsuitable to support fill and/ or settlement-sensitive improvements. The sandy topsoil material, however, may be incorporated into structural fills provided they are free of organic ?ebris. The e::,,.-pansive subsoils will need to be mixed with otl1er on-site sandy soils prior to being placed as.fill, to make a nondetrimentally e::,,.-pansive rni'i:ture of soil, or be placed qnly in landscape areas where no concrete flat work is planned. SANTIAGO PEAK VOLCANICS (Kjsp): Below the fill and residual soils, the site is ultimately underlain by Jurassic/Cret'tceous-age metavolcanic rock and minor amounts of associated sedimentary rock identified as tl1e Santi.ago Peak Volcanics. TI1e sedimentary rock was noted to consist of medium reddish-brown and µght gray, damp, den_se to very dense, silty sand (S:tv:1) tl1at was generally moderately- to well-cemented and was modei;ately fractured in some areas. The sedimentary rock has relatively high strengtl1 parameters and a lo\v expansiqn potential in its natural and compacted states. The metavolcanic rock was noted to consist of medium reddish-brown and medium gray, damp to moist, dense to very dense, silty gravel (G:tv:1), with sand and cobble. TI1e sedimentary rock has relatively high strength parameters and a low expansion potential in its natural and co~pacted states. The sedimentary material and tl1e metavolcanic material are suitable in tl1~ir present condition to support fill and/ or settlement- sensitive improvements and may also be used as structural fill. ! ' C\v'E 2050527.03 -September 21, 2005 -Page No. 5 GROUNDWATER: Groundwater was not encountered in any of our subsurface explorations and we do not anticipate any groundwater related problems during or after construction. It should be recognized, however, that minor groundwater seepage problems may occur after development of a site even where none were present before development. These are usually minor phenomena and are often the result of an alteration of the permeability-characteristics of the soil, an alteration in drainage patterns and an increase in irrigation water. Based on the permeability characteristics of the soil and the anticipated usage of the development, it is our opinion that any seepage problems which may occur will be minor in extent. It is further our opinion that these problems can be most effectively corrected on an individual basis if and when _ they develop. TECTONIC SETTING: No major faults are known to traverse the subject site but it should be noted that much of Southern California, including the San Diego County area is characterized by a series of Quaternary-age fault zones which typically consist of several individual, en ecl)elon faults that generally strike in a northerly to nor~r,vesterly direction .. Some of these fault zones (ar_id the individual faults within the zones) are classified as active while others are not currently considered to be active, according to the criteria of the California Division of 1'-fines and Geology. Active fault zones are tl10se which haYe shown conclusive evidence of faulting during the Hdlocene Epoch (the most recent 11,000 years). A reYiew of available geologic maps indicates that the active Rose Canyon Fault Zone is located appro~a:tely 10½ kilometers west of the subject site. Other active fault zones in the region that could pos~ibly affect the site include the Newport Inglewood and Coronado Bank Fault Zones to the west and southwest, respectiYely, and the Earthquake Valley, Elsinore and Sa_nJacinto Fault Zones to the east. GEOLOGIC HAZARDS GROUND SHAKING: A likely geologic hazard to affect the site is-ground shaking as a result of movement along one of the major active fault zones mentioned above. The maximum ground accelerations that could affect the site, based on our Deteq:ninistic _Seismic Hazard Analysis (DSHA), are summarized in the following Table I. CWE 2050527.03 --September 21, 2005 -Page No. 6 TABLE I: MAXIMUM GROUND ACCELERATIONS Fault Zone Distance Maximum Magnitude Maximum Ground Earthquake Acceleration Rose Canyon 10.5 km · 6.9 magnitude 0.25 g Newport-Inglewood 18km 6.9-mal2Uitude 0.17 g Coronado Bank 35km 7.4 magnitude 0.14g Elsino~e -T ulian 38km 7.1 magnitude 0.11 g Earthquake Valley "63km 6.5 magnitude 0.06g San Jacinto (Anza) 75km 7.2 magnitude 0.07 g ·Probable ground shaking levels at the site could range from slight to moderate, depending on such factors as the magnitude of the seismic event and the distance to the epicenter. It is likely that the site will experience the effects of at least one moderate to large earthquake during the life of the proposed improvements. LANDSLIDE POTENTIAL AND SLOPE STABILITY: As part of this investigation we reviewed the publication, "Landslide Hazards in the Southern Part of the San Diego Metropolitan Area" by Tan, 1995. This reference is a c~mprehensive study that classifies San Diego County into areas of relative landslide Sl!sceptil;,ility. The subject site is located in Relative Landslide Susceptibility Area 3-1. Area 3 is considered to be "generally susceptible" to slope failures; Areas within Subarea 3-1 are considered at or near their stab~ty limits due to steep slopes and can be expected to fail locally when adversely modified. Sites within this classification are located outside the boundaries of known landslides _but may contain observably unstable _slopes that may be underlain by weak materials and/ or ad,rerse geologic structure. However, based on the very competent nature of the sedimentary rock that underlies the site and the proposed slope inclinations on- site, it is our professional opinion and judgment that the potenti.al for landsliding at the subject site is low. LIQUEFACTION: !he near-surface soils encountered at the site are not considered to be susceptible to liquefaction due to such factors as soil density, grain-size distribution and _the absence of shallow groundwater conditions. FLOODING: .i:\,s delineated on the referenced Flood Insurance Rate Maps prepared by the Federal Emergency Management Agency (1051F), the site is located outside of the boundaries of both the 1O0-year and 500-year flood zones. TSUNAMIS: Tsunamis are great sea waves produced by submarine earthqu_akes or volcanic eruptions. The site is not subject to risk from tsunamis. -C\\7E 2050527. 03 September 21, 2005 Page No. 7 SEICHES: Seiches are periodic oscillations iI} large bodies of water such. as lakes, harbors, bays or reservo1rs. The site will not be affected by seiches. CONCLUSIONS It is our opinion and professional judgment that no geotechnical conditions exist on the subject property that would preclude the construction of the proposed residence and improvements provided the recommendations presented herein are followed. The following are the most significant geotechnical conditions to adversely affect the proposed construction; • Our ihvestigation has indicated that the site is ultimately underlain by dense to very dense metavcolcanic rock with minor amounts of associated sedimentary rock, but is mantled by an up to C 5½-foot-thick layer of relatively loose residual _soil and fill material that are considered unsuitable in their present condition to s~pport fill and/ or settlement-sensitive improvements. As such, any surficial soil that is not removed by the pl:mned grading will need to be overexcavated in tl1e areas to support fill and/or settlement-sensitive improvements and be replaced as properly compacted fill. • The existing residual soil was determined to be very highly expansive. As such, tl1is material will . . need to be mixed witl1 the sandy portions of the on-site soil to create a nondetrimentally expansive mix prior to placement as structural fill, or be .placed only in landscape areas where no concrete flat work is planned. • Based_bn-the proposed grading plan, the residence will supported by fills of varying thickness. Additionally, we anticipate that altl1ough the metavcolcanic rock with minor amounts of associated seditnentary rock can be excavated to the proposed depilis using heavy grading equipment, it will be difficult to excavate for foundations and/ or utilities in this material using lightweight trenching equipment. -Based on these conditions, it will be necessary to undercut the cut portions of the proposed pads during grading to mitigate tl1e potential for differential settlement and so that it will be possible to use normal trenching equipment during the construction of tl1e home. The site is located in an area that is relatively free of geologic hazards tl1at will have a significant effect on the proposed development .. The most significant geologic hazard that could affect the site is ground shaking due to seismic activity along one of the regional acti,:e; faqJt~. Jiowever, construction in accordance with the I i \, I I 1 " -C\v'E 2050527.03 September 21, 2005 -Page No. 8 requirements of the Uniform Building Code and other governmental regulations should provide a level of life-safety suitable for the type of development proposed. RECOMMENDATIONS GRADING AND EARTHWORK GENERAL: All grading should conform to the guidelines presented in Appendi.-: Chapter A33 of the Uniform Building Code, the minimum requirements of City of Carlsbad, and the recommended Grading Specifications and Special Provision_s attached hereto, except where specifically superseded in the text of thi_s report. Prior to grading, a representative of Christian Wheeler Engineering should be present at the pre-construction meeting to provide additional grading guidelines, if necessary, and to review the earthwork schedule. OBSERVATION OF GRADING: Continuous observation by the Geotec,hnical Consultant is essential during the grading operation to confirm conditions anticipated by our investigation, to allow adjustments in design criteria to reflect actual field conditions exposed, and to determine that the grading proceeds in general accordance with the recommendations contained herein. CLEARING AND GRUBBING: Site_gra:ding should begin with the removal of all existing vegetation and other _deleterious materials from the portions of the site that will be graded and/ or will receive improvements. Discing of the vegetation into the existing surficial soil is not an acceptable method of brush and grass removal, and may result in the surficial material being unsuitable for use as structural fill. All vegetation· and other deleterious debris resulting form the clearing and grubbing should be disposed of off-site. SITE PREPARATION: After clearing and grubbing, the site preparation will generally consist of the . ' . removal of unsuitable surficial soils that are not removed by the planned grading and, where necessary to achieve the pla~111ed grades, replacing that material as properly compacted fill. The removals should extent to the contact.with competent sedimentary rock. The sedimentary rock was typically encountered at depths ranging from 3½ to 5½ feet belo,~ the existing grades, but may be deeper in localized areas. The excavated material should be replaced as properly compacted-fill in accordance with ·the· recommendations presented in the "Compaction and Method of Filling" section of this report. The areas cleaned out of unsuitable soils should be approved by the geoteclinical engineer prior to replacing any of the excavated soils. · Additionally, the existing subs~il on-site was found to-h~ve a "very high" Expansion Index. Based on this condition, prior to placement as fill, the.overexcavated subsoil material will need to be mixed with other on- ---C\VE 2050527. 03 September 21, 2005 Page No. 9 site sandy material to create a mixture that has an Expansion Index of 50 or less, or be placed lonely in landscape areas where no concrete flatwork is. planned .. PAD UNDERCUTS: Based on the proposed grading, the residence will be supported partially by cut and partially by fill. Additionally, we anticipate that very dense sedimentary rock will be exposed in the cut . portions of the building pad. As such, we recommend that the cut portions of the pad be undercut to a depth of at least three feet below the pad grade or two feet below the lowest bottom of footing elevation (including retaining wall keyways), whichever depth is greater. This will allow the foundation and on-site utility trenches to be excavated using normal trenching equipment. The overexcavated area should be sloped at an inclinatio;1 of at least two percent towards the south in such a manner that water does not become trapped in the oYerexcavated zone. The overexcavated soils should be replaced in the excavation as structural fill, compacted to at least 90 percent of maximum dry density. PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constructing any new improvements in areas that have been cleaned out to receive fill, the exposed soils should be scarified to a depth of 6 inches, moisture conditioned, and compacted to at least 90 percent relative compaction. COMPACTION AND METHOD OF FILLING: Structural fill should be compacted to a relative compaction of at least 90 percent of maximum dry density as determined by ASTM Laboratory Test D1557- 91. Fills shou_ldbe placed at or slightly above optimum.moisture content, in lifts six to eight inches thick, with each lift compacted by mechanical means. Fills should consist of approved earth material, free of trash oi: debris, roots, vegetation, or other materials determined to be unsuitable by our soil technicians or project geologist. Fill material should be free of roc~s or lumps of soil in excess of twelve inches in maximum dimension. However, in the upp_er two feet of subgrade, no rocks or lumps of soil in excess of si.."\: inches should be allowed. Based upon the results·of our subsurface exploration and laboratory testing, all of the on- site soils appear suitable for use as fill material. U~t:y trench backfill within five feet of the prop~sed structures· and beneath driveways, concrete flatwork, and pavements should be compacted to a minimum of 90 percent of its maximum dry density. FILL SLOPE CONSTRUCTION: Based on the preliminary grading plan, we anticipate that fill slopes required for the site will be less than 15 feet in height. All fill slopes should be construc"red at an inclination of 2:1 or flatter Q101-izontal to vertical). Compaction ~f ~lppe~ should be performed by back-rolling with a sheep~foot compactor at vertical intervals of four feet or less as the fill is being placed, and track-walking the ' ' . ! .l ' CWE 2050527.03 September 21, 2005 Page No. 10 face of the slope when the slope is completed. As an alternative, the fill slopes may be overfilled by at least three feet and then cut back to the compacted core at the design line and grade. Fills should be benched into all temporary slopes and into competent natural soils when the natural slope is steeper than an ~clination of_5:1 ~1orizontal to vertical). Keys should be constructed at the toe of all fill slopes. The keys should extend at least 12 inches into firm natural ground and should be sloped back at least two percent into the slope area. · Keys should have a minimum width of 10 feet. DISPOSAL OF OVERSIZE ROCK: Oversize rock in grading operations is defined herein as rocks over 12 inches in diameter. The following provides our recommendations for placement of oversize rock in structural fills. !fit is not possible to place the oversize material as described below, it will be necessary to place the material in landscaped areas or break the material into particles of less than 12 inches in diameter and inco1-porate them into the proposed structural fill. 1) No oversize rock should be placed within ten (10) feet, measured horizontally, from the face of fill slopes. 2) No mrersize rock should be placed within ten (10) feet ~f finish pad grade in the fiUportions of the site. In addition, no rock should be placed within two (2) feet of the bottom of the lowest utilities. 3) Oversize rock up to two feet in average dimension may be placed in unifonn _lifts across the fill area in an unnested manner. Prior· to placing each subsequent lift, decomposed granitics with a Sand EquiYalent (SE) of at least 25 should be spread over the rock. This material should be fl<:>oded into the voids between the rocks and should cover the rock by at least six inches. The top of each lift should be smoothed out with a dozer· and be wheel-rolled with a loaded scraper or other suitable heavy compaction equipment approYed by the geotechnical consultant. 4) Rocks two to four feet in average dimension may be plac_ed in windrows. The windrows should be at least 12 feet apart to allow compaction equipment to move between the rows. As the fill is brought up between the windrows, decomposed granitics with a SE of at least 25 should be flooded between and around the rocks to fill all voids. There should be at least one foot of cover over the top of wipdrows befi::>l;c; the P.;xt windrows are started. TI1e windrows placed above previously placed windrows should be staggered half way between the lower windrows. ! I., --CWE 2050527.03 September 21, 2005 Page No. 11 ' 5) Rocks larger than two feet in average dimension may also be individually placed. This placement · should consist of excavating a trench or ditch· to a depth of at least one-third the diameter of the rock and rolling the rock into the excavation. Such rocks should be spaced at least 12 feet apart in order to allow compaction equipment to move around the rock. As the fill is brought up around the rock, decomposed granitics _with a SE of at least 25 should be flooded against the lower third of the rock. Above this, the compaction equipment should compact the fill against and over the rock. 6) Sufficient compac;tion effort should be made such that all fill material placed around and between the oversize rocks is compacted to at least 90 percent of maximum dry density as determined by ASTM D1557-9l. 7) , The placement of all fill and all oversize _rock disposal, including flooding, should be continuously observed by a representative of Cl~ristian Wheeler Engineering. TI1is is also required to allow us to provide a professional opinion after grading that the fill and rock disposal was. done in accordance with the recommendations contained herein. IMPORTED FILL MATERIAL: Imported soils should be evaluated and approved by the geotechnical consultant prior to being imported. At least two working days notice of a potential import source should be given to the Geotech11ic~l Consultant so that appropriate testing can be accomplished. The type of material considered most desirable for import is granular material containing some silt or clay binder, which has an expansion index ofless than 50, less than 25 percent larger than the standard #4 sieve, and less than 25 percent .finer than ~he standard # 200 sieve. TEMPORARY SLOPES: We anticipate that temporary excavation slopes will less than about 10 feet in height. For unconfined excavations, the lower 4 feet of the excavation may be cut vertically and the portions of the excavation above 4 feet should be slbped at an inclination of 0.75:1 (H:V). If deeper excavations are required, specific recommendations will be provided in the·field when the soils and site condi~ons can be identified. Deep, temporary confined excavations, such as for underground utilities, should use sloping sides, shoring, or "trench boxes" during construction, or any other apprmred construction technique to assure stability of the excavations. The contractor is solely responsible for designing and constructing stable, temporary excavations and may need to shore, slope, or bench the sides of trench excaYations as required to maintain the stability of the excavation sides where the friable sands are exposed. The contractor's "responsible person", as defined in C\v'E 2050527.03 September 21, 2005 Page No. 12 the OSHA Construction Standards for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety process. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal ' ·s~fe.~ regulations. •.: ,, . ' SURFA¢E _DRAINAGE: The ground around the proposed structure should be graded so that surface . . . ~ . water flows--.r~pidly away from the structure without ponding. In general, we re~ommend that the ground· adjacent to ~he s~~~re slope away at a gradient of at least two percent. Densely vegetated areas where runoff can be impaired should have a minimum gradient of at least five percent within the first three feet from the structure. Gutters and downspouts should discharge into controlled drainage devices. GRADING PLAN REVIEW: The final grading plans should be submitted to this office for review in order to ascertain that the recommendations of this report have been implemented, and that no additional recommendations are needed due to changes in the anticipated development plans. FOUNDATIONS GENERAL: Based on our findings and engineering judgments, the proposed structure may be supported by conv:entional continuous and isolated spread footings. The following recommendations are considered the minimum based on soil conditions and are not intended to be lieu of structural considerations, All foundations should be designed by a qualified structural engineer. EXPANSIVE CHARACTERISTICS: Provided tl:i,e recommendations presented in this report are followed, -we anticipate that special foundation design for heaving soils will not be necessary. FOOTING DIMENSIONS: It is our opinion that the propdsed structure may be supported by conventional continuous and isolated spread footings. Spread footings should be embedded at least 18 inches below finish pad grade for one-and two-story portions of the residence. Continuous footings should have a minimum width of 12 and 15 inches for one-and two-story portions of the residence, respectively. Isolated spread footings should have a minimum width of 24 inches. Retaining wall footings should-have a minimum embedment of 18 inches below the lowest adjacent grade and should have a minimum width of 24 inches. FOOTING SETBACK: \v'here retaining walls are proposed at the top of slopes, we recommend that a minimum horizontal setback of 8 feet be provided from the outer edge of the footing to the adjacent slope face. The footing setback distance from the top ?f the slope may be achieved by using deepened footings. --C\VE 2050527.03 Septe!nber 21, 2005 PageNo.13 Footing setback is measured from competent soil and should neglect any loose or soft native soils that may occur at the top of a natural slope. Footings planned under the specified setbacks should be provided specific review by the Geotechnical Consultant prior to construction. BEARING CAPACITY: Spread footings with an embedment of 18 inches and a ·width of 12 inches may be designed using an allowable soil bearing pressure of 2,500 pounds per square foot (psf). Th.is value may be increased by 800.psf for each additional foot of "efl:1-bedment depth and 250 psf for each additional foot of width, up to a maximum of 4,000 ps£ U1e bearing value may also be .increased by one-third for combinations of temporary loa~s such as those due to wind or_ seismic loads. FOOTING REINFORCING: Reinforcem~nt requirements for foundations should be provided by a structural engineer. However, based on the expected soil conditions, we recommend that the minimum reinforcing for continuous footings consist of at least two No. 5 bars positipned three inches above the bottom of the footing and two No. 5 bats positioned approximately two inches below the top of the footing. LATERAL LOAD RESISTANCE: Lateral loads.against foundll.tions may be resisted by friction between the bottom of the footing and the supporting soil, and by the passive pressure against the footing. The coefficient of friction between concrete and soil may be considered to be 0.35. The passive resistance may be considered to be equal to an equivalent fluid weight of 350 pounds per cubic foot. These values are based on the assumption that the footings are poured tight against undisturbed soil. If a combination of the passive pressure and friction is used, the friction value should be reduced by one-third. SETTLEMENT CHARACTERISTICS: The anticipated total and differential settlement is expected to be less than about one inch and one inch over forty feet, respectively, provided tl1e recommendations presented in this report are followed. It should be rec;:ognized that minor cracks normally occur in concrete slabs and foundations due to concrete shrinkage during curing or redistribution of stresses, therefore some cracks should be anticipated. Such cracks are not necessarily an indication of excessive vertical movements. FOUNDATION PLAN REVIEW: The foundation plans should be submitted to this office for review in order to ascertain that the recommendatio_ns of this report have been implemented, and that no additional recommendations are needed due to changes in the anticipated construction. FOUNDATION EXCAVATION OBSERVATlO~; All footing excavations should be observed by Christian \v'heeler Engineering prior to pfacing reinforcing steel to determine if the foundation recommendations presented herein are followed and that the foundation soils are as anticipated in the CWE 2050527.03 Sep_tember 21, 2Q05 PageNo.14 preparation of this ;eport. All footing excavations should be excavated neat, level, and square. All loose or unsuit_able material should be removed prior to the placement of concrete. SEISMIC DESIGN PARAMETERS Based on a maximum magnitude (Mmax) earthquake of 6.9 along the nearest portion of the offshore segment of the Rose Canyon Fault Zone, the Maximum Ground Acseleration at the site is estimated to be approxima,tely 0.25 g. For struc~ral design purposes, a damping ratio not greater than 5 percent of critical dampening is recommended. Soil Profile Type Sc is recommended (UBC.Table 16-J). Based upon the location of the site greater than 10 kilometers from the Rose Canyon Fault Zone (Type B Fault), Near Source Factors ·Na equal to 1.0 and N,. equal to 1.0 are also applicable. These values, along with other seismically related design parameters from the Uniform Building Code (UBC) 1997 eqition, Volume II, Chapter 16, utilizing a Seismic Zone 4 are presented in the following table. TABLE II: SEISMIC DESIGN PARAMETERS UBC -Chapter 16 Seismic Recommended Table No. Parameter Value 16-I Seismic Zone Factor Z 0.40 16-l Soil Profile Type Sc 16-Q Seismic Coefficient c. 0.40N. 16-R Seismic Coefficient C,. 0.56 N,. 16-S Near Source Factor N. 1.0 16-T Near Source Factor N" 1.0 16-U Seismic Source Tvpe B ON-GRADE SLABS GENERAL: It is our understanding that the floor system of the proposed structure and garage will consist of concrete slabs-on-grade. The following recommendations are considered the minimum slab requirements based on the soil conditions and·are not intended in lieu of structural·considerations. INTERIOR FLOOR SLABS: For conventional slabs, the minimum slab thickness ;hould be four inches (actual) and the slab should be reinforced with at least No. 3 bars spaced at 18 inches on center each way. Slab reinforcement should be supported on chairs such that the reinforcing bars are positioned at mid-height in the floor· slab. The slab reinforcement should e~t~nd ~t9 the perimeter footings at least six inches. The garage slab may be constructed independent from the garage perimeter footings, but should have a felt strip --C\VE 2050527.03 September 21, 2005 Page No. 15 between the slab and footing. If the garage slab and footings are constructed monolithically, the reinforcement should extend into the perffi:1eter footing at least six inches. MOISTURE PROTECTION FOR INTERIOR SLABS: Historically, it has been a construction standard to install a moisture/vapor retarder system below interior on-grade slabs where moisture-sensitive floor covering are ~nticipated. The purpose of the moisture/vapor retarder is to attempt to minimize the transmission of moisture up through the concrete slab from sources below the slab. It can be noted that there is no known construction method that will insure that no moisture will migrate up though on-grade floor slab, and that there will always be some amount of moisture migration into the air space above on-grade floor slabs. 'The industry standard for·a moisture/vapor retarder system is to-place a four-inch layer of clean, coarse sand or crushed rock below on-grade concret~ floor slabs. If sand is used, which is the most common subslab material, it should have less than ten percent and five percent passing the No. 100 and No. 200 sieves, respectively, in order to provide a capillary break b~tween the underlying soil and the concrete slab. In addition, a 15-mil polyethylene membrane, such as Stago-\'vrap, should be placed directly over the sand or rock blanket and the slab concrete should be placed directly over the membrane. The membrane should be placed in accordance with the r~commendation and consideration of ACI 302, "Guide for Con·crete Floor and Slab Construction" anq ASTM E1643, "Standards Practice for Installation of Water Vapor Retarder Used in Contact with Earth or Granular Fill Under Concrete Slabs". In-addition, concrete mixes can be designed to reduce the permeability of tl1e concrete, and thus, reduce the amount of moisture migration up into the air space above the on-grade concrete slab. If desired, we can provide mix design recommendations to help minimize the concrete permeability. EXTERIOR CONCRETE FLATWORK: Exterior slabs should have a minimum thickness of four inches. Re~forcement should be placed in exterior concrete flatwork to reduce_ the potential for cracking and differential movement. Control joints should be placed in exterior concrete flatwork to help control the location of shrinkage cracks. Spacing of control joints should be in accordance with the American Concrete Institute specifications. EARTH RETAINING WALLS FOUNDATIONS: _Specific recommendations for retaining wall foundations are presented in the "Foundations" section of this report. C\'v'E 2050527.03 September 21, 2005 Page No. 16 PASSIVE PRESSURE: The passive pressure for the prevailing soil conditions may be considered to be 350 pounds per square foot per foot of depth. This pressure may be increased one-third for seismic loading. The coefficient of friction for conc_rete to the on-site soil may be assumed to be 0.35 for the resistance to lateral movement. \Vhen combining frictional and passive resistance, the friction should be reduced by one-third. The upped2 inches of exterior retaining wall footings should not be included in passive pressure calculations where abutted by landscaped areas. ACTIVE PRESSURE:·The active soil pressure for the design of "unrestrained" and "restrained" earth retaining ~tructures with a level, nondetrimentally expansive soil backfill may be assumed to be equivalent to the pressure of a fluid weighing 35 and 55 pounds per cubic foot, respectively. An additional 13 pounds per cubic foot should be added to the above value for 2:1 Q1orizontal to vertical) sloping backfill. These pressures do not consider any other surcharge. If_any are anticipated, this office should be contacted for the necessary increase in soil pressure. These values assume a drained backfill condition. WATERPROOFING AND SUBDRAIN: Waterproofing details should be provided by the project architect. A suggested wall subdrain detail is provided on the attached Plate Number 6. We recommend that the Geotechnical Co11sultant observe all retainjng ~all subdrains to verify proper construction. BACKFILL: All backfill soils should be compacted to at least 90 percent relative compaction. Expansive or clayey soils with an Expansion Index greater than 75 should not be used for backfill material. The wall should not be backfilled until the masonry has reached an adequate strength. SOLUBLE SULFATES . The water soluble sulfate content was determined for a representative soil sample from the site in accordance with California Test Method 417. The result of this test indicated that the representative soil sample had a soluble sulfate content of 0.003 percent. Soils with a soluble sulfate content ofless than 0.1 percent are considered to be negligible and no special recommen?ations are needed. LIMITATIONS REVIEW, OBSERVATION AND TESTING The recommendations pr~sented in thi_s report are contingent upon our review of final plans and specifications. Such plans and specifications should be made available to the geotechnical engineer and -C\'XIE° 2050527.03 September 21, 2005 Page No. 17 engineering geologist so that they may review and verify their compliance with this report and with the Unifo1n_i Building Code. It js recommended that Christian \Vheeler Engineering be retained to provide continuous soil engineering services during the _earthwork operations. This is to verify compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior.to start of construction. UNIFORMITY OF CONDITIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface e)...-ploration locations and on the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/ or cut and fill slopes may be influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the geotechnical engineer so that he may make modifications if necessary. CHANGE IN SCOPE This office should be advised of any changes in the project scope or proposed site grading so that we may determine if the recommendations contained herein are appropriate. This should be verified in writing or · modified by a written addendum. TIME LIMITATIONS The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur. with the passage of time, whether they are due to natural processes or the work of man on this or adjacent properties. In addition, changes· in the Standards-of-Practice and/ or Government Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two years without a review by us verifying the suitability of the conclusions and recpmm~11qatjons. ' I • , • ' ~ . j l ·f C\VE 2050527.03 -September 21, 2005 -Page No. 18 PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skill ordinarily exe~cised by members of our profession currently practicing under similar conditions and in the same locality. The client reco~z.es that subsurface conditions may vary from tl1ose encountered at the locations where our borings, surveys, and explorations are ~ade, and that our data, interpretations, and recommendations be based solely on the information obtained by us. We will be responsible for those data, interpretations, and recommendations, but shall not be responsibJe for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any · kind whatsoever, expre;s or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or written reports or findings. CLIENT'S RESPONSIBILITY It is the responsibility of the Client, or his representatives, to ensure that the information and reconunendations contained herein are brought to tl1e attention of the structural engineer and architect for the proje~t _and in~orporated into the project's plans and specifications. It is further their responsibility to take the necessary measures to insure that the contractor and his subcontractors carry out such recommendations during construction. FIELD EXPLORATIONS Three _subsurface e:i...-plorations were made at the locations indicated on the attached Plate Number 1 on July 5, 2005. These explorations consisted of test trenches excavated by a Case 580L backhoe using an 18-inch bucket. The fieldwork was conducted under the observation of our engineering geology personnel. The explorations were carefully logged when made. The test trench logs are presented on the following Plate Numbers 2 through 4_. The soils are described in accordance with the Unified Soils Classificati<?n System. In addition, .a Yerbal textural description, the wet color, the apparent moisture and the density or consistency are provided. The density of granuiar soils is given-as very loose, loose, medium dense, dense or very dense. The consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff, or hard. Disturbed and "relatively undisturbed" chunk samples of typical" and representative soils were obtained and tJ:ansported to our laboratory for testing. ! l' --CWE 2050527.03 September 21, 2005 PageNo.19 LABORATORY TESTING Laboratory tests were performed in accordance with the generally ac~epted American Society for Testing and Materials (ASTM) test methods or·suggested procedures. As such, the test results for all three lots are presented on the attached Plate No. 5. A brief description of the tests performed is presented below: a) CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The final soil·classifications are in accordance with _the Unified Soil Classification System. b) MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for representative soil samples. This information was an aid to classification and permitted recognition of variations in material consistency with depth. The dry unit weight is determined in pounds per cubic foot, and the in-place moisture content is determined as a percentage of the . soil's dry weight. The results are summarized in the attached trench logs. c) COMPACTION TES1: The maximum dry density and optimum moisture content of typical soils were ~etermined in the laboratory in accordance with ASTM Standard Test D-1557, Method A. The resu_lts of this test are presented on Plate No. 5. d) DIRECT SHEAR TEST: Pirect shear tests were performed on representative samples of the on- site material to determine the failure envelope based on yield shear strength. The shear box was designed to accommodate a sample having a diameter of 2.375 inches or 2.50 in~hes and a height of 1.0 inch. The samples were saturated and tested at different vertical loads. The shear stress was applied at a constant rate of s_train of approximately 0.05 inch per minute. The results of these tests a~e presented on Plate No. 5. e) EXP ANSI ON INDEX TEST: Expansion Index testing was performed on a remolded representative sample of th~ on-site soil. The testing was performed on the portion of the sample passing the #4 standard sieve. The sample was brought to optimum moisture content and then dried back to a constant moisture content for 12 hours at 230 ± 9 degrees Fahrenheit. The specimen was theµ compacted in a 4-inch-diameter mold in two equal layers by means of a tamper, then trimmed to a final height of 1 ·inch, and brought ·to a saturation of approximately 50 percent. The_specimen was placed in a consolid01p.et~r with porous stones at the top and bottom, a total normal load of 12.63 pounds wa_s placed (144.7 psf), apd the sample was allowed to consolidate for a period of lO minutes. The sample was saturated, and the change in vertical movement was I l ' l i l i l.. I I --C\VE 2050527 .03 September 21, 2005 Page No. 20 _recorded until the rate of expansion became nominal. The expansion index is reported on Plate No. 5 as the total vertical displacement times 1000. D SOLUBLE SULFATES: The soluble sulfate content was determined for samples of soil likely to be present at the foundation level. Th~ soluble sulfate content was determined in accordance with California Test Method 417. The results are presented Plate No. 5. ·········· '\ l I 51111 0 ~~' ~ l~_;, \\; '\":3 11; l1 111 1\l\ ___ ,.. .-·111 PAD 210 . -. . ., ·--..... -·' . ·-· -~p ~ ·· ~.(T-1 11 FFE ~g PAD 238 . FFE 226 .. -··· ',.' KJsp -·· . ,,• .. , ... LEGEND I IT-3 __ .P,P.P_ROXIMATE.:TEST.TRf=NCH. L,OCATION_. .Qa1 ARTIFICIAL FILL OVER SANTIAGO PEAK VOLCANICS I KJ$P KJsp --- SANTIAGO Pl;AK VOLCANICS -GEOLOGIC CONTACT NOTE: 'SURFICIAL·soii.. LAYER LESS THAN 2 FEET THICK ·ARE NOT. MAPPED . 1} w CHRISTIAN WHEELER ENGINEERING 492S Mercurv Street• San Die110, CA 92111 • 858-496-9760 • FAX 858-496-9758 PROPOSED SFR LOT 7.1 . BY: CHC/SCG/HC DATE: 09-14-05 20· ,.,. ,o· ,. a· zo· -!<>' GRAPHIC SCALE: /"z20" JOB NO.: 2050527.3 PLATE NO.: 1 ,_,_,. ___ ,_._ M"'" , .. ,, ___ ,.,_, ____ ,_ •M-·----•••m••• ....... ., .. , __ ,,. ,,,.,., -•• '"-"'"'' ••• "••••• ,1,, ..... L• 20.ZJ' \ \ ,lo,2::6'.i' =~-, ~ ~.,,,, ~\, FFE 243.0 .._ FFE 228 I •I PAD 228 N 7~w-· "12..!ll"f 1· COHCR£T DRll£11'AY .\ ;· ... "" ....... -... """"·-·-·7 .... ~-. -.. I I I . I I /u Jl !JJ. l1: -;i /;;j .. I \~ . UJ IUJ ·1~ ~ ::> I~ . UJ I I I I 'AS BUILT' RC£___ EXP ___ _ REV!E\IED BY• DAT£. INSPECTOR DA TE jSiiffil CITY OF CARLSBAD 'SHEETS' l-1---1,r---+-1---------,-t--,---11i---;-1--t1---l1 ~ PLAN~N:i:.R~~~:~~E 4 I I I :1 I I I IJT!TLESHEET I I I • I I I I I l~PPROVED l----ll--+--------------'-,~+---f---+--+----11 · .fll'l:5T Ui:ST, PE Mlll/IIU/TITT ----, t:~~;:t~:;.~t::::::::::::::::::::::::::~:=t~~~=t;~~=~~~~=t~;~~ CITY ENGINEER PE EXPIRES DA TE t' DATE INITIAL, DATE INITIAL DATE INITIAL DWN BY;. _.zss,_ I PROJECT NO. I DRAW,NG NO. <•OOH££• or '"""" REVISION DESCRIPTION Ol!O ......,v.._ CITY APPROYAl. ~~ g~; ~ PROJECT NO. OR•MHC NO. .&. r I I ; 1 I ·I l ' j l J _______________ ___,_, _____ ____, . LOG .OF TEST TRENCH -NUMBER T-1 Date Excavated: 7/5/2005 Equipment: Case 580L Backhoe Existing Elevation: Finish Elevation: 'C' (I) ,1l ..__, ~ Cl 1 2 3 4 (j 0 ....:l u >-4 ::c: p.. -~ (j SUMMARY OF SUBSURFACE CONDITIONS Artificial Fill (Oaf): Medium to dark brown, damp, loose, CLAYEY GRAVEL (GC), with sand. Subsoil: Light to mediuin reddish-brown, moist, medium stiff, SANDY CLAY (CL). Santiago Peak Volcanics (Klsp): Medium reddish-brown and light gray, moist, medium dense to dense, SIL TY SAND (SM), with gravel. Highly weathered from 5 to 7 feet. At 7 feet becomes dense. Logged by: Project Manager: Depth to Water: Drive Weight: LES SAMP -~ z 0 -0 ~ ~ ~ g ~ ....:l ~ ::J IJJ p.. ~ ~] ~ ze. < ~ U'J p.. CK CK CK TSW CHC N/A N/A 'o' ~ ~ --.,J ~ ~Q ::J z u ~ ::J _£:, >-4 ~ 0 ~ 0 6.8 99.6 31.0 94.9 ~ 0 U'J ~ ~ 0~ j ss El MD, DS 9..,_......., _______________________ ,1,--,.iW.11~-'"--J.---I---I Test trench terminated at 9 feet. 10 !At (::1-IR.ISTIAN WHEELER. L:NGINFLRING BY: JOB NO.: PROPOSED SINGLE-FAMILY RESIDENCE El Fuerte Street, Lot 71, Carlsbad, California HF DATE: September 2005 2050527 PLATE NO.: 2 ( . l i ' I l . • 3 i l -LOG OF TEST TRENCH NUMBER T-2 Date Excavated: Equipment:· Existing Elevation: Finish Elevation: () 'Z' 0 ~ r-l 7/5/2005 Case 580L Backhoe ......., u ~ l: SUlvfMARY OF SUBSURFACE CONDITIONS s ~ Logged by: Project Manager: Depth to W~ter: Drive Weight: SAMPLES l:il z ~ 0-.:;-- ~ ~ 0 ~1 tS 0 ~ i:Q l:il ..Q Z6 <: l:il CJ) p... TSW CHC N/A N/A 'c' ~ ~ -;;;::. ......., ~ t: Q 0 C/) ~t; ::J z u t3 o.E:; 0~ >-t ~ j 0 ~ 0 " ~k:,; · T"l"'oili Medium brown, d,mp, loose, SIT.TY SAND (SM), -1-------------------------------------+-------- -2 -3 I- -4 -5 - I-6 - -7 I- -8 -9 - '--10 Subsoil: Medium to dark reddish-brown, damp to moist, medium stiff, SANDY CLAY (CL). Sedimentary ~ock Associated w / s·antiago Peak Volcanics (Kf sp): Light to medium gray and medium reddish-brown, moist, medium dense, CLAYEY SAND (SQ. Hard rock floaters up to 36" in diameter from 3½ to 7 feet. Medium reddish-brown, moist, dense to very den~e, SILTY SAND (S:r-.D, fine to medium-grained. Test trench terminated at 10 feet. CK CK 27.3 87.2 CK !N PROPOSED SINGLE-FAMILY RESIDENCE El Fuerte Street, Lot 71, Carlsbad, California CHR..ISllAN WHEELER.. l."NGINJ:l:RING BY: JOB NO.: ·\ HF DATE: September 2005 2050527 PLATE NO.: 3 l r I i i . I i ; t i . - LOG OF TEST TRENCH NUMBER T-3 Date Excavated: 7/5/2005 Equipment: Case 580L Backhoe Existing ;Elevation: Finish Elevation: 2 3 4 5 6 7 8 SUMMARY OF SUBSURFACE CONDITIONS Topsoil: Medium to dark brown, damp, loose, SILTY SAND (SM). Subsoil: Medium to dark reddish-brown, damp to moist, medium stiff, SANDY CLAY (CL). Sedimentacy Rock Associated w / Santiago Peak Volcanics (Kf sp): Medjum-rcddish-brown to medium gt_ay, damp to moist, medium dense to dense, CLAYEY SAND (SC), fine to medium-grained. Medium reddish-brown to light gray, damp to moist, dense, SILTY SAND (SM), fine to medium-grained. Logged by: Project Manager: Depth to Water: Drive Weight: SAMPLES U.l z ~ 0---. ~ ff ;:j ....:i :::, ~ ~ i:Q ~ .Q ~ Z6 -< ~ Cl) p.. CK CK CK TSW CHC NIA NIA ,-.. ~ ~ ~ ~ ~ tQ ~ Cl) :::, z u ~~ t-1 ::::,6 0~ (/) ..... ~ j 0 ~ Q 17.8 101.5 5.7 138.4 9 l-"'--,-------------------------+---+---1---+----J----+-~ 10 Test trench terminated at 9 feet. w CHR.ISllAN WHEELER J:NGINI:ERING BY: JOB NO.: J.>RO~OSED SINGLE-FAMILY RESIDENCE El Fuerte Street, Lot 71, Carlsbad, California_ HF DATE: September 2005 2050527 PLATE NO.: 4 -e .e LABORATORY TEST RESULT~ PROPOSED SINGLE-FAMILY RESIDENCE ELFUERTE STREET, LOT 71 CARLSBAD, CALIFORNIA MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557) Sample Location Sample Pescl'iption Maximum Density Optimum Moisture Treu.ch T-1@ 5'-9' Reddish-brown, SM 119.2 pcf 11.8 % DIRECT SHEAR (ASTM D3080) Sample Location Sample Type Friction • -\ogle Cohesion Trench T-1 @5'-9' Remolded to 90 % 31 ~ 300 psf EXP ANSI ON INDEX (ASTM D4829) Sample Location Initial Moisture I~1itial Dry Density Final Moisture E.\'.pansion Index Trench T-1@3½'-5' .14.6% 98.7 pcf 32.6% 120 (very high) SOLUBLE SULFATES (CALIFORNIA TEST 417) Sample Location Soluble Sulfate C\VE 2050527.03 Trench T-1 @ 0-3½' 0.003 % (S04) . September 2005 Plate No. 5 f ' I ' I ' l -1 % Slope Minimum . H J,l I.Yl--. . ~ [ 6-inch Minimum 6-inch t Max. r:_==::::..:J 3 / 4 inch Crushed Rock or Mirafi GlOON or Equivalent Geofabric Completely Wrapped Aroun'd Rock Minimum 4:in~h Diameter Perforated Pip~ PVC Schedule 40 . '-I 'I-.., . : ~~-. : . ;:,, ··• '.'Y ·._.,'-I .. 9 ·'-I.·~ ;: ~-v , .. -· I21' . . . ~ . .; ).', .,: ·. I ..,. 10·· .. 'f . r . . t/.Y/Y Waterproof Back of Wall Per Architect's Specifications Top of Ground +----...:.--/_orC-oncrete-Slab _l. . / /Y'f...l'y. /.Y HY,.; L 6-inch Minimum RETAINING WALL SUBDRAIN DETAIL '!N CHRISTIAN· WHEELER r:--;c1Nf1'.Rl~G 4925 1\11 ;RCL'RY STREET SAN Dll:(;~). C'.ALJFORNIA 92111 TEI. (858) 496-9760 FAX. (858) 469-9758 No Scale BY: PROPOSED SINGLE-FAMILY RESIDENCE El Fuerte Street, Lot 71, Carlsbad, California D,\TE: September 2005 JOB NO.: 2050527.03 PL:\TENO.: 6 (. f \ I ,_ l L ' f . i 1 ' I -CWE 2050527.03 Septembe; 2005 REFERENCES -Appendix A,-Page A-1 Anderson, J .G .; Rockwell, R.K. and Agnew, D.C., 1989, Past and Possible Future Earthquakes of Significance to the San Diego Region, Earthquake Spectra, Volume 5, No. 2, 1989. I ' Blake, T. F., 2000, Documentation for Eqfault Version 3.0, TI101_11as F. Blake Computer Services and · Software. Boore, David M.,Joyner, William B., and Fumal, Thomas E., 1997, "Empirical Near-Source Attenuation Relationships for Horizontal and Verticai Components of Peak Ground Acceleration, Peak Ground Velocity, _and Pseudo-Absolute Acceleration Response Spectra", in Seismologi~al Research Letters, Volume 68, Number 1,January/February 1997. Countywide Flood Insurance Rate Maps, Panels 1032F and 1051F, prepared by the Federal Emergency Management Agency, effective date June 19, 1997. Hart, E.W., 1994, Fault-Rupture Hazard Zones in California, California Division of1"1ines and Geology Special Publication 42. Jennings, C.W., 1975, Fault Map of California, California Division of Mines and Geology, Map No. 1, Scale 1:750,000. Kern, P~, 1989, Earthquak_es and Faults"in San Diego County, Pickle Press, 73 pp. \Vesnousky, S.G., 1986; "Earthquakes, Quaternary Faults, and Seismic Hazards in California", in Journal of Geophysical Research, Volume 91, No. B12, pp 12,587 to 12,631, November 1986. ' : -CWE 2050527.03 September 2005 .e. Appendix B, Page B-1 RECOMMENDED GR.1\DING SPECIFICATIONS -GENERAL PROVISIONS GENERAL INTENT PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 71 CARLSBAD, CALIFORNIA The intent of these specifications is to establish procedures for clearing, compacting natural ground, preparing areas to be filled, and plac~g and compacting.fill soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary geotechnical investigation report and/ or _the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede the provisions containt;d hereina.fter in the case of conflict. These specifications shall only be used in conjunction with the geotechnical report for which they are a part. No deviation from these specifications will be allowed, except where specified in the geotechnical report or in other written communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian \'(.'heeler Engineering shall be reta11,1ed as the Geotechnical Engineer to obserYe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer or his representatiYe provide adequate observation so that he may provide his opinion as to whether or not the work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geo technical Engineer and to keep him appraised of work schedules, changes and new information and data so that he may provide these-opinions. In the event that any unusual conditions not covered by the special provisions or preliminary geotechnical report are encountered during the grading operations, the Geotechnical Engineer shall be contacted for further recommendations. If, in the opinion of the Geotechnical Engineer, substandar~ conditions are encountered, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc., construction should be stopped until the ~onditions are remedied or corrected or he shall recommend rejection of this work. Tests used to determine the degree of compaction should be performed in accordance with the following American Society for Testing and Materials te.st methods: l l·'. /'' ! I -C\'{1:E 2050527.03 September 2005 Maximum Density & Optimum Moisture Content -ASTM b-1557-91 Density of Soil In-Place -ASTM D-1556-90 or ASTM D-2922 Appendix B, Page B-2 All densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM testing procedures .. PREPARATION OF AREAS TO RECEIVE FILL All vegetation, brush and debris derived from clearing operat;ions shall be removed, and legally disposed of . . All areas disturbed by site grading should be left in a neat and finished appearance, free from unsightly debris. After clearing or benching the natural gro1:1nd, the areas to be filled shall be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soil which possesses an in-situ density of at least 90 percent of its maximum dry density. . . \'Xlhen the slope of the natural ground receiving fill exceec;ls 20 percent (5 horizontal units to 1 vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent formational soil. TI1e lower bench shall be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to recei\'.'ing fill as specified herein for compacted natural ground Ground slopes flatter than 20 percent shall be benched when considered necessary by the Geotechnical Engineer. Any abandone_d buried ·structures encountered during grading operations must be totally removed. All underground utilities to be abandoQed beneath any proposed structure should be removed from within 10 feet of the structure and properly capped off. The resulting depressions from the above described procedure should be backfilled with acceptable soil that is compacted to the requirements of the Geotechnical Engineer. This includes, but is riot limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drains and water lines. Any buried ~tructures or utilities no.t fo be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recommendation will be n_ecessary. All w~ter wells which will be abandoned sl~ould be backfiJJc:;c;l and c:tpped in accordance to the requirements set forth by the Geotechnical Engineer. The top of the cap should be at least 4 feet below finish grade or 3 .! , .. -· C\VE 2050527 ._03 September 2005 Appendix B, Page B-3 feet below the bottom of footing whichever is greater. The type of cap -will depend on the diameter of the well and should be determined by the Geotechnical Engineer and/ or a qualified Structural Engineer. FILL MATERI.Al.. Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized rocks and expansive or detrimental soils are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation, or soils with low strength characteristics may be thoroughly mixed with other soils -~o provide satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any·unport material shall be approved by the Geotechnical Engineer before being brought to the site. PLACING AND COMPACTION OF FILL Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compaction effort ~o b~ efficiently applied to achieve the specifie_d degree of compaction. Each layer shall be uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to economically com~act the layer. Co~paction equipment should either be specifically designed for soil compaction or of proven reliability. Th~ minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminary geotechnical investigation report .. 'w11en the structural fill material includes rocks, no rocks -will oe allowed to nest and all voids must be . carefully filled with soil such that the minimum degree of compaction recommended in the Special Prov.1sions is achieved. The maximum size and spacing of rock permitted in structural fills and in non- structural fills is discussed in the geotechnical report, when applicable. Field observati~n and compaction tests to e~timate the degree of compaction of the fill will be taken by the Geotechnical Engineer or his representati~e. The location and frequency of the tests shall be at the Gcotcchnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than the required degree of compaction, the layer shall be rewQ~k~d to the satisfaction of the Geotechnical . "' Engineer and until the desired relative compaction has been obtained. ' ' ) ' I , i ' -CWE 2050527.03 September 2005 Appendix B, Page B-4 Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot r~ller shall be at vertical intervals of not greater than four feet. In addition, fill slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut- . back to ·finish contours after the slope has been constructed. Slope compaction operations shall result in all fill material six or more inches inward_ from the finished face of the slope having a relative compaction of at least 90 percent of inaximum dry density or the degree of compaction specified in_ the Special Provisions section of this specification. The cqmpaction operation on the slopes shall be continued until the Geote~hnical-Engineer is of the opinion that the slopes will be surficially stable. Density tests in the slopes will be made by the Geotechnical Engineer during construction of the slopes to determine if the required compaction is.being achieved. Where failing tests occur or other field problems arise, the Contractor will be notified that day of such conditions by written communication from the Geotechnical Engineer or his representative in the form of a daily field report. If the method of achieving the required slope compaction selected by the Contractor fails to produce the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction is obtained, at no cost to the Owner or Geotechnical Engineer. CUT SLOPES The Engineering Geologist shall inspect cut slopes· excavated in rock or lithified formational material during the grading operations at intervals determined at his discretion. If any conditions not anticipated in the preliminary report such as perc~ed water, seepage, lenticular or confined strata of a potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shall be analyzed by the Engineering Geologist and Geotechnical Engineer to determin~ if mitigating measures are necessary. Unless otherwise specified in the geotechnical report, no cut slopes sh~ll be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Geotechn.ical Engineer or his r~pr~~entative shall be made during the filling and compaction operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or his representative or ·'--C\'(IE 2050527.03 September 2005 -Appendix B, Page B-5 the observation and t_esting shall release the Grading Contractor from his duty to compact all fill material to the specified degree of compaction. SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. RECOMMENDEJ) GRADING SPECIFICATIONS -SPECIAL PROVISIONS RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natural ground, compacted fill, and compacted backfill shall be at least 90 percent. For street and parking lot subgrade, the upper six inches should be compacted to at least 95 percent relative compaction. EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion index of 50 or greater when tested in accordance with the Uniform Building Code Standard 29-2. OVERSIZED MATERIAL: O,rersized fill material is generally defined herein as rocks or lumps of soil_ over 6 iQ.ches in diameter. Oversized materials should not be placed in fill unless recommendations 9f placement of such material is-provided by the Geotechnical Engineer. At least 40 percent of the fill soils shall pass through a No. 4 U.S. Standard Sieve. TRANSI.TION LOTS: \Vhere transitions between cut and fill occur within the proposed building pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and . . recompacted as structural backfill. In. certain cases that would be addressed in the geotechnical report, special footing reinforcement or a combination of special footing reinforcement and undercutting may be required.