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Home My WebLink AboutPD 06-01; BAIHAGHY RESIDENCE; REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION; 2005-09-21I I I I I I I I I I I I I I I I I I I w CHRJSTIAN WHEELER. ENGINEER.ING REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 69 CARLSBAD, CALIFORNIA PREPARED FOR: TONY BAIHAGHY 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 fJ) Ok-D) I I I I I I I I I I I I I I I I I I CHR..ISTIAN WHEELER.. ENGINEER.ING September 21,2005 Tony Baihaghy C\V'E 2050527.01 Post Office Box 131446 Carlsbad, California 92013 SUBJECT: REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION, PROPOSED SINGLE-FAMILY RESIDENCE, LOT 69, EL FUERTE STREET, CARLSBAD, CALIFORNIA. Dear lvrr. Baihaghy: In accordance with your request, we have completed a preliminary geotechnical investigation for the single- family residence proposed at the subject property. We are presenting herein our fmdings and recommendations. In general, we found the subject property suitable for the proposed development, pro\Tided the recommendations presented herein are followed. Based on our investigation, we have concluded the following: • The site is ultimately underlain by dense to very dense metavolcanic rock and associated sedimentary rock, but is mantled by a two-to three-foot-thick layer of relatively loose surficial soils that 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 overexcavated in the areas to support fill and/ or settlement-sensitive improvements and be replaced as properly compacted fill. • The site is capped with moderately expansive clayey subsoil. This material will need to be mixed with the sandy portions of tlle on-site soils to create a non detrimentally expansive mix prior to being placed as structural fill, or be placed only in landscape areas where no concrete flat work will be constructed. I 4925 Mercury Street .. San Diego, CA 92111 .. 858-496-9760 .. FAX 858-496-9758 I I I I I I I I I I I I I I I I C\V'E 2050527.01 September 21, 2005 Page No. 2 • Based on the proposed grading plan, the building pad will consist of cut are~s and fill areas, with fills of valTing thickness. Additionally, we anticipate that although the metavolcanic rock and associated sedimentary rock mate~ial can be excavated to the proposed depths using heavy grading equipment, it will be difficult to excavate for foundations and/or utilities in tilis material using lighn.veight trenching equipment. Based on these conditions, it is recommended to undercut tile cut portions of the proposed pads dUl"ing grading to mitigate the potential for differential settiement and so that it will be possible to use normal trenching equipment during tile construction of the home. • The 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 affe~t the site is ground shaking due to seismic activity along one of the regional active faults. However, construction in accordance with the requirements of the Unifonn Building Code and other governmental regulations should provide a level of life-safety suitable for tile type of development proposed. 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, CHRISTIAN \'CHEELER ENGINEERIN G Charles H. Christian, RGE #00215 Curtis R. Burdett, CEG #1090 I CHC:CRB:scc cc: (6) Submitted I I I I I I I I I I I I I I I I I I I 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 ........................................................................................................................................... 5 Landslide Potential and Slope Stability ..................................................................................................... 6 Liquefaction .................................................................................................................................................. 6 Flooding ............................................................................................................................................... : ......... 6 TsunalIlls ................................................................................... : ................................................................... 7 Seiches ............................................................................................................................................................ 7 Conclusions ........................................................................................................................................................... 7 Recomluendations ................................................................................................................................................ 8 Grading and Eartlnvork .................................................................................................................................. 8 General.. ......................................................................................................................................................... 8 Observation of Grading .............................................................................................................................. 8 Clearing and Grubbing ........................................................................................................ : ....................... 8 Site Preparation ............................................................................................................................................ 8 Pad Undercuts ...................................................... : ..................................................................................... :.9 Processing of Fill Areas ................................................................................................................................ 9 COlupaction and Method of Filling ......................................... : ..... : ................................................... · ........ 9 Fill Slope Construction ..................................................................................................................... , ......... 9 Disposal of Oversize Rock ....................................................................................................................... 10 Iluported Filll\Iaterial ............................................................................................................................... 10 Teluporary Slopes .................................................................................................... , ................................. 10 Surface Drainage ........................................................................................ : ............................................... 11 Grading Plan Revie\v ................................................................................................................................. 11 Foundations ........................................................................................................ : ........................................... 11 General. ........................................................................................................................................ , ................ 11 Expansive Characteristics ......................................................................................................................... 11 Footing Dituensions .................................................................................................................................. 11 Bearing Capacity ............................................................................................................. : ............. : ........ : .... 11 Footing Reinforcing ............................................................................... : ................................................... 11 Lateral Load Resistance ............................................................................................................................. 12 Settleluent Characteristics ............................................................................................. : ........................ : .. 12 Foundation Plan Review ........................................................................................................................... 12 Foundation Excavation Observatiop., ............................................................................... : .................... 12 Seismic Design Parameters ........................................................................................................................... 12 On-Grade Slabs .............................................................................................................................................. 13 General. ........................................................................................................................................................ 13 CWE 2050527.01 Proposed Single-Family Residence Lot 69, EI Fuerte Street, Carlsbad, California I I I I I I I I I I I I I I I I I I I Interior Floor Slabs .................................................................................................................................... 13 I\1oisture Protection for Interior Slabs ................................................................................................... 13 Exterior Concrete Flatwork. .......................................................................................................•............. 14 Earth Retaining \Valls ................................................................................................................•................... 14 Foundations ............................................................................................................................................. , .. 14 Passive Pressure .......................................................................................................................................... 14 . Active Pressure ........................................................................................................................................... 14 \X1aterproofing and Subdrain ....................................................................................... : ............................ 15 Backfill ......................................................................................................................................................... 15 Soluble Sulfates ................................................................................................................................................ 15 Limitations ........................................................................................................... : ............................................... 15 Revie\v, Observation and Testing ................................................................................................................ 15 Uniformity of Conditions ............................................................................................................................. 16 Change in Scope ............................................................................................................................................. 16 Time Limitations ............................................................................................................................................ 16 Professional Standard .................................................................................................................................... 16 Client's Responsibility .................................................................................................................................... 17 Field Explorations .............................................................................................................................................. 17 Laboratory Testing ........................................................................... ; .................. : ....................... ; ... : .................. 17 CWE 2050527.01 Proposed Single-Family Residence Lot 69, El Fuerte Street, Carlsbad, California I I I I I I I I I I I I I I I I I I 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 6 Seismic Design Parameters, Page 13 Site Vicinity Map, Follows Page 1 Site Plan & Geotechnical Map Test Trench Logs Laboratory Test Results Retaining Wall Sub drain Detail References Recommended Grading Specifications-General Provisions C\VE 2050527.01 Proposed Single-Family Residence Lot 69, El F'uerte Street, Carlsbad, California I I I I I I I I I I I I I I I I I I w CHRISTIAN WHEELER ENGINEER.ING PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 69 APN 215-492-09 CARLSBAD, CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of a preliminary geotechnical investigation performed for a proposed single- family residence to be constructed on a vacant lot northwest 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. \\'e understand that a single-family custom home will be constructed on the lot. The main portion of the home will be one story, but a lower level garage will be tucked under the southwestern portion of the home and a second story will be constructed over the western portion. \V'e expect that the structure will consist of masonry construction for the below-grade portions and wood-frame construction for the above-grade portions. \'{.'e also expect that the residence \vill have on-grade concrete floor slabs and will be supported by conventional shallow foundations. Additional improvements will include a driveway that extends to the garage from El Fuerte Street and three level pads that step down in the rear yard area from the main level of the residence. Grading for the proposed home is expected to consist of cuts and fills of about ten feet and five feet, respectively, from existing grades. Grading for the remaining portions of the project is expected to consist of cuts and ftlls of about six feet and five feet, respectively, from existing grades and will include cut and fill slopes up to about ten feet in height. Building and site retaining walls up to about eight feet high are also snticipated. In order to augment our understanding of the proposed site development, our firm was provided with a preliminary grading 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. I 4925 Mercury Street + San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 I 1 I I I I I I I I I I I' I I I 1 I I North C\\IE 2050527.01 SITE VICINITY MAP (Adapted from Thomas Brothers Maps) PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET LOT 69 CARLSBAD, CALIFORNIA SITE September 2005 Figure 1 -------~-------' I I I I I I I I I I· I I I I I I I I I ,. C\\lE 2050527.01 September 21, 2005 . Page No. 2 This repordlas been prepared for the exclusive use of Mr. Tony Baihaghy, and his design consultants, for. specific application to dle project described herein. Should the project be modified, the conclusions and recommendations presented in this report should be reviewed by Christian \Vheeler 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 odler 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 laboratOl"Y data, and review o( relevant geologic literature. Our scope of service did not include assessment of hazardous substance contamination, recommendations to prevent floor slab moisture intrusion or the fo~mation 'of mold "rithin the structure, or any odler senrices not specifically described in the scope of senrices pres~nted below. IvIore specifically, the intent of our proposed investigation is to: a) b) c) d) e) Explore the subsurface conditions of the site to the depdls influenced by the proposed cons truction; Evaluate, by laboratory tests, the engineering properties of the various strata that may influence the proposed development, including bearing capacities, expan'sive characteristics and settlement potential; Describe tlle general geology at the site including possible geologic hazards that could have an effect on the site development, and provide the seismic design parameters as required by the most recent edition of the Uniform Building Code; Address potential construction difficulties that may be encountered due to soil conditions, groundwater or geologic hazards, and provide recommendations concerning dles'e problems; Deyelop soil engineering criteria for site preparation and grading, apd address the stability of proposed cut and fill slopes; I I I I I I I I I I I I I I I I I I , . CW/E 2050527.01 September 21,2005 Page No. 3 f) g) h) Provide design parameters for unrestrained and restrained retaining walls; Recommend an appropriate foundation 'system for the type of structures anticipated and deYelop soil engineering design criteria for the recommended foundation design; 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 d1e scope of our services, it should be understood Christian \X'heeler Engineering does not practice corrosion engineering. If such an analysis is considered necessary, we recommend that the client retain an engineering ftrm that specializes in this fteld 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 ,racant, rectangular parcel of land located on the northwestern side of El Fuerte Street, in the La Costa area of the city of Carlsbad, California. The lot is identified by Ass~ssor's Parcel Number 215- 492-09 and, in addition to being bordered by El Fuerte Street to the southeast, is bordered to the south and west by developed residential properties and to the north by a another vacant lot. Topographically, the lot generally slopes. gently to moderately towards the south with relatively low (± 5 feet), locally steeper cut slopes along EI Fuerte Street and along the southern property line, adjacent to an existing driveway for the neighboring properties to the south and west. The on-site elevations range from a low of approximately 211 feet neat; the southern property line to a high of approximately 234 feet near the northern property line. In terms of vegetation, the site is covered by mostly by low-lying weeds with a small amount of b~sh 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 Physiographi'c Province and the Coastal Plains Physiographic Province of San Diego County. Based on the results of our subsurface explorations and analysis of readily available, pertinent geologi<;. I I I I I I I I I I I I I I I I I I I C\,{,'E 2050527.01 September 21, 2005 Page No. 4 literature, the site was detennined to be underlain by a relatively thin layer of fill and/ or residual soils overlyins Jurassic/Cretaceous-age metavcolcanic rock minor amounts of associated sedimentary rock. These materials are described below: ARTIFICIAL FILL (Qaf): An approximately two-foot-thick layer of fill material was encountered within our exploratory trench T-2, which was excavated in the southern portion of the site. Due to its relatively thin nature, such material has not been mapped on the Site Plan and Geotechnical Map, included as Plate No.1 of this report. The fill material consisted of medium brown, silty gravel (GM) that was damp and loose to medium dense in consistency. Based on our experience with . similar soil types, we expect that the existing fill has a "low" expansion potentia~ low to moderate strength parameters, and low to moderate settlement potential. The existing fill is typically variable in consistency and is tllerefore considered unsuitable to support new fill and/or settlement-sensitive improvements. Tlus material, however, may be incorporated into structural fills provided it is free of organic debris. RESIDUAL SOIL: An approximately one-to two-foot-tluck layer of residual soil \~as encountered within each of our exploratory trenches. Due to their relatively thin nature, such materials have not been mapped on the Site Plan and Geotechnical Map, included as Plate No.1 of this report. The residual soils typically consisted of an approximately one-foot-thick layer of medium brown, damp, loose, silty sand (SJ\.1) topsoil over an approximately one-foot-thick layer of medium reddish-brown, moist, medium stiff, sandy clay (eL) subsoil; however, topsoil was not encountered with trench T-2. Based on our laboratory testing and experience with similar soil types, we expect tllat the topsoil has a "low" e.."pansion potential wIllIe tlle subsoil has a "medium" to "lugh" e:-.:pansion potential. \'{1e also expect tllat both tlle 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 tllerefore considered unsuitable to support fill and/or settlement-sensitive improvements. These materials, however, may be incorporated into structural fills provided they are free of organic debris and the subsoils are nU."ed witll odler on-site sandy soils prior to being placed as fill. The expansive subsoils will need to be mixed Witll otller on-site soils to provide a nondetrimentally expansive soil nU."{ture (EI less tllan 50). SANTIAGO PEAK VOLCANICS (KJsp): Below the fill and residual soils, tlle site is ultimately underlain byJurassic/Cretaceous-age metavolcanic rock and minor amounts of associated secfunentary rock identified as dle Santiago Peak Volcanics. The sedimentary rock was noted to consist of medium reddish-brown and light gray, damp, dense to very dense, silty sand (SJ\.1) tllat was generally moderately- I I I' I I I I I I I I I I I I I I I C\\TE 2050527.01 September 21, 2005 Page No. 5 to well-cemented and was moderately fractured in some areas. The sedimentary rock has relathrely high strengd1 parameters and a low expansion potential in its natural and compac;ted states. The metavolcanic rock was noted to consist of medium reddish-brown and medium gray, damp,to moist, dense to very dense, silty gravel (GM), wid1 sand and cobble. The sedimentary rock has relatively high strength parameters and a low expansion potential in its natural and compacted states. The sedimentary material and d1e metavolcanic material are suitable ill d1eir present condition to support fill and/or settlement- sensitive improvements and may also be used as structural fill. 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 d1e soil an:d the anticipated usage of d1e 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 d1e subject site but it should be noted d1at much of Southern California, including d1e San Diego County area is characterized by a series of Quaternary-age fault zones which typically consist of several individual, en echelon faults d1at generally strike in a norilierly to northwesterly direction. Some of d1ese fault zones (and d1e individual faults wid1in d1e zones) are classified as active while od1ers are not currendy considered to be active, according to the criteria of d1e California Division of J.'vIines and Geology. Active fault zones are d10se which haye shown conclusive evidence of faulting during d1e Holocene Epoch (the most recent 11,000 years). .A review of a,oailable geologic maps indicates that the active Rose Canyon Fault Zone is located approximately 10% kilometers west of the subject site. Other active fault zones in the region that CQuid possibly affect the site include the Ne\\rport Inglewood and Coronado Bank Fault Zones to the west and southwest, respectively, and the Earthquake Valley, Elsinore and.San Jacinto 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 I CW/E 2050527.01 September 21, 2005 Page No. 6 I· affect the site, based on our Deterministic Seismic Hazard Analysis (DSHA), are sU!TI1Uarized in the following Table!. I I. I I I I . 1 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 N ewport-Inglewood 18km 6.9 magnitude' 0.17'g Coronado Bank 3Skm 7.4 magnitude 0.14g Elsinore -Julian 38km 7.1 magnitude 0.11 g Earthquake Valley 63km 6.5 magnitude' .O.06g San Jacinto (Anza) 7Skm 7.2 magnitude 0.07 g Probable ground shaking levels at the site could range from slight to moderate, depending on such Iactdrs 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 improv'ements . LANDSLIDE POTENTIAL AND SLOPE STABILITY: As part of this investigation we revie\ved the I publication, "Landslide Hazards in the'Southern Part of the San Diego Metropolitan Area" by' Tan, 1995. I I I I I I I I I This reference is a comprehensive study that classifies San Diego County into areas of relative landslide susceptibility. 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 stability limits due to steep slopes and can be expected to fail locally when adversely modifi"ed. Sites 'within this classification are located outside the boundaries of known landslides but may contain obselyably unstable slopes that may be underlain by weak materials and/or adverse geologic structure. HO\ve'lier, 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 potential for landsliding at the subject site is low. LIQUEFACTION: The 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: As delineated on the referenced Flood Insurance Rate Maps prepared by the Federal Emergency Management Agency (10SlF), the site is located outside of the boundaries of both the 100-year . and SOO-year flood zones. I I I I I I < C\,{TE 2050527.01 September 21, 2005 Page No. 7 TSUNAMIS: Tsunamis are great sea waves produced by submarine earthquakes or volcanic etuptions. TIle site is not subject to risk from tsunamis. SEICHES; Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or reservoirs. 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 I recommendations presented herein are followed. The following are tlle most significant geotechnical conditions to adversely affect the proposed construction: I I I I I I I I I I • Our investigation 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 a two-to three-foot-tllick layer of relatively loose surficial soils that are considered unsuitabJe in their present condition ~o support fill and/or settlement-sensitive improvements. As such, any surficial soil that is not removed by the planned grading will need to be overexcavated in the areas to support fill and/or settlement-sensitive improvements and be replaced as properly compacted fill. • The site is capped witll moderately expansive clayey subsoil. This material will need to be mixed with the sandy portions of the on-site soils to create a non detrimentally expansive mix prior to being placed as .structural fill, or be placed only in landscape areas where no concrete flat work will be constructed. • Based on the proposed grading plan, the building pad will be underlain by cut areas and fill areas, with fills of ,oarying thickness. Additionally, we anticipate that although the metavcolcanic rock with minor amounts of associated sedimentary rock can be excavated to the proposed depths using heavy grading equipment, it will be very difficult to excavate for foundations and/or utilities in this material using lightweight trenching equipment. Based on these conditions, it will be necessary to underGut the cut portions of the proposed pads dl1ring grading to mitigate the potential for differential settlement and so that it will be possible to use normal trenching equipment during the consttucti~n of the home. I I I I I I I I I I I I I I I I I I CWE 2050527.01 September 21, 2005 Page No.8 The 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 significant geologic hazard that could affect the site is ground shaking due to seismic activity along one of the regional active faults. However, construction in accordance with the 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 th'e Uniform Building Code, the minimum requirements of City of Carlsbad, and the recommended Grading Specifications and Special Provisions attached hereto, except where specifically superseded in the text of tlus rc;port. Prior 'to grading, a representative of Christian \\1heeler Engineering should be present at the pre-construction fueeting to provide additional grading guidelines, if necessary, and to review the eartl1\vork schedule. 'OBSERVATiON OF GRADING: Continuous obselyation by the Geotechnical Consultant is essential <during th.e grading operation to confirm conditions anticipated by our investigation, to allow adjustments in design criteria to reflect actual field conditions exposed, and to deteruUne that the grading proceeds in general accordance with the recommendations contained herein. CLEARING AND GRUBBING: Site grading 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 tlle clearing and grubbing should be disposed of off-site. SITE PREPARATION: After clearing and grubbing, tlle site preparation will generally consist of tl~e , removal of unsuitable-surficial soils that are not removed by the planned grading and, where necessary to achieve the planned 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 two to three feet below the existing grades, but may be deeper in localiied 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 expansive subsoil should be uUxed witll I I I I I' I I I I I I I I I I I I I CWE 2050527.01 September 21, 2005 , Page No.9 the on-site sandy soils to produce a soil mixture with an Expansion Index of less than 50. The areas cleaned out of unsuitable soils should be approved by the geotechnical engineer prior to replacing any of the excavated soils. PAD UNDERCUTS: Based on the proposed grading, the residence will be supported partially by cut and partially by flIl. Additionally, we anticipate that very dense sedimentaty rock will be exposed in the cut pattions of the building pad, particularly the garage 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 inclination of at least two percent towatds the south in such a manner that water does not become trapped in the overexcavated zone. The overexcavated material should be replaced as structural fill, compacted to at least 90 % of maximum dry density. PROCESSING OF FILL AREAS: Prior to placing any new fill soils at constl"Ucting any new improvements in areas that have been cleaned out to teceive fill, the exposed soils should be scatified toa depth of 6 inches, moistute conditioned, and compacted to at least 90 percent relative compaction. ,COMPACTION AND METHOD OF FILLING: Structutal fill should be compacted to a telative compaction of at least 90 percent of maximum dry density as determined by ASTM Labotatory Test D1557- 91. Fills should be 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 eartll material, free of trash or debris, roots, vegetation, or other materials detetmined to be unsuitable by our soil technicians orproj~ct geologist. Fill material should be free of rocks or lumps of soil in excess of twelve inches in maximum dimension. However, in the upper two feet of subgrade, no rocks or lumps of soil in excess of six 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. Utility trench backfill within five feet of the proposed 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 tllat fill slopes required for the site will be less than 15 feet in height. All fill slopes should be constructed at an inclination of 2:1 or flatter Qlorizontal to vertical). Compaction of slopes should be performed by back-rolling witlla sheepsfoot compactor at vertical intervals of four feet or less as tlle fill is being placed, and track-wa:lking tlle I I I I I I I I I I I ,I I I I I I I C\V'E 2050527.01 September 21, 2005 Page No. 10 face of the slope when the slope is completed. As an alternative, the fill slopes may be overfilled brat 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 inclination of 5:1 (horizontal to vertical). Keys should be constructed at the toe of all fill slopes. The keys should extend at least 12 inches into fJ..r1U 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. Based on the proposed grading it \vill be necessary to place oversized material in landscaped areas or to export the material from the site. 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 Geotechnical 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 of less than 50, less than 25 percent larger than the standard #4 sieve, and less than 25 :percent finer than the standard # 200 sieve. TEMPORARY SLOPES: We anticipate that temporary excavation slopes will be up to 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 sloped 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 conditions can be identified. Deep, temporary confined excavations, such as for underground utilities, should use sloping sides, shoring, or "trench boxes" during construction, or any odler approved 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 excavations as required to maintain the'stability of the excavation sides where the friable sands are exposed. The contractor's "responsible person", as defined in 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 depdl, exceed those specified in local, state, and federal safety regulations. I I I I I I I C\\TE 2050527.01 September 21, 2005 Page No. 11 SURFACE DRAINAGE: The ground around the proposed structure should be graded so dlat surface water flows rapidly away from the structure \vithout ponding. In general, we recommend that dle ground adjacent to the structure slope away at a gradient of at least two percent. Densely vegetated areas where !'Unoff can be impaired should have a minimum gradj.ent of at least five percent within the first. three feet from the st!'Ucture. Gutters and downspouts should discharge into controlled drainage devices. GRADING PLAN REVIEW: The fmal grading plans should be submitted to this office for review in order to ascertain that the recommendations of iliis report have been implemented, and dlat no additional recommendations are needed due to changes in the anticipated development plans. FOUNDATIONS GENERAL: Based on our findings and engineering judgments, ilie proposed structure may be supported by I conventional continuo~s and isolated spread footings. The follO\ving recommendations are considered the minimum based on soil conditions and are not intended to be lieu of structural considerations. All foundations I I I I I I I I I I I should be designed by a qualified structural engineer. .EXPANSIVE CHARACTERISTICS: Provided the recommendations presented in this report are follqwed, we anticipate that special foundation design for heaving soils will not be necessary. FOOTING DIMENSIONS: It is our opinion dlat dle proposed structure may be supported by conventional continuous and isolated spread footings. Spread footings should be embedded at least 18 inches below fmish pad grade for one-and two-story portions of dle residence. Continuous footings should have a m.iillinum widdl ' of 12 and 15 inches for one-and two-story portions of ilie residence, respectively. Isolated spread footings should have a minimum widdl of 24 inches. Retaining wall footings should have a mininmm embedmel;1t of 18 inches below the lowest adjacent grade and should have a minimum width of 24 inches. BEARING CAPACITY: Spread footings widl an embedment of 18 inches and a widdl.of 12 inches may be designed for an allowable soil bearing pressure of 2,500 pounds per square foot (ps0. TIus value may be increased by 800 psf for each additional foot of embedment depili and 250 psf for each additional foot of widili, up to a maximum of 4,000 psf. The bearing value may also be increased by one-third for combinations of temporary loads such as dlose due to \vind or seismic loads. FOOTING REINFORCING: Reinforcement requirements for foundations should be provided by a' stluctural engineer. However, based on dle expected soil conditions, we recommend that the minimum I' I I I I I, I I I I I I I I I I I I CWE 2050527.01 September 21, 2005 Page No. 12 reinforcing for continuous footings consist of at least two No.5 bars positioned dlree'inches above dle bottom of the footing and two No.5 bars positioned approximately two inches below dle top of the footing. LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction between me bottom of the footing and the supporting soil, and by me passive pressure against dle 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 equiYalent fluid weight of 350 pounds per cubic foot. These values are based on dle assumption dlat the footings are poured tight against undisturbed soil. If a combination of me passive pressure and friction is used, the friction value should be reduced by one-dlird. SETTLEMENT CHARACTERISTICS: The anticipated total and differential setdement is expected to be less than about one inch and one inch over forty feet, respectively, provided the recommendations presented in this report are followed. It should be recognized dlat 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 tlus office for review in order to ascertain dlat the recommendations of dlls report have been implemented, and tllat no additional ,recommendations are needed due to changes in dle anticipated construction. FOUNDATION EXCAVATION OBSERVATION: All footing e..'(cavations should be observed by Christian \\:'heeler Engineering prior to placing reinforcing steel to 'determine if the foundation recommendations presented herein are followed and that the foundation soils are as anticipated in the prepa~ation of dus report. All footing excavations should be excavated neat, level, and square. All loose <;>r unsuitable material should be removed prior to me 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 Acceleration at the site i~ estimated to be approximately 0.25 g. For structural 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 d~e location of the site greater than 10 kilometers from the Rose Canyon Fault Zone (Type B Fault), Near Source Factors No equal to 1.0 and N,. equal to 1.0 are also applicable. These values, along with other seisnucally I I I I I I I I I I I I I I I I I I I C\'{lE 2050527.01 September 21, 2005 Page No. 13 related design parameters from the Uniform Building Code (UBC) 1997 edition, 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 16-1 Seismic Zone Factor Z 0.40 16-1 Soil Pro me Type SC 16-Q Seismic Coefficient ea 0.40 Na 16-R Seismic Coefficient C-0.56 N,. 16-S Near Source Factor Na 1.0 16-T Near Source Factor N,. 1.0 16-U Seismic Source Type 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. ~NTERIOR fLOOR SLABS: For conventional slabs, the minimum slab thickness should be four inches (actual) and the slab should be reinforced \vith 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 extend into the perimeter footings at least SLX inches. The garage slab may be constructed independent' from the garage perimeter footings, but should have a felt strip between the slab and footing. If the garage slab and footings are constructed monolithically, the ,reinforcement should extend into the perimeter 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 anticipated. The purpose of the moisture/vapor retarder is to attempt to ininimize 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 wHI 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. I I I I I I I I I I' I I I I I I I I C\V'E 2050527.01 September 21, 2005 Page No. 14 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 concrete floor slabs. If sand is used, which is the most common subsiab 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 between the underlying soil and the conq:ete slab. In addition, a 15·mil polyethylene membrane, such as Stago-\X1rap, 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 recommendation and consideration of ACI 302, "Guide for Concrete Floor and Slab Construction" and ASTM E1643, "Standards Practice for Installation of\X1ater 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 tlle 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 mi." design recommendations to help minimize the concrete permeability. EXTERIOR CONCRETE FLATWORK: Exterior slabs should have a minimum thickness of fou~ inches. Reinforcement should be placed in exterior concrete flatwork to reduce the potential for tracking 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. 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 concrete to the on-site soil may be assumed to be 0.35 for the resistance to lateral . movement. \\'hen combining frictional and passive resistance, the friction should be reduced by one-third. The upper 12 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" efl.r~h retaining structures 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 I C\\·'E 2050527.01 September 21, 2005 Page No. 15 I cubic foot should be added to the above value for 2:1 (horizontal to vertical) sloping backfill. These pressures do not consider any other surcharge. If any are anticipated, this office should be contacted for the I I I I I I I I I I I I 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 sub drain detail is provided on the attached Plate Number 6. \Ve recommend that the Geotechnical Consultant observe all retaining wall 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 fol' 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 \vith California Test Method 417. The result of this test indicated that the representative soil sample had a soluble sulfate content of 0.018 percent. Soils with a soluble sulfate content ofless than 0.1 percent are considered to be negligible and no special recommendations are needed. LIMITATIONS REVIEW, OBSERVATION AND TESTING The recommendations presented in this report are contingent upon our review of final plans and specifications. Such plans and specifications should be made available to. the geotechnical engineer and engineering geologist so that they may review and verify their compliance with this report and with the Uniform Building Code. It is recommended that Christian \Vheeler Engineering be retained to provide continuous soil engi?eering 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 consqu~tion. I eWE 2050527.01 September 21, 2005 Page No. 16 I UNIFORMITY OF CONDITIONS I 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 I I I I 'I I I I' I I I I' I I- I exploration 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 thar.rpay be encountered during site development should be brought to the attention of the geotechnical engineer so dlat he rna)' 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 dle 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 i review by us verifying the suitability of dle conclusions and recommendations. PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession currendy practicing under similar conditions and in d1e same locality. The client recognizes that subsurface conditions may vary from those encountered at the locations where our borings, surveys, and explorations are ma.de, al1d that our data, interpretations, and recommendations be based solely on the information obtained by us. \Ve will be responsible for those data, interpretations, and recommendations, but shall not be responsible for the interpretations by others of the information developed. Our selvices consist of professional consultation and observation only, and no warranty of any \ I " I I ·1 I I I I I I I I I I· I CWE 2050527.01 September 21, 2005 Page No. 17 kind whatsoever, express 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 clle information and recommendations contained herein are brought to the attention of the structural engineer and architect for the project and incorporated 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 exploration's were made at dle 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 ge<;>logy 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 Classification System. In addition, a yerbal textural description, the wet color, the apparent moisture and the density or consistency are provided. The density of granular 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 st:1ff, stiff, very stiff, or hard. Disturbed and "relatively undisturbed" chunk samples of typical and representative soils were obtained and transported to our laboratory for testing. LABORATORY TESTING Laboratory tests were performed in accordance with dle generally accepted American Society for Testing and' J\.{aterials (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 ilie tests performed is presented below: I I I I I I I I I I I I I I I I C\'\JE 2050527.01 September 21, 2005' Page No. 18 a) b) c) CLASSIFICATION: Field classifications were verified in the laboratory by visual examination; The flnal soil classifications are in accordance with the Unified Soil Classification System. MOISTURE-DENSITY: In-place moisture contents and dry den.sities were determined for representative soil samples. This information was an aid tq 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. COMPACTION TEST: The maximum dry density and optimum moisture content of typical soils were determined in the laboratory in accordance with ASTM Standard Test D-15~7, Method A. The results of this test are presented on Plate' No.5. d) DIRECT 'SHEAR TEST: Direct shear tests were performed on representative samples of the on- site material to determine the failure envelope based on yield shear strengdl. The shear box was designed to accommodate a sample having a diameter of 2.375 inches or 2.50 inches lJ.nd 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 strain of approximately 0.05 inch per minute. The results of these tests are presented on Plate No.5. e) EXPANSION INDEX TEST: Expansion Index testing was performed on a remolded representative sample of the 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 then compacted ina 4-inch-diameter mold in two equallayel;s by means of a tamper, then trimmed to a final height of 1 inch, and brought to a saturation of approxinlately 50 percent. The specimen was placed in a consolidometer with porous stones at the top and bottom, a total normal load of 12.63 pounds was placed (144.7 psf), and the sample was' allowed to consolidate for a period of 10 minutes. The sample was saturated, and dle change in vertical movement was recorded until the rate of expansion became nominal. The expansion index is reported on Plate No.5 as the total vertical displacement times 1000. f) SOLUBLE SULFATES: The soluble sulfate content was determined for samples of soil likely to be present at dle foundation level. The soluble sulfate content was determined in accordance with California Test Medlod 417. The results are presented Plate No.5. I I 'I I I I I I I I I I I I I I I I I ." . ~ .. ~ .. ~. H' : T '. \ -SIo'~ o ,\ . '\~~ \\~ -----r=: x~~~-....... FFE 239 FFE 226 \\\~ .. t . \\! 1\,--> ,111, JE ~, : . " . '-'~" .. '-' -,-........ " LEGEND I IT -3 . AP~HOXIMATE TEST TRENCH LOCATION KJsp SANTIAGO PEAK VOLCANICS NOTE: SURFICIAL SOIL LAYER LESS THAN 2 FEET THICK~RE NOT MAPPED .~ 20' ,s' rD' S' p' 20' 40' GRAPHIC SCALE: '"=20' 4925 Mereu CHRISTIAN WHEELER ENG I N E'E R I N G PROPOSED SFR LOT 69 BY: CHC/SCC/HC .. DATE: ~9-14-05 JOB NO.:' 2050527.1 PLATE NO.: 1 ~i:- '-i .... '- I _ "'''-''-'~':::'':''\Do2"16'3. \ -1 -.-,---,,------"" \ l-20.23'. " -,,'-, "--,,-----,,--"-----"-----,, --"-. CONCRErDRII'CWAY. ~,R-470.75 \ .. ---I = I -"..!:::.:1 -I .-~~ -I- PAD 225' KJsp 228 CONCREr DRI'£WA Y FFE 254 \ lit:] \' .\~. I \ l-I a: I . :> ~II -i~ ~ lUJ ~I;"I .. . lllr.::: ;1~11KI • 0: <=, II. I / , I i Jf ~. a: /2 Iii! 'AS BUILT' RCE ___ EXP.____ DATE REV IE liED BY, INSPECTOR DATE . I SHEET I CITY OF CARLSBAD I SHEETS I I----li--~+--I -1-1 --+-1--+1-11 1 . ENGINEERING DEPARTMENT 4 . . • • • • • ·IGRADING PLANS FOR: 0000 EL FUERTE ST OWNER RESIDENCE 1 1 _I 1 1 -I 1 : II'TITLE SHEET ~,.--~-"-;;;;;=-=====9 OAlr; I INITIAL ENGINEER or WORK .&" DATE INITIAL DATE INInAl REVISION DESCRIPTION OUiER APPROVAL aTY APPROVAL MW/DD/Y'YYY EXPIRES PROJECT NO. PROJECT NO. 'I I 1 I 1 I I I 1- I I I I I I LOG OF TEST TRENCH NUMBER T-1 Date Excavated: Equipment: Existing Elevation:. Finish Elevation: 7/5/2005 Case 580L Backhoe SUMMARY OF SUBSURFACE CONDITIONS ...... oDs('I: l\'fedium brown, damp, loose, SILTY SAND (SM). I-1 Subsoil: Medium to dark reddish-brown, moist, medium stiff, SANDY CLAY (eL). Logged by: Project Manager: Depth to Water: Drive Weight: ISAMPLFS CK TSW CHC N/A , .N/A EI - 2 ~~~----------------------------------------------------~-+~*---4----r--~~--~ ..... : ...... :::: Sedimentary Rock Associated w I Santiago Peak Volcanics (KJsp): :MD, IvIedium reddish-brown and light gray, moist, medium dense to dense, CK 8.7 134.7 DS, SILTY SAND (51\1), fine to medium-grained. SS At 4 feet becomes dense, slightly to moderately cemented. CK 4.9 145.8 Tcst trench terminated at 9 feet. '-10 I.t-----------r--------------I I I I "~f ',... CHR.ISTIAN WHEELER. [NGIN[L-RINC BY: JOB NO.: PROPOSED SINGLE-FAMILY RESIDENCE EI Fuerte Street, Lot 69, Carlsba4,California HF DATE: September 2005 2050527 . PLATE NO.: 2 I I I I I I- I I I I I I I I I I I I I LOG OF TEST TRENCH NUMBER T-2 Date Excavated: 7/5/2005 Logged by: TSW Equipment: Case 580L Backhoe Project Manager: eHC Existing Elevation: Depth to Water: N/A Finish Elevation: Drive Weight: N/A SAMPLES .z-. c..? Z ~ 3 ~ '0' v §I ~ J::l ~ '-" U ~ ~ >-I ~ t1Q f-; ::c SUMI\:[ARY OF SUBSURFACE CONDITIONS ~ H ;:J Z u p.... 0... H ::J 4l f-! ;:J6 ~ ~ 0... ~ r/.) Q ::s Z H ~ c..? <: ~ 0 V) 0... ::s Q - Artificial Fill (QaO: Medium brown, damp, loose to medium dense, I-1 SILTY GRAVEL (Gl\1), with_sand. -2 Subsoil: Medium to dark reddish-brown, moist, medium stiff, I-3 SANDY CLAY (CL). CK r ::':-1:-Sedimenta~ Rock Associated w L Santiago Peak Volcanics (KJ:sp): .. :,,' .:. :::::'" 1 - 4 I Medium reddish-brown and medium gray, moist, dense to very dense, SILTY SAND (S}'1), fine to medium-grained, well cemented. CK 17.8 129.1 I-5 Practical refusal at 5 feet. i- 6 i-7 - 8 I-9 I ..... 10 - .• ~, 'I". PROPOSED SINGLE-FAMILY RESIDENCE El Fuerte Street, Lot 69, Carlsbad, California >; II ~ ~ CHR.ISTIAN WHEELER. BY: HF DATE: September 2005 ENGINL"J:RINC JOB NO.: 2050527 PLATE NO.: 3 I I I I I I I I I I I I I I I LOG OF TEST TRENCH NUMBER T-3 Date Excavated: 7/5/2005 Equipment: Case 580L Backhoe Existing Elevation: Finish Elevation: SUM1·1ARY OF SUBSURFACE CONDITIONS _, Topsoil: Medium brown, damp, loose, SILTY SAND (S:NI), with - 1 I "':~:~ili M,dium reddi,h-bwwn 'nd m,dium "",y. moi". m,dium I-2 stiff, SANDY CLAY (CL). Santiago Peak Volcanics (KJsp): Ivledium reddish-brown and medium gray, damp to moist, dense, SILTY GRA. VEL (Gl\1), with sand and cobble. At 3 feet becomes very dense with fractured rock. Logged by: TSW Project Manager: CHC Depth to Water: N/A Drive Weight: N/A iSAMPLE" / CK 11.5 114.8 ~31 I-4 ~~------------------------------------------------~--~-+---+---+----~~ Practical refusal at 4 feet. - 5 6 r-7 r-8 r-9 '-10 I~------~----------~~ I I I '~f fl'. CHRJSTIAN WHEELER. LNGINt:l'RINC BY: JOB NO. : PROPOSED SINGLE-FAMILY RESIDENCE EI Fuerte Street, Lot 69, Carlsbad, California HF DATE: September 2005 2050527 PLATE NO.: 4 I I I I I I I I I I I I ·1 I I I I I I LABORATORY TEST RESULTS PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET. LOT 69 CARLSBAD, CALIFORNIA MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557) Sample Location Sample Description :Maximum Density Optimum Moisture Trench T-1 @ 2'-7' Reddish-brown, SM 124.0 pef 12.0% DIRECT SHEAR (ASTM D3080) Sample Location Sample Type Friction Angle Cohesion Trench T-1 @ 2'-7' Remolded to 90 % 28 0 300 psf EXPANSION INDEX (ASTM D4829) Sample Location Initial Moisture .'initial Dry Density Finall\Ioisture Expansion Index Trench T-1 @ 112'_2' 13.0% 93.0 pcf 32.7 % 63 (medium) SOLUBLE SULFATES (CALIFORNIA TEST 417) Sample Location Soluble Sulfate C\X'E 2050527.01 Trench T-1 @ 2'-7' 0.Q18 % (S04) September 2005 Plate No.5 I I I I I I I I I I I I I I I I ______ ~---~===-~l'~~~S~lo~p~e~N.U7_·n~i~m~um=---._17~--- '/'I.../V X J.f /.Y I' ~ HI 6-inch t 'I.. T\Iax . .-:--- '" ;I.. "'. 3 /4 inch Crushed Rock or 3 ~'. .... . I~ Mirafi Gl00N or Equivalent ~ '.~ ~ v .. ,,' : ~~. '" . • b V .' --.. 12.11 I-- [ 6-inch Minimum Waterproof Back of Wall Per Architect's Specifications Goof,bric compl"'IY~ •.• ~. Top of Ground r m Concr,te Slab l---~-~ \\!rapped Around Rock ;< 0···. !. . Minimum 4-inch Diameter Perforated Pipe PVC Schedule 40 ~!/ RETAINING WALL SUBDRAIN DETAIL No Scale /'Y~ 6-indi Minimum I r-------------~--------~------~ • ~ ~ PROPOSED SINGLE-FAMILY RESIDENCE ~~W ~ U El Fuerte Street, Lot 69, Carlsbad, California I CHRISTIAN WHEELER r'CI'lrRI-":C 4925 ~mRCL'RY STRI\lT I SAN 1)11 ,GO, CALlI'ORNI:\ 92111 TEL (858) 496-9760 FAX. (858) 469-9758 BY: lIe D;\'l'E: September 2005 JOB NO.: 2050527.01 PL:\TENO.: 6 I I I I I I I I I I I I I I I I I I " C\"X7E 2050527.01 September 2005 Appendix A, Page A-1 REFERENCES Anderson,J.G.; Rockwell, R.K. and Agnew, D.C., 1989, Past and Po~sible Future Earthquakes of Significance to the San Diego Region, Earthquake Spectra, Volume 5, No.2, 1989. Blake, T. F., 2000, Documentation for Eqfault Version 3.0, Thomas F. Blake Computer Services and Software. Boore, David M.,Joyner, \"Xlilliam B., and Fwnal, Thomas E., 1997, "Empirical Near-Squrce Attenuation Relationships for Horizontal and Vertical Components of Peak Ground Acceleration, Peak Gmund Velocity, and Pseudo-Absolute Acceleration Response Spectra", in Seismological Research Letters, Volume 68, Number 1,January/February 1997. Countywide Flood Insurance Rate Maps, Panels 1051F, prepared by the Federal Emergency Management Agency, effective date June 19,1997. Hart, E.W., 1994, Fault-Rupture Hazard Zones in California, California Di,rision ofI:v1ines and Geology Special Publication 42. Jennings, C.\'{T., 1975, Fault Map of California, California Division oHvfines and Geology, Map No.1, Scale 1:750,000. Kern, P., 1989, Earthquakes and Faults in San Diego County, Pickle Press, 73 pp. Wesnousky, 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. I I I I I I I I I I I I I I I I I I I C\\1E 2050527.01 September 2005 Appendix B, Page B-1 RECOMMENDED GRADING SPECIFICATIONS -GENERAL PROVISIONS GENERAL INTENT PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET. LOT 69 CARLSBAD. CALIFORNIA The intent of these specifications is to establish procedures for clearing, compacting natural ground, preparing areas to be filled, and placing 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 contained hereinafter 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 wEtten communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian \X'heeler Engineering shall be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessalY that the Geotechnical Engineer or his representative 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 assjst the Geotechnical 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, substandard conditions are encounter,ed, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction,_ adverse weather, etc., construction should be stopped until the conditions 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 follo'\ving American Society for Testing and Materials test methods: I I I I I I I I I I I I I I I I I I ·1 . C\V'E 2050527.01 September 2005 Maximum Density & Optimum Moisture Content -ASTM D-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 operations shall be removed, and legally disposed of. All areas disturbed by site grading should be left in a neat and finished ~ppearance, free from unsightly debris. After clearing or benching the natural ground, 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. WIlen the slope of the natural ground receiving fill exceeds 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. The 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 receiving 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 abandoned buried structures encountered during grading operations must be totally removed. All undergrqund utilities to be abandoned beneath any proposed structure should be removed from w~thin 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 not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drains and water lines .. Any buried structures or utilities not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recommendation will be necessary. All water wells which 'will be -abandoned should be backfilled and capped 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 I I I I I I I I I I I I, I 'I I I I I I . C\'{!E 2050527.01 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 MATERIAL 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 to provide satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any import material shall be approved by die 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 to be efficiendy applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the specified minimum degree of compaction with equipment of adequate slze to economically compact the layer. Compaction equipment should either be specifically designed for soil compaction or of proven reliability. The minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminary geotechnical investigation report. Wlhen the structural fIll material includes rocks, no rocks will be allowed to nest and, all voids must' be carefully filled with soil such that the minimum degree of compaction recommended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in non- structural f.tlls, is discussed in the geotechnical report, when applicable. , Field observation and compaction tests to estimate the degree of compaction of the fill will be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be at the Geotechnical Engineer's discretion. \X1hen the compaction test indicates that a particular layer is at less than the required degree o.f compaction, dle layer shall be reworked to the satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. I 'I I I I I I I I I I I I I I I C\'{1E 2050527.01 September 2005 Appendix B, Page B-4 Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaetion by sheepsfoot roller 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 maximum dry density or the degree of compaction specified in the Special Provisions ~ection of this specification. The compaction operation on the slopes shall ?e continued until the' Geotechnical 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. \'X','here 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 Engi?eering Geologist shall inspect cut slopes excavated in rock or lithified formational material durin~ the ,grading operations at intervals determined at his discretion. If any conditions not anticipated in the preliminary report such as perched 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 determine if mitigating lneasures are necessary. Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ' ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shall be made during the fuling 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 I I I I I I I I I I I I I I I I ,I I .; CWE 2050527.01 September 2005 Appendix B, Page B-5 the observation and testing 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. RECOMMENDED 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: Oversized fill material is generally defined herein as rocks or lumps of soil over 6 inches in diameter. Oversized materials should not be placed in fill unl~ss recommendations of 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. TRANSITION LOTS: \\1here 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 suuctural 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. "