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HomeMy WebLinkAboutCT 02-06; KIRGIS TENTATIVE MAP; UPDATED GEOTECHNICAL INVESTIGATION; 2011-08-01CHRISTIAN WHEELER ENGINEERING UPDATED GEOTECHNICAL INVESTIGATION REPORT KIRGIS SUBDIVISION CARLSBAD TRACT 02-06 TWAIN AVENGE CARLSBAD, CALIFORNIA SUBMITTED TO BRIAN AND GAYL HYNEK PO BOX 401 GILROY, CAUFORNIA 95021-0451 SUBMITTED BY CHRISTL\N WHEELER ENGINEERING 3980 HOME AVENGE SAN DIEGO, CALIFORNLA 92105 r o o Ul o 3980 Home Avenue « San Diego, CA 92105 * 61 9-550-1700 <D FAX 619-550-1701 < CHRISTIAN WHEELER ENGINEERING July 6,2011 Brian and Gayl Hynek P.O. Box 401 Gilroy, Califomia 95021-0451 CWE 2110148.01 SUBJECn": Updated Geotechnical Investigation Report, Kirgis Subdivision, Carlsbad Tract 02-00, Twain Avenue, Carlsbad, Califomia. Reference: Report of Preliminary Geotechnical Investigation, Proposed Five-Lot Residential Project, APN 212-010-03, West of Faraday Road, Carlsbad, Ca.'\i£otmii,prepand by Christian Wheeler Engineering, CWE Project No. 201.116.01, datedUatch. 14, 2001. Dear and ^^s. Hjmek: In accordance with your request, and our proposal and agreement dated -^^^^ 2,2011, Christian Wheeler Engineering has completed an updated geotechnical investigation report for the subject project. We are presenting herewith a report of our findings and recommendations. If you have any questions after reviewing this report, please do not hesitate to contact om office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, CHRISTIAN WHEELER ENGINEERING Charles H. Christian, R.G.E. #00215 CHC:TSW:DBA Disttibution: (2) Submitted (1) david@.lmco.net 3980 Home Avenue * San Diego, CA 92105 o 61 9-550-1700 * FAX 619-550-1701 TABLE OF CONTENTS PAGE Introduction and Project Description 1 Project Scope 2 Findings 2 Site Description 2 General Geology and Subsurface Conditions 3 Geologic Setting and Soil Description 3 Topsoil 3 Subsoil 3 Slopewash 4 Old Paralic Deposits 4 Santiago Formation 4 Goundwater 4 Conclusions 5 Recommendations 6 Grading and Earthwork 6 General 6 Pre-Grade Meeting 6 Observation of Grading 6 Site Preparation 7 Transition Building Pads 7 Select Grading 7 Cut and Fill Slope Construction 7 Excavation Characteristics 8 Excavation Characteristics 8 Sediment Traps 8 Processing of Fill Areas 8 Compaction and Method of Filling 8 Surface Drainage 8 Grading Plan Review 9 Sbpe Stability 9 General 9 Erosion Control 9 Foundations 10 General 10 Footing Dimensions 10 Bearing Capacity 10 Foundation Reinforcement 10 Post-Tensioned Foundations 11 Lateral Load Resistance 11 Seismic Design Factors 11 Settlement Characteristics 12 Expansive Characteristics 12 Foundation Plan Review 12 Foundation Excavation Observation 13 Soluble Sufates 13 On-Grade Slab 13 General 13 Interior Floor Slab 13 Under-Slab Vapor Retarders 13 Exterior Concrete Slab-On-Grade 14 CWE 2110148.01 Kirgis Subdivision, Carlsbad Tract 802-06 Twain Avenue, Carlsbad, Califomia Swimming Pools 14 Masonry Earth Retaining Walls 15 Foundations 15 Passive Pressvure 15 Active Pressures 15 Waterproofing And Subdrain 15 Backfill 15 Limitations 16 Review, Observation and Testing. 16 Uniformity of Conditions 16 Change in Scope 16 Time Limitations 17 Professional Standard 17 Client's Responsibility 17 ATTACHMENTS PLATES Plate 1 Plate 2 Plate 3 Site Plan & Geotechnical Map Fill Over Cut Slope DetaU Retaining Wall Subdrain Detail TABLES Table 1 Seismic Design Factors APPENDICES Appendix A Data From CWE 201.116 Geotechnical Report Appendix B References Appendix C Recommended Grading Specifications — General Provisions CWE 2110148.01 Kirgis Subdivision, Carlsbad Tract 802-06 Twain Avenue, Carlsbad, Califomia CHRISTIAN WHEELER ENGINEERING UPDATED GEOTECHNICAL ESJVESTIGATION REPORT KIRGIS SUBDIVISION CARLSBADS T ACT 02-06 TWAIN AVENUE CARLSBAD. CALIFO NIA INTRODUCTION AND PROJECT DESCRIPTION This report presents an updated geotechnical report for the subject residential subdivision and associated improvements to be developed at the southem end of Twain Avenue, in the city of Carlsbad, Califomia. Figure Number 1, presented on the following page, provides a vicinity map showing the location of the project. It is our understanding that the subject project will consist of a five-lot residential subdivision with associated improvements, including a short access street. It is anticipated that the stmctures will be one and/or two stories high, and of wood-frame constmction. Shallow foundations and conventional concrete slab-on-grade floor systems are anticipated. However, post-tensioned foundations may be utilized. Based on the available plans, grading will consist of cuts and fills of up to about 30 feet and 19 feet in depth, respectively. Proposed cut and fill slopes will be graded at a 2:1 (horizontal to vertical) or flatter inclination, and extend to a maximum height of about 20 feet and 27 feet, respectively. To aid in the preparation of this report, we were provided with a set of undated grading and erosion plans prepared by Landmark Consulting. A copy of the grading plan has been used as the base for our Site Plan and Geotechnical Map, and is included herein as Plate No. 1. In addition, we have reviewed our " eport R of Geotechnical Investigation, Proposed Five-Lot Subdivision", dated March 14, 2001. Appropriate data form this geotechnical report is presented in Appendix A. This data was used in the preparation of this updated report. This report has been prepared for the exclusive use of Brian and Gayl Hynek and their design consultants for specific application to the project described herein. Should the project be changed in any way, the 3980 Home Avenue * San Diego, CA 92105 * 619-550-1700 CP FAX 619-550-1 701 SITE VICINITY MAP (Adapted from Thomas Brothers Maps) KIRGIS SUBDIVISrON CARLSBADS TRACT 02-06 TWAIN AVENUE CARLSBAD. CALIFORNIA i North SITE CWE 2110148.01 July 2011 Figure 1 CWE 2110148.01 July 6,2011 Page No. 2 modified plans should be submitted to Christian Wheeler Engineering for review to detemiine their conformance with our recommendations and to detemiine whether 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 aU other warranties, express or implied. PROJECT SCOPE The scope of our updated report included a surface reconnaissance, and a review of the aforementioned documents. Our scope of service did not include assessment of hazardous substance contamination, recommendations to prevent floor slab moisture intmsion or the formation of mold within the stmctures, evaluation or design of storm water infiltration facilities, or any other services not specifically described in the scope of services presented below. More specifically, the intent of this updated report was to: a) Visit site to provide a surficial reconnaissance of the current site conditions; b) Review the referenced geotechnical report and grading plans; c) Provide updated seismic design parameters as required by the 2010 edition of the Califomia Building Code; d) Present updated recommendations for the geotechnical aspects of the proposed site development as presently proposed; FINDINGS SITE DESCRIPTION The subject site is a nearly rectangular-shaped parcel of land approximately 21.9 acres in area, located at the southem end of Twain Avenue, in the City of Carlsbad, Califomia. The site is ftirther identified as Assessor's Parcel Number 212-010-03. Undeveloped canyon lands bound the site to the west, south, and east, while a residential subdivision bounds the site to the north. CWE 2110148.01 July 6,2011 Page No. 3 The site is primarily undeveloped; however, numerous small "outbuildings" were scattered across the site at the time of our site reconnaissance and subsurface exploration. The approximate locations of these "outbuildings" are shown on the site plan attached herewith as Plate No. 1. Additionally, relatively minor amounts of trash and debris, were observed across the surface of the site. Vegetation on the upper portions of the site consists of sparse to relatively dense indigenous bmsh and small to medium sized trees. Within the descending, canyon areas of the site, the on-site vegetation was observed to consist of moderately dense to very dense indigenous bmsh and small to medium size trees. In general, a gently sloping mesa top that generaUy descends to the south characterizes the uppermost, northem portion of the site. Moderately steep canyon lands descend to south, east, and west from the uppermost, mesa top area of the site. The existing on-site elevations within those portions of the site to receive improvements range from about 330 feet in the northem portion of the site to about 270 feet in the southwestem portion ofthe site. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located in the Coastal Plains Physiographic Province of San Diego County and is underlain by a relatively minor amount of native residuum, Quatemary-age old paralic deposits, and Cretaceous-age deposits of the Santiago Formation. The following provides a discussion, based on our subsurface explorations and our past experience with nearby projects, of the soU types expected to be encountered beneath the property. TOPSOIL: Native topsoU was encountered at the surface in most of our exploratory test trenches. The topsoU layer has an approximate thickness of one foot The topsoU material generaUy consists of dark brown, sUty sand (SM) that is typicaUy moist and loose in consistency. It shoiUd be noted that topsoU was not encountered in our test trench T-9, excavated in the northwest portion of the site. These deposits were judged to have a low potential for expansion (EK50). SUBSOIL: A layer of native subsoU was encountered within our exploratory test trenches excavated in the northern, eastern, and southeastem portions of the proposed improvement area. The subsoU was generaUy noted below the topsoU layer, but was also noted at the surface within the northeast portion of the site. The thickness of the subsoU layer ranged from approximately one foot to IV2 feet The subsoU was noted to primarily consist of medium brown, dayey sand (SC). The subsoU was also noted as being generaUy moist and loose to medium dense. These deposits were judged to have a moderate potential for expansion (EI between 51-90). CWE 2110148.01 July 6,2011 Page No. 4 SLXDPEWASH (Qsw) : A layer of slopewash material was noted below the topsoU layer within our exploratory test trenches excavated in the southwest portion of the proposed improvement area. The layer had an approximate thickness ranging from VA to 2 feet The materials within the slopewash layer generaUy consisted of dark brown, sandy clay (CL) that were wet and soft with a slight amount of gravel and cobble. These deposits were judged to have a moderate potential for expansion (EI between 51-90). OLD PARALIC DEPOSITS (Qop): Underlying the topsoU and subsoU layers, a layer of old paralic deposits manties the northern, eastern, and southeastem portions of the proposed improvement area. These deposits were identified in the referenced geotechnical report as terrace deposits. The approximate location of the contact between the old paralic deposits and underiying Santiago Formation is shown on Plate No. 1. This contact typicaUy occurs at an elevation of 310 feet GeneraUy, the layer of terrace deposits is thickest within the upper areas in the eastem portion of the improvement area, and thins towards the lower portions. The terrace deposits generaUy consisted of orangish-brown, clayey sand (SQ that was moist and dense to very dense with some gravel and cobble. The old paraUc deposits were found to possess a very low expansion potential (EI=6). SANTIAGO FORMATION (Tsa): The site is ultimatdy underlain by Tertiary-age deposits of the Santiago Formation. The formational materials were noted below the terrace deposits in the northern, eastern, and southeastem portions ofthe proposed improvement area and bdow the topsoil, subsoil, and slopewash layers in the south-southwestern portions. The materials ofthe Santiago Formation maiiUy consisted of light brown to light orangish-brown, clayey sand (SQ and light brown to white, sUty sand (SM). The formational materials also consisted of lesser amounts of light olive brown, sandy clay (CL). The formational materials were typicaUy moist The sandy portions of the Santiago Fomiation were dense to very dense \diUe the clayey portions were very stiff to hard. The sandy portions of the Santiago Formation were judged to have a low expansion potential (EK50). The clayey portions of the Santiago Formation, which comprise a relativdy smaU amount of the formational material, were found to possess a medium expansion potential (EI_ 85). GROUNDWATER: No groundwater or seepage was encountered in any of the areas of the site investigated. However, it should be recognized that minor groundwater seepage problems may occur after development of a site even where none were present before development These are usuaUy minor phenomena and are often the result of an alteration in drainage pattems and/or an increase in irrigation water. Based on the permeability characteristics of the soU and the antidpated usage and development, it CWE 2110148.01 July 6,2011 Page No. 5 is our opinion that any seepage problems which may occur wiU be minor in extent. It is fiirther our opinion that these problems can be most effectivdy corrected on an individual basis if and when they occur CONCLUSIONS In general, our findings indicate that the subject property is suitable for the construction of the proposed subdivision and associated improvements, provided the recommendations provided herein are foUowed. The main geotechnical conditions encountered that affect the proposed devdopment are potentiaUy compressible surficial soUs, expansive soUs, cut/fiU transitions, and fiU thickness differentials. These conditions are discussed hereinafter. It should be recognized that some of the recommendations provided hereinafter to mitigate a certain potentiaUy adverse condition may also be applicable to another condition. • A relativdy thin mantie of compressible topsoU, subsoU, and slopewash ranging between about two to three feet in thickness caps the site. These materials are considered unsuitable, in their present condition, for the support of setdement sensitive improvements, and should be removed and replaced as compacted filL • A relativdy smaU percentage of the Santiago fomiation deposits encountered in our trenches was found to be moderatdy expansive (EI=85). It is recommended that sdect grading be performed to mitigate this condition. It shovUd be realized that Santiago Fomiation deposits are inherentiy highly heterogeneous, and the relative amounts of different soUs exposed in our trenches may not be representative of the as-graded conditions. If sdect grading caimot be performed due to the lack of suffident low expansive soUs, the foundation recommendations contained in this report may have to be changed. • Proposed grading for Lot 3 wiU result in a cut/fiU transition. This condition wUl also occur to a lesser extent in Lots 1 and 2. Stmctures and improvements spanning cut/fiU transitions may experience detrimental differential settiements due to the different compression characteristics of native and fiU soUs. In order to mitigate this condition, it is reconimended that the cut portion of the lot be undercut as described hereinafter. Undercutting the cut portions of the lots wiU also facilitate fiiture drainage, trenching and landscaping. • Depending on their locations, fiU thicknesses differentials exceeding ten feet may exist under the proposed stmctures in Lots 3,4, and 5. In order to mitigate this condition, it may be necessary to CWE 2110148.01 July 6,2011 Page No. 6 increase the embedment depth and reinforcement of the foundations, and to increase the thickness and reinforcement of the on-grade floor slabs. • Temporary sediment traps are proposed adjacent to the top of proposed fiU slopes on aU five lots. Sediment traps adjacent to the top of slopes are not advised due to the potential for water infiltration into the underiying fiU soUs. This condition may detrimentaUy affect the soils underlying the sediment traps and adjacent slopes. If sediment traps must be located as currentiy proposed, they shoidd be designed, constmcted, and maintained such that no water infiltrates into the underlying soil It is our understanding that the design, constmction, and maintenance of the sediment traps wiU be performed by others than Christian Wheder Engineering. The site is located in an area that is relativdy free of geologic hazards that wiU have a significant effect on the proposed constmction. The most likdy geologic hazard that could affect the site is ground shaking due to sdsmic activity along one of the regional active faults. However, constmction in accordance with the requirements of the 2007 edition of the Califomia BuUding Code and the local govemmental agendes should provide a levd of life-safety suitable for the type of devdopment proposed. RECOMMENDATIONS GRADING AND EARTHWORK GENERAL: All grading should conform to the guideUnes presented in Appendix J of the Califomia BuUding Code, the niinimum requirements of the City of Carlsbad, and the Recommended Grading Specifications and Special Provisions attached hereto, except where specificaUy superseded in the text of this report. PRE-GRADE MEETING: It is recommended that a pre-grade meeting, induding the owner's representative, grading contractor and a representative from Christian Wheder Engineering, take place to discuss the recommendations of this report and address any issues that may affect grading and constmction operations. OBSERVATION OF GRADING: Observation by die Geotechnical Consultant is essential during the mass grading operation to confirm conditions antidpated by our investigation, to aUow adjustments in design criteria to reflect actual fidd conditions exposed, and to detemiine that the grading proceeds in CWE 2110148.01 July 6,2011 Page No. 7 general accordance with the recommendations contained herein. Continuous or periodic observation shoidd be provided at the discretion of the (jeotechnical Consultant SITE PREPARATION: Site preparation should begin with the removal of aU existing improvements and trash, as weU as any existing vegetation from the areas of the site to be graded. The debris resulting from this operation should be disposed of off-site. This should indude aU root baUs from trees, aU natural brush and aU significant root material Existing topsoil, subsoil, and slopewash underlying proposed settiement-sensitive improvements, including aU proposed fiUs, should be removed in their entirety. Based on the geotechnical information available, the antidpated removal depths range from about two feet to three feet. However, deeper removals may be needed in areas not investigated or due to unforeseen conditions. Actual removal depths wiU be detemiined by our representative. Where necessary to achieve planned site grades, the removed materials may be replaced as compacted fiU provided they are thoroughly mixed and moisture conditioned prior to placement TRANSITION BUILDING PADS: It is recommended tiiat formational soUs underlying die cut portion of the proposed transition lots be undercut to a minimum depth of four feet (3 feet in previous report) bdow finish pad grade, or two feet bdow the bottom of footings (one foot below retaining waU footing keys) whichever is deepest. The undercuts shoidd be performed in such a way that low areas with impaired drainage are not created. If identified, future swimming pool areas shoidd also be undercut. Undercut areas should be backfiUed with properly compacted, low expansive fiU (EK50). SELECT GRADING: Portions of the Santiago Formation were determined to possess a medium expansive potentiaL Expansive soUs should not be placed within five feet from finish pad grade, and ten feet from the face of slopes. In addition, expansive soils within five feet from finish pad grade in proposed cut areas that are undercut, shoidd be removed and replaced with low expansive fiU (EI<50) compacted to at least 90 percent CUT AND FILL SLOPE CONSTRUCTION: Cut and fiU slopes may be constmcted at an inclination of 2:1 or flatter (horizontal to vertical). Compaction of fiU slopes shoidd be performed by back-roUing with a sheepsfoot compactor at vertical intervals of four feet or less as the fiU is being placed, and track-walking the face of the slope when the slope is completed. As an altemative, the fiU slopes may be overfiUed by at least three feet and then cut back to the compacted core at the design Une and grade. Keys shoidd be made at the toe of fiU slopes in accordance with the recommendations presented under "Compaction and Method of FiUing." A subdrain is reconimended for transition fiU over cut slopes. A subdrain detaU is provided in the attached Plate No. 2. CWE 2110148.01 July 6,2011 Page No. 8 EXCAVATION CHARACTERISTICS: It is antidpated diat the cuts proposed in the aforementioned grading plans may be achieved with conventional, large heavy-duty grading equipment in good working order. However, concretions requiring special grading and handling consideration may be encountered within the Santiago FormatioiL In addition, zones of very dense deposits that are difficult to excavate with light trenching equipment may be encountered within the Santiago Formation. SEDIMENT TRAPS: A temporary sediment trap consisting of a smaU detention basin is proposed for each of the five lots. Design, constmction, and maintenance of the sediment traps wiU be performed by others than Christian Wheder Engineering. When abandoned, the traps should be backfiUed with low expansive fiU (EK50) compacted to at least 90 percent PROCESSING FILL AREAS: Prior to placing any new fiU soils or constmcting any new improvements in areas that have been deaned out to receive fiU, the exposed soUs shoidd be scarified to a depth of about 12 inches, moisture-conditioned, and compacted to at least 90 percent relative compaction. In areas to support fiU slopes, keys should be cut into the competent supporting materials. The keys should be at least ten feet wide, and be sloped back into the hiUside at least two percent The keys should extend at least one foot into the competent supporting materials. Where the existing ground has a slope of 5:1 (horizontal to vertical) or steeper, it should be benched into as the fiU extends upward from the keyway. COMPACTION AND METHOD OF FILLING: AU fiU and backfiU placed at die site should be compacted to a rdative compaction of at least 90 percent of its maximum dry density as determined by ASTM Laboratory Test D1557. FiUs should be placed at or sUghtiy above optimum moisture content, in lifts six to eight inches thick, with each lift compacted by mechanical means. FiUs shoidd consist of approved earth material, free of trash or debris, roots, vegetation, or other materials determined to be unsuitable by the (jeotechnical Consultant FiU material should be free of rocks or lumps of soU in excess of twdve inches in maximum dimension, and free of rocks over six inches in diameter within the upper three feet of pad grade. Utility trench backfiU within five feet of the proposed stmctures and beneath driveways, concrete flatwork, and pavements shoidd be compacted to a minimum of 90 percent of its maximum dry density. SURFACE DRAINAGE: The drainage around the proposed improvements shoidd be designed to coUect and direct surface water away from proposed improvements and the top of slopes toward appropriate drainage facUities. Rain gutters with downspouts that discharge runoff away from the stmctures into controUed drainage devices are recommended. CWE 2110148.01 July 6,2011 Page No. 9 The ground around the proposed improvements should be graded so that surface water flows rapidly away from the improvements without ponding. In general, we recommend that the ground adjacent to stmctures be sloped away at a minimum gradient of two percent Densdy vegetated areas where runoff can be impaired should have a minimum gradient of five percent for the first five feet from the stmcture. Drainage pattems provided at the time of fine grading shoidd be maintained throughout the life ofthe proposed inprovements. Site irrigation should be limited to the minimum necessary to sustain landscape growth. Over watering should be avoided. Shoidd excessive irrigation, impaired drainage, or unusuaUy high rainfaU occur, zones of wet or saturated soU may devdop. GRADING PIAN 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 antidpated devdopment plans. SLOPE STABIUTY GENERAL: AU slopes at the subject devdopment shoidd be constmcted at a slope ratio of 2.0 horizontal units to 1.0 vertical unit (2:1) or flatter. Maximum cut and fiU slope heights wiU be less than about 20 feet and 27 feet, respectivdy. Based on the strength parameters of the on-site soUs in their natural and mechanicaUy conipacted states, it is our opinion that the proposed slopes wiU be stable in regards to deep- seated slope faUure and surficial slope faUure. AU fiU slopes shoidd be constructed in accordance with the grading recommendations presented above. EROSION CONTROL: The placement of cohesionless soUs at the face of slopes should be avoided. Slopes should be planted as soon as feasible after grading. Sloughing, deep rilling and slumping of surficial sods may be antidpated if slopes are left unplanted for a long period of time, espedaUy during the rainy season. Care should be taken to ensure the proper drainage of aU surface runoff away from the slope face. Saturation of the slope caused by excessive or improperly chaimded mnoff could detrimentaUy affect the surficial StabiUty of the slope. Irrigation on and adjacent to slopes shoidd be carefidly monitored to insure that only the minimum amount necessary to sustain plant life is used. Over-irrigating could not only be erosive but may significandy increase the chance for slope surficial stability problems and should be avoided. CWE 2110148.01 July 6,2011 Page No. 10 FOUNDATIONS GENERAL: Based on our findings and engineering judgment, the proposed structures may be supported by conventional continuous and isolated spread footings, provided the site is prepared as reconimended in this report As an altemative post-tensioned foundations may be utilized. The foUowing recommendations are considered the minimum based on soU conditions and are not intended to be Ueu of stmctural considerations. AU foundations should be designed by a qualified stmctural engineer. FOOTING DIMENSIONS: Spread footings supporting proposed single-and two-story stmctures shoidd have a minimum embedment depth of 12 inches and 18 inches bdow lowest finish pad grade, respectivdy. Continuous footings for single-and two-story stmctures should have a minimum width of 12 inches and 15 inches, respectivdy. Isolated footings shoidd have a minimum width of 24 inches. Minimum dimensions for footings supporting exterior improvements should be 12 inches in depth and width. Minimum dimensions for footings supporting exterior retaining waUs should be 18 inches in depth and 24 inches in width. Footings located adjacent to slopes should be extended to a depth such that a minimum horizontal distance of eight feet exists between the bottom of the footing and the face of the slope. For retaining waU footings, a ten-foot horizontal setback is recommended. The footing setback distance from the top of slopes may be modified by using deepened footings. Footing setback is measured from competent soU and shoidd neglect any loose or soft native soUs that may occur at the top of a natural slope. Plans for any footings that wiU not comply with the specified setbacks shoidd be submitted to the Geotechnical Engineer for specific review and approval prior to constmction. BEARING CAPACITY: Conventional continuous spread footings with a minimum embedment of 12 inches and width of 12 inches may be designed for an aUowable soU bearing pressure of 2,500 pounds per square foot This value may be increased by 700 pounds per square foot for each additional foot of embedment and 400 pounds per square foot for each additional foot of width up to a maximum of 4,000 pounds per square foot The bearing value may also be increased by one-third for combinations of temporary loads such as those due to wind or sdsmic loads. FOUNDATION REINFORCEMENT: The project stmctural engineer should provide foundation reinforcement recommendations. However, based on the antidpated soU conditions, we recommend that the niinimum reinforcing for continuous footings should consist of at least two No. 5 bars positioned near the bottom of the footing and two No. 5 bars positioned near the top of the footing. CWE 2110148.01 July 6,2011 Page No. 11 POST-TENSIONED FOUNDATIONS: Post-Tensioned foundations may be utiUzed for tiie support of the subject stmctures. We are providing in tabular form bdow the post tension related design parameters from the Post Tensioning Instimte, 3"* edition. TABLE I: POST-TENSIONED FOUNDATIONS Post-Tensioning Institute (PTI) - 3^ Edition Edge Moistuie Vuution, Cm Center Lift (ft) 9.0 EdzeUft(ft) 5.4 Di£ktentul S<al Movement, ym Center Uft (in) .19 EdjieUftdn) .41 A minimum depth of 12 inches bdow adjacent finished grade is recommended for perimeter beams. SoU bearing values provided in the bearing capadty paragraph are also appUcable for post tensioned foundations. Footings located adjacent to slopes shoidd be extended to a depth such that a minimum horizontal distance of eight feet exists between the bottom of the footing and the face of the slope. Footing setback is measured from competent soU and shoidd neglect any loose or soft native soils that may occur at the top of a natural slope. LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by fiiction between the bottom of the footing and the supporting soil, and by the passive pressure against the footing. The coeffident of fiiction between concrete and sod 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 This assumes 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. The upper 12 inches of footing embedment should not be considered when calculating passive pressures, unless the footing abuts a concrete slab-on-grade or a paved surface. SEISMIC DESIGN FA(]TORS: Provided below are sdsmic design factors appUcable to the subject site. The sdsmic design factors were determined in accordance with the 2010 Califomia BuUding Code. The site coefficients and adjusted maximum considered earthquake spectral response acceleration parameters are presented here CWE 2110148.01 July 6,2011 Page No. 12 TABLE II: SEISMIC DESIGN FACTORS Site Coordinates: Latitude Longitude 33.138° -117.299° Site Class D Site Coefficient Fa 1.024 Site Coefficient Fy 1.55 Spectral Response Accderation at Short Periods Ss 1.191 Spectral Response Accderation at 1 Second Period Si 0.450 SMS=FaSs 1.219 SMI=FVSI 0.698 SDS=2/3*SMS 0.813 SDI_2/3*SMI 0.465 Probable ground shaking levels at the site could range from sUght to moderate, depending on such factors as the magnitude of the seismic event and the distance to the epicenter. It is likdy that the site wiU experience the effects of at least one moderate to large earthquake during the life of the proposed improvements. SETTLEMENT CHARACTERISTICS: The antidpated total and differential foundation settiement is expected to be less than about 1 inch and 1 inch over 40 feet respectively, provided the recommendations presented in this report are foUowed. It should be recognized that minor cracks normaUy occur in concrete slabs and foundations due to shrinkage during curing or redistribution of stresses, therefore some cracks should be antidpated. Such cracks are not necessarily an indication of excessive vertical movements. EXPANSIVE CHARACTTERISTICS: Provided that the recommendations contained in this report are implemented, the prevailing foundation soils are expected to have a low expansive potential (EI < 50). The recommendations presented in this report reflect this condition. FOUNDATION PLAN REVIEW: The final foundation plan and accompanying detaUs and notes should be submitted to this office for review. The intent of our review wiU be to verify that the plans used for construction reflect the minimum dimensioning and reinforcing criteria presented in this section and that no additional criteria are required due to changes in the foundation type or layout It is not our intent to review stmctural plans, notes, details, or calculations to verify that the design engineer has correctiy appUed the geotechnical design values. It is the responsibiUty of the design engineer to properly design/specify the foundations and other stmctural elements based on the requirements of the stracture and considering the information presented in this report. CWE 2110148.01 July 6,2011 Page No. 13 FOUNDATION EXCAVATION OBSERVATION: AU foundation excavations should be observed by a representative of this office prior to the placement of forms or reinforcement in order to verify that the footings have the proper dimensions and that the soU conditions are as antidpated. SOLUBLE SUFATES The water soluble sulfate content of foundation soUs shoidd be determined after grading in accordance with CaUfornia Test Method 417. Nevertheless, Type II modified Portland cement is reconimended for concrete in contact with soil ON-GRADE SLABS GENERAL: It is our understanding that if conventional foundations are utUized for the support of the proposed stmctures, the floor system for the proposed stmctures wiU consist ofan on-grade concrete slab. The foUowing recommendations are considered the minimum slab requirements based on the antidpated soU conditions, are not intended in Ueu of stmctural considerations. INTERIOR FLOOR SLABS: The niinimum floor slab thickness for Lots 1,2 and 3 should be four inches (actual), and the floor slab should be reinforced with at least No. 3 reinforcing bars placed at 18 inches on center each way. The minimum floor slab thickness for Lots 4 and 5 should be five inches (actual), and the floor slab should be rdnforced with at least No. 4 reinforcing bars placed at 12 inches on center each way. Slab reinforcement should be supported on chairs such that the reinforcing bars are positioned at mid-hdght in the floor slab. The slab reinforcement shoidd extend kito the perimeter foundations at least six inches. The garage slab may be constmcted independent of the garage perimeter footings, but the slab and foundation should have a fdt strip between them. If the garage slab and footings are constmcted monoUthicaUy, the slab reinforcement should extend into the perimeter foundations at least six inches. UNDER-SLAB VAPOR RETARDERS: Steps should be taken to minimize the transmission of moisture vapor from the subsoU through the interior slabs where it can potentiaUy damage the interior floor coverings. Local industry standards typicaUy indude the placement of a vapor retarder, such as plastic, in a layer of coarse sand placed directiy beneath the concrete slab. Two inches of sand and two inches of sand are typicaUy used above and bdow the plastic, respectivdy. This is the most common under-slab vapor retarder system used in San Diego County. The vapor retarder shoidd be at least 15-mU plastic with sealed seams and should extend at least 12 inches down the sides of the interior and perimeter footings. The sand CWE 2110148.01 July 6,2011 Page No. 14 should have a sand equivalent of at least 30, and contain less than 10% passing the Number 100 sieve and less than 5% passing the Number 200 sieve. The membrane should be placed in accordance with the recommendation and consideration of ACI 302, "Guide for Concrete Floor and Slab Constmction" and ASTM El643, "Standards Practice for Installation of Water Vapor Retarder Used in Contact with Earth or Granular FUl Under Concrete Slabs". EXTERIOR CONCRETE SLAB-ON-GRADE Exterior concrete slabs on grade should have a niinimum thickness of 4 inches and shoidd be reinforced with at least No 3. bars placed at 18 inches on center each way (ocew). Driveway slabs should have a minimum thickness of 5 inches and be reinforced with at least No. 4 bars placed at 12 inches ocew. AU slabs should be provided with weakened plane joints in accordance with the American Concrete Institote (ACI) guideUnes. Altemative pattems consistent with ACI guideUnes can also be used. A concrete mix with a 1-inch maximum aggregate size and a water/cement ratio of less tiian 0.6 is reconimended for exterior slabs. Lower water content wiU decrease the potential for shrinkage cracks. Consideration should be given to using a concrete mix for the driveway that has a minimum compressive strength of 3,000 pounds per square inch. This suggestion is meant to address early driveway use prior to fuU concrete curing. Both coarse and fine a^egate should conform to the latest edition of the "Standard Specifications for PubUc Works Constmction" ('Greenbook"). Special attention shoidd be paid to the method of concrete curing to reduce the potential for excessive shrinkage and resultant random cracking. It shoidd be recognized that minor cracks occur normaUy in concrete slabs due to shrinkage. Some shrinkage cracks should be expected and are not necessarily and indication of excessive movement or stmctural distress. SWIMMING POOLS Swimming pools may be constmcted as part of the proposed development or by future individual homeowners. If the proposed pool is a settiement sensitive vanishing edge pool or a zero edge pool, it is recommended that it be founded in the formational soUs underlying the compacted fiU. Depending on the pool location, this recommendation may necessitate a foundation system consisting of concrete cast- in-place piers. Appropriate foundation recommendations wiU be provided by this office after the proposed swimming pool layout is avaUable. CWE2110148.01 July6,2011 PageNo. 15 EARTH RETAINING WALLS FOUNDATIONS: Foundations for proposed retaining waUs should be constmcted in accordance with the recommendations for shaUow foundations presented previously in this report. PASSIVE PRESSURE: The passive pressure for the design of sUding resistance for the proposed retaining waU footings 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 coeffident of fiiction for concrete to soU may be assumed to be 0.35 for the resistance to lateral movement When combining fiictional and passive resistance, the fiiction should be reduced by one-third. ACTIVE PRESSURE: The lateral soU pressure for the design of unrestrained earth retaining stmctures with level backfiU may be assumed to be equivalent to the pressure of a fluid weighing 35 pounds per cubic foot (pcf). An additional 13 pcf should be added to the above value for a 2:1 (horizontal to vertical) sloping backfiU condition. These pressures do not consider any other surcharge. If any are antidpated, this office should be contacted for the necessary increase in sod pressure. These values are based on a drained, non-detrimentaUy expansive (EI <50) backfiU condition. The project stmctural engineer may dedde that some of the proposed retaining waUs shoidd be designed to resist sdsmic loads. Seismic lateral earth pressures on restrained and unrestrained retaining waUs may be assumed to equal an inverted triangle starting at the bottom of the waU with the maximum pressure equal to 7H pounds per square foot (where H = waU height in feet) occurring at the top of the retained portion of the waU. WATERPROOFING AND SUBDRAIN: Waterproofing detaUs should be provided by the project architect. A su^ested waU subdrain detaU is provided on Plate No. 3. We recommend that the Geotechnical Consultant observe aU retaining waU subdrains to verify their installation. BACKFILL: AU backfiU soUs should be compacted to at least 90 percent relative compaction. Expansive or clayey soUs shoidd not be used for backfiU materiaL The waU should not be backfiUed until the masonry has reached an adequate strength. CWE 2110148.01 July 6,2011 PageNo. 16 LIMITATIONS REVIEW, OBSERVATION AND TESTING The recommendations presented in this report are contingent upon our review of final plans and specifications. Such plans and spedfications should be made avaUable to the (Jeotechidcal Engineer and Engmeering Geologist so that they may review and verify their compUance with this report and with the 2007 edition ofthe Califomia BuUding Code. It is recommended that Christian Wheder Engineering be retained to provide continuous soU engineering services during the earthwork operations. This is to verify compUance with the design concepts, specifications or recommendations and to aUow design changes in the event that subsurface conditions differ from those antidpated prior to start of constmction. 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 soU conditions encountered at the subsurface exploration locations and on the assumption that the soU conditions do not deviate appreciably from those encountered. It shoidd be recognized that the performance of the foundations and/or cut and fiU slopes may be influenced by undisdosed or unforeseen variations in the soU conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site devdopment should be brought to the attention of the (jeotechnical Engmeer 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. It should be verified in writing if the recommendations are found to be appropriate for the proposed changes or our recommendations should be modified by a written addendum. CWE 2110148.01 July 6,2011 PageNo. 17 TIME LIMITATIONS The findings of this report are vaUd 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 Govemment Codes may occur. Due to such changes, the findings of this report may be invaUdated whoUy or in part by changes beyond our controL Therefore, this report should not be reUed upon after a period of two years without a review by us verifying the suitabiUty of the condusions and recommendations. PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skUl ordinarily exerdsed by members of our profession currentiy practicing under similar conditions and in the same locaUty. The dient recognizes that subsurface conditions may vary from those encountered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations, and recommendations are based soldy on the information obtained by us. We wiU be responsible for those data, mterpretations, and recommendations, but shaU not be responsible for the kitetpretations by others of the information devdoped. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, express or impUed, 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. CUENT'S RESPONSIBIUTY It is the responsibUity of the CUent, or their representatives, to ensure that the information and recommendations contained herein are brought to the attention ofthe stmctural engineer and architect for the project and incorporated into the project's plans and specifications. It is fiirther thek responsibUity to take the necessary measures to insure that the contractor and aU subcontractors carry out such recommendations during constmction. Existing Grade 4' Typical Bench Hdgjit Competent Earth Material Provide heel drain during gradeing as required per recommendations of soils engineer. Drain sloped at minimum of 1% toward and a suitable outlet Competent Earth Material Where natural slope gradient is 5:1 or less, benching is not necessary. However, all compressible or unsuitable materials are to be removed prior to placing fill material. NO SCALE FIU SLOPE ABOVE CUT SLOPE DETAIL KIRGIS SUBDtVISION CAKLSBAD TRACT 02.M TWAIN AVENUE CARLSBAD, GALIFORlvHA w CHRJSTIAN WHEELER ENGINEERING FIU SLOPE ABOVE CUT SLOPE DETAIL DATE; July 6,2011 JOBNO.: 2110148.01 w CHRJSTIAN WHEELER ENGINEERING FIU SLOPE ABOVE CUT SLOPE DETAIL BY: JDB PLATE NO.: 2 w CHRJSTIAN WHEELER ENGINEERING 3/4 inch Crushed Rock or Miradrain 6000 or Equivalent Geofabric Between. Rock and Soil ' 12" L E 6-inch Minimum Waterproof Back of WaU Per Architect's Specifications Top of Ground or Concrete Slab Minimum 4-inch Diameter Perforated Pipe PVC Schedule 40 T 6-inch Minimum RETAINING WALL SUBDRAIN DETAIL No Scale CHRISTIAN WHEELER ENGINEERING KIRGIS SUBDIVISION CARLSBAD TRACT 024)6 TWAIN AVENUE, CARLSBAD, CAUFORNIA CHRISTIAN WHEELER ENGINEERING BY: MAH DATE: July 6,2011 3980 HOME AVENUE SAN DIEGO, CALIFORNIA 92105 TEL. (619) 550-1700 FAX. (619) 550-1701 JOB NO.: 2110148.01 PLATE NO.: 3 Appendix A Data from CWE 201.116 Geotechnical Report t - Date Excavated: Equipment: Existing Elevation: LOG OF TEST TRENCH NUMBER T-l 2/15/01 Logged by: DRR Backhoe Project Manager: CHC 313 feet Depth to Water: N/A Proposed Elevation: 328 feet Bucket Size: 24 inches a D 0 o l-l u S i SUMMARY OF SUBSURFACE CONDITIONS SAMPLES is C/J t-H o u P - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 10 Topsoil: Dark brown, SILTY SAND (SM), moist, loose, fine- to medium- grained. Subsoil; Medium brown, CLAYEY SAND (SC), moist, loose to medium dense, fine- to medium-grained. • I in IS Terrace Deposits (Ot): Orangish-brown, CLAYEY SAND (SC), moist, dense, fine- to coarse-grained. CK 7.3 CK 6.4 111.1 115.5 SA El MD DS Terminated at 8 feet. CHRISTIAN WHEELER. ENCINEER.ING PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, Califomia BY: SCC |OB NO. 201.116 DATE: February 27, 2001 PLATE NO.: LOG OF TEST TRENCH NUMBER T-2 Date Excavated: 2/15/01 Lo^edby: DRR Equipment: Backhoe Project Manager: CHC Existing Elevation: 325 feet Depth to Water: N/A Proposed Elevation: 328 feet Bucket Size: 24 inches C3 SUMMARY OF SUBSURFACE CONDITIONS SAMPLES o 2 u fc P SB Topsoil: Dark brown, SILTY SAND (SM), moist, loose, fine- to medium- grained. - 2 - 4 - 5 - 7 - 8 - 9 10 Subsoil: Medium brown, CLAYEY S7\ND (SC), moist, loose to medium dense, fine- to medium-grained. Santiago Formation (Tsa): Light brown, CLAYEY SAND (SC), moist, dense, fine- to medium-grained. CK Light brown to olive brown, S.ANDY CLAY (CL), moist, very hard. CK Terminated at 6 feet. 7.6 19.1 116.5 101.1 SA w CHRISTIAN WHEELER ENG1NEER.ING PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, Califomia BY: SCC IOB NO.: 201.116 DATE: February 27, 2001 PLATE NO.: LOG OF TEST TRENCH NUMBER T-3 Date Excavated: Equipment: Existing Elevation: 2/15/01 Backhoe 317 feet Lo^d by: DRR Project Manager: CHC Depth to Water: N/A Proposed Elevation: 314 feet Bucket Size: 24 inches SUMMARY OF SUBSURFACE CONDITIONS SAMPLES tLl O C/3 HH Q u fc p o :S ft PQ - 1 - 2 - 3 - 4 Topsoil: Dark brown, SILTY SAND (SM), moist, loose, fine- to medium- grained. Subsoil: Medium brown, CLAYEY SAND (SC), moist, loose to medium dense, fine- to medium-grained. Terrace Deposits (Ot): Orangish-brown, CLAYEY SAND (SC), moist, dense to very dense, fine- to coarse-grained with occasional 3 inch cobble. CK - 6 - 8 - 9 Sanriaeo Formation (Tsa): Light brown to white, SILTY SAND (SM), moist, dense to very dense, fine- to medium-grained. CK 11.0 111.9 Terminated at 10 feet. CHRISTIAN WHEELER ENGINEER.1NG PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, Califomia BY: SCC IOB NO. 201.116 DATE: February 27,2001 PLATE NO.: LOG OF TEST TRENCH NUMBER T-4 Date Excavated: 2/15/01 Logged by: DRR Equipment: Backhoe Project Manager: CHC Existing Elevation: 317 feet Depth to Water: N/A Proposed Elevation: 314 feet Bucket Size: 24 inches P O u s 0 SUMMARY OF SUBSURFACE CONDITIONS SAMPLES z I p 2 o z ^ H o c/3 l-H o fc p is T MP) -1 m Topsoil: Dark brown, SILTY SAND (SM), moist, loose, fine- to medium- grained. - 2 - 4 - 6 - 7 - 8 - 9 I- 10 Subsoil: Medium brown, CLAYEY SAND (SC), moist, loose to medium dense, fine- to medium-grained. Terrace Deposits (Ot): Orangish-brown, CLAYEY SAND/SILTY SAND (SC/SM), moist, dense to very dense, occasional gravel and cobble. CK Terminated at 7 feet. CHRISTIAN WHEELER ENGINEER.1NG PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, Califomia BY: SCC TOB NO.: 201.116 DATE: February 27, 2001 PLATE NO.: LOG OF TEST TRENCH NUMBER T-5 Date Excavated: 2/15/01 Logged by: DRR Equipment: Backhoe Project Manager: CHC Existing Elevation: 290 feet Depth to Water: N/A Proposed Elevation: 306 feet Bucket Size: 24 inches PH P SUMMARY OF SUBSURFACE CONDITIONS SAMPLES z u Q P P *S c/3 SB - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 1- 10 Hi t Topsoil: Dark brown, SILTY SAND (SM), moist, loose, fine- to medium- grained. 4^ A I Ml Slopewash (Osw): Dark brown, S.ANDY CLAY (CL), wet, soft, slight amount of gravel and cobble. Sanriapn Formation (Tsa): Light brown to light orangish-brown, CLAYEY S.AND (SC), moist, medium dense to dense. Becomes very dense. CK CK 11.2 114.3 Trench log continued on Plate 7. CHRISTIAN WHEELER ENGINEER.ING PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, Califorma BY: SCC JOB NO. 201.116 DATE: Febmary 27,2001 PLATE NO.: Date Excavated: Equipment: Existing Elevation: Proposed Elevation: LOG OF TEST TRENCH NUMBER T-5 (Continued) 2/15/01 Lo^d by: DRR Backhoe Project Manager: CHC 290 feet Depth to Water: N/A 306 feet Bucket Size: 24 inches W P SUMMARY OF SUBSURFACE CONDITIONS SAMPLES z ^ c I P 2 < o z % [i] o CO o u fc P ^ ft - 11 12 - 13 - 14 15 - 16 - 17 18 - 19 I- 20 m sr. i. Santiago Formation (Tsa): Light brown to light orangish-brown, CLAYEY SAND (SC), moist, very dense. CK 15.5 113.2 Terminated at 15 feet. w PROPOSED 5-LOT RESIDENTIAL PROJECT w West of Faraday Road, Carlsbad, Califomia CHRISTIAN WHEELER BY: SCC DATE: February 27, 2001 ENGINEERING TOB NO.: 201.116 PLATE NO.: 7 Date Excavated: 2/15/01 Equipment: Backhoe Existing Elevation: 313 feet Proposed Elevation: 300/306 feet LOG OF TEST TRENCH NUMBER T-6 Lo^ed by: DRR Project Manager: CHC Deptii to Water: N/A Bucket Size: 24 inches PH a p o u E i SUMMARY OF SUBSURFACE CONDITIONS SAMPLES z ^ c I p 2 IS ° 11] o C/3 t-H s u fc p c/3 is -1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 ••It--la Topsoil: Dark brown, SILTY SAND (SM), moist, loose, fine- to medium- grained. Slopewash ^Osw;>: Dark brown, SANDY CLAY (CL), wet, soft, slight amount of gravel and cobble. Santiago Formation (Tsa): Light brown to light orangish-brown, S-ANDY CLAY (CL), moist, very stiff Becomes hard. CK 15.4 110.4 SA EI MD DS l_ 10 UBI 1 Trench log continued on Plate 9. w CHRISTIAN WHEELER ENGINEERING PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, Califomia w CHRISTIAN WHEELER ENGINEERING BY: SCC DATE: February 27, 2001 w CHRISTIAN WHEELER ENGINEERING IOB NO.: 201.116 PLATE NO.: 8 LOG OF TEST TRENCH NUMBER T-6 (Continued) Date Excavated: 2/15/01 Logged by: DRR Equipment: Backhoe Project Manager: CHC Existing Elevation: 313 feet Depth to Water: N/A Proposed Elevation: 300/306 feet Bucket Size: 24 inches PH a p - 15 - 16 - 17 - 18 - 19 I- 20 o l-l u S PH SUMMARY OF SUBSURFACE CONDITIONS Santiago Formation (Tsa): Light brown to light orangish-brown, SANDY CLAY (CL), moist, hard. Terminated at 14 feet. SAMPLES CK z ^ < o Z P tn O 1^ e o 18.0 fc fe P 108.6 fe :S ft is CHRISTIAN WHEELER ENGINEER.ING PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, California BY: SCC IOB NO.: 201.116 DATE: February 27, 2001 PLATE NO.: Date Excavated: Equipment: Existing Elevation: LOG OF TEST TRENCH NUMBER T-7 2/15/01 Lo^d by: DRR Backhoe Project Manager: CHC 275 feet Depth to Water: N/A Proposed Elevation: 315 feet Bucket Size: 24 inches 2 u E i 0 SUMMARY OF SUBSURFACE CONDITIONS SAMPLES rt z ^ p - §1 (1] o ^ 5. c/1 HH o u fc D fe P fe c/3 s - 3 - 4 - 5 - 6 • •• .* fr. i - 7 ' ! i Topsoil: Dark brown, SILTY SAND/CLAYEY SAND (SM/SC), moist, loose, fine- to medium-grained. Slopewash ^Osw^: Dark brown, SANDY CLAY (CL), wet, soft to medium stiff, slight amount of gravel and cobble. gj^ntiagn Formation fTsa^: Light oUve brown to light orangish-brown, CLAYEY SAND (SC), moist, dense to very dense, fine- to medium-grained. CK 16.3 CK 16.8 109.3 110.0 Practical refusal at 9 feet. PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, Califomia CHRISTIAN WHEELER BY: SCC DATE: February 27, 2001 ENGINEER.ING IOB NO.: 201.116 PLATE NO.: 10 LOG OF TEST TRENCH NUMBER T-8 Date Excavated: 2/15/01 Lo^d by: DRR Equipment: Backhoe Project Manager: CHC Existing Elevation: 314 feet Depdi to Water: N/A Proposed Elevation: 315 feet Bucket Size: 24 inches P o u E s SUMMARY OF SUBSURFACE CONDITIONS SAMPLES rt z U z ^ ll] O c/) t—t o u fc /? fe P fe c/3 ^s - 1 Topsoih Dark brown, SILTY SAND (SM), moist, loose, fine- to medium- grained. M 2 rv > 3 i\ It 4 h I .8 Subsoil; Medium brown, CLAYEY SAND (SC), moist, loose to medium dense, fine- to medium-grained. - 5 - fi ^ - 7 - 8 - 9 10 Terrace Deposits (Ot); Orangish-brown, CLAYEY SAND (SC), moist, dense to very dense, fine- to coarse-grained, occasional 2V2 inch gravel. CK CK 6.0 113.0 Tenninated at 7 feet. PROPOSED 5-LOT RESIDENTIAL PROJECT West of Faraday Road, Carlsbad, Califomia CHRISTIAN WHEELER BY: SCC DATE: February 27,2001 ENGINEER-ING IOB NO.: 201.116 PLATE NO.: 11 LOG OF TEST TRENCH NUMBER T-9 Date Excavated: 2/15/01 Lo^ed by: DRR Equipment: Backhoe Project Manager: CHC Existing Elevation: 314 feet Deptii to Water: N/A Proposed Elevation: - Bucket Size: 24 inches PH a P o o l-l u E i SUMMARY OF SUBSURFACE CONDITIONS SAMPLES w z ^ c I p 2 ^ o M \ z ^ ca o c/3 I—I o u fc Z P Pi p - 1 - 2 - 3 - 4 - 5 - 6 M Subsoil: Medium brown, CLAYEY S7\ND (SC), moist, loose to medium dense, fine- to medium-grained. - 7 - 9 i M i I- 10 Terrace Deposits fOt^: Orangish-brown, CLAYEY SAND (SC), moist, very dense, fine- to coarse-grained, abundant gravel and cobble. CK 5.7 Santiago Fotmarion fTsa^: Light olive brown, CLAYEY SAND (SC), moist, dense to very dense, fine- to medium-grained. CK 15.8 CK CKI 122.8 111.0 Terminated at 10 feet. w PROPOSED 5-LOT RESIDENTIAL PROJECT w West of Faraday Road, Carlsbad, Califomia CHRISTIAN WHEELER BY: SCC DATE: February 27, 2001 ENGINEER.ING IOB NO.: 201.116 PLATE NO.: 12 LABORATORY TEST RESULTS PROPOSED FIVE-LOT RESIDENTIAL PROTECT WEST QF FARADAY ROAD POWAY. CALIFORNLV MAXIMUM DENSITY/ OPTIMUM MOISTURE CONTENT Sample Nuniber Description Maximuni Density Optimum Moisture Content Trench T-l @2'-8' Orangish-brown, clayey sand (SC) 127.1 pcf 8.5 percent Trench T-6 @3'-12' Brown, sandy clay (CL) 106.0 pcf 18.5 pcf DIRECT SHEAR TEST Sample Number Description Angle of Internal Friction Apparent Cohesion Trench T-l @2'-8' Remolded To 90 Percent 33 degrees 100 psf Trench T-6 @3'-12' Remolded to 90 Percent 21 degrees 300 psf GRAIN SIZE DISTRIBUTION Sample Number T-l @ 2'-8' T-2 @ 4'-6' T-6 @ 3'-12' Sieve Size Percent Passing Percent Passing Percent Passing #4 100 #8 93 100 100 #15 78 99 699 #30 59 98 98 #50 37 97 96 #100 22 87 84 #200 19 70 69 0.05 mm 18 60 55 0.005 mm 11 27 21 0.001 mm 8 18 7 Classification SC CL CL EXPANSION INDEX TESTS Sample Number: Iiutial Moisture: Iiutial Dry Density: Final Moisture: Expansion Index: Trench T-8 @2'-8' 8.0 percent 108.3 pcf 17.7 percent 6 (very low) Trench T-6 @3'-l 2' 13.7 percent 101.4 pcf 29.5 percent 85 (medium) CWE 201.116.1 March 14,2001 Plate No. 13 SLOPE STABIUTY ANALYSIS - FILL SLOPES Propsed Five-Lot Residential Project West of Faraday Road Carlsbad. Califomia Five-Lot Project CWE 201,116 Ten Most Critical. Ai5LnTriLL.PLT By; SCC 03-12-01 li50pn 380 360 rs a a.29 to 2,30 c 2,31 d 2.32 e 2.32 f 2,33 . 9 2.35 h 2.35 i 2.36 J 2.36 340 Elev. (ft) 320 300 ,9 f Proposed 2:1 Slope Fill (Qaf) Terrace Deposits (Qt) Santiago Formation (Tsa) J' 20 40 60 80 100 STABL6H FSnln= =2,29 X-Axis (ft) Soil Total Saturated Cohesion Friction Pore Pressure Type Unit Wt, Unit Wt, Intercept Angle Pressure Constant No, Label <pcf> <pcf> (psf) (deg) Paran, (psf) 1 Tsa UO 130 500 28 0 0 2 Qt 115 135 200 35 0 0 3 nil 115 135 350 32 0 0 120 140 Piez, Surface No. CHRISTIAN WHEELER ENGINEERING Plate 14 SLOPE STABILITY ANALYSIS - CUT SLOPES Propsed Five-Lot Residential Project West of Faraday Road Carlsbad. Califomia Five-Lot Project CWE 201,116 Ten Most Critical AiSLDTCUT.PLT Byi SCC 03-12-01 l:56pn 33t> 310 # FS a 3.05 b 3,06 c 3,07 d 3.08 e 3,08 - f 3,09 g 3,10 h 3.11 i 3,14 J 3,14 Elev, (ft) 300- 29C- 28C- 27(> 0 Proposed 2:1 Slope Santiago Fomiation (Tsa) Soil Type No, Label 1 TSQ 30 40 50 60 STABL6H FSnin=3.05 X-Axis (ft) Total Saturated Cohesion Friction Pore Unit Wt. Unit Wt. Intercept Angle Pressure (pcf) (pcf) (psf) (deg) Poran, 110 130 500 28 0 Pressure Constant (psf) 0 80 Piez. Surface No, 90 CHRISTIAN WHEELER ENGINEERING Plate 15 Appendix B References CWE 2110148.01 July 6,2011 Appendbc B, Page B-l REFERENCES Uiuted Stated Geologic Survey, Seismic Design Values for Buildings, Java Ground Motion Calculator Version 5.1.0. Appendix C Recommended Grading Specifications - General Provisions CWE 2110148.01 July 6,2011 Appendix C, Page C-1 RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS KIRGIS SUBDIVISION CJMILSBAD TRACT 02-06 TWAIN AVENUE CARLSBAD. CALIFORNIA GENERAL INTENT 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 written communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian Wheeler Engineering shall be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer or his representative provide adequate observation so that he may provide his opiiuon as to whether or not the work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geotechnical Engineer and to keep him apprised of work schedules, changes and new infonnation and data so that he may provide these opiiuons. 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 fiirther recommendations. If, in the opiiuon of the Geotechnical Engineer, substandard conditions are encountered, 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. CWE 2110148.01 July 6,2011 Appendix C, Page C-2 Tests used to determine the degree of compaction should be performed in accordance with the following American Society for Testing and Materials test methods: Maximum Density & Optimum Moisture Content - ASTM D-1557 Density of Soil In-Place - ASTM D-1556 or ASTM D-6938 All densities shall be expressed in terms of Relative Compaction as detemiined 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 appearance, free from unsightiy 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. When tiie slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to 1 vertical unit), the original grovmd 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 widtii, whichever is greater, and shall be sloped back into the hillside at a gradient of not less than two (2) percent M 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 tiian 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 undergroimd utilities to be abandoned beneath any proposed stmcture 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 die 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 tiiat 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 tiie Geotechnical Engineer. The top of the cap should be at least 4 feet below finish grade or 3 CWE 2110148.01 July 6, 2011 Appendix C, Page C-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 Stmctural 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 defiiution 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 mked with otiier soils to provide satisfactory fill material, but only with the explicit consent of tiie 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 efficientiy 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 size 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. When the stmctural fill material includes rocks, no rocks will be allowed to nest and all voids must be carefully filled with soil such tiiat 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 fills is discussed in the geotechnical report, when applicable. Field observation and compaction tests to estimate tiie degree of compaction of the fill will be taken by the Geotechnical Engineer or his representative. The location and frequency of die tests shall be at the Geotechnical 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 reworked to the satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. CWE 2110148.01 July 6, 2011 Appendix C, Page C-4 Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment Compaction 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 trackroUed. Steeper fill slopes shall be over-built and cut- back to finish contours after the slope has been constmcted. 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 section of this specification. The compaction operation on the slopes shall be 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 die slopes to determine if the required compaction is being achieved. Where failing tests occur or other field problems arise, the Contractor will be notified tiiat 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 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 tiie Engineering Geologist and Geotechnical Engineer to determine if mitigating measures 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 govemmental agency. ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shall be made during the filling and compaction operations so tiiat he can express his opinion regarding die conformance of the grading with acceptable standards of practice. Neither tiie presence of die Geotechnical Engineer or his representative or CWE 2110148.01 July 6, 2011 Appendix C, Page C-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 UMITS Fill shall not be placed during unfavorable weather conditions. When work is intermpted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill niaterials 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 ASTM D 4829. OVERSIZED MATERIAL: Oversized fill material is generaUy defined herein as rocks or lumps of soil over 6 inches in diameter. Oversized niaterials should not be placed in fiU unless recommendations of placement of such material is provided by the Geotechnical Engineer. At least 40 percent of the fiU soils shaU pass through a No. 4 U.S. Standard Sieve. TRANSITION LOTS: Where transitions between cut and fiU occur within die proposed building pad, tiie cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as stmctural backfiU. 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.