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CT 05-18; Seascape; PRELIMINARY GEOTECHNICAL INVESTIGATION; 2004-09-29
PRELIMINARY GEOTECHNICAL INVESTIGATION, PROPOSED RESIDENTIAL SUBDIVISION, NORTHEAST OF AVENA COURT AND BLACK RAIL ROAD, APN'S 21504009 AND 21504011, CARLSBAD, CALIFORNIA Prepared For: Nobel Homes 2734 Loker Ave. West, Suite M Carlsbad, California 92008 Project No. 041265-001 September 29, 2004 Leighton and Associates, Inc. A LEIGHTON GROUP COMPANY Leighton and Associates, Inc. A LEIGHTON GROUP COMPANY September 29, 2004 To: Attention: Nobel Homes 2734 Loker Ave. West, Suite M Carlsbad, California 92008 Ms. Jennifer Benner Project No. 041265-001 Subject: Preliminary Geotechnical Investigation, Proposed Residential Subdivision, Northeast of Avena Court and Black Rail Road, APN's 21504009 and 21504011 , Carlsbad, California In accordance with your request and authorization, we have conducted a preliminary geotechnical investigation of the proposed residential development located northeast of the intersection of A vena Court and Black Rail Road in Carlsbad, California. Based on the results of our geotechnical study, it is our professional opinion that the site is suitable to receive the proposed improvements. The accompanying report presents a summary of the existing conditions of the site, the results of our field investigation and laboratory testing, and provides geotechnical conclusions and recommendations relative to the proposed site development. If you have any questions regarding our report, please contact this office. We appreciate this opportunity to be of service. Respectfully submitted, LEIGHTON AND AS SOCIA TES,JN.C 6~t~ f.SS I OJV~ M(JU)J!--[~~ . /:}/~ <P..·~ ~ ~--No. 45283 ~ \ ~ -S: o/~ .-l . .., William D. Olson, RCE\ ~ 3 Exp.~ f ~ 1 Senior Project Engineer \\ ·~r r;\ . / Jf-/ '\ 0/' ', Ctv\\.. .<'~ '/ " ;/·.:·-. :-~-,,' . ~ .. < ..... : ,} . c \\_\ ~ Distribution: ( 1 0) Addressee -<::-------:::·;::.::;;:;, Michael R. Stewart, CEG 1349 Principal GeologistNice President 3934 Murphy Canyon Road, Suite 8205 • San Diego, CA 92123-4425 858.292.8030 • Fax 858.292.0771 • www.leightongeo.com 041265-001 TABLE OF CONTENTS Section 1.0 INTRODUCTION ........................................................................................................... 1 1.1 SCOPE OF WORK ...................................................................................................... 1 1.2 SITE DESCRIPTION AND PROPOSED DEVELOPMENT ............................................................. 1 2.0 SUBSURFACE EXPLORATION AND LABORATORY TESTING 4 3.0 SUMMARY OF GEOTECHNICAL CONDffiONS .................................................................. 5 3.1 REGIONAL GEOLOGY ................................................................................................. 5 3.2 SITE GEOLOGY ......................................................................................................... 5 3.2.1 Artificial Fill-undocumented (Map Symbol-Afu) ................................................ 5 3.2.2 Topsoil (Unmapped) ........................................................................................... 5 3.2.3 Slopewash Deposits (Map Symbol Qsw) ................................................................ 6 3.2.4 Terrace Deposits (Map Symbol-Qt) ..................................................................... 6 3.3 GEOLOGIC STRUCTURE ............................................................................................... 6 3.4 lANDSLIDING ........................................................................................................... 6 3.5 SURFACE AND GROUND WATER .................................................................................... 7 3.6 FAULTING .............................................................................................................. 7 3.6.1 CBC Seismic Design Criteria ................................................................................ 7 3.7 SECONDARY SEISMIC HAZARDS .................................................................................... 8 3.7.1 Shallow Ground Rupture ..................................................................................... 8 3.7.2 Liquefaction and Dynamic Settlement .................................................................. 8 3.8 ENGINEERING CHARACTERISTICS OF THE ON-SITE SOILS .................••.......•.•..••••••............... 8 3.8.1 Expansion Potential ............................................................................................ 8 3.8.2 Soil Corrosivity ................................................................................................... 9 4.0 CONCLUSIONS .......................................................................................................... 10 5.0 RECOMMENDATIONS ................................................................................................. 11 5.1 EARTHWORK ......................................................................................................... 11 5.1.1 Clearing and Site Preparation ............................................................................ 11 5.1.2 Removal and Recompaction .............................................................................. 11 5.1.3 Excavations and Oversize Material ..................................................................... 12 5.1.4 Fill Placement and Compaction .......................................................................... 12 5.1.5 Transition Lots ................................................................................................. 13 5.2 FOUNDATION DESIGN CONSIDERATIONS ...............•••...•.•.•••....••••••......•••••...•...••••...••...... 13 5.2.1 Conventionally-Reinforced Foundations ............................................................... 13 5.2.2 Moisture Conditioning of Foundation Subgrade Soils ............................................. 15 5.2.3 Foundation Setback from Slopes ........................................................................ 15 5.2.4 Preliminary Floor Slab Design ............................................................................ 15 5.2.5 Settlement ...................................................................................................... 16 5.3 LATERAL EARTH PRESSURES ...................................................................................... 16 5.4 GEOCHEMICAL CONSIDERATIONS ................................................................................ 17 Leighton 041265-001 TABLE OF CONTENTS Section 5.5 SLOPE STABILITY .................................................................................................... 17 5.6 PRELIMINARY PAVEMENT DESIGN ................................................................................ 18 5.7 CONTROL OF SURFACE WATER AND DRAINAGE ................................................................ 19 5.8 SLOPE MAINTENANCE GUIDELINES ..••.........................•.•••....••...•..•...........•..••.••••.••........ 20 5.9 lANDSCAPING AND POST-CONSTRUCTION ...................................................................... 20 5.10 CONSTRUCTION OBSERVATION AND TESTING .................................................................. 21 6.0 LIMITATIONS ............................................................................................................ 22 Tables Table 1-Minimum Foundation and Slab Design Recommendations-Page 14 Table 2 -Minimum Foundation Setback from Slope Faces -Page 15 Table 3 -Static Equivalent Fluid Weight (pcf) -Page 16 Table 4 -Preliminary Pavement Section Designs -Page 18 Figure 1 -Site Location Map -Page 3 Plate 1 -Geotechnical Map -In Pocket Appendices Appendix A -References Appendix B -Trench Logs Appendix C -Laboratory Testing Procedures and Results Appendix D -General Earthwork and Grading Specifications and Retaining Wall Detail ii Leighton 041265-001 1.0 INTRODUCITON 1.1 Scope of Work This report presents the results of our preliminary geotechnical investigation for the proposed residential subdivision adjacent to Black Rail Road (APN's 21504009 and 21504011) in Carlsbad, California (Figure 1). The purpose of our investigation was to identify and evaluate the existing geotechnical conditions present at the site and to provide preliminary conclusions and geoteclmical recommendations relative to the proposed development. Our scope of services included: • • • • • • Review of available pertinent, published and unpublished geotechnical literature and maps. A list of references is provided in Appendix A of this report. Field reconnaissance of the existing onsite geotechnical conditions . Subsurface exploration performed as part of this study included 8 exploratory trenches in the vicinity of the proposed improvements using a backhoe. The logs of all the trenches are presented in Appendix B, and the locations are presented on the Geotechnical Map (Plate 1 ). Limited laboratory testing of representative soil samples obtained from the subsurface exploration program which included maximum density, expansion potential and sulfate content. Results of these tests are presented in Appendix C, and are noted on the logs where appropriate. Compilation and analysis of the geotechnical data obtained from the field investigation and laboratory testing. Preparation of this report presenting our findings, conclusions, and geotechnical recommendations with respect to the proposed design, site grading, and general construction considerations. 1.2 Site Description and Proposed Development The site is located northeast of the intersection of Black Rail Road and A vena Court in the City of Carlsbad, California (Figure 1). The rectangular shaped site is bounded by existing residential development to the north, Black Rail Road to the west, A vena Court (east) to the south, and open space to the east. The site slopes gently to the east and elevations range from approximately 338 to 358 feet (mean sea level). A majority of the site is presently being utilized as a nursery, with a series of greenhouses situated across the site. A major overhead utility easement crosses the site diagonally. -1-Leighton 041265-001 Based on the site plan provided (CIVCOM, 2004), the development will consist of a 13-lot residential development. The residential structures are anticipated to be one-to two-story in height with conventional foundations, wood-frame wall, and stucco exteriors. Associated improvements are anticipated to including underground utilities, landscaping, hardscaping, driveways and retaining wall structures. Access to the site will be from A vena Court (east) to the south, via proposed paved roads, identified as Street "A" and Surf Crest Street. Site grading will include cuts and fills , generally on the order of 5 to 10 feet in order to establish the finish grades for the proposed lots and associated streets. No structures are proposed within the overhead utility easement. -2-Leighton LN NORTH CORTE ~ ORCHIDIA DOCENA ;--~:.::.:.:.:...:..,_- BASE MAP: 2003 Digital Edition Thomas Guide, San Diego County Nobel Homes at Black Rail Road Carlsbad , California SITE LOCATION MAP PROJECT SITE NOT TO SCALE Project No. 041265-001 Date September 2004 Figure No.1 041265-001 2.0 SUBSURFACE EXPLORATION AND LABORATORY TESTING Subsurface exploration was performed on August 3, 2004. Our subsurface exploration consisted of the excavation, logging, and sampling of eight (8) exploratory trenches within the proposed site using a backhoe. The trenches were excavated to approximate depths of 3 to 14 feet bgs (below ground surface). The purpose of these excavations was to evaluate the physical characteristics and engineering properties of the onsite soils pertinent to the proposed development. The excavations allowed evaluation of the soils encountered at anticipated foundation elevations in proposed cut areas, the general nature of the soils proposed for use as compacted fills, and provided representative samples for laboratory testing. We note that a majority of the site was covered by greenhouses at the time of our investigation and the area available to be investigated was limited. As a result, some localized variations may be encountered across the site during site grading. The exploratory trench excavations were logged by a geologist from Leighton. Representative samples were obtained at appropriate intervals for laboratory testing. The approximate locations of the explorations are shown on the Geotechnical Map (Plate 1 ). After logging and sampling, the excavations were backfilled. Laboratory te sting was performed on representative samples to evaluate the compaction characteristics (m aximum dry density and optimum moisture content), soluble sulfate content, and expansion potential. A discussion of the laboratory tests performed and a summary of the laboratory test res ults are presented in Appendix C. -4-Leighton 041265-001 3.0 SUMMARY OF GEOTECHNICAL CONDmONS 3.1 Regional Geology The project is situated in the coastal section of the California Peninsular Range, a geomorphic province with a long and active geologic history. This region is more specifically known as the San Diego Embayment, an area that has undergone several episodes of marine inundation and regression during the last 54 million years. This has left a thick sequence of marine and non-marine sediments overlying the Southern California batholith. Recent topographic uplifts have lead to the erosion of these creating the canyon and ridgelines seen today. 3.2 Site Geology Based on our site visit and review of pertinent geologic and geotechnical literature (Appendix A), the subject site is underlain by surficial soils including undocumented fill soils, topsoil, slopewash, and formational materials consisting of Quaternary-aged Terrace deposits. The approximate limits of the geologic units are presented on the Geotechnical Map (Plate 1). A description of the geologic units present on the site is presented below. 3.2.1 Artificial Fill -undocumented (Map Symbol -Afu) Artificial fill soils apparently placed during the site's initial construction and/or previous site uses were observed in various areas across the site. It is assumed that no engineering observation of these fill soils was provided at the time of their placement. These fill soils were found to generally consist of very loose to medium dense, silty sand and gravel. As ecnountered in our trenches, these soils were up to 12 feet in depth and are expected to be thickest along the eastern side of the site. Areas of deeper fill soils may exist on site in localized areas. Complete removal of these materials is recommended in the areas of the proposed development. 3.2.2 Topsoil (Unmapped) A relatively thin veneer of topsoil was observed at the surface in localized areas of the site. The topsoil, as observed, consists predominantly of brown, damp to -5-Leighton 041265-001 moist, loose, silty, fine to medium sand. These soils were generally porous, and contained scattered roots and organics. Topsoil thickness was on the order of 1 foot at the trench locations. Localized deeper areas of topsoil may be encountered in areas not investigated. 3.2.3 Slopewash Deposits (Map Symbol Qsw) Quaternary-Aged Slopewash deposits were encountered underlying the artificial fill soils in the eastern portion of the site. The map unit generally consists of dry, loose, weathered silt and fine sands, approximately 2 to 5 feet in thickness. In general, it compromises the highly-weathered surifical soils developed on the underlying terrace deposits. Removal and recompaction of these materials is recommended in the area of the proposed improvements. 3.2.4 Terrace Deposits (Map Symbol-Qt) The Quaternary-aged Terrace deposits were exposed at grade in the western portion of the site and at depth beneath the surficial deposits to the east of the site. This unit generally consists of orange brown to red brown, damp, medium dense to dense, silty, fine to medium grained sand. This material typically is friable to moderately indurated and has a very low to low expansion potential. The terrace deposits overlie bedrock materials of the Santiago Formation. Although not encountered during our investigation, is expected at an approximate elevation of 325 foot (msl) in the site vicinity (Tan and Kennedy, 1996), 15 to 30 feet below the existing site grades. 3.3 Geologic Structure Based on our experience on projects in the area, bedding on the site is generally massive with no well-defined structure. Regional dips in the area are generally flat lying to slightly dipping to the west. 3.4 Landsliding No ancient landslides have been mapped on the site and no evidence of landsliding was observed during our site investigation. -6-Leighton 041265-001 3.5 Surface and Ground Water No indication of surface water or evidence of surface ponding was encountered during our field investigation. However, surface water may drain as sheet flow in the higher portions of the site during rainy periods and accumulate in lower portions of the site. Geologic mapping should be performed during site grading to evaluate the subsurface conditions and need for possible subdrainage systems. 3.6 Faulting Our discussion of faults on the site is prefaced with a di scussion of California legislation and policies concerning the classification and land-use criteria associated with faults. By definition of the California Mining and Geology Board, an active fault is a fault that has had surface displacement within Holocene time (about the last 11 ,000 years). The state geologist has defined a potentially active fault as any fault considered to have been active during Quaternary time (last 1,600,000 years). This definition is used in delineating Earthquake Fault Zones as mandated by the Alquist-Priolo Earthquake Fault Zoning Act and as subsequently revised in 1997. The intent of this act is to assure that unwise urban development and certain habitable structures do not occur across the traces of active faults. The subject site is not included within any Earthquake Fault Zones as created by the Alquist-Priolo Act (Hart, 1997). Our review of available geologic literature (Appendix A) indicates that there are no known major or active faults on or in the immediate vicinity of the site. The nearest known active regional fault is the Rose Canyon Fault Zone located approximately 5.2 miles (8.3 kilometers) west of the site. 3.6.1 CBC Seismic Design Criteria The effect of seismic shaking may be mitigated by adhering to the California Building Code and state-of-the-art seismic design parameters of the Structural Engineers Association of California. The site is located within Seismic Zone 4 as designated by the California Building Code (CBSC, 2001 , Figure 16A-2). The soil profile designation for the site is considered to be type So per the 2001 CBC, Table 16A-J. Near source factors Na and Nv for the site equal to 1.0 and 1.0, respectively, are appropriate based on the seismic setting and criteria of Tables 16A-S and 16A-T of the 2001 CBC . -7-Leighton 041265-001 3. 7 Secondary Seismic Hazards Secondary effects that can be associated with severe ground shaking following a relatively large earthquake include shallow ground rupture, soil liquefaction and dynamic settlement, seismic slope instability seiches and tsunamis. These secondary effects of seismic shaking are discussed in the following sections. 3.7.1 Shallow Ground Rupture Ground rupture because of active faulting is not likely to occur on site due to the absence of known active faults. Cracking due to shaking from distant seismic events is not considered a significant hazard, although it is a possibility at any site. 3.7.2 Liquefaction and Dynamic Settlement Liquefaction and dynamic settlement of soils can be caused by strong vibratory motion due to earthquakes. Both research and historical data indicate that loose, saturated, granular soils are susceptible to liquefaction and dynamic settlement. Liquefaction is typified by a loss of shear strength in the affected soil layer, thereby causing the soil to liquefy. This effect may be manifested by excessive settlements and sand boils at the ground surface. The Quaternary Terrace deposits underlying the site are not considered liquefiable due to their physical characteristics, lack of an elevated ground water table, high- density characteristics, and age. 3.8 Engineering Characteristics of the On-site Soils Based on the results of our geotechnical investigation of the site, laboratory testing of representative on-site soils, and our professional experience on near-by sites with similar soils, the engineering characteristics of the on-site soils are discussed below. 3.8.1 Expansion Potential The majority of the onsite soils are expected to have a very low to low expansion potential (per UBC criteria). However, the actual expansion potential of finish grade soils should be determined upon completion of the grading. -8-Leighton 041265-001 3.8.2 Soil Corrosivity Based upon the 2001 CBC, Table 19A-A-4, laboratory test results on a selected soil sample collected during our field investigation indicate a negligible soluble sulfate exposure. Based on previous testing at other sites in the vicinity of this project, test results typically indicate a neutral pH, a positive chloride content, and moderate soil resistivity. Laboratory testing should be performed on the soils placed at or near finish grade after completion of site grading to confirm the actual geochemical properties. -9-Leighton 041265-001 4.0 CONCLUSIONS Based on the results of our preliminary geotechnical investigation of the site, it is our professional opinion that the proposed development is feasible from a geotechnical standpoint, provided the following conclusions and recommendations are incorporated into the project plans and specifications and utilized during the grading and construction phases of site development. The following is a summary of the significant geotechnical factors that we expect may affect development of the site. • Based on our subsurface exploration and review of pertinent geotechnical reports, the site is underlain by undocumented artificial fill soils, slopewash, and Quaternary-aged terrace deposits that is considered compressible and unsuitable for supporting structural loads or additional fill. The approximate limits of these units are presented on the Geotechnical Map (Plate 1 ). • The existing on-site soils appear to be suitable material for use as fill provided they are free of organic material and debris. • Ground water was not encountered during our investigation. • Laboratory testing of representative samples of the onsite soils indicates that the on-site soils possess a very low expansion potential per UBC criteria. However. low to moderately expansive soil may be present in topsoil and other localized areas but is anticipated to be limited in extent. • Laboratory test results indicate the onsite soil materials have a negligible potential for sulfate attack on concrete. Additional geochemical testing should be performed on soils placed at or near finish grade after completion of grading. • It is anticipated that the near surface materials may be excavated with conventional heavy-duty construction equipment. • Site grading may result in transition (cut/fill) lots that will require overexcavation of the cut portion to minimize potential differential settlements. • Active faults are not known to exist on or in the immediate vicinity of the site. The main seismic hazard affect the site is from grotmd shaking from one of the active regional faults. • Due to the relatively dense characteristics of the onsite formation materials and the lack of a ground water table, the potential for liquefaction is considered low. -10-Leighton 041265-001 5.0 RECOMMENDATIONS 5.1 Earthwork We anticipate that earthwork at the site will consist of site preparation, excavation, and fill placement operations. We recommend that earthwork on the site be performed in accordance with the City of Carlsbad grading requirements, the following recommendations and the General Earthwork and Grading Specifications for Rough Grading included in Appendix D. In case of conflict, the following recommendations shall supersede those presented in Appendix D. 5.1.1 Clearing and Site Preparation Prior to grading, all areas to receive structural fi ll , engineered structures or hardscape improvements should be cleared of surface and subsurface obstructions, including any existing debris, stockpiled material, loose soils as described in the following section, and stripped of vegetation. Removed vegetation and debris should be properly disposed off site. All areas to receive fill and/or other surface improvements should be scarified to a minimum depth of 6 inches, brought to near-optimum moisture conditions, and recompacted to at least 90 percent relative compaction based on ASTM Test Method D1557. 5.1.2 Removal and Recompaction As discussed above, portions of the site are underlain by potentially compressible soils that may settle under the surcharge of fill and/or fotmdation loads. Compressible materials not removed by the planned grading should be removed to competent material, moisture conditioned or dried back (as needed) to obtain a near optimum moisture content, and replaced as compacted fill prior to placement of additional fill or construction of improvements. Estimated removal depths of the beneath the proposed eastern lots (Lots 12 and 13) will likely extend to depths of 10 to 12 feet, but are expected to be shallower in the western areas of the site. Laterally, the removals should extend down and out beyond the propsed toe of slope to provide for a 1:1 horizontal to vertical projection. The actual depth and extent of the required removals should be determined during grading operations by the geotechnical consultant. The removal bottom should then be scarified a minimum of 6 inches, moisture conditioned and compacted to at least 90 percent relative compaction (based on ASTM Test Method D1557). -11-Leighton 041265-001 5.1.3 Excavations and Oversize Material Excavations of the onsite materials may generally be accomplished with conventional heavy-duty earthwork equipment. All excavations should be made in accordance with the current OSHA requirements. We do not anticipate that oversize material (i.e. rock fragments greater than 8 inches in maximum dimension) may be generated during excavation of the surficial and alluvial soils. However, recommendations for treatment of oversize material are included in the attached General Earthwork and Grading Specifications for Rough Grading (Appendix D). In addition, oversize material may be utilized in approved surface applications or hauled off site. 5.1.4 Fill Placement and Compaction The onsite existing soils are generally suitable for use as compacted fill provided they are free of organic material, debris, and rock fragments larger than 8 inches in maximum dimension. All fill soils should be brought to near-optimum moisture conditions and compacted in uniform lifts to at least 90 percent relative compaction based on laboratory standard ASTM Test Method Dl557. The upper 12 inches of suograde and all aggregate base should be compacted to at least 95 percent beneath vehicular pavements. The optimum lift thickness required to produce a uniformly compacted fill will depend on the type and size of compaction equipment used. In general, fill should be placed in lifts not exceeding 8 inches in thickness. The onsite soils may require moisture conditioning prior to use as compacted fill. Fills placed on slopes steeper than 5:1 (horizontal to vertical) should be keyed and benched into competent formational soils as indicated in the General Earthwork and Grading Specifications for Rough Grading presented in Appendix D. Placement and compaction of fill should be performed in general accordance with the current City of Carlsbad grading ordinances, sound construction practice, and the General Earthwork and Grading Specifications for Rough Grading presented in Appendix D. -12-Leighton 041265-001 5.1.5 Transition Lots Rough grading of the site may result in transition (cut/fill) lots. In order to reduce the potential for differential settlement in areas of transition or cut/fill lots, we recommend that cut/fill transition lots be overexcavated to a minimum depth of 5 feet below finish grade and replaced with properly compacted fill of very low to low expansion potential. This depth may be increased depending on adjacent fill depth. Additionally, overexavations should be graded to fall a minimum of 1 percent toward the front of the lot or deeper fill areas. The overexcavation and recompaction should laterally extend across the entire lot. 5.2 Foundation Design Considerations We understand the proposed residential structures will be one-to two-story, wood-frame construction utilizing a conventional slab-on-grade foundation system. Foundations and slabs should be designed by a structural engineer in accordance with appropriate building codes, structural considerations, and the following minimum recommendations. These recommendations assume that the soils in the upper 3 feet of finish grade wi ll have a very low to low expansion potential (an expansion index less than 50 per UBC 18-I-B). 5.2.1 Conventionally-Reinforced Foundations The proposed foundations and slabs of the single-family residential structures should be designed in accordance with appropriate building codes, structural considerations and the minimum recommendations contained on Table 1. -13-Leighton 041265-001 Table 1 Minimum Foundation and Slab Design Recommendations U.B.C. Expansion Index 0-50, Very Low to Low Expansion !-Story and 2-Story Footings All footings 18" deep. Reinforcement for continuous footings: two No.4 (Continuous) (See Note I) bars top and bottom. Isolated Spread Footings All footings 18" deep. Reinforcement per structural engineer. Any exterior pad footings should be connected by tie beams in two directions. Minimum Footing Width Continuous: 12" for !-story Continuous: 15" for 2-story Isolated spread (column) footings: 24" Garage Door Grade Bean1 A grade bean1 12" wide x 18" deep (See Note 2) should be provided across the garage entrance. Living Area Floor Slabs Minimum 5" thick slab. No.3 bars @ 18" or No.4 rebars@ 24" on (See Notes 3, 4 and 6) center each way at mid-height. 2" clean sand over I 0 mil moisture barrier over 2" clean sand. Garage Floor Slabs Minimum 5" thick concrete slab on 2" clean sand over I 0 mil moisture (See Notes 4, 5 and 6) barrier over 2" clean sand. No. 3 bars @ 18" or No. 4 rebars @24" on center each way at mid-height. Slab should be quarter-sawn. Presoaking of Living Area and Garage Normal slab subgrade wetting to a depth of6 inches. Slabs Allowable Bearing Capacity 2,000 pounds per square foot (one-third increase for short term loading) Notes: (I) Depth of interior or exterior footing to be measured from lowest adjacent ground surface excluding slabs and slab underlay mount. (2) The base of the grade beam should be at the same elevation as that ofthe adjoining footings. (3) Living area slabs should be tied to the footings as directed by the stmctural engineer. (4) 10-mil Vi squeen sheeting is acceptable. Equivalents are acceptable. All laps and penetrations should be sealed. (5) Garage slabs should be isolated from stem wall footings with a minimum 3/8" felt expansion joint. (6) Sand base should have a Sand Equivalent of30 or greater (e.g. washed concrete sand). -14-Leighton 041265-001 5.2.2 Moisture Conditioning of Foundation Subgrade Soils The slab subgrade soils underlying the foundations should be normally wetted to a minimum depth of 6 inches prior to the placement of the moisture barrier and slab concrete. The subgrade soil moisture content should be checked by a representative of Leighton and Associates prior to slab construction. 5.2.3 Foundation Setback from Slopes We recommend a minimum horizontal setback distance from the face of slopes for all structural foundations, footings, and other settlement-sensitive structures as indicated on Table 2. This distance is measured from the outside bottom edge of the footing, horizontally to the slope face and is based on the slope height and type of soil. However, the foundation setback distance may be revised by the geotechnical consultant on a case-by-case basis if the geotechnical conditions are different than anticipated. Table 2 Minimum Foundation Setback from Slope Faces Slope Height Minimum Recommended Foundation Setback less than 5 feet 7 feet greater than 5 feet I 0 feet Please note that the soils within the structural setback area possess poor lateral stability, and improvements (such as retaining walls, sidewalks, fences, pavements, etc.) constmcted within this setback area may be subject to lateral movement and/or differential settlement. Potential distress to such improvements may be mitigated by providing a deepened footing or a pier and grade beam foundation system to support the improvement. The deepened footing should meet the setback as described above. 5.2.4 Preliminary Floor Slab Design The slab-on-grade should be at least 5 inches thick and be reinforced with No. 3 rebars 18 inches on center or No. 4 rebars at 24 inches on center, each way. All reinforcing should be placed at mid-height in the slab. Slabs should be underlain by a 2-inch layer of clean sand (SE>30), underlai n by a 1 0-mil visqueen moisture barrier and an additional 2 inches of sand. We recommend control joints be provided across the slab at appropriate intervals as designed by the project architect. -15-Leighton 041265-001 The potential for slab cracking may be reduced by careful control of water/cement ratios. The contractor should take appropriate curing precautions during the pouring of concrete in hot weather to minimize cracking of slabs. We recommend that a slipsheet (or equivalent) be utilized if grouted tile, marble tile, or other crack-sensitive floor covering is planned directly on concrete slabs. All slabs should be designed in accordance with structural considerations. If heavy vehicle or equipment loading is proposed for the slabs, greater thickness and increased reinforcing may be required as determined by the structural engineer. 5.2.5 Settlement The recommended allowable-bearing capacity is based on a maximum total and differential settlements estimated at less than 3/4 of an inch, and 1/2 of an inch in 20 feet, respectively. Since settlements are a function of footing size and contact bearing pressures, some differential settlement can be expected between adjacent columns or walls where a large differential loading condition exists. However for most cases, differential settlements between adjacent footings are considered unlikely to exceed 1/2 of an inch. 5.3 Lateral Earth Pressures For design purposes, the following lateral earth pressure values for level or sloping backfill are recommended for walls backfilled with on-site soils or approved granular material of very low to low expansion potential. Table 3 Static Equivalent Fluid Weight (pcf) Conditions Level 2:1 Slope Active 35 55 At-Rest 55 65 Passive 350 150 (Maximum of 3 ksf) (sloping down) Umestrained (yielding) cantilever walls up to 10 feet in height should be designed for an active equivalent pressure value provided above. In the design of walls restrained from movement at the top (nonyielding) such as basement walls, the at-rest pressures should be used. If conditions other than those covered herein are anticipated, the equivalent fluid pressure values should be provided on an individual case basis by the geotechnical -16-Leighton 041265-001 engineer. A surcharge load for a restrained or umestrained wall resulting from automobile traffic may be assumed to be equivalent to a uniform pressure of 75 psf which is in addition to the equivalent fluid pressure given above. For other uniform surcharge loads, a uniform pressure equal to 0.35q should be applied to the wall (where q is the surcharge pressure in psf). The wall pressures assume walls are backfilled with free draining materials and water is not allowed to accommodate behind walls. A typical drainage design is presented in Appendix D. Wall backfill should be compacted by mechanical methods to at least 90 percent relative compaction (based on ASTM D1557). Wall footings should be designed in accordance with the foundation design recommendations and reinforced in accordance with structural considerations. For all retaining walls, we recommend a minimum horizontal distance from the outside base of the footing to daylight of 1 0 feet. Lateral soil resistance developed against lateral structural movement can be obtained from the passive pressure value provided above. Further, for sliding resistance, the friction coefficient of 0.35 may be used at the concrete and soil interface. These values may be increased by one-third when considering loads of short duration including wind or seismic loads. The total resistance may be taken as the sum of the frictional and passive resistance provided that the passive portion does not exceed two-thirds of the total resistance. The geotechnical consultant should approve any backfill materials that will be utilized prior to the backfill placement operations. lt is th e contractors responsibility to provide representative samples of the selected backfill material. 5.4 Geochemical Considerations Geochemical screening of the as-graded surface soils should be performed to confirm our preliminary test results and assumptions. 5.5 Slope Stability Our review of the project grading plan indicates that cut and fill slopes at inclinations of 2:1 (horizontal to vertical) or flatter are proposed. Cut slopes on the order of approximately 5 to 8 feet in height are proposed within the central portion of the site to reach the finished grades of Lots 7 through 10. A fill slope with an approximate maximum height of 15 feet is proposed along the eastern margin of the site, descending from the proposed Lots 12 and 13. Slope heights are approximate and based on the referenced project grading plan (CIVCOM, 2004). -17-Leighton 041265-001 The proposed cut and fill slopes, at the proposed heights and gradients, are expected to possess a calculated factor of safety of greater than 1.5 within respect to potential deep- seated failure. Cut slopes should be geologically mapped during grading to evaluate the exposed conditions. Slopes should be provided with appropriate surface drainage features and landscaped with drought-tolerant, slope-stabilizing vegetation as soon as possible after grading to reduce the potential for erosion. Berms should be provided at the top of fill slopes, and brown ditches should be constructed at the top of cut slopes. Lot drainage should be directed such that runoff on slope faces is minimized. Inadvertent oversteepning slopes should be avoided during fine grading and building construction. If seepage is encountered in slopes, special drainage features may be recommended by the geotechnical consultant. 5.6 Preliminary Pavement Design The appropriate Asphalt Concrete (AC) and Class 2 aggregate base (AB) pavement section will depend on the type of subgrade soil, shear strength, traffic load, and planned pavement life. Since an evaluation of the actual subgrade soils cannot be made at this time, we have assumed an R-value of 12 and Traffic Indexes (TI) of 6.0. The pavement sections presented on Table 4 are to be used for preliminary planning purposes only. Final pavement designs should be completed in accordance with the City of Carlsbad design criteria after R-value tests have been performed on the actual subgrade materials. Table 4 Preliminary Pavement Section Designs Traffic Assumed Preliminary Pavement Section Index R-Value 6.0 12 4 inches AC over 12 inches Class 2 Aggregate Base Asphalt Concrete (AC) and Class 2 aggregate base should conform to and be placed in accordance with the latest revision of California Department of Transportation Standard Specifications. Prior to placing the pavement section, the subgrade soils should have a relative compaction of at least 95 percent to a minimum depth of 12 inches (based on ASTM Test Method D1557). Aggregate Base should be compacted to a minimum of 95 percent relative compaction (based on ASTM Test Method D 1557) prior to placement of the AC. -18-Leighton 041265-001 If pavement areas are adjacent to heavily watered landscaping areas, we recommend some measures of moisture control be taken to prevent the subgrade soils from becoming saturated. It is recommended that the concrete curbing, separating the landscaping area from the pavement, extend below the aggregate base to help seal the ends of the sections where heavy landscape watering may have access to the aggregate base. Concrete swales should be designed if asphalt pavement is used for drainage of surface waters. 5.7 Control of Surface Water and Drainage Surface drainage should be carefully taken into consideration during precise grading, landscaping, and building construction. Positive drainage (e.g., roof gutters, downspouts, area drain, etc.) should be provided to direct surface water away from structures and towards the street or suitable drainage devices. Ponding of water adjacent to structures should be avoided; roof gutters, downspouts, and area drains should be aligned so as to transport surface water to a minimum distance of 5 feet away from structures. The performance of structural foundations is dependent upon maintaining adequate surface drainage away from structures. Water should be transported off the site in approved drainage devices or unobstructed swales. We recommend that the minimum flow gradient for the drainage be 1-percent for area drains and paved drainage swales; and 2-percent for unpaved drainage swales. We recommend that where structures will be located within 5 feet of a proposed drainage swale, the surface drainage adjacent to the structures be accomplished with a gradient of at least 3-1 /2 percent away from the structure for a minimum horizontal distance of 3 feet. Drainage should be further maintained by a swale or drainage path at a gradient of at least 1-percent for area drains and paved drainage swales and 2-percent for unpaved drainage swales to a suitable collection device (i.e. area drain, street gutter, etc.). We also recommend that structural footings within 4 feet of the drainage swale flowline be deepened so that the bottom of the footing is at least 12 inches below the flow-line of the drainage swale. In places where the prospect of maintaining the minimum recommended gradient for the drainage swales and the construction of additional area drains is not feasible, provisions for specific recommendations may be necessary, outlining the importance of maintaining positive drainage. The impact of heavy irrigation or inadequate nmoff gradient can create perched water conditions, resulting in seepage or shallow groundwater conditions where previously none existed. Maintaining adequate surface drainage and controlled irrigation will significantly reduce the potential for nuisance-type moisture problems. To reduce differential earth movements (such as heaving and shrinkage due to the change in moisture content of foundation soils, which may cause distress to a structure or improvement), the moisture content of the soils surrounding the structure should be kept as relatively constant as possible. -19- Leighton 041265-001 All area drain inlets should be maintained and kept clear of debris in order to function properly. Rerouting of site drainage patterns and/or installation of area drains should be performed, if necessary. A qualified civil engineer or a landscape architect should be consulted prior to rerouting of drainage. 5.8 Slope Maintenance Guidelines It is the responsibility of the owner to maintain the slopes, including adequate planting, proper inigation and maintenance, and repair of faulty inigation systems. To reduce the potential for erosion and slumping of graded slopes, all slopes should be planted with ground cover, shrubs, and plants that develop dense, deep root structures and require minimal inigation. Slope planting should be carried out as soon as practical upon completion of grading. Surface-water runoff and standing water at the top-of-slopes should be avoided. Oversteepening of slopes should be avoided during construction activities and landscaping. Maintenance of proper lot drainage, undertaking of property improvements in accordance with sound engineering practices, and proper maintenance of vegetation, including regular slope inigation, should be performed. Slope irrigation sprinklers should be adjusted to provide maximum uniform coverage with minimal of water usage and overlap. Overwatering and consequent runoff and ground saturation should be avoided. If automatic sprinklers systems are installed, their use must be adjusted to account for rainfall conditions. Trenches excavated on a slope face for any purpose should be properly backfilled and compacted in order to obtain a minimum of 90 percent relative compaction, in accordance with ASTM Test Method D 1557. Observation/testing and acceptance by the geotechnical consultant during trench backfill is recommended. A rodent-control program should be established and maintained. Prior to planting, recently graded slopes should be temporarily protected against erosion resulting from rainfall, by the implementing slope protection measures such as polymer covering, jute mesh, etc. 5.9 Landscaping and Post-Construction Landscaping and post-construction practices canied out by the owner(s) and their representative bodies exert significant influences on the integrity of structures founded on expansive soils. Improper landscaping and post-construction practices, which are beyond the control of the geotechnical engineer, are frequently the primary cause of distress to these structures. Recommend ations for proper landscaping and post-construction practices are provided in the following paragraphs within this section. Adhering to these recommendations will help in minimizing distress due to expansive soils, and in ensuring that such effects are limited to cosmetic damages, without compromising the overall integrity of structures. -20-Leighton 041265-001 Initial landscaping should be done on all sides adjacent to the foundation of a structure, and adequate measures should be taken to ensure drainage of water away from the foundation. If larger, shade providing trees are desired, such trees should be planted away from structures (at a minimum distance equal to half the mature height of the tree) in order to prevent penetration of the tree roots beneath the foundation of the structure. Locating planters adjacent to buildings or structures should be avoided as much as possible. If planters are utilized in these locations, they should be properly designed so as to prevent fluctuations in the moisture content of subgrade soils. Planting areas at grade should be provided with appropriate positive drainage. Wherever possible, exposed soil areas should be above paved grades. Planters should not be depressed below adjacent paved grades unless provisions for drainage, such as catch basins and drains, are made. Adequate drainage gradients, devices, and curbing should be provided to prevent runoff from adjacent pavement or walks into planting areas. Watering should be done in a uniform, systematic manner as equally as possible on all sides of the foundation, to keep the soil moist. Irrigation methods should promote uniformity of moisture in planters and beneath adjacent concrete flatwork. Overwatering and underwatering of landscape areas must be avoided. Areas of soil that do no have ground cover may require more moisture, as they are more susceptible to evaporation. Ponding or trapping of water in localized areas adjacent to the foundations can cause differential moisture levels in subsurface soils and should, therefore, not be allowed. Trees located within a distance of20 feet of foundations would require more water in reriods of extreme drought, and in some cases, a root injection system may be required to maintain moisture equilibrium. During extreme hot and dry periods, close observations should be carried out around foundations to ensure that adequate watering is being undertaken to prevent soil from separating or pulling back from the foundations. 5.10 Construction Observation and Testing Construction observation and testing should be performed by the geotechnical consultant dw-ing the remaining grading operations, future excavations and fow1dation or retaining wall construction on the graded portions of the site. Additionally, footing excavations should be observed and moisture determination tests of subgrade soils should be performed by the geotechnical consultant prior to the pouring of concrete. Foundation design plans should also be reviewed by the geotechnical consultant prior to excavations. -21-Leighton 041265-001 6.0 LIMITATIONS The conclusions and recommendations in this report are based in part upon data that were obtained from a limited number of observations, site visits, excavations, samples, and tests. Such information is by necessity incomplete. The nature of many sites is such that differing geotechnical or geological conditions can occur within small distances and under varying climatic conditions. Changes in subsurface conditions can and do occur over time. Therefore, the findings, conclusions, and recommendations presented in this report can be relied upon only if Leighton and Associates has the opportunity to observe the subsurface conditions during grading and construction of the project, in order to confirm that our preliminary findings are representative for the site. -22-Leighton ----------------- 40 20 0 40 80 120 GRAPHIC SCALE 1'= 40' EXIS T ST EXIST. AC I FGEND (FOR GEOTECHNICAL MAP) A fu ARTIFICIAL FILL -UNDOCUMENTED (QUERIED WHERE UNCERTAIN) Qsw Qt SLOPEWASH/COLLUVIAL DEPOSITS UNDERLAIN BY QUATERNARY TERRACE MATERIAL (CIRCLED WHERE BURIED, QUERIED WHERE UNCERTAIN) Qt QUATERNARY TERRACE DEPOSITS (CIRCLED WHERE BURIED, QUERIED WHERE UNCERTAIN) --••• ? GEOLOGIC CONTACT (DASHED WHERE APPROXIMATE, DOTTED WHERE BURIED, QUERIED WHERE UNCERTAIN) APPROXIMATE LOCATION OF EXPLORATORY TRENCH WITH TOTAL DEPTH INDICATED PLATE 1 GEOTECHNICAL MAP Nobel Homes at Black Rail Road Carlsbad, California PROJECT: 041265-001 SCALE: 1"=40' DATE: Sept. 2004 ENGINEER/GEOLOGIST: BJD/WDO DRAFTED BY: KAM Leighton and Associates, Inc. A LEIGHTON GROUP COMPANY T i I I . 'I BASE MAP: CIVCOM & Associo\es, 2004 0 .c."-'-~-----~~----~---------- Tl i~TA T I VE f~AP NO CCDP 04 -) I i HD P 04- CIT Y OF ) LCP A 04- CARLSBAD/) [] N S CE L COURT CT 04 - ) ZC 04 -) 0 tn (') J fc--"'-"-----1 I 358. 3 I © -1 ~ zu__ D ~z (/)<[ (/)_j W!l. "' !l.W Q_Q_ ::0 <[ V>U Afu [NGJN[[R Or WORK R. BHATIA CIVCOM & ASSOCIATES 3665 RUFFIN ROAD SUIT£ 230 SAN DIE:GO, CA 92123 (858)505-8800 3 =14' R. BHATIA R. C. E 51348 EXP. 6-30-06 , ... .' __ ! NOTE LEGEND (CIVCOM, 2004) SU BDIV ISION BOUND ARY ---------------- LO T LINE ---------------------------- LOT NUMBER --------------~----------- PAD EL EVAT ION----------------------- FLOOR PLAN NUMBER------------------- WATER LINE & VALVE------------------ FIRE HYDRANT------------------------ SEWER MANHOLE, MANHOLE NO. , --------- SEWER CLEANOUT---------------------- EXIST. CURB IN LET------------------- EXIST. STORM DRAIN AND CLEANOUT ---- EXISTING CONTOUR---c---------------- PRD POSED CONTOUR-------------: _____ _ STREET ELEVATIO N----------c---------- STREET GRADE -----~----------------- RETAINING WALL----------------------- DIRE CTION OF FLOW------------------ ---- CD )347. sj PLAN! a ~ --o- ..• -----·· 36 0---...... __ _ . ·-.. -350-.. 2. 00% STRUCTURES ON LOTS 12 & 13 SHALL BE CONSTRUCTED IN CONF ORMANCE WITH SECTION 504 OF THE 1997 EDITION OF THE URBAN WILDLIFE INTER FACE CODE. I. ·. APPROVED PLANNING DEPARTMENT ; CITY OF CA RLSBAD ENG INEERING DEPAR TMEN T CITY OF CARLSBAD DATE DATE T£NTA TI V£ MAP SH££T 2 OF" 2 041265-001 APPENDIX A References California Building Standards Commission (CBSC), 1998, California Building Code, Volume I - Administrative, Fire-and Life-Safety, and Field Inspection Provisions, Volume II - Structural Engineering Design Provisions, and Volume III -Material, Testing and Installation Provision, ICBO. CDMG, 1996, Probabilistic Seismic Hazard Assessment for the State of California, Open-File Report, 96-08. CIVCOM & Associates, Inc., 2004, "Tentative Map Tract No. CT-04-(CDB 04-, HDP 04- LCP A 04-2C 04-) City of Carlsbad" Tentative Map Sheet 2 of 2, Undated digital file provided September 10, 2004. Hart, E.W., 1997, Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zones Maps: Department of Conservation, Division of Mines and Geology, Special Publication 42. International Conference of Building Officials (ICBO), 1997, Uniform Building Code, Volume I- Administrative, Fire-and Life-Safety, and Field Inspection Provisions, Volume II - Structural Engineering Design Provisions, and Volume III -Material, Testing and Installation Provision, ICBO. Jennings, C. W., 1994, Fault Activity Map of California and Adjacent Areas; California Division of Mines and Geology, Geologic Data Map 6, Scale 1:750,000. Leighton and Associates, Inc., 1992, City of Carlsbad Geotechnical Hazards Analysis and Mapping Study, 84 Sheets, dated November 1992. Tan, S.S. and Kennedy, M.P., 1996, Geologic Maps ofthe Northwestern Part of San Diego Cow1ty, California, DMG Open-file Report 96-02, Plates 1 and 2, Scale 1:24,000. A-1 E LOG OF TRENCH: _ __L.:;._,__ __ _ Project Name: Noble Homesffilack Rail Road__ Logged by: ___ _G__u.[~JMu..u _____________ 1 ENGINEERING PROPERTIES Project Number: _....~.OL::J4ul...c..2li6..l.S-::..~.OLLOu.l ________ _ Elevation: ___ _:lt_; "1'it.::t:.._·4' -------------1 Equipment: Backhoe Location/Grid: See M ap GEOLOGIC GEOLOGIC ATTITUDES DATE: 8/3/04 DESCRIPTION: UNIT uses Sample No. Moisture (%) Density (pcf) ARTIFICIAL FILL A @ 0': Silty fine to medium SAND: Red-brown to orange br own, dry to damp, loose to medium dense B @ .5 ': Silty fine to medium gravelly SAND: Light gray to gray-brown, damp, loose to medium dense: angular gravels to 3/4", concrete chunks to 6" C @ l ': Silty fine to medium SAND: Red-brown, damp to moi st, loose to medium dense; friable QUA TERNARY TERRACE DEPOSITS D @ 3': Silty fine to medium SAND: Red-brown, damp to moist, medium dense; weathered, roots @ 4': Becomes dense @ 5': Becomes very dense Af Qt GRAPHICAL REPRESENTATION: East Wall SCALE: 1 "=5' SURFACE SLOPE: oo B ..... ..... ... .. . . .. . .... ·-·· ... · ................. ' ,._ ... / SM TREND:N/S Total Depth= 7 Feet No Ground Water Encountered Backfilled: August 3, 2004 LOG OF TRENCH: _ __..~....:;;-..._7 ___ _ ~-----------------------------------------,--------------, Project Name: Noble Homes/Black Rail Road_ Logged by: ___ _u. Gr.JMI..J.ll _____________ l ENGINEERING PROPERTlES Project Number: --'-0=4'-'-1 ..... 2.u.6...J..:5-::..~..0u.JO'-l.l ________ _ Elevation: ____ lL: ')u:.__7' ----------------1 Equipment: Backhoe Location/Grid: See Map GEOLOGIC GEOLOGIC ATTITUDES DATE: 8/3/04 DESCRIPTION: UNIT uses Sample No. Moisture (%) Density (pcf) TOPSOIL A @ 0': Silty fine SAND: Light brown, dry, loose QUATERNARY TERRACE DEPOSITS B @ 1 ': Silty fine to medium SAND: Orange-brown to red-brown, damp to moist, loose to medium dense @ 3': Becomes friable @ 7': Becomes dense to very dense Qt GRA PHICAL REPRESENTATION: East Wall SCALE: 1 "=5' SURF ACE SLOPE: 0° .··;·:···.:·,. :· .... ·;.-/,: ·····':··'!"··.···: ······.· .. .. ... .. " •• • • •• I ..... .....-•• .' .: .... •' , 4• ~ ....... : ...... ·_/ ·::·:: ...... · .. ·.··.··.:.· .. ·.··.··· : ....... ·./·. • • ~. ~ ...... ., ... lo .. " • •' •to \. .......... /... ~ .......... •• SM TREND: N/S Total Depth = 8 Feet No Ground Water Encountered Backfilled: August 3, 2004 Project Name: __ __.N_,_,o .... b.u.l..,_e_._H...,olJ.Jm....,e""'s"-'!B ..... l..,.a""ck..._R....,.....ai .... l"""R ..... o"'"ad..___ Logged by: __ _,G..._.r .. TMLJ...LL. ___________ 1 Project Number: _..u0=4.._.12'"""6 ..... 5=-0w.O..__.l _______ _ Elevation: ___ _. 3::%..4~-'-"'-------------1 Eq uipment: Backhoe Location/Grid: See Map GEOLOGIC UNIT GEOLOGIC DATE: 8/3/04 ATTITUDES DESCRIPTION: ARTIFICIAL FILL A @ 0': Silty fine to medium SAND: Mottled, orange brown and light gray, dry to damp, loose B @ 7': Abundant roots and vegetation QUATERNARY SLOPEWASH C @ 8': Silty fine SAND: Orange-brown, dry, loose; friable QUATERNARY TERRACE DEPOSITS D @ 13': Silty fine to medium SAND: Orange-brown, damp, medium dense to dense Af Qsw Qt GRAPHICAL REPRESENTATION: North Wall SCALE: 1 "=5' SURF ACE SLOPE: 0° \ ... . ........... --· ....... ·. ~ ........ , ........... r·· ... <# .,. : " • • " ... " It~ .... \, \, ! • . "! ,. I' .. .. .. .. .. " t ••• ·~ • ~ _, .. ~. \ f ¥ "' I \ot. •" • • •, o ~~' "' •'"' • , • • • ' ""• • • "" •'• l\)1.,,.,., I I • ,• • ,-~ • •' •4 ,11,.•., ·,·, ~· .,1 •,,., J' ~ ·~.··.·· ... ·•· •.. ... '·.· .. ••• ,.,. .": .t>', ··.,. ..• ·""· .·, ...... • .. -~.·· .~·-: . A . .. . ... • • .. .. • ..·. • I> • 4 \,0 ••• .. ... .. 4 • • ~ ( .. •• ~ : • • ... ... • • LOG OF TRENCH: _ _..Jic..:;-..L3 ___ _ ENGINEERING PROPERTIES uses SM Sample Moisture Density No. (%) (pet) B-1@ 0-5' TREND: E/W Total Depth= 14 Feet No Ground Water Encountered Backfilled: August 3, 2004 LOG OF TRENCH: _ _,Tc..=.-4:t__ __ _ ~-----------------------------------------------------------------------------,---------------------------. Project Name: Noble Homes/Black Rail Roa.d.__ Logged by: --~c.LJ;JM!l.YJ... ______________ I ENGINEERING PROPERTIES Project Number: _..1J0!.:±4..Ll2LJ6u.5.L:-:uOlLOLJ ________ _ Elevation: ___ _) l: . ...J.<;;lLn' ___________ ~-1 ~E~q~ut~p~m~e~n~t~: ~=====B~a=c~kh~a~e=·=================~~L~o~c~m~io~r~v~G~n~·d~:====S~PP~~~~,.,~n==========~=========== GEOLOGIC DATE: 8/3/04 DESCRIPTION: ATTITUDES ~----~--------~--------------------------+-----~~~+-~~~-~-L--+-~~~ ARTIFICIAL FILL (Af) A @ 0': Silty fine to medium SAND: Orange-brown, dry to damp, loose to medium dense, gravels @ 7': Abundant vegetation and roots QUATERNARY SLOPEWASH B @ 8': Silty fine SAND: Light orange-brown, dry, loose; friable QUATERNARY TERRACE DEPOSITS C @ 10': Silty fine to medium SAND: Orange-brown, damp, medium dense; Qsw Qt GRAPHICAL REPRESENTATION: East Wall SCALE: 1"=5' SURF ACE SLOPE: 0° TREND: N/S -------.------,------~-----~-----,-------,-----~-----,------,------4 I .. • . .. .. • ..• .•.. .. • ... ... . . , .. -r Total Depth= 10 Feet No Ground Water Encountered Backfilled: August 3, 2004 Project N arne: __ ....~N~oi.LJb..~.~J~e..LH.uoLLmwe.,.;s"-'/B'"'"J .... al<Jckllo.....L>R..._a!u... I ...~.:R .... ow.a>Ld _ Logged by: __ __.:G~. TT.u.uM ____________ 1 Project Number: _ _LOl!:t4..Ll.<..c26lL5.L:-:.uOuO-'-l _______ _ Elevation: ___ _Jl--L 5il.L0' _____________ 1 Equ ipment: GEOLOGIC ATTITUDES Backhoe Location/Grid: See Map DATE: 8/3/04 DESCRIPTION: ARTIFICIAL FILL A @ 0': Silty fine to medium SAND: Orange-brown, dry to damp, loose to medium dense @ 3': Silty fine to medium SAND: Light gray, damp to moi st, loose to medium dense TOPSOIL B @ 5': Silty fine SAND: Brown to red-brown, dry to damp, loose to medium dense; roots, vegetation, friable QUATERNARY SLOPEWASH GEOLOGIC UNIT Af C @ 7': Silty fine SAND: Orange-brown, dry to damp, loose to medium dense; Qsw friable QUATERNARY TERRACE DEPOSITS Qt D @ 9': Silty fine to medium SAND: Orange-brown, damp to moist, medium dense to dense GRAPHICAL REPRESENTATION: NEWall SCALE: 1"=5' SURF ACE SLOPE: 0° ""'··· __ • .. ·\.~'".;•\1· .. "· ... ., ... "" • .,· ... ., .. .,· ... "".,"""·-· ••• • •• ·:/ \·. ·• • • . -f-..<":· • .·" ·• . •. .--< , ·. '·· . I \.':· ''t" -~. ~ ••• -.... 'j '7 ~ ., .,. • • f """• ·.~ : I t .,-J--' .. o "\..._~: :._ ·.-... _' .. :c·: •... ( ... ·. =:: ·.,:;· ~ ....... ; • • • ..... "J ~~-~:_: .. :·· tS .. ·.· ~~~ : ~-.. ~ ..... : .. :--~ .. J LOG OF TRENCH: _ _,T'-"-..L-5 ___ _ ENGINEERING PROPERTIES uses SM Sample Moisture Density No. (%) (pcf) B-1 @ 0-5' TREND: N40°W Total Depth= 11 Feet No Ground Water Encountered Backfilled: August 3, 2004 LOG OF TRENCH: _ _.T._-.._6 ___ _ Project Name: Noble Homes/Black Rail Ro Logged by: GTM ENGINEERING PROPERTIES Project Number: 04 J?6S-OOJ --Elevati on: 147' Eq uipment: Bacl>b oe Locati on/Grid: <::_pp Mc:~n -GEOLOGIC Sample Moisture Density DESCRIPTION: UNIT uses No. (%) (pcf) GEOLOGIC DATE: 8/3/04 .1\ TTITUDES QUATERNARY TERRACE DE 10SITS Qt A @0': Silty fine to medit 1m SAND: Orange-brown to red-brown, moist, SM medium dense; weathere• :l @ 1': Silty fine to mediu m SAND: Mottled orange-brown and gray, moist to wet, dense; not' v eathered GRAPHICAL REPRESENTATION: SCALE: 1"=5' SURF ACE SLOPE: 0° TREND: N/S -.·. -~·-... ,_ / .. • • • • 'lo • } :· ... ' .. ' ~ : ~:.' " \:· :-·. ·.::·.<·;: .. \:·v .. A))Y :·;:_:. ;· •. : _: .. :~ ·~. Total Depth = 3 Feet No Ground Water Encountered Backfilled: August 3, 2004 LOGOFTRENCH: --~~------- Project Name: Noble Homes/Black Rail Road __ Logged by: GJM ENGINEERJNG PROPERTIES Project Number: 041265-001 ----Elevation: 155' Equipment: Backhoe Location/Grid: See Map GEOLOGIC GEOLOGIC Sample Moisture Density ATTITUDES DATE: 8/3/04 DESCRIPTION: UNIT uses No. (%) (pet) QUATERNARY TERRACE DEPOSITS Qt A @ 0': Silty fine to medium SAND: Orange-brown, damp to moist, medium SM dense @ 4': Becomes dense, c1::mented GRAPHICAL REPRESENTATION: SEWall SCALE: 1 "=5' SURF ACE SLOPE: 0° TREND: N45°E ---. . .. "'.. I ..... ·."·:~-:··~·:·--:.· v , . .. . . .. . .,. · .... -... \1'··:. ~ t. .. .. •• . . . .. . .... .. .... · .. · ... · .. ~ ..... . . . .. .. .· :. ... ": .-: .... -':) .... ._ .. :-.,:: ~ :: .... ~ .. : .. ; : .. : .. · ', :·t . ,;' .. 41. ~-··· -~Z/ .. :·; • *' ......... , .. Total Depth = 5.5 Feet I No Ground Water Encountered Backfilled: August 3, 2004 I LOGOFTRENCH: --~I~-8~------ Project Name: Noble Homes/Black Rail Ro.;ld..______ Logged by:---~ Cl..rj.JMl.l.ll _____________ 1 ENGINEERING PROPERTIES Project Number: _.1JO:::t4_.~_l2kl6J_SJ..::-.u01LOLJ _________ _ Elevation: ____ lL: 'iw;.srL'-------------1 Equipment: Backhoe Location/Grid: GEOLOGIC GEOLOGIC ATTITUDES DATE: 8/3/04 DESCRIPTION: UNIT uses Sample No. Moisture (%) Density (pcf) QUATERNARY TERRACE DEPOSITS A @ 0': Silty fine to medium SAND: Orange-brown, red-brown, damp to moist, medium dense to dense @ 2': Becomes dense Qt GRAPHICAL REPRESENTATION: North Wall SCALE: 1 "=5' SURF ACE SLOPE: oo SM TREND: E/W Total Depth = 4.5 Feet No Ground Water Encountered Backfilled: August 3, 2004 ( 041265-001 APPENDIX C Laboratory Testing Procedures and Test Results Expansion Index Tests: The expansion potential of selected materials was evaluated by the Expansion Index Test, UBC Standard No. 18-2 and/or ASTM Test Method 4829. Specimens are molded under a given compactive energy to approximately the optimum moisture content and approximately 50 percent saturation or approximately 90 percent relative compaction. The prepared l-inch thick by 4-inch diameter specimens are loaded to an equivalent 144 psf surcharge and are inundated with tap water until volumetric equilibrium is reached. Sample Description Expansion Index Expansion Potential Reddish-brown silty 1 Very Low sand Soluble Sulfates: The soluble sulfate contents of selected samples were determined by standard geochemical methods (Caltrans Test Method CT417). Sample Location Soluble Content % Potential Degree of Sulfate Attack T-4 0.024 Negligible Maximum Dry Density Tests: The maximwn dry density and optimum moisture content of typical materials were determined in accordance with ASTM Test Method D1557. The results of these tests are presented in the table below: Sample Description Maximum Dry Optimum Moisture Content Density (pcf) (%) Reddish-brown silty 126.5 10.0 sand Reddish-brown silty 130.0 9.5 sand C-1 Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page 1 of 6 LEIGHTON AND ASSOCIATES, INC. GENERAL EARTHWORK AND GRADING SPECIFICATIONS FOR ROUGH GRADING 1.0 General 3030.1094 1.1 Intent: These General Earthwork and Grading Specifications are for the grading and earthwork shown on the approved grading plan(s) and/or indicated in the geotechnical report(s). These Specifications are a part of the recommendations contained in the geotechnical report(s). In case of conflict, the specific recommendations in the geotechnical report shall supersede these more general Specifications. Observations of the earthwork by the project Geotechnical Consultant during the course of grading may result in new or revised recommendations that could supersede these specifications or the recommendations in the geotechnical report(s ). 1.2 The Geotechnical Consultant of Record: Prior to commencement of work, the owner shall employ the Geotechnical Consultant of Record (Geotechnical Consultant). The Geotechnical Consultants shall be responsible for reviewing the approved geotechnical report(s) and accepting the adequacy of the preliminary geotechnical findings, conclusions, and recommendations prior to the commencement of the grading. Prior lo commencement of grading, the Geotechnical Consultant shail rev iew the "work plan" prepared by the Earthwork Contractor (Contractor) and schedule sufficient persom1el to perform the appropriate level of observation, mapping, and compaction testing. During the grading and earthwork operations, the Geotechnical Consultant shall observe, map, and document the subsurface exposures to verify the geotechnical design assumptions. If the observed conditions are found to be significantly different than the interpreted assumptions during the design phase, the Geotechnical Consultant shall inform the owner, recommend appropriate changes in design to accommodate the observed conditions, and notify the review agency where required. Subsurface areas to be geotechnically observed, mapped, elevations recorded, and/or tested include natural ground after it has been cleared for receiving fill but before fill is placed, bottoms of all "remedial removal" areas, all key bottoms, and benches made on sloping ground to receive fill. The Geotechnical Consultant shall observe the moisture-conditioningand processing of the subgrade and fill materials and perform relative compaction testing of fill to determine the attained level of compaction. The Geotechnical Consultant shall provide the test results to the owner and the Contractor on a routine and frequent basis. Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page 2 of 6 1.3 The Earthwork Contractor: The Earthwork Contractor (Contractor) shall be qualified, experienced, and knowledgeable in earthwork logistics, preparation and processing of ground to receive fill, moisture-conditioning and processing of fill, and compacting fill. The Contractor shall review and accept the plans, geotechnical report(s), and these Specifications prior to commencement of grading. The Contractor shall be solely responsible for perfonning the grading in accordance with the plans and specifications. The Contractor shall prepare and submit to the owner and the Geotechnical Consultant a work plan that indicates the sequence of earthwork grading, the number of "spreads" of work and the estimated quantities of daily earthwork contemplated for the site prior to commencement of grading. The Contractor shall inform the owner and the Geotechnical Consultant of changes in work schedules and updates to the work plan at least 24 hours in advance of such changes so that appropriate observations and tests can be planned and accomplished. The Contractor shall not assume that the Geotechnical Consultant is aware of all grading operations. The Contractor shall have the sole responsibility to provide adequate equipment and methods to accomplish the earthwork in accordance with the applicable grading codes and agency ordinances, these Specifications, and the recommendations in the approved geotechnical report(s) and grading plan(s). If, in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as unsuitable soil, improper moisture condition, inadequate compaction, insufficient buttress key size, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the Geotechnical Consultant shall reje<.:i Lhe work and 111ay re~.:ommend to the owner that wnstru~.:tiu11 be sluppeJ u11tii the conditions are rectified. 2.0 Preparation of Areas to be Filled 3030.1094 2.1 Clearing and Grubbing: Vegetation, such as brush, grass, roots, and other deleterious material shall be sufficiently removed and properly disposed of in a method acceptable to the owner, governing agencies, and the Geotechnical Consultant. TI1e Geotechnical Consultant shall evaluate the extent of these removals depending Oil specific site conditions. Earth fill material shall not contain more than 1 percent of organic materials (by volume). No fill lift shall contain more than 5 percent of organic matter. Nesting of the organic materials shall not be allowed. If potentially hazardous materials are encountered, the Contractor shall stop work in the affected area, and a hazardous material specialist shall be informed immediately for proper evaluation and hand! ing of these materials prior to continuing to work in that area. As presently defined by the State of California, most refined petroleum products (gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered to be hazardous waste. As such, the indiscriminate dumping or spillage of these fluids onto the ground may constitute a misdemeanor, punishable by fines and/or imprisonment, and shall not be a ll owed. Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page3 of 6 2.2 Processing: Existing ground that has been declared satisfactory for support of fill by the Geotechnical Consultant shall be scarified to a minimum depth of 6 inches. Existing ground that is not satisfactory shall be overexcavated as specified in the following section. Scarification shall continue until soils are broken down and free of large clay lumps or clods and the working surface is reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction. 2.3 Overexcavation: In addition to removals and overexcavations recommended in the approved geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy, organic-rich, highly fractured or otherwise unsuitable ground shall be overexcavated to competent ground as evaluated by the Geotechnical Consultant during grading. 2.4 Benching: Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units), the ground shall be stepped or benched. Please see the Standard Details for a graphic illustration. The lowest bench or key shall be a minimum of 15 feet wide and at least 2 feet deep, into competent material as evaluated by the Geotechnical Consultant. Other benches shall be excavated a minimum height of 4 feet into competent material or as otherwise recommended by the Geotechnical Consultant. Fill placed on ground sloping flatter than 5:1 shall also be benched or otherwise overexcavated to provide a flat subgrade for the fill. 2.5 Evaluation/Acceptance of Fill Areas: All areas to receive fill, including removal and procc;ssed areas, key boltulllS, ami Uclicilt:S, ~JI<ti j ue ub~t:l veJ, 111apped, elevations recorded, and/or tested prior to being accepted by the Geotechnical Consultant as suitable to receive fill. The Contractor shall obtain a written acceptance from the Geotechnical Consultant prior to fill placement. A li censed surveyor shal l provide the survey control for de term in ing elevations of processed areas, keys, and benches. 3.0 Fill Material 3030.1094 3.1 General: Material to be used as fill shall be essentially free of organic matter and other deleterious substances evaluated and accepted by the Geotechnical Consultant prior to placement. Soils of poor quality, such as those with unacceptable gradation, high expansion potential, or low strength shall be placed in areas acceptable to the Geotechnical Consultant or mixed with other soi ls to achieve satisfactory fill material. 3.2 Oversize: Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 8 inches, shall not be buried or placed in fill unless location, materials, and placement methods are specifically accepted by the Geotechnical Consultant. Placement operations shal l be such that nesting of oversized material does not occur and such that oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 ve1tical feet of finish grade or within 2 feet of future utilities or underground construction. Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECTFICA TTONS Page4 of 6 3.3 Import: If importing of fill material is required for grading, proposed import material shall meet the requirements of Section 3.1. The potential import source shall be given to the Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that its suitability can be determined and appropriate tests performed. 4.0 Fill Placement and Compaction 3030.1094 4.1 Fill Layers: Approved fill material shall be placed in areas prepared to receive fill (per Section 3 .0) in near-horizontal layers not exceeding 8 inches in loose thickness. The Geotechnical Consultant may accept thicker layers if testing indicates the grading procedures can adequately compact the thicker layers. Each layer shall be spread evenly and mixed thoroughly to attain relative uniformity of material and moisture throughout. 4.2 Fill Moisture Conditioning: Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to attain a relatively uniform moisture content at or slightly over optimum. Maximum density and optimum soil moisture content tests shall be performed in accordance with the American Society of Testing and Materials (ASTM Test Method Dl557-9 1). 4.3 Compaction of Fill: After each layer has been moisture-conditioned, mixed, and evenly spread. it shall be uniformly compacted to not less than 90 percent of maximum dry density (AST!vl Tt:sl Mdhud D 1557-9 1 ). Cumpaclion equipmenl sha ll be adequately sized and be either specifically designed for soil compaction or of proven reliability to efficiently achieve the specified level of compaction with unifom1 ity. 4.4 Compaction of Fill Slopes: In addition to normal compaction procedures specified above, compaction of slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at increments of 3 to 4 feet in fill elevation, or by other methods producing satisfactory results acceptable to the Geotechnical Consultant. Upon completion of grad ing, relative compaction of the fill, out to the slope face, shall be at least 90 percent of maximum density per ASTM Test Method D 1557-91. 4.5 Compaction Testing: Field tests for moisture content and relative compaction of the fill soil s shall be performed by the Geotechnical Consultant. Location and frequency of tests shall be at the Consultant's discretion based on field conditions encountered. Compaction test locations will not necessarily be selected on a random basis. Test locations shall be selected to verify adequacy of compaction levels in areas that are judged to be prone to inadequate compaction (such as close to slope faces and at the fill/bedrock benches). Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS PageS of 6 4.6 Frequency of Compaction Testing: Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of compacted fill soils embankment. In addition, as a guideline, at least one test shall be taken on slope faces for each 5,000 square feet of slope face and/or each I 0 feet of vertical height of slope. The Contractor shall assure that fill construction is such that the testing schedule can be accomplished by the Geotechnical Consultant. The Contractor shall stop or slow down the earthwork construction if these minimum standards are not met. 4.7 Compaction Test Locations: The Geotechnical Consultant shall document the approximate elevation and horizontal coordinates of each test location. The Contractor shall coordinate with the project surveyor to assure that sufficient grade stakes are established so that the Geotechnical Consultant can determine the test locations with sufficient accuracy. At a minimum, two grade stakes within a horizontal distance of I 00 feet and vertically less than 5 feet apart from potential test locations shall be provided. 5.0 Subdrain Installation Subdrain systems shall be installed in accordance with the approved geotechnical report(s), the grading plan, and the Standard Details. The Geotechnical Consultant may recommend additional subdrains and/or changes in subdrain extent, location, grade, or material depending on conditions encountered during grading. All subdrains shall be surveyed by a land surveyor/civil engineer for line anJ grade afler installation and prior lo burial. Sufficieul lillle should be allowed by the Contractor for these surveys. 6.0 Excavation 3030.1094 Excavations, as well as over-excavation for remedial purposes, shall be eva luated by the Geotechnical Consultant during grading. Remedial removal depths shown on geotechnical plans are estimates only. The actual extent of removal shall be determined by the Geotechnical Consultant based on the field evaluation of exposed conditions during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement of materials for construction of the fill portion of the slope, unless otherwise recommended by the Geotechnical Consultant. Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page 6 of 6 7.0 Trench Backfills 3030.1094 7.1 The Contractor shall follow all OHSA and Cai/OSHA requirements for safety of trench excavations. 7.2 All bedding and backfill of utility trenches shall be done in accordance with the applicable provisions of Standard Specifications of Public Works Construction. Bedding material shall have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to 1 foot over the top of the conduit and densified by jetting. Backfill shall be placed and densified to a minimum of 90 percent of maximum from I foot above the top of the conduit to the surface. 7.3 The jetting of the bedding around the conduits shall be observed by the Geotechnical Consultant. 7.4 The Geotechnical Consultant shall test the trench backfi II for relative com paction. At least one test should be made for every 300 feet of trench and 2 feet of fill. 7.5 Lift thickness of trench backfill shall not exceed those allowed 111 the Standard Specifications of Public Works Construction unless the Contractor can demonstrate to the Geotechnical Consultant that the fill lift can be compacted to the minimum relative compaction by his altemative equipment and method. FILL SLOPE PROJECTED PLANE 1 TO 1 MAXIMUM FROM TOE OF SLOPE TO APPROVED GROUND EXISTING GROUND SURFACE FILL-OVER-CUT SLOPE CUT -OVER-FILL SLOPE PROJECTED PLANE 1 TO 1 MAXIMUM FROM TOE OF SLOPE TO APPROVED GROUND KEYING AND BENCHING 15' MIN. LOWEST BENCH (KEY) -----------------· ----------------------------------------------------------- REMOVE UNSUITABLE MATERIAL REMOVE UNSUITABLE MATERIAL REMOVE UNSUITABLE MATERIAL CUT FACE SHALL BE CONSTRUCTED PRIOR TO FILL PLACEMENT FOR SUBDRAINS SEE STANDARD DETAIL C BENCHING SHALL BE DONE WHEN SLOPE'S ANGLE IS EQUAL TO OR GREATER THAN 5: 1. MINIMUM BENCH HEIGHT SHALL BE 4 FEET AND MINIMUM FILL WIDTH SHALL BE 9 FEET. GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAILS A LEIGHTON AND ASSOCIATES • OVERSIZE ROCK IS LARGER THAN 8 INCHES IN LARGEST DIMENSION. FINISH GRADE • EXCAVATE A TRENCH IN THE COMPACTED FILL DEEP ENOUGH TO BURY ALL THE ROCK. GRANULAR MATERIAL TO BE DENSIFIED IN PLACE BY FLOODING OR JETTING. DETAIL • BACKFILL WITH GRANULAR SOI L JETTED OR FLOODED IN PLACE TO FILL ALL THE VOIDS. • DO NOT BURY ROCK WITHIN 10 FEET OF FINISH GRADE. • WINDROW OF BURIED ROCK SHALL BE PARALLEL TO THE FINISHED SLOPE. JETTED OR FLOODED GRANULAR MATERIAL TYPICAL PROFILE ALONG WINDROW OVERSIZE ROCK DISPOSAL GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAILS 8 LEIGHTON AND ASSOCIATES BENCHING OR #2 ROCK (9FTA3/FT) IN FILTER FABRIC SUBDRAIN TRENCH SEE DETAIL BELOW FILTER FABRIC REMOVE UNSUITABLE MATERIAL (MIRAFI 140N OR APPROVED EQUIVALENT)• COLLECTOR PIPE SHALL BE MINIMUM 6" DIAMETER SCHEDULE 40 PVC PERFORATED PIPE. SEE STANDARD DETAIL D FOR PIPE SPECIFICATIONS SUBDRAIN DETAIL DESIGN FINISH GRADE __ -:-::::::::::::::::::::::: 1 0' MIN. _ -_-:-:--=-=-=-=-=-=-=-=-=-=-=-=-= BACK FILL ------------------------· __ -:-::::~.PJ-1P t\_qE;_Q _ fi_L_L:-:-: :-:::::::::-_ F1L TER FABRIC (MIRAFI 140N OR APPROVED EQUIVALENT) •••• .--CAL TRANS CLASS 2 PERMEABLE F=====tt=¢===~==~:::::::::::::::::::==~~;:=::'::::!:::=-OR #2 ROCK (9Fr3jFT) WRAPPED IN FILTER FABRIC 1-----PERFORA TED 1--------------l 6" 0 MIN. PIPE DETAIL OF CANYON SUBDRAIN OUTLET CANYON SUBDRAINS GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAILS C LEIGHTON AND ASSOCIATES OUTLET PIPES 4" 0 NONPERFORA TED PIPE, 100' MAX. O.C. HORIZONTALLY, 30' MAX O.C. VERTICALLY 15' MIN . TRENCH _-_-:::::::::::::~~9~-~~~SJ§_Q_/I~~~}::::::~~ LOWEST SUBDRAIN SHOULD BE SITUATED AS LOW AS POSSIBLE TO ALLOW SUITABLE OUTLET -------------------------------- L I~ KEY WIDTH ·I AS NOTED ON GRADING PLANS KEY DEPTH (15' MIN .) (2' MIN .) 12" MIN. OVERLAP FROM THE TOP HOG RING TIED EVERY 6 FEET T -CONNECTION FOR COLLECTOR PIPE TO OUTLET PIPE CAL TRANS CLASS II PERMEABLE OR #2 ROCK (3 FT~3IFT) WRAPPED IN FILTER FABRIC 4" 0 \~~N-PERFORATED ~T~ ~ ~:c-h~__,~7oi.,jp:;~~:.C: '----4" MIN. BEDDING PROVIDE POSITIVE FILTER FABRIC SEAL AT THE ENVELOPE (M IRAFI JOINT 140 OR APPROVED EQUIVALENT) SUBDRAIN TRENCH DETAIL SUBDRAIN INSTALLATION -subdroin collector pipe shall be installed with perforation down or, unless otherwise designated by the geotechnical consultant. Outlet pipes shall be non-perforated pipe. The subdroin pipe shall hove at least 8 perforations uniformly spaced per foot. Perforation shall be 1 I 4" to 1 12" if drill holes ore used. All subdroin pipes sholl hove a grodien t of at least 2% towards the outlet. SUBDRAIN PIPE -Subdroin pipe shall be ASTM D2751, SDR 23.5 or ASTM D1527, Schedule 40, or ASTM D3034, SDR 23.5, Schedule 40 Polyvinyl Chloride Plastic (PVC) pipe. All ou tlet pipe shall be placed in a trench no wide than twice the subdroin pipe. Pipe shall be in soil of SE >I= 30 jet ted or flooded in place except for the outside 5 feet which shall be native soil bock fill. BUTIRESS OR REPLACEMENT FILL SUBDRAINS GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAILS D LEIGHTON AND ASSOCIATES RETAINING WALL WALL WATERPROOFING ~ PER ARCHITECT'S SPECIFICATIONS FINISH GRADE ·-----------------------------------------------------------------------------------------------------------·:-:-:-:-:-:-:-:-:-:-:-:-:-coMPACTED Fl LL --:-:-:-:-:-:-: ------------------------------------------------------------------·---------------------------- WALL FOOTING-- SOIL BACKFILL, COMPACTED TO 90 PERCENT RELATIVE COMPACTION BASED ON ASTM D1557 -----------------------------::::::::::::::::::::::::::: j ~-;-: -.r-~~~=== :::::::::--. -----------------------------------------_ -_ -----.. ------------------------ ( 0 ° 0 • 01 ~~;:~{ • • 0 0 -:-:-:-:· I 1' MIN. 1::::::::: 3/4" TO 1-1/2" CLEAN GRAVEL 0. 0 : z------ 1·0 :oSI{i--------4" (MIN.) DIAMETER PERFORATED ~ 0 1 -:z PVC PIPE (SCHEDULE 40 OR I . 00 0 .' ::::::::: EQUIVALENT) WITH PERFORATIONS 06£: -:-:-:-:-ORIENTED DOWN AS DEPICTED I 0 0 • 0 I::::::::: MINIMUM 1 PERCENT GRADIENT ~ o 0 ::::::::: TO SUIT ABLE OUTLET L: _· ::-:-:-=· 3" MIN. COMPETENT BEDROCK OR MATERIAL AS EVALUATED BY THE GEOTECHNICAL CONSULTANT NOTE : UPON REVIEW BY THE GEOTECHNICAL CONSULTANT, COMPOSITE DRAINAGE PRODUCTS SUCH AS MIRADRAIN OR J-DRAIN MAY BE USED AS AN ALTERNATIVE TO GRAVEL OR CLASS 2 PERMEABLE MATERIAL. INSTALLATION SHOULD BE PERFORMED IN ACCORDANCE WITH MANUFACTURER'S SPECIFICATIONS. RETAINING WALL DRAINAGE DETAIL GENERAL EARTHWORK AND GRADING SPECIFICATIONS STANDARD DETAILS E LEIGHTON AND ASSOCIATES I I I I I I I I I I I