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Home My WebLink About4850373-02; Calavera Hills Park Geotechnical Investigation; Calavera Hills Park Geotechnical Investigation; 1985-07-24LEIGHTON and ASSOCIATES INCORPORATED ,.rrl n I & SOIL ENGINEERING GEOLOGY GEOPHYSICS GROUND WATER HAZARDOUS WASTES GEOTECHNICAL INVESTIGATION CALAVERA HILLS PARK SITE CARLSBAD, CALIFORNIA July 24, 1985 Project No. 4850373-02 Prepared for: CITY OF CARLSBAD Parks and Recreation 1200 Elm Avenue Cnrlsbad, California 92008-1989 Attention: Mr. Dave Bradstreet 4393 VIEWRIDGE AVENUE, SUITE D, SAN DIEGO, CALIFORNIA 92123 IRVINE • WESTLAKE/VENTURA;• DIAMOND (JAR/WALNUT * SAN BERNARDINO/RIVERSIDE PALM DESERT • SANTA CLARITA/VALENCIA (619) 292-8030 • (800) 253-4567 SAN DIFGO LEIGHTON and ASSOCIATES INCORPORATED SOIL ENGINEERING GEOLOGY GEOPHYSICS GROUND WATER HAZARDOUS WASTES July 24, 1985 Project No. 4850373-02 TO: City of Carlsbad Parks and Recreation 1200 Elm Avenue Carlsbad; California 92008-1989 ATTENTION: Mr. Dave Bradstreet SUBJECT: Geotechnical Investigation, Calavera Hills Park Site, Carlsbad, California In accordance with our proposal dated March 29, 1985, we have performed a geotechnical investigation of the soil and rock conditions within the proposed Calavera Hills Park Site. The accompanying report presents the findings, conclusions, and recommendations of our investigation. . If you have any questions regarding our report, please do not hesitate to contact this office. We appreciate this opportunity to be of service. Respectfully submitted, ,EIGHTON AND ASSOCIATES, INC. Ernest R. ArtSm, CEG 1084 Chief Engineering Geologist Avram Ninyo, RCE 29538 Manager/Chief Geotechnical Engineer RLW/SJ/AG/EA/AN/ea Distribution: (2) Addressee (2) RSI Attention: Mr. Steve Lang (2) Rick Engineering Attention: Mr. Bob Ladwig 4393 VIEWRIDGE AVENUE, SUITE D, SAN DIEGO, CALIFORNIA 92123 (619) 292-8030 • (800) 253-4567 IRVINE WESTLAKE/VENTURA DIAMOND BAR/WALNUT SAN BERNARDINO/RIVERSIDE SAN DIEGO PALM DESERT • SANTA CLARITA/VALENCIA 4850373-02 TABLE OF CONTENTS Section 1.0 INTRODUCTION I.I Purpose and Scope 2.0 PROPOSED DEVELOPMENT 3.0 SITE LOCATION AND DESCRIPTION 3.1 Site Location 3.2 Site Description 3.3 Site Development 4.0 SUBSURFACE EXPLORATION 4.1 Exploratory Trenches 4.2 Seismic Refraction Survey 4.2.1 Geologic Interpretation of Geophysical Data 5.0 GEOLOGY 5.1 Geologic Setting 5.2 Site Geology 5.2.1 Pre-Cretaceous Metavolcanics (map symbol - pkm) 5.2.2 Alluvium (map symbol - Qal) 5.2.3 Artificial Fill and Debris (map symbol - FHI) 5.3 Ground Water 5.4 Faulting, Seismicity, and Liquefaction 5.4.1 Faulting 5.4.2 Seismicity 5.4.3 Liquefaction 6.0 CONCLUSIONS 7.0 RECOMMENDATIONS 7.1 Slope Stability _. . _, 7.1.1 Deep-Seated Stability 7.1.2 Surficial Slope Stability 7.2 Rippability 7.3 Earthwork Page I 3 3 3 3 4 4 4 6 6 6 6 7 7 7 8 8 8 8 9 10 10 10 10 10 II yf JLJ LEIGHTON and ASSOCIATES INCORPORATED I I I I fl I i • 1 4850373-02 TABLE OF CONTENTS (Cont'd.) Section 73.1 Site Preparation 73.2 Excavations 733 Fills 73.4 Oversize Material 73.5 Removal and Recompaction 73.6 Grading of Expansive Soils 73.7 Lot Capping 73.8 Transition Lots 73.9 Shrinkage and Bulking 73.10 Subdrains 73.11 Slope Drainage 73.12 Trench Excavations and Backfi II 7.4 Foundation and Slab Design 7.4ol Foundations 7.4«,2 Floor Slabs 7.4.3 Design for Expansive Soil 1 7.5 7.6 7.7 7.8 7.9 7.10 Lateral Earth Pressures Type of Cement for Construction Surface Drainage Graded Slopes Pavement Design Construction Observation Page 12 12 12 13 13 13 13 13 14 14 14 14 15 15 15 16 16 16 16 16 LIST OF ILLUSTRATIONS 1 *I I I 1 i 1 Figures Figure I - Site Location Map Figure 2 - Fault Location Map Figure 3 - Geologic Cross Section A-A' Figure 4 - Geologic Cross Section B-B1 Tables Table I - Seismic Parameters for Active Faults Table 2 - Seismic Refraction Survey Summary of Results Table 3 - Foundation and Slab Recommendations for Expansive Soils Plate Plate I - Geotechnical Map Rear of Text Rear of Text Rear of Text Rear of Text Rear of Text Rear of Text In Pocket LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 TABLE OF CONTENTS (Cont'd.) APPENDICES Appendix A - References Appendix B - Trench Logs Appendix C - Seismic Refraction Survey Appendix D - Sampling and Laboratory Procedures Appendix E - General Earthwork and Grading Specifications 'CS-a» in JLJ LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 . • 1.0 INTRODUCTION I.I Purpose and Scope This report has been prepared at your request and written authorization in accordance with our proposal dated Novembers, 1984. Our report presents the results of our geotechnical investigation of the proposed Calavera Hills Park. The purpose of our investigation was to evaluate the on-site geotechnical conditions and provide conclusions and recommendations relative to the proposed development. Our scope of services included the following: • Review of available pertinent, published and unpublished geologic literature (Appendix A - References). • Aerial photographic analysis to assess the general geology and the possible presence of ancient landslides and faulting (Appendix A). • Geologic mapping of natural exposures of the geologic units within and adjacent to the project. • Subsurface exploration consisting of seven backhoe trenches and three seismic refraction traverses. • Laboratory testing of representative undisturbed and bulk soil samples obtained from the subsurface exploration program (Appendix D). • Analysis of field data, laboratory test results, aerial photographic interpretation, and preparation of geotechnical maps. • Preparation of this report presenting our findings, conclusions, and recommenda- tions with respect to the proposed development. 2.0 PROPOSED DEVELOPMENT Based, on the information currently available, development at the site includes construc- tion of building pads, roadways, and slopes for a proposed community center/park site. Detailed grading plans were not available at the time of this report. Recreation Systems Incorporated has provided a 40-scale map, Master Plan, Calavera Hills Community Park, City of Carlsbad, dated April I, 1985. Review of this map indicates that slopes are proposed at slope ratios of 2:1 (horizontal to vertical). Grading of the site will require fill up to approximately 35- feet above existing grades. The maximum anticipated fill slope height in the southern portion of-the site area is approximately 25- feet. Cut slopes, b:;scd on reivew of the aforementioned map, are not anticipated to exceed approximately 35ifeet. LJLJ LEIGHTON and ASSOCIATES INCORPORATED -fc^^'; T "-^ ~ T&W^r'-^?'^ t\ ^ ,'"• ••-"-••, ' 'Viwaiaon - .. ~-^-4— -""/Parli' ''• JJ [7 '^'-'A Trailefv ''i -- •' • " • T\ ' '• " •-• II V 5 ' BASE MAP: San Luis Rey 15' Quadrangle, California _ San Diego Co. 7.5 Minute Series (topographic) 2000 4000 , scale feet RSI / CALAVERA HILLS PARK CARLSBAD, CALIFORNIA Figure 1 SITE LOCATION MAP Project No. 4850373-01 Page 2 LJU LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 3.0 SITE LOCATION AND DESCRIPTION 3.1 Site Location The subject site is located in Carlsbad, California, southeast of the intersection of Tamarack Avenue and Elm Avenue (see Site Location Map, Figure I). More specifically, the site is bounded to the.north by Elm Avenue, on the east by Glasgow Drive, on the west by Tamarack Avenue, and on the south by the "Colony at Calavera Hills, Village B" residential subdivision (Map No. 9935). 3.2 Site Description . -, The irregular-shaped parcel encompasses approximately 14 acres and is bisected by a northeasterly-trending, 34-foot wide, temporary access easement. Topographi- cally, the site can be considered the western portion of a ridgetop, with drainage to the north, west, and south. Two major drainage courses are present on site, one a north-trending canyon which crosses the northern property boundary and the other a west-trending canyon paralleling the southern property boundary. Relief across the site is approximately 90 feet, with elevations ranging from 270- near the southwest property corner to 360- near the eastern central property boundary. Natural hillsides vary from approximately 10:1 (horizontal to vertical) to approximately 2:1 (hori- zontal to vertical) along the sides of the aforementioned canyons. Surface drainage, in general, is toward the west and north along the canyons near the northern and southern portions of the subject site, respectively. Localized surface drainage of the hillsides follows the present slope gradient. Vegetation on site consists of grasses, high weeds, and large, mature eucalyptus trees which are locally very dense. 3.3 Site Development Development on site consists of an equestrian underpass, a water tank, wire fences, construction sheds, and utility and waterline easements. The site is locally underlain by areas of dumped debris fill (see Geotechnical Map, Plate I). Cut slopes have been constructed along the edge of Tamarack Avenue and along a temporary access road which bisects the site. These slopes were graded by Chilcote, Inc. in conjunction with the construction of Tamarack Avenue and the temporary access road. Cut slope inclinations are approximately 2:1 (horizontal to I vertical). Communication with Mr. Doyle Brewer of Chilcote, Inc. indicates that the existing cuts were constructed utilizing only heavy-duty grading equipment and that blasting was not required to reach the existing grades. Mr. Brewer also noted, however, that in adjacent-areas, blasting was necessary to reach equivalent .elevations. In either case, the materials generated were generally rocky with little or no "soil-like" material produced.. '§ LJJ LEIGHTON and ASSOCIATES INCORPORATED i Ii FiIi i i i i i i i i i i 4850373-02 . 4.0 SUBSURFACE EXPLORATION Our subsurface exploration program consisted of seven exploratory backhoe pits and subsurface exploration utilizing seismic refraction techniques. A summary of our field exploration is presented in the following sections. 4.1 Exploratory Trenches Seven exploratory trenches were excavated with a backhoe during our geotechnical investigation for the proposed park site. The trenches were excavated to evaluate the conditions of alluvium, fill, and underlying bedrock. - The excavations were logged by a geologist from our firm. Bulk samples were obtained at frequent intervals for laboratory testing. Also, two sand-cone density tests (ASTM DI556-82) were taken in exploratory Trench T-l in order to evaluate shrinkage and bulking potential of the alluvial soils. Logs of the exploratory trenches excavated during our geotechical investigation are presented in Appen- dix B. The approximate locations of the test excavations are indicated on the Geotechnical Map (Plate I). 4.2 Seismic Refraction Survey Our seismic refraction survey consisted of three seismic refraction traverses (normal and reverse) performed in selected areas of the subject site. The seismic refraction survey was performed to evaluate excavatability characteristics of the metavolcanic bedrock underlying the site. The details of the field operations, equipment, data reduction, and method of interpretation are presented in Appen- dix C. 4.2.1 Geologic Interpretation of Geophysical Data The corrected geophysical data along Line I (Appendix C) are interpreted to indicate two layers. The upper layer (2,500 to 3,750 ft./sec.) is interpreted geologically as weathered, metavolcanic bedrock approximately 6 feet thick. The lower layer (12,500 ft./sec.) is interpreted geologically as rela- tively unweathered, metavolcanic bedrock. The geophysical data along Line 2 (Appendix C) are interpreted to indicate two layers. The upper layer is interpreted geologically as residual soil (2,300 to 2,500 ft./sec.) and weathered, metavolcanic bedrock (4,300 f t./sec.) approximately 6 feet thick. The lower layer (7,000 to 8,500 ft./sec.) is interpreted geologically as relatively unweathered, meta- volcanic bedrock. The geophysical data along Line 3 (Appendix C) are interpreted to indicate three layers., The upper layer (1,250 to 1,500 f t./sec.) is interpreted geo- logically as residual soil approximately 0 to 5 feet thick which pinches out at the northwest end of the survey line. Underlying this layer is a higher velocity zone (3,000 to 4,500 ft./sec.) which is interpreted geologically as weathered, metavolcanic bedrock approximately II to 20 feet thick. The i -4-LJLJ LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 I deepest layer (8,000 ft./sec.) is interpreted geologically as relatively un- weathered, metavolcanic bedrock. From the data obtained, observations of actual bedrock outcrops, and variable subsurface characteristics of the metavolcanic bedrock, the higher velocity bedrock surface is irregular with many weathered zones between occasional resistant zones of relatively unweathered bedrock. I I I I I I I I ! 1 I I -5- ^go LJLJ LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 . 5.0 GEOLOGYg ' \ 5.1 Geologic Setting B The subject site is located in the Peninsular Range Province, a California physio- , graphic province with a long and active history in southern California. The i Peninsular Range Province is characterized by northwest-trending mountain ranges • separated by subparallel fault zones. The mountain ranges are underlain by .basement rocks consisting of Jurassic metavolcanic and metasedimentary rocks and Cretaceous igneous rocks of the southern California batholith. Late Cretaceous, Tertiary, and Quaternary sediments flank the mountain ranges to the northeast and southwest. Intrusion of the batholithic rocks occurred during the Cretaceous period. The batholithic rocks intruded pre-exisMng, Jurassic-aged metasedimentary and meta- volcanic rocks. Uplift and erosion since Cretaceous time has resulted in removal of large volumes of the Jurassic metamorphic rocks and has exposed large areas of the Cretaceous igneous rocks. The Upper Cretaceous, Tertiary, and Quaternary rocks flanking the southwestern margin of the mountains are generally comprised of detrital marine, lagoonal, and nonmarine sediments consisting of sandstones, mudstones, and conglomerates. These sedimentary formations are generally flat-lying or dip gently to the south- west, except for locally deformed areas such as Mount Soledad and La Jolla (approximately 17 miles southwest of the site). The Peninsular Range Province is traversed by several major active faults (refer to Figure 3). The Elsinore and San Jacinto faults (associated with the San Andreas fault system) are the major tectonic features. Both are strike-slip faults with predominantly right-lateral movement. The major tectonic activity appears to be a result of right lateral movement on faults within the San Andreas fault system. 5.2 Site Geology Field exploration and aerial photo analysis indicate the site is underlain by pre- Cretaceous metavolcanic rocks. These are mantled by alluvium, fill, debris, and residual soils of variable thickness. The site-specific geology is depicted on the Geotechnical Map, Plate I, and Geologic Cross Sections A-A' and B-B1, Figure 3 and 4, respectively. The following is a description of the various units. 5.2.1 Pre-Cretoceous Metavolcanics (map symbol - pkm) Our subsurface explorations and field mapping indicate that the entire subject site is underlain by pre-Cretaceous metavolcanics. The pre- Cretaceous metavolcanic rocks are slightly metamorphosed volcanic and volcaniclastic rocks of variable composition and color. These rocks are very dense and resistant to weathering and, erosion. As encountered in our investigation, the rocks are highly jointed and fractured. The metavolcanic bedrock encountered at the site is highly fractured and jointed. Generally, fracture spacing ranges from less than I inch to over I foot. The rock fractures and joints dip steeply (generally 40 to 90 degrees) and have omnidirectional trends. -6- ^5"»- UU LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 I I I I I I I I I As exposed in the cut slopes along the temporary access easement and in our excavations, some of the joints in the near-surface weathered rock zone are open and coated with residual clay, manganese oxide, and iron oxide. The metavolcanic rock is mantled with a thin veneer of residual topsail. These surficial soils consist of orange to orange-brown to red-brown to brown-gray to brown, medium dense to dense, silty sand. These soils are derived from weathering of the metavolcanic bedrock and range from zero to less than 5.0-feet thick. Based on laboratory testing, we anticipate that the residual soils will have a low to moderate expansion potential. 5.2.2 Alluvium (map symbol - Qal) • — Alluvial soils were encountered in the exploratory trenches along the alignment of the west-trending canyon paralleling the southern property boundary. The alluvium, as observed, can be generally classified into two groups. The first consists of green-brown to medium brown to dark red- brown, moist to wet, loose to medium dense, silty fine to medium sand. The second type consists of dark brown, moist to wet, soft,-fine, sandy silt. The alluvium was observed to a maximum depth of approximately 9 feet. The alluvium is anticipated to be reusable as fill material after moisture conditioning. Based on our observation and visual classification, we anticipate the alluvium will exhibit low to moderate expansion characteris- tics. The in-place alluvium has significant potential for consolidation. 5.2.3 Artificial Fill and Debris Fill (map symbol - Fill) A man-made fill slope laps against the eastern edge of Tamarack Avenue near the southeast portion of the site. This fill appears to have been constructed during the construction of Tamarack Avenue and modified by the construction of the equestrian underpass and is assumed to be a docu- mented structural fill. The fill soils observed generally consist of light brown, silty sands. Two portions of the site are underlain by end dumped fill and debris fill and designed as "debris fill" on the attached Geotechnical Map (Plate I). This debris fill consists of various amounts of different soils, construction debris, vegetation, and trash. These materials are not reusable as fill materials and should be completely removed from the site prior to the commencement of grading. Ground Water No surface water was observed on site during our investigation. The exploratory Trench T-2 indicates that the water table elevation in the alluvial area in the canyon near the southern portion of the site was approximately 268 feet at the time of the excavation. Seasonal fluctuation in rainfall,, variations in ground surface topography, and subsurface stratification may significantly affect surface and ground water levels. -7- <4M» LJU LEIGHTON and ASSOCIATES INCORPORATED I I I I i I I iI ][ i]i 4850373-02 5.4 Faulting, Seisrnicity, and Liquefaction 5.4.1 Faulting A review of available geologic literature pertaining to the subject site indicates that there are no known -active faults crossing the property. Further, there was no evidence of faulting encountered during our investiga- tion. The nearest major active fault is the Coronado Banks fault located approximately 17 miles to the southwest. Figure 2 indicates the location of the site in relationship to known major faults in the San Diego region. 5.4.2 Seismicity . -»• The seismic hazard most likely to impact the subject site is ground shaking following a large earthquake on one of the major active faults. Table.I indicates probable seismic events that could produce ground shaking at the study area. Included in the table are the distance to the faults, maximum credible and probable earthquakes, and the expected peak hori- zontal bedrock accelerations. The Coronado Banks fault 5s the fault most likely to affect the site with ground shaking should an earthquake occur on the fault. A maximum probable event on the Coronado Banks fault could produce a peak horizontal bedrock acceleration of approximately 0.18g. For design purposes, two- thirds of the maximum anticipated bedrock acceleration may be assumed for design ground acceleration. The effect of seismic shaking can be mitigated by adhering to the Uniform Building Code or state-of-the-art seismic design parameters of the Structural.Engineers Association of California. 5.4.3 Liquefaction Liquefaction and dynamic settlement of soils can be caused by strong vibratory motion due to earthquakes. Both research and historical data indicate that loose, granular soils are susceptible to liquefaction and dynamic settlement while the stability of silty clays and clays is not adversely affected by vibratory motion. Liquefaction is typified by a total loss of shear strength in the affected soil layer, thereby causing the soil to flow as a liquid. This effect may be manifested by excessive settlements and sand boils at the ground surface. The bedrock at the site is not considered liquefiable due to its very high density characteristics. Alluvial material designated as Qal on Plate I varies laterally from silts (Trench T-2) to silty sands (Trenches T-1 and T-2). Although precise lateral limits of each type of material cannot be determined without further subsurface investigation, it appears that the majority of the alluvium consists of relatively loose, granular soils (silty sands). Therefore, the alluvium should be considered as potentially liquefiable in all design considerations. Mitiga- tive measures are presented in Section 8.3.5, Removal and Recompaction. tar LJLJ -8- LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 6.0 CONCLUSIONS Based on the results of our preliminary geotechnical investigation of the site, it is our opinion that the proposed development is feasible from a geotechnical standpoint, provided that the following conclusions and recommendations are incorporated into the project plans and specifications. The following is a summary of the geotechnical factors which may affect development of the site. • Our investigation indicates that much of the site Is underlain at depths of approxi- mately 5 to 20 feet by nonrippable earth materials which will require drilling and blasting prior to excavation. Nonrippable materials present at finish grades will impact trenching and other related construction operations. Oversize materials generated during construction will require special handling and/or disposal methods. • The presence of nonrippable materials at shallow depths limits the quantity of soil-like material available on site for construction. • Compressible alluvium is present in the southern portion of the site. We anticipate remedial grading measures such as remova^ and recompaction or other techniques will be necessary to mitigate this condition. -9- >e» LJU LE1GHTON and ASSOCIATES INCORPORATED 1 I 5 Ii I I Iii i 1 1 *I I I I i 4850373-02 7.0 RECOMMENDATIONS 7.1 Slope Stability 7.1.1 Deep-Seated Stability Our analysis generally indicates that the proposed slopes will be stable, with respect to deep-seated stability, to the proposed heights at slope ratios of 2; I (horizontal to vertical), in the absence of adverse geologic conditions. 7.1.2 Surficial Slope Stability Based on experience with similar materials on adjacent sites, we anticipate that the constructed slopes will demonstrate acceptable factors of safety as related to surficial stability. Erosion and/or surficial failure potential of fill slopes may be reduced if the following measures are implemented during design and construction of the subject slopes. • Selective Grading of Fill Materials We recommend against the exclusive use of either highly expansive, clayey soils or poorly graded sands in the face of fiJI slopes. Highly expansive soils are generally known to be subject to surficial failures when exposed in slope faces. Poorly graded sands utilized in slope faces may be subject to excessive erosion and rilling. A thorough mixture of clayey-fill soils with on-site sands is recommended to reduce overall expansion potential and slope erosion. We recommend that mixture of soils be approved by the project geotechnical engineer prior to place- ment in fill slopes. • Slope Landscaping and Drainage Cut and fill slopes should be provided with appropriate surface drainage features and landscaped with drought-tolerant, slope-stabilizing vegeta- tion as soon as possible after grading to minimize potential for erosion. Berms should be provided at the top of all slopes and lot drainage directed such that surface runoff on slope faces is minimized. 7.2 Rippability Based on the results of. our.-field investigation, it appears.that much of the site is , underlain by very dense metamorphic rocks which will be difficult to excavate. The results of our investigation indicate that, generally, excavations in these areas greater than 5 to 10 feet deep will encounter nonrippable material. (Nonrippable material is considered that which is not economically ripped by a CAT D-9H with a single shank ripper.) The depth to the nonrippable material will vary at locations on site, but it appears that 5 feet is an average depth to the nonrippable material for much of the site. \g-Bf uuH- 10- LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 : . ; We anticipate that significant amounts of oversized material will be generated during excavation in the work areas. Recommendations for treatment of the oversize material are included in the attached General Earthwork and Grading Specifications, Appendix E. In addition to creating an additional cost factor during mass grading, the nonrippable material will impact the excavation of utility trenches, foundation excavations, and create irregular cut slopes and finish pads which will pose difficult landscape conditions. In rock areas, it may be economical to undercut street and building pad areas to a depth below proposed utility foundation depths with replacement of compacted fill rather than try to deal with the rock during utility trench and foundation excavation. If undercutting or replacement of the rock is implemented, we would suggest that the undercut be to a depth 9f,2feet below the bottom of proposed utilities and/or foundations. 7.3 Earthwork Grading and earthwork should be performed in accordance with the following recommendations and the General Earthwork and Grading Specifications included in Appendix E. Grading should be observed and fill tested by the geotechnical engineer. Final grading plans and specifications should be thoroughly reviewed by the geotechnical engineer to see if additional earthwork recommendations are needed. 7.3.1 Site Preparation Prior to grading, the site should be cleared of surface and subsurface obstructions, including any existing debris and buried utilities, and stripped of vegetation. Removed vegetation and debris should be disposed of off site or used in nonstructural landscape areas. Holes resulting from removal of buried obstructions which extend below finished site grades should be filled with compacted soil. 7.3.2 Excavations Based on our visual observations of the bedrock materials on the site, our trenching and seismic profiling on site, and our experience with bedrock materials on similar and adjacent sites, we have the following estimates of rippability: • Surficial soils and alluvial deposits may be excavated by conventional construction,equipment. • Excavations into the weathered zones of the metamorphic rocks may be accomplished by the use of heavy-duty construction equipment. The metamorphic bedrock underlying the weathered layers will most likely require blasting. Oversize material may be generated if "floaters" are encountered or during ripping of the weathered bedrock soils. Our estimate is that the depth to the base of the weathered bedrock soils is vg«> JLJ LEIGHTON and ASSOCIATES INCORPORATED I i j j 4850373-02 I I i I I i on the order of 5 to 6 feet with nonrippable bedrock encountered as shallow as 2 feet below the existing ground surface in some areas. 7.3.3 Fills The on-site soils are generally suitable for use as compacted fill provided they are free of organic material and debris. 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 D1557-78). Fill should generally be placed in uniform lifts not exceeding 8 inches. The optimum lift thickness to produce a uniformly.compacted fill will depend on the size and type of construction equipment utilized. Fill materials that contain less than optimum moisture content should be moisture conditioned to bring the fill up to optimum moisture prior to fill placement. Near- surface fill soils at the building pad grades should be predominantly granular, nonexpansive, and approved by the geotechnical engineer. Fills placed on natural slopes steeper than 5:1 (horizontal to vertical) should be keyed and benched into firm formational units. Hard rock outcrops may require special care in fill compaction. To minimize possible differential settlement in these areas, we recommend that fills placed adjacent to hard rock outcrops be given special attention. In general, placement of fill should be performed in general accordance with local grading ordinances, sound construction practice, and the General Earthwork and Grading Speci- fications presented in Appendix E. 7.3.4 Oversize Material Excavations in the bedrock materials will likely produce oversize rock materials. Such materials will require special handling as described in Appendix E and utilization of sound field construction practice. The experience and field judgement of the geotechnical consultant should be utilized in placement of oversize material. Some oversize material may be placed in the heads of drainages to act as energy dissipators of heavy runoff and to minimize erosion in these drainages. Oversize material may also be utilized as landscape or "natural" rock in green belt areas. 7.3.5 Removal and Recompaction All topsails, compressible alluvium, and all undocumented fill soils not removed by the planned grading should be excavated, moisture conditioned, and then compacted prior to placing any additional fill. The residual and alluvial soils that occur on site are potentially compressible in their present state and may settle appreciably under the surcharge of fills or foundation loadings. In areas that will receive fill or other surface improvements, these soils should be removed down to competent materials and recom- pacted. In general, we estimate that the average alluvial removal is on the order of 5 to 10 feet. Residual topsails across the site are on the order of 0 to 3 feet thick. These depths may be modified based on our geotechnical observations during grading. v&" LJLJ - I 2 - LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 I 7.3.6 Grading of Expansive Soils We recommend that expansive soils encountered during grading operations be placed in fill areas below a minimum depth of 3 feet measured from finished grade, and not within 15 feet of the face of any slope. If expansive soils are placed within the upper 3 feet of pad grade, special foundation design recommendations for expansive soils (in accordance with Sec- tion 8.^.3) should be implemented. Our evaluation indicates that most of the earth materials observed on site will exhibit low expansion potential. 7.3.7 Lot Capping It is recommended that all cut pads exposing unsuitable materials such as highly fractured or weathered bedrock or residual topsoil and the cut portions of transition lots (due to proposed cut/fill grading or recommended ; remedial work), be overexcavated q minimum depth of 3 feet and to a minimum distance of 5 feet outside building areas and replaced with compacted fill. Based on in-grading inspection, localized deeper over- excavation and recompaction of the unsuitable soils may be required. 73.8 Transition Lots To minimize the potential for differential settlements, the entire cut portions of areas planned for structures on daylight lots should be over- excavated to a minimum depth of 2 feet below the bottoms of proposed foundations and replaced with properly compacted fill. The overexcavation should laterally extend at least 5 feet beyond the building pad area. If possible, buildings should be located so as to avoid cut/fill transitions. 7.3.9 Shrinkage and Bulking The volume change of excavated on-site materials upon recompaction as embankment fill is expected to vary with materials and location. Based on our limited laboratory testing and our experience with similar materials, the following values are provided as guideline estimates: • Topsoil and Alluvium: 5 to 10 percent shrinkage. • Metavolcdnics: up to 15 percent bulking. 7.3.10 Subdrains To avoid subsurface ground water accumulation, we recommend complete removal of alluvial soils in the bottoms of canyons as determined by the geotechnical consultant. Subdrains should be placed in the canyon bottoms in accordance with the design provided in the accompanying General Earthwork and Grading Specifications, Appendix E. Recommendations to minimize possible water seepage problems (if any) will be provided during grading. Proposed subdrain locations should be indicated on the grading plan. 1 ULJ- 13-LblUMIUIM INCORPORATED D LEIGHTON and ASSOCIATES 4850373-02 . 7.3.11 Slope Drainage ' In slopes where seepage is present, drainage should be provided as shown in Appendix E. Slopes which may require such special drainage features will be i evaluated and recommendations be provided during grading. 7.3.12 Trench Excavations and Backfill Excavation of trenches in the metavolcanics may be difficult for light backhoes and may locally require the use of heavy-duty trenching equipment • and/or blasting. :. | — The on-site soils may generally be suitable as trench backfill provided they : are screened of organic matter and cobbles over 6 inches in diameter. Hj Trench backfill should be compacted in uniform lifts (not exceeding 8 inches ^1 in compacted thickness) by mechanical means to at least 90 percent relative compaction (ASTM D1557-78). 7.4 Foundation and Slab Design Foundations and slabs should be designed in accordance with the following recom- mendations and the Foundation and Slab Recommendations for Expansive Soils presented in Table 3. We anticipate that slab subgrade conditions will be generally in the low range if on-site soils are utilized for building pad construction. The following presents the minimum recommended design and reinforcement for • foundations and slabs assuming that slabs and foundations will be placed on nonexpansive soils. If expansive soils are encountered or selective grading is not "~ accomplished, design for such conditions may be performed in accordance with ^ Section 8.4.3. These preliminary recommendations are presented for planning and H| budgeting purposes. Final design of foundations and slabs should be based on expansion testing performed at the completion of grading. 7.4.1 Foundations M The proposed residential buildings may be supported by conventional, con- tinuous, or isolated spread footings founded 12 inches for one-story buildings and 18 inches for two-story buildings beneath the lowest adjacent finished grade. Footings should have a minimum width of 12 inches and be reinforced top and bottom with No. 4 rebar. At this depth, footings founded in natural or fill soils may be designed by using an allowable bearing capacity of 2,500 pounds per square foot. This value may be increased by one-third for loads of short duration including wind or seismic forces. The maximum total and differential settlements for footings designed in this manner should be within tolerable limits. R i • - 14- >gxy JLJ LEIGHTON and ASSOCIATES INCORPORATED 4850373-02 . 7.4.2 Floor Slabs Slabs underlain by at least 3 feet of nonexpansive soils should have a minimum thickness of 4 inches and be underlain by a 6-mil Visqueen moisture barrier overlain by a 2-inch layer of clean sand to aid in concrete curing. The moisture barrier should, in turn, be underlain by an additional 2 inches of rounded gravel or sand base. Slabs should be reinforced with 6x6-10/10 welded wire mesh placed at midheight in the slab. 7.4.3 Design for Expansive Soil If selective grading cannot be accomplished so that the slabs are underlain by nonexpansive soil, potential damage to building slabs may be minimized by use of reinforced slabs and presoaking of soils underlying the slabs in accordance with Table 3. Effort should be made to prevent large moisture content variations of the underlying expansive soils by providing positive drainage away from building foundations. Positive drainage may be accom- plished by providing a drainage away from the foundation at a gradient of at least 2 percent for a distance of at least 5 feet. 7.5 Lateral Earth Pressures The recommended lateral earth pressures for the site soils and level or sloping backfill are as follows: Equivalent Fluid Weight (pcf) Condition Level 2:1 Slope Active 40 60 At-Rest 60 90 Passive 300 To design an unrestrained wall, such as a cantilever wall, the active earth pressure may be used. For a restrained retaining wall, such as a basement wall, the at-rest pressure should be used. Passive pressure is used to compute lateral soil resistance developed against lateral structural movement. Further, for sliding resistance, the 1 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 horizontal distance between foundation elements providing passive resistance should be a minimum of three times the depth „, of the elements to allow full development of these passive pressures. All retaining structures should be provided with a .drainage blanket and weepholes or drains (see Appendix E). A surcharge loading effect from adjacent structures should be evaluated by the geotechnical and structural engineers.1 I I 1 -15- LEIGHTON and ASSOCIATES INCORPORATED Ij jl |L i I I I I I (_ , I I I I 1 I 4850373-02 7.6 Type of Cement for Construction Recommendations regarding cement type for use in concrete to be in contact with surface soils will be made based on soluble sulfate content tests to be performed on nearrsurface soils at the completion of grading. 7.7 Surface Drainage Surface drainage should be controlled at all times. Structures should have eave drains and roof gutters to collect roof runoff. Positive surface drainage should be provided to direct surface water away from the structures, toward the street or suitable drainage facilities. Ponding of water should be avoided adjacent to the structures. Area drains should be provided in areas of decking and lawns. We recommend positive drainage away from slopes be maintained. The need for drainage devices on the slopes is within the scope of the design civil engineer. 7.8 Graded Slopes It is recommended that all graded slopes within the development be planted with ground cover vegetation (e.g., grasses) as soon as practical to protect against erosion by reducing runoff velocity and with deep-rooted vegetation (e.g., trees and shrubs) to protect against surficial slumping by providing a deep root mesh. Inadvertent oversteepening of cut and fill slopes should be avoided during the fine grading and construction. 7.9 Pavement Design The appropriate pavement design section depends primarily on the soil shear strength, traffic load, and planned life. R-value testing may be performed during grading to provide an appropriate pavement section. 7.10 Construction Observation The recommendations provided in this report are based on preliminary design information and subsurface conditions disclosed by widely spaced trenches. The interpolated subsurface conditions should be checked in the field during construc- tion. Construction inspection of foundations, subdrains, and field density testing of all compacted fill should a|so be performed by a representative of this office so that construction is in accordance with the recommendations of this report. We recommend that cut slopes be geologically mapped by the geotechnical consultant during grading for the presence of potentially adverse geologic conditions. Final -» project drawings should be checked by Leighton and Associates, Inc. before grading to see that the recommendations provided in this report are incorporated in project plans. ^fj, LJJ •-16- LEIGHTON and ASSOCIATES INCORPORATED i - !i! i! Ill 5 s «?'„: ;s: iSss " i I ci: LU CD COH-_J < LL. UJ> t-U< 01oLu co 01UJ1— LU•^•^< 01< Q. U ^^»CO UJCO •oD-Q ' W ^D U f\\£ • co _M: b CL «omz if oLv <" _g o0 UJ ^< ol £ §£f<fUJ b. iiitII I UJ_l «"•. CO w < °^** rf^CO C0O—n 01 CCu .2 ^?il^- Li. X^<" ^— •5 l^-o ':iiP JQ -t- -D *- AJ= 0 C COX*-' •+" r> ~ % i- *~ '^llj-51--^ nj 0 O U .«=o ,5- T u Oa;^-1-. <cia. •". • <u»- "D0) 3 . . • ; . ^ •— ."5s,';'.— D)cr o :. • - • .. S . '. -- ii\ E«|--u-S''§3'§ ,JJ=-.E =5 ? -c -Fx w£ o §, |u b 'Kg ^ UJ ^ ' <- fl} "^« 0 0 «"«21 W ^i- V7C |, .— (uo "- co — 'ti EosQ OH- —£ ^. a «J- — rvj m oo m— ••—00 0 £** • ' • • • t— ' O O^ O^ <3 O^ o r~ co co r^J r-~ co— — o — o 8 • • • • • . 0 0 0 0 O 0 r^ o rM ro o to• • • • • •vo • . vp • r> • co ' r~ vo in in in m in o• . • • • • •r-~ vo r^co r~» r^ ( ct r^ t^ C2 vo oCM — ^r vo m in "nwoo S v ?c <..•? • £ 'o w o S oCD 0 0 0 £ C o c • £ § £ 3 S' D g- •? 5u b 8 • § -^ '-< §c | -' r^ --S- B ^ 1UJ U co co < Z. VI (D"•»— t/) bu- C_O O1__aj <uo 8J* Di_ _ i.'pCL C D>O*5i rw -S.E b±u_ ? ** TABLE 2 SEISMIC REFRACTION SURVEY SUMMARY OF RESULTS 11 Velocity of Line Layers (ft. /sec.) | 1 2,500 - 3,750 12,500 j 2 2,300 - 4,300 11 • 7,000 - 8,500- 3 3 1,250- 1,500 1 3,000-4,500 Inferred Geologic Materials weathered meta- fresh metavolcanic bedrock residual soil and weathered meta- volcanic bedrock fresh metavolcanic bedrock residual soil weathered meta- Estimated Thickness (ft.) 6 _ 6 — 0-5 11-20 Estimated Depth to Top of Layers (ft.) . 0 6 0 6 0 0-5 Rippability Potentials* D-8 volcan Requires blasting D-8 Marginally rippable with D-IO, may re blasting D-7 D-8 8,000 volcanic bedrock fresh metavolcanic bedrock 20-25 Marginally rippable with a D-IO, may require blasting * Shepherd, 1981, Caterpillar Performance Handbook, ed. II, Caterpillar Tractor Co., Peoria, Illinois, pp. 56-59. 1 - Story Footings I I i 2 - Story footings I ftarage "oor Grade Beam iving Area Floor Slab I I TABLE 3 For Expansive Soils (One- and Two-Story Buildings) Expansion Index 0-20 VERY LOW EXPANSION All footings 12 inches deep. Foot- ings continuous. One No. 4 bar top and bottom. All footings 18 inches deep. Foot ings continuous. One No. 4 bar top and bottom. Expansion Index . 21-50 LOW EXPANSION All footings 12 inches deep. Footings contin- uous. 1-No. 4 bar top and bottom. All footings 18 inches' deep. Footings con- tinuous.. 1-No. 4 bar top and bottom. Optional Reinforce- ment. 8 inches deep 1-No. 4 bar. 4 inches thick. Reinforce with 6x6- 10x10 wire mesh @ mid- height. 6 mil vis- quen noisture barrier. 2 inches of sand or gravel. 12 inches deep 1-No. 4 bar top and bottom. 4 inches thick. 6x6-10/10 wire mesh 0 mid-height 2 inches gravel or sand base. 6 mil visqueen mois- ture barrier plus 1 inch sand. garage I Floor Lsiabs 4 inches thick. Reinforcement with 6x6-10/10 wire mesh @ mid-height or quar- ter slabSc Isolate from stem wall foot- ings. No moisture barrier required. No base required. 'jre-Soak ing Not required. |f Living Moisten prior to •nrea and pouring concrete. Garage llab Soils 4 inches thick. '6x6.-10/10 wire mesh or quarter slabs. Isolate from stem wall footings. 2 inches rock, gravel or sand base. No moisture barrier required. Soak to 12 inches depth to 4% above optimum moisture content. Expansion Index 51-90 MEDIUM EXPANSION Exterior footings 18 inches deep. Interior footings 12 inches deep. 1-No. 4 bar top and bottom. All footings 18 inches deep. Footings continu- ous. 1-No. 4 bar top and bottom. 18 inches deep. 1-No. 4 bar top and bottom. 4 inches thick. 6x6-10/10 wire mesh G> mid-height 4 inches gravel or sand base. 6 mil visqueen mois- ture barrier plus 1 inch sand. 4 inches thick. 6x6-10/10 wire mesh or quarter slabs. Isolate from stem wall footings. 4 inches rock, gravel or sand base. No moisture barrier required. Soak to 18 inches depth to 5% above optimum moisture content. Expansion Index 91 - 130 HIGH EXPANSION Exterior foot- ings 24 inches deep. Interior footings 12 inches deep. 1-No. 5 bar top and bottom. Exterior foot- ings 24 inches deep. Interior footings 18 . inches deep. 1-No. 5 bar top and bottom. 24 inches deep0 1-No. 5 bar top and bottom. 9 4 inches thick* 6x6-6/6 wire mesh @ mid-height No. 3 dowel!s from footing to slab @ 36 inches on center. 4 inches gravel or sand base. 6 mil visqueen moisture barrier plus 1 inch sand. 4 inches thick. 6x6-6/6 wire mesh or quarter slabs. Isolate from stem wall footings. 4 inches rock, gravel or sand base. No mois- ture barrier required. Soak to 24 inches depth to 5% above optimum moisture" content. APPENDIX A 4850373-02 V • APPENDIX A REFERENCES 1. Albee, A.L. and Smith, J.L., 1966, Earthquake characteristics and fault activity in • southern California in Lung R. and Proctor, R., editors, Engineering Geologists-, Special Publication, October. 2. Allen, C.R., Amand, P., Richter, C.F., and Nordquist, J.M., 1965, Relationship between seismicity and geologic structure in southern California: Seis- mological Society of America Bulletin, V. 55, No. 4, p. 753-797. 3. Bolt, B.A., 1973, Duration of strong ground motion: Proc. Fifth World Conference on Earthquake Engineering, Rome, Paper No. 292, pp. 1304-1313, June. 4. Bonilla, M.J., 1970, Surface faulting and related effects in Wiegel, R. (editor), Earthquake Engineering, Prentice-Hall, Inc., New Jersey, pp. 47-74. 5. Cummings, David, I960, Calculation of thickness of "hidden layer" with velocity inversion, shallow refraction surveys, Soc. Exploration Geophysicists. 6. Dobrin, M.B., 1976, Intfoduction to geophysical prospecting: third ed., McGraw-Hill . Book Company, Inc., New York, 630p. 7. Greensfelder, R.W^, 1974, Maximum credible rock acceleration from earthquakes in California: California Division of Mines and Geology, Map Sheet 23. 8. Lamar, D.L., Merifield, P.M., and Proctor, R.J., 1973, Earthquake recurrence intervals on major faults in southern California hi Moran, D.E., Slosson, J.E., Stone, R.O., Yelverton, California, editors, 1973, Geology, seis- micity, and environmental impact: Association of Engineering Geolo- gists, Special Publication. 9. Leighton and Associates, Inc., Unpublished in-house data. . 10. Ploessel, M.R., and Slosson, J.E., September 1974, Repeatable high ground accelera- tions from earthquakes-important design criteria; California Geology, Vol.27, No. 9. 11. Schnabel, B. and Seed, H.B., 1974, Accelerations in rock for earthquakes in the western United States; Bulletin of the Seismological Society of America, Vol. 63, No. 2, pp. 501-516. 12. Seed, H.B., Idriss, I.M.,~and Kiefer, F.W., 1969, Characteristics of rock motions during earthquakes: Journal of Soil Mechanics and Foundations Divi- sions, ASCE, Vol. 95, No. SMS, Proc. Paper 6783, pp. 1199-1218, Septem- ber. 13. Telford, W.M., Geldart, L.P., Sheriff, R.E., and Keys, D.A., 1976, Applied geo- physics, Cambridge University Press, New York, 860p. A-i 4850373-02 APPENDIX A (Cont'd.) 14. Weber, F. Harold Jr., 1.982, Recent slope failures, ancient landslides and related geology of the north-central coastal area, San Diego County, California, • California Division of Mines and Geology, Open File Report 82-12, LAc | 15. Wilson, K.L., 1972, Eocene and related geology of a portion of the San Luis Rey and M Encinitas Quadrangles, San Diego, California. AERIAL PHOTOGRAPHS • Source Flight No. Photo No. Date San Diego County AXN-8M 69,70,102 4-11-53 m and 103 ! I I I I I I I I APPENDIX B MAJOR DIVISIONS 5 col -J»[ COARSE GRAINED SO1 (More Ihan 1/2 ol soil > no. 200*•*o N75 B>£a Wo-Jo 0N COg LJV11 §°ujSz-£s £ 9 O Z GRAVELS (Mora than 1/2 ol coarse fraction > no. 4 eleve elze) SANDS (More than 1/2 of coarse fraction <] no. 4 aleva size) SILTS & CLAYS LL < 60 SILTS & CLAYS LL > 50 HIGHLY ORGANIC SOILS SYMBOL! 'CGW ,<e> •i GP f GM • GC \ •* SW £;• *SP V • i SM : j^/ SC ^ ML CL I OL |:j i MH CH ^X OH ;/•?. _ 3 TYPICAL NAMES >'• :•* Well graded gravels or graveK-aand mixtures, title or no fines .'•• • t' ••Poorly graded gravels or gravel-sand mixtures, little or no fines »:.' | Silly gravala. gravel-sand-allt mixtures ^/ Clayey gravels, gravel-sand-clay mixtures p." *" Well graded aanda or gravelly sands, little or' no fine*»" f ~ Poorly graded sands or gravelly Bands, little or no fine*, • • •• Sllty sands, sand-silt mixtures ?/^Clayey sands, sand-clay mixtures / Inorganic allta and very fine aanda, rock flour, sllty or clayey fine sands or clayey allta with slight plasticity / Inorganic clays of low to medium plasticity, gravelly clays,/,/ sandy clays, sllty clays, lean clays « ii, i Organic silt* and organic sllty clays of low plasticity t i Inorganic silts, micaceous or dlatomaceous fine sandy or silly soils, alaatlc silt* / Inorganic claya of high plasticity, fat clay* '/, Organic clay* of medium to high plasticity, organic sllty claya, rS'y organic silts CLASSIFICATION CHART (Unified Soil Classification System) CLASSIFICATION BOULDERS COBBLES GRAVEL coarse fine SAND coarse medium line SILT & CLAY RANGE OF GRAIN SIZES U.S. Standard Sieve Size Above 12" 12" to 3" 3" to No. 4 »" to S/4" 9/4" (0 No. 4 No. 4 to No. 200 NO. 4 to No. 10 No. 10 10 Ho. 40 No. 40 10 No. 200 Below No. 200 Grain Size In Millimeters Above 305 305 to 76.2 76.2 to 4.76 Te.a to is.i ie.i to 4.7* 4.76 to 0.074 4.7* 10 t.OO t.OO 10 0.410 0.420 10 0.074 Below 0.074 ou 111aZ 40 > "-.„ 2 H <20 Ja. 0 CL-f ."XML 1 'k OL C ,. /^ H ^1 ni' x i x X 0 10 20 SO 40 SO SO 70 SO SO 100 LIQUID LIMIT PLASTICITY CHART GRAIN SIZE CHART METHOD OF SOIL CLASSIFICATION LOG OF TRENCH".NO:__22:L inUJI—I OS UJ O. §C. o 1—4a UJ UJ sUJ Density (I Compaction) Moisture Sample No. U.S.C.S. ^6?.Project Numberu 1 Q. 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JO t g M -V " x - ctr C g jvr VJ 0 <8> 1 111 vi B01-A - (3/77)Leighton 5 Associates LOG OF TRENCH N:n-u> «•*' IO Dcnsi ty (pcf) Moisture Sample No. U.S.C.S. 00 LJ UJ §-F 5 rrrr CO•l-l +Jrt UJ ,C rrNtr § (H 0) Ot) D.EquipmentGEOLOGICUNITDESCRIPTIONDATEGEOLOGICATTITUDESt- X) -T 88 5 -5 CD ti t I I I I lilt t t i 501-A - (3/77)Leighton 5 Associates LOG OF TRENCH to UJ(—c a:UJCu §c. it—Iei UJ UJ Density |S Compaction Moisture Sample No. U.S.C.S. 0- £ § cj u x-ca -oVM00o o rt v UJ O £> M Q a (H0. G.Equipmenu O =3UJw .DESCRIPTIONb-(,-SfDATEGEOLOGCATTITUDESSQrvt-1 ft 1 -uru S-root-izts-nal rocr_crd.Vfe ooccasbrown, damp,ts o£6ly inte H-(f• - o o c G \Tl <U <Ts I §•«? UJ UJ 'III lilt 1 In H—H \0 i--i I I I I 01-A - (3/77) -1 Leighton 5 Associates APPENDIX C 4850373-02 . APPENDIX C SEISMIC REFRACTION SURVEY Field Method and Equipment A seismic refraction survey was performed at the Calavera Hills site in San Diego, California on June 6, 1985 by David C. Seymour. Three seismic refraction lines were run; lines I and 2 were each 165 feet long and Line 3 was I 10 feet long. Geophones were spaced 15 feet apart for Lines I and 2, and 10 feet apart for Line 3. The approximate locations of the seismic refraction lines are indicated on the Geotechnical Map (Plate I) A 16-pound sledgehammer was used as an energy source to produce the seismic waves. The seismic waves were recorded on our 12-channel Geo-Metrics Model I2IOF signal enhancement refraction/reflection seismograph. A paper record of the field data was obtained from the instrument's oscillograph. Relative elevations were measured at each geophone along the line for making elevation correc- tions. For this investigation, we placed the energy source at the ends and center of the survey lines. The length of the lines, geophone spacing, and placement of the energy sources along the line allowed for optimum data collection. Data Reduction and Interpretation The seismic data can be used to determine layers of soil and rock, as well as the depths to different layers. The refraction method assumes that each successively deeper layer has a higher velocity than the layer immediately overlying. This assumption is satisfied in most field applications. In those cases where a lower velocity layer underlies a higher velocity layer, the lower layer cannot be recorded because the seismic wave is totally refracted. The maximum thickness of the low-velocity layer can be estimated (Cum- mings, I960). The data on the paper record were used to plot the arrival time of the seismic wave at each geophone station in the form of a time-distance graph. These curves were corrected for the elevation differences along the line in order to eliminate irregularities in the data not associated with the actual soil and rock layers. The corrected data were replotted on a time-distance graph and used for interpretation. Changes in the slopes of the velocity curves indicate changes in the physical properties of the earth materials. Such changes commonly are geologically interpreted as differences in soil or rock layers. Abrupt .offsets in the velocity curves may indicate near-vertical contacts between rock types or faults. For this project, the corrected velocity curves were used to interpret the changes in physical properties and to infer soil and rock types associated with those changes. In addition, calculations were made to determine the depths to the different layers (Dobrin, 1976; Tel ford, 1976). C-i RPABIL URVE fir 4< 5S-R 115 Qi» J31/8 Ilri QfL ± Rippers D7G Ripper Performance • Estimated by Seismic Wave Velocities Velocity In Meters Per Second x Velocity In Feet Per Second x 1000 0 2 3III 1 2 3 4-5 6 7 8 9 10 11 12 13 14 15 TOPSOIL CLAY GLACIAL TILL IGNEOUS ROCKS GRANITE BASALT TRAP ROCK SEDIMENTARY ROCKS SHALE SANDSTONE SILTSTONE CLAYSTONE CONGLOMERATE BRECCIA CALICHE LIMESTONE METAMORPHIC ROCKS SCHIST SLATE MINERALS & ORES COAL IRON ORE ^<q^^W^^^ T ^:!:!:!:!:ifo^'•'F:-x*:^k\\^\\x^^ ~ 'i;..T:.ifcS>^^^^^^^ ~ .^sS^\S>^N, > OIPDiBlp VA«r.lMAI fvTv.'iV.-vivJ NON-RIPPABLE C\V>\\\\V3 56 i I D8K Ripper Performance • Multl or Single Shank No. 8 Series D Ripper • Estimated by Seismic Wave Velocities Rippers Velocll) Veloc 0 t In Meters Per Second x 1000 1 i 1 23 4 I 1 I I 1 1 Ity In Feel Per Second x 1000 0 1 2 3 4 5 6 -7~~ 8 9 10 11 12 13 14 IS TOPSOIL • CLAY GLACIAL TILL IGNEOUS ROCKS GRANITE BASALT TRAP ROCK SEDIMENTARY ROCKS SHALE SANDSTONE SILTSTONE CLAYSTONE CONGLOMERATE BRECCIA CALICHE LIMESTONE METAMORPHIC ROCKS SCHIST SLATE MINERALS & ORES COAL IRON ORE KTp'Snvi ." 7 •' M?l* Ssm- 2211 ^trr "•T7 jrvrjv •:•:•:•:•: '"?' ^i: yx^}^^^^^^\^^^^^^x^^^^^>^^^>^^^^^s1 t3w:*:R^^^^^^v^ Av^Vi.'jl^'^T^X^NsX^^NN^NN^NNN^ —*~ --..-^i;:•x•:•:•:•:•:•^:•^^^^^\^^Cvsv^<^N^^\^\^NN "IX-X^^^X^NS^^NNV^NN^"2•x•x;x:::x:::i^^^<^^^^\^^^^^^^N^ . |::::::::::x::::?^SNSSNS^S>NSS^N ^-rrr- S=-r- --.-.-J;x::;x;:X;;lf^S^<<>^^sSSS>NSSN; I:::::::::::::::- J,\\\\\\\V\\\\\\\\\\ •- • ••"•»«,..J.-J ,,J lil'i m^ x•x•x•^x•x^i'^^^^v^^s^>^^^>>sx^s^>s^| - , .-*,,-, ,, ^.y..x^:.:.:.^Is^\^^xv^v^xv^^^^N'^s^^^ . <, r^-iiS^xxvX': A-1 RIPPABLE ETffiSffSHffll [^<S^^N^^^S vWXX11OOOvS>v\\\\ \>OO>AA1*OO\1\A^OOOS\^v^NC1' MARRINAI t.::::;::::-fi wnM.BIPPABI F t^^--\\\^t m m * 57 Rippers D9H Ripper Performance • Multi or Single Shank No. 9 Series D Ripper • Estimated by Seismic Wave Velocities Velocll Veloc 0 1 f In Mm»r<i Per fiornnrt » 1fXVl 1 , , 1 I f 234 1 i 1 1 1 lly In Feel Per Second x 1000 0 1 2 3 456 7 B 9 10 11 12 13 14 15 TOPSOIL CLAY GLACIAL TILL IGNEOUS ROCKS GRANITE BASALT TRAP ROCK SEDIMENTARY ROCKS SHALE SANDSTONE SILTSTONE CLAYSTONE CONGLOMERATE BRECCIA CALICHE LIMESTONE METAMORPHIC ROCKS SCHIST SLATE MINERALS & ORES COAL IRON ORE rrr"1"^] ^=r ^.rr^r3 /«*•:•'•:• •*?• .ir*" ••.•*'•£• ^"^••* . _ — •• •=^;rrrr • ;.- v.— rr •XvX ^•^:•:•^;4x^^^c^^^^^^x^N^^N^^^ . i^:X::::::i\^s^s^^^X' 7^^if^^^^^^^^^S^^\^^s^^^ ^J^T^t^^^1 ^^•--. .- '..•.;.^'^^'::: ; ; ; : j^^| — ••iwri-xwl.lk^s _L' IvXvXxXv/l^vSSS^ r? •*•* ' ' * *" *™^ ^_; r~~ •-— :iVxvXxyx-yyy-:! ^SSws^1 "-'"'TTiil v!-!w!v!vXv!vi^^ 1 ;v ^<?^•^;•;vI•^x•^l^OsN\s^\vCv^^l^^^^^ . . •'^••"^.;A:.:.;.:.:.;.;.;^-1vsv^vv^^ SX<S> h — -• • - ~~r- ^.....;............:.xt^^v] • >:•:•:•:•:•:•:•:•:•:•:• KIOM-RIPPARI P KX\\X\\\VJ 58 q q « 9 ' v'ietiir Vilocl I • 1 1 flH I 1 • In Mtltti fti StconJ x 1000 If tn ftil Per Second « 1000 ( ni APIA) TII i IGNEOUS GRANITE BASALT TRAP ROCK SEDIMENTARY SHALE SANDSTONE SILTSTONE CLAYSTONE CONGLOMERATE BRECCIA CALICHE LIMESTONE METAMORPHIC SHIST SLATE MINERAL & ORES COAL IRON ORE D10 Ripper Performance • Mult! or Single Shank No. 10 Ripper • Estimated by Seismic Wave Velocities ) 1 2 3 i 1 i i . 1 i 4 I ) 1 2 3 45 6 7 8 9 10 II 12 13 t iiii1 j::;.'1*-.-":-— ^T-T-^ - f*>ii-<r-rlT3^.i'^°.('VJE'.'T1fli Y///////////////////}//////// Rippers 14 15 7WHt^^K ^rf\ *"J**-iin't*n'r''^£f "' * *7^'V " ^liSr?" *f^ **" ^r*"**' '»• ••*'''• ' jJH f/y/Y//W/// I ' ' ' 1"^Tiilfri "^ I'^lT'^'h'.'^.!'^ ^'"ij^1'1 "" iiT* •" J^^u*-"!!-*^ii?''1^^ •'''*r - J""ffb.| V///////////^ ^ ///// ///// ///////f y//^?j ^^"^^••7?^^"^". • ^->2IlJf .5H'.«5»C.. -,-• -i.-ia^ YM//////////////.'t '/.'///, ^' ' •' ' *' f^ "i'*^**i ^-»7^" *^-'t'S)*^*^'"' -^tliril'l*<rtJiI^^" *T' ' " Ctitfl Y/////////////(/////.'/f////f//1 • ; I f•M1-*'^ lp?^*^*^K^>-7'i:^1^ '*'?t^T?^pM?fl'> 'jffi^'t'* 2T3 """••' ,*-ji| " "'••—— Y7?7777777777Zr i ' ' r _,-, ,,. , ' ^. --' II 1 '•""*"{ i " "*iT f'f 'v ' * *^~ (V 'i^ir''?* i ii i i'diMti ^1 V/J/////////////// II--1, ..,,...* r n, ..'... . ,.,«T^ ..... " ' ' - ^r3T5pT7^?!y.CT!rtlpj-A!^^t£ . 1OWM5JB ^///77/Pi , v^sjir r A ^^^' i^-^TSrif^'p'W'r'^flS ^i^_?^yrVi*' ^rt^ r ^x« 'j///////////////////// "ZSHr-*iL^^-i?ar-ff»*wfr«-m4»=an 'it "" ie*dH.'l« ' /? h~ V'///// ftWff ////////>,>**,, i //s/^/// '/s///// RIPPABLE SSS3GB MARGINAL. 1 ) NON-RIPPABLE V//MM\ I APPENDIX D A850373-02 ,; APPENDIX D SAMPLING AND LABORATORY PROCEDURES SAMPLING PROCEDURES Disturbed Samples; • Bulk samples of representative surface and subsurface materials were obtained from the exploratory trenches. The depth at which these samples were obtained is shown on the trench logs (Appendix B). These samples were bagged and transported to our laboratory for testing. LABORATORY TESTING PROCEDURES Classification Tests; Typical, materials were subjected to mechanical grain-size analysis by wet sieving with U.S. Standard brass screens (ASTM D422). Hydrometer analyses were performed where appreciable quantities of fines were encountered. The data was evaluated in determining the classification of materials. A graphical presentation of the grain-size distribution is presented in the test data and the Unified Soil Classification is presented in the test data and the trench logs. Maximum Density Tests; The maximum dry density and optimum moisture content of typical materials were determined in accordance with ASTM D1557-78. The results of these tests are presented in the test data. Expansion Index Tests; The expansion potential of selected materials was evaluated by the Expansion Index Test (U.B.C. Standard No. 29-2). Specimens were remolded at near-optimum moisture content to 90 percent relative compaction under a given compactive energy to approximately 50 percent saturation. The prepared specimens (4" diameter x I" length) were loaded to an equivalent I4^psf surcharge and were inundated with tap water until volumetric equilibrium was reached. The results of these tests are presented in the test data. Atterberg Limits; The Atterberg Limits were determined in accordance with ASTM D423 and ASTM D424 to assist in the engineering classification of fine-grained materials GENERAL NOTE; All references to the American Society for Testing and Materials (ASTM) imply the latest standards. D-i GRAVEL Coarea 1 Fine SAND Coand Medium 1 Fine FINES (Silt or Clay) U.S. STANDARD SIEVE NUMBERS 3" 1 1/2"3/4" 3/8" 4 10 HYDROMETER a • X 8Oo m SO cc 111 BOz iZ 40 I- 5 30u01 ao Li. - H •-— -•-.1 »J S \ ^ \ (i \ \'"* 60 10 1 0.6 0.1 O.O6 GRAIN SIZE IN MILLIMETERS 0.01 O.OOB O.O01 O.OOOB El SYMBOL • BORING NUMBER T-l SAMPLE NUMBER 1-1 DEPTH <FEET> 0-3 LIQUID LIMIT PLASTIC LIMIT PLASTICITY INDEX SOIL TYPE SM U.S. STANDARD SIEVE NUMBERS 3" 1 1/2" 3/4" 3/8" 4 10 2O 40 SO 100 20O HYDROMETER 100 H 5 TO ec lit ga. 1 LU 3Ooac a. 10 0 -^t —• ] >X. ik. V,k \ik li ~1 BO 10 1 0.6 O.f O.OB GRAIN SIZE IN MILLIMETERS 0.01 O.OOO O.OO1 O.OOOB SYMBOL • BORING NUMBER T-4 SAMPLE NUMBER 4-1 DEPTH (FEET) 1-2 LIQUID LIMIT PLASTIC LIMIT PLASTICITY INDEX SOIL TYPE SM LEKX1OM sno ASSOCIATES Project No. 4850373-02 CALAVERA HILLS PARK GRAIN SIZE DISTRIBUTION CURVES 3' H O UJ T05 oc UJ (K> UL 40 H g^ 3O 0 QC _— 0. 10 GRAVEL Coarse Fine SAND CoaneJ Mediun Fine FINES (SJIt or Clay) U.S. STANDARD SIEVE NUMBERS HYDROMETER 1 1/2"3/4'^3/8" 4 1O 2O 40 BO 10O 2OO - 1 j i i i L ^ ^ ... .... "**"•> ^X s,\ \\' BO 1O 1 O.S 0.1 O.OS GRAIN SIZE IN MILLIMETERS 0.01 O.OO6 O.OO1 O.OOO5 SYMBOL • BORING NUMBER T-8 SAMPLE NUMBER 8-1 DEPTH (FEET) 0-0.5 LIQUID LIMIT PLASTIC LIMIT PLASTICITY INDEX SOIL TYPE SC U.S. STANDARD SIEVE NUMBERS HYDROMETER H x moO n > 70$ *° m- AO C Ul soz "° "• 401- **Zni 3n. O GC |M JO Q. 10 BO 10 1 O.B 0.1 O.OB 'GRAIN SIZE IN MILLIMETERS 0.01 O.OOB 0.001 O.OOOB SYMBOL BORING NUMBER SAMPLE NUMBER DEPTH (FEET) LIQUID LIMIT PLASTIC LIMIT PLASTICITY INDEX SOIL TYPE LEKXTON ind ASSOCIATES Project No. 4850373-02 CALAVERA HILLS PARK GRAIN SIZE DISTRIBUTION CURVES MAXIMUM DENSITY TEST RESULTS SAMPLE 1 2 3 SOIL DESCRIPTION Greenish tan to light green 9 silty fine to medium sand Medium brown to gray-brown, silty fine sand Light greenish gray, slightly silty_, clayey sand MAXIMUM DRY DENSITY (PCF) 115.0 120.5 116.5 OPTIMUM MOISTURE CONTENT (%) 14.0. 12.0 13.0 * UOHTOM and ASSOCIATES I&L.Project No. 4850373-02 CALAVERA HILLS PARK I i I I I TEST NO. 1 2 SAMPLE LOCATION T-4 T-8 INITIAL MOISTURE (%) 2.8 5.0 COMPACTED DRY DENSITY (PCF) 109.0 105.1 FINAL MOISTURE (%) 18.5 20.6 VOLUMETRIC SWELL (%) 0.042 0.048 EXPANSION INDEX 42 48 EXPANSION POTENTIAL Low Low LfclGHTON i"0 ASSOCIATES Project No. 4850373-02 CALAVERA HILLS PARK EXPANSION INDEX TEST RESULTS tuas 1 a i a l l l i1 1 I l l i l l l 1 1 l ATTERBERG SYMBOL 60 M - 30 u *o 0 CL-ML LOCATION T-8 XXxV • ^ / ML 1 / . 9 IO 20 • LIU ( CL X/ DEPTH 0'-0.5' X ML a OL X _. LIMITS TEST RESULTS FIELD MOISTURE (%) * CH x / MH.,a XX OH LL (%) 36.9 PL (%) 22. ,0 PI (%) 14.9 u.s.c.s. CL 30 40 90 SO TO 80 Liquid Limit),0/. tilGKIC>J and ASSOCIATES Project No. 4850373-0*? CALAVERA HILLS PARK r. 3 I I II.1'" 'i • I I I ::-u I I I I I GENERAL EARTHWORK AND GRADING SPECIFICATIONS 1.0 General Intent These specifications present general procedures and requirements for grading and earthwork as shown on the approved grading plans, including preparation of areas to be filled, placement of fill, installation of subdrains, and excavations. The recommendations contained in the geotechnical report are a part of the earthwork and grading specifications and shall supersede the provisions contained hereinafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations-which could supersede these specifications or the recommendations of the geotechnical report. 2.0 Earthwork Observation and Testing Prior to the commencement of grading, a qualified geotechnical consultant (soils engineer and engineering geologist, and their representatives) shall be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report and these specifications. It will be necessary that the consultant provide adequate testing and observation so that he may determine that the work was accomplished as specified. It shall be the responsibility of the contractor to assist the consultant and keep him apprised of work schedules and changes so that he may schedule his personnel accordingly. It shall be the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the work in accordance with applicable grading codes or agency ordinances, these specifications and the approved grading plans. If, in the opinion of the consultant, unsatisfactory conditions, such as questionable soil, poor moisture condition, inadequate compaction, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the consultant will be empowered to reject the work and recommend that construction be stopped until the conditions are rectified. Maximum dry density tests used to determine the degree of compaction will be performed in accordance with the American Society for Testing and Materials test method ASTM D1557-78. 3.0 Preparation of Areas to be Filled 3.1 Clearing and Grubbing; All brush, vegetation and debris shall be removed or piled and otherwise disposed of. 3.2 Processing; The existing ground which is determined to be satisfactory for support of fill shall be scarified to a minimum depth of 6 inches. Existing ground which is not satisfactory shall be overexcavated as specified in the following section. Scarification shall continue until the soils are broken down and free of large clay lumps or clods and until the working surface is reasonably uniform and free of uneven features which would inhibit uniform compaction. a 3.3 OverexcQvotion; Soft, dry, spongy, highly fractured or otherwise unsuitable ground, extending to such a depth that surface processing cannot adequately improve the condition, shall be overexcavated down to firm ground, approved by the consultant. 3.4 Moisture Conditioning; Overexcavated and processed soils shall be watered, dried-back, blended, and/or mixed, as required to attain a uniform moisture content near optimum. • —~: 3.5 Recompoction; Overexcavated and processed soils which have been properly mixed and moisture-conditioned shall be recompacted to a minimum relative compaction of 90 percent. . •-. 3.6 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. The lowest bench shall be a minimum of 15 feet wide, shall be at least 2 feet deep, shall expose firm material, and shall be approved by-the consultant. Other benches shall be excavated in firm material for a minimum width of 4 feet. Ground sloping flatter than 5:1 shall be benched or otherwise overexcavated when considered necessary by the consultant. 3.7 Approval; All areas to receive fill, including processed areas, removal areas and toe-of-fill benches shall be approved by the consultant prior to fill placement. 4.0 Fill Material " ~" " ~ • 4.1 General; Material to be placed as fill shall be free of organic matter and other deleterious substances, and shall be approved by the consultant. Soils of poor gradation, expansion, or strength characteristics shall be placed in areas designated by the consultant or shall be mixed with other soils to serve as satisfactory fill material. 4.2 Oversize; Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 12 inches, shall not be buried or placed in fills, unless the location, materials, and disposal methods are specifically approved by the consultant. Oversize disposal operations shall be such that nesting of oversize material does not occur, and such that the oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 feet vertically of finish grade or within the range of future utilities or underground construction, unless specifically approved by the consultant. 4.3 Import; If importing of fill material is required for grading, the import material shall meet the requirements of Section 4.1. 5.0 Fill Placement and Compaction 5.1 Fill Lifts; Approved fill material shall be placed in areas prepared to receive fill in near-horizontal layers not exceeding 6 inches in compacted thickness. The consultant may approve thicker lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer shall be spread evenly and shall be thoroughly mixed during spreading to attain uniformity of material and moisture in each layer. 5.2 Fill Moisture; Fill layers at a moisture content less than optimum shall be watered and mixed, and wet fill layers shall be aerated by scarification or shall be blended with drier material. Moisture-condition ing and mixing of fill layers shall continue until the fill material is at a uniform moisture content at or near optimum. 5.3 Compaction of Fill; After each layer has been evenly spread, moisture- conditioned, and mixed, it shall be uniformly compacted to not less than 90 percent of maximum dry density. Compaction equipment shall be adequately sized and shall be either specifically designed for soil compaction or of proven reliability, to efficiently achieve the specified degree of compaction. . . 5A Fill Slopes; Compacting of slopes shall be accomplished, in addition to normal compacting procedures, by backrolling of slopes with sheepsfoot rollers at frequent increments of 2 to 3 feet in fill elevation gain, or by other methods producing satisfactory results. At the completion of grading, the relative compaction of the slope out to the slope face shall be at least 90 percent. 5.5 Compaction Testing; Field tests to check the fill moisture and degree of compaction will be performed by the consultant. The location and frequency of tests shall be at the consultant's discretion. In general, the tests will be taken at an interval not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of embankment. 6.0 Subdrain Installation ' • ' Subdrain systems, if required, shall be installed in approved ground to conform to the approximate alignment and details shown on the plans or herein. The subdrain location or materials shallnot be changed or modified without the approval of the consultant. The consultant, however, may recommend and upon approval, direct changes in subdrain line, grade or material. All subdrains should be surveyed for line and grade after installation and sufficient time shall be allowed for the surveys, prior to commencement of filling over the subdrains. *7.0 Excavation Excavations and cut slopes will be examined during grading. If directed by the consultant, further excavation, or overexcavation and refilling of cut areas shall be performed, and/or remedial grading of cut slopes shall be performed. Where fill- over-cut slopes are to be graded, unless otherwise approved, the cut portion of the slope shall be made and approved by the consultant prior to placement of materials -.. for construction of the fill portion of the slope. I I I I TRANSITION LOT DETAILS CUT-FILL LOT NATURAL GROUND I -51 MIN. . COMPACTED -3f ILLr_^_^r_-±-_- ^ 30" MIN. OVEREXCAVATE AND RECOMPACT UNWEATHERED BEDROCK OR MATERIAL APPROVED BY THE GEOTECHNICAL CONSULTANT CUT LOT NATURAL GROUND REMOVE. UNSUITABLE MATERIAL 5'MIN. • COMPACTED------j^^L-.- 30" MIN. OVEREXCAVATE AND RECOMPACT UNWEATHERED BEDROCK OR MATERIAL APPROVED BY THE GEOTECHNICAL CONSULTANT NOTE: Deeper overexcavation and recompaction shall be performed if determined to be necessary by the geotechnical consultant. SIDE HILL CUT PAD DETAIL NATURAL. GROUND >-' OVEREXCAVATE AND RECOMPACT (REPLACEMENT OVERBURDEN — OR UNSUITABLE MATERIAL FINISHED CUT PAD BENCHING Pad over excavation and recompaction shall be performed if determined to be necessary by the geotechnical consultant. UNWEATHERED BEDROCK OR MATERIAL APPROVED BY — THE GEOTECHNICAL CONSULTANT SUBDRAIN AND KEY WIDTH REQUIREMENTS DETERMINED BASED ON EXPOSED SUBSURFACE CONDITIONS AND THICKNESS OF OVERBURDEN BENCHING DETAILS FILL SLOPE PROJECTED PLANE I to I maximum from toe of slope to approved g NATURAL GRODNO REMOVE Typical' UNSUITABLE MATERIAL BENCH HEIGHT IS'MIN. I KEY p-OWEST BENCH "1DEPTH(KEY) FILL-OVER-CUT SLOPE REMOVE. UNSUITABLE MATERIAL Typical II^BENCH-H \ BENCH HEIGHT . -mr jg 19* MIN. J I LOWEST BENCH | CUT FACE To be constructed prior to fill placement CUT-OVER-FILL SLOPE CUT FACE To Bt Constructed Prior to Fill Placement NATURAL .GROUND OVERBUILD t TRIM BACK PROJECT PLANE I to I maximum toe of slope to approved ground TYPICAL BENCH HEIGHT 2< HIM. KEY DEPTH ' IS' MIN. I r~~LOWEST BENCH"""! NOTES; • LOWEST BENCH: Depth and width subject to field change based on consultant's inspection. SUBDRAINAGE:. Back drains may be required at the discretion of the geotechnical consultant. FINISHED GRADE ALTERNATE A 15 MIN COMPETENT MATERIAL OR BEDROCK (AS DETERMINED BY THE ENGINEERING GEOLOGIST OR SOILS ENGINEER) ALTERNATE B 15 MIN. //-=" == COMPETENT MATERIAL OR BEDROCK (AS DETERMINED BY THE ENGINEERING GEOLOGIST OR SOILS ENGINEER) NOTES 1. ALL FILL MUST BE APPROVED BY THE SOILS ENGINEER AND SHOULD BE COMPACTED TO AT LEAST 90SRELATIVE COMPACTION (ASTM D 1557-70). 2. ZONE A SHOULD CONSIST OF COMPACTED SOIL FILL ONLY (NO ROCK FRAGMENTS OVER 6 INCHES INMAXIMUM DIMENSION). 3. ZONE A SHOULD HAVE A MINIMUM THICKNESS OF 15 FEET (AS SHOWN), BUT MUST EXTEND 3 FEETBELOW THE DEEPEST UTILITY. *. EXCESSIVE OVERSIZE ROCK CAN BE WINDROWED IN AREAS AS SHOWN IN ALTERNATES A OR B. SELECTION OF ALTERNATES A OR B CAN BE MADE BY THE EARTHWORK CONTRACTOR. DEPENDING ON THE SITE GEOMETRY. 5. MAXIMUM SIZE AND SPACING OF WINDROWS SHOULD BE IN ACCORDANCE WITH THE ABOVE FIGURES (ALTER-NATES A AND B). 6. WINDROWS SHOULD BE PLACED IN EXCAVATED TRENCHES. APPROVED GRANULAR SOIL (SE-30) SHOULD BEFLOODED IN THE WINDROW TO FILL VOIDS AROUND AND BENEATH ROCKS. NO ROCK FRAGMENTS OVER 3FEET IN MAXIMUM DIMENSION SHOULD BE USED IN WINDROWS. 7. ROCK PLACEMENT. FLOODING OF APPROVED GRANULAR FILL. AND FILL PLACEMENT SHOULD BE CONTINUOUSLYINSPECTED BY THE GEOTECHNICAL ENGINEER. UiGHTON ana ASSOCIATES Project No. OVERSIZE ROCK DISPOSAL DETAIL ROCK DISPOSAL DETAIL FINISH GRADE SLOPE FACE COMPACTED FILL.O'_MIN jt MIN OVERSIZED-- WINDROW GRANULAR SOIL To fill voids, densified by flooding PROFILE ALONG WINDROW SPECIFICATIONS FOR CLASS 2 PERMEABLE MATERIAL (CALTRANS SPECIFICATIONS) Sieve Size % Passing 1" 3/4" 3/8" No. 4 No. 8 No. 30 No. 50 No. 200 100 90-100 40-100 25-40 18-33 5-15 0-7 0-3 Backfill, Compacted to 90 percent relative density* Retaining WaTU. Finished Grade Floor Slab 1 I"WJ$y/<$'//&'// A 1' minimum 7 :Wall Footing' ^ &)>..-. <> - •• • jf/^2/ ^SJ^7^^>^S^^57^~^ 1 1 f k\V5^?S^J^ \ 0 « 00 « o o V 0 * o 0 0° 0 0 v '• minimum0 * « o * O 0 •• 0 •0 0 a °> .' ' '•o o o o /^N o»CI^,f o~\r \ lass 2 Permeable Filter /aterial , Compacted to 90 percent relative density* 6" Diameter perforated PVC pipe (schedule 40 - or equivalent). Minimum 1 percent gradient tosuitahlp nntlpf: Minimum 6" layer of filter rock beneath •pipe *Based on ASTM D1557- 82 ::: I I I I I f I CANYON SUBDRAIN DETAIL BENCHING NATURAL GROUND - COMPACTED FILL -------^:- REMOVE UNSUITABLE MATERIAL SUBDRAIN TRENCH SEE ALTERNATES A&B SUBDRAIN Perforated Pipe Surrounded WithALTERNATE A: Filter Material FILTER MATERIAL- FILTER MATERIAL Filter material shall be Class 2 permeable materialper State of Calitornia Standard Specifications. • or approved alternate. Class 2 grading as follows: •PERFORATED PIPE' 6" 0 MIN. SIEVE SIZE 1' 3/4' 3/8' No. 4 No. 8 No. 30 No. 50 No. 200 PERCENT PASSING 100 90-100 40-100 25-40 18-33 5-15 0-7 0-3 SUBORAIN 1 1/2" Gravel WrappedALTERNATE B: In Filter Fabric 6" MIN. OVERLAP FILTER FABRIC (MIRAFI 140 OR APPROVED EQUIVALENT DETAIL OF CANYON SUBDRAIN TERMINAL DESIGN riNISHEO GRADE- FILTER FAtjniC NATIVF IACKFILL (MIRAFI l*0 OHNATIVE BACKFILL APPROVED EC3UIVALENT) /2HMAX.QRAVEL OR-^AHernale B-2 APPROVED EQUIVALENT fft. 3/f». — NONPERFORATED 6"« HIM. •— IfcMAX.OPEN CRADCO CaAVEL OR APPROVED EQUIVALENT • SUBDRAIN INSTALLATION - Subdroin pipe shall be installed with perforations down or, at locations designated by the geotechnical consultant, shall be nonperforated pipe. e SUBDRAIN TYPE - Subdrain type shall be ASTM C508 Asbestos Cement Pipe (ACP) - or ASTM D275I, SDR 23.5 or ASTM DI527, Schedule 40 Acrylonitrile Butadiene Styrene (ABS) or ASTM D3034 SDR 23.5 or ASTM DI785, Schedule 40 Polyvinyl Chloride Plastic (PVC) pipe or approved equivalent. SLOPE BUTTRESS OR REPLACEMENT FILL DETAIL OUTLET PIPES 4" ONonperforated Pipe, 100' Max. O.C. Horizontally, 30' Max. O.C. Vertically FILL BLANKET 30" MIN. BACK CUT :l OR FLATTER BENCHING SUBDRAIN SEE ALTERNATES A & B 2% Min.------------.yLi ALTERNATE A KEY WIDTH FILTER MATERIALEQUIPMENT SIZE - GENERALLY IS FEET DETAIL A-A* 3TES; Fill blanket, back cut, key width and key depth are subject to field change, per report/plans. Key heel subdrain, blanket drain, or vertical drain may be required at the s discretion of.the geotechnical consultant. SUBDRAIN INSTALLATION - Subdrain 'pipe shall be installed with perforations down or, at locations designated by jthe geotechnical consultant, shall be nonperforated pipe. 'SUBDRAIN-TYPE - Subdrain type shall be ASTM C508 Asbestos Cement Pipe ((ACP) or ASTM D275I, SDR 23.5 or ASTM DI527, Schedule 40 Acrylonitrile Butadiene Styrene (ABS) or ASTM D3034 SDR 23.5 or ASTM DI785, Schedule 40 Polyvinyl Chloride Plastic (PVC) pipe or approved equivalent. 10' HIM. EACH SICE I CCAPF ALT. 0 Filter material shall be Class 2 permeable material per State of Calitornia Standard Specifications, or approved alternate. Class 2 grading as follows: SIEVE SIZE 1' 3/4' 3/8* No. 4 No. 8 NO. 30 No. 50 No. 200 PERCENT PASSING 100 90-100 40-100 25-40 18-33 5-15 0-7 0-3 POSITIVE SEAL SHOULD BE PROVIDED AT THE JOINT GRAVEL OR V( APPROVED J EQUIVALENT * 3 It. 3/11. T-CONNCCTONOUTLET ^..FIPE-.C-- ALTERNATE B • FILTER FABRIC (MIRAFI 140 OR APPROVED EQUIVALENT) DETAIL OF BUTTRESS SUBDRAIN TERMINAL DESIGN FINISHED GRADE-- FILTER FABRIC (MIRAFI HO OR APPROVED EQUIVALENT) J-IO'l NATIVE SACKFUL -""I |-« 15' HIM. • -» HONP£BFORAHD 4-0 H /"" 5'HIN. IN. — "• JO1 niN.— \ PERFORATED ' 4-e KIN. PIPE »(::!'•-• llTwAX.OPEN GRADED GRAVEL OR APPROVED EQUIVALENT