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HomeMy WebLinkAboutCT 81-10; Carlsbad Research Center Lots 44-45; Soils Report; 1989-07-26SAN DIEGO GEOTECHNICAL CONSULTANTS, INC. SOlL ENGINEERING 8 ENGINEERING GEOLOGY July 26, 1989 Puritan-Bennett c/0 Ehrlich-Rominger 4800 El Camino Real Los Altos, California 94022 Attention: John Brown SUBJECT: ADDENDUM LETTER - _. -- - Job No.,05-7928-001-00-00 Log No. 9-1908 Carlsbaa ReSSarCn center, Lots 44 and 45 Carlsbad, California References: San Diego Geotechnical Consultants, Inc., June 6, 1989, "Foundation Investigation, Lots 44 and 45 CarlsbadResearch Center, Carlsbad, California", Job NO. 05-7928-001-00-00 Gentlemen: The purpose of this letter is to address some items of concern raised during our meeting on July 25, 1989. The first item was the placement of a "mole strip" around the building perimeter. It was originally suggested that the mole strip consist of a 3 foot wide section of relatively level gravel. I would strongly recommend against placing anything of this nature against the exterior of the building. The reason for this is that such a gravel filled strip will tend to act as a sump to collect irrigation and rain water, thereby allowing it to percolate into the foundation soils. As you well know the soils on this site are very highly expansive, any water introduced into the soil could result in various degrees of cracking and movement depending on the site preparations used. If such a mole strip is considered necessary, I would recommend that a concrete slab sloping away from the building at a minimum slope of 2 percent be used. The soils within 5 feet of this slab should continue to slope away at the slopes recommended in section 7.4 of our report. Due to the highly A SUBSIDIARY OF THE IRVINE CONSULTING GROUP, INC 9240 TRADE PLACE, SUITE 100 - SAN DIEGO. CA 92126. (61~91536-1102 . FAX: (619i 536-1306 Puritan-Bennett Job NO. 05-7928-001-00-00 '/, Ehrlich-Rominger Log No. 9-1908 I Page 2 expansive nature of the soils the recommendations in section 7.4 should be strictly adhered to, to mitigate expansive soil damage. Recent analyses in the CRC area have indicated that a 3 percent lime mixture may be able to reduce the expansion potential to a reasonable level. This value may provide a cost savings over the 4 percent mixture previously used. Further testing will be necessary to accurately pin down the recommended amount of lime. Joseph Sutton with Dasse Design has indicated to me that the actual foundation loads will be on the order of twice those presented in our report. Based on the site conditions and the soil types present it is our opinion that these loads should not require any additional recommendations or changes to our original recommendations. Upon review of the site plan and after discussions during the meeting it was suggested that an additional pavement section based on a Traffic Index of 6.5 be calculated to accommodate large tractor trailer trucks. Our calculations, based on an R value of 23 indicate that a pavement section consisting of 4 inches of Asphalt concrete over 10 inches of Class II aggregate base course could be used for preliminary design. We recommend that the R value be confirmed once roadways and parking areas are cut to the proper grade. Puritan-Bennett '/, Ehrlich-Rominqer Job No. 05-7928-001-00-00 Log No. 9-1908 , Page 3 This opportunity to be of service has been appreciated. Should any questions arise or if we can be of further service please contact our office. Very truly yours, SAN DIEGO GEOTECBNICAL CONSULTANTS, INC. Erik J‘: Nelson, P.E. C 44102 Expiration Date: 6-30-93 Project Engineer EJN/cf - - - - - - - - - - - FOUNDATION INVESTIGATION LOTS 44 AND 45 CARLSBAD RRSEARCB CENTER CARLSBAD, CALIFORNIA PREPARED FOR PURITAN-BENNETT c/o EHRLICH-BENNETT 4800 EL CAMINO REAL LOS ALTOS, CALIFORNIA 94022 PREPARED BY SAN DIEGO GEOTECHNICAL CONSULTANTS, INC. 9240 TRADE PLACE, SUITE 100 SAN DIEGO, CALIFORNIA 92126 JUNE 6, 1989 JOB NO. 05-7928-001-00-00 LOG NO. 9-1714 ,- June 6, 1989 -. Puritan-Bennett '/, Ehrlich-Rominger 4800 El Camino Real Los Altos, California 94022 Attention: John Brown Job No. 05-7928-001-00-00 Log No. 9-1714 - SUBJECT: FOUNDATION INVESTIGATION Lots 44 and 45, Carlsbad Research Center Carlsbad, California Gentlemen: As requested, we have completed our foundation investigation for the site of the proposed commercial development. Our findings and recommendations are presented herein. In our opinion, the primary site conditions which are likely to impact the proposed development include highly expansive soil over most of the lots and a transition from bedrock to deep fill across two of the proposed building areas. Recommendations regarding these and other site conditions are provided in the attached report. If you have any questions after reviewing.our report, please do not hesitate to contact the undersigned at your convenience. This opportunity to be of professional service is sincerely appreciated. Very truly yours, SAN DIEGO GEOTECHNICAL CONSULTANTS, INC. - 4 Anthon F. Belfast Chief Engineer AFB/cf A SUBSlDlARY OF THE lR”,NE CONSULTING GROUP, INC. 9240 TRADE PLACE, SUITE 100. SAN DIEGO, CA 92126. (619) 536-l 102 . FAX: (619) 536-1306 - - TABLE OF CONTENTS - - - - - - 6.2.4 Other Hazards .......... . . . . . 9 .- - - - 1.0 INTRODUCTION ................. 1.1 Authorization .............. 1.2 Scope of Services ............ . . . . . . . . . . . . . . . 1 1 1 2.0 PROPOSED DEVELOPMENT. ............ . . . . . 2 3.0 SITE DESCRIPTION ............... . . . . . 3 4.0 SITE INVBSTIGATION .............. . . . , . 4 4.1 General ................. . . . . . 4 4.2 Field Exploration ............ . . . . . 4 4.3 Laboratory Testing Program ....... . . . . . 5 5.0 SUBSURFACE CONDITIONS ............ . . . . . 5 5.1 General ................. . . . . . 5 5.2 Point Loma Formation .......... . . . . . 6 5.3 Fill .................. . . . . . 6 5.4 Groundwater ............... . . . . . 7 6.0 SEISMICITY .................. 6.1 General ................. 6.2 Earthquake Effects ........... 6.2.1 Surface Fault Rupture ...... 6.2.2 Ground Accelerations ...... 6.2.3 Seismically Induced Settlement and Liquefaction .......... . . . . . 8 , . . . . 8 . . . . . 8 . . . . . 8 . . . . . 9 . . . . . 9 7.0 GEOTRCHNICAL EVALUATION AND RECOMMENDATIONS . . . . . . 10 7.1 General Discussion ........... . . . . . 10 7.2 Grading and Earthwork ......... . . . . . 11 7.2.1 Geotechnical Observation .... . . . . . 11 7.2.2 Site Preparation ........ . . . . . 12 7.2.3 Fill Compaction ......... . . . . . 14 7.2.4 Trench Backfill ......... . . . . . 15 7.3 Slope Stability ............. . . . . . 15 7.4 Site Drainage .............. . . . . . 16 7.5 Foundation Recommendations ....... . . . . . 17 7.5.1 General ............. . . . . . 17 7.5.2 Foundations on Non-expansive Cap . . . . . . 18 i - - - . . - - - - - - - - - TABLE OF CONTENTS (continued) 7.5.3 Post-Tensioned Slabs ............ 18 7.5.4 Moisture Conditioned Building Pad ..... 19 7.5.5 Deepened Footings (Phases II & III). .... 19 7.5.6 Settlement ................ 20 7.5.7 Lateral Load Resistance .......... 21 7.5.8 On-Grade Slabs .............. 21 7.5.9 Foundation Observation .......... 24 7.6 Earth Retaining Structures ............ 24 7.7 Reactive Soils .................. 25 7.8 Pavements ..................... 25 7.9 Review of Plans .................. 26 8.0 LIMITATIONS OF IN'A3STIGATION .............. 27 Fiqures 1 Location Map 2 Regional Fault Map Aouendices A B C D Plate 1 ATTACNMENTS References Field Exploration, Key to Borings, Figure B-l Boring Logs, Figures B-2 and B-7 Laboratory Testing Program Figures C-l through C-6 Standard Guidelines for Grading Projects Site Plan ii - .~. - - - - - - - - - .- - FOUNDATION INVESTIGATION LOTS 44 AND 45, CARLSBAD RESEARCH CENTER CARLSBAD, CALIFORNIA 1.0 INTRODUCTION This report presents the results of our Foundation Investiga- tion performed for the proposed commercial development of lots 44 and 45 at the Carlsbad Research Center in Car&bad California. The purpose of this investigation was to explore and evaluate the subsurface conditions at the site, and to provide recommendations for site preparation, and the geotechnical aspects of project design. The location of the site is shown on the Location Map provided on Figure 1. 1.1 1.2 Authorisation This investigation was conducted in accordance with the authorization of Mr. John Brown of Puritan-Bennett. The scope of services performed was consistent with our proposal number SDP9-5195, dated March 20, 1989. Stove of Services Our scope of services for this investigation included the following: 1.2.1 Review of existing geotechnical reports and literature pertinent to the project area (Appendix A): 1.2.2 Subsurface exploration utilising a truck-mounted drill rig. Samples of typical soil and rock materials were collected during drilling opera- tions; - - - - - - - - - - - - - - - - .- ADAPTED PROM U.S.Q.S. 7.5’ SAN ~~1s REY (1076) QUADRANQLE LOCATION MAP IDATE: -. - - - - - - - - - - - - Puritan-Bennett '/, Ehrlich-Rominger June 6, 1989 Job No. 05-7928-001-00-00 Log No. 9-1714 Page 2 1.2.3 1.2.4 1.2.5 1.2.6 Laboratory testing of selected samples to evaluate the pertinent engineering characteristics of the prevailing soils; Evaluation of ground shaking potential resulting from significant seismic events occurring on faults in the area: Development of site preparation and earthwork recommendations; Recommendations for an appropriate foundation system for the proposed structures, development of geotechnical criteria for foundation design, and the development of pavement section recoimuen- dations for the proposed parking areas and driving lanes. 2.0 PROPOSED DEVELOPMENT It is understood that the proposed development will consist of two-two story, concrete tilt-up structures with on-grade slabs. Based on our experience, column loads are assumed to be less than 100 kips, and wall loads less than 5 kips per linear foot. In addition to the structure, asphalt concrete paved parking areas and access drives are planned. The site has been previously rough graded during mass grading of the research park. Only a minor amount of grading is expected during the construction phase of the project. - Puritan-Bennett Job No. 05-7928-001-00-00 '/, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 3 - - - - - _- - - - - - - - It is our understanding that the project will be developed in three phases. The first phase will consist of constructing the building on lot 45 and a two-lane driveway which will loop around lot 44. Phase II will involve the construction of a similar building 1/2 the size of Phase I on lot 44. Phase III is to be the construction of the other '/* of the building for a total of two buildings. The two buildings are at this time planned to be connected by an enclosed walkway. 3.0 SITE DESCRIPTION The subject lots were previously graded during grading operations for the Carlsbad Research Center. Grading operations were observed by our personnel between July 19, 1986 and November 24, 1987. Lots 44 and 45 are located on the North side of Faraday Avenue. Lot 44 is located to the east of lot 45. Elevations on lots 44 and 45 vary from approximately 298 feet above Mean Sea Level (MSL) to 271 feet MSL. Both of the lots have been graded to approximately level pads. Sheet flow drainage on the lots is collected by small swales and directed toward storm drains located on the south west corners of the lots. No significant vegetation or landscaping improvements were noted on the site other than a grassy berm ditch has been constructed between the lots and adjacent roadways. The lot locations in relation to each other are shown on the Site Plan provided as Plate 1. - - - - - - - - - - Puritan-Bennett c/0 Ehrlich-Rominger June 6, 1989 4.0 SITE INVESTIGATION 4.1 General Job No. 05-7928-001-00-00 Log No. 9-1714 Page 4 Before starting the field work, we reviewed our previous reports and available geotechnical literature covering the project area. The resulting information, together with our field exploration, laboratory test results, and previous experience in the area forms the basis for our conclusions and recommendations in this report. The methods used for our work conform to generally accepted standards of practice for geotechnical investigations in southern California. 4.2 Field Exvloration A field investigation was performed on April 14, 1989 and consisted of a site reconnaissance and the drilling of six exploration borings. The exploration borings were placed to obtain an indication of the subsurface conditions across the site. The borings were located in the field by pacing, and using available maps. Further accuracy of boring locations is not implied. Borings were drilled using a truck-mounted, continuous flight, hollow-stem auger having a diameter of eight inches. Boring depths ranged in depth from approximately 18.5 to 33.5 feet below existing grade. Samples were obtained using a standard split spoon sampler (ASTM D1586-84), a modified California sampler with an inside diameter of 2.5 inches (ASTM D3550-84), and by collecting auger cuttings. - - - - - Puritan-Bennett Job No. 05-7928-001-00-00 '/,, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 5 Logs describing the subsurface conditions encountered are presented in Appendix B. Approximate locations of the borings are shown on Plate 1. Lines defining the change between soil or rock types on the boring logs were determined by interpolation between sample locations and are, therefore, approximations. The transition between soil types may be abrupt or may be gradual. 4.3 Laboratorv Testina Prosram Laboratory tests were performed on selected samples considered to be representative of the foundation soils. Tests were performed in accordance with the methods of the American Society for Testing and Materials (ASTM) or other accepted standards. Appendix C contains descrip- tions of the test methods and summaries of the results. 5.0 SUBSURFACE CONDITIONS 5.1 General The site is underlain by fill with depths of up to 65 feet deep, and bedrock of the Point Loma Formation. Our investigation indicates that the planned building location for lot 45 is located predominantly on cut. The north west corner of the site may extend over a shallow fill area with estimated maximum fill depth of 5 feet. The planned building location for Phases II 8 III (lot 44) are currently planned across a cut-fill transition. The center portion of the proposed location is underlain - ,- - - __ Puritan-Bennett Job No. 05-7928-001-00-00 '/,, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 6 by as much as 50 feet of fill. The two ends and the south edge of the planned building are located on bedrock cut. Fill soils were placed during mass grading for the first phase of the Carlsbad Research Center. 5.2 Point Loma Formation The bedrock materials encountered consisted mainly of highly plastic siltstone with minor amounts of fine sand. The bedrock materials encountered varied from highly to mildly weathered. The bedrock is considered generally competent in terms of bearing support for foundations. All of the bedrock materials encountered are, however, very highly expansive. Construction on these soils will, therefore require special site preparation and/or foundation design to mitigate the potential for heaving and cracking of slabs and foundations. 5.3 Fill Site preparation and placement of compacted fill on the lot is documented in the Compaction Report for Rough Grading prepared by San Diego Geotechnical Consultants, Inc. (Reference 4, Appendix A). The fill soils used were derived from cuts in the bedrock and are similar in composition. The fill consists of brown, olive-brown, red-brown, and gray, moist, stiff to very stiff, sandy silt and clayey silt. The silts are highly plastic and is classified as an MB in the Unified Soil Classifica- - Puritan-Bennett Job No. 05-7928-001-00-00 '/,, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 7 tion. The location of the transition between the cut and fill areas are approximately shown on Plate 1. Although the fill is considered suitable for foundation bearing support, based on the results of our laboratory testing, much of the soil is considered very highly expansive. Therefore, mitigating recommendations are considered necessary. In addition to expansive considerations, the fill possesses different settlement characteristics from the bedrock material. Therefore Phases II and III development should consider the potential for differential settlement, as discussed in ensuing portions of this report. 5.4 Groundwater No groundwater seepage was encountered in any of the borings at the time of our investigation. Our records indicate that a subdrain consisting of gravel wrapped in filter fabric was installed at the point of deepest fill below lot 44. A more detailed discussion of the subdrain installation can be found in Reference 4. It should be recognised that excessive irrigation on the project site or on adjacent sites can cause a perched groundwater condition to develop at some future date. This typically occurs at underlying contacts with less permeable materials, such as the interface that exists between the fill and the underlying bedrock. Because the prediction of the location of such conditions is not possible, they are typically mitigated if and when they occur. - - ..~ -. - - - - Puritan-Bennett c/0 Ehrlich-Rominger June 6, 1989 Job No. 05-7928-001-00-00 Log No. 9-1714 Page 8 6.0 SEISMICITY 6.1 General The site is considered to be a seismically active area, as can all of southern California. There are, however, no known active faults either on or adjacent to the project site. Figure 2 shows the known active faults and major earthquake epicenters in the region and their geographic relationship to the site. Because these active faults are at a substantial distance, the seismic risk at this site is considered to be low to moderate in comparison to many parts of southern California. Most seismic hazards at the site are a consequence of ground shaking caused by events on distant, active faults. The hazard level is sufficient to place the area in seismic risk zone 3 as defined in the Uniform Building Code. In addition to the information on Figure 2, Table 1 lists the active faults within 63 miles (100 kilomet- ers) of the site and the maximum probable earthquakes on those faults. By definition, the maximum probable earthquake for a given fault is the largest earthquake likely to occur within a 100 year interval. 6.2 Earthouake Effects 6.2.1 Surface Fault RUDtUre In our opinion, no credible risk of surface rupture exists at the project site. No known active faults or potentially active faults cross the site. I I I I I / I I I I I I I I I REGIONAL FAULT MAP I - .- - - - .- Puritan-Bennett c/0 Ehrlich-Rominger June 6, 1989 Job No. 05-7928-001-00-00 Log No. 9-1714 Page 9 6.2.2 Ground Accelerations In our opinion, based on information now avail- able, the most significant event likely to affect the project will be a 7.0 magnitude event on the Elsinore Fault. For the Elsinore Fault event, we estimate a peak bedrock acceleration within the project area of about 0.22g. Because the Elsinore Fault is located less than 20 miles from the site, a 30 percent reduction in acceleration is typically applied for design purposes. Design of structures should conform to the requirements of the governing agencies, as well as to the standard practices of the Structural Engineers Association of California. 6.2.3 Seismicallv Induced Settlement and Liouefaction Because of the very high relative densities of both the bedrock materials and the compacted fill which underlies the site, liquefaction or seismically induced settlements are not considered a hazard. 6.2.4 Other Hazards Because of the level topography of the site and because of the site's elevation above sea level, hazards such as seismically induced slope failures, tsunamis, or seiches are not considered hazards. -~ .- - - .- - - _- - - ,- .- _- - Puritan-Bennett Job No. 05-7928-001-00-00 c/0 Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 10 7.0 GEOTECHNICAL EVALUATION AND RECOMl4F2lDATIONS 7.1 General Discussioq No geotechnical conditions were apparent during our investigation which would preclude the site development as planned. The site condition which should most severely impact the development is the very high expansion potential of the prevailing on-site soil and the deep fill transition of Lot 44. The expansive potential of the on-site soils is at the upper end of the highest range in which the more typical recommendations in southern California can be used. Special foundation design and/or site preparation is recommended to decrease the likelihood of foundation and slab cracking due to expansive heave. We recommend that one of the following alternatives be employed to decrease the risk of movement of foundations and slabs due to expansive soils. They are given in order of increasing risk. a. Cap the building area with imported, non-expansive soil, or lime treated on-site soil, to a depth of at least four feet below the slab subgrade. b. Use a post-tensioned slab system or other structurally designed system directly on the on-site soils. The design should be based upon uplift values provided herein. Puritan-Bennett Job No. 05-7928-001-00-00 '/, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 11 C. Moisture condition the on-site soil and use a reinforced foundation and slab. It is anticipated the proposed structure on lot 44 will cross a transition from bedrock to fill, with the north central portion of the structure being underlain by up to 50 feet of compacted fill. This deep transition will require additional recommendations. Due to the fill depths associated with the transition, it is our opinion that the best foundation alternative for the fill portion of Phases II 8 III will be a deep foundation system consisting of drilled or driven piles. Such a deep foundation system should be used in conjunction with the previously mentioned mitigation measures for expansive soils. The remainder of Section 7.0 presents our recommendations in detail. These recommendations are based on empirical and analytical methods typical of the standard of practice in southern California. If these recommenda- tions appear not to cover any specific feature of the project, please contact our office for additions or revisions to our recommendations. 7.2 Gradins and Earthwork 7.2.1 Geotechnical Observation During grading, San Diego Geotechnical Consul- tants, Inc. should provide observation and testing -- .- .- - -- .- ._ .- ._ .- - .__ Puritan-Bennett Job No. 05-1928-001-00-00 c/0 Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 12 services continuously. Such observations are considered essential to identify field conditions that differ from those anticipated by the preliminary investigations, to adjust designs to actual field conditions, and to determinethatthe grading is in general accordance with the recommendations of this report. Our personnel should perform sufficient testing of any fill placed to support our opinion as to whether compaction recommendations have been complied with. 7.2.2 Site Prenaration a. Non-exoansive Can: If the option of capping the building areas with imported, non-expansive fill is used, the capped area should include the area within a perimeter of five feet outside the building limits. The existing soil and bedrock in this area should be excavated to a depth of at least four feet below proposed slab subgrade, and the excavation bottom observed by our personnel. The excavation should then be brought to the design grade using uniformly compacted lifts of imported soil. The import should consist of well graded soil having an expansive index no greater that 20, based on U.B.C. Test 29-2, and should be checked by our office prior to importing. It may also be desired to use a similar recommendation in areas of curb, gutter, - - .- - - - - - - - - - - - - Puritan-Bennett '/,, Ehrlich-Rominger Job No. 05-7928-001-00-00 Log No. 9-1714 June 6, 1989 Page 13 sidewalks, and exterior slabs. This condition is further discussed in Section 7.5.8. b. Post-Tensioned Slabs: If post-tensioned slabs are used for the structure, then no special site preparation of the building area is considered necessary. Normal site preparation should apply, which consists of removal of any surface vegetation and debris, scarification of the upper 12 inches of soil, wetting the soil to approximately optimum moisture conditions, and compacting them to at least 90 percent relative compaction. c. Moisture Conditioninq: If the moisture conditioning option is chosen, the subgrade soil within the building area (as defined in option *'al*) should be brought to at least five percentage points over optimum moisture (ASTM D1557) in the upper four, feet of slab subgrade. This should be accomplished by removing the soil and bedrockmaterials in that zone, mixing the soils, and replacing them in uniformly compacted lifts at five percentage points over optimum. Because of the possible benefit of decreased expansive potential, the minimum compaction considered necessary is 87 percent of ASTM D1557. Presoaking the subgrade from the surface is not recommended at the site because of the very low permeability of the soil and bedrock, and because of the deep zone of soil to be treated. - - - - Puritan-Bennett Job No. 05-7928-001-00-00 c/0 Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 14 d. Other Ontions: As stated previously, the moisture conditioning recommendation is considered to have more associated risk than the other two options. An alternative to moisturetreatingthe existing soilwhichwould have less risk is to use lime treatment. In our opinion, this option would have a similar risk to the imported non-expansive option. Typical lime treatment would involve the thorough mixing of three to six percent of hydrated lime or quick lime into the existing soil. More specific recommendations can be provided upon request. e. Deco Fill Transitions: The surface soils within the Phase II building area should be prepared in accordance with one of the methods previously recommended. The deep foundation recommendation is only intended to mitigate movements related to settlements and not to reduce expansive soil effects. 7.2.3 Fill Comnaction: Except as specifically discussed previously under "Moisture Conditioninq", all fill and backfill to be placed in association with site development should be accomplished at slightly over optimum moisture conditions and using equipment that is capable of producing a uniformly compacted product. The minimum relative compaction recommended for fill is 90 percent of maximum - -. - - - - - - - - - - - - - - - - Puritan-Bennett Job No. 05-1928-001-00-00 '/, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 15 density based on ASTM D1557 (modified Proctor). Sufficient ObSeNatiOn and testing should be performed by the geotechnical consultant so that an opinion can be rendered as to the degree of compaction achieved. Representative samples of imported materials and on site soils should be tested by the geotechnical consultant in order to evaluate the maximum density, optimum moisture content, and where appropriate, shear strength, consolidation, and expansion characteristics of the soil. During grading operations, soil types other than those analyzed in the geotechnical reports may be encountered by the contractor. The geotechnical consultant should be notified to evaluate the suitability of these soils for use as fill and as finish grade soils. 7.2.4 Trench Backfill, All trench backfill should be compacted by mechanical means in uniform lifts of 8 to 12 inches. The backfill should be uniformly compacted to at least 90 percent of ASTM D1557. 7.3 Slone Stabilitv A large slope does currently exist along the north and east edges of the project site which was created as part of the original grading on the site. The stability of - - - - - - .- - .- - - - - - - - Puritan-Bennett Job No. 05-7928-001-00-00 '/, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 16 this slope was addressed by San Diego Geotechnical Consultants during testing and observation for grading. We are therefore not including additional slope stability recommendations. 7.4 Site Drainase Foundation and slab performance depends greatly on how well the runoff waters drain from the site. This is true both during construction and over the entire life of the structure. The ground surface around structures should be graded so that water flows rapidly away from the structures without ponding. The surface gradient needed to achieve this depends on the prevailing landscape. In general, we recommendthatpavementand lawn areas within five feet of buildings slope away at gradients of at least two percent. Densely vegetated areas should have minimum gradients of at least five percent away from buildings in the first five feet. Densely vegetated areas are considered those in which the planting type and spacing is such that the flow of water is impeded. Planters should be built so that water from them will not seep into the foundation, slab, or pavement areas. Site irrigation should be limited to the minimum necessary to sustain landscaping plants. Should excessive irrigation, waterline breaks, or unusually high rainfall occur, saturated zones or "perched" groundwater may develop in fill soils and distress to structures may occur. - -. - - - - - - - - - - - - .- - Puritan-Bennett '/, Ehrlich-Rominger June 6, 1989 f Job No. 05-7928-001-00-00 Log No. 9-1714 Page 17 7.5 Foundation Recommendations 7.5.1 General Expansive soils on the site create the risk of future differential movement of foundations and interior slabs. The previously discussed recommendations will serve to mitigate the future movements. Our recommendations are considered generally consistent with methods typically used in southern California. Other alternatives may be available. The foundation recommendations herein should not be considered to preclude more restrictive criteria of governing agencies or by the structural engineer. The design of the foundation system should be performed by the project structural engineer, incorporating the geotechnicalparameters described in the following sections. Movement of exterior slabs, curb, and gutters must be accepted when building on highly expansive soils. Differential movement in excess of one inch is possible. Reinforcement and control joints will reduce cracking associated with such movements. If such movements are not acceptable, then a non-expansive cap or lime treatment should be used. - -.. - .- ,- - - - - - - Puritan-Bennett Job NO. 05-7928-001-00-00 c/0 Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 18 7.5.2 Foundations on Non-exnansive Can If the building area is capped with non-expansive soil as recommended in Section 7.2.2, the following foundation design parameters should be applicable. Allowable Soil Bearing: 3,000 psf (allow a one- third increase for short- termwind or seismic loads) Minimum Footing Width: 12 inches Minimum Footing Depth: 18 inches Minimum Reinforcement: two no.4 bars at both top and bottom in continuous footings, or design as simply supported beam capable of supporting the applied loads over a span of 5 feet, whichever is greater. 7.5.3 Post-Tensioned Slabs A structurally designed, post-tensioned slab-on grade may be used to mitigate the effects of soil expansion. The system consists of a slab reinforced with tendons which are tensioned after the concrete is cured. This method is typically usedin conjunctionwith conventionally reinforced stiffening beams. We recommend the following design parameters, based on criteria of the Post- Tensioning Institute. Edge Moisture Variation, e, Center Lift: 6.0 ft. Edge Lift: 3.0 ft. - - - - - - - Puritan-Bennett Job No. 05-7928-001-00-00 c/0 Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 19 Differential Swell, y,,, Center Lift: 1.7 in. Edge Lift: 0.4 in. Differential Settlement: 0.7 in. Allowable Bearing Capacity: 2000 psf 7.5.4 Moisture Conditioned Buildina Pad The following design parameters are contingent upon moisture conditioning the soils within the building area as discussed in Section 7.2.2. Allowable Soil Bearing: 1,500 psf (allow a one- third increase for short- tennwind or seismic loads) Minimum Footing Width: 12 inches Minimum Footing Depth: 24 inches Minimum Reinforcement: two no.5 bars at both top and bottom in continuous footings,or design as simply supported beam capable of supporting the applied loads over a span of 8 feet, which-ever is greater. 7.5.5 Deev Foundations (Phases II & III) The structure which is currently planned for lot 44 is located across a deep cut/fill transition on the order of 45 feet. A substantial amount of differential settlement is expected to occur if this structure is founded on conventional shallow - .- - - - ,- - - - - - - - ,- Puritan-Bennett Job No. 05-7928-001-00-00 c/0 Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 20 footings. For this reason we recommend that the entire structure be founded on footings or caissons bearing in bedrock. Portions of the building which are placed over shallow fill may utilize the deepened footing option presented in section 7.5.5. Those portions of the buildings which are located over deeper fills should be supported by drilled caissons. The following recommendations are for the design of drilled caissons. Resistance to lateral loads are presented later in this report in section 7.5.8. Caisson tip pressure: 30,000 psf Minimum tip embedment: 4 feet (into undis- turbed bedrock) Minimum caisson diameter: 16 inches 7.5.6 Settlement The anticipated total and differential settlement for the proposed structure should be within tolerable limits providedthatthe recommendations of this report are followed. In general, total settlements are estimated to be less than one inch, and differential settlement is expected to be less than 3/4-inch. It is recommended that we review the actual foundation plans to evaluate the footing configurations and loading conditions. - - - - - .- - - - .- Puritan-Bennett Job NO. 05-7928-001-00-00 c/0 Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 21 1.5.7 Lateral Load Resistance Lateral loads against structures may be resisted by friction between the bottoms of footings and the supporting soil. A coefficient of friction of 0.3 is recommended for both fill and bedrock materials. Alternatively, a passive pressure of 400 pcf and 250 pcf is recommended for bedrock material and compacted fill, respectively. If friction and passive pressure are combined, the passive pressure value should be reduced by one- third. Lateral capacities for drilled piers can be provided at a later date once' approximate pile capacities and diameters have been determined. 7.5.8 On-Grade Slabs a. Interior slabs: Slabs should be designed by a structural engineer for the anticipated loading based on a modulus of subgrade reaction of 250 kips/ft3 for slabs on compacted non-ex- pansive imported soil, and 125 kips/ft3 for moisture conditioned native soil. In con- sideration of the expansive potential of the soil, slabs on moisture conditioned subgrade should be at least six inches thick and should be reinforced with at least #3 reinforcing bars on 18 inch centers, each way. Slabs on a non- expansive soil cap should be at least 5 inches thick and should be reinforced with at least _- - - - .- - - -. - Puritan-Bennett c/0 Ehrlich-Rominger June 6, 1989 Job No. 05-7928-001-00-00 Log No. 9-1714 Page 22 #3 reinforcing bars on 24 inch centers, each way. Crack control joints should be provided in all slabs, spaced on 15 to 20 foot centers. b. Moisture Protection for Slabs: Concrete slabs constructed on soil ultimately cause the moisture content to rise in the underlying soil. This results from continued capillary rise and the termination of normal evapotrans- piration. Because normal concrete is perme- able, the moisture will eventually penetrate the slab unless some protection is provided. This may cause mildewed carpets, lifting or discoloration of floor tile, or similar problems. To minimise these problems, suitable moisture protection measures should be used. Various alternatives exist, such as concrete toppings or additives, or synthetic moisture-resistant membranes. Information on the usage, instal- lation, and warranty should be obtained from the manufacturer if these products are used. The effectiveness of such measures can be improved by installing a capillary break under the membrane or damp-proofed slab. For a capillary break with a minimum thickness of ---~ four inches, the following criteria should be observed:'~'- - _- - - - - - - - - Puritan-Bennett c/0 Ehrlich-Rominger June 6, 1989 Job No. 05-7928-001-00-00 Log No. 9-1714 Page 23 1) It should consist of sand, gravel, or crushed rock having a maximum particle size of 3/4-inch or less: 2) Not more that 10% (by weight) should pass the No. 16 U.S. Standard Sieve: 3) Not more than 5% (by weight) should pass the No. 200 U.S Standard Sieve. If waterproofing membranes are installed beneath concrete slabs, at least one and one half inch of sand should be placed between the membrane and the slab to decrease the likelihood of curing problems in the concrete. c. Exterior Slabs: If exterior improvements such as slabs, sidewalks, and curb and gutter are placed directly over the on-site soil, some movement and cracking should be expected. Reinforcement and control joints will reduce the cracking and movement potential. As a minimal recommendation, slabs should be at least five inches in thickness and should be reinforced with at least 6"x6", W2.4 x W2.4 WWF (Welded Wire Fabric) placed at the mid- height of the slab. Crack control joints should be placed on at least 10 foot centers, each way. One inch of differential movement is not considered unusual, and more is _,~ ,-.~ .,_ ..- Puritan-Bennett c/0 Ehrlich-Rominger June 6. 1989 Job No. 05-7928-001-00-00 Log No. 9-1714 Page 24 possible. Differential movement between curbs and sidewalks can be decreased by dowelling the sidewalk into the curb. The sidewalk will typically rotate at the hinge point next to the curb. ._ .-.. - - Differential movement and cracking can be decreased if at least 2 feet of non-expansive soil is placed for slab subgrade. Lime treat- ment of the subgrade should also be effective. 7.5.9 Foundation Observation All foundation excavations should be observed by the geotechnical consultant prior to placement of forms, reinforcement, or concrete. The observa- tion will confirm that the soil conditions are as anticipated and that the intent of our recommen- dations have been complied with. The excavations should be trimmed to design dimensions and should be clear of all loose slough. 1.6 Earth Retainina Structures Because of the potential for high wall pressures result- ing from soil expansion, it is not recommended that walls be backfilled with on-site clays. Non-expansive imported soil should be used in the zone defined by a 1:l sloping plane, back from the base of the wall. Cantilever retaining walls backfilled with non-expansive soil should be designed for an active earth pressure -~ - - - -. _. - Puritan-Bennett Job No. 05-7928-001-00-00 '/, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 25 approximated by an equivalent fluid pressure of 35 lbs/ft'. The active pressure should be used for walls free to yield at the top at least 0.1 percent of the wall height. For walls restrained so that such movement is not permitted, an equivalent fluid pressure of 55 lbs/ft3 should be used, based on at-rest soil condit- ions. The above pressures do not consider any sloping backfill, surcharge loads, or hydrostatic pressures. If these are applicable, they will increase the lateral pressures on the wall and we should be contacted for additional recommendations. Retaining wall backfill should be compacted to at least 90 percent relative compaction, based on ASTM D1557. Backfill should not be placed until walls have achieved adequate structural strength. Heavy compaction equip- ment which could cause distress to walls should not be used. 7.7 Reactive Soils Our testing program indicated that the soils on-site contain sulphate contents high enough to be detrimental to type I portland cement. Therefore, we recommend that Type II cement be used in all concrete which will be in contact with soil. 7.8 Pavements In designing a suitable pavement section for the proposed parking areas and driveways we have assumed R- Value of 23. Traffic was assumed to fall into two - ,- - - - ~- Puritan-Bennett '/, Ehrlich-Rominger June 6, 1989 Job No. 05-7928-001-00-00 Log No. 9-1714 Page 26 categories: 1) Light traffic areas and passenger car parking (Traffic Index = 4.0), and 2) Access drives and truck routes (Traffic Index = 5.0). The project civil engineer should review these values to determine if they are appropriate. Based on these assumptions, the recommended pavement sections are as follows: Asphaltic Concrete Aggregate Base Thickness Thickness Parking areas T.I.= 4.0 3 inches 4.5 inches 1~5 Driving Lanes T.I.= 5.0 3 inches 7.5 inches IO,? I-C *- ,': ~A0 v"W"f ', d j , , 'A p ,,, ../ ! 3 I4 *ii, rl; = A- The upper 12 inches of pavement subgrade should be scar- ified, brought to approximately optimum moisture con- tent, and compacted to at least 95 percent of ASTM D- 1557. Aggregate base should conform to Section 26 of the California Department of Transportation Manual, and should be uniformly compacted to at least 95 percent relative compaction. 7.9 Review of Plans When the grading plans and foundation plans are devel- wed, they should be forwarded to the geotechnical consultant review. The recommendations of this report are based on assumptions regarding the proposed develop- ment. Our review will confirm these assumptions and evaluate if the intent of the recommendations of this report have been complied with. - - - _ - - - .- - -. _- .- - Puritan-Bennett Job NO. 05-7928-001-00-00 c/0 Ehrlich-Rominger Log NO. 9-1714 June 6. 1989 Page 27 8.0 LIMITATIONS OF INVESTIGATION Our investigation was performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable geotechnical consultants practicing in this or similar localities. No other warranty, expressed or implied, is made as to the conclusions and professional opinions in- cluded in this report. The samples taken and used for testing and the observations made are believed representative of the project site; how- ever, soil and geologic conditions can vary significantly between borings. As in most projects, conditions revealed by excavation may be at variance with preliminary findings. If this occurs, the changed conditions must be evaluated by the geotechnical consultant and additional recommendations made, if warranted. This report is issued with the understanding that it is the responsibility of the owner, or of his representative, to ensure that the information and recommendations contained herein are brought to the attention of the necessary design consultants for the project and incorporated into the plans, and the necessary steps are taken to see that the contractors carry out such recommendations in the field. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responsible for other than our own personnel on the site. - - - Puritan-Bennett Job No. 05-7928-001-00-00 '/, Ehrlich-Rominger Log No. 9-1714 June 6, 1989 Page 33 The findings of this report are valid as of the present date. However, changes in the condition of a property can occur with the passage of time, whether due to natural processes or the work of man on this or adjacent properties. In addition, changes in applicable or appropriate standards of practice may occur from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. There- fore, this report is subject to review and should not be relied upon after a period of three years. *** SAN DIEGO GEOTECHNICAL CONSULTANTS, INC. Erik J. Nelson, P.E. C44102 P.E. C40333 Registration Expires: 6-30-89 Registration ExpirLs: 3-31-91 Project Engineer Chief Engineer (Vice President) AFB/EJN/cf - -. - - - - APPENDIX A References References 1. Bowles, J. E. 1982, "Foundation Analysis and Design", McGraw Hill 2. Ploessel and Slosson, 1974, "Repeatable High Ground Acceleration From Earthguakest', California Geology, California Division of Mines and Geology, September. .- - 3. Seed, H. B., and Idriss, I. M., 1982, "Ground Motions and Soil Liquefaction During Earthquakes", Earthquake Engineering Research Institute, Berkeley, California. 4. San Diego Soils Engineering, April 1, 1988, "As Graded Geotechnical Report, Carlsbad Research Center, Phases III, IV, and V, Carlsbad, California", Job No. 05-2863- 006-00-10. - -- -. - ,- - - - - -~ - -- APPENDIX B Field Exploration - - - - .- - - - - - .~ - - - DEFINITION OF TERMS I FRACTION IS PRIMARY DlVlSlONS I SYMBOLSi SECONDARY DIVISIONS I QI.0.d OrIvolo or WOVOHUld m(xtoroo. lutfa or ~ gravokU*)lilt mUturo*. nomtkotk a - a. m hxv.y gr.volX. D,WOkO”d-OkY mlXt”tOX. Dhtk s SW w.,, 0r.d.d l xndx, grovofl~ randa. llttfa ar 110 tftma ,N .:; : ,) .I’.‘:. sp Poor(l D,.d.d #Ulda or DrOVOffY Iand& fm OI IlO ffll*m. “““““.a ) 5% FINES FRACTION IS SM sffw SIX. ~0nd-dH mfxturoo. non-Dhatfa thaa SC NO. 4 SIEVE SILTS AND CLAYS Llaufo LIMIT IS I cm- TY.” La- D ants, mkxoooua Or dlatomacmouo fine aandy R”’ [or silty *01f*. alaall *iIt*. CH fnorg~nfo c1.y‘ ot hfDh PlootkW fXt CIW& komio cfayo ot modfwn IO hlgh DfaattOltb OWWfiO ,y, Of IO1 to medfum Df~LtlO:t1. Drav*lly ,y ctxy*. IXOll CIOVX. HIGHLY ORGANIC SOILS pt Peat l d otftu klDfffy OrDmlk aoh. QRAIN SIZES IL18 AND CLAYS SAN0 I GRAVEL FINE 1 MEDIUM ( COARSE ) FINE 1 COARsE COBBLES SOULDERE 200 40 10 4 314’ 3. 12- U.S. STANDARD SERIES SIEVE CLEAR sOUARE SIEVE OPENINQE g GROUNDWATER LEVEL AT TtUE OF DRlLLfNQ; z QROUNDWATER LEVEL MEASURED LATER IN STANOPIPE. cl LOCATION OF SAMPLE TAKEN UsfNQ A STANDARD SPLIT TUBE SAMPLER. 2-fNCH 0.0.. l-S/S-fNCH I.D. DRIVEN WfTH”A t 4O.POUNO HAMMER FALLha 30-INCHES. I LOCATION OF SAMPLE TAKEN.fJsfNQ A fAoDlFfE0 CALIFORNIA SAMPLER. 3-tls-INCH 0.0.. WtTH 2-tI2-INCH I.D. LINER RINQS. DRIVEN USfNQ THE WEIQHT OF KELLY BAR (LARBE DIAMETER SORINQS) OR USINQ A 140 POUND HAMMER FALLINQ 30-INCHES (SUALL DIAMETER SORINQ): II LOCATION OF SAMPLE TAKEN fjsfNQ A S-INCH 0.0. THIN-WALLED TUSE SAMPLER (SHELBY TUBE1 HYDRAULICALLY PUSHED. LOCATION OF BULK SAMPLE TAKEN FROM AUQER CUTTINOS. KEY TO LOGS - UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D-2487) 08 NO.: DATE: FIQURE: 05-7928~~01~-00-00 JUNE 1989 B-l - - - - - - - - - - - - - - - - IATE OBSERVED: 4-14-89 METHOD OF DRILLING: 8" Hoh~ Stem Auaer 18 30 5( 2( - E = : @a !a :a :” 3 - - - iat - ;EVATION:N/A LOCATION: See Map LOG OF BORING NO. 1 Sheet 1 of 1 DESCRIPTION POINT LOMA FORMATION (Koll: Dark gray SILTSTONE, very hard, moist Trace of iron staining at 7’ - Total Depth 20’ No free water encountered at time of drilling Jiego Geotechnical Consultants, Inc. SOIL TEST - .- - - .- - - - - - - .- - - ,- IATE OBSERVED: 4-14-89 METHOD OF DRILLING: 8" Hollow Stem Awer LOGGEDBY:EJN GR~UNDELEV.~TION:N/A LOCATION: SeeMaD LOG OF BORING NO. 2 Sheet 1 of 1 DESCRIPTION SOIL TEST FILL: Gray/red/white mottled SILT, hard, moist, some siltstone, chunks and iron staining, trace of fine sand 48 68 race of organics at 10.5’ MOISTURE CONTENT-DRY DENSITY, IN PLACE PARTICLE SIZE ANALYSIS AlTERBERG LIMITS DIRECT SHEAR IN PLACE MOISTURI CONTENT-DRY DENSITY CONSOLIDATION POINT LOMA FORMATION (KDI~: Dark gray SILTSTONE, very hard, moist IN PLACE MOISTURE CONTENT-DRY DENSITY IO- Total Depth 28.5’ No free water encountered at time of drilling IS- $!;9:&)0 1-00-0O San Diego Geotechnical Consultants, In - - - - - - - - - - - - - - - - - - IATE OBSERVED: 4-14-89 METHOD OF DRILLING: 8" Hollow Stem Awer $7 76 28 5( - 1 ;: : et ‘i jj ! 5 I 1 I 1 - 3R( - ? k" 't- +z @Ill -I- 02 'e - - iar - ~EVATION:&!& LOCATION: See Mao LOG OF BORING NO. 3 Sheet 1 of 1 DESCRIPTION POINT LOMA FORMATION IKDI~: Gray to red brown, SILTSTONE, very hard, moist, trace of fine sand Dark gray at 7’ Darker with trace of gypsum at 17’ ,Very hard at 21’ Total Depth 21’ No free water encountered at time of drilling .z--- ts. SOIL TEST N PLACE MOISTURE :ONTENT-DRY )ENSITY :XPANSION INDEX N PLACE MOISTURE :ONTENT-DRY )ENSITY ‘ARTICLE SIZE LNALYSIS, J-TERBERG LIMITS )IRECT SHEAR -. -~ - - - - IATE OBSERVED: 4-14-89 METHOD OF DRILLING: 8" Hollow Stem Awer :D : t i f ! 1 i j i ; 7 ; 1: ! 9 i 1: 2 5: ‘3 E z : ;u !I 0: ;‘u: 3 - 1 1 - I , i : I 3R( - c $!" 'I- +z mw EC '8 - - WI I ! I I I I - - Sar .EVATION:N/A LOCATION: See MaD LOG OF BORING NO. 4 Sheet 1 of 1 SOIL TEST DESCRIPTION POINT LOMA FORMATION (Kill: Gray brown SILTSTONE, very hard, moist, trace of fine sand IXPANSION INDEX Sandier with iron stained lenses Large piece of gypsum in tip Total Depth 21’ No free water encountered at time of drilling -. .~ - - - - - - - - - - - )ATE OBSERVED: 4-14-89 METHOD OF DRILLING: 8" Hollow Stem Auaer 1 z : !I Ii 0: ;’ > 1 I 1 I i : ; : ’ ; : I - jar - .EVATION:N/A LOCATION: See MaD LOG OF BORING NO. 5 Sheet I of 1 DESCRIPTION POINT LOMA FORMATION (Kol) Gray SILTSTONE, very hard, moist, trace of iron staining @ 430 5’, Very hard, light gray cemented layer - I I! C : C : Total Depth 21’ No free water encountered at time of drilling SOIL TES N PLACE MOISTURE ZONTENT-DRY )ENSITY N PLACE MOISTURE :ONTENT-DRY )ENSITY N PLACE MOISTURE IONTENT-DRY )ENSITY N PLACE MOISTURE :ONTENT-DRY )ENSITY ‘ARTICLE SIZE iNALYSIS iTTERBERG LIMITS N PLACE MOISTURE :ONTENT-DRY )ENSITY Jiego Geotechnical Consultants, Inc. - - - .- - - - - - - - )ATE OBSERVED: 4-14-89 METHOD OF DRILLING: 8" Hollow Stem Auner !5- IO- i5- ,D : : / ; ! * : I 1 ; 7 j 1; j a !! ; : ki : d 1 !C 1 I = t 1 < ‘ I I I I I i : { : ’ $ : i I :R<. - G g" 'I- ;i= .w 35 =a 0 - - - .EVATION:N/A LOCATION: See Mao LOG OF BORING NO. 6 Sheet 1 of 1 DESCRIPTION POINT LOMA FORMATION (Koll: Gray brown SILTSTONE, very hard, moist, trace of iron staining Increased iron staining at 7’ Total Depth 21’ No free water encountered at time of drilling .I--!--, P ---.. I.--*- San Diego Geotecrlrllcal ~WISUIUIIWS, 1~1 SOIL TEST - - - APPENDIX C Laboratory Testing Program - - APPENDIX C LABORATORY TESTING - - - -~ - _~ - - - - - Selected representative samples of soils encountered were tested using test methods of the American Society for Testing and Mater- ials, or other generally accepted standards. A brief description of the tests performed follows: Classification: Soils were classified visually according to the Unified Soil Classification System. Visual classification was supplemented by laboratory testing of selected samples and clas- sification in accordance with ASTM D2487. The soil classificat- ions are shown on the Boring Logs. Particle Size Analysis: A particle size analysis was performed in accordance with ASTM D422. The grain size distribution was used to determine presumptive strength parameters used to develop foun- dation design criteria. The results are provided on the following Figures C-l to C-3. Expansion Test: Expansion tests were performed using Uniform Building Code Test Method 29-2. Test results are provided on the following Table C-l. Atterbera Limits: The liquid limit, plastic limit, and plasticity index of selected samples were determined in accordance with ASTM D4318. The test results are shown on Figures C-l to C-3. Consolidation Tests: Consolidation tests were performed on samp- les of the material encountered during field exploration to assess their compressibility under load. Testing was performed in accor- dance with ASTM D2435-80. Results are shown on Figure C-5. .-. - - -, - - - ,- Direct Shear Tests: Unconsolidated, undrained direct shear tests were performed in accordance with ASTM D3080. Remolded samples were remolded to 90 percent of the modified proctor density and tested in a saturated condition using normal loads of 1 ksf, 2 ksf, and 4 ksf. The results of the tests are presented in the attached Figure C-4. Moisture-Densitv RelationshiD: Laboratory tests were performed in accordance with ASTM D1557. A mechanically operated rammer was used during the compaction process. Test results are presented on Table C-2. In-Situ Moisture/Density: The in-place moisture content and dry unit weight of selected samples were determined using relatively undisturbed samples from the liner rings of a 2.5 inch ID Modified California Sampler. The dry unit weight and moisture content are shown on the attached Boring Logs. SUlfate Content, DH. and resistivity: The sulfate content, pH, and resistivity of selected samples were conducted to determine the reactivity potential of the soil with portland cement. Results of these tests are presented in Table C-3. R- Value: The prevailing Resistance (R) Value of the onsite soils was determined in accordance with California Department of transportation method 301. The results of this test is presented on figure C-6. I I I I \ I I I I ! ) / I I ( I I ~ GRAVEL I SAND COBBLES SILT CLAY COARSE FINE COARSE MEDIUM FINE SIEVE SIZES-U.S. STANDARD 70 Ii :: 60 z -I 60 2 : 40 z 0 30 GRAIN SIZE IN MILLIMETERS GRAIN SIZE IN MILLIMETERS BORING NO. DEPTH (FEET) SYMBOL LIQUID LIMIT PLASTICITY INDEX BORING NO.jDEPTH (FEET11 SYMBOL LIQUID LIMIT PLASTICITY INDEX CLASSIFICATION CLASSIFICATION B-2 B-2 I 4 4 I l l I 53 53 I 22 22 I MH-(HIGH PLASTICITY SILT) MH-(HIGH PLASTICITY SILT) I I I 1 I I I I I I 1 I I I I I I I / I / SIEVE SIZES-U.S. STANDARD 70 m 2 060 m 5 5o m zi (D 40 f D 30 20 10 GRAIN SIZE IN MILLIMETERS BORING NO. DEPTH (FEET) BYMBOL LIQUID LIMIT PLASTICITY INDEX CLABSIFICATION B-3 7 l 60 22 MH-(HIGH PLASTICITY SILT) I I I I I 1 I I I I I I I I / I j ) GRAVEL I SAND COBBLES SILT CLAY COARSE FINE COARSE MEDIUM FINE SIEVE SIZES--U.S. STANDARD GRAIN SIZE IN MILLIMETERS i 5 BORING NO. DEPTH (FEET) BYMBOL LIQUID LIMIT PLASTICITY INDEX CLASSIFICATION ” 0 B-5 6 a 54 16 MH-(HIGH PLASTICITY SILT) L: BORING DEPTH CO~p~Sl~N. ANGLE 0% SAMPLE DESCRIPTION NO. (FEET) FRICTION. s-2 I 2 I I PEAK #=32’ RESIDUAL 0=30.7’ c =71e OO I 1000 2000 3000 4000 6000 8000 1 NORMAL LOAD (PSR BORING DEPTH SAMPLE DESCRIPTION NO. (FEET) CO~;kl;fN. ANGLE OF, FRICTION. I 4000 3000 c z! E i E 2000 m / 2 E 2 c cl80 pa, 2 too0 00 1000 2000 3000 4000 6000 6000 NORMAL LOAD (PSF) JOB NO.: 0 SHEARING STRENGTH TEST FIGURE: - - - c-4 -~ - - -~ -. BORING NO. 2- SAMPLE DEPTH 8’ INITIAL DENSITY (PCF) 103.0 EXPLANATION INITIAL MOISTURE WL) 19.9 FIELD MOISTURE FINAL MOISTURE (%I 26.4 ---------- SAMPLE SATURATED INITIAL VOID RATIO 0.610 REBOUND !? 3.0 f5 z 2.0- 2 : 1.0 -0 1.0 2.0. 3.0 - 2 4.0. 2 F 2 6.0 - i 0 2 6.0 z 7.0- 8.0 - 9.0 - 10.06 ,o NORMAL LOAD (PSFI OB NO.: LOAD CONSOLIDATION TEST FIGURE: 05-7928-001-00-00 c-5 SAMPLE: “R-VALUE AT 303 PSI EXUDATION PRESSURE = 23 GRAIN SIZE DISTRISUTION SIEVE 1 AS RECEIVED / AS TESTED 3 ! 2% I 2 1”: 1 ,, I_ 49 ! =4 I =ij / =16 I I =30 i I =50 1 I ltlal I =2co I .05mm I cmnm; .Wl~~, LIWIO LIMIT ! PLASTIC LIMIT 1 PLASTICITY INDEX / SAND EOUIVALENT / EXUDATION PRESSURE psi )E NO.: IDATE: FIGURE: 05-7928-001-00-00 I JUNF 1989 C-6 -- -. APPENDIX D Standard Guidelines for Grading Projects - - - - _- - - - 2. STANDARD GUIDELINES FOR GRADING, PROJECTS GENERAL 1.1 1.2 1.3 1.4 1.5 1.6 Representatives of the Geotechnical Consultant should be present on-site during grading operations in order to make observations and perform tests so that professional opinions can be developed. The opinion will address whether grading has proceeded in accordance with the Geotechnical Consultant's recommendations and applicable project specifications: if the site soil and geologic conditions are as anticipated in the preliminary investigation: and if additional recommendations are warranted by any unexpected site conditions. Services do not include supervision or direction of the actual work of the contractor, his employees or agents. The guidelines contained herein and the standard details attached hereto represent this firm's standard recommendations for grading and other associated operations on construction projects. These guidelines should be considered a portion of the report to which they are appended. All plates attached hereto shall be considered as part of these guidelines. The Contractor should not vary from these guidelines without prior recommendation by the Geotechnical Consultant and the approval of the Client or his authorized representative. These Standard Grading Guidelines and Standard Details may be modified and/or superseded by recommendations contained in the text of the preliminary geotechnical report and/or subsequent reports. If disputes arise out of the interpretation of these grading guidelines or standard details, the Geotech- nical Consultant should determine the appropriate interpretation. DEFINITIONS OF TERMS 2.1 ALLUVIUM -- Unconsolidated detrital deposits resulting from flow of water. including sediments deposited in river beds, canyons, flood plains, lakes, fans at the foot of slopes and estuaries. Standard Guidelines for Grading Projects Page 2 - - - - _- -. 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 AS-GRADED (AS-BUILT) -- The surface and subsurface conditions at completion of grading. BACKCUT -- A temporary construction slope at the rear of earth retaining structures such as buttresses, shear keys, stabilization fills or retaining walls. BACKDRAIN -- Generally a pipe and gravel or similar drainage system placed behind earth retaining structures such buttresses, stabilization fills. and retaining walls. BEDROCK -- A more or Less solid, relatively undis- turbed rock in place either at the surface or beneath superficial deposits of soil. BENCH -- A relatively level step and near vertical rise excavated into sloping ground on which fill is to be placed. BORROW (Import) -- Any fill material hauled to the project site from off-site areas. BUTTRESS FILL -- A fill mass, the configuration of which is designed by engineering calculations to retain slope conditions containing adverse geologic features. A buttress is generally specified by minimum key width and depth and by maximum backcut angle. A buttress normally contains a backdrainage system. CIVIL ENGINEER -- The Registered Civil Engineer or consulting firm responsible for preparation of the grading plans, surveying and verifying as-graded topographic conditions. COLLUVIUM -- Generally loose deposits usually found near the base of slopes and brought there chiefly by gravity through slope continuous downhill creep (also see Slope Wash). COMPACTION -- Is the densification of a fill by mechanical means. CONTRACTOR -- A person or company under contract or otherwise retained by the Client to perform demolation. grading and other site improvements. Standard Guidelines for Grading Projects Page 3 .- - - - - 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22 2.23 DEBRIS -- All products of clearing, grubbing, demolition, contaminated soil material unsuitable for reuse as compacted fill and/or any other material so designated by the Geotechnical Consultant. ENGINEERING GEOLOGIST -- A Geologist holding a valid certificate of registration in the specialty of Engineering Geology. ENGINEERED FILL -- A fill of which the Geotechnical Consultant or his representative, during grading, has made sufficient tests to enable him to conclude that the fill has been placed in substantial compliance with the recommendations of the Geotechnical Consultant and the governing agency requirements. EROSION -- The wearing away of the ground surface as a result of the movement of wind, water, and/or ice. EXCAVATION -- The mechanical removal of earth materials. EXISTING GRADE -- The ground surface configuration prior to grading. FILL -- Any deposits of soil. rock, soil-rock blends or other similar materials placed by man. FINISH GRADE -- The ground surface configuration at which time the surface elevations conform to the approved plan. GEOFABRIC -- Any engineering textile utilized in geotechnical applications including subgrade stabilization and filtering. GEOLOGIST -- A representative of the Geotechnical Consultant educated and trained in the field of geology. GEOTECHNICAL CONSULTANT -- The Geotechnical Engineer- ing and Engineering Geology consulting firm retained to provide technical services for the project. For the purpose of these guidelines, observations by the Geotechnical Consultant include observations by the Geotechnical Engineer, Engineering Geologist and those performed by persons employed by and responsible to the Geotechnical Consultants. - Standard Guidelines for Grading Projects Page 4 - - - - - - - - .- 2.24 2.25 2.26 2.27 2.28 2.29 2.30 2.31 2.32 2.33 2.34 GEOTECHNICAL ENGINEER -- A licensed Civil Engineer who applies scientific methods, engineering principles and professional experience to the acquisition, inter- pretation and use of knowledge of materials of the earth's crust for the evaluation of engineering problems. Geotechnical Engineering encompasses many of the engineering aspects of soil mechanics, rock mechanics, geology. geophysics, hydrology and related sciences. GRADING -- Any operation consisting of excavation, filling or combinations thereof and associated operations. LANDSLIDE DEBRIS -- Material, generally porous and of low density, produced from instability of natural of man-made slopes. MAXIMUM DENSITY -- Standard laboratory test for maximum dry unit weight. Unless otherwise specified, the maximum dry unit weight shall be determined in accordance with ASTM Method of Test D1557. OPTIMUM MOISTURE -- Test moisture content at the maximum density. RELATIVE COMPACTION -- The degree of compaction (expressed as a percentage) of dry unit weight of a material as compared to the maximum dry unit weight of the material. ROUGH GRADE -- The ground surface configuration at which time the surface elevations approximately conform to the approved plan. SITE -- The particular parcel of land where grading is being performed. SHEAR KEY -- Similar to buttress, however, it is generally constructed by excavating a slot within a natural slope in order to stabilize the upper portion of the slope without grading encroaching into the lower portion of the slope. SLOPE -- Is an inclined ground surface the steepne,ss of which is generally specified as a ratio of horizontal:vertical (e.g., 2:l). SLOPE WASH -- Soil and/or rock material that has been transported down a slope by mass wasting assisted by runoff water not confined by channels (also see Colluvium). - - Standard Guidelines for Grading Projects Page 5 2.35 2.36 2.37 2.38 2.39 2.40 2.41 2.42 2.43 SOIL -- Naturally occurring deposits of sand, silt, clay, etc., or combinations thereof. SOIL ENGINEER -- Licensed Civil Engineer experienced in soil mechanics (also see Geotechnical Engineer). STABILIZATION FILL -- A fill mass, the configuration of which is typically related to slope height and is specified by the standards of practice for enhancing the stability of locally adverse conditions. A stabilization fill is normally specified by minimum key width and depth and by maximum backcut angle. A stabilization fill may or may not have a backdrainage system specified. SUBDRAIN -- Generally a pipe and gravel or similar drainage system placed beneath a fill in the alignment of canyons or former drainage channels. SLOUGH -- Loose, noncompacted fill material generated during grading operations. TAILINGS -- Nonengineered fill which accumulates on or adjacent to equipment haul-roads. TERRACE -- Relatively level step constructed in the face of graded slope surface for drainage control and maintenance purposes. TOPSOIL -- The presumably fertile upper zone of soil which is usually darker in color and loose. WINDROW -- A string of large rock buried within engineered fill in accordance with guidelines set forth by the Geotechnical Consultant. 3. SITE PREPARATION 3.1 Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods, stumps, trees, roots to trees and otherwise deleterious natural materials from the areas to be graded. Clearing and grubbing should extend to the outside of all proposed excavation and fill areas. 3.2 Demolition should include removal of buildings, struc- tures, foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining shafts, tunnels, etc.) and other man-made surface and subsurface improvements .- - -. - - - - - - - - - - Standard Guidelines for Grading Projects Page 6 from the areas to be graded. Demolition of utilities should include proper capping and/or re-routing pipe- lines at the project perimeter and cutoff and capping of wells in accordance with the requirements of the governing authorities and the recommendations of the Geotechnical Consultant at the time of demolition. 3.3 Debris generated during clearing, grubbing and/or demolition operations should be wasted from areas to be graded and disposed off-site. Clearing, grubbing and demolition operations should be performed under the observation of the Geotechnical Consultant. 4. SITE PROTECTION 4.1 4.2 4.3 4.4 4.5 The Contractor should be responsible for the stability of all temporary excavations. Recommendations by the Geotechnical Consultant pertaining to temporary excavations (e.g., backcuts) are made in consideration of stability of the completed project and, therefore, should not be considered to preclude the responsibil- ities of the Contractor. Recommendations by the Geotechnical Consultant should not be considered to preclude more restrictive requirements by the regulating agencies. Precautions should be taken during the performance of site clearing, excavations and grading to protect the work site from flooding, ponding or inundation by poor or improper surface drainage. Temporary provisions should be made during the rainy season to adequately direct surface drainage away from and off the work site. During periods of rainfall the Geotechnical Consultant should be kept informed by the Contractor as to the nature of remedial or preventative work being performed (e.g., pumping, placement of sandbags or plastic sheeting, other labor. dozing. etc.). Following periods of rainfall. the Contractor should contact the Geotechnical Consultant and arrange a review of the site in order to visually assess rain related damage. The Geotechnical Consultant may also recommend excavations and testing in order to aid in his assessments. Rain related damage should be considered to include, but may not be limited to, erosion, silting, saturation, swelling, structural distress and other adverse conditions identified by the Geotechnical Standard Guidelines for Grading Projects Page 7 - - - -. - Consultant. Soil adversely affected should be classified as Unsuitable Materials and should be subject to overexcavation and replacement with compacted fill or other remedial grading as recommended by the Geotechnical Consultant. 5. EXCAVATIONS 5.1 UNSUITABLE MATERIALS 5.1.1 Materials which are unsuitable should be excavated under observation and recommendations of the Geotechnical Consultant. Unsuitable materials include, but may not be limited to, dry, loose. soft, wet, organic compressible natural soils and fractured, weathered, soft bedrock and nonengineered or otherwise deleterious fill materials. 5.1.2 Material identified by the Geotechnical Consultant as unsatisfactory due to its moisture conditions should be overexcavated. watered or dried, as needed. and thoroughly blended to a uniform near optimum moisture condition (as per guidelines reference 7.2.1) prior to placement as compacted fill. 5.2 CUT SLOPES 5.2.1 Unless otherwise recommended by the Geotech- nical Consultant and approved by the regulating agencies. permanent cut slopes should not be steeper than 2:l (horizontal:vertical). 5.2.2 If excavations for cut slopes expose loose. cohesionless, significantly fractured or otherwise unsuitable material, overexcavation and replacement of the unsuitable materials with a compacted stabilization fill should be accomplished as recommended by the Geotechnical Consultant. Unless otherwise specified by the Geotechnical Consultant. stabilization fill construction should conform to the requirements of the Standard Details. 5.2.3 The Geotechnical Consultant should review cut slopes during excavation. The Geotechnical Consultant should be notified by the contractor prior to beginning slope excavations. - -- - Standard Guidelines for Grading Projects - Page 8 - - 5.2.4 If, during the course of grading. adverse or potentially adverse geotechnical conditions are encountered which were not anticipated in the preliminary report, the Geotechnical Consultant should explore, analyse and make recommen- dations to treat these problems. - _- 6. COMPACTED FILL All fill materials should be compacted to at least 90 percent of maximum density (ASTM D1557) unless otherwise recommended by the Geotechnical Consultant. 6.1 PLACEMENT .- - - - - ,- - - - - 6.1.1 Prior to placement of compacted fill, the Contractor should request a review by the Geotechnical Consultant of the exposed ground surface. Unless otherwise recommended, the exposed ground surface should then be scarified (6-inches minimum), watered or dried as needed, thoroughly blended to achieve near optimum moisture conditions, then thoroughly compacted to a minimum of 90 percent of the maximum density. 6.1.2 Compacted fill should be placed in thin horizontal lifts. Each lift should be watered or dried as needed, blended to achieve near optimum moisture conditio,ns then compacted by mechanical methods to a minimum of 90 percent of laboratory maximum dry density. Each lift should be treated in a like manner until the desired finished grades are achieved. 6.1.3 When placing fill in horizontal lifts adjacent to areas sloping steeper than 5:l (horizontal: vertical). horizontal keys and vertical benches should be excavated into the adjacent slope area. Keying and benching should be sufficient to provide at least 6-foot wide benches and a minimum of 4-feet of vertical bench height within the firm natural ground, firm bedrock or engineered compacted fill. No compacted fill should be placed in an area subsequent to keying and benching until the area has been reviewed by the Geotechnical Consultant. Material generated by the benching operation should be moved sufficiently away from the bench area to allow for the recommended review of the horizontal bench prior to placement - - - - - ,- - - - - - - - Standard Guidelines for Grading Projects Page 9 fill. Typical keying and benching details have been included within the accompanying Standard Details. 6.1.4 Within a single fill area where grading procedures dictate two or more separate fills, temporary slopes (false slopes) may be created. When placing fill adjacent to a false slope, benching should be conducted in the same manner as above described. At least a 3-foot vertical bench should be established within the firm core adjacent approved compacted fill prior to placement of additional fill. Benching should proceed in at least 3-foot vertical increments until the desired finished grades are achieved. 6.1.5 Fill should be tested for compliance with the recommended relative compaction and moisture conditions. Field density testing should conform to accepted test methods. Density testing frequency should be adequate for the geotechnical consultant to provide professional opinions regardings fill compaction and adherence to recommendations. Fill found not to be in conformance with the grading recommendation should be removed or otherwise handled as recommended by the Geotechnical Consultant. 6.1.6 The Contractor should assist the Geotechnical Consultant and/or his representative by digging test pits for removal determinations and/or for testing compacted fill. 6.1.7 As recommended by the Geotechnical Consultant, the Contractor may need to remove grading equipment from an area being tested if personnel safety is considered to be a problem. 6.2 MOISTURE 6.2.1 For field testing purposes "near optimum" moisture will vary with material type and other factors including compaction procedure. "Near optimum" may be specifically recommended in Preliminary Investigation Reports and/or may be evaluated during grading. 6.2.2 Prior to placement of additional compacted fill following an overnight or other grading delay. the exposed surface or previously compacted - - - - .- Standard Guidelines for Grading Projects Page 10 fill should be processed by scarification, watered or dried as needed, thoroughly blended to near-optimum moisture conditions, then recompacted to a minimum of 90 percent of laboratory maximum dry density. Where wet, dry, or other unsuitable materials exist to depths of greater than one foot, the unsuitable materials should be overexcavated. 6.2.3 Following a period of flooding, rainfall or overwatering by other means, no additional fill should be placed until damage assessments have been made and remedial grading performed as described under Section 5.6 herein. 6.3 FILL MATERIAL 6.3.1 6.3.2 6.3.3 6.3.4 Excavated on-site materials which are considered suitable to the Geotechnical Consultant may be utilized as compacted fill, provided trash, vegetation and other deleterious materials are removed prior to placement. Where import fill materials are required for use on-site, the Geotechnical Consultant should be notified in advance of importing, in order to sample and test materials from proposed borrow sites. No import fill materials should be delivered for use on-site without prior sampling and testing notification by Geotechnical Consultant. Where oversized rock or similar irreducible material is generated during grading, it is recommended, where practical, to waste such material off-site or on-site in areas designated as "nonstructural rock disposal areas". Rock placed in disposal areas should be placed with sufficient fines to fill voids. The rock should be compacted in lifts to an unyielding condition. The disposal area should be covered with at least three feet of compacted fill which is free of oversized material. The upper three feet should be placed in accordance with the guidelines for compacted fill herein. Rocks 12 inches in maximum dimension and smaller may be utilized within the compacted fill, provided they are placed in such a manner -- - - - - - - - - Standard Guidelines for Grading Projects Page 11 that nesting of the rock is avoided. Fill should be placed and thoroughly compacted over and around all rock. The amount of rock should not exceed 40 percent by dry weight passing the 3/4-inch sieve size. The 12-inch and 40 percent recommendations herein may vary as field conditions dictate. 6.3.5 Where rocks or similar irreducible materials of greater than 12 inches but less than four feet of maximum dimension are generated during grading, or otherwise desired to be placed within an engineered fill, special handling in accordance with the accompanying Standard Details is recommended. Rocks greater than four feet should be broken down or disposed off-site. Rocks up to four feet maximum dimension should be placed below the upper 10 feet of any fill and should not be closer than ZO-feet to any slope face. These recommen- dations could vary as locations of improvements dictate. Where practical, oversized material should not be placed below areas where structures or deep utilities are proposed. Oversized material should be placed in windrows on a clean, overexcavated or unyielding compacted fill or firm natural ground surface. Select native or imported granular soil (S-E. 30 or higher) should be placed and thoroughly flooded over and around all windrowed rock, such that voids are filled. Windrows of oversized material should be staggered so that successive strata of oversized material are not in the same vertical plane. 6.3.6 It may be possible to dispose of individual larger rock as field conditions dictate and as recommended by the Geotechnical Consultant at the time of placement. 6.3.7 The construction of a "rock fill" consisting primarily of rock fragments up to two feet in maximum dimension with little soil material may be feasible. Such material is typically generated on sites where extensive blasting is required. Recommendations for construction of rock fills should be provided by the Geotechnical Consultant on a site-specific basis. Standard Guidelines for Grading Projects Page 12 .- - - - - - - - - .- - - - .- 6.3.8 During grading operations, placing and mixing the materials from the cut and/or borrow areas may result in soil mixtures which possess unique physical properties. Testing may be required of samples obtained directly from the fill areas in order to determine conformance with the specifications. Processing of these additional samples may take two or more working days. The Contractor may elect to move the operation to other areas within the project, or may continue placing compacted fill pending laboratory and field test results. Should he elect the second alternative, fill placed is done so at the Contractor's risk. 6.3.9 Any fill placed in areas not previously reviewed and evaluated by the Geotechnical Consultant may require removal and recom- paction. Determination of overexcavations should be made upon review of field conditions by the Geotechnical Consultant. 6.4 FILL SLOPES 6.4.1 Permanent fill slopes should not be constructed steeper than 2:l (horizontal to vertical), unless otherwise recommended by the Geotech- nical Consultant and approved by the regulating agencies. 6.4.2 Fill slopes should be compacted in accordance with these grading guidelines and specific report recommendations. Two methods of slope compaction are typically utilized in mass grading, lateral over-building and cutting back, and mechanical compaction to grade (i.e. sheepsfoot roller backrolling). Constraints such as height of slope, fill soil type, access, property lines, and available equipment will influence the method of slope construction and compaction. The geotechnical consultant should be notified by the contractor what method will be employed prior to slope construction. Slopes utilizing over-building and cutting back should be constructed utilizing horizontal fill lifts (reference Section 6) with compaction equipment working as close to the edge as prac- tical. The amount of lateral over-building will vary as field conditions dictiate. Compaction testing of slope faces will be required and - - - - - Standard Guidelines for Grading Projects Page 13 reconstruction of the slope may result if testing does not meet our recommendations. Mechanical compaction of the slope to grade during construction should utilize two types of compactive effort. First, horizontal fill lifts should be compacted during fill placement. This equipment should provide compactive effort to the outer edge of the fill slope. Sloughing of fill soils should not be permitted to drift down the slope. Secondly, at intervals not exceeding four feet in vertical slope height or the capability of available equipment, whichever is less, fill slopes should be backrolled with a sheepsfoot-type roller. Moisture conditions of the slope fill soils should be maintained throughout the compaction process. Generally upon slope completion, the entire slope should be compacted utilizing typical methods, (i.e. sheepsfoot rolling, bulldozer tracking, or rolling with rubber-tired heavy equipment). Slope construction grade staking should be removed as soon as possible in the slope compaction process. Final slope compaction should be performed without grade sakes on the slope face. In order to monitor slope construction procedures, moisture and density tests will be taken at regular intervals. Failure to achieve the desired results will likely result in a recommendation by the Geotechnical Consultant to overexcavate the slope surfaces followed by reconstruction of the slopes utilizing over- filling and cutting back procedures or further compactive effort with the conventional backrolling approach. Other recommendations may also be provided which would be commensurate with field conditions. 6.4.3 Where placement of fill above a natural slope or above a cut slope is proposed, the fill slope configuration as presented in the accompanying Standard Details should be adopted. 6.4.4 For pad areas above fill slopes, positive drainage should be established away from the top-of-slope, as designed by the project civil engineer. Standard Guidelines for Grading Projects Page 14 - - - - - - - - - - - -. - 6.5 OFF-SITE FILL 6.5.1 Off-site fill should be treated in the same manner as recommended in the specifications for site preparation, excavation, drains, compaction, etc. 6.5.2 Off-site canyon fill should be placed in preparation for future additional fill, as shown in the accompanying Standard Details. 6.5.3 Off-site fill subdrains temporarily terminated (up canyon) should be surveyed for future relocation and connection. 6.6 TRENCH BACKFILL 6.6.1 Utility trench backfill should, unless other- wise recommended, be compacted by mechanical means. Unless otherwise recommended, the degree of compaction should be a minimum of 90 percent of maximum density (ASTM D1557). 6.6.2 Backfill of exterior and interior trenches extending below a 1:l projection from the outer edge of foundations should be mechanically compacted to a minimum of 90 percent of the laboratory maximum density. 6.6.3 Within slab areas, but outside the influence of foundations, trenches up to one foot wide and two feet deep may be backfilled with sand (S.E. > 3D), and consolidated by jetting, flooding or by mechanical means. If on-site materials are utilized, they should be wheel-rolled, tamped or otherwise compacted to a firm condition. For minor interior trenches, density testing may be deleted or spot testing may be elected if deemed necessary, based on review of backfill operations during construction. 6.6.4 If utility contractors indicate that it is undesirable to use compaction equipment in close proximity to a buried conduit, the Contractor may elect the utilization of light weight mechanical compaction equipment and/or shading of the conduit with clean, granular material, (S.E. > 30) which should be thoroughly moistened in the trench, prior to - ..~ - - - ~- - - - - - - - Standard Guidelines for Grading Projects Page 15 initiating mechanical compaction procedures. Other methods of utility trench compaction may also be appropriate, upon review of the Geotechnical Consultant at the time of construction. 6.6.5 In cases where clean granular materials are proposed for use in lieu of native materials or where flooding or jetting is proposed, the procedures should be considered subject to review by the Geotechnical Consultant. 6.6.6 Clean granular backfill and/or bedding are not recommended in slope areas unless provisions are made for a drainage system to mitigate the potential build-up of seepage forces and piping. 7. DRAINAGE 7.1 7.2 7.3 7.4 Canyon subdrain systems recommended by the Geotechnical Consultant should be installed in accordance with the Standard Details. Typical subdrains for compacted fill buttresses, slope stabilizations or sidehill masses, should be installed in accordance with the specifications of the accompanying Standard Details. Roof, pad and slope drainage should be directed away from slopes and areas of structures to disposal areas via suitable devices designed by the project civil engineer (i.e., gutters, downspouts, concrete swales, area drains, earth swales, etc.). Drainage patterns established at the time of fine grading should be maintained throughout the life of the project. Property owners should be made aware that altering drainage patterns can be detrimental to slope stability and foundation performance. 8. SLOPE MAINTENANCE 8.1 LANDSCAPE PLANTS In order to decrease erosion surficial slope stability problems, slope planting should be accomplished at the completion of grading. Slope planting should consist of deep-rooting vegetation requiring little watering. A Landscape Architect would be the test party to consult regarding actual types of plants and planting configuration. Standard Guidelines for Grading Projects Page 16 8.2 IRRIGATION 8.2.1 Slope irrigation should be minimized. If automatic timing devices are utilized on irrigation systems, provisions should be made for interrupting normal irrigation during periods of rainfall. 8.2.2 Property owners should be made aware that overwatering of slopes is detrimental to slope stability and may contribute to slope seepage, erosion and siltation problems in the subdivision. - - - - - Rev S/88 ~. -~~ -~ - - - - - - - - - .- 16’ MlNlMUM 4’ DIAMETER PERFORATED PIPE BACKDRAIN 4. DIAMETER NON-PERFORATED- ? PIPE LATERAL DRAIN SLOPE PER PLANS \ - FT -BENCHING \’ \PROVlDE BACK DRAIN PER BACKDRAIN DETAIL. AN ADDITIONAL BACKDRAIN At MID-SLOPE WILL BE REOUIRED FOR SLOPE IN EXCESS OF 40 FEET HIQH. KEY-DIMENSION PER SOILS ENGINEER (GENERALLY 112 SLOPE HEIGHT. 15’ MINIMUM) TYPICAL STASILIZATION FILL DETAIL OB NO.: DATE: FIGURE: 05-7928-0012OOrOO JUNF IQ89 1 -~ - - - _- ._ - - 16’ MINIMUM 4’ DIAMETER PERFORATED PIPE BACKDRAIN 4’ DIAMETER NON-PERFORATED PIPE LATERAL DRAIN SLOPE PER PLAN PROVIDE SACKDRAIN PER BACKDRAIN DETAIL. AN ADDITIONAL BACKDRAIN AT MID-SLOPE WILL BE REQUIRED FOR SLOPE IN EXCESS OF 40 FEET HIQH. KEY-DIMENSION PER SOILS ENQINEER TYPICAL BUTTRESS FILL DETAIL OB NO.: OATE: FIGURE: - - -- JUNE 1989 2 - - - - NATURAL QROUND PROPOSED QRADING COMPACTED FILL PROVIDE SACKDRAIN PER SACKDRAIN DETAIL. AN ADDITIONAL BACKDRAIN AT MID-SLOPE WILL SE REQUIRED FOR SACK SLOPES IN EXCESS OF 40 FEET HIGH. LOCA- BASE WIDTH ‘W’ DETERMINED BY SOILS ENGINEER TIONS OF SACKDRAINS AND OUTLETS PER SOILS ENGINEER ANDIOR EN- GINEERING GEOLOGIST DURING GRADING. TYPICAL SHEAR KEY DETAIL JO8 NO.: DATE: FIGURE: - - 001-00-00 JlJNF 1939 3 _ - - . . - ,- - - - .-~ -- FINAL LIMIT OF DAYLIGHT /- OVEREXCAVATE EXCAI YAT ION L 20’ MAXIMUM i FINISH PAD OVEREXCAVATE 3’ AND WITH COMPACTED LTYPICAL BENCHING 2’ MINIMUM OVERBURDEN (CREEP-PRONE) PROVIDE BACKDRAIN PER BACKDRAIN DETAIL. LOCATION OF SACKDRAIN AND OUTLETS PER SOILS ENQINEER ANDIOR ENQINEERING QEOLOGIST DURING Eqf 3 BEDROCK \\ QRADING /- EOUIPMENT WIDTH (MINIMUM 15’1 DAYLIGHT SHEAR KEY DETAIL 10s NO.: I DATE: 1 FIGURE: - - - - - - . ~,-. - .- ,- BENCHING FILL OVER NATURAL I SURFACE OF FIRM EARTH MATERIAL FILL SLOPE IO’ z TYPICAL IO’ MIN. (INCLINED 2x MIN. INTO SLOPE) BENCHING FILL OVER CUT FINISH FILL SLOPE SURFACE OF FIRM EARTH MATERIAL 15’ MIN. OR STABILITY EQUIVALENT PER SOIL ENGINEERING (INCLINED 2x MIN. INTO SLOPE) BENCHING FOR COMPACTED FILL DETAIL JOB NO.: DATE: FIQURE: 05-7928-001-00-00 JUNE 1989 5 - - - - - _~ - _- - .- FINISH SURFACE SLOPE 3 FT3 MINIMUM PER LINEAL FOOT APPROVED FILTER ROCK* AOMPACTGD FILL , 4’ MINIMUM APPROVED PERFORATED PIPE** *,;,“,b”l,“,“,“;:^,“ER SPACED PER SOIL ENQINEER REOUIRE- MENTS DURINQ GRADING I LTYPICAL BENCHINO DETAIL A-A TEMPORARY FILL LEVEL COMPACTED 4’ MINIMUM DIAMETER APPROVED SOLID OUTLET PIPE 12’ MINIMUM COVER 12. MINIMUM *FILTER ROCK TO MEET FOLLOWING SPECIFICATIONS OR APPROVED EQUAL: SIEVE PERCENTAGE PASSINQ **APPROVED PIPE TYPE: lm 100 314. 90-100 SCHEDULE 40 POLYVINYL CHLORIDE 3/s* 40-100 (P.V.C.) OR APPROVED EOUAL. NO.4 26-40 MINIMUM CRUSH STRENGTH 1000 PSI. NO.30 5-1s NO.50 o-7 NO.200 o-3 TYPICAL BACKDRAIN DETAIL JOB NO.: DATE: FIGURE: - -~ -~ - - - - - - - - - - - - - -~ FINISH SURFACE SLOPE MINIMUM 3 FT3 PER LINEAL FOOT OPEN QRADED AQQREQATE* TAPE AND SEAL AT CONTACT )(\COMPACTED FILL / SUPAC S-P FABRIC OR APPROVED EGUAL 4” MINIMUM DIAMETER SOLID OUTLET PIPE SPACED PER SOIL ENQINEER REDUIREMENTS 4” MINIMUM APPROVED PERFORATED PIPE (PERFORATIONS DOWN) MINIMUM 2% GRADIENT TO OUTLET BENCH INCLINED BENCHING TOWARD DRAIN DETAIL A-A /- TEMPORARY FILL LEVEL I 1 MINIMUM 12” COVER COMPACTED BACKFILL MINIMUM 4” DIAMETER APPROVED SOLID OUTLET PIPE -12’ ---Jr MINIMUM *NOTE: AGGREGATE TO MEET FOLLOWING SPECIFICATIONS OR APPROVED EGUAL: SIEVE SIZE PERCENTAGE PASSING I 112” 100 I’ 5-40 314” O-17 318” o-7 NO. 200 o-3 BACKDRAIN DETAIL (GEOFABRIC) 08 NO.: DATE: FIGURE: 05-7928-001-00-00 JUNF 1989 7 -~ ,~. - - - - -. - - - ,- CANYON SUBDRAIN DETAILS L SURFACE OF FIRM EARTH ---- ----- /’ TYPICAL BENCHING REMOVE UNSUITABLE MATERIAL INCLINE TOWARD DRAIN SEE DETAILS BELOW TRENCH DETAIL 6. M - OPTIONAL V-DITCH DETAIL SUPAC 8-P FABRIC IINI i MUM 01 --- / 24’ IINIMUM ILAP - -MINIMUM 6 FT3 PER LINEAL FOOT OF APPROVED DRAIN MATERIAL /SUPAC 5-P FABRIC OR APPROVED EQUAL DRAIN MATERIAL SHOULD CONSIST OF MINUS 1.6’. MINUS I’, OR MINUS .75* CRUSHED ROCK -24’ -MINIMUM 6 FT3 PER LINEAL FOOT MINIMUM OF APPROVED DRAIN MATERIAL 60’ TO SO’ ADD MINIMUM 4’ DIAMETER APPROVED PERFORATED PIPE WHEN LARGE FLOWS ARE ANTICIPATED APPROVED PIPE TO BE SCHEDULE 40 POLY-VINYL- CHLORIDE (P.V.C.) OR APPROVED EGUAL. MINIMUM CRUSH STRENGTH 1000 Dai. GEOFASRIC SUBDRAIN OS NO.: DATE: FIGURE: 05-7~2%-001-00-on JUNE 198s 8 FINAL GRADE TOE OF SLOPE SHOWN nu nm.o,uo PLAN “,. - . . . . -.._- . ----- - -, ,- COMPETENT EARTH MATERIAL TYPICAL BENCH -/ IS’ MINIMUM EASE KEY WIDTH DOWNSLOPE KEY DEPTH PROVIDE SACKDRAIN AS REQUIRED PER RECOM- MENDATIONS OF SOILS LIMIT OF KEY ENGINEER DURINQ GRADINQ EXCAVATION WHERE NATURAL SLOPE GRADIENT IS 6:l OR LESS, BENCHING IS NOT NECESSARY. HOWEVER, FILL IS NOT To SE PLACED ON COMPRESSIBLE OR UNSUIT- ABLE MATERIAL. - FILL SLOPE ABOVE NATURAL GROUND DETAIL JOB NO.: I I 1 I I I 1 I ! I I I I I I I / I REMOVE ALL TOPSOIL. COLLUVIUM AND CREEP MATERIAL FROM TRANSITION CUT/FILL CONTACT SHOWN ON GRADING PLAN CUT/FILL CONTACT SHOWN ON ‘AS-BUILT’ IO’ TYPICAL BEDROCK OR APPROVED FOUNDATION MATERIAL *NOTE: CUT SLOPE PORTION SHALL SE MADE PRIOR TO PLACEMENT OF FILL FILL SLOPE ABOVE CUT SLOPE DETAIL OS NO.: DATE: FIGURE: 05-7928-001-00-00 JUNE 1909 10 GENERAL GRADING RECOMMENDATIONS CUT LOT --ORIQINAL GROUND TOPSOIL. COLLUVIUM AND WEATHERED BEDROCK,/ \OVEREXCAVATE AND /-I .’ UNWEATHERED BEDROCK REGRADE CUT/FILL LOT (TRANSITION) - - - COMPACTED FILL - OVEREXCAVATE AND TOPSOIL. REGRADE WEATHERED I UNWEATHERED BEDROCK BEDROCK R’ 1 , .I' - TRANSITION LOT DETAIL JOB NO.: DATE: FIGURE: - - -- JUNE $989 11, .- ,- ,- .- - - - - BUILDING FINISHED GRADE 5’ OR BELOW DEPTH OF DEEPEST UTILITY TRENCH (WHICHEVER GREATER) TYPICAL WINDROW DETAIL (EDGE VIEW) GRANULAR SOIL FLOODED TO FILL VOIDS \ HORIZONTALLY PLACED COMPACTION FILL PROFILE VIEW ROCK DISPOSAL DETAIL IOE NO.: DATE: FIGURE: - m -- JUNF 1989 12,