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HomeMy WebLinkAboutCT 85-35; Aviara Point; Foundation Investigation; 1992-11-11r r, - n $ rj c r r, r, r r DiC 29 1992 FOUNDATION INVESTIGATION AVIARA POINT, LOTS 278 AND 279,&&%~ CARLSBAD, CALIFORNIA pz 2.4’2.22 pwcz 3W-@p. 7177 A&&E& p41 PREPARED FOR NED AND MARGARET GOOD C/O WIMBERLY, ALLISON, TONG & GGG 2260 UNIVERSITY DRIVE NEWPORT BEACH, CALIFORNIA 92660 PREPARED BY: ICG INCORPORATED 9240 TRADE PLACE, SUITE 100 SAN DIEGO, CALIFORNIA 92121 NOVEMBER 1 I. 1992 JOB NO. 04-9002-001-00-00 LOG NO. Z- 1432 ICG incorporated &Ot~Ch”iC~l: 15 MaSOn ~Wirw, CA 92718 ‘14,951.8686 ax 7141951-7969 Coachella “alley office: ,s,-564 country Club or.. me 400 B ‘aim oesen, CA 92260 619”72-3182 -xxpOrate office: 5 Mason, I, rvirle. CA 92718 714/951-8686 Jax 7141951-7969 Job No. 04-9002-001-00-00 LO8 No.2-1432 November 1 I, 1992 Ned and Margaret Good c/o Wimberly, Allison, Tong & Goo 2260 University Drive Newport Beach, California 92660 Attention: Mr. Charles T. Corwin SUBJECT: FOUNDATION INVESTIGATION Aviara Point, Lots 218 and 279 Carlgbad, California Gentlemen: In accordance with your request, we have completed our foundation investigation for the’ site of the proposed single family residence. Our findings and recommendations are presented herein. In our opinion, the site condition which is most likely to impact the proposed development is the possible presence of scattered areas of uncompacted fill up to 1 foot deep and cemented sandstone. In addition, excavation difficulties may be experienced for footings and utility line excavations. 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, ICG Incorporated Dwight R. Haggard Vice President (Operations) S.D. Region ueotechnical Services, Construction Inspection and Testing TABLE OF CONTENTS INTRODUCTION ................................... 1.1 Purpose ..................................... 1.2 Scope of Services .............................. 1.3 Authorixation ........................... . . . . . PROPOSED DEVELOPMENT ............................... 1. 7 2. 3. 4. FIELD EXPLORATION PROGRAM .......................... 5. r- 6. LABORATORY TESTING PROGRAM .................. . . . SUBSURFACE CONDITIONS ......................... 6.1 General .................................... 6.2 Torrey Sandstone ............................. 6.3 Groundwater ................................ . . . . . . . . . . . . - 7. 8. SITE DESCRIPTION .................................. 3.1 Surface Condition ............................... 3.2 Elevation ..................................... SEISMICITY ...................................... 7.1 General .................................... 1.2 Earthquake Effects ............................ 7.2.1 Surface Fault Rupture .................... 7.2.2 Ground Accelerations .................... 7.2.3 Lurching and Shallow Ground Rupture ....... 7.2.4 Seismically Induced Settlement and Liquefaction 7.2.5 Other Hazards .......................... . . . . . . . . . . . . . . . . . . . . . . . . GEOTECHNICAL EVALUATION AND RECOMMENDATIONS ... 8.1 General ........................................ 8.2 Foundation ...................................... 8.3 Slab-on-Grade ................................... 8.4 Earth Retaining Structures .......................... 8.4.1 Lateral Pressures ............................ 8.4.2 Lateral Resistance ........................... 8.4.3 Unit Weight ............................... 8.4.4 Backdrain and Waterproofing .................. 8.4.5 Backfill ................................... t: Settlement ....................................... 817 Seismicity ....................................... Grading and Earthwork ............................ 8.7.1 General ................................... 8.7.2 Site Preparation ............................. 8.7.3 Excavation Difficulty ........................ 8.7.4 Fill Compaction ............................ 8.7.5 Fill Material ............................... 8.7.6 Site Drainage ............................... 8.7.7 Utility Trenches ............................ 8.8 Temporary Excavations ............................. 8.9 Reactive Soils .................................... 8.10 Geotechnical Observation/Testing ..................... 8.11 Review of Plans .................................. ........... 2 ........... 2 ........... 2 ........... 3 ........... 3 ........... 3 ........... 3 ........... 4 ........... 4 ........... 4 ........... 4 ........... 4 ........... 4 ........... 5 ........... ........... : ........... 5 ........... 5 ........... ........... : ........... 7 ........... 7 ........... 8 ........... 8 ........... 8 ........... ........... ; ........... 9 .......... 10 .......... 10 .......... 10 .......... 11 .......... 11 .......... 11 . , . , . , . , . . 12 .......... 12 .......... 12 .......... 12 .......... 12 .......... 13 .......... 13 .......... .......... :: .......... 15 .......... 15 .......... 16 9. LIMITATIONS OF INVESTIGATION . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . _ . . . . 16 ATTACHMENTS c FIGURES 1 Location Map 2 Site Plan 3 Regional Fault Map 4 Retaining Structures Backdrain Detail-Crushed Rock Alternative 5 Retaining Structures Backdrain Detail-Composite Drain Alternative APPENDICES A References B Laboratory Test Results C Standard Guidelines for Grading Projects TABLE 1 Seismicity of Major Faults 1. INTRODUCTION 1.1 &LRQ$8 FOUNDATION INVESTIGATION AVIARA POINT, LOTS 278 and 279 CARLSBAD, CALIFORNIA a. This report presents the results of our Foundation Investigation performed for the proposed construction of a single family residence at the above referenced location as shown on Figure 1. b. The purpose of this investigation is to provide geotechnical design parameters and recommendations for construction of the subject residence and the associated site preparation. C. For our investigationl we were supplied with a site plan, scale l/4 inch:1 foot, dated July 24, 1992, :prepared by Wimberly, Allison, Tong, and Goo. 1.2 &me of Servicgg Our scope of services for this investigation included the following: a. Review of the referenced geologic maps, aerial photographs, previous geotechnical reports; and other publications pertinent to the subject site. b. Field sampling, which consisted of shallow hand dug test pits, in order to obtain samples for laboratory testing. C. Laboratory testing df selected samples to evaluate the expansion potential, remolded shear, maximum density, and soluble sulfate content. d. Evaluation of groundshaking potential resulting from seismic events occurring on significant faultsin the area. - . - ‘\ ,:?, z ; -’ .,I”1 - ,- I- - - Y I Omo ADAPTED FROM U.S.O.S. 7.5 ENCINITTAS 0UADRANQl.E MAP I LOCATION MAP IOS NO.Z~~-~~~,+,+,,, DATE NWEMBER 1992 ‘. FIOURU 1 SAN DIEa SOILS ENO1NEERVJQ. INC. Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 LO8 No. 2-1432 Page 3 e. Geotechnical engineering analysis of field and laboratory data. f. Preparation of this report presenting our findings, conclusions and reccomendations. 1.3 This investigation was conducted in accordance with the authorization of Mr. Chuck Corwin of Wimberly, Allison, Tong, and Goo. The scope of services performed was consistent with our proposal number SDPl-6020R. dated September 1, 1992. 2. PROPOSED DEVELOPMENT It is understood that the proposed development will consist of a two-story, split level, wood frame structure. The structure will be constructed on grade. Grading consisting of cut/fill to a maximum of 6 feet will be required. Footing loads are expected to be light to moderate. Paved access and an attached garage are planned for the proposed development as well. 3. SITE DESCRIPTION 3.1 The site is located at 7177 Aviara Drive in Carlsbad, California. The site was previously rough graded during mass grading operations for Phase 1 of the Aviara development. The area discussed in this report is designated as Lots 278 and 279, Planning Area 13 or Aviara Point. Lots 278 and 279 are cut lots. Prior to grading, the subject site consisted of a north-south trending ridge. Approximately 30 feet of cut was removed to achieve the existing pad grades. c ,- - r- r - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 4 3.2 Elevation We estimate from the Aviara Phase I grading plan, prepared by P&D Technologies, that the elevation of lot 278 is approximately 215 feet above Mean Sea Level and lot 279 is approximately 222 feet above Mean Sea Level. 4. FIELD EXPLORATION PROCRAM The field investigation was performed on September 22, 1992 and consisted of a site reconnaissance and the excavation of hand dug test pits to retrieve samples for laboratory testing. The locations where the samples were obtained are shown on the Site Plan, Figure 2. 5. LABORATORY TESTING PRGGRAM Selected soil samples considered representative of the subsurface conditions were tested to obtain or derive relevant physical and engineering soil properties. Descriptions of the test methods, and the results are presented in Appendix C. 6. SUBSURFACE CONDITIONS 6.1 &IRBE Lots 278 and 279 are underlain by Torrey Sandstone, an eocene sedimentary bedrock unit. 6.2 Torrev &&QQ~ The Torrey Sandstone, as observed during grading consists of a light brown to light gray, silty, fine to medium grained sandstone (SM), with occasional cross bedding and channel infilling. Cemented sandstone and concretions were encountered during grading of the site. The locally cemented sandstone zones encountered during - - - - .’ .” : SITE PLAN 30 NO.: aa --a- aa* -- -- IDATE: ICInIIPC. -z-tw1-tJu-wJ I NauBMBm 1992 .; . .--..-. 2: rca Incorporot.c Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 5 excavation in Planning Area 13 required heavy ripping and created oversized materials. 6.3 Groundwater Groundwater was not encountered or observed during any of the previous investigations or grading operations. It should be recognised that groundwater levels vary and that excessive irrigation on or adjacent to the project site, or pipeline breaks and/or leaks can cause a fluctuation in local groundwater levels, to develop in the future. In addition, post-construction seepage may develop as a result of excessive irrigation. This conditon will be reviewed and evaluated during the construction phase. 7. SEISMICITY 7.1 General The site can be considered a seismically active area as can all parts of southern California. There are however, no known active faults on or adjacent to the site. Figure 3 shows the known active faults in the region and their geographic relationship to the site. Because of the site’s distance to known active faults, seismic risk is considered low to moderate in comparison to many parts of southern California. 7.2 Earthauake 7.2.1 Surface In our opinion, no credible risk of surface rupture exists at the project site, as no known active faults or potentially active faults cross the site. Cracking related to shaking from distant seismic events is not considered a significant hazard, although ground shaking is a possibility at any site. i I I i /I 4 L. :, / 1 I / I I I I 12 cl 8 1 3 f 8 N 1 8 ,- - ,- r- r- Ned and Margaret Good November 11, 1992 1.2.2 Ground Accelerations Job No. 04-9002-001-00-00 Log No. 2-1432 Page 6 a. In our opinion, based on the information now available, the most significant event likely to affect this project will be an earthquake on the Rose Canyon Fault. Recent work on the Rose Canyon fault zone has indicated that strands within the zone are active. A single trace has been shown to offset topsoil in one location and appears to have created topographic features common in active faulting (offset drainages, pressure ridges, enclosed depressions and fault scarps). The age of the most recent movement, the fault’s recurrence interval (expected period between major earthquake events), and the relationship between the active trace and other faults within the fault zone have not yet been established. b. We have reviewed the existing information available regarding the fault and conclude that for the Rose Canyon Fault, the maximum credible event is a magnitude 7.0 earthquake, based on a 20-mile rupture length (offshore La Jolla to Coronado Bridge). A maximum probable event of magnitude 6.5 is hypothesized for the Rose Canyon Fault. C. For Rose Canyon events, we estimate a peak bedrock acceleration at the site of about 0.448 for a maximum probable earthquake of magnitude 6.5 (Table I). 7.2.3 mina and Shallow Ground Ruoturg Shallow ground rupture should not be a hazard, given the apparent absence of active faults within the site. Ground cracking also should not be a major haxard. However, it is possible that some cracking may occur at any site during a major earthquake. rn~rntn[Ern :Eizsszl . . . . . . 000000 movImoLc) . . . . . . LDo\D\Dlrl-r- trrmmmmm COCOdoIdO ~l-lN0Cll-l . . . . . . 000000 omo(Dmln . . . . . . ~Wl-l-P~ 3 v)SWW ~Ul~rnZZ IduIlntsul ::222: #-I -4 4 -4 4 -4 .;EEEEB lDO11000 ulN(VlnNP Ned and Margaret Good November 1 I, 1992 Job No.04-9002-001-00-00 Log No. 2- 1432 Page 7 7.2.4 &s~g&allv Induced Settlement and Liouefaction Due to the dense condition of the Torrey Sandstone material and to the absence of a shallow groundwater table, seismically induced settlement and liquefaction are not considered hazards at the site. 7.2.5 Other Due to the dense condition of the Torrey Sandstone, the site’s elevation above sea level and distance from any body of water, hazards such as seismically induced slope failures, tsunamis, or seiches are not considered probable. - _- - - - - - - - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 8 8. GEOTECHNICAL EVALUATION AND RECOMMENDATIONS 8.1 General a. Based on the results of our foundation investigation, it is our opinion from a geotechnical viewpoint, that the subject site is suitable for development of the proposed residence provided our geotechnical recommendations presented in this report are implemented in the design and during earthwork construction. b. The site condition which could have the greatest impact to the proposed development is the presence of cemented sandstone and scattered areas of uncompacted fills as deep as 1 foot. Excavations in the cemented sandstone may require special handling. And the uncompacted fill condition can be mitigated following the recommendations contained herein. 8.2 Foundation The followina minimum criteria should be adoft&& a. Allowable Bearing Capacity: qal, = 800D + 300B where: q,,= Allowable Bearing Capacity (lb/f?) b. Minimum Footing Width: C. Minimum Footing Depth: d. Minimum Reinforcement: with a maximum of 3000 lb/f? D = Depth of footing in ft. B - Width of footing in ft. 12 inches 18 inches 2 # 4 bars at both the top and bottom in continuous footings - - Ned and Margaret Good November 11, 1992 - - - - - - - i. ii. . . . 111. iv: a.3 Slab-on-@& Job No. 04-9002-001-00-00 Log No. 2-1432 Page 9 Depth of footing is measured from the lowest adjacent grade. Allowable bearing capacity may be increased by one-third for short-term wind or seismic loads. The footing dimensions recommendations above mentioned should not be considered to preclude more restrictive criteria of regulating agencies or by the structural engineer/architect. The design of the foundation system should be performed by the project structural engineer, incorporating the geotechnical parameters described above. based on anticipated low expansion index for the on-site soils. a. b. The minimum thickness of slab-on-grade should be 4 inches. The minimum steel reinforcement for slab-on-grade should be 6x6- W1.4xW1.4 WWF. C. A modulus of subgrade reaction of 100 Ib/in*/in may be utilized for the slab design. 8.4 Earth Retaininn Structureg 8.4.1 Lateral Pressures a. The following lateral earth pressures are recommended for the design of basement walls and retaining walls with level backfill utilixing on- site materials: Basement Walk 60 Ib/ft*/ft Retaining Walk 40 Ib/ft’lft - - - - - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 10 b. The above mentioned lateral earth pressures were determined based on an assumption that the walls are provided with backdrain system so that no groundwater will be build-up behind the walls. Otherwise, hydrostatic pressures of 62.4 lb/ft*/ft should be taken into account for the lateral earth pressures. C. Additional lateral pressures due to adjacent footings, traffic, etc. should be analyzed separately. 8.4.2 Lateral Resistance a. The lateral earth passive resistance (ultimate) of the on-site materials - 350 Ib/ft*/ft b. The coefficient of friction with on-site materials (concrete-soils) = 0.35 - - C. If both the lateral earth passive resistance and the coefficient of friction are used, the lesser of the two should be reduced by l/2. 8.4.3 unit Weinht The unit weight of on-site soil may be taken as 120 lb/f? . 8.4.4 Backdrain and Wateroroofing a. A backdrain system, connected to a storm drain or other type of outlets should be provided in order to eliminate the potential hydrostatic pressures on the basement/retaining structure. Details of the backdrain are shown on Figures 4 and 5. -. -. - - - - - - - AWAY FROM WALL RETAlNlNa STRUCTURES COMPACTED SACKFIL FILTER FABRIC UIRAFI 140N OR EOUlVALENT LN-PCACE SOIL OR BEDROCK 314’ CRUSNED AQQREQATE 12. MINIMUM ~MINIUUU 3’ OIA. PERFORATED PIPC COMPACTED SO1 IN-PLACE SOL OR BEDROCK NATIVELY USS ‘BROW DITCH) TOP OF WALL DETAIL FOR SLOPING BACKFILL l SUSORAIN SNOULD HAVE A FALL OF AT LEAST 1.5s. l SUSORAIN SHOULD HAVE WEEP HOLES. A FREE GRAVITY OUTFALL OR A 3UMP AN0 PUMP. 0 INSTALLATION OF THE DRAIN SHOULD SE OS8ERVED BY THE SOILS ENQINI=R. l PLACE PIPE {IF USED) WITH PERFORATIONS FACINO DOWNWARD. NOT TO SCALI RETAINING STRUCTURES BACKDRAIN DETAIL-CRUSHED ROCK AL~WWVE 1 OS NO.: OATa 04-9002-001-00-00 NOVEMBER 1992 FIGURE: 4 - _.. - - - ,- - - AWAY FROM WALL RETAININQ STRUCTURES COMPACTED BACKFILL FABRIC FLA MIRADRAIN 6000 OR EQUIVALENT H IN-PLACE SOIL OR BEDROCK -- FASRlC FLAP AROUND PIPE b,lN,UUU 3’ DIA. PERFORATED PIPE ;OYPAGTEO SOK YPERYSASLE CLAY FILL TOP OF WALL DETAIL FOR SLOPING BACKFILL l SUBORAIN SHOULO HAVE A FALL OF AT LEAST 1.6s. 0 ORAINAOE MAT SHOULD SE QLUEO OR NAILED TO WALL. AND SPLICE0 IN ACCORDANCE WITH THE hlANUFACTURER*S RECOYUENOATIONS. l FABRIC SIDE OF DRAIN BOARD SHOULD SE PLACED AWAY FROM WALL. l ~~llOpRuA:; SNOULO HAVE WEEP HOLES. A FREE QRAVITY OUTFALL. OR A SUMP l ~lNSTALLAlION OF THE ORAlN SHOULD 8E OSSERVEO 81 THE SOILS ENOINEER. . PLACE PIPE (IF USED) WITH PERFORATIONS FACING DOWNWARD. IETAINING STRUCTURES SACKDRAIN DETAIL-CDMPDSlTE DRAIN ALTERNATlVE : a8 NO.: OAT&L 04-9002-001-00-00 ’ I FlQUllt: NOVEMBER 1992 5 - - - - - - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 11 b. Waterproofing should be provided to eliminate potential moisture penetration for all the retaining structures. 8.4.5 Backfill a. Backfill should be compacted to achieve a minimum 90% relative compaction based on maximum dry density performed in accordance with ASTM D- 1557. b. Precautions should be taken to ensure that heavy compaction equipment is not used immediately adjacent to the walls. Otherwise, the additional static and dynamic loading may cause the walls to be overstressed and displaced. C. Imported materials, if used for backfilling, should be non-expansive or of low expansivity. Otherwise, additional pressures due to the expansive soils should be evaluated and incorporated into the lateral earth pressures. 8.5 Settlement Total and differential settlements due to the footing loads are expected to be within tolerable limits, 1 inch and l/2 inch respectively over a span of 2Ok ft. These preliminary estimates should be reviewed by the Geotechnical Engineer when foundation plans for the proposed structure are available. 8.6 Seismicity The structure may be designed for seismic forces in accordance with UBC Section 2312, for Zone 4 or per Section 7.2.2, whichever condition is considered more critical. - ,- - Ned and Margaret Good November 11, 1992 a.1 Gradinn and Earthwork 8.7.1 General Job No. 04-9002-001-00-00 Log No. 2-1432 Page 12 a. All earthwork and grading for site development should be accomplished in accordance with the attached Standard Guidelines for Grading Projects (Appendix C), Chapter 70 of the UBC, and requirements of the regulatory agency. b. All special site preparation recommendations presented in the following paragraphs will supersede those in the attached Standard Guidelines for Grading Projects. 8.7.2 Site a. Vegetation, organic soil, and other unsuitable material should be removed from the building area. b. All loose uncompacted fills should be scarified and recompacted prior to any placement of fills. 8.7.3 Excavation Difficulty Special equipment such as jack-hammers may be required to perform excavation due to the nature of the bedrock at near surface that may be cemented. In addition, oversize materials may be produced from excavation of the cemented bedrock. 8.7.4 mnactiog a. All fill and backfill to be placed in association with site development should be accomplished at slightly over optimum moisture conditions. - - Ned and Margaret Good November 11, 1992 - - .- - - Job No. 04-9002-001-00-00 Log No. 2- 1432 Page 13 The minimum relative compaction recommended for fill is 90 percent relative compaction based on maximum dry density performed in accordance with ASTM D-1557. b. Fill should be compacted by mechanical means in uniform horizontal loose lifts not exceeding 8 inches in thickness. 8.7.5 Fill Material a. The on-site soils may be used for compacted fill. However, 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. b. Imported fill materials should be approved by the Geotechnical Engineer prior to importing. Soils exhibiting significant expansion potential (Expansion Index higher than 50) should not be used as import materials. C. Both imported and on-site soils to be used as fill materials should be free of debris, organics (exceeding 3+ %) and cobbles over 6” in maximum dimension. 8.7.6 Site Drainaag a. Foundation and slab performance depends greatly on how well runoff waters drain from the site. This is true both during construction and over the entire life of the structure. - - - - - - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 14 b. The ground surface around structures should be graded so that water flows rapidly away from the structures without pending. The surface gradient needed to achieve this depends on the type of landscaping. C. In general, we recommend that pavement and lawn areas within 5 feet of buildings slope downwards at gradients of at least 2%. d. Densely vegetated areas should have minimum descending gradients of at least 5% within 5 ft of buildings. Densely vegetated areas are considered those in which the planting type and spacing is such that the flow of water is impeded. 8.7.7 Utilitv Trm a. Bedding materials should consist of sand having Sand Equivalent not less than 30, which may then be jetted. b. Existing soils may be utilixed for trench backfill provided they are free of organic materials and rocks over 6 inches in dimension. Compaction should be performed by mechanical means in uniform lifts of 8 to 12 inches. C. The backfill should be uniformly compacted to at least 90% relative compaction based on maximum density performed in accordance with ASTM D-1557. 8.8 Temoorarv Excavath a. Temporary excavations should be sloped back adequately to protect workers and protect against sloughing. It is recommended that excavations deeper that 5 feet be sloped back at a minimum slope ratio of 1.5:l (horizontal to vertical). - - - - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 15 However, it should be noted that surficial failures may still occur due to the nature of the cohesionless soils. b. If steeper slope ratios are necessary, shoring or bracing will be needed to provide a safe and stable working area. We recommend consulting an experienced shoring contractor prior to placement of any shoring devices particularly those methods utilizing vibratory measures of placement. We would, on request, provide geotechnical parameters for the design of such protective works. - - - - - - - - - - - C. The contractor should proceed in such a manner that the safety of workers and adjoining properties is not compromised and work proceeds in accordance with local standards of practice. 8.9 Reactive Soils Soluble sulfate test results are presented in Table B-3. The soluble sulfate tests indicate that the on-site soils should not be detrimental to Type II Portland cement. 8.10 Geotechnical Observation/Testing a. The geotechnical consultant should provide observation and testing services continuously for the following items: i. ii. . . . 111. iv. Placement of backdrain for basement and retaining walls. Backfill for the basement and retaining walls. Backfill of utility trenches. Any placement of fills and their associated removals. - .- - - - - - - - - - - - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 16 b. Excavations for~the basement and other foundations should be observed before placing reinforcing steel. 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 determine that the grading is in general accordance with the recommendations of this report. C. Recommendations provided herein are contingent upon our providing such services during construction. Our personnel should perform sufficient testing of fill during grading to support our professional opinion as to compliance with compaction recommendations. d. All recommendations presented herein are subject to review when excavations are made and subsurface conditions become more fully exposed. 8.11 Review of Plans As foundation and grading plans are completed, they should be forwarded to ICG Incorporated for review and verifying conformance with the intent of these recommendations. 9. LIMITATIONS OF INVESTIGATION a. Our investigation was performed in accordance with the usual and current standards of the profession, as they relate to this and similar localities. No other warranty, expressed or implied, is provided as to the conclusions and professional advice presented in this report. - _- - - - - - - - - - - - - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page 17 b. The samples taken and tested, and the observations performed are considered to be representative of the subject site; however, soil and geologic conditions can vary significantly between sample locations. C. As in most major projects, conditions revealed during construction excavation may be at variance with preliminary findings. If this occurs, the changed conditions must be evaluated by the Project Geotechnical Engineer and Geologist, and revised recommendations be provided as required. d. 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 Architect and Engineer for the project and incorporated into the plans, and that the Contractor and Subcontractors implement such recommendations in the field. e. This firm does not practice or consult in the field of safety engineering. We do not direct the Contractor’s operations, and we c nnot be responsible for other than our own personnel on the site; therefore, the sa fl ty of others is the responsibility of the Contractor. The Contractor should notify the Owner if he considers any of the recommended actions presented herein to be unsafe. f. The findings of this report are considered valid as of the present date. However, changes in the conditions of the site can occur with the passage of time, whether they be due to natural events and processes or to human activities on this or adjacent sites. In addition, changes in applicable or appropriate codes may occur, whether they result from legislation or the broadening of knowledge. g. Accordingly, the findings of this report may be invalid wholly or partially by changes outside our control. Therefore, this report is subject to review and revision as changed conditions are identified. l ** ICG INCORPORATED -- - Ned and Margaret Good November 11, 1992 Dwight R. Haggard, C.E.G. Registration Expires: Vice President (Operations) Patrick Thomas Project Geologist PAT/HW/DRH/ap Job No. 04-9002-001-00-00 Log No. 2-1432 Page 18 Senior Engineer - - - - - Ned and Margaret Good November 11, 1992 APPENDIX A References - - - - - - - Job No. 04-9002-001-00-00 Log No. 2-1432 Page A- 1 - - - - - - - - - - Ned and Margaret Good November 11, 1992 A-l. A-2. A-3. A-4. A-5. A-6. A-7. A-8. A-9. A-10. A-11. Job No. 04-9002-001-00-00 Log No. 2-1432 Page A-Z References Bonilla, M. G. 1970, Surface Faulting and Related Effects, in Wiegel, R. L. (ed.), Earthquake Engineering: Englewood Cliffs, New Jersey, Prentice-Hall, p 47-74. California Division of Mines and Geology, 1975, Recommended Guidelines for Determining the Maximum Credible and the Maximum Probable Earthquakes: California Division of Mines and Geology Notes, Number 43. County of San Diego Env,ironmental Development Agency, 1975, Seismic Safetv Element. San Dieeo Duntv General Plan, County of San Diego. ICG Incorporated, “As-graded Geotechnical Report, Units A through E, Aviara, Carlsbad, California”, dated January 18, 1990, Job No. 04-3179-007-02-10, Log No. O-1094. ICG Incorporated, “As-Graded Geotechnical Report, Lot 292, Planning Area 13, Aviara, Carlsbad, California”, dated May 17, 1990, Job No. 04-3179-007-07-10, Log No. O-1612. Greensfelder, R. W., 1974, Maximum Credible Rock Acceleration from Earthquakes in California: California Division of Mines and Geology Map Sheet 23. Jennings, C. W., 1975, Fault Map of California: California Division of Mines and Geology, California Geologic Data Map Series. Kennedy, M. P., and Peterson, G. L., 1975, Geoloav of San Dieao Metrooolitan Area. California: California Division of Mines and Geology Bulletin 200, 56 p. Lindvall, S. C., Rockwell, T. K., and Lindvall, C. E., The Seismic Hazard of San Dieno Revised: New Evidence for Magnitude 6+ Holocene Earthcmakes on the Rose Canvon Fault Zone: Proceedings of Fourth U.S. National Conference on Earthquake Engineering, May 20-24, 1990, Palm Springs, California, V. 1, p. 679-685. Seed, H. B., and Idriss, I. M., 1982, Ground Motions and So’1 L’auefaction durina Eartm Berkeley, California, Earthquake Engineering Research Inititute, 134~. Wesnousky, S. G., 1986, Earthquakes, Quaternary Faults, and Seismic Hazard in California: Journal of Geophysical Research, v. 91, no. 91, no. B12, p. 12587-12631. - ,- -, Ned and Margaret Good November 11, 1992 - - - 1. Sections B-l to B-6 2. Table B- 1 3. Table B-2 4. Table B-3 5. Figure B-I 6. Figure B-2 APPENDIX B ‘LABORATORY TESTING PROGRAM Laboratory Testing Procedures B-2 Optimum Moisture Content/Maximum Dry Density Test Results Expansion Index Test Result Sulfate Content Test Results Particle Size Test Result Direct Shear Test Results B-3 B-3 Job No. 04-9002-001-00-00 Log No. 2-1432 Page B-l ~,.-- __.~ .-...__- __I ,-. Ned and Margaret Good November 11, 1992 - - - - Job No. 04-9002-001-00-00 Log No. 2-1432 Page B-2 LABORATORY TESTING PRGCEDURES B-l. Classification Soils were classified visually, generally according to the Unified Soil Classification System. Atterberg Limits was attempted to be performed on a representative sample,however, the sample was not able to be rolled. B-2. Q@mm Moisture Content/Maximum Drv Density The maximum dry density/optimum moisture content relationship was determined for representative samples of the on-site materials. The laboratory standard used was ASTM: D 1557. The results are presented in Table B- 1. B-3. Exnansion Index An Expansion Index test was performed on a representative sample of the on-site sandy materials in accordance with UBC 29-2. The test result is shown in Table B-2. B-4. Sulfate Content A soluble sulfate content test was performed on a representative sample of the on-site soils. The laboratory standard used was California 417 (Part I). The test result is presented in Table B-3. B-5. &&le Size Analvsis; Particle size analysis was performed in accordance with ASTM D422. The result is provided~on Figures B- 1. B-6. Direct Shear Direct shear strength tests were performed on representative, remolded samples(90% relative compaction) of the on-site materials. To simulate possible adverse field conditions, the samples were saturated prior to shearing. A saturating device was used which permitted the sample to absorb moisture while preventing volume change. The test results are presented in Figure B-2. The rate of strain of the direct shear testing was 0.05 in/set. .---. -- _~~._~____.~ ~.~~.__ ,., __ - - - - Ned and Margaret Good November 11, 1992 Job No. 04-9002-001-00-00 Log No. 2-1432 Page B-3 TABLE B- 1 QPTIMUM MOISTURE CONTENT/MAXIMUM DRY DENSITY TEST RESULT Test Location Classification TABLE B-2 EXPANSION INDEX TEST RESULT TABLE B-3 SOLUBLESULFATE CONTENT TEST RESULT Test Location I Soil Classification I Soluble Sulfate II PIT # 3 Silty fine sand PIT#4 Silty fine sand >1200 but <1600 ~400 but x800 ..- - - - - - - - - - - PERCENT PA881NC PERCENT PA88lNB I NO.: 04-9002-00GOO-OO 1 PARTICLE SIZE. ANALYSIS RESULTS jF’BUR& ICB Incoroorotc - - - - - - - - - BORINQ E24 CO,“,SiON, ANNE -- ’ ,_ ..- ..33 ciclwr~c ~cdXlPTl0N -r.3 ^ . . . . . c NO. FRICTII 4oDo PIT x 1 I O-l’ I 0 I I .xm I ICUT RRCIWN SILTY FINE SAND LW , I_... _..___._ -.-. . ..~~ -~~~~~ NORMAL LOAD (PBFI Bot%!Q DEPTH (FEET] CO~blW$N. ANQLE OF SAMPLE DESCRIPTION FRICTION,“ 4ooo PIT * 2 I O-l’ I 0 31 GRN SIUY FINE SAND I I I 3000 G: 2 I E : w c” 2000 u) : E ii 5 1000 I/ 00 I( 0 0 2000 2000 3000 3000 4000 4000 6000 6000 6000 6000 ~~ ~~ .--- .--- NORMAL LOAD (PSW SHEARING STRENGTH TEST FK)URB.-. n&a SAN OIEQC SOILS ENOINEE~ - Ned and Margaret Good November 11, 1992 - - - Job No. 04-9002-001-00-00 Log No. 2-1432 Page C- 1 APPENDIX C STANDARD GUIDELINES FOR GRADING PROJECTS _- - - - STANDARD GUIDELINES FOR GRADING PROJECTS 1. 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 SpeCifiCatiCnS; 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. 2. 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 :. 2.13 Page 3 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. 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22 2.23 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 maximuni 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 steepnqss 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 Page a for Grading Projects . . . . - 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, analyze 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 - - .- .c _. 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 conditions 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 Geocechnical 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 sh,puld 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 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. 6.3.2 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. 6.3.3 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. 6.3.4 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 6.3.5 6.3.6 6.3.7 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 retained on the 3/4-inch sieve size. The 12-inch and 40 percent recommendations herein may vary as field conditions dictate. Where rocks or similar irreducible materials of greater than 12 inches but less than four feet of maximum dimension are generated during vading , 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 20-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. 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. 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 - - ,- 6.4 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. 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 KO one foot wide and two feet deep may be backfilled with sand (S-E. > 30), 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 Page 15 r - - -. Standard Guidelines for Grading Projects 6.6.5 6.6.6 7. DRAINAGE 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. 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. 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. 7.1 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. a. SLOPE MAINTENANCE a.1 LANDSCAPE PLANTS In order to decrease erosion surficial slope stabflity 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 he the test party to consult regarding actual types of plants and planting configuration. .; - Standard Guidelines -for Grading Projects 8.2 IRRIGATION - Page 16 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 5188 - -, - 16’ MINIMUM -7 4’ DIAMETER PERFORATED PIPE BACKDRAIN 4. DIAMETER NON-PERFORATED PIPE LATERAL DRAIN SLOPE PER PLAN BENCHINO PROVIDE BACKDRAIN PER BACKDRAIN DETAIL. AN ADDITIONAL BACKDRAIN AT MID-SLOPE WILL SE REQUIRED FOR SLOPE IN EXCESS OF 40 FEET HIQH. KEY-DIMENSIOHSPER SOILS ENQINEER 1 TYPICAL BUTTRESS OR STABILIZATION FILL DETAIL JOB NC.: 04-9002-001-00-00 DATE: NOVEMBER 1992 FIQURE: 1 ~- - - .- NATURAL GROUND - PROPOSED GRADINQ - - COMPACTED FILL SACKDRAIN DETAIL. AN ADDITIONAL SACKDRAIN AT MID-SLOPE WILL SE REQUIRED FOR BACK SLOPES IN EXCESS OF BASE WIDTH ‘W* DETERMINED 40 FEET HIGH. LOCA- BY 5OlL5 ENQINEER TIONS OF BACKDRAINS AN0 OUTLETS PER SOILS ENQINEER ANDIOR EN- QINEERINQ QEOLOGl5T DURING GRADINQ. .- TYPICAL SHEAR KEY DETAIL JO8 NO.: 04-9002-001-00-00 DATE: NOVEMBER 1992 FIGURE: - - - - - OVEREXCAVhTE FINIBH PAD OVEREXCAVAT 3’ AND REPLA WITH COMPACTED 20’ MAXIMUM - SOUND BEDROCK - - -- TYPICAL BENCHINO 2’ MINIMUM OVERBURDEN (CREEP-PRONE) PROVIDE BACKDRAIN PER SACKDRAIN DETAIL. LOCATION OF BACKDRAIN AND OUTLETS PER SOILS ENQINEER AND/OR ENQINEERINQ GEOLOQIBT DURING QRADINQ EOUIPMENT WIDTH (MINIMUM 16’) DAYLIGHT SHEAR KEY DETAIL Iof3 N”~~04-gcux-001-00-O0 DATE: NOVEMBER 1992 FIQURE: 3 BENCHING FILL OVER NATURAL - - - SURFACE OF FIRM EARTH MATERIAL FILL SLOPE 106 MIN. (INCLINED 2% MIN. INTO SLOPE) BENCHING FILL OVER CUT FINI5H FILL SLOPE SURFACE OF FIRM EARTH MATERIAL LlS* MIN. OR 5TASlLITY EOUIVALENT PER SOIL ENQINEERINQ (INCLINED 2x MIN. INTO SLOPE) BENCHING FOR COMPACTED FILL DETAIL JOB NO.: 04-9002-001-00-00 I DATE: NOVEMBER 1992 FIQURE: 4 ‘- __ -- - - -~ - - - .- FINISH SURFACE SLOPE 3 FT3 MINIMUM PER LINEAL FOOT APPROVED FILTER ROCK* COMPACTED FILL 4. MINIMUM DIAMETER 50LI0 OUTLET PIPE SPACED PER SOIL ENQINEER REQUIRE- MENTS OURINQ GRADING 4. MINIMUM APPROVED PERFORATED PIPE** (PERFORATIONS DOWN) MINIMUM 2% QRADIENT TO OUTLET BENCH INCLINED TOWARD DRAIN TYPICAL BENCHINO DETAIL A-A TEMPORARY FILL LEVEL COMPACTED 4. MINIMUM DIAMETER APPROVED SOLID OUTLET PIPE 12. MINIMUM COVER 12. MINIMUM *FILTER ROCK TO MEET FOLLOWINQ 5PECIFICATlONS OR APPROVED EOUAL SIEVE PERCENTAQE PA551Nt **APPROVED PIPE TYPE: 1’ 100 314’ 50-100 SCHEDULE 40 POLYVINYL CHLORIDE 315. 40-100 (P.V.C.) OR APPROVED EOUAL. NO.4 25-40 MINIMUM CRUSH STRENGTH 1000 PSI. NO.30 s-15 NO.60 o-7 NO.200 o-3 TYPICAL BACKDRAIN DETAIL CLP tin. I”.TC. IClnllR=. “” ‘-“-- 04-9002-001-00-00 1 I.., -. NOVEMBER 1992 . .--..-. 5‘ -~- -- - -~ - - - - .- - - - - FINISH SURFACE SLOPE MINIMUM 3 FT3 PER LINEAL FOOT OPEN GRADED AQQREQATE* TAPE AND SEAL AT CONTACT COMPACTED FILL SUPAC 5-P FABRIC OR APPROVED EOUAL 4’ MINIMUM APPROVED PERFORATED PIPE 4” MINIMUM DIAMETER -i,,.,A ~ENsEfy=~~ EENCHINQ TOWARD DRAIN DETAIL A-A r TEMPORARY FILL LEVEL I MINIMUM 12’ COVER COMPACTED BACKFILL MINIMUM 4” DIAMETER SOLID OUTLET PIPE APPROVED *NOTE: AQQREQATE TO MEET FOLLOWING SPECIFICATIONS OR APPROVED EQUAL: SIEVE SIZE PERCENTAGE PA58lNQ 1 112” 100 I’ S-40 314” o-+7 316” o-7 NO. 200 o-3 tm Iv”.: 04-9002-OOl-00-t BACKDRAIN DETAIL (GEOFABRIC) IO DATE: NOVEMBER 1992 FIQURt; fl -- -_- -- - - - - - - - - - CANYON SUBDRAIN DETAILS SURFACE OF FIRM EARTH --7 COMPACTED FILL TYPICAL BENCHING REMOVE UNSUITABLE MATERIAL INCLINE TOWARD DRAIN 5EE DETAILS BELOW TRENCH DETAIL 6’ MINIMUM OVERLAP --mr- OPTIONAL V-DITCH DETAIL MINIMUM 6 FT3 PER LINEAL /FOOT OF APPROVED DRAIN MATERIAL GUPAC 5-P FABRIC SUPAC S-P FABRIC DR APPROVED EQUAL DRAIN MATERIAL SHOULD CONSIST OF MINUS 1.5.. MINUS 1.. OR MINUS .75’~ CRUSHED ROCK MINIMUM 6 FT3 PER LINEAL FOOT MINIMUM OF APPROVED DRAIN MATERIAL ADO MINIMUM 4’ DIAMETER APPROVED PERFORATED PIPE WHEN LARQE FLOW5 ARE ANTICIPATED APPROVED PIPE TO BE SCHEDULE 40 POLY-VINYL- CHLORIDE (P.V.C.1 OR APPROVED EQUAL. MINIMUM CRU5H STRENQTH 1000 psi. GEOFABRIC SUBDRAIN IOB NO.:04-9002-OOI-00-00 DATE: WW~ER 1992 FIQURE: - - - - - - - FINAL GRADE f / f ‘“.‘.“:D%-8’:;::““” , A’ -.. . /. ~/ r,u. / . 4’ / COMPETENT EARTH / MATERIAL TYPICAL BENCH / KEY WIDTH’1 \ HEIQHT DOWNBLOPE KEY DEPTH / LIMIT OF KEY EXCAVATION PROVIDE SACKDRAIN AS REQUIRED PER RECOM- MENOATIONB OF 5OlLS ENQINEER DURING QRAOINQ WHERE NATURAL SLOPE QRAOIENT IS 6:1 OR LESS, BENCHINO IS NOT NECESSARY. HOWEVER, FILL I5 NOT TO BE PLACED ON COMPRESBIBLE OR UNSUIT- ABLE MATERIAL. FILL SLOPE ABOVE NATURAL GROUND DETAIL ‘OB No-: o“-g~2-(KJ1-fJlJ-~ DATE: NOVE~~RER I wi FIQURE: R : L I 2 \ - \ \ ’ : \ \ \ \ 7 _\. 5. :i AL i& IO ml- \u’\ E-1 22 ; ; OW \,y, E >< = 0, g \ 4 ‘\J 5 _, $ 2: -- 0% -I :: Yd i l&lk - LL 13’ & PO OC ,s\ go” iK - --- I!.! 0 lb \O’ 7 c, 5 =\ gz \& KZ 5: 2; ! 3\ i-is . . E 2 ii m&L w 1 - - - ,- GENERAL GRADING RECOMMENDATIONS --ORIQINAL GROUND TOPSOIL. COLLUVIUM AND WEATHERED BEDROCK /. .’ .’ UNWEATHERED BEDROCK REQRADE CUT/FILL LOT (TRANSITION) COMPACTED FILL COMPACTED FILL OVEREXCAVATE ANQ OVEREXCAVATE ANQ REGRADE REGRADE /COLLUVIUM AND /COLLUVIUM AND WEATHERED /’ WEATHERED /’ UNWEATHERED BEDROCK UNWEATHERED BEDROCK BEDROCK /’ BEDROCK /’ ./ ./ A=- A=- TRANSITiON LOT DETAIL Oe No’: 04-9002-001-00-00 DATE: FIQURE: NOVEMBER 1992 1’0: _ I_.._-~., -...-I_ __- .- _~--- - - - - .- - - - BUILDING /- FINISHED QRADE 15’ OR BELOW DEPTH OF OEEPEST UTILITY TRENCH (WHICHEVER GREATER) TYPICAL WINDROW DETAIL (EDGE VIEW) QRANULAR SOIL FLOODED TO FILL VOIDS \ . \ HORIZONTALLY PL ACED / / / / / / / / / / /I / / 7 Y PROFILE VIEW ROCK DISPOSAL DETAIL 10s No-: 04-g002-0()~-(Jo-~ DATE: NOVEMBER 1992 FIGURE: 11.