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HomeMy WebLinkAbout; Proposed Improvements to McGuire Residence; Preliminary Geotechnical Investigation; 2004-03-02CONSTRUCTION TESTING & ENGINEERING, INC. SAN DIEGO, CA 1441 Montiel Road Suite 115 Escondido, CA 92026 (760) 746-4955 (76G) 746-9606 FAX RIVERSIDE, CA 12155 Magnolia Ave. Suite 6C Riverside, CA 92503 (951)352-6701 (951) 352-6705 FAX VENTURA, CA 1645 Pacific Ave. Suite 107 Oxnard. CA 93033 (805) 486-6475 (805) 486-9016 FAX TRACY, CA 242 W. Larch Suite F Tracy, CA 95376 (209) 839-2890 (209) 839-2895 m. SACRAMEnrO, CA 3628 Madison Ave. Suite 22 N. Highlands, CA 95660 (916) 331-6030 (916) 331-6037 WX N. PAIM SPRINGS. CA 19020 N. Indian Ave. Suite 2-K N, Palm Springs, CA 92258 (760) 329-4677 (760) 328-4696- FAX PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED IMPROVEMENTS TO MCGUIRE RESIDENCE 5035 TIERRA DEL ORO STREET CARLSBAD, CALIFORNIA PREPARED FOR: MR. JOHN PYJAR DOMINY + ASSOCIATES ARCHITECTS 2150 WEST WASHINGTON, SUITE 303 SAN DIEGO, CALIFORNIA, 92110 PREPARED BY: CONSTRUCTION TESTING & ENGINEERING, INC. 2414 VINEYARD AVENUE, SUITE G ESCONDIDO, CALIFORNIA 92029 CTE JOBNO. 10-6766 MARCH 2, 2004 GEOTECHNICAL I ENVIRONMENTAL I CONSTRUCTION INSPECTION AND TESTING I CIVIL ENGINEERING I SURVEYING TABLE OF CONTENTS Section Page 1.0 EXECUTIVE SUMMARY 1 2.0 INTRODUCTION AND SCOPE OF SERVICES 2 2.1 Introduction 2 2.2 Scope of Services 2 3.0 BACKGROUND INFORMATION 2 3.1 Site Location and Description 2 3.2 Proposed Improvements 3 4.0 FIELD AND LABORATORY INVESTIGATION 3 4.1 Field Investigations 3 4.2 Laboratory Investigation 4 5.0 GEOLOGY 4 5.1 General Physiographic Setting 4 5.2 Geologic Conditions 4 5.2.1 Fill Soils 5 5.2.2 Quaternary Terrace Deposits 5 5.3 Groundwater Conditions 5 5.4 Geologic Hazards 5 5.4.1 Local and Regional Faulting 6 5.4.2 Site Near Source Factors and Seismic Coefficients 6 5.4.3 Tsunami and Seiche Damage 7 5.4.4 Landsliding or Rocksliding 7 5.4.5 Compressible and Expansive Soils 7 5.4.6 Liquefaction Evaluation 8 5.4.7 Seismic Settlement Evaluation 8 5.4.8 Corrosive Soils 9 5.4.9 Bluff Erosion and Setbacks 9 6.0 CONCLUSIONS AND RECOMMENDATIONS 10 6.1 General 10 6.2 Site Preparation 10 6.2.1 General 10 6.2.2 Site Excavations 11 6.2.3 Fill Placement and Compaction 11 6.2.4 Fill Materials 12 6.3 Temporary Construction Slopes 12 6.4 Foundations and Slab Recommendations 13 6.4.1 General 13 6.4.2 Spread Foundations and Slabs-on-Grade 14 6.4.3 Foundation Settlement 15 6.5 Lateral Resistance and Earth Pressures 15 6.6 Exterior Flatwork 16 6.7 Vehicular Pavements 17 6.8 Drainage 18 6.9 Slopes 18 F:\10-6766\Rpt_Geotecli.doc 6.10 Construction Observation 19 6.11 Plan Review 19 7.0 LIMITATIONS OF INVESTIGATION '-''--'^^^^^^^ 19 FIGURES FIGURE 1 FIGURE 2 INDEX MAP EXPLORATION MAP APPENDICES APPENDIX A APPENDIX B APPENDIX C APPENDIX D REFERENCES CITED EXPLORATION LOGS AND LIQUEFACTION ANALYSIS LABORATORY METHODS AND RESULTS STANDARD SPECIFICATIONS FOR GRADING \\Cte_server\projects\l0-6000 to iO-7000 Projecls\IO-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Page 1 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, Califomia March 2, 2004 CTE Job No. 10-6766 1.0 EXECUTIVE SUMMARY Our investigations were performed to provide site-specific geotechnical information for the construction ofthe proposed improvements to the McGuire Residence on the west side of Tierra Del Oro Street, in Carlsbad, California. The proposed development is considered feasible from a geotechnical viewpoint provided that recommendations in our report are implemented. Based on our observations and reference review, soils beneath the site consist of fill soils overlying Quatemary Terrace Deposits. Due to the different depths at which Quatemary Terrace Deposits are found, there is approximately five feet of fill on the west side of the site and one foot of fill on the east side ofthe site. Groundwater was not encountered at this site during our investigation. During seasonal weather changes, areas of local saturation may be encountered. However, from a review of preliminary project plans, we do not anticipate that groundwater will affect the proposed development, provided appropriate surface drainage is maintained. Based on the geologic findings and referenced review, no active surface faults are known to exist at the site. In general, the results of our review indicate that the proposed project can be constructed as planned provided the recommendations presented in this report are followed. F:\10-6766\Rpt^Geotech.doc Preliminary Geotechnical Investigation Page 2 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 2.0 INTRODUCTION AND SCOPE OF SERVICES 2.1 Introduction Construction Testing and Engineering, Incorporated ("CTE") has prepared this geotechnical engineering report for the proposed improvements to the McGuire Residence. The site is on the west side of Tierra Del Oro Street, in Carlsbad, California. Figure 1 is a map showing the general location of the site. 2.2 Scope of Services Our scope of services included: • Review of readily available geologic reports pertinent to the site and adjacent areas (Appendix A contains a list of cited references). • Explorations to determine subsurface conditions to the depths influenced by the proposed construction. • Laboratory testing of representative soil samples to provide data to evaluate the geotechnical design characteristics of the site foundation soils. • Definition of the general geology and evaluation of potential geologic hazards at the site. • Preparation of this report detailing the investigation performed and providing conclusions and geotechnical engineering recommendations for design and constmction. 3.0 BACKGROUND INFORMATION 3.1 Site Location and Description The site is located on the west side of Tierra Del Oro Street approximately 0.5 mile west of Interstate 5 Freeway. Figure 2 shows the approximate configuration of the site and existing improvements. The site is roughly rectangular in shape and slopes down slightly to the west. The site is situated at an elevation of approximately 30 feet, overlooking the Pacific Ocean to the immediate west. A moderate slope descends approximately 10 feet from the west limits of the building pad to a F:\IO-6766\Rpt_Geotecii.doc Preliminary Geotechnical Investigation Page 3 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, Califomia March 2, 2004 CTE Job No. 10-6766 narrow flat-lying area. An additional moderate slope descends approximately five feet to another flat-lying area with riprap consisting of large boulders and beach and water line beyond. As detailed further herein, the site and immediate vicinity do not appear to be significantly affected by typical bluff erosion. Land use near the site consists of residential properties. The north and south sides of the site are bound by existing residences, the west side by the Pacific Ocean, and the east side by Tierra Del Oro Street. 3.2 Proposed Improvements We understand that the proposed development/project will include the demolition of most or all existing improvements and the subsequent construction of a new single story, wood frame building and associated improvements. Associated improvements may include parking and drive areas, utilities, and landscaping areas. We understand the proposed improvements will be located in the same general area of the existing improvements and will cover the majority ofthe site. 4.0 FIELD AND LABORATORY INVESTIGATION 4.1 Field Investigations Field investigations at this site, performed February 25, 2004, included site reconnaissance and excavation of two soil borings. Soils were logged and visually classified in the field by a geologist using the Unified Soil Classification System. The field descriptions have been modified, where appropriate, to reflect laboratory test results. Excavation logs including descriptions of the soil, in situ field-testing data, and supplementary laboratory data are included F;\l 0-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Page 4 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 in Appendix B. Figure 2 is a map showing the approximate locations of the explorations conducted by this firm. 4.2 Laboratorv Investigation Specific laboratory tests conducted for this investigation included: In-Place Moisture and Density, and 200 Wash. Test method descriptions and laboratory results are presented in Appendix C. 5.0 GEOLOGY 5.1 General Physiographic Setting The site lies within the coastal area of northem San Diego County. Geomorphically, this area is characterized by uplifted marine terraces dissected by intermittent streams. More specifically, the site lies within the Aqua Hedionda Lagoon drainage basin, and is approximately half of a mile south of the lagoon. Topography at the site slopes down slightly from the street to the east toward the ocean to the west. The existing building pad elevation at the site is approximately 36 feet above mean sea level (msl). 5.2 Geologic Conditions Based on mapping compiled by Tan and Kennedy (1996), surface soils near the site consist of Quaternary Terrace Deposits and Tertiary Santiago Formation. Based on our explorations, surface and near surface soils consist of fill soils overlying Quaternary Terrace Deposits. It is anticipated that units of the Tertiary Santiago Formation underlie the Terrace Deposits at depths greater than 20 feet. The soil descriptions below are based on qualitative and quantitative attributes of the soils at the site. F:\10-6766\Rpt_Geotecli,doc Preliminary Geotechnical Investigation Page 5 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE JobNo. 10-6766 5.2.1 Fill Soils Fill soils were encountered to a maximum depth explored of approximately five feet below existing grade. Fill soils appear to be relatively well compacted. These materials were observed to consist primarily of loose to medium dense, moist, medium yellowish brown, compacted silty SAND. Fills will require mitigative grading prior to construction ofthe proposed improvements as recommended herein. 5.2.2 Ouaternary Terrace Deposits Quaternary terrace deposits were observed beneath site fill soils to the maximum depth explored. These materials generally consist of brown, moist, medium dense to very dense, poorly grade or silty medium-grained sands. These native materials are suitable for support of the proposed improvements as recommended herein. 5.3 Groundwater Conditions Groundwater was not encountered during our explorations to the maximum depth of nineteen and a half feet at the site. We anticipate groundwater is located at an approximate elevation of zero feet msl, and may vary with tidal fluctuations. Although groundwater levels may fluctuate, groundwater is not expected to affect the proposed improvements if proper drainage is maintained. 5.4 Geologic Hazards From our investigation it appears that geologic hazards at the site are primarily limited to those caused by violent shaking from earthquake generated ground motion waves. The potential for damage from displacement or fault movement beneath the proposed structures should be F:\10-6766\Rpt_Geotecli.doc Preliminary Geotechnical Investigation Page 6 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 considered low. The site is not within a State of California-designated Alquist-Priolo Special Studies Zone for earthqualce faults. 5.4.1 Local and Regional Faulting Based on our site reconnaissance, evidence from our explorations, and a review of appropriate geologic literature, it is our opinion that the site is not on known active fault traces. According to the California Division of Mines and Geology, a fauh is active if it displays evidence of activity in the last 11,000 years (Hart and Bryant, 1997). The Rose Canyon Fault Zone, approximately five kilometers to the west, is the closest known active fault (Jennings, 1987). Other principal active regional fauhs include: The Coronado Banks, San Jacinto, Palos Verdes, San Andreas, and Elsinore Fauhs. 5.4.2 Site Near Source Factors and Seismic Coefficients In accordance with the 2001 Califomia Building Code, Volume 2, Figure 16-2, the referenced site is located within seismic zone 4 and has a seismic zone factor of Z=0.4. The nearest active fault, the Rose Canyon Fault Zone, is approximately five kilometers to the west and is considered a Type B seismic source. Based on the distance from the site to the Rose Canyon Fault Zone, near source factors of Nv=1.2 and Na=1.0 are appropriate. Based on the shallow subsurface explorations and our knowledge of the area, the site has a soil proflle type of SD and seismic coefficients of Cv^O.77 and Ca-0.44. F:\l 0-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Page 7 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, Califomia March 2, 2004 CTE Job No. 10-6766 5.4.3 Tsunami and Seiche Damage The potential for tsunami damage at the can not be precluded, based on the site's elevation (approximately 30 feet above sea level) and distance from the ocean. However, according to McCullough (1985) the potential for 100 and 500 years tsunami events is four and six feet. This suggests that there is a very low probability of site damage due to the elevation of the building pad of the site (approximately 36 feet above msl). SeismicaUy induced seiche (oscillatory waves) damage is also considered unlikely for the reasons stated above. 5.4.4 Landsliding or Rocksliding According to Tan and Giffen (1995), the site area is generally susceptible to landsliding. However, we did not observe active landslides or rockslides at the site. Landslides have not been mapped near the site area (Tan and Kennedy, 1996). We anticipate that the potential for landsliding or rocksliding to affect the site during its design Ufe is negligible. 5.4.5 Compressible and Expansive SoUs Based on geologic observation and laboratory testing of onsite soils, the fill materials generally exhibit low to moderate compressibility and low expansive characteristics (EI less than 30). Compressible fill materials will be mitigated via overexcavation and recompaction. Underlying native materials are generally non-compressible and non- expansive. Furthermore, native materials do not appear to be subject to significant seismic settlement; therefore, these materials are considered suitable for support of proposed improvements. F:\10-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Page 8 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 5.4.6 Liquefaction Evaluation Liquefaction occurs when saturated fine-grained sands or silts lose their physical strength during earthquake-induced shaking and behave as a liquid. This is due to loss of point- to-point grain contact and transfer of normal stress to the pore water. Liquefaction potential varies with groundwater level, soil type, material gradation, relative density, and the intensity and duration of ground shaking. The potential for damage to the site ft-om liquefaction of site soils is considered low. This is based on the depth to groundwater and the generally medium dense nature of underlying native soils in the area. Appendix B presents the results of our quantitative liquefaction analysis (Civiltech, 2003). 5.4.7 Seismic Settlement Evaluation Seismic settlement occurs when loose to medium dense granular soils densify during seismic events. We anticipate that topsoils and/or loose or soft surficial soils will be mitigated during site grading. The upper 10 to 15 feet of native materials at the site were generally found to be medium dense, but may experience very minor seismic settlement. Based on our evaluation, the building pad area of the site could experience considerably less than 0.5 inches of total settlement as a result of seismic settlement of dry sands. The recommended uniform layer of engineered fill beneath the site and the foundation recommendations herein will adequately mifigate adverse effects of differential settlement of deeper native soils in the unlikely event of a major earthquake in the immediate vicinity of the site. Therefore, in our opinion, the potential for seismic F:\ 10-6766\Rpt_Geotech,doc Preliminary Geotechnical Investigafion Page 9 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE JobNo. 10-6766 settlement resulfing in damage to site improvements should be considered low. Appendix B presents the results of our quantitative liquefaction analysis. 5.4.8 Corrosive SoUs Due to marine environment, onsite soils are anficlpated to be moderately too highly corrosive to both concrete and ferrous metals. CTE does not practice corrosion engineering. Therefore, a corrosion specialist shall be consulted if addifional investigation and/or evaluafion are deemed necessary by the project architect or structural engineer. 5.4.9 Bluff Erosion and Setbacks As previously indicated, due to the low site elevation (approximately 36 feet msl) and the current layback of muhiple moderate slopes, the site is not anticipated to be significantly impacted by the widespread coastal bluff erosion that typically results in relatively fast- paced coastline collapse and/or recession in the northern areas of San Diego County. In addifion, some riprap materials, consisting of large intact boulders, rest along the shoreline ofthe site; these materials provide significant additional ocean wave protecfion to the site, especially during significant storm and/or associated storm-surge. Nevertheless, erosion of all coastal areas and shoreUne retreat is inevitable, especiaUy over extended periods oftime. Based on the information provided above, as well as our understanding of the proposed improvements, it is our opinion that proposed building improvements need not be excessively setback from the exisfing "top of bluff location. However, foundations shall F:\10-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Page 10 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 have adequate setback/embedment as recommended in the subsequent sections of this report. 6.0 CONCLUSIONS AND RECOMMENDATIONS 6.1 General We conclude that the proposed constmction on the site is feasible from a geotechnical standpoint, provided the recommendations in this report are incorporated into the design and constmction of the project. Based on our subsurface investigation and engineering analysis, the proposed improvements can be supported on spread foundations designed and constmcted as recommended herein. However, preparatory site grading will be required. Specific recommendations for the design and construction of improvements at the subject site are included in the subsequent sections of this report. 6.2 Site Preparation 6.2.1 General The site should be cleared of any debris and other deleterious materials. In areas to receive engineered fill, structures or distress-sensitive improvements, expansive, surficial eroded, desiccated, burrowed, or otherwise loose or disturbed soils should be removed to the depth of competent nafive material and to a minimum depth of five feet below existing or proposed building pad elevations, whichever is deeper. Based on our onshe explorations, we anticipate uniform removals of five feet below existing grades will generally be adequate. However, localized areas of deeper removals may be required. In F:\! 0-6766\Rpl_Geotech,doc Preliminary Geotechnical Investigation Page 11 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 addition, any materials disturbed during demolition of existing site improvements shall be completely removed and replaced as engineered fill. Organic and other deleterious materials not suitable for structural backfill should be disposed of offsite at a legal disposal site. Prior to placing any engineered fill, exposed subgrade shall be scarified, moisture condifioned to near optimum moisture content, and properly recompacted. General engineered fill shall be compacted to a minimum 90% relative compaction (per ASTM D 1557) at the near optimum moisture contents. 6.2.2 Site Excavations Site excavations can generally be accomplished using heavy-duty construcfion equipment. Design recommendations for temporary construction slopes are provided in a subsequent section of this report. Site excavations should be observed by CTE. Such observations are essential to identify field conditions that differ from those identified during our subsurface investigation and to adjust designs to actual field conditions encountered. 6.2.3 Fill Placement and Compaction As stated, an engineer or geologist from CTE should be called upon to verify that the proper site preparation has occurred before fill placement begins. As stated, following the recommended removals, areas to receive fills or improvements should be scarified, moisture conditioned near optimum moisture content, and properly recompacted. F;\l 0-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Page 12 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, Califomia March 2, 2004 CTE Job No. 10-6766 General fill and backfill should be compacted to a minimum relative compaction of 90% as evaluated by ASTM D-1557 (except in pavement areas) at moisture contents near optimum (generally within two percent). The optimum lift thickness for backfill soil will be dependent on the type of compaction equipment used. Generally, backfill should be placed in uniform lifts not exceeding eight inches in loose thickness. If proposed, sloping backflll shall be properly keyed and benched. Backfill placement and compaction should be done in overall conformance with geotechnical recommendations and local ordinances. AU grading shall be performed in accordance with the regulations of the governing authorities. 6.2.4 Fin Materials Soils derived from on-site materials are considered suitable for reuse on the site as fill, provided they are screened of significant organic materials and materials greater than three inches in maximum dimension, if encountered. Imported fill beneath structures, pavements and walks should have an expansion index less than or equal to 30 (per UBC 18-I-B) with less than 35% passing the no. 200 sieve. Imported fill soils for use in stmctural or slope areas should be evaluated by the soils engineer to determine strength characteristics before placement on the site. 6.3 Temporary Construction Slopes Sloping recommendations for unshored temporary excavations are provided herein. The recommended slopes should be relatively stable against deep-seated failure, but may experience localized sloughing. Recommended slope ratios are set forth in Table 1. F:\10-6766\Rpl_Geotecli.doc Preliminary Geotechnical Investigation Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 Page 13 CTE JobNo. 10-6766 TABLE 1 RECOMMENDED TEMPORARY SLOPE RATIOS SOILS TYPE SLOPE RATIO (Horizontal: Vertical) MAXIMUM HEIGHT B {Quaternary Terrace Deposits) 1:1 (MAXIMUM) 8 FEET Actual field conditions and soil type designations must be verified by a "competent person" while excavations exist according to Cal-OSHA regulations. In addition, the above sloping recommendations do not allow for potential water seepage, or surcharge loading at the top of slopes by vehicular traffic, equipment or materials. Appropriate surcharge setbacks must be maintained from the top of all unshored slopes. Excavations shall not encroach within a 1:1 plane extended down from adjacent structures to remain. 6.4 Foundations and Slab Recommendations 6.4.1 General The foUowing recommendations are for preliminary planning purposes only. These foundation recommendations should be reviewed after completion of earthwork and tesfing of surface soils. We anticipate all foundations for proposed stmctures will be founded entirely in properly compacted engineered fill materials. Foundations should not straddle transitional conditions (changes from cut to fill soils). F:\10-6766\Rpt_Geolech.doc Preliminary Geotechnical Investigation Page 14 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 6.4.2 Spread Foundations and Slabs-on-Grade Continuous and isolated spread footings are suitable for use at this site. We anticipate that all building footings will be founded enfirely in properly compacted fills as recommended herein. Foundation dimensions and reinforcement should be based on allowable bearing values of 2,500 pounds per square foot (psf) for footings embedded a minimum of 18 inches in properly recompacted fill materials. The allowable bearing value may be increased by one third for short durafion loading which includes the effects of wind or seismic forces. Minimum footing reinforcement for continuous footings should consist of four No. 4 reinforcing bars; two placed near the top and two placed near the bottom or as per the project structural engineer. The structural engineer should design isolated footing reinforcement. It is recommended that isolated footings be connected to each other or adjacent continuous foundations via minimum 12-inch by 12-inch tie beams with mimmum reinforcing steel percentages. As a precautionary measure, it is generally recommended that all foundations attain a minimum 15-foot horizontal distance to daylight. Deepening of locally affected foundations may be a suitable means of attaining the prescribed foundation setbacks. Lightly loaded concrete slabs shouid be a minimum of five inches thick. Minimum slab remforcement should consist of #4 reinforcing bars placed on 24-inch centers, each way, at mid-slab height. Moisture sensitive floor areas shall be underlain by a mimmum 10- F.\10-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Page 15 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 mil visqueen layer, with all laps sealed or taped. Slabs subjected to heavier loads may require thicker slab sections and/or increased reinforcement. 6.4.3 Foundation Settlement Based on the preliminary plans as well as the conditions observed at the site, the maximum total static setfiement is expected to be less than 1.0 inches and the maximum differential static settlement is expected to be less than 0.5 inches. Total and differential dynamic settlements are anticipated to be less than 0.5 inches, and will not likely affect the proposed improvements. 6.5 Lateral Resistance and Earth Pressures Foundations placed in firm, well-compacted fill material may be designed using a coefficient of friction of 0.35 (total frictional resistance equals the coefficient of friction times the dead load). A design passive resistance value of 250 pounds per square foot per foot of depth (with a maximum value of 1,000 pounds per square foot) may be used. The allowable lateral resistance can be taken as the sum of the frictional resistance and the passive resistance, provided the passive resistance does not exceed two-thirds ofthe total allowable resistance. Walls below grade up to ten feet high and backfilled using granular soils may be designed using the equivalent fluid weights given in Table 2 below. If segmental block walls are proposed at the site, our office shall be contacted and additional design and construction recommendations will be provided upon request. F:\10-6766\Rpl_Geotech.doc Preliminary Geotechnical Investigation Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 Page 16 CTE Job No. 10-6766 TABLE 2 EQUIVALENT FLUID UNIT WEIGHTS (pounds per cubic foot) WALL TYPE LEVEL BACKFILL SLOPE BACKFILL 2:1 (HORIZONTAL: VERTICAL) CANTILEVER WALL (YIELDING) 35 55 RESTRAINED WALL 55 85 The above values assume non-expansive backfill and free draining condifions. Measures should be taken to prevent a moisture buildup behind all walls below grade. Drainage measures should include free draining backfill materials and perforated drains. Drains should discharge to an appropriate offsite location. We recommend that walls below grade be backfiUed with soils having an expansion index of 20 or less. The backfill area should include the zone defmed by a 1:1 sloping plane, extended back from the base of the wall. Wall backfill should be compacted to at least 90 percent relative compaction, based on ASTM D1557-9L BackfiU should not be placed untU walls have achieved adequate structural strength. Heavy compactors, which could cause distress to walls, should not be used. 6.6 Exterior Flatwork To reduce the potential for distress to exterior flatwork caused by minor settlement of foundation soils, we recommend that such flatwork be reinforced and installed with crack-control joints at appropriate spacing as designed by the project architect. The upper 12 inches of subgrade should be properly recompacted before placing concrete. Flatwork shall be a minimum four inches F:\] 0-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 Page 17 CTE JobNo. 10-6766 thick. We recommend flatwork be reinforced with minimum #3 rebar spaced at 18 inches, on center, both ways. Reinforcing shall be located near mid-height of the concrete section. 6.7 Vehicular Pavements The proposed development may include the construction of pavement areas. Presented in Table 3 below are recommended pavement sections. Two options are presented. Option 1 is for construction of asphalted concrete pavements; Opfion 2 is for construcfion of full-depth concrete pavements. The pavement secfions presented are based on estimated traffic indices and the design value for the Resistance "R"- Value of onsite materials. The upper 12 inches of subgrade and all base materials shall be compacted to 95% of laboratory determined maximum dry density, as per ASTM D1557, at moisture contents near optimum. PRELIMIN TABLE 3 ARY RECOMMENDED PAVEMENT THICKNESS Traffic Area Assumed Traffic Index Preliminary Subgrade "R"-Value Option 1: Asphalt Pavements Option 2: Full Depth Concrete Pavements (inches) Traffic Area Assumed Traffic Index Preliminary Subgrade "R"-Value AC Thickness (inches) Class il Aggregate Base Thickness (inches) Option 2: Full Depth Concrete Pavements (inches) Drive and Parking Areas 4.5 25 2.5 or 4.0 4,0 or 0,0 5.5 At the owner's option, upon completion of preparatory grading in the proposed pavement areas, additional subgrade sampling and testing for "R" Value determination can be conducted. This F:\10-6766\Rpt_Geotech.doc Preliminary Geotechnical Investigation Page 18 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, CaUfornia March 2, 2004 CTE Job No. 10-6766 additional testing will enable us to modify the pavement sections based on the as-graded conditions, if necessary. 6.8 Drainage Surface runoff should be collected and directed away from improvements by means of appropriate erosion reducing devices and positive drainage should be established around the proposed improvements. Positive drainage should be directed away from improvements at a gradient of at least two percent for a distance of at least five feet. Surficial contours within the area should keep water from affecfing the foundations provided planter areas are not over watered. The project civil engineer should evaluate the on-site drainage and make necessary provisions to keep surface water from affecting the site. 6.9 Slopes Slopes should be constructed at 2:1 (horizontal: vertical) or flatter. Although graded slopes on this site will be grossly stable (i.e., factor of safety greater than 1.5), the soils will be somewhat erodible. Therefore, mnoff water should not be permitted to drain over the edges of slopes unless that water is confined to properly designed and constmcted drainage facilities. Erosion resistant vegetation should be maintained on the face of all slopes. As previously stated, all slopes shall be properly keyed and benched. Typically, soils along the top porfion of a fill slope face will tend to creep laterally. We do not recommend that distress sensitive landscape improvements be constructed within five feet of siope crests in fill areas. F:\10-6766\Rpl_Geotech,doc Preliminary Geotechnical Investigafion Page 19 Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, California March 2, 2004 CTE Job No. 10-6766 6.10 Construcfion Observation The recommendafions provided in this report are based on preliminary design information for the proposed construcfion and the subsurface conditions found in the exploratory boring locations. The interpolated subsurface conditions should be checked in the field during construction to verify that conditions are as anticipated. Recommendations provided in this report are based on the understanding and assumption that CTE will provide the observafion and tesfing services for the project. All earthwork should be observed and tested to verify that grading activity has been performed according to the recommendations contained within this report. All foundation excavations shall be evaluated by the project engineer before reinforcing steel placement. 6.11 Plan Review CTE should review all project grading and foundation plans before the start of earthworks to identify potential conflicts with the recommendations contained in this report. 7.0 LIMITATIONS OF INVESTIGATION The recommendations provided in this report are based on the anticipated construction and the subsurface conditions found in our explorations. The interpolated subsurface conditions should be checked in the field during construction to verify that conditions are as anficlpated. Recommendations provided in this report are based on the understanding and assumption that CTE will provide the observation and tesfing services for the project. All earthworks should be observed and tested to verify that grading acfivity has been performed according to the F:\l 0-6766\Rpt_Geotech,doc Preliminary Geotechnical Investigation Proposed Improvements to McGuire Residence 5035 Tierra Del Oro Street, Carlsbad, CaUfornia March 2, 2004 Page 20 CTE JobNo. 10-6766 recommendations contained within this report. The project engineer should evaluate all foofing trenches before reinforcing steel placement. The field evaluafion, laboratory testing and geotechnical analysis presented in this report have been conducted according to current engineering pracfice and the standard of care exercised by reputable geotechnical consultants performing similar tasks in this area. No other warranty, expressed or implied, is made regarding the conclusions, recommendations and opinions expressed in this report. Variations may exist and conditions not observed or described in this report may be encountered during construction. Our conclusions and recommendations are based on an analysis of the observed condifions. If conditions different from those described in this report are encountered, our office should be notified and additional recommendafions, if required, will be provided upon request. We appreciate this opportunity to be of service on this project. If you have any quesfions regarding this report, please do not hesitate to contact the undersigned. Respectfully submitted, CONSTRUCTION TESTUIG & ENGINEERING, ]NC. Dan T. Math, RCE #61013 Senior Engineer J^F.^nch, CEG #1890 Senior Geologist F:\lO-6766\Rpt_Geotech.doc HT^Zl.OOff W TC»>01 map prtited on 03/fm/04 from "CaWbn^.tpo" and "Untitled, tpg" 117»Z0.000* W 117"19.000' W WGSe4 117»18,000' W WGSa4 117-18.000' W Pmtti fton TOPOl 02000 ^radflMniPniteliaw (mnr topcccm} % CONSTRUCTION TESTING & ENGINEERING, INC. BWMBKDNUNC. GEOIBCMNICAL AND CONSTRUCTION ENGMEBUNG TESTING AM) MSPBCIION 2414 VINEYARD AVENUE. STEO ESCOMMDOCA. 92029(760)746-4«65 SITE INDl^ MAP— Proposed McGuire's ResideiK^ 5035 Tieira Del Oixi Street Carlsbad, Califomia vtnssm 10-6766 *^ AS SHOWN 1 T .-•• ...I ••- ?Q a z LU o LU K: Q \~ < o o _j o z cn o QQ HI I-< 1 Q. < CO CO > I 1 Big II SO CJ APPENDIX A REFERENCES CITED F:\I0-6766\PRELIMINARY GEOTECHNICAL iiiveslmatioii doc REFERENCES CITED 1. Hart, Earl W. and Bryant, W.A., 1997, "Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake FauU Zoning Act with Index to Earthquake Fault Zones Maps," California Division of Mines and Geology, Special Publicafion 42. 2. Jennings, C. W., 1987, "FauU Map of Califomia with Locations of Volcanoes, Thermal Springs and Thermal Wells." 3. Tan, S. S., and Giffen, D.G., 1995, "Landslide Hazards in the Northem Part of the San Diego Metropolitan Area, San Diego County, Califomia; Landslide Hazard Identification Map", California Department of Conservation, Division of Mines and Geology, Open- File Report 95-04, State of Califomia, Division of Mines and Geology, Sacramento, California. 4. LiquifyPro, Version 4, Civiltech Corporafion, 2003, "Computer Program for Evaluation of Liquefacfion Potential and Calculations of Settlement of Soil Deposits Due to Seismic Loads per NCEER Workshop and SP 117 Implementafion." 5. McCulloch, D.S., 1985, "Evaluating Tsunami Potential" in Ziony, J.L, ed., Evaluafion Earthquake Hazards in Los Angeles Region - An Earth-Science Perspective, U.S. Geological Survey Professional Paper 1360 6. Tan, S. S., and Kennedy M., 1996, "Geological Map of the Oceanside and San Marcos 7.5' Quadrangles", Geological Maps of the Northwestern Part of San Diego County, California, Califomia Department of Conservation, Division of Mines and Geology. 7. Uniform Building Code, 1997, Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada. FAI 0-6766\Rpt_Geotech.doc APPENDIX B EXPLORATION LOGS AND LIQUEFACTION ANALYSIS F.\10-6766\Rpt_Geotech.doc CONSTRUCTION TESTING & ENGINEERING, INC. GEOTECHNICAI, AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION 24M VINEYARD AVENUE SUITE G ESCONDIDO CA 9I02'>(7(iO)74f>-495i ENGINEEKISC INC DEFINITION OF TERMS PRIMARY DIVISIONS SYMBOLS SECONDARY DIVISIONS O O O < 'Z < Z § d GRAVELS MORE THAN HALF OF COARSE FRACTION IS LARGER THAN NO. 4 SIEVE SANDS MORE THAN HALF OF COARSE FRACTION IS SMALLER THAN NO. 4 SIEVE CLEAN GRAVELS < 5% FINES WELL GRADED GRAVELS, GRAVEL-SAND MIXTURES LITTLE ORNO FINES GRAVELS WITH FINES POORLY GRADED GRAVELS OR GRAVEL SAND MIXTURES, LITTLE OF NO FINES GM GC SILTY GRAVELS, GRAVEL-SAND-SILT MIXTURES, NON-PLASTIC FINES CLAYEY GRAVELS, GRAVEL-SAND-CLAY MIXTURES, PLASTIC FINES CLEAN SANDS < 5% FINES SW WELL GRADED SANDS, GRAVELLY SANDS, LITTLE OR NO FINES SP POORLY GRADED SANDS, GRAVELLY SANDS, LITTLE OR NO FINES SANDS WITH FINES TTTT SM SlLTY SANDS, SAND-SILT MIXTURES, NON-PLASTIC FINES CLAYEY SANDS, SAND-CLAY MIXTURES, PLASTIC FINES tA: n. N O -• il 7- o SILTS AND CLAYS LIQUID LIMIT IS LESS THAN 50 SILTS AND CLAYS LIQUID LIMIT IS GREATER THAN 50 MH •yyyyXy' CH ' OH INORGANIC SILTS, VERY FINE SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS, SLIGHTLY PLASTIC CLAYEY SILTS INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY, SANDY. SILTS OR LEAN CLAYS ORGANIC SILTS AND ORGANIC CLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SANDY OR SILTY SOILS, ELASTIC SILTS INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTY CLAYS HIGHLV ORG.ANIC SOILS PT PEAT AND OTHER HIGHLY ORGANIC SOILS GRAIN SIZES BOULDERS COBBLES GRAVEL COARSE FINE SAND COARSE MEDIUM FINE SILTS AND CLAYS 12' 10 40 200 CLEAR SQUARE SIEVE OPENING U.S. STANDARD SIEVE SIZE ADDITIONAL TESTS (OTHER THAN TEST PIT AND BORING LOG COLUMN HEADINGS) MAX- Maximum Dry Densily GS- Grain Size Distribution SE- Sand Equivalent El- Expansion Index CHM- Sulfate and Chloride Content, pH, Resistivity COR - Corrosivity PM- Permeability SG- Specific Gravity HA- Hydrometer Analysis AL- Atterberg Limits RV-R-Value CN- Consolidation PP- Pocket Penetrometer WA- Wash Analysis DS- Direct Shear UC- Unconfined Compression MD- Moisture/Density M- Moisture SC- Swell Compression 01- Organic Impurities FIGURE: BLl PRECONSTRUCTION TESTING & ENGINEERING, INC GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION 2411 VINIIYAKD AVENUE. SUITE G ESCONDIDO CA 9102 9 (7 60) 746 .4955 ENCiM-"Ei;jKG,rsi; PRO.iKCT: CTF JOB NO: I-( KiCiFDBV: DRILLER: DRILL METHOD: SAMPLE METHOD: SHEET: DRILLING DATE: ELEVATION: of BORING LEGEND DESCRIPTION Laboratory Tests -ICh -2fh -25- Block or Clumk Sample Bulk Sample "SM Standard Penetration Test Modified Split-Barrel Drive Sampler (Cal Sampler) Thin Walled Army Corp. ofEngineers Sample Groundwater Table Soil Tvpe or Classification Change •) — Formation Change KApproximate boundaries queried (?)1 Quotes are placed around classifications where the soils e.^;isl in situ as bedrock FIGURE: | BL2 #T%C0NSTRUCT10N TESTING & ENGINEERING, INC, GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION 24 14 VINEYARD AVENUE. SUITE C ESCONDIDO CA '>2t)2'> (7f,[() 74(i.4'J55 ESOINEEEUKCINC PROJECT: CTH ,IOB NO. LOGGED BY: MCGUIRE RESIDENCE 10-6766 D, RIES DRILLER; DRILL METHOD: SAMPLE METHOD: PACIFIC DRILUNG TRIPOD RIG BULK, CAL RINGS, SPT SHEET: I DRILLING DATE. ELEVATION: of 1 2/35/2004 o BORING: B-l DESCRIPTION Laboratory Tests -0- -5- SM 0-0.2' Grass/Turf 0.2'-@ 5.0'Fill Medium yeUowish brown, loose to medium dense, moist, silty SAND (SM) 10 12 15 105.7 6,9 SM @ 5' Quaternarv Tenrace Deposits: Medium brown, medium dense slightly moist, SAND with SILT (SM), fine to medium gramed. MD @ 7' becomes SAND (SP) -IO-IO SP Light yellowish, rusty orange brown, and dark gray to black layers, medium dense, slightly moist, fine to medium SAND (SP), trace SILT WA ^5- 20 30 30 SP SP Light yellowish, rusty orange brown, and dark gray to black layers, very dense, slightly moist, fine to medium SAND (SP), trace SILT Light yellowish, rusty orange brown, and dark gray to black layers, very dense, slightly moist, fine to medium SAND (SP), trace SILT, dense WA ^0-Total depth 19.5' No Groundwater Hole Backfilled -25- Boring B-l ^CONSTRUCTION TESTING & ENGINEERING, INC. GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION 2414 VINEYARD AVENUE. SUITE C ESCONDIDO CA 'J2(P2') n<<») 74 (i- 4'13 5 ENCINEEIUKGJNC PROJECT CTE JOB NO: LOGGED BY: MCGUIRE RESIDENCE 10-6766 D RIES DRILLER: DRILL METHOD: SAMPLE METHOD: PACIFIC DRILLING TRIPOD RIG BULK, CAL RINGS, SPT SHEET: I of I DRILLING DATE: 2/23/2004 ELEVATION: BORING: B-2 DESCRIPTION Laboratory Tests -0- -5- HO- 10 12 2 30 30/4" SM SM O-i' Fili/Topsoii: Dark brown, loose, moist, silty, SAND (SM) with organics. @ 1' Quaternarv Terrace /deposits: Brown medium dense, moist, silty SAND (SM). WA Brown medium dense, moist, less silt SAND (SM). SM Brown medium dense, moist, less silt SAND (SM). SP Yellowish brown, medium dense, slightly moist, SAND (SP) fine to medium grained. Yellowish brown, very dense, slightly moist, SAND (SP) fine to medium grained. WA ^0- -25- Total depth 19.5' No Groundwater Hole Backfilled LIQUEFACTION ANALYSIS MCGUIRE RESIDENCE HoleNo.=B-1 Water Depth=36 ft Surface Elev.=~36 Shear Stress Ratio (ft) 0 0 Factor of Safety Settlement 10 1 5 0(in.) Raw Unit Fines 1 SPTV\/eight % 10 20 30 40 fs=1 50 CRR CSR Shaded Zone has Liquefaction Potential 17 115 5 16 115 4.3 25 115 5 60 115 5 Wet— Dry- S = 0.06 in. 50 115 5 •Si & o ^ 'd< > 0< O O •<Si > On C; O 0 O o > do O O o Ci< o O > Oo C> O <::i( c 0.; C> o q do Magnitude=6.9 A cceferation=. 30g So(7 Descnption 60 70 CiviiTech Corporation Boring B-1 Plate B-1 LIQUEFACTION ANALYSIS MCGUIRE RESIDENCE Hole No. =S-2 Water Depth=35 ft Surface Elev.=-35 Shear Stress Ratio Factor of Safety Settlement 10 1 5 0(in.) 1 llllllllll I I I I I I I M 10 20 30 40 50 , fs=1 CRR— CSR Shaded Zone has Liquefaction Potential Raw Unit Fines SPT Weight % 12 115 15 19 115 3.8 22 115 5 60 115 5 Wet— Dry- S = 0.06 in. 50 115 5 ) Oo O O <:a| 'J< C> O O > Oo O =;•: > Oo O O > Oo O O fJl •Ss O o Oo o o ^ > 0 O c^ o Oo • o. O C3| > 0 o OP O Q ) Oo O >::: J Oo O" O <;: O ' 0< O O Cil ) Oo o> ) Go Magnitude=6.9 Acceleration=. 30g Soil Description 60 70 CiviiTech ODrporation Boring B-2 Plate B-2 APPENDIX C LABORATORY METHODS AND RESULTS F:\I0-6766\PRELIMINARY GEOTECHNICAL invesliaalion.doc APPENDIX C LABORATORY METHODS AND RESULTS Laboratory tests were performed on representative soil samples to detect their relative engineering properties. Tests were performed following test methods of the American Society for Testing Materials or other accepted standards. The following presents a brief description of the various test methods used. Laboratory results are presented in the following section of this Appendix. Classification Soils were classified visually according to the Unified Soil Classification System. Visual classifications were supplemented by laboratory testing of selected samples according to ASTM D2487. Particle-Size Analysis Particle-size analyses were performed on selected representative samples according to ASTM D422. F:\I0-6766\PREL1MINARY GEOTECHNiCAL invesUsalion.de ,*>CONSTRUCTION TESTING & ENGINEERING, INC. GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING .\ND INSPECTION 2J\A VINEVAREl AVENUE. SUITE G F, SCONDIDO CA •>2in.'l (7l>(Ji 7J(.-4')i5 ENGINEE RINO .INC 200 WASH ANALYSIS LOCATION DEPTH (feet) MATERIAL PASSING 200 SIEVE (%) CLASSIFICATION B-l 10.0 4.3 SP B-l 19.0 5,0 SP B-2 3.5 19.4 SM B-2 15.0 3.8 SP IN-PLACE MOISTURE AND DENSITY LOCATION DEPTH MOISTURE DRY DENSITY (feet) (%) B-l 5.0 6.9 105.7 LABORATORY SUMMARY CTE JOBNO. 10-6766 APPENDIX D STANDARD SPECIFICATIONS FOR GRADING F:\10-6766\PRELIMINARY GEOTECHNICAL investmation.doc Appendix D Page D-l Standard Grading Specifications Section 1 - General The guidelines contained herein represent Construction Testing & Engineering's standard recommendations for grading and other associated operations on construction projects. These guidelines should be considered a portion of the project specifications. Recommendations contained in the body of the previously presented soils report shall supersede the recommendations and or requirements as specified herein. The project geotechnical consultant shall interpret disputes arising out of interpretation of the recommendations contained in the soils report or specifications contained herein. Section 2 - Responsibilities ofProject Personnel The geotechnical consultant should provide observation and testing services sufficient to assure that geotechnical construction is performed in general conformance with project specifications and standard grading practices. The geotechnical consultant should report any deviations to the client or his authorized representative. The Client should be chiefly responsible for all aspects of the project. He or his authorized representative has the responsibility of reviewing the findings and recommendations of the geotechnical consultant. He shall authorize or cause to have authorized the Contractor and/or other consultants to perform work and/or provide services. During grading the Client or his authorized representative should remain on-site or should remain reasonably accessible to all concerned parties in order to make decisions necessary to maintain the flow of the project. The Contractor should be responsible for the safety of the project and satisfactory completion of all grading and other associated operations on construction projects, including, but not limited to, earth work in accordance with the project plans, specifications and controlling agency requirements. Section 3 - Preconstruction Meeting A preconstruction site meeting shall be arranged by the owner and/or client and shall include the grading contractor, the design engineer, the geotechnical consultant, owner's representative and representatives ofthe appropriate governing authorities. Section 4 - Site Preparation The client or contractor should obtain the required approvals from the controlling authorities for the project prior, during and/or after demolition, site preparation and removals, etc. The appropriate approvals should be obtained prior to proceeding with grading operations. Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods, stumps, trees, root of 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. Demolition should include removal of buildings, structures, 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 from the areas to be graded. Demolition of utilities should include proper capping and/or rerouting pipelines 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. F:\l 0-6766\PRELIMINARV GEOTECHNICAL investieation.doc Appendix D Page D-2 Standard Grading Specifications — Trees, plants or man-made improvements not planned to be removed or demolished should be protected by the contractor from damage or injury. 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. Section 5 - Site Protection Protection of the site during the period of grading should be the responsibility of the contractor. Unless other provisions are made in writing and agreed upon among the concerned parties, completion of a portion of the project should not be considered to preclude that portion or adjacent areas from the requirements for site protection until such time as the entire project is complete as identified by the geotechnical consultant, the client and 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. Where low areas cannot be avoided, pumps should be kept on hand to continually remove water during periods of rainfall. Rain related damage should be considered to include, but may not be limited to, erosion, silting, saturation, swelling, structural distress and other adverse conditions as determined by the geotechnical 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. 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 ofthe completed project and, therefore, should not be considered to preclude the responsibilities of the contractor. Recommendations by the geotechmcal consultant should not be considered to preclude requirements that are more restrictive by the regulating agencies. The contractor should provide during periods of extensive rainfall plastic sheeting to prevent unprotected slopes from becoming saturated and unstable. When deemed appropriate by the geotechnical consultant or governing agencies the contractor shall install checkdams, desilting basins, sand bags or other drainage control measures. In relatively level areas and/or slope areas, where saturated soil and/or erosion gullies exist to depths of greater than LO foot; they should be overexcavated and replaced as compacted fill in accordance with the applicable specifications. Where affected materials exist to depths of 1.0 foot or less below proposed finished grade, remedial grading by moisture conditioning in-place, followed by thorough recompaction in accordance with the applicable grading guidelines herein may be attempted. If the desired results are not achieved, all affected materials should be overexcavated and replaced as compacted fill in accordance with the slope repair recommendations herein. If field conditions dictate, the geotechnical consultant may recommend other slope repair procedures. Section 6 - Excavations F:\10-6766\PRELIMINARY GEOTECHNICAL invesligation.doc Appendix D Page D-3 Standard Grading Specifications ^__^_^_____„___ 6.1 Unsuitable Materials Materials that 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. Material identified by the geotechnical consultant as unsatisfactory due to its moisture conditions should be overexcavated; moisture conditioned as needed, to a uniform at or above optimum moisture condition before placement as compacted fill. If during the course of grading adverse geotechnical conditions are exposed which were not anticipated in the preliminary soil report as determined by the geotechnical consultant additional exploration, analysis, and treatment of these problems may be recommended. 6.2 Cut Slopes Unless otherwise recommended by the geotechnical consultant and approved by the regulating agencies, permanent cut slopes should not be steeper than 2:1 (horizontal: vertical). The geotechnical consultant should observe cut slope excavation and if these excavations expose loose cohesionless, significantly fractured or otherwise unsuitable material, the materials should be overexcavated and replaced with a compacted stabilization fill. If encountered specific cross section details should be obtained from the Geotechnical Consultant. When extensive cut slopes are excavated or these cut slopes are made in the direction of the prevailing drainage, a non-erodible diversion swale (brow ditch) should be provided at the top of the siope. 6.3 Pad Areas All lot pad areas, including side yard terrace containing both cut and fill materials, transitions, located less than 3 feet deep should be overexcavated to a depth of 3 feet and replaced with a uniform compacted fill blanket of 3 feet. Actual depth of overexcavation may vary and should be delineated by the geotechnical consultant during grading. For pad areas created above cut or natural slopes, positive drainage should be established away from the top-of-slope. This may be accomplished utilizing a berm drainage swale and/or an appropriate pad gradient. A gradient in soil areas away from the top-of-slopes of 2 percent or greater is recommended. Section 7 - Compacted Fill All fill materials should have fill quality, placement, conditioning and compaction as specified below or as approved by the geotechnical consultant. 7.1 Fill Material Qualitv Excavated on-site or import materials which are acceptable to the geotechnical consultant may be utilized as compacted fill, provided trash, vegetation and other deleterious materials are removed prior to placement. All import materials anticipated for use on-site should be sampled tested and approved prior to and placement is in conformance with the requirements outlined. F:\I0-6766\PRELIMINARY GEOTECHNICAL investigation.doc Appendix D Page D-4 Standard Grading Specifications Rocks 12 inches in maximum and smaller may be utilized within compacted fill provided sufficient fill material is placed and thoroughly compacted over and around all rock to effectively fill rock voids. The amount of rock should not exceed 40 percent by dry weight passing the 3/4- inch sieve. The geotechnical consultant may vary those requirements as field conditions dictate, Where rocks 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 recommendations below. Rocks greater than four feet should be broken down or disposed off-site. 7.2 Placement of Fill Prior to placement of fill material, the geotechnical consultant should inspect the area to receive fill. After inspection and approval, the exposed ground surface should be scarified to a depth of 6 to 8 inches. The scarified material should be conditioned (i.e. moisture added or air dried by continued discing) to achieve a moisture content at or slightly above optimum moisture conditions and compacted to a minimum of 90 percent of the maximum density or as otherwise recommended in the soils report or by appropriate government agencies. Compacted fill should then be placed in thin horizontal lifts not exceeding eight inches in loose thickness prior to compaction. Each lift should be moisture conditioned as needed, thoroughly blended to achieve a consistent moisture content at or slightly above optimum and thoroughly 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. The contractor should have suitable and sufficient mechanical compaction equipment and watering apparatus on the job site to handle the amount of fill being placed in consideration of moisture retention properties of the materials and weather conditions. When placing fill in horizontal lifts adjacent to areas sloping steeper than 5:1 (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 six-foot wide benches and a minimum of four 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 after keying and benching until the geotechnical consultant has reviewed the area. 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 of fill. 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 of 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. Prior to placement of additional compacted fill following an overnight or other grading delay, the exposed surface or previously compacted fill should be processed by scarification, moisture F.\I0-6766\PRELIMINARY GEOTECHNICAL investisalion.doc Appendix D Page D-5 Standard Grading Specifications conditioning as needed to at or slightly above optimum moisture content, thoroughly blended and recompacted to a minimum of 90 percent of laboratory maximum dry density. Where unsuitable materiats exist to depths of greater than one foot, the unsuitable materials should be over- excavated. Following a period of flooding, rainfaU or overwatering by other means, no additional fill should be placed until damage assessments have been made and remedial grading performed as described herein. Rocks 12 inch in maximum dimension and smaller may be utilized in the compacted fill provided the fill is placed and thoroughly compacted over and around all rock. No oversize material should be used within 3 feet of finished pad grade and within 1 foot of other compacted fill areas. Rocks 12 inches up to four feet maximum dimension should be placed below the upper 5 feet of any fill and should not be closer than 11 feet to any slope face. These recommendations 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 those 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 contractor should assist the geotechnical consultant and/or his representative by digging test pits for removal determinations and/or for testing compacted fill. The contractor should provide this work at no additional cost to the owner or contractor's client. Fill should be tested by the geotechnical consultant for compliance with the recommended relative compaction and moisture conditions. Field density testing should conform to ASTM Method of Test D 1556-82, D 2922-81. Tests should be conducted at a minimum of two vertical feet or 1,000 cubic yards of fill placed. Actual test intervals may vary as field conditions dictate. Fill found not to be in conformance with the grading recommendations should be removed or otherwise handled as recommended by the geotechnical consultant. 7.3 Fill Slopes Unless otherwise recommended by the geotechnical consultant and approved by the regulating agencies, permanent fill slopes should not be steeper than 2:1 (horizontal: vertical), Except as specifically recommended in these grading guidelines compacted fill slopes should be over-built and cut back to grade, exposing the firm, compacted fill inner core. The actual amount of overbuilding may vary as field conditions dictate. If the desired results are not achieved, the existing slopes should be overexcavated and reconstructed under the guidelines of the geotechnical consuhant. The degree of overbuilding shall be increased until the desired compacted slope surface condition is achieved. Care should be taken by the contractor to provide thorough mechanical compaction to the outer edge ofthe overbuih slope surface. F:\I0-6766\PRELiMINARY GEOTECHNICAL invesligation.doc Appendix D Page D-6 Standard Grading Specifications At the discretion of the geotechnical consultant, slope face compaction may be attempted by conventional construction procedures including backrolling. The procedure must create a firmly compacted material throughout the entire depth ofthe slope face to the surface of the previously compacted firm fill intercore. During grading operations, care should be taken to extend compactive effort to the outer edge of the slope. Each lift should extend horizontally to the desired finished slope surface or more as needed to ultimately established desired grades. Grade during construction should not be allowed to roll off at the edge of the slope. It may be helpful to elevate slightly the outer edge of the slope. Slough resulting from the placement of individual lifts should not be allowed to drift down over previous lifts. At intervals not exceeding four feet in vertical slope height or the capability of available equipment, whichever is less, fill slopes should be thoroughly dozer trackrolled. For pad areas above fill slopes, positive drainage should be established away from the top-of-slope. This may be accomplished using a berm and pad gradient ofat least 2 percent. Section 8 - Trench Backfill Utility and/or other excavation of trench backflll should, unless otherwise recommended, be compacted by mechanical means. Unless otherwise recommended, the degree of compaction should be a minimum of 90 percent of the laboratory maximum density. Within slab areas, but outside the influence of foundations, trenches up to one foot wide and two feet deep may be backfilled with sand 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. 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, which should be thoroughly jetted in-place above the conduit, prior to 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. Section 9 - Drainage Where deemed appropriate by the geotechnical consuftant, canyon subdrain systems should be installed in accordance. Typical subdrains for compacted fill buttresses, slope stabilization or sidehill masses, should be installed in accordance with the specifications. F:\I0-6766\PRELIMINARY GEOTECHNICAL iiivestigalion.doc Appendix D P^S^ ^""^ Standard Grading Specifications ^— Roof, pad and slope drainage should be directed away from slopes and areas of structures to suitable disposal areas via non-erodible devices (i.e., gutters, downspouts, and concrete swales). For drainage in extensively landscaped areas near structures, (i.e., within four feet) a minimum of 5 percent gradient away from the structure should be maintained. Pad drainage of at least 2 percent should be maintained over the remainder ofthe site. 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 could be detrimental to slope stability and foundation performance. Section 10 - Slope Maintenance 10.1 - Landscape Plants To enhance surficial slope stability, slope planting should be accomplished at the completion ot grading Slope planting should consist of deep-rooting vegetation requinng little watering. Plants native to the southem California area and plants relative to native plants are generally desirable. Plants native to other semi-arid and arid areas may also be appropriate. A Landscape Architect should be the best party to consuft regarding actual types of plants and plantmg configuration. 10.2 - Irrigation . Irrigation pipes should be anchored to slope faces, not placed in trenches excavated into slope faces. Slope irrigation should be minimized. If automatic timing devices are utilized on irrigation systems, provisions should be made for interrupting normal irrigation during penods of rainfall. 10.3-Repair , , ^ . As a precautionary measure, plastic sheeting should be readily available, or kept on hand, to protect all slope areas from saturation by periods of heavy or prolonged rainfall. This measure is strongly recommended, beginning with the period prior to landscape planting. If slope failures occur, the geotechnical consultant should be contacted for a field review of site conditions and development of recommendations for evaluation and repair. If slope failures occur as a result of exposure to period of heavy rainfall, the failure areas and currently unaffected areas should be covered with plastic sheeting to protect against additional saturation. F \10-6766\PRELIMINARY GEOTECHNiCAL invesligaLion.doc