Loading...
HomeMy WebLinkAboutCDP 04-42; North County Pontiac/GMC; Geotechnical Investigation; 2004-01-08REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Hummer Dealership Weseloh Chevrolet Hummer 5335 Paseo del Norte Carlsbad, California JOB NO. 03-8538 08 January 2004 Prepared for: JS MORGAN CONSTRUCTION, INC. Attn: Mr. John Morgan 0?^ GEOTECHNICAL EXPLORATION, INC. SOIL 8c FOUNDATION ENGINEERING • GROUNDWATER HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY 08 January 2004 WESELOH CHEVROLET HUMMER job No. 03-8538 c/o JS Morgan Construction, Inc. 28570 Marguerite Parkway, Suite #203 Mission Viejo, CA 92692 Attn: Mr. John Morgan Subject: Report of Preliminary Geotechnical Investiaatinn Proposed Hummer Dealership Weseloh Chevrolet Hummer 5335 Paseo del INorte Carlsbad, California Dear Mr. Morgan: In accordance with your request and our proposal dated October 1 2003 Geotechnical Exploration, Inc. has prepared this report of geotechnical investigation of the soil conditions in the area of the proposed Hummer Dealership ^^°^3Ssociated improvements. The field work was performed on November 17, In our opinion, the building site should be suited for the proposed building and associated improvements provided the conclusions and recommendations presented in this report are incorporated in the design and construction. This opportunity to be of service is sincerely appreciated. Should you have any questions concerning the following report, please do not hesitate to contact us Reference to our Job No. 03-8538 will expedite a response to your inquiries. Respectfully submitted. GEOTECHNICAL EXPLORATION, INC. JaiflTirtrCerros, P.E Senior Geotechnical Engineer R.C.E. 34422/G.E. 2007 7420 TRADE STREET SAN DIEGO, CA 92121 • (858) 549-7222 • FAX: (858) 549-1604 • E-MAIL: geotech@ixpres.com TABLE OF CONTENTS PAGE I. EXECUTIVE SUMMARY 1 II. SITE DESCRIPTION 2 III. FIELD INVESTIGATION 3 IV. SOIL DESCRIPTION 4 V. LABORATORY TESTS 5 VI. GROUNDWATER 7 VII. CONCLUSION AND RECOMMENDATIONS 7 VIII. GRADING NOTES 18 IX. LIMITATIONS I9 FIGURES I. Vicinity Map II. Site Plan Illa-d. Exploratory Boring Logs IV. Laboratory Data APPENDICES A. Unified Soil Classification System B. General Earthwork Specifications REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Hummer Dealership Weseloh Chevrolet Hummer 5335 Paseo del Norte Carlsbad, California JOB NO. 03-8538 The following report presents the findings and recommendations of Geotechnical Exploration, Inc. for the proposed project (for Vicinity Map see Figure No. I). I. EXECUTIVE SUMMARY It is our understanding, based on communications with Mr. John Morgan of JS Morgan Construction and a review of plans prepared by Mr. Rick Guina, Architect, that it is proposed to develop the site to receive a new 6,826 square foot Hummer Dealership service building and associated improvements (for Site Plan see Figure No. II). The existing site is currently developed with several automobile dealership buildings, paved parking and driveway areas, and associated improvements. The proposed structure is to be located at the northeast end of an existing auto dealership service building at the north end ofthe site and is to consist of a roughly pentagonal-shaped, single-story structure utilizing standard-type building materials with conventional shallow footings and concrete slab-on-grade. Our current investigation revealed that the site is underlain by approximately 4 to 5.5 feet of medium dense, well-compacted fill soils underlain by medium dense to dense formational terrace deposits. Based on data obtained from our exploratory borings at the site, it appears that the existing fill soils are well compacted, therefore, only shallow surficial remedial grading, to approximately 1 foot in depth, will be necessary to develop the site. With the above in mind, the Scope of Work is briefly outlined as follows: Proposed Hummer Dealership job No. 03-8538 Carlsbad, California Page 2 1. Identify and classify the surface and subsurface soils in the area of the proposed structure, in conformance with the Unified Soil Classification System (refer to Figure No. Ill and Appendix A). 2. Evaluate the condition of the existing fill soils and formational materials. 3. Recommend the necessary site preparation procedures. 4. Recommend the allowable bearing capacities for the on-site fill soils. 5. Recommend preliminary foundation design information and provide active and passive earth pressures to be utilized in design of foundation structures. 6. Evaluate the settlement potential of the existing bearing soils under the proposed structural loads. II. SITE DESCRIPTION The property is known as Assessor's Parcel No. 211-060-10-00, a portion of Lot 2 according to Recorded Map 7492, in the City of Carlsbad, County of San Diego, State of California. The entire site, consisting of approximately 5.84 acres, is located at 5335 Paseo del Norte, in the City of Carlsbad. The property is bordered on the north by Cannon Road; on the south by a similar automobile dealership property; on the east by Paseo del Norte; and on the west by Interstate 5. The existing building pad was graded approximately 28 years ago. Five auto dealership buildings currently exist on the site. The existing building site is Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 3 pentagonal-shaped with its long axis in the north-south direction. Paved parking areas and driveways surround the existing structures. The proposed Hummer addition is to be located at the northeast end of the existing automobile dealership property. The site consists of a relatively level building pad area with a gentle pavement slope to the east (towards Paseo del Norte). The elevation of the building pad is approximately 70 feet above mean sea level (MSL). Survey information concerning approximate elevations across the site was obtained from a Preliminary Site Plan prepared by Rick Guina, Architect, dated November 19, 2003. III. FIELD INVESTIGATION Four exploratory borings were placed on the site in the area where the new building is to be located (for exploratory boring locations, see Figure No. II). The soils encountered in the borings were logged by our field representative, and samples were taken of the predominant soils throughout the field operation. Exploratory excavation logs have been prepared on the basis of our observations and the results have been summarized on Figure No. III. The predominant soils have been classified in conformance with the Unified Soil Classification System (refer to Appendix A). In-place samples were obtained by driving a 3-inch outside-diameter (O.D.) by 2- 3/8-inch inside-diameter (I.D.) split-tube sampler a distance of 12 inches. Also, the Standard Penetration Test was performed by using a 140-pound weight falling 30 inches to drive a 2-inch O.D. by 1-3/8-inch I.D. sampler tube a distance of 12 inches. (Twm Proposed Hummer Dealership Carlsbad, California Job No. 03-8538 Page 4 The number of blows required to drive the sampler the given distance was recorded for use in density determination. The following chart provides an in-house correlation between the number of blows and the relative density of the soil for the Standard Penetration Test and the 3-inch sampler. ^^ii^ii^l^^ 1 c:. :t £^.!;i. i.,|^^^^^^^Sp Sand & Silt Very loose 0-4 0-7 Loose 5-10 8-20 Medium 11-30 21-53 Dense 31-50 54-98 Very dense Over 50 Over 98 Clay Very soft 0-2 0-2 Soft 3-4 3-4 Firm 5-8 5-9 Stiff 9-15 10-18 Very stiff 16-30 19-45 Hard 31-60 46-90 Very hard Over 60 Over 90 IV. SOIL DESCRIPTION Our field investigation and review of pertinent geologic maps and reports indicate that artificial fill soils and medium dense to dense formational materials underlie the site. Artificial Fill (Oaf): The site is underlain by approximately 4 to 5.5 feet of fill soil. The encountered fill is medium dense, well compacted and consists of damp to moist, tan-brown to red-brown and gray-brown, silty fine to medium sand. The fill soils are considered to have a very low expansion potential. These materials are considered suitable for the proposed development. The upper 1 foot of the fill soils Proposed Hummer Dealership Carlsbad, California Job No. 03-8538 Page 5 will require removal, moisture conditioning and recompaction. Refer to Figure Nos. Ill and IV for details. Terrace Deposits (Ot): The fill soils are underlain at depth by medium dense to dense, poorly to moderately well cemented, damp, red-brown to tan-orange and orange-brown, silty fine to medium sand. The formational terrace deposits are considered to have low consolidation and expansion potential characteristics. Refer to Figure No. III. V. LABORATORY TESTS The following laboratory tests were performed on disturbed and relatively undisturbed soil samples in order to evaluate their physical and mechanical properties and their ability to support the proposed structure. The following tests were conducted on the sampled soils: 1. Moisture Content (ASTM D2216-98) 2. Density Measurements (ASTM D1188-90 and D1556-98) 3. Moisture/Density Relations (ASTM Dl557-98, Method A) 4. Mechanical Analysis (ASTM D422-98) 5. Standard Penetration Test and Split Barrel Sampling (ASTM D1586-99 and D1587-94) The moisture content of a soil sample is a measure of the weight of water, expressed as a percentage ofthe dry weight ofthe sample. The relationship between the moisture and density of remolded soil samples gives qualitative information regarding the soil strength characteristics and compaction soil conditions to be anticipated during any future grading operation. Proposed Hummer Dealership Carlsbad, California Job No. 03-8538 Page 6 The Mechanical Analysis Test was used to aid in the classification of the soils according to the Unified Soil Classification System. The expansion potential ofthe on-site soils is determined, when necessary, utilizing the Uniform Building Code Test Method for Expansive Soils (UBC Standard No. 29- 2). In accordance with the UBC (Table 18-1-B), expansive soils are classified as follows: EXPANSION INDEX POTENTIAL EXPANSION 0 to 20 Very low 21 to 50 Low 51 to 90 Medium 91 to 130 High Above 130 Very high According to the UBC Classification of Expansive Soils and based on visual evaluation, the sampled soils on the site have a very low to low expansion potential, with a maximum expansion index of less than 50. Based on laboratory test data, our observations of the primary soil types on the project, and our previous experience with laboratory testing of similar soils, our Geotechnical Engineer has provided conservative values for friction angle, coefficient of friction, and cohesion to those on-site soils which will have significant lateral support or bearing functions on the project. The assigned values have been utilized in determining the recommended bearing value as well as active and passive earth pressure design criteria. Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 7 VI. GROUNDWATER Groundwater was not encountered during the course of our field investigation and we do not expect significant groundwater problems to develop in the future - if the property is developed with good drainage (as presently proposed) and drainage is properly maintained. It should be kept in mind that any required grading operations may change surface drainage patterns and/or reduce permeabilities due to the densification of compacted soils. Such changes of surface and subsurface hydrologic conditions, plus irrigation of landscaping or significant increases in rainfall, may result in the appearance of surface or near-surface water at locations where none existed previously. The damage from such water is expected to be localized and cosmetic in nature, if good positive drainage is implemented, as recommended in this report, during and at the completion of construction. Water conditions, where suspected or encountered during grading operations, should be evaluated and remedied by the project civil and geotechnical consultants. The project developer, however, must realize that post-construction appearances of groundwater may have to be dealt with on a site-specific basis. VII. CONCLUSIONS AND RECOMMENDATIONS The following conclusions and recommendations are based upon the practical field investigation conducted by our firm, and resulting laboratory tests, in conjunction with our knowledge and experience with the soils in the Carlsbad area ofthe County of San Diego. Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 8 Our investigation revealed the site is underlain by medium dense to dense formational terrace deposits with approximately 4 to 5.5 feet of medium dense, well-compacted fill in the proposed building area. It is recommended that the upper 1 foot of the fill soils be removed, moisture-conditioned and recompacted as part of site preparation before additional fills are placed or structures are built. A. Preparation of Soils for Site Development 1. Asphalt pavement, other improvements, and vegetation on the site must be removed prior to the preparation of the building pad and/or areas to receive structural improvements. 2. In order to provide a uniform, firm soils base for the proposed structure addition and major improvements, the existing fill soil to a depth of 1 foot shall be excavated to expose properly compacted fill, as per the indications of our field representative. The bottom of the excavation shall be scarified 6 inches as a minimum. The excavated fill soils shall be cleaned of any debris and deleterious materials, watered to approximately optimum moisture content, placed and compacted to at least 90 percent of Maximum Dry Density, in accordance with ASTM D1557-98 standards. Foundation bottoms shall consist entirely of properly compacted fill soils. Any areas yielding under the rolling of heavy equipment (indicating the presence of loose or soft soils) shall be removed and properly recompacted. Areas supporting improvements (such as driveways and parking areas) should be prepared in a like manner. 3. No uncontrolled fill soils shall remain on the site after completion of any future site work. In the event that temporary ramps or pads are constructed mi Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 9 of uncontrolled fill soils, the loose fill soils shall be removed and/or recompacted prior to completion ofthe grading operation. 4. Any buried objects or abandoned utility lines, etc., which might be discovered in the construction areas shall be removed and the excavation properly backfilled with approved on-site or imported fill soils and compacted to at least 90 percent of Maximum Dry Density. 5. Any backfill soils placed in utility trenches or behind retaining walls that support exterior structures and other improvements (such as sidewalks, driveways, pavements, etc.) shall be compacted to at least 90 percent of Maximum Dry Density. Backfill soils placed behind retaining walls shall be installed as early as the retaining walls are capable of supporting lateral loads. B. Desian Parameters for Proposed Foundations 6. For foundation design of new footings, based on the assumption that new footings will be placed at least 18 inches as measured from the adjacent ground surface into properly compacted on-site soils, we provide a allowable soil bearing capacity equal to 2,000 pounds per square foot (psf) for properly compacted fill. This applies to footings at least 18 inches into the bearing soils and at least 12 inches in width. For wider and/or deeper footings, the allowable soil bearing capacity may be calculated based on the following equation: Qa = 1000D-I-500W for footings in compacted fill where Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 10 "Qa" is the allowable soil bearing capacity (irt psf); "D" is the depth of the footing (in feet) as measured from the lowest adjacent grade; and "W" is the width ofthe footing (in feet). The allowable soil bearing capacity may be increased one-third for analysis including wind or earthquake loads. The maximum total allowable soil bearing capacity for dense fill soils is 4,000 psf. We recommend that all footings be founded either entirely in compacted fill. 7. The passive earth pressure of the encountered properly compacted fill soils (to be used for design of shallow foundation and footings to resist the lateral forces) shall be based on an Equivalent Fluid Weight of 300 pounds per cubic foot. This passive earth pressure shall only be considered valid for design if the ground adjacent to the foundations structure is essentially level for a distance of at least three times the total depth of the foundation. 8. A Coefficient of Friction of 0.40 times the dead load may be used to calculate friction force between the bearing soils and concrete wall foundations or structure foundations and floor slabs. 9. The following table summarizes site-specific seismic design criteria to calculate the base shear needed for the design of the residential structure. The design criteria was obtained from the California Building Code (2001 edition) based on the site's soil profile and the distance to the closest active fault. Proposed Hummer Dealership Carlsbad, California Job No. 03-8538 Page 11 Parameter Value Reference Seismic Zone Factor, Z 0.40 Table 16-1 Soil Profile Type Sc Table 16-J Seismic Coefficient, Ca 0.40Na Table 16-Q Seismic Coefficient, Cv 0.56Nv Table 16-R Near-Source Factor, Na 1.3 Table 16-S Near-Source Factor, Nv 1.6 Table 16-T Seismic Source Type B Table 16-U 10. Our experience indicates that, for various reasons, footings and slabs occasionally crack, causing ceramic tiles and brittle surfaces to become damaged. Therefore, we recommend that all conventional shallow footings and slabs-on-grade contain at least a minimum amount of reinforcing steel to reduce the separation of cracks, should they occur. 10.1 A minimum of steel for continuous footings should include at least four No. 4 steel bars continuous, with two bars near the bottom of the footing and two bars near the top. A minimum clearance of 3 inches shall be maintained between steel reinforcement and the bottom or sides of the footing. 10.2 Isolated square footings should contain, as a minimum, a grid of three No. 4 steel bars on 12-inch centers, both ways, with no less than three bars each way. 10.3 The interior floor slab should be a minimum of 5 inches actual thickness and be reinforced with No. 4 bars on 18-inch centers, both ways, placed at midheight in the slab. Slabs with finish floor coverings shall be underlain by a 2-inch-thick layer of clean sand (S.E. = 30 or greater) overlying a moisture retardant membrane over 2 inches of Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 12 sand. Slab subgrade soil shall be verified by a Geotechnical Exploration, Inc. representative to have the proper moisture content within 48 hours prior to placement of the vapor barrier and pouring of concrete. All new slabs shall be built on properly recompacted fill soil. If the interior slabs are intended to support heavy concentrated loads (such as the ones produced by heavily loaded shelves, forklifts, etc.), then the slabs shall be reinforced as required by a structural engineer. For interior slabs in the service area supporting vehicular loads, we recommend that a minimum 4-inch-thick Class II base layer be placed under the proposed slab (in lieu of 4 inches of sand) with a moisture barrier at mid-thickness. We recommend the project Civil/Structural Engineer incorporate isolation joints and sawcuts to at least one-fourth the thickness ofthe slab in any floor designs. The joints and cuts, if properly placed, should reduce the potential for random shrinkage cracking. In no case, however, shall control joints be spaced farther than 15 feet apart. Re-entrant corners shall also be provided with control joints or additional steel reinforcing. Due to a number of reasons (such as base preparation, construction techniques, curing procedures, and normal shrinkage of concrete), some cracking of slabs can still be expected. Control joints shall be placed within 12 hours after concrete placement (or as soon as the concrete is set and raveling does not occur while cutting). Control joint spacing may be increased to 25 feet if steel reinforcing (consisting of No. 4 bars every 18 inches apart) is used. NOTE: The project Civil/Structural Engineer shall review all reinforcing schedules. The reinforcing minimums recommended herein are not to be construed as structural designs, but primarily as minimum safeguards to Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 13 reduce possible crack separations. The actual reinforcing schedule shall be as per the direction of the Civil/Structural Engineer. Based on our laboratory test results and our experience with the soil types on the subject site, the dense natural soils and properly compacted fill soils should experience differential angular rotation of less than 1/240 under the allowable loads. The maximum differential settlement across the structure and footings when founded on properly compacted fill or dense natural soils shall be on the order of 1 inch. 11. As a minimum for protection of on-site improvements, it is recommended that all nonstructural concrete slabs (such as patios, sidewalks, etc.), be founded on properly compacted, moisture-conditioned and tested fill or dense native formation and underlain by at least 12 inches of low expansive potential, properly compacted soils, with No. 3 steel reinforcing bars at 18- inch centers at midheight of the slab, and contain adequate isolation and control joints. The performance of on-site improvements can be greatly affected by soil base preparation and the quality of construction. It is therefore important that all improvements are properly designed and constructed for the existing soil conditions. The improvements should not be built on loose soils or fills placed without our observations and testing. Any rigid improvements founded on the existing loose surface soils can be expected to undergo movement and possible damage and is therefore not recommended. Geotechnical Exploration, Inc. takes no responsibility for the performance of the improvements built or loose or inadequately compacted fills. Any exterior area to receive concrete improvements shall be verified for compaction and moisture within 48 hours prior to concrete placement. Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 14 For exterior slabs with the minimum shrinkage reinforcement, control joints shall be placed at spaces no farther than 15 feet apart or the width of the slab, whichever is less, and also at re-entrant corners. Control joints in exterior slabs shall be sealed with elastomeric joint sealant. The sealant shall be inspected every 6 months and be properly maintained. Control joints shall penetrate at least one-quarter the thickness of the slab. 12. Pavement design sections will depend largely on the subgrade soil conditions exposed after grading and should be based on R-value test results. These tests should be performed after completion ofthe grading operation. All contemporary pavement section design methods assume compaction of the upper 6 inches of subgrade soil (dense ground or compacted fill) and/or all base material to at least 95 percent of Maximum Dry Density. We therefore recommend that the upper 6 inches of foundation soils and/or all base materials beneath driveway and parking area pavements be scarified, moisture conditioned, and compacted to a minimum of 95 percent of Maximum Dry Density. This compaction recommendation also applies to the upper soils in backfilled trenches or behind retaining walls that support pavement sections. The upper 2 feet of parking lot areas shall be properly compacted to at least 90 percent of Maximum Dry Density; the subgrade shall be compacted to at least 95 percent of Maximum Dry Density. 13. For concrete pavement, we recommend that the compressive strength f'c be at least 4,500 psi at 28 days of age and the slab thickness be not less than 51/2 inches thick, with control joints no farther than 15 feet apart. Subgrade soils shall be properly compacted and moisture conditioned before any base and/or concrete placement. This pavement section is adequate for an Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 15 average daily truck traffic not exceeding 10 trucks, and assuming an R-value of at least 29. No. 6 dowels shall be provided every 12 inches in the longitudinal joint within 30 feet of outside pavement, and at transverse joints near free ends of pavement. Other longitudinal joints will need to be provided with keyed joints. Subgrade surface and any base layers shall be compacted to at least 95 percent of Maximum Dry Density (ASTM D1557-98). For asphalt concrete (A.C.) placement, we recommend a preliminary section of 3 inches of A.C. on 8 inches of Class II base gravel on properly compacted subgrade for heavy traffic areas, and 3 inches of AC on 5 inches of Class II base for parking stalls. The subgrade and base shall be compacted to at least 95 percent of Maximum Dry Density. The definitive pavement cross sections shall be established after rough grading is completed and shall be based on R-value soil tests performed on subgrade soils. C. Floor Slab Vapor Transmission 14. Vapor moisture can cause some problems on moisture sensitive floors, some floor sealers, or sensitive equipment in direct contact with the floor, in addition to mildew and staining on slabs, walls and carpets. 15. The common practice in Southern California is to place vapor retarders made of PVC, or of polyethylene. PVC retarders are made in thickness ranging from 10- to 60-mil. Polyethylene retarders, called visqueen, range from 5- to 10-mil in thickness. The thicker the plastic, the stronger the resistance will be against puncturing. Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 16 16. Although polyethylene (visqueen) products are most commonly used, products such as Vaporshield possess much higher tensile strength and are more specifically designed for and intended to retard moisture transmission into concrete slabs. The use of Vaporshield or equivalent is highly recommended when a structure is intended for moisture-sensitive floor coverings or uses. 17. The vapor retarders need to have joints lapped and sealed with mastic or manufacturer's recommended tape for additional protection. To provide some protection to the moisture retarder, a layer of at least 2 inches of clean sand on top and 2 inches at the bottom shall also be provided. No heavy equipment, stakes or other puncturing instruments shall be used on top of the liner before or during concrete placement. In actual practice, stakes are often driven through the retarder material, equipment is dragged or rolled across the retarder, overlapping or jointing is not properly implemented, etc. All these construction deficiencies reduce the retarder's effectiveness. The vapor retarders are not waterproof. They are intended to help prevent or reduce capillary migration of vapor through the soil into the pores of concrete slabs. Other waterproofing systems must supplement vapor retarders if full waterproofing is desired. The owner should be consulted to determine the specific level of protection required. D. Site Drainaae Considerations 18. Adequate measures shall be taken to properly finish-grade the building site after the structure addition and other improvements are in place. Drainage waters from this site and adjacent properties are to be directed away from foundations, floor slabs, and footings, and onto the natural drainage direction Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 17 for this area or into properly designed and approved drainage facilities. Roof gutters and downspouts should be installed on the structure, with the runoff directed away from the foundations via closed drainage lines. Proper subsurface and surface drainage will help minimize the potential for waters to seek the level of the bearing soils under the foundations, footings and floor slabs. Failure to observe this recommendation could result in undermining and possible differential settlement of the structure or other improvements on the site. Currently, the Uniform Buiiding Code requires a minimum 2- percent surface gradient for proper drainage of building pads unless waived by the building official. Concrete pavement may have a minimum gradient of 0.5-percent. In addition, appropriate erosion control measures shall be taken at all times during and after construction to prevent surface runoff waters from entering footing excavations or ponding on finished building pad areas. 19. Planter areas, flower beds and planter boxes shall be sloped to drain away from the foundations, footings, and floor slabs at a gradient of at least 5 percent within 5 feet from the perimeter walls. Any planter areas adjacent to the building or surrounded by concrete improvements shall be provided with sufficient area drains to help with rapid runoff disposal. No water shall be allowed to pond adjacent to the building or other improvements. Planter boxes shall be constructed with a closed bottom and a subsurface drain, installed in gravel, with the direction of subsurface and surface flow away from the slopes, foundations, footings, and floor slabs, to an adequate drainage facility. Sufficient area drains and proper surface gradient shall be provided throughout the project. Roof gutter and downspouts shall be tied to storm drain lines. Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 18 E. General Recommendations 20. Following placement of any concrete floor slabs, sufficient drying time must be allowed prior to placement of floor coverings. Premature placement of floor coverings may result in degradation of adhesive materials and loosening of the finish floor materials. 21. In order to minimize any work delays at the subject site during site development, this firm should be contacted 24 hours prior to any need for observation of footing excavations or field density testing of compacted fill soils. If possible, placement of formwork and steel reinforcement in footing excavations should not occur prior to observing the excavations; in the event that our observations reveal the need for deepening or redesigning foundation structures at any locations, any formwork or steel reinforcement in the affected footing excavation areas would have to be removed prior to correction of the observed problem (i.e., deepening the footing excavation, recompacting soil in the bottom ofthe excavation, etc.) VIII. GRADING NOTES Any required grading operations shall be performed in accordance with the General Earthwork Specifications (Appendix B) and the requirements of the City of Carlsbad Grading Ordinance. 22. Geotechnical Exploration, Inc. recommends that we be asked to verify the actual soil conditions revealed during site grading work and footing excavation to be as anticipated in this "Report of Preliminary Geotechnical Investigation" for the project. In addition, the compaction of any fill soils placed during site grading work must be tested by the soil engineer. It is the Proposed Hummer Dealership Job No. 03-8538 Carlsbad, California Page 19 responsibility of the grading contractor to comply with the requirements on the grading plans and the local grading ordinance. All retaining wall and trench backfill that will support structures or rigid improvements shall be properly compacted. Geotechnical Exploration, Inc. will assume no liability for damage occurring due to improperly or uncompacted backfill placed without our observations and testing. 23. It is the responsibility of the owner and/or developer to ensure that the recommendations summarized in this report are carried out in the field operations and that our recommendations for design of this project are incorporated in the structural plans. We shall be provided with the opportunity to review the project plans once they are available, to see that our recommendations are adequately incorporated in the plans. 24. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responsible for the safety of personnel other than our own on the site; the safety of others is the responsibility of the contractor. The contractor should notify the owner if he considered any of the recommended actions presented herein to be unsafe. IX. LIMITATIONS Our conclusions and recommendations have been based on all available data obtained from our field investigation and laboratory analysis, as well as our experience with the soils and formational materials located in the City of Carlsbad. Of necessity, we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is, therefore, necessary that all observations, conclusions, and recommendations be verified at the time grading rwrn Proposed Hummer Dealership Carlsbad, California Job No. 03-8538 Page 20 operations begin or when footing excavations are placed. In the event discrepancies are noted, additional recommendations may be issued, if required. The work performed and recommendations presented herein are the result of an investigation and analysis that meet the contemporary standard of care in our profession within the County of San Diego. No warranty is provided. This report should be considered valid for a period of two (2) years, and is subject to review by our firm following that time. If significant modifications are made to the building plans, especially with respect to the height and location of any proposed structures, this report must be presented to us for immediate review and possible revision. The firm of Geotechnical Exploration, Inc. shall not be held responsible for changes to the physical condition of the property, such as addition of fill soils or changing drainage patterns, which occur subsequent to issuance of this report and the changes are made without our observations, testing, and approval. Once again, should any questions arise concerning this report, please feel free to contact the undersigned. Reference to our Job No. 03-8538 will expedite a reply to your inquiries. Respectfully submitted, GEOTECHNICAL EXPLORATION, INC. Jay^. neiser Senior Project Geologist ^,._»t»J5ime A. Cerros, P.E. ^50fESs5;§% 34422/G.E. 2007 /^c>^^-.=^3^'-^enlor^ Engineer |Sf, NO.002007 I S • "^i.. i,^>'^ VICINITY MAP Proposed Weseloh Hummer Dealership 5335 Paseo del Norte Carlsbad, CA. Figure No. I Job No. 03-8538 Co SCALE: 1" = 20' AREA OF. INVESTIGATION PASEO del NORTE ^•s• 16 EXISTING DRIVEWAY -/ / CANORY 1.665 sa. FT EXISTING AUTO DEALERSHIP SERVICE BUILDING 5,270 SQ. FT Legend B-4 ASSUMED PROPERTY BOUNDARY PROPOSED STRUCTURE APPROXIMATE LOCATION OF EXPLORATORY BORING \ \ ^^]pF7777777Tt ij^tWn^ \ \ \ \ c 7xn sa f D cits n FT \ Site Overview NOT TO SCALE NOTE: This Plot Plan is not to be used for legal purposes. Locations and dimensions ore approxi- mate. Actual property dimensions and locations of utilities may be obtained from the Approved Building Plans or the "As-Built" Grading Plans. PLOT PLAN Proposed Weseloh Hummer Dealership 5335 Paseo del Norte Carlsbad, CA Figure No. II Job No. 03-8538 REFERENCE: This Plot Plan was prepared from an existing electronically transferred CAD Site Plan dated November 19, 2003 provided by RGA Design and from on-site field reconnaissance performed by GEI. 03-8538-p Geotechnical ^ Exploration, Inc, December 2003 '^EQUIPMENT Truck-mounted Auger Drill Rig DIMENSION S TYPE OF EXCAVATION 8-inch diameter Boring DATE LOGGED ^ 11-17-03 SURFACE ELEVATION ± 70' Mean Sea Level GROUNDWATER DEPTH Not Encountered LOGGED BY JKH a. UJ Q FIELD DESCRIPTION AND CLASSIFICATION DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) cn d in 3 UJ ^ UJ ^ s a: QI O o s 8? 11 < UJ Q ^5 O CO X O UJ o 05 li b „ UJ ASPHALT COrjCR£TE. 2 inches thick. •\BASE, 4 inches thick. SILTY FINE TO MEDIUM SAND, w/ some coarse rock fragments. Medium dense. Damp. Tan-brown. FILL (Qaf) SM 6.6 128.7 67 3" 6 - 10 i 1 9.5 131.5 SILTY FINE TO MEDIUM SAND, poorly to moderately cemented. Medium dense. Damp. Red-brown. TERRACE DEPOSITS (Qt) SM 5.7 126.9 38 2" 10.7 116.7 75+ 12 Bottom® 11' WATERTABLE ^ LOOSE BAG SAMPLE [T] IN-PLACE SAMPLE • DRIVE SAMPLE H] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER JOBNAME Proposed Weseloh Hummer Dealership WATERTABLE ^ LOOSE BAG SAMPLE [T] IN-PLACE SAMPLE • DRIVE SAMPLE H] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER SITE LOCATION 5335 Paseo del Norte, Carlsbad, Califomia WATERTABLE ^ LOOSE BAG SAMPLE [T] IN-PLACE SAMPLE • DRIVE SAMPLE H] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER JOB NUMBER 03-8538 FIGURE NUMBER Ilia REVIEWED BY JAC ll^^Ji Geotechnical ''Jf Exploration, Inc. LOG No. B-1 '^EQUIPMENT Truck-mounted Auger Drill Rig DIMENSION & TYPE OF EXCAVATION 8-inch diameter Boring DATE LOGGED ^ 11-17-03 SURFACE ELEVATION ± 70' Mean Sea Level GROUNDWATER DEPTH Not Encountered LOGGED BY JKH FIELD DESCRIPTION AND CLASSIFICATION DESCRIPTION AND REMARKS (Grain size. Density, Moisture, Color) li §1 UJ >_ -J. UJ CL O O S >- a >-ci 28 Q o „ UJ cn —I UJ Q- X SILTY (^IHE TO MEDIUM SAND, w/ some coarse rock fragments. Medium dense to dense. Damp. Tan-gray and brown. FILL (Qaf) 6- 10 - 12 SM I 6.2 130.3 75/ 9" SILTY FINE TO MEDIUM SAND, poorly to moderately cemented. Medium dense. Damp. Red-brown. TERRACE DEPOSITS (Qt) SM 32 SILTY FINE TO MEDIUM SAND, moderately well cemented. Dense. Damp. Tan-orange. TERRACE DEPOSITS (Qt) SM 1 2.9 103.4 Bottom® 11' 3" 2" 50+ 3" X- WATERTABLE 1^ LOOSE BAG SAMPLE [Tj IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER JOBNAME Proposed Weseloh Hummer Dealership X- WATERTABLE 1^ LOOSE BAG SAMPLE [Tj IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER SITE LOCATION 5335 Paseo del Norte, Carlsbad, Califomia X- WATERTABLE 1^ LOOSE BAG SAMPLE [Tj IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER JOB NUMBER 03-8538 FIGURE NUMBER lllb REVIEWED BY JAC IfXl^ 3i Geotechnical Exploration, Inc. LOG No. B-2 J '^EQUIPMENT Truck-mounted Auger Drill Rig DIMENSION 8 TYPE OF EXCAVATION 8-inch diameter Boring DATE LOGGED ^ 11-17-03 SURFACE ELEVATION ± 70' Mean Sea Level GROUNDWATER DEPTH Not Encountered LOGGED BY JKH X 1— Q. Ul Q FIELD DESCRIPTION AND CLASSIFICATION DESCRIPTION AND REMARKS (Grain size. Density, Moisture, Color) Ul ^ O ZD Ul >_ CL O o s 1^ ii Q >-ci z o UJ..C 2 O < ^ o UJ o cn ii d _ Ul cn —I Ul CL X ASPHALT CONCRETE. 2 Inches thick. /• ^BASE, 4 inches thick. /• SILTY FINE TO MEDIUM SAND, wl some coarse rock fragments. Medium dense. Damp to moist. Red-brown. SM m FILL (Qaf) A' 6-i 10 SILTY FINE TO MEDIUM SAND, poorly to moderately cemented. Medium dense. Damp to moist. Orange-brown. TERRACE DEPOSITS (Qt) SM becomes more dense. 12 - Bottom® 11' 46 12 2" 49 3" J[. WATERTABLE 1^ LOOSE BAG SAMPLE [T] IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER JOBNAME Proposed Weseloh Hummer Dealership J[. WATERTABLE 1^ LOOSE BAG SAMPLE [T] IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER SITE LOCATION 5335 Paseo del Norte, Carlsbad, Califomia J[. WATERTABLE 1^ LOOSE BAG SAMPLE [T] IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER JOB NUMBER 03-8538 FIGURE NUMBER llic REVIEWED BY ||^^4K Geotechnical ¥ Exploration, Inc. LOG No, B-3 ^EQUIPMENT Truck-mounted Auger Drill Rig DIMENSION & TYPE OF EXCAVATION 8-inch diameter Boring DATE LOGGED ^ 11-17-03 SURFACE ELEVATION ± 70' Mean Sea Level GROUNDWATER DEPTH Not Encountered LOGGED BY JKH FIELD DESCRIPTION AND CLASSIFICATION DESCRIPTION AND REMARKS (Grain size. Density, Moisture, Color) 1^ UJ 5sn CL 2 51 o o s < Ul o >-ci cn^ 2 o ^8 cn CQ CJ a d „ Ul cn -J Ul CL X cn =- ASPHALT CONCRETE, 3 inches thick. M BASE, 4 inches thick. SILTY FINE TO MEDIUM SAND, w/ some coarse rock fragments. Medium dense to dense. Damp. Gray-brown. FILL (Qaf) SM -hp t SILTY FINE TO MEDIUM SAND. Medium dense to dense. Damp. Red-brown. TERRACE DEPOSITS (Qt) Bottom @ 6' SM 10 12 5. WATERTABLE 1^ LOOSE BAG SAMPLE [H IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER JOBNAME Proposed Weseloh Hummer Dealership 5. WATERTABLE 1^ LOOSE BAG SAMPLE [H IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER SITE LOCATION 5335 Paseo del Norte, Carlsbad, Califomia 5. WATERTABLE 1^ LOOSE BAG SAMPLE [H IN-PLACE SAMPLE • DRIVE SAMPLE [s] SAND CONE/F.D.T. ^ ^ STANDARD PENETROMETER JOB NUMBER 03-8538 RGURE NUMBER llld REVIEWED BY iKj^ t Geotechnical "^^J Exploration, Inc. LOG No, B-4 135 130 125 120 115 110 a > UJ Q >- Q: Q 105 100 Source of Material Description of Material Test Method B-1 @ 3.0' Tan-brown Silty Fine to Medium Sand ASTM D1557 Method A TEST RESULTS Maximum Dry Density Optimum Water Conient 131.5 PCF 9.5 % ATTERBERG LIMITS Curves of 100% Saturation for Specific Gravity Equal to: 2.80 2.70 WATER CONTENT, % Geotechnical Exploration, Inc. MOISTURE-DENSITY RELATIONSHIP Figure Number: IVa Job Name: Proposed Weseloh Hummer Dealership Site Location: 5335 Paseo del Norte, Carlsbad, CalifornlE Job Number: 03-8538 U.S. SIEVE OPENING IN INCHES 6 ''3 2 1.5 1 3,4 1/2, U.S. SIEVE NUMBERS 810,416 20 30 40 50 go 100,^0200 HYDROMETER 100 95 90 85 80 75 70 65 ? >- 55 CD o: w 50 il t- 45 z Lil ^40 UJ 1 [ 35 30 25 20 15 10 5 0 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 COBBLES GRAVEL SAND SILT OR CLAY COBBLES coarse fine coarse medium fine SILT OR CLAY Specimen Identification B-1 @ 3.0' Specimen Identification B-1 @3.0' Classification Tan-brown Silty Fine to Medium Sand D100 9.5 D60 0.272 D30 0.083 D10 LL %Gravel 0.1 PL %Sand 70.8 PI Cc %Silt Cu %Clay 29.1 Geotechnical Exploration, Inc. GRAIN SIZE DISTRIBUTION Figure Number: IVb Job Name: Proposed Weseloh Hummer Dealership Site Location: 5335 Paseo del Norte, Carlsbad, Californi Job Number: 03-8538 APPENDIX A UNIFIED SOIL CLASSIFICATION CHART SOIL DESCRIPTIOIM Coarse-grained {More than half of material is larger than a No. 200 sieve) GRAVELS, CLEAN GRAVELS (More than half of coarse fraction is larger than No. 4 sieve size, but smaller than 3") GRAVELS WITH FINES (Appreciable amount) SANDS, CLEAN SANDS (More than half of coarse fraction IS smaller than a No. 4 sieve) SANDS WITH FINES (Appreciable amount) GW Well-graded gravels, gravel and sand mixtures, little or no fines. GP Poorly graded gravels, gravel and sand mixtures, little or no fines. GC Clay gravels, poorly graded gravel-sand-siit mixtures SW Well-graded sand, gravelly sands, little or no fines SP Poorly graded sands, gravelly sands, little or no fines. SM Silty sands, poorly graded sand and silty mixtures. SC Clayey sands, poorly graded sand and clay mixtures. FINE-GRAINED (More than half of material is smaller than a No. 200 sieve) SILTS AND CLAYS Liquid Limit Less than 50 Liquid Limit Greater tfian 50 HIGHLY ORGANIC SOILS ML Inorganic silts and very fine sands, rock flour, sandy silt and clayey-silt sand mixtures v/ith a slight plasticity. CL Inorganic clays of low to medium plasticity, gravelly clays, silty clays, clean clays. OL Organic silts and organic silty clays of low plasticity. MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. CH Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity. PT Peat and other highly organic soils APPENDIX B GENERAL EARTHWORK SPECIFICATIONS General The objective of these specifications is to properly establish procedures for the clearing and preparation of the existmg natural ground or properly compacted fill to receive new fill; for the selection of the fill material; and for the fill compaction and testing methods to be used. Scope of Work The earthwork includes all the activities and resources provided by the contractor to construct in a good workmanlike manner all the grades of the filled areas shown in the plans. The major items of work covered in this section include all clearing and grubbing, removing and disposing of materials, preparing areas to be filled, compacting of fill, compacting of backfills, subdrain installations, and all other work necessary to complete the grading of the filled areas. Site Visit and Site Investigation 1. The contractor shall visit the site and carefully study it, and make all inspections necessary in order to determine the full extent of the work required to complete all grading in conformance with the drawings and specifications. The contractor shall satisfy himself as to the nature, location, and extent of the work conditions, the conformation and condition of the existing ground surface; and the type of equipment, labor, and facilities needed prior to and during prosecution of the work. The contractor shall satisfy himself as to the character, quality, and quantity of surface and subsurface materials or obstacles to be encountered. Any inaccuracies or discrepancies between the actual field conditions and the drav/ings, or between the drawings and specifications, must be brought to the engineer's attention in order to clarify the exact nature of the work to be performed. 2. A soils investigation report has been prepared for this project by GEI. It is available for review and should be used as a reference to the surface and subsurface soil and bedrock conditions on this project. Any recommendations made in the report of the soil investigation or subsequent reports shall become an addendum to these specifications. Authoritv of the Soils Engineer and Enqineerinq Geologist The soils engineer shall be the owner's representative to observe and test the construction of fills. Excavation and the placing of fill shall be under the observation of the soils engineer and his/her representative, and he/she shall give a written opinion regarding conformance with the specifications upon completion of grading. The soils engineer shall have the authority to cause the removal and replacement of porous topsoils, uncompacted or improperly compacted fills, disturbed bedrock materials, and soft alluvium, and shall have the authority to approve or reject materials proposed for use in the compacted fill areas. The soils engineer shall have, in conjunction with the engineering geologist, the authority to approve the preparation of natural ground and toe-of-fill benches to receive fill material. The engineering geologist shall have the authority to evaluate the stability of the existing or proposed slopes, and to evaluate the necessity of remedial measures. If any unstable condition is being created by cutting or filling, the engineering geologist and/or soils engineer shall advise the contractor and owner immediately, and prohibit grading in the affected area until such time as corrective measures are taken. The owner shall decide all questions regarding: (1) the interpretation of the drawings and specifications, (2) the acceptable fulfillment of the contract on the part of the contractor, and (3) the matter of compensation. Appendix B Page 2 Clearinq and Grubbinq 1. Clearing and grubbing shall consist of the removal from all areas to be graded of all surface trash, abandoned improvements, paving, culverts, pipe, and vegetation (including - but not limited to - heavy weed growth, trees, stumps, logs and roots larger than 1-inch in diameter). 2. All organic and inorganic materials resulting from the clearing and grubbing operations shall be collected, piled, and disposed of by the contractor to give the cleared areas a neat and finished appearance. Burning of combustible materials on-site shall not be permitted unless allowed by local regulations, and at such times and in such a manner to prevent the fire from spreading to areas adjoining the property or cleared area. 3. It is understood that minor amounts of organic materials may remain in the fill soils due to the near impossibility of complete removal. The amount remaining, however, must be considered negligible, and in no case can be allowed to occur in concentrations or total quantities sufficient to contribute to settlement upon decomposition. Preparation of Areas to be Filled 1. After clearing and grubbing, all uncompacted or improperly compacted fills, soft or loose soils, or unsuitable materials, shall be removed to expose competent natural ground, undisturbed bedrock, or properly compacted fill as indicated in the soils investigation report or by our field representative. Where the unsuitable materials are exposed in final graded areas, they shall be removed and replaced as compacted fill. 2. The ground surface exposed after removal of unsuitable soils shall be scarified to a depth of at least 6 inches, brought to the specified moisture content, and then the scarified ground compacted to at least the specified density. Where undisturbed bedrock is exposed at the surface, scarification and recompaction shall not be required. 3. All areas to receive compacted fill, including all removal areas and toe-of-fill benches, shall be observed and approved by the soils engineer and/or engineering geologist prior to placing compacted fill. 4. Where fills are made on hillsides or exposed slope areas with gradients greater than 20 percent, horizontal benches shall be cut into firm, undisturbed, natural ground in order to provide both lateral and vertical stability. This is to provide a horizontal base so that each layer is placed and compacted on a horizontal plane. The initial bench at the toe of the fill shall be at least 10 feet in width on firm, undisturbed, natural ground at the elevation of the toe stake placed at the bottom of the design slope. The engineer shall determine the width and frequency of all succeeding benches, which will vary with the soil conditions and the steepness of the slope. Ground slopes flatter than 20 percent (5.0:1.0) shall be benched when considered necessary by the soils engineer. Fill and Backfill IVlaterial Unless otherwise specified, the on-site material obtained from the project excavations may be used as fill or backfill, provided that all organic material, rubbish, debris, and other objectionable material contained therein is first removed. In the event that expansive materials are encountered during foundation excavations within 3 feet of finished grade and they have not been properly processed, they shall be entirely removed or thoroughly mixed with good, granular material before incorporating them in fills. No footing shall be allowed to bear on soils which, in the opinion of the soils engineer, are detrimentally expansive - unless designed for this clayey condition. However, rocks, boulders, broken Portland cement concrete, and bituminous-type pavement obtained from the project excavations may be permitted in the backfill or fill with the following limitations: Appendix B Page 3 1. The maximum dimension of any piece used in the top 10 feet shall be no larger than 6 inches. 2 Clods or hard lumps of earth of 6 inches in greatest dimension shall be broken up before compacting the material in fill. 3. If the fill material originating from the project excavation contains large rocks, boulders, or hard lumps that cannot be broken readily, pieces ranging from 6 inches in diameter to 2 feet in maximum dimension may be used in fills below final subgrade if all pieces are placed in such a manner (such as windrows) as to eliminate nesting or voids between them. No rocks over 4 feet will be allowed in the fill. 4. Pieces larger than 6 inches shall not be placed within 12 inches of any structure. 5. Pieces larger than 3 inches shall not be placed within 12 inches of the subgrade for paving. 6. Rockfills containing less than 40 percent of soil passing 3/4-inch sieve may be permitted in designated areas. Specific recommendations shall be made by the soils engineer and be subject to approval by the city engineer. 7. Continuous observation by the soils engineer is required during rock placement. 8. Special and/or additional recommendations may be provided in writing by the soils engineer to modify, clarify, or amplify these specifications. 9. During grading operations, soil types other than those analyzed in the soil investigation report may be encountered by the contractor. The soils engineer shall be consulted to evaluate the suitability of these soils as fill materials. Placinq and Compactinq FiH Material 1. After preparing the areas to be filled, the approved fill material shall be placed in approximately horizontal layers, with lift thickness compatible to the material being placed and the type of equipment being used. Unless otherwise approved by the soils engineer, each layer spread for compaction shall not exceed 8 inches of loose thickness. Adequate drainage of the fill shali be provided at all times during the construction period. 2. When the moisture content of the fill material is below that specified by the engineer, water shall be added to it until the moisture content is as specified. 3. When the moisture content of the fill material is above that specified by the engineer, resulting in inadequate compaction or unstable fill, the fill material shall be aerated by blading and scarifying or other satisfactory methods until the moisture content is as specified. 4. After each layer has been placed, mixed, and spread evenly, it shall be thoroughly compacted to not less than the density set forth in the specifications. Compaction shall be accomplished with sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other approved types of acceptable compaction equipment. Equipment shall be of such design that it will be able to compact the fill to the specified relative compaction. Compaction shall cover the entire fill area, and the equipment shall make sufficient trips to ensure that the desired density has been obtained throughout the entire fill. At locations where it would be impractical due to inaccessibility of rolling compacting equipment, fill layers shall be compacted to the specified requirements by hand-directed compaction equipment. Appendix B Page 4 5. When soil types or combination of soil types are encountered which tend to develop densely packed surfaces as a result of spreading or compacting operations, the surface of each layer of fill shall be sufficiently roughened after compaction to ensure bond to the succeeding layer. 6. Unless otherwise specified, fill slopes shall not be steeper than 2.0 horizontal to 1.0 vertical. In general, fill slopes shall be finished in conformance with the lines and grades shown on the plans. The surface of fill slopes shall be overfilled to a distance from finished slopes such that it wili allow compaction equipment to operate freely within the zone of the finished slope, and then cut back to the finished grade to expose the compacted core. Alternate compaction procedures include the backrolling of slopes with sheepsfoot rollers in increments of 3 to 5 feet in elevation gain. Alternate methods may be used by the contractor, but they shall be evaluated for approval by the soils engineer. 7. Unless otherwise specified, all allowed expansive fill material shall be compacted to a moisture content of approximately 2 to 4 percent above the optimum moisture content. Nonexpansive fill shall be compacted at near-optimum moisture content. All fill shall be compacted, unless otherwise specified, to a relative compaction not less than 95 percent for fill in the upper 12 inches of subgrades under areas to be paved with asphalt concrete or Portland concrete, and not less than 90 percent for other fill. The relative compaction is the ratio of the dry unit weight of the compacted fill to the laboratory maximum dry unit weight of a sample of the same soil, obtained in accordance with A.S.T.M. D-1557 test method. 8. The observation and periodic testing by the soils engineer are intended to provide the contractor with an ongoing measure of the quality of the fill compaction operation. It is the responsibility of the grading contractor to utilize this information to establish the degrees of compactive effort required on the project. More importantly, it is the responsibility of the grading contractor to ensure that proper compactive effort is applied at all times during the grading operation, including during the absence of soils engineering representatives. Trench Backfill 1. Trench excavations which extend under graded lots, paved areas, areas under the influence of structural loading, in slopes or close to slope areas, shall be backfilled under the observations and testing of the soils engineer. All trenches not falling within the aforementioned locations shall be backfilled in accordance vvith the City or County regulating agency specifications. 2. Unless otherwise specified, the minimum degree of compaction shall be 90 percent of the laboratory maximum dry density. 3. Any soft, spongy, unstable, or other similar material encountered in the trench excavation upon which the bedding material or pipe is to be placed, shall be removed to a depth recommended by the soils engineer and replaced with bedding materials suitably densified. Bedding material shall first be placed so that the pipe is supported for the full length of the barrel vvith full bearing on the bottom segment. After the needed testing of the pipe is accomplished, the bedding shall be completed to at least 1 foot on top of the pipe. The bedding shall be properly densified before backfill is placed. Bedding shall consist of granular material with a sand equivalent not less than 30, or other material approved by the engineer. 4. No rocks greater than 6 inches in diameter will be allowed in the backfill placed between 1 foot above the pipe and 1 foot below finished subgrade. Rocks greater than 2.5 inches in any dimension will not be allowed in the backfill placed within 1 foot of pavement subgrade. Appendix B Page 5 5. Material for mechanically compacted backfill shall be placed in lifts of horizontal layers and properly moistened prior to compaction. In addition, the layers shall have a thickness compatible with the material being placed and the type of equipment being used. Each layer shall be evenly spread, moistened or dried, and then tamped or rolled until the specified relative compaction has been attained. 6. Backfill shall be mechanically compacted by means of tamping rollers, sheepsfoot rollers, pneumatic tire rollers, vibratory rollers, or other mechanical tampers. Impact-type pavement breakers (stompers) will not be permitted over clay, asbestos cement, plastic, cast iron, or nonreinforced concrete pipe. Permission to use specific compaction equipment shall not be construed as guaranteeing or implying that the use of such equipment will not result in damage to adjacent ground, existing improvements, or improvements installed under the contract. The contractor shall make his/her own determination in this regard. 7. Jetting shall not be permitted as a compaction method unless the soils engineer allows it in writing. 8. Clean granular material shall not be used as backfill or bedding in trenches located in slope areas or v/ithin a distance of 10 feet of the top of slopes unless provisions are made for a drainage system to mitigate the potential buildup of seepage forces into the slope mass. Observations and Testinq 1. The soils engineers or their representatives shall sufficiently observe and test the grading operations so that they can state their opinion as to whether or not the fill was constructed in accordance with the specifications. 2. The soils engineers or their representatives shall take sufficient density tests during the placement of compacted fill. The contractor should assist the soils engineer and/or his/her representative by digging test pits for removal determinations and/or for testing compacted fill. In addition, the contractor should cooperate with the soils engineer by removing or shutting down equipment from the area being tested. 3. Fill shall be tested for compliance with the recommended relative compaction and moisture conditions. Field density testing should be performed by using approved methods by A.S.T.M., such as A.S.T.M. D1556, D2922, and/or D2937. Tests to evaluate density of compacted fill should be provided on the basis of not less than one test for each 2-foot vertical lift of the fill, but not less than one test for each 1,000 cubic yards of fill placed. Actual test intervals may vary as field conditions dictate. In fill slopes, approximately half of the tests shall be made at the fill slope, except that not more than one test needs to be made for each 50 horizontal feet of slope in each 2-foot vertical lift. Actual test intervals may vary as field conditions dictate. 4. Fill found not to be in conformance with the grading recommendations should be removed or otherwise handled as recommended by the soils engineer. Site Protection It shall be the grading contractor's obligation to take all measures deemed necessary during grading to maintain adequate safety measures and working conditions, and to provide erosion-control devices for the protection of excavated areas, slope areas, finished work on the site and adjoining properties, from storm damage and flood hazard originating on the project. It shall be the contractor's responsibility to maintain slopes in their as-graded form until all slopes are in satisfactory compliance with the job specifications, all berms and benches have been properly constructed, and all associated drainage devices have been installed and meet the requirements of the specifications. mm Appendix B Page 6 All observations, testing services, and approvals given by the soils engineer and/or geologist shall not relieve the contractor of his/her responsibilities of performing the work in accordance with these specifications. After grading is completed and the soils engineer has finished his/her observations and/or testing of the work, no further excavation or filling shall be done except under his/her observations. Adverse Weather Conditions 1. Precautions shall be taken by the contractor during the performance of site clearing, excavations, and grading to protect the worksite from flooding, ponding, or inundation by poor or improper surface drainage. Temporary provisions shall be made during the rainy season to adequately direct surface drainage away from and off the worksite. Where low areas cannot be avoided, pumps should be kept on hand to continually remove water during periods of rainfall. 2. During periods of rainfall, plastic sheeting shall be kept reasonably accessible to prevent unprotected slopes from becoming saturated. Where necessary during periods of rainfall, the contractor shall install checkdams, desilting basins, rip-rap, sandbags, or other devices or methods necessary to control erosion and provide safe conditions. 3. During periods of rainfall, the soils engineer 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.). 4. Following periods of rainfall, the contractor shall contact the soils engineer and arrange a walk-over of the site in order to visually assess rain-related damage. The soils engineer may also recommend excavations and testing in order to aid in his/her assessments. At the request of the soils engineer, the contractor shall make excavations in order to evaluate the extent of rain-related damage. 5. Rain-related damage shall be considered to include, but may not be limited to, erosion, silting, saturation, swelling, structural distress, and other adverse conditions identified by the soils engineer. Soil adversely affected shall be classified as Unsuitable Materials, and shall be subject to overexcavation and replacement with compacted fill or other remedial grading, as recommended by the soils engineer. 6. Relatively level areas, where saturated soils and/or erosion gullies exist to depths of greater than 1.0 foot, shall be overexcavated to unaffected, competent material. Where less than 1.0 foot in depth, unsuitable materials may be processed in place to achieve near-optimum moisture conditions, then thoroughly recompacted in accordance with the applicable specifications. If the desired results are not achieved, the affected materials shall be over-excavated, then replaced in accordance with the applicable specifications. 7. In slope areas, where saturated soils and/or erosion gullies exist to depths of greater than 1.0 foot, they shall 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 presented may be attempted. If materials shall be overexcavated and replaced as compacted fill, it shall be done in accordance with the slope-repair recommendations herein. As field conditions dictate, other slope-repair procedures may be recommended by the soils engineer.