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HomeMy WebLinkAboutF - Geotechnical Investigation GEOTECHNICAL INVESTIGATION PROPOSED WAREHOUSE Beech Avenue, North of Foothill Boulevard Fontana, California For AIREF ACQUISITIONS, LLC 22885 Savi Ranch Parkway  Suite E  Yorba Linda  California  92887 voice: (714) 685-1115  fax: (714) 685-1118  www.socalgeo.com December 7, 2021 AIREF ACQUISITIONS, LLC 4675 MacArthur Court, Suite 625 Newport Beach, California 92660 Attention: Mr. Peter F. Schafer AVP, Development Project No.: 21G260-1 Subject: Geotechnical Investigation Proposed Warehouse Beech Avenue, North of Foothill Boulevard Fontana, California Mr. Schafer: In accordance with your request, we have conducted a geotechnical investigation at the subject site. We are pleased to present this report summarizing the conclusions and recommendations developed from our investigation. We sincerely appreciate the opportunity to be of service on this project. We look forward to providing additional consulting services during the course of the project. If we may be of further assistance in any manner, please contact our office. Respectfully Submitted, SOUTHERN CALIFORNIA GEOTECHNICAL, INC. Ricardo Frias, RCE 91772 Project Engineer Robert G. Trazo, GE 2655 Principal Engineer Distribution: (1) Addressee Proposed Warehouse – Fontana, CA Project No. 21G260-1 TABLE OF CONTENTS 1.0 EXECUTIVE SUMMARY 1 2.0 SCOPE OF SERVICES 3 3.0 SITE AND PROJECT DESCRIPTION 4 3.1 Site Conditions 4 3.2 Proposed Development 4 4.0 SUBSURFACE EXPLORATION 5 4.1 Scope of Exploration/Sampling Methods 5 4.2 Geotechnical Conditions 5 5.0 LABORATORY TESTING 7 6.0 CONCLUSIONS AND RECOMMENDATIONS 9 6.1 Seismic Design Considerations 9 6.2 Geotechnical Design Considerations 11 6.3 Site Grading Recommendations 13 6.4 Construction Considerations 16 6.5 Foundation Design and Construction 17 6.6 Floor Slab Design and Construction 18 6.7 Retaining Wall Design and Construction 19 6.8 Pavement Design Parameters 21 7.0 GENERAL COMMENTS 24 APPENDICES A Plate 1: Site Location Map Plate 2: Boring Location Plan B Boring Logs C Laboratory Test Results D Grading Guide Specifications E Seismic Design Parameters Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 1 1.0 EXECUTIVE SUMMARY Presented below is a brief summary of the conclusions and recommendations of this investigation. Since this summary is not all inclusive, it should be read in complete context with the entire report. Geotechnical Design Considerations • The native alluvial soils, within 4½± feet of the ground surface, generally consist of silty sands which possess variable strength and unfavorable consolidation/collapse characteristics. These soils, in their present condition, are not considered suitable for support of the foundation loads of the new structure. The deeper alluvium generally consist of well-graded sands and gravelly sands, and possesses higher strengths and densities and more favorable consolidation/collapse characteristics. • Remedial grading will be necessary to remove the undocumented fill soils in their entirety and the upper portion of the near-surface native alluvial soils and replace these materials as compacted structural fill soils. Site Preparation Recommendations • Initial site preparation should include removal of all vegetation, including tree root masses and any organic topsoil. • Remedial grading is recommended within the proposed building pad area to remove the upper portion of the native alluvial soils and replace these as compacted fill. At a minimum, the building pad area should also be overexcavated to a depth of at least 5 feet below existing grade and to a depth of at least 3 feet below proposed pad grade, whichever is greater. Overexcavation within the foundation areas is recommended to extend to a depth of at least 3 feet below proposed foundation bearing grade. • Following completion of the overexcavation, the exposed soils should be scarified to a depth of at least 12 inches, and thoroughly flooded to raise the moisture content of the underlying soils to at least 0 to 4 percent above optimum moisture content, extending to a depth of at least 24 inches. The overexcavation subgrade soils should then be recompacted to at least 90 percent of the ASTM D-1557 maximum dry density. The previously excavated soils may then be replaced as compacted structural fill. • The new pavement and flatwork subgrade soils are recommended to be scarified to a depth of 12± inches, moisture conditioned and recompacted to at least 90 percent of the ASTM D- 1557 maximum dry density. Building Foundation Recommendations • Conventional shallow foundations, supported in newly placed compacted fill. • Maximum, net allowable soil bearing pressure: 2,500 lbs/ft2. • Reinforcement consisting of at least two (2) No. 5 rebars (1 top and 1 bottom) in strip footings. Additional reinforcement may be necessary for structural considerations. Building Floor Slab Design Recommendations • Conventional Slab-on-Grade: minimum 6 inches thick. • Modulus of Subgrade Reaction: k = 150 psi/in. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 2 • Reinforcement is not expected to be necessary for geotechnical considerations. The actual thickness and reinforcement of the floor slab should be determined by the structural engineer. Pavement Design Recommendations ASPHALT PAVEMENTS (R=50) Materials Thickness (inches) Auto Parking and Auto Drive Lanes (TI = 4.0 to 5.0) Truck Traffic TI = 6.0 TI = 7.0 TI = 8.0 TI = 9.0 Asphalt Concrete 3 3½ 4 5 5½ Aggregate Base 3 4 5 5 7 Compacted Subgrade 12 12 12 12 12 PORTLAND CEMENT CONCRETE PAVEMENTS (R=50) Materials Thickness (inches) Autos and Light Truck Traffic (TI = 6.0) Truck Traffic TI = 7.0 TI = 8.0 TI = 9.0 PCC 5 5½ 6½ 8 Compacted Subgrade (95% minimum compaction) 12 12 12 12 Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 3 2.0 SCOPE OF SERVICES The scope of services performed for this project was in accordance with our Proposal No. 21P453R, dated October 19, 2021. The scope of services included a visual site reconnaissance, subsurface exploration, field and laboratory testing, and geotechnical engineering analysis to provide criteria for preparing the design of the building foundations, building floor slab, and parking lot pavements along with site preparation recommendations and construction considerations for the proposed development. The evaluation of the environmental aspects of this site was beyond the scope of services for this geotechnical investigation. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 4 3.0 SITE AND PROJECT DESCRIPTION 3.1 Site Conditions The site is located on the west side of Beech Avenue, 330± feet north of Foothill Boulevard in Fontana, California. The site is bounded to the north by a vacant lot, to the west by an existing commercial/industrial building and a vacant lot, to the south by a single-family residence and a vacant lot, and to the east by the Beech Avenue easement. The general location of the site is illustrated on the Site Location Map, included as Plate 1 of this report. The site consists of an irregular-shaped parcel, 8.38± acres in size. The site is presently vacant and undeveloped. Ground surface consists of exposed soil and cobbles with sparse grass and weed growth. One large tree is located in the central area of the site. Detailed topographic information was not available at the time of this report. Based on elevations obtained from Google Earth and visual observations made at the time of the subsurface investigation, the overall site generally slopes downward to the south at a gradient of 1.5± percent. 3.2 Proposed Development Based on a conceptual site plan provided to our office by the client, the site will be developed with one (1) new industrial building, 185,380± ft2 in size, located in the west-central area of the site. Dock-high doors will be constructed along a portion of the east building wall. The building will be surrounded by asphaltic concrete pavements in the parking and drive lanes, Portland cement concrete pavements in the loading dock areas, and limited areas of concrete flatwork and landscape planters throughout. Beech Avenue will be paved with asphaltic concrete for this new development. Detailed structural information has not been provided. It is assumed the building will be of tilt- up concrete construction, typically supported on conventional shallow foundations with a concrete slab-on-grade floor. Based on the assumed construction, maximum column and wall loads are expected to be on the order of 100 kips and 4 to 7 kips per linear foot, respectively. No significant amounts of below grade construction, such as crawl spaces or new basements, are expected to be included in the proposed development. Based on the assumed topography, cuts and fills of up to 3 to 4± feet are expected to be necessary to achieve the proposed site grades. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 5 4.0 SUBSURFACE EXPLORATION 4.1 Scope of Exploration/Sampling Methods The subsurface exploration for this project consisted of seven (7) borings advanced to depths of 5 to 25± feet below the existing site grades. All of the borings were logged during drilling by a member of our staff. The borings, except Boring No. B-7, were advanced with hollow stem augers, by a conventional truck-mounted drilling rig. Boring No. B-7 was advanced with manually operated hand auger equipment. Representative bulk and relatively undisturbed soil samples were taken during drilling. Relatively undisturbed soil samples were taken with a split barrel “California Sampler” containing a series of one inch long, 2.416± inch diameter brass rings. This sampling method is described in ASTM Test Method D-3550. In-situ samples were also taken using a 1.4± inch inside diameter split spoon sampler, in general accordance with ASTM D-1586. Both of these samplers are driven into the ground with successive blows of a 140-pound weight falling 30 inches. The blow counts obtained during driving are recorded for further analysis. Bulk samples were collected in plastic bags to retain their original moisture content. The relatively undisturbed ring samples were placed in molded plastic sleeves that were then sealed and transported to our laboratory. The approximate locations of the borings are indicated on the Boring Location Plan, included as Plate 2 in Appendix A of this report. The Boring Logs, which illustrate the conditions encountered at the boring locations, as well as the results of some of the laboratory testing, are included in Appendix B. 4.2 Geotechnical Conditions Alluvium Native alluvium was encountered at the ground surface of all boring locations, extending to at least the maximum depth explored of 25± feet below ground surface. The near-surface alluvial soils, within the upper 2½ to 4½± feet, generally consist of medium dense to dense silty fine sands and silty fine to coarse sands with varying cobble content. At depths greater than 4½± feet, the alluvial soils generally consist of medium dense to very dense fine to coarse sands with little fine to coarse gravel and occasional to abundant cobbles. Boring No. B-3 encountered gravelly fine to coarse sands from the ground surface, extending to 15± feet below ground surface. Groundwater Free water was not encountered during the drilling of any of the borings. Based on the lack of any water within the borings, and the moisture contents of the recovered soil samples, the Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 6 static groundwater table is considered to have existed at a depth in excess of 25± feet at the time of the subsurface exploration. Recent water level data was obtained from the California Department of Water Resources website, http://www.water.ca.gov/waterdatalibrary/. One monitoring well on record is located 5,121± feet north of the site. Water level readings within this monitoring well indicates a high groundwater level of 492± feet below ground surface in April 2016. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 7 5.0 LABORATORY TESTING The soil samples recovered from the subsurface exploration were returned to our laboratory for further testing to determine selected physical and engineering properties of the soils. The tests are briefly discussed below. It should be noted that the test results are specific to the actual samples tested, and variations could be expected at other locations and depths. Classification All recovered soil samples were classified using the Unified Soil Classification System (USCS), in accordance with ASTM D-2488. Field identifications were then supplemented with additional visual classifications and/or by laboratory testing. The USCS classifications are shown on the Boring Logs and are periodically referenced throughout this report. Dry Density and Moisture Content The density has been determined for selected relatively undisturbed ring samples. These densities were determined in general accordance with the method presented in ASTM D-2937. The results are recorded as dry unit weight in pounds per cubic foot. The moisture contents are determined in accordance with ASTM D-2216, and are expressed as a percentage of the dry weight. These test results are presented on the Boring Logs. Consolidation Selected soil samples have been tested to determine their consolidation potential, in accordance with ASTM D-2435. The testing apparatus is designed to accept either natural or remolded samples in a one-inch-high ring, approximately 2.416 inches in diameter. Each sample is then loaded incrementally in a geometric progression and the resulting deflection is recorded at selected time intervals. Porous stones are in contact with the top and bottom of the sample to permit the addition or release of pore water. The samples are typically inundated with water at an intermediate load to determine their potential for collapse or heave. The results of the consolidation testing are plotted on Plates C-1 through C-4 in Appendix C of this report. Maximum Dry Density and Optimum Moisture Content A representative bulk sample has been tested to determine its maximum dry density and optimum moisture content. The results have been obtained using the Modified Proctor procedure, per ASTM D-1557 and are presented on Sheet C-5 in Appendix C of this report. These tests are generally used for comparison with the densities of undisturbed field samples, and for later compaction testing. Additional testing of other soil types or soil mixes may be necessary at a later date. R-value R (resistance)-value testing was conducted on a representative sample of the near-surface soils obtained from the subject site. The R-value was determined in accordance with CA Test Method 301. This test provides a measure of the pavement support characteristics of the soils, and is Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 8 used in the pavement thickness design procedure. The result of the R-value testing is as follows: Sample ID R-Value B-7 @ 0 to 5 feet 77 Soluble Sulfates A representative sample of the near-surface soil was submitted to a subcontracted analytical laboratory for determination of soluble sulfate content. Soluble sulfates are naturally present in soils, and if the concentration is high enough, can result in degradation of concrete which comes into contact with these soils. The results of the soluble sulfate testing are presented below, and are discussed further in a subsequent section of this report. Sample Identification Soluble Sulfates (%) Sulfate Classification B-5 @ 0 to 5 feet 0.002 Not Applicable (S0) Corrosivity Testing One representative sample of the near-surface soils was submitted to a subcontracted corrosion engineering laboratory to identify potentially corrosive characteristics with respect to common construction materials. The corrosivity testing included a determination of the electrical resistivity, pH, chloride and nitrate concentrations of the soils, as well as other tests. The results of some of these tests are presented below. Sample Identification Saturated Resistivity (ohm-cm) pH Chlorides (mg/kg) Nitrates (mg/kg) B-5 @ 0 to 5 feet 10,000 7.0 20 23 Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 9 6.0 CONCLUSIONS AND RECOMMENDATIONS Based on the results of our review, field exploration, laboratory testing and geotechnical analysis, the proposed development is considered feasible from a geotechnical standpoint. The recommendations contained in this report should be taken into the design, construction, and grading considerations. The recommendations are contingent upon all grading and foundation construction activities being monitored by the geotechnical engineer of record. The recommendations are provided with the assumption that an adequate program of client consultation, construction monitoring, and testing will be performed during the final design and construction phases to verify compliance with these recommendations. Maintaining Southern California Geotechnical, Inc., (SCG) as the geotechnical consultant from the beginning to the end of the project will provide continuity of services. The geotechnical engineering firm providing testing and observation services shall assume the responsibility of Geotechnical Engineer of Record. The Grading Guide Specifications, included as Appendix D, should be considered part of this report, and should be incorporated into the project specifications. The contractor and/or owner of the development should bring to the attention of the geotechnical engineer any conditions that differ from those stated in this report, or which may be detrimental for the development. 6.1 Seismic Design Considerations The subject site is located in an area which is subject to strong ground motions due to earthquakes. The performance of a site specific seismic hazards analysis was beyond the scope of this investigation. However, numerous faults capable of producing significant ground motions are located near the subject site. Due to economic considerations, it is not generally considered reasonable to design a structure that is not susceptible to earthquake damage. Therefore, significant damage to structures may be unavoidable during large earthquakes. The proposed structures should, however, be designed to resist structural collapse and thereby provide reasonable protection from serious injury, catastrophic property damage and loss of life. Faulting and Seismicity Research of available maps indicates that the subject site is not located within an Alquist-Priolo Earthquake Fault Zone. Furthermore, SCG did not identify any evidence of faulting during the geotechnical investigation. Therefore, the possibility of significant fault rupture on the site is considered to be low. The potential for other geologic hazards such as seismically induced settlement, lateral spreading, tsunamis, inundation, seiches, flooding, and subsidence affecting the site is considered low. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 10 Seismic Design Parameters The 2019 California Building Code (CBC) provides procedures for earthquake resistant structural design that include considerations for on-site soil conditions, occupancy, and the configuration of the structure including the structural system and height. The seismic design parameters presented below are based on the soil profile and the proximity of known faults with respect to the subject site. Based on standards in place at the time of this report, the proposed development is expected to be designed in accordance with the requirements of the 2019 edition of the California Building Code (CBC), which was adopted on January 1, 2020. The 2019 CBC Seismic Design Parameters have been generated using the SEAOC/OSHPD Seismic Design Maps Tool, a web-based software application available at the website www.seismicmaps.org. This software application calculates seismic design parameters in accordance with several building code reference documents, including ASCE 7-16, upon which the 2019 CBC is based. The application utilizes a database of risk-targeted maximum considered earthquake (MCER) site accelerations at 0.01-degree intervals for each of the code documents. The tables below were created using data obtained from the application. The output generated from this program is included as Plate E-1 in Appendix E of this report. The 2019 CBC requires that a site-specific ground motion study be performed in accordance with Section 11.4.8 of ASCE 7-16 for Site Class D sites with a mapped S1 value greater than 0.2. However, Section 11.4.8 of ASCE 7-16 also indicates an exception to the requirement for a site- specific ground motion hazard analysis for certain structures on Site Class D sites. The commentary for Section 11 of ASCE 7-16 (Page 534 of Section C11 of ASCE 7-16) indicates that “In general, this exception effectively limits the requirements for site-specific hazard analysis to very tall and or flexible structures at Site Class D sites.” Based on our understanding of the proposed development, the seismic design parameters presented below were calculated assuming that the exception in Section 11.4.8 applies to the proposed structure at this site. However, the structural engineer should verify that this exception is applicable to the proposed structure. Based on the exception, the spectral response accelerations presented below were calculated using the site coefficients (Fa and Fv) from Tables 1613.2.3(1) and 1613.2.3(2) presented in Section 16.4.4 of the 2019 CBC. 2019 CBC SEISMIC DESIGN PARAMETERS Parameter Value Mapped Spectral Acceleration at 0.2 sec Period SS 1.979 Mapped Spectral Acceleration at 1.0 sec Period S1 0.745 Site Class --- D Site Modified Spectral Acceleration at 0.2 sec Period SMS 1.979 Site Modified Spectral Acceleration at 1.0 sec Period SM1 1.267 Design Spectral Acceleration at 0.2 sec Period SDS 1.319 Design Spectral Acceleration at 1.0 sec Period SD1 0.844 Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 11 It should be noted that the site coefficient Fv and the parameters SM1 and SD1 were not included in the SEAOC/OSHPD Seismic Design Maps Tool output for the 2019 CBC. We calculated these parameters-based on Table 1613.2.3(2) in Section 16.4.4 of the 2019 CBC using the value of S1 obtained from the Seismic Design Maps Tool, assuming that a site-specific ground motion hazards analysis is not required for the proposed building at this site. Liquefaction Liquefaction is the loss of strength in generally cohesionless, saturated soils when the pore- water pressure induced in the soil by a seismic event becomes equal to or exceeds the overburden pressure. The primary factors which influence the potential for liquefaction include groundwater table elevation, soil type and grain size characteristics, relative density of the soil, initial confining pressure, and intensity and duration of ground shaking. The depth within which the occurrence of liquefaction may impact surface improvements is generally identified as the upper 50 feet below the existing ground surface. Liquefaction potential is greater in saturated, loose, poorly graded fine sands with a mean (d50) grain size in the range of 0.075 to 0.2 mm (Seed and Idriss, 1971). Clayey (cohesive) soils or soils which possess clay particles (d<0.005mm) in excess of 20 percent (Seed and Idriss, 1982) are generally not considered to be susceptible to liquefaction, nor are those soils which are above the historic static groundwater table. The California Geological Survey (CGS) has not yet conducted detailed seismic hazards mapping in the area of the subject site. The general liquefaction susceptibility of the site was determined by research of the San Bernardino County Land Use Plan, General Plan, Geologic Hazard Overlays. Map FH29 indicates that the subject site is not located within an area of liquefaction susceptibility. Based on the mapping performed by the county of San Bernardino and the subsurface conditions encountered at the boring locations, liquefaction is not considered to be a design concern for this project. 6.2 Geotechnical Design Considerations General Based on the subsurface condition encountered at the boring locations, the subject site is underlain by native alluvial soils, extending to the maximum depth explored of 25± feet below the existing site grades. The near-surface alluvium encountered at the boring locations consists of medium dense to dense silty fine sands and silty fine to coarse sands with varying cobble content. The near-surface native alluvial soils possess moisture contents well below the optimum moisture content for compaction. The results of laboratory testing indicate that the near-surface soils encountered at Boring No. B-5 are compressible when loaded and may be subject to hydrocollapse when inundated with water to depths of 3 to 4± feet below the existing site grades. Based on these conditions, the near-surface alluvial soils, in their present condition, are not considered suitable to support the foundation loads of the new building. At greater depths, the underlying alluvial soils generally consist of high strength, medium dense to very dense fine to coarse sands and gravelly fine to coarse sands with little fine to coarse gravel and occasional to abuntant cobbles. Based on these conditions, remedial grading is considered Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 12 warranted within the proposed building area in order to remove a portion of the near-surface native alluvial soils. Settlement The recommended remedial grading will remove the existing undocumented fill soils and a portion of the upper native alluvial soils and replace these materials as compacted structural fill. The native soils that will remain in place below the recommended depth of overexcavation will not be subject to large stress increases from the foundations of the new structure. Therefore, following completion of the recommended grading, post-construction settlements are expected to be within tolerable limits. Expansion The near-surface soils consist of gravelly sands, sands, and silty sands with no appreciable clay content. These materials have been visually classified as non-expansive. Therefore, no design considerations related to expansive soils are considered warranted for this site. Soluble Sulfates The results of the soluble sulfate testing indicated that the selected sample of the near-surface soils possesses a sulfate concentration of approximately 0.002 percent. This concentration is considered to be “not applicable” (S0) with respect to the American Concrete Institute (ACI) Publication 318-14 Building Code Requirements for Structural Concrete and Commentary, Section 4.3. Therefore, specialized concrete mix designs are not considered to be necessary, with regard to sulfate protection purposes. It is, however, recommended that additional soluble sulfate testing be conducted at the completion of rough grading to verify the soluble sulfate concentrations of the soils which are present at pad grade within the building area. Corrosion Potential The results of laboratory testing indicate that the on-site soils possess a saturated resistivity value of 10,000 ohm-cm, and a pH value of 7.0. The test results have been evaluated in accordance with guidelines published by the Ductile Iron Pipe Research Association (DIPRA). The DIPRA guidelines consist of a point system by which characteristics of the soils are used to quantify the corrosivity characteristics of the site. Sulfides and redox potential are factors that are also used in the evaluation procedure. We have evaluated the corrosivity characteristics of the on-site soils using resistivity, pH, and moisture content. Based on these factors, and utilizing the DIPRA procedure, the on-site soils are not considered to be corrosive to ductile iron pipe. Therefore, polyethylene protection is not expected to be required for cast iron or ductile iron pipes. The results of laboratory testing indicate that the on-site soils possess a non-detectable level of chlorides concentration. In general, soils possessing chloride concentrations in excess of 500 parts per million (ppm) are considered to be corrosive with respect to steel reinforcement within reinforced concrete. Based on the lack of any significant chlorides in the tested sample, the site is considered to have a C1 chloride exposure in accordance with the American Concrete Institute (ACI) Publication 318 Building Code Requirements for Structural Concrete and Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 13 Commentary. Therefore, a specialized concrete mix design for reinforced concrete for protection against chloride exposure is not considered warranted. Nitrates present in soil can be corrosive to copper tubing at concentrations greater than 50 mg/kg. The tested sample possesses a nitrate concentration of 23 mg/kg. Based on this test result, the on-site soils are not considered to be corrosive to copper pipe. Since SCG does not practice in the area of corrosion engineering, we recommend that the client contact a corrosion engineer to provide a more thorough evaluation. Shrinkage/Subsidence Removal and recompaction of the existing fill soils and near-surface alluvium is estimated to result in an average shrinkage of 0 to 10 percent. It should be noted that the potential shrinkage estimate is based on our experience with similar projects at nearby sites. It was not practical to obtain undisturbed samples based on the gravel, cobble, and boulder content of the onsite soils. Therefore, the actual amount of shrinkage could vary considerably from these estimates. If a more accurate and precise shrinkage estimate is desired, SCG can perform a shrinkage study involving several excavated test-pits where in-place densities are determined using in-situ testing methods. Please contact SCG for details and a cost estimate regarding a shrinkage study, if desired. Minor ground subsidence is expected to occur in the soils below the zone of removal, due to settlement and machinery working. The subsidence is estimated to be 0.1 feet. These estimates are based on previous experience and the subsurface conditions encountered at the boring locations. The actual amount of subsidence is expected to be variable and will be dependent on the type of machinery used, repetitions of use, and dynamic effects, all of which are difficult to assess precisely. Grading and Foundation Plan Review No grading or foundation plans were available at the time of this report. It is therefore recommended that we be provided with copies of the preliminary plans, when they become available, for review with regard to the conclusions, recommendations, and assumptions contained within this report. 6.3 Site Grading Recommendations The grading recommendations presented below are based on the subsurface conditions encountered at the boring locations and our understanding of the proposed development. We recommend that all grading activities be completed in accordance with the Grading Guide Specifications included as Appendix D of this report, unless superseded by site-specific recommendations presented below. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 14 Site Stripping Initial site preparation should include stripping of any surficial vegetation from the site. This should include any weeds, grasses, and shrubs. The actual extent of site stripping should be determined in the field by the geotechnical engineer, based on the organic content and stability of the materials encountered. Treatment of Existing Soils: Building Pad Remedial grading will be necessary within the proposed building pad area to remove a portion of the variable strength native alluvium. At a minimum, the overexcavation is recommended to extend to a depth of at least 5 feet below existing grade and 3 feet below proposed building pad subgrade elevation, whichever is greater. Within the influence zones of the new foundations, the overexcavation should extend to a depth of at least 3 feet below proposed foundation bearing grade. The overexcavation areas should extend at least 5 feet beyond the building perimeters, and to an extent equal to the depth of fill below the new foundations. If the proposed structure incorporates any exterior columns (such as for a canopy or overhang) the area of overexcavation should also encompass these areas. Following completion of the overexcavation, the subgrade soils within the building area should be evaluated by the geotechnical engineer to verify their suitability to serve as the structural fill subgrade, as well as to support the foundation loads of the new structure. This evaluation should include proofrolling and probing to identify any soft, loose or otherwise unstable soils that must be removed. Some localized areas of deeper excavation may be required if loose, porous, or low density native soils are encountered at the base of the overexcavation. After a suitable overexcavation subgrade has been achieved, the exposed soils should be scarified to a depth of at least 12 inches thoroughly flooded to achieve a moisture content of 0 to 4 percent above optimum moisture content to a depth of at least 24 inches. The subgrade soils should then be recompacted to at least 90 percent of the ASTM D-1557 maximum dry density. All structural fill soils present within the proposed building area should be compacted to at least 90 percent of the ASTM D-1557 maximum dry density. Treatment of Existing Soils: Retaining Walls and Site Walls The existing soils within the areas of any proposed retaining walls and site walls should be overexcavated to a depth of 2 feet below foundation bearing grade and replaced as compacted structural fill as discussed above for the proposed building pad. Any undocumented fill soils or disturbed native alluvium within any of these foundation areas should be removed in their entirety. Any erection pads used to construct the walls are considered to be part of the foundation system with respect to these remedial grading recommendations. The overexcavation subgrade soils should be evaluated by the geotechnical engineer prior to scarifying, moisture conditioning, and recompacting the upper 12 inches of exposed subgrade soils, as discussed for the building area. The previously excavated soils may then be replaced as compacted structural fill. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 15 If the recommended remedial grading cannot be completed for screen walls located along property lines, such walls should be designed for a reduced allowable bearing pressure. The allowable bearing pressure will be determined based on the actual extent of remedial grading that can be accomplished. Treatment of Existing Soils: Flatwork, Parking and Drive Areas Based on economic considerations, removal and replacement of the variable strength existing fill and alluvial soils is not considered warranted within the proposed flatwork, parking, and drive areas. Subgrade preparation in the new parking and drive areas should initially consist of removal of all soils disturbed during stripping and demolition operations. The geotechnical engineer should then evaluate the subgrade to identify any areas of additional unsuitable soils. The subgrade soils should then be scarified to a depth of 12± inches, moisture conditioned to 0 to 4 percent above optimum moisture content (to a depth of at least 24 inches) and recompacted to at least 90 percent of the ASTM D-1557 maximum dry density. Based on the presence of variable strength surficial soils throughout the site, it is expected that some isolated areas of additional overexcavation may be required to remove zones of lower strength, unsuitable soils. The grading recommendations presented above for the proposed flatwork, parking, and drive areas assume that the owner and/or developer can tolerate minor amounts of settlement within the proposed parking areas. The grading recommendations presented above do not completely mitigate the extent of undocumented fill soils variable density alluvium in the parking areas. As such, settlement and associated pavement distress could occur. Typically, repair of such distressed areas involves significantly lower costs than completely mitigating these soils at the time of construction. If the owner cannot tolerate the risk of such settlements, the flatwork, parking and drive areas should be overexcavated to a depth of 2 feet below proposed pavement subgrade elevation, with the resulting soils replaced as compacted structural fill. Fill Placement • Fill soils should be placed in thin (6 inches), near-horizontal lifts, moisture conditioned to 0 to 4 percent above the optimum moisture content, and compacted. • On-site soils may be used for fill provided they are cleaned of any debris to the satisfaction of the geotechnical engineer. • All grading and fill placement activities should be completed in accordance with the requirements of the 2019 CBC and the grading code of the city of Fontana and/or the county of San Bernardino. • All fill soils should be compacted to at least 90 percent of the ASTM D-1557 maximum dry density. • Compaction tests should be performed periodically by the geotechnical engineer as random verification of compaction and moisture content. These tests are intended to aid the contractor. Since the tests are taken at discrete locations and depths, they may not be indicative of the entire fill and therefore should not relieve the contractor of his responsibility to meet the job specifications. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 16 Imported Structural Fill All imported structural fill should consist of very low expansive (EI < 20), well graded soils possessing at least 10 percent fines (that portion of the sample passing the No. 200 sieve). Additional specifications for structural fill are presented in the Grading Guide Specifications, included as Appendix D. Utility Trench Backfill In general, all utility trench backfill should be compacted to at least 90 percent of the ASTM D- 1557 maximum dry density. As an alternative, a clean sand (minimum Sand Equivalent of 30) may be placed within trenches and compacted in place (jetting or flooding is not recommended). It is recommended that materials in excess of 3 inches in size not be used for utility trench backfill. Compacted trench backfill should conform to the requirements of the local grading code, and more restrictive requirements may be indicated by the city of Fontana and/or the county of San Bernardino. All utility trench backfills should be witnessed by the geotechnical engineer. The trench backfill soils should be compaction tested where possible; probed and visually evaluated elsewhere. Utility trenches which parallel a footing, and extending below a 1h:1v plane projected from the outside edge of the footing should be backfilled with structural fill soils, compacted to at least 90 percent of the ASTM D-1557 standard. Pea gravel backfill should not be used for these trenches. Any soils used to backfill voids around subsurface utility structures, such as manholes or vaults, should be placed as compacted structural fill. If it is not practical to place compacted fill in these areas, then such void spaces may be backfilled with lean concrete slurry. Uncompacted pea gravel or sand is not recommended for backfilling these voids since these materials have a potential to settle and thereby cause distress of pavements placed around these subterranean structures. 6.4 Construction Considerations Excavation Considerations The near-surface soils are predominately granular in nature. These materials will likely be subject to caving within shallow excavations. Where caving occurs within shallow excavations, flattened excavation slopes may be sufficient to provide excavation stability. On a preliminary basis, the inclination of temporary slopes should not exceed 2h:1v. Maintaining adequate moisture content within the near-surface soils will improve excavation stability. All excavation activities on this site should be conducted in accordance with Cal-OSHA regulations. Moisture Sensitive Subgrade Soils Based on their granular composition, the on-site soils are susceptible to erosion. The site should, therefore, be graded to prevent ponding of surface water and to prevent water from running into excavations. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 17 Groundwater The static groundwater table at this site is considered to exist at a depth of more than 25 feet. Therefore, groundwater is not expected to impact the grading or foundation construction activities. 6.5 Foundation Design and Construction Based on the preceding grading recommendations, it is assumed that the new building pad will be underlain by structural fill soils used to replace existing near-surface alluvial soils. These new structural fill soils are expected to extend to depths of at least 3 feet below proposed foundation bearing grade. Based on this subsurface profile, the proposed structure may be supported on conventional shallow foundations. Foundation Design Parameters New square and rectangular footings may be designed as follows: • Maximum, net allowable soil bearing pressure: 2,500 lbs/ft2. • Minimum wall/column footing width: 14 inches/24 inches. • Minimum longitudinal steel reinforcement within strip footings: Two (2) No. 5 rebars (1 top and 1 bottom). • Minimum foundation embedment: 12 inches into suitable structural fill soils, and at least 18 inches below adjacent exterior grade. Interior column footings may be placed immediately beneath the floor slab. • It is recommended that the perimeter building foundations be continuous across all exterior doorways. Any flatwork adjacent to the exterior doors should be doweled into the perimeter foundations in a manner determined by the structural engineer. The allowable bearing pressure presented above may be increased by one-third when considering short duration wind or seismic loads. The minimum steel reinforcement recommended above is based on geotechnical considerations; additional reinforcement may be necessary for structural considerations. The actual design of the foundations should be determined by the structural engineer. Foundation Construction The foundation subgrade soils should be evaluated at the time of overexcavation, as discussed in Section 6.3 of this report. It is further recommended that the foundation subgrade soils be evaluated by the geotechnical engineer immediately prior to steel or concrete placement. Soils suitable for direct foundation support should consist of newly placed structural fill, compacted to at least 90 percent of the ASTM D-1557 maximum dry density. Any unsuitable materials should be removed to a depth of suitable bearing compacted structural fill, with the resulting Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 18 excavations backfilled with compacted fill soils. As an alternative, lean concrete slurry (500 to 1,500 psi) may be used to backfill such isolated overexcavations. The foundation subgrade soils should also be properly moisture conditioned to 0 to 4 percent above the Modified Proctor optimum, to a depth of at least 12 inches below bearing grade. Since it is typically not feasible to increase the moisture content of the floor slab and foundation subgrade soils once rough grading has been completed, care should be taken to maintain the moisture content of the building pad subgrade soils throughout the construction process. Estimated Foundation Settlements Post-construction total and differential settlements of shallow foundations designed and constructed in accordance with the previously presented recommendations are estimated to be less than 1.0 and 0.5 inches, respectively. Differential movements are expected to occur over a 30-foot span, thereby resulting in an angular distortion of less than 0.002 inches per inch. Lateral Load Resistance Lateral load resistance will be developed by a combination of friction acting at the base of foundations and slabs and the passive earth pressure developed by footings below grade. The following friction and passive pressure may be used to resist lateral forces: • Passive Earth Pressure: 300 lbs/ft3 • Friction Coefficient: 0.30 These are allowable values, and include a factor of safety. When combining friction and passive resistance, the passive pressure component should be reduced by one-third. These values assume that footings will be poured directly against compacted structural fill. The maximum allowable passive pressure is 3,000 lbs/ft2. 6.6 Floor Slab Design and Construction Subgrades which will support new floor slab should be prepared in accordance with the recommendations contained in the Site Grading Recommendations section of this report. Based on the anticipated grading which will occur at this site, the floor of the new structure may be constructed as a conventional slab-on-grade supported on newly placed structural fill soils. These fill soils are expected to extend to a depth of at least 3 feet below finished pad grade. Based on geotechnical considerations, the floor slab may be designed as follows: • Minimum slab thickness: 6 inches. • Minimum slab reinforcement: Reinforcement is not expected to be required for geotechnical conditions. The actual floor slab reinforcement should be determined by the structural engineer, based upon the imposed loading. • Modulus of subgrade reaction, k =150 psi/in Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 19 • Slab underlayment: If moisture sensitive floor coverings will be used the minimum slab underlayment should consist of a moisture vapor barrier constructed below the entire area of the proposed slab. The moisture vapor barrier should meet or exceed the Class A rating as defined by ASTM E 1745-97 and have a permeance rating less than 0.01 perms as described in ASTM E 96-95 and ASTM E 154-88. A polyolefin material such as Stego® Wrap Vapor Barrier or equivalent will meet these specifications. The moisture vapor barrier should be properly constructed in accordance with all applicable manufacturer specifications. Given that a rock free subgrade is anticipated and that a capillary break is not required, sand below the barrier is not required. The need for sand and/or the amount of sand above the moisture vapor barrier should be specified by the structural engineer or concrete contractor. The selection of sand above the barrier is not a geotechnical engineering issue and hence outside our purview. Where moisture sensitive floor coverings are not anticipated, the vapor barrier may be eliminated. • Moisture condition the floor slab subgrade soils to 0 to 4 percent above the Modified Proctor optimum moisture content, to a depth of 12 inches. The moisture content of the floor slab subgrade soils should be verified by the geotechnical engineer within 24 hours prior to concrete placement. • Proper concrete curing techniques should be utilized to reduce the potential for slab curling or the formation of excessive shrinkage cracks. The actual design of the floor slab should be completed by the structural engineer to verify adequate thickness and reinforcement. 6.7 Retaining Wall Design and Construction Small retaining walls are expected to be necessary in the truck dock areas and may also be required to facilitate the new site grades. The parameters recommended for use in the design of these walls are presented below. Retaining Wall Design Parameters Based on the soil conditions encountered at the boring locations, the following parameters may be used in the design of new retaining walls for this site. We have provided parameters assuming the use of on-site soils for retaining wall backfill. The on-site soils generally consist of sands, silty sands, and gravelly sands. Based on their classification, these materials are expected to possess a friction angle of at least 32 degrees when compacted to at least 90 percent of the ASTM D-1557 maximum dry density. If desired, SCG could provide design parameters for an alternative select backfill material behind the retaining walls. The use of select backfill material could result in lower lateral earth pressures. In order to use the design parameters for the imported select fill, this material must be placed within the entire active failure wedge. This wedge is defined as extending from the heel of the retaining wall upwards at an angle of approximately 60° from horizontal. If select backfill material behind the retaining wall is desired, SCG should be contacted for supplementary recommendations. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 20 RETAINING WALL DESIGN PARAMETERS Design Parameter Soil Type On-site Sands and Silty Sands Internal Friction Angle () 32 Unit Weight 130 lbs/ft3 Equivalent Fluid Pressure: Active Condition (level backfill) 40 lbs/ft3 Active Condition (2h:1v backfill) 62 lbs/ft3 At-Rest Condition (level backfill) 62 lbs/ft3 The walls should be designed using a soil-footing coefficient of friction of 0.30 and an equivalent passive pressure of 300 lbs/ft3. The structural engineer should incorporate appropriate factors of safety in the design of the retaining walls. The active earth pressure may be used for the design of retaining walls that do not directly support structures or support soils that in turn support structures and which will be allowed to deflect. The at-rest earth pressure should be used for walls that will not be allowed to deflect such as those which will support foundation bearing soils, or which will support foundation loads directly. Where the soils on the toe side of the retaining wall are not covered by a "hard" surface such as a structure or pavement, the upper 1 foot of soil should be neglected when calculating passive resistance due to the potential for the material to become disturbed or degraded during the life of the structure. Retaining Wall Foundation Design The retaining wall foundations should be underlain by at least 2 feet of newly placed structural fill. Foundations to support new retaining walls should be designed in accordance with the general Foundation Design Parameters presented in a previous section of this report. Seismic Lateral Earth Pressures In accordance with the 2019 CBC, any retaining walls more than 6 feet in height must be designed for seismic lateral earth pressures. If walls 6 feet or more are required for this site, the geotechnical engineer should be contacted for supplementary seismic lateral earth pressure recommendations. Backfill Material On-site soils may be used to backfill the retaining walls. However, all backfill material placed within 3 feet of the back-wall face should have a particle size no greater than 3 inches. The retaining wall backfill materials should be well graded. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 21 It is recommended that a minimum 1 foot thick layer of free-draining granular material (less than 5 percent passing the No. 200 sieve) be placed against the face of the retaining walls. This material should extend from the top of the retaining wall footing to within 1 foot of the ground surface on the back side of the retaining wall. This material should be approved by the geotechnical engineer. In lieu of the 1 foot thick layer of free-draining material, a properly installed prefabricated drainage composite such as the MiraDRAIN 6000XL (or approved equivalent), which is specifically designed for use behind retaining walls, may be used. If the layer of free-draining material is not covered by an impermeable surface, such as a structure or pavement, a 12-inch thick layer of a low permeability soil should be placed over the backfill to reduce surface water migration to the underlying soils. The layer of free draining granular material should be separated from the backfill soils by a suitable geotextile, approved by the geotechnical engineer All retaining wall backfill should be placed and compacted under engineering-controlled conditions in the necessary layer thicknesses to ensure an in-place density between 90 and 93 percent of the maximum dry density as determined by the Modified Proctor test (ASTM D1557- 91). Care should be taken to avoid over-compaction of the soils behind the retaining walls, and the use of heavy compaction equipment should be avoided. Subsurface Drainage As previously indicated, the retaining wall design parameters are based upon drained backfill conditions. Consequently, some form of permanent drainage system will be necessary in conjunction with the appropriate backfill material. Subsurface drainage may consist of either: • A weep hole drainage system typically consisting of a series of 2-inch diameter holes in the wall situated slightly above the ground surface elevation on the exposed side of the wall and at an approximate 10-foot on-center spacing. Alternatively, 4-inch diameter holes at an approximate 20-foot on-center spacing can be used for this type of drainage system. In addition, the weep holes should include a 2 cubic foot pocket of open graded gravel, surrounded by an approved geotextile fabric, at each weep hole location. • A 4-inch diameter perforated pipe surrounded by 2 cubic feet of gravel per linear foot of drain placed behind the wall, above the retaining wall footing. The gravel layer should be wrapped in a suitable geotextile fabric to reduce the potential for migration of fines. The footing drain should be extended to daylight or tied into a storm drainage system. The actual design of this type of system should be determined by the civil engineer to verify that the drainage system possesses the adequate capacity and slope for its intended use. 6.8 Pavement Design Parameters Site preparation in the pavement area should be completed as previously recommended in the Site Grading Recommendations section of this report. The subsequent pavement recommendations assume proper drainage and construction monitoring, and are based on either PCA or CALTRANS design parameters for a twenty (20) year design period. However, these designs also assume a routine pavement maintenance program to obtain the anticipated 20-year pavement service life. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 22 Pavement Subgrades It is anticipated that the new pavements will be supported on the newly-placed engineered fill soils and/or native soils that have been scarified, moisture conditioned, and recompacted. These materials generally consist of sands and silty sands. These materials are expected to exhibit good to very good pavement support characteristics. Based on the R-value testing performed as part of our scope for this project and the variability of the on-site soils, the subsequent pavement designs are based upon an R-value of 50. Any fill material imported to the site should have support characteristics equal to or greater than that of the on-site soils and be placed and compacted under engineering-controlled conditions. It may be desirable to perform R-value testing after the completion of rough grading to verify the R-value of the as- graded parking subgrade. Asphaltic Concrete Presented below are the recommended thicknesses for new flexible pavement structures consisting of asphaltic concrete over a granular base. An alternate pavement section has been provided for use in parking stall areas due to the anticipated lower traffic intensity in these areas. However, truck traffic must be excluded from areas where the thinner pavement section is used; otherwise premature pavement distress may occur. The pavement designs are based on the traffic indices (TI’s) indicated. The client and/or civil engineer should verify that these TI’s are representative of the anticipated traffic volumes. Traffic Index No. of Heavy Trucks per Day 4.0 0 5.0 1 6.0 3 7.0 11 8.0 35 9.0 93 For the purpose of the traffic volumes indicated above, a truck is defined as a 5-axle tractor trailer unit with one 8-kip axle and two 32-kip tandem axles. All of the traffic indices allow for 1,000 automobiles per day. ASPHALT PAVEMENTS (R=50) Materials Thickness (inches) Auto Parking and Auto Drive Lanes (TI = 4.0 to 5.0) Truck Traffic TI = 6.0 TI = 7.0 TI = 8.0 TI = 9.0 Asphalt Concrete 3 3½ 4 5 5½ Aggregate Base 3 4 5 5 7 Compacted Subgrade 12 12 12 12 12 Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 23 The aggregate base course should be compacted to at least 95 percent of the ASTM D-1557 maximum dry density. The asphaltic concrete should be compacted to at least 95 percent of the Marshall maximum density, as determined by ASTM D-2726. The aggregate base course may consist of crushed aggregate base (CAB) or crushed miscellaneous base (CMB), which is a recycled gravel, asphalt and concrete material. The gradation, R-Value, Sand Equivalent, and Percentage Wear of the CAB or CMB should comply with appropriate specifications contained in the current edition of the “Greenbook” Standard Specifications for Public Works Construction. Portland Cement Concrete The preparation of the subgrade soils within Portland cement concrete pavement areas should be performed as previously described in Section 6.3 “Treatment of Existing Soils: Flatwork, Parking, and Drive Areas”. The minimum recommended thicknesses for the Portland Cement Concrete pavement sections are as follows: PORTLAND CEMENT CONCRETE PAVEMENTS (R=50) Materials Thickness (inches) Autos and Light Truck Traffic (TI = 6.0) Truck Traffic TI = 7.0 TI = 8.0 TI = 9.0 PCC 5 5½ 6½ 8 Compacted Subgrade (95% minimum compaction) 12 12 12 12 The concrete should have a 28-day compressive strength of at least 3,000 psi. Reinforcing within all pavements should be designed by the structural engineer. The maximum joint spacing within all of the PCC pavements is recommended to be equal to or less than 30 times the pavement thickness. The actual joint spacing and reinforcing of the Portland cement concrete pavements should be determined by the structural engineer. Proposed Warehouse – Fontana, CA Project No. 21G260-1 Page 24 7.0 GENERAL COMMENTS This report has been prepared as an instrument of service for use by the client, in order to aid in the evaluation of this property and to assist the architects and engineers in the design and preparation of the project plans and specifications. This report may be provided to the contractor(s) and other design consultants to disclose information relative to the project. However, this report is not intended to be utilized as a specification in and of itself, without appropriate interpretation by the project architect, civil engineer, and/or structural engineer. The reproduction and distribution of this report must be authorized by the client and Southern California Geotechnical, Inc. Furthermore, any reliance on this report by an unauthorized third party is at such party’s sole risk, and we accept no responsibility for damage or loss which may occur. The client(s)’ reliance upon this report is subject to the Engineering Services Agreement, incorporated into our proposal for this project. The analysis of this site was based on a subsurface profile interpolated from limited discrete soil samples. While the materials encountered in the project area are considered to be representative of the total area, some variations should be expected between boring locations and sample depths. If the conditions encountered during construction vary significantly from those detailed herein, we should be contacted immediately to determine if the conditions alter the recommendations contained herein. This report has been based on assumed or provided characteristics of the proposed development. It is recommended that the owner, client, architect, structural engineer, and civil engineer carefully review these assumptions to ensure that they are consistent with the characteristics of the proposed development. If discrepancies exist, they should be brought to our attention to verify that they do not affect the conclusions and recommendations contained herein. We also recommend that the project plans and specifications be submitted to our office for review to verify that our recommendations have been correctly interpreted. The analysis, conclusions, and recommendations contained within this report have been promulgated in accordance with generally accepted professional geotechnical engineering practice. No other warranty is implied or expressed. S I T E PROPOSED WAREHOUSE SCALE: 1" = 2000' DRAWN: MD CHKD: RGT SCG PROJECT 21G260-1 PLATE 1 SITE LOCATION MAP FONTANA, CALIFORNIA SOURCE: USGS TOPOGRAPHIC MAP OF THE FONTANA QUADRANGLE, SAN BERNARDINO COUNTY, CALIFORNIA, 2018. B-1 B-2 B-4 B-5 B-6 B-7 FU T U R E B E E C H A V E N U E B-3 PROPERTY LINE SCALE: 1" = 80' DRAWN: MD CHKD: RGT PLATE 2 SCG PROJECT 21G260-1 FONTANA, CALIFORNIA PROPOSED WAREHOUSE BORING LOCATION PLAN NO R T H So C a l G e o APPROXIMATE BORING LOCATION GEOTECHNICAL LEGEND NOTE: SITE PLAN PREPARED BY HPA ARCHITECTURE. AERIAL PHOTO OBTAINED FROM GOOGLE EARTH. BORING LOG LEGEND SAMPLE TYPE GRAPHICAL SYMBOL SAMPLE DESCRIPTION AUGER SAMPLE COLLECTED FROM AUGER CUTTINGS, NO FIELD MEASUREMENT OF SOIL STRENGTH. (DISTURBED) CORE ROCK CORE SAMPLE: TYPICALLY TAKEN WITH A DIAMOND-TIPPED CORE BARREL. TYPICALLY USED ONLY IN HIGHLY CONSOLIDATED BEDROCK. GRAB 1 SOIL SAMPLE TAKEN WITH NO SPECIALIZED EQUIPMENT, SUCH AS FROM A STOCKPILE OR THE GROUND SURFACE. (DISTURBED) CS CALIFORNIA SAMPLER: 2-1/2 INCH I.D. SPLIT BARREL SAMPLER, LINED WITH 1-INCH HIGH BRASS RINGS. DRIVEN WITH SPT HAMMER. (RELATIVELY UNDISTURBED) NSR NO RECOVERY: THE SAMPLING ATTEMPT DID NOT RESULT IN RECOVERY OF ANY SIGNIFICANT SOIL OR ROCK MATERIAL. SPT STANDARD PENETRATION TEST: SAMPLER IS A 1.4 INCH INSIDE DIAMETER SPLIT BARREL, DRIVEN 18 INCHES WITH THE SPT HAMMER. (DISTURBED) SH SHELBY TUBE: TAKEN WITH A THIN WALL SAMPLE TUBE, PUSHED INTO THE SOIL AND THEN EXTRACTED. (UNDISTURBED) VANE VANE SHEAR TEST: SOIL STRENGTH OBTAINED USING A 4 BLADED SHEAR DEVICE. TYPICALLY USED IN SOFT CLAYS-NO SAMPLE RECOVERED. COLUMN DESCRIPTIONS DEPTH: Distance in feet below the ground surface. SAMPLE: Sample Type as depicted above. BLOW COUNT: Number of blows required to advance the sampler 12 inches using a 140 lb hammer with a 30-inch drop. 50/3” indicates penetration refusal (>50 blows) at 3 inches. WH indicates that the weight of the hammer was sufficient to push the sampler 6 inches or more. POCKET PEN.: Approximate shear strength of a cohesive soil sample as measured by pocket penetrometer. GRAPHIC LOG: Graphic Soil Symbol as depicted on the following page. DRY DENSITY: Dry density of an undisturbed or relatively undisturbed sample in lbs/ft3. MOISTURE CONTENT: Moisture content of a soil sample, expressed as a percentage of the dry weight. LIQUID LIMIT: The moisture content above which a soil behaves as a liquid. PLASTIC LIMIT: The moisture content above which a soil behaves as a plastic. PASSING #200 SIEVE: The percentage of the sample finer than the #200 standard sieve. UNCONFINED SHEAR: The shear strength of a cohesive soil sample, as measured in the unconfined state. SM SP COARSE GRAINEDSOILS SW TYPICAL DESCRIPTIONS WELL-GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLE OR NOFINES SILTY GRAVELS, GRAVEL - SAND - SILT MIXTURES LETTERGRAPH POORLY-GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLEOR NO FINES GC GM GP GW POORLY-GRADED SANDS, GRAVELLY SAND, LITTLE OR NOFINES SILTSAND CLAYS MORE THAN 50% OF MATERIAL ISLARGER THANNO. 200 SIEVE SIZE MORE THAN 50%OF MATERIAL IS SMALLER THANNO. 200 SIEVESIZE MORE THAN 50%OF COARSEFRACTION PASSING ON NO.4 SIEVE MORE THAN 50%OF COARSE FRACTIONRETAINED ON NO.4 SIEVE CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES FINEGRAINED SOILS SYMBOLSMAJOR DIVISIONS SOIL CLASSIFICATION CHART PT OH CH MH OL CL ML CLEAN SANDS SC SILTY SANDS, SAND - SILTMIXTURES CLAYEY SANDS, SAND - CLAY MIXTURES INORGANIC SILTS AND VERY FINESANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEYSILTS WITH SLIGHT PLASTICITY INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS ORGANIC SILTS AND ORGANICSILTY CLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND ORSILTY SOILS INORGANIC CLAYS OF HIGH PLASTICITY ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS PEAT, HUMUS, SWAMP SOILS WITHHIGH ORGANIC CONTENTS SILTS AND CLAYS GRAVELS WITH FINES SAND AND SANDY SOILS (LITTLE OR NO FINES) SANDS WITH FINES LIQUID LIMITLESS THAN 50 LIQUID LIMIT GREATER THAN 50 HIGHLY ORGANIC SOILS NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS GRAVEL AND GRAVELLYSOILS (APPRECIABLE AMOUNT OF FINES) (APPRECIABLE AMOUNT OF FINES) (LITTLE OR NO FINES) WELL-GRADED SANDS, GRAVELLYSANDS, LITTLE OR NO FINES CLEAN GRAVELS ALLUVIUM: Gray Brown Silty fine to coarse Sand, occasional toabundant Cobbles, dense-dry Gray Brown fine to coarse Sand, little fine to coarse Gravel, occasional to abundant Cobbles, dense to very dense-dry to damp Boring Terminated at 25' Disturbed Sample 61 56 46 77/11" 54 42 43 50/5" 118 120 127 1 2 2 2 1 2 2 5 10 15 20 25 LABORATORY RESULTS CO M M E N T S TEST BORING LOG PA S S I N G #2 0 0 S I E V E ( % ) BL O W C O U N T DESCRIPTION SURFACE ELEVATION: --- MSL LI Q U I D LI M I T PL A S T I C LI M I T SA M P L E FIELD RESULTS WATER DEPTH: Dry CAVE DEPTH: 8 feet READING TAKEN: At Completion GR A P H I C L O G BORING NO. B-1 PO C K E T P E N . (T S F ) DRILLING DATE: 11/1/21 DRILLING METHOD: Hollow Stem Auger LOGGED BY: Jamie Hayward OR G A N I C CO N T E N T ( % ) DR Y D E N S I T Y (P C F ) DE P T H ( F E E T ) MO I S T U R E CO N T E N T ( % ) JOB NO.: 21G260-1 PROJECT: Proposed Warehouse LOCATION: Fontana, California PLATE B-1 TB L 2 1 G 2 6 0 - 1 . G P J S O C A L G E O . G D T 1 2 / 8 / 2 1 ALLUVIUM: Gray Brown Silty fine to coarse Sand, trace fine tocoarse Gravel, dense-dry Gray Brown fine to coarse Sand, little fine to coarse Gravel, trace Silt, dense to very dense-damp Boring Terminated at 20' 30 33 47 71 50/5" 50/4" 1 2 2 2 2 2 5 10 15 20 LABORATORY RESULTS CO M M E N T S TEST BORING LOG PA S S I N G #2 0 0 S I E V E ( % ) BL O W C O U N T DESCRIPTION SURFACE ELEVATION: --- MSL LI Q U I D LI M I T PL A S T I C LI M I T SA M P L E FIELD RESULTS WATER DEPTH: Dry CAVE DEPTH: 7 feet READING TAKEN: At Completion GR A P H I C L O G BORING NO. B-2 PO C K E T P E N . (T S F ) DRILLING DATE: 11/1/21 DRILLING METHOD: Hollow Stem Auger LOGGED BY: Jamie Hayward OR G A N I C CO N T E N T ( % ) DR Y D E N S I T Y (P C F ) DE P T H ( F E E T ) MO I S T U R E CO N T E N T ( % ) JOB NO.: 21G260-1 PROJECT: Proposed Warehouse LOCATION: Fontana, California PLATE B-2 TB L 2 1 G 2 6 0 - 1 . G P J S O C A L G E O . G D T 1 2 / 8 / 2 1 ALLUVIUM: Gray Brown Gravelly fine to coarse Sand, occasionalCobbles, very dense-dry to damp @ 13½ feet, dense Boring Terminated at 15' Disturbed Sample 50/5" 87/10" 50/5" 50/2" 76/11" 49 1 1 2 5 10 15 LABORATORY RESULTS CO M M E N T S TEST BORING LOG PA S S I N G #2 0 0 S I E V E ( % ) BL O W C O U N T DESCRIPTION SURFACE ELEVATION: --- MSL LI Q U I D LI M I T PL A S T I C LI M I T SA M P L E FIELD RESULTS WATER DEPTH: Dry CAVE DEPTH: 7 feet READING TAKEN: At Completion GR A P H I C L O G BORING NO. B-3 PO C K E T P E N . (T S F ) DRILLING DATE: 11/1/21 DRILLING METHOD: Hollow Stem Auger LOGGED BY: Jamie Hayward OR G A N I C CO N T E N T ( % ) DR Y D E N S I T Y (P C F ) DE P T H ( F E E T ) MO I S T U R E CO N T E N T ( % ) JOB NO.: 21G260-1 PROJECT: Proposed Warehouse LOCATION: Fontana, California PLATE B-3 TB L 2 1 G 2 6 0 - 1 . G P J S O C A L G E O . G D T 1 2 / 8 / 2 1 ALLUVIUM: Gray Brown Silty fine Sand, little medium to coarseSand, trace fine to coarse Gravel, medium dense-dry Gray Brown fine to coarse Sand, little Silt, little fine to coarse Gravel, occasional to abundant Cobbles, medium dense to verydense-dry to damp Boring Terminated at 20' 34 41 38 75 36 52 71/9" 134 118 121 123 1 1 2 2 2 2 5 10 15 20 LABORATORY RESULTS CO M M E N T S TEST BORING LOG PA S S I N G #2 0 0 S I E V E ( % ) BL O W C O U N T DESCRIPTION SURFACE ELEVATION: --- MSL LI Q U I D LI M I T PL A S T I C LI M I T SA M P L E FIELD RESULTS WATER DEPTH: Dry CAVE DEPTH: 4 feet READING TAKEN: At Completion GR A P H I C L O G BORING NO. B-4 PO C K E T P E N . (T S F ) DRILLING DATE: 11/1/21 DRILLING METHOD: Hollow Stem Auger LOGGED BY: Jamie Hayward OR G A N I C CO N T E N T ( % ) DR Y D E N S I T Y (P C F ) DE P T H ( F E E T ) MO I S T U R E CO N T E N T ( % ) JOB NO.: 21G260-1 PROJECT: Proposed Warehouse LOCATION: Fontana, California PLATE B-4 TB L 2 1 G 2 6 0 - 1 . G P J S O C A L G E O . G D T 1 2 / 8 / 2 1 ALLUVIUM: Gray Brown Silty fine Sand, little medium to coarseSand, medium dense-dry Gray Brown fine to coarse Sand, little fine to coarse Gravel,medium dense to very dense-dry to damp @ 7 feet, occasional to abundant Cobbles Boring Terminated at 25' Disturbed Sample 42 49 41 56 22 68 50/2" 50/5" 110 126 121 121 1 3 2 2 2 3 3 5 10 15 20 25 LABORATORY RESULTS CO M M E N T S TEST BORING LOG PA S S I N G #2 0 0 S I E V E ( % ) BL O W C O U N T DESCRIPTION SURFACE ELEVATION: --- MSL LI Q U I D LI M I T PL A S T I C LI M I T SA M P L E FIELD RESULTS WATER DEPTH: Dry CAVE DEPTH: 6 feet READING TAKEN: At Completion GR A P H I C L O G BORING NO. B-5 PO C K E T P E N . (T S F ) DRILLING DATE: 11/1/21 DRILLING METHOD: Hollow Stem Auger LOGGED BY: Jamie Hayward OR G A N I C CO N T E N T ( % ) DR Y D E N S I T Y (P C F ) DE P T H ( F E E T ) MO I S T U R E CO N T E N T ( % ) JOB NO.: 21G260-1 PROJECT: Proposed Warehouse LOCATION: Fontana, California PLATE B-5 TB L 2 1 G 2 6 0 - 1 . G P J S O C A L G E O . G D T 1 2 / 8 / 2 1 ALLUVIUM: Light Gray Brown Silty fine Sand, little medium tocoarse Sand, trace fine Gravel, medium dense-dry to damp Gray Brown fine to coarse Sand, little fine to coarse Gravel, trace Silt, dense to very dense-dry to damp Boring Terminated at 20' 17 38 57 63 53 47 2 1 1 1 2 3 5 10 15 20 LABORATORY RESULTS CO M M E N T S TEST BORING LOG PA S S I N G #2 0 0 S I E V E ( % ) BL O W C O U N T DESCRIPTION SURFACE ELEVATION: --- MSL LI Q U I D LI M I T PL A S T I C LI M I T SA M P L E FIELD RESULTS WATER DEPTH: Dry CAVE DEPTH: 6 feet READING TAKEN: At Completion GR A P H I C L O G BORING NO. B-6 PO C K E T P E N . (T S F ) DRILLING DATE: 11/1/21 DRILLING METHOD: Hollow Stem Auger LOGGED BY: Jamie Hayward OR G A N I C CO N T E N T ( % ) DR Y D E N S I T Y (P C F ) DE P T H ( F E E T ) MO I S T U R E CO N T E N T ( % ) JOB NO.: 21G260-1 PROJECT: Proposed Warehouse LOCATION: Fontana, California PLATE B-6 TB L 2 1 G 2 6 0 - 1 . G P J S O C A L G E O . G D T 1 2 / 8 / 2 1 ALLUVIUM: Light Brown Silty fine to medium Sand, trace fineGravel, medium dense-dry Brown fine to medium Sand, little Silt, little fine Gravel, traceSand, dense-dry Boring Terminated at 5' 5 LABORATORY RESULTS CO M M E N T S TEST BORING LOG PA S S I N G #2 0 0 S I E V E ( % ) BL O W C O U N T DESCRIPTION SURFACE ELEVATION: --- MSL LI Q U I D LI M I T PL A S T I C LI M I T SA M P L E FIELD RESULTS WATER DEPTH: Dry CAVE DEPTH: 5 feet READING TAKEN: At Completion GR A P H I C L O G BORING NO. B-7 PO C K E T P E N . (T S F ) DRILLING DATE: 11/16/21 DRILLING METHOD: Hand Auger LOGGED BY: Caleb Brackett OR G A N I C CO N T E N T ( % ) DR Y D E N S I T Y (P C F ) DE P T H ( F E E T ) MO I S T U R E CO N T E N T ( % ) JOB NO.: 21G260-1 PROJECT: Proposed Warehouse LOCATION: Fontana, California PLATE B-7 TB L 2 1 G 2 6 0 - 1 . G P J S O C A L G E O . G D T 1 2 / 8 / 2 1 Classification: Gray Brown fine to coarse Sand, lttle fine to coarse Gravel Boring Number:B-1 Initial Moisture Content (%)2 Sample Number:---Final Moisture Content (%)11 Depth (ft)5 to 6 Initial Dry Density (pcf)118.3 Specimen Diameter (in)2.4 Final Dry Density (pcf)125.2 Specimen Thickness (in)1.0 Percent Collapse (%)0.41 Proposed Warehouse Fontana, California Project No. 21G260-1 PLATE C-1 0 2 4 6 8 10 12 14 16 18 20 0.1 1 10 100 Consolidation Strain (%) Load (ksf) Consolidation/Collapse Test Results Water Added at 1600 psf Classification: Gray Brown fine to coarse Sand, lttle fine to coarse Gravel Boring Number:B-5 Initial Moisture Content (%)2 Sample Number:---Final Moisture Content (%)12 Depth (ft)3 to 4 Initial Dry Density (pcf)126.1 Specimen Diameter (in)2.4 Final Dry Density (pcf)138.1 Specimen Thickness (in)1.0 Percent Collapse (%)2.16 Proposed Warehouse Fontana, California Project No. 21G260-1 PLATE C-2 0 2 4 6 8 10 12 14 16 18 20 0.1 1 10 100 Consolidation Strain (%) Load (ksf) Consolidation/Collapse Test Results Water Added at 1600 psf Classification: Gray Brown fine to coarse Sand, lttle fine to coarse Gravel Boring Number:B-5 Initial Moisture Content (%)2 Sample Number:---Final Moisture Content (%)13 Depth (ft)5 to 6 Initial Dry Density (pcf)121.4 Specimen Diameter (in)2.4 Final Dry Density (pcf)129.3 Specimen Thickness (in)1.0 Percent Collapse (%)0.19 Proposed Warehouse Fontana, California Project No. 21G260-1 PLATE C-3 0 2 4 6 8 10 12 14 16 18 20 0.1 1 10 100 Consolidation Strain (%) Load (ksf) Consolidation/Collapse Test Results Water Added at 1600 psf Classification: Gray Brown fine to coarse Sand, lttle fine to coarse Gravel Boring Number:B-5 Initial Moisture Content (%)2 Sample Number:---Final Moisture Content (%)11 Depth (ft)7 to 8 Initial Dry Density (pcf)121.4 Specimen Diameter (in)2.4 Final Dry Density (pcf)128.1 Specimen Thickness (in)1.0 Percent Collapse (%)0.29 Proposed Warehouse Fontana, California Project No. 21G260-1 PLATE C-4 0 2 4 6 8 10 12 14 16 18 20 0.1 1 10 100 Consolidation Strain (%) Load (ksf) Consolidation/Collapse Test Results Water Added at 1600 psf Proposed Warehouse Fontana, California Project No. 21G260-1 PLATE C-5 116 118 120 122 124 126 128 130 132 134 136 138 0 2 4 6 8 10 12 14 Dry Density (lbs/ft3) Moisture Content (%) Moisture/Density Relationship ASTM D-1557 Soil ID Number B-5 @ 0-5' Optimum Moisture (%)8 Maximum Dry Density (pcf)128.5 Soil Classification Gray Brown Silty fine to coarse Sand, trace fine to coarse Gravel Zero Air Voids Curve: Specific Gravity = 2.7 Grading Guide Specifications Page 1 GRADING GUIDE SPECIFICATIONS These grading guide specifications are intended to provide typical procedures for grading operations. They are intended to supplement the recommendations contained in the geotechnical investigation report for this project. Should the recommendations in the geotechnical investigation report conflict with the grading guide specifications, the more site specific recommendations in the geotechnical investigation report will govern. General • The Earthwork Contractor is responsible for the satisfactory completion of all earthwork in accordance with the plans and geotechnical reports, and in accordance with city, county, and applicable building codes. • The Geotechnical Engineer is the representative of the Owner/Builder for the purpose of implementing the report recommendations and guidelines. These duties are not intended to relieve the Earthwork Contractor of any responsibility to perform in a workman-like manner, nor is the Geotechnical Engineer to direct the grading equipment or personnel employed by the Contractor. • The Earthwork Contractor is required to notify the Geotechnical Engineer of the anticipated work and schedule so that testing and inspections can be provided. If necessary, work may be stopped and redone if personnel have not been scheduled in advance. • The Earthwork Contractor is required to have suitable and sufficient equipment on the job- site to process, moisture condition, mix and compact the amount of fill being placed to the approved compaction. In addition, suitable support equipment should be available to conform with recommendations and guidelines in this report. • Canyon cleanouts, overexcavation areas, processed ground to receive fill, key excavations, subdrains and benches should be observed by the Geotechnical Engineer prior to placement of any fill. It is the Earthwork Contractor's responsibility to notify the Geotechnical Engineer of areas that are ready for inspection. • Excavation, filling, and subgrade preparation should be performed in a manner and sequence that will provide drainage at all times and proper control of erosion. Precipitation, springs, and seepage water encountered shall be pumped or drained to provide a suitable working surface. The Geotechnical Engineer must be informed of springs or water seepage encountered during grading or foundation construction for possible revision to the recommended construction procedures and/or installation of subdrains. Site Preparation • The Earthwork Contractor is responsible for all clearing, grubbing, stripping and site preparation for the project in accordance with the recommendations of the Geotechnical Engineer. • If any materials or areas are encountered by the Earthwork Contractor which are suspected of having toxic or environmentally sensitive contamination, the Geotechnical Engineer and Owner/Builder should be notified immediately. Grading Guide Specifications Page 2 • Major vegetation should be stripped and disposed of off-site. This includes trees, brush, heavy grasses and any materials considered unsuitable by the Geotechnical Engineer. • Underground structures such as basements, cesspools or septic disposal systems, mining shafts, tunnels, wells and pipelines should be removed under the inspection of the Geotechnical Engineer and recommendations provided by the Geotechnical Engineer and/or city, county or state agencies. If such structures are known or found, the Geotechnical Engineer should be notified as soon as possible so that recommendations can be formulated. • Any topsoil, slopewash, colluvium, alluvium and rock materials which are considered unsuitable by the Geotechnical Engineer should be removed prior to fill placement. • Remaining voids created during site clearing caused by removal of trees, foundations basements, irrigation facilities, etc., should be excavated and filled with compacted fill. • Subsequent to clearing and removals, areas to receive fill should be scarified to a depth of 10 to 12 inches, moisture conditioned and compacted • The moisture condition of the processed ground should be at or slightly above the optimum moisture content as determined by the Geotechnical Engineer. Depending upon field conditions, this may require air drying or watering together with mixing and/or discing. Compacted Fills • Soil materials imported to or excavated on the property may be utilized in the fill, provided each material has been determined to be suitable in the opinion of the Geotechnical Engineer. Unless otherwise approved by the Geotechnical Engineer, all fill materials shall be free of deleterious, organic, or frozen matter, shall contain no chemicals that may result in the material being classified as “contaminated,” and shall be very low to non-expansive with a maximum expansion index (EI) of 50. The top 12 inches of the compacted fill should have a maximum particle size of 3 inches, and all underlying compacted fill material a maximum 6-inch particle size, except as noted below. • All soils should be evaluated and tested by the Geotechnical Engineer. Materials with high expansion potential, low strength, poor gradation or containing organic materials may require removal from the site or selective placement and/or mixing to the satisfaction of the Geotechnical Engineer. • Rock fragments or rocks less than 6 inches in their largest dimensions, or as otherwise determined by the Geotechnical Engineer, may be used in compacted fill, provided the distribution and placement is satisfactory in the opinion of the Geotechnical Engineer. • Rock fragments or rocks greater than 12 inches should be taken off-site or placed in accordance with recommendations and in areas designated as suitable by the Geotechnical Engineer. These materials should be placed in accordance with Plate D-8 of these Grading Guide Specifications and in accordance with the following recommendations: • Rocks 12 inches or more in diameter should be placed in rows at least 15 feet apart, 15 feet from the edge of the fill, and 10 feet or more below subgrade. Spaces should be left between each rock fragment to provide for placement and compaction of soil around the fragments. • Fill materials consisting of soil meeting the minimum moisture content requirements and free of oversize material should be placed between and over the rows of rock or Grading Guide Specifications Page 3 concrete. Ample water and compactive effort should be applied to the fill materials as they are placed in order that all of the voids between each of the fragments are filled and compacted to the specified density. • Subsequent rows of rocks should be placed such that they are not directly above a row placed in the previous lift of fill. A minimum 5-foot offset between rows is recommended. • To facilitate future trenching, oversized material should not be placed within the range of foundation excavations, future utilities or other underground construction unless specifically approved by the soil engineer and the developer/owner representative. • Fill materials approved by the Geotechnical Engineer should be placed in areas previously prepared to receive fill and in evenly placed, near horizontal layers at about 6 to 8 inches in loose thickness, or as otherwise determined by the Geotechnical Engineer for the project. • Each layer should be moisture conditioned to optimum moisture content, or slightly above, as directed by the Geotechnical Engineer. After proper mixing and/or drying, to evenly distribute the moisture, the layers should be compacted to at least 90 percent of the maximum dry density in compliance with ASTM D-1557-78 unless otherwise indicated. • Density and moisture content testing should be performed by the Geotechnical Engineer at random intervals and locations as determined by the Geotechnical Engineer. These tests are intended as an aid to the Earthwork Contractor, so he can evaluate his workmanship, equipment effectiveness and site conditions. The Earthwork Contractor is responsible for compaction as required by the Geotechnical Report(s) and governmental agencies. • Fill areas unused for a period of time may require moisture conditioning, processing and recompaction prior to the start of additional filling. The Earthwork Contractor should notify the Geotechnical Engineer of his intent so that an evaluation can be made. • Fill placed on ground sloping at a 5-to-1 inclination (horizontal-to-vertical) or steeper should be benched into bedrock or other suitable materials, as directed by the Geotechnical Engineer. Typical details of benching are illustrated on Plates D-2, D-4, and D-5. • Cut/fill transition lots should have the cut portion overexcavated to a depth of at least 3 feet and rebuilt with fill (see Plate D-1), as determined by the Geotechnical Engineer. • All cut lots should be inspected by the Geotechnical Engineer for fracturing and other bedrock conditions. If necessary, the pads should be overexcavated to a depth of 3 feet and rebuilt with a uniform, more cohesive soil type to impede moisture penetration. • Cut portions of pad areas above buttresses or stabilizations should be overexcavated to a depth of 3 feet and rebuilt with uniform, more cohesive compacted fill to impede moisture penetration. • Non-structural fill adjacent to structural fill should typically be placed in unison to provide lateral support. Backfill along walls must be placed and compacted with care to ensure that excessive unbalanced lateral pressures do not develop. The type of fill material placed adjacent to below grade walls must be properly tested and approved by the Geotechnical Engineer with consideration of the lateral earth pressure used in the design. Grading Guide Specifications Page 4 Foundations • The foundation influence zone is defined as extending one foot horizontally from the outside edge of a footing, and proceeding downward at a ½ horizontal to 1 vertical (0.5:1) inclination. • Where overexcavation beneath a footing subgrade is necessary, it should be conducted so as to encompass the entire foundation influence zone, as described above. • Compacted fill adjacent to exterior footings should extend at least 12 inches above foundation bearing grade. Compacted fill within the interior of structures should extend to the floor subgrade elevation. Fill Slopes • The placement and compaction of fill described above applies to all fill slopes. Slope compaction should be accomplished by overfilling the slope, adequately compacting the fill in even layers, including the overfilled zone and cutting the slope back to expose the compacted core • Slope compaction may also be achieved by backrolling the slope adequately every 2 to 4 vertical feet during the filling process as well as requiring the earth moving and compaction equipment to work close to the top of the slope. Upon completion of slope construction, the slope face should be compacted with a sheepsfoot connected to a sideboom and then grid rolled. This method of slope compaction should only be used if approved by the Geotechnical Engineer. • Sandy soils lacking in adequate cohesion may be unstable for a finished slope condition and therefore should not be placed within 15 horizontal feet of the slope face. • All fill slopes should be keyed into bedrock or other suitable material. Fill keys should be at least 15 feet wide and inclined at 2 percent into the slope. For slopes higher than 30 feet, the fill key width should be equal to one-half the height of the slope (see Plate D-5). • All fill keys should be cleared of loose slough material prior to geotechnical inspection and should be approved by the Geotechnical Engineer and governmental agencies prior to filling. • The cut portion of fill over cut slopes should be made first and inspected by the Geotechnical Engineer for possible stabilization requirements. The fill portion should be adequately keyed through all surficial soils and into bedrock or suitable material. Soils should be removed from the transition zone between the cut and fill portions (see Plate D- 2). Cut Slopes • All cut slopes should be inspected by the Geotechnical Engineer to determine the need for stabilization. The Earthwork Contractor should notify the Geotechnical Engineer when slope cutting is in progress at intervals of 10 vertical feet. Failure to notify may result in a delay in recommendations. • Cut slopes exposing loose, cohesionless sands should be reported to the Geotechnical Engineer for possible stabilization recommendations. • All stabilization excavations should be cleared of loose slough material prior to geotechnical inspection. Stakes should be provided by the Civil Engineer to verify the location and dimensions of the key. A typical stabilization fill detail is shown on Plate D-5. Grading Guide Specifications Page 5 • Stabilization key excavations should be provided with subdrains. Typical subdrain details are shown on Plates D-6. Subdrains • Subdrains may be required in canyons and swales where fill placement is proposed. Typical subdrain details for canyons are shown on Plate D-3. Subdrains should be installed after approval of removals and before filling, as determined by the Soils Engineer. • Plastic pipe may be used for subdrains provided it is Schedule 40 or SDR 35 or equivalent. Pipe should be protected against breakage, typically by placement in a square-cut (backhoe) trench or as recommended by the manufacturer. • Filter material for subdrains should conform to CALTRANS Specification 68-1.025 or as approved by the Geotechnical Engineer for the specific site conditions. Clean ¾-inch crushed rock may be used provided it is wrapped in an acceptable filter cloth and approved by the Geotechnical Engineer. Pipe diameters should be 6 inches for runs up to 500 feet and 8 inches for the downstream continuations of longer runs. Four-inch diameter pipe may be used in buttress and stabilization fills. GRADING GUIDE SPECIFICATIONS NOT TO SCALE DRAWN: JAS CHKD: GKM PLATE D-2 FILL ABOVE CUT SLOPE DETAIL 9' MIN. 4' TYP. MINIMUM 1' TILT BACK OR 2% SLOPE (WHICHEVER IS GREATER) REMOVE U N S U I T A B L E M A T E R I A L BENCHING DIMENSIONS IN ACCORDANCE WITH PLAN OR AS RECOMMENDED BY THE GEOTECHNICAL ENGINEER CUT SLOPE TO BE CONSTRUCTED PRIOR TO PLACEMENT OF FILL BEDROCK OR APPROVED COMPETENT MATERIAL CUT SLOPE NATURAL GRADE CUT/FILL CONTACT TO BE SHOWN ON "AS-BUILT" COMPETENT MATERIAL CUT/FILL CONTACT SHOWN ON GRADING PLAN NEW COMPACTED FILL 10' TYP. KEYWAY IN COMPETENT MATERIAL MINIMUM WIDTH OF 15 FEET OR AS RECOMMENDED BY THE GEOTECHNICAL ENGINEER. KEYWAY MAY NOT BE REQUIRED IF FILL SLOPE IS LESS THAN 5 FEET IN HEIGHT AS RECOMMENDED BY THE GEOTECHNICAL ENGINEER. GRADING GUIDE SPECIFICATIONS NOT TO SCALE DRAWN: JAS CHKD: GKM PLATE D-4 FILL ABOVE NATURAL SLOPE DETAIL 10' TYP.4' TYP. (WHICHEVER IS GREATER) OR 2% SLOPE MINIMUM 1' TILT BACK REMOVE UN S U I T A B L E M A T E R I A L NEW COMPACTED FILL COMPETENT MATERIAL KEYWAY IN COMPETENT MATERIAL. RECOMMENDED BY THE GEOTECHNIAL ENGINEER. KEYWAY MAY NOT BE REQUIRED IF FILL SLOPE IS LESS THAN 5' IN HEIGHT AS RECOMMENDED BY THE GEOTECHNICAL ENGINEER. 2' MINIMUM KEY DEPTH OVERFILL REQUIREMENTS PER GRADING GUIDE SPECIFICATIONS TOE OF SLOPE SHOWN ON GRADING PLAN BACKCUT - VARIES PLACE COMPACTED BACKFILL TO ORIGINAL GRADE PROJECT SLOPE GRADIENT (1:1 MAX.) NOTE: BENCHING SHALL BE REQUIRED WHEN NATURAL SLOPES ARE EQUAL TO OR STEEPER THAN 5:1 OR WHEN RECOMMENDED BY THE GEOTECHNICAL ENGINEER. FINISHED SLOPE FACE MINIMUM WIDTH OF 15 FEET OR AS BENCHING DIMENSIONS IN ACCORDANCE WITH PLAN OR AS RECOMMENDED BY THE GEOTECHNICAL ENGINEER GRADING GUIDE SPECIFICATIONS NOT TO SCALE DRAWN: JAS CHKD: GKM PLATE D-5 STABILIZATION FILL DETAIL FACE OF FINISHED SLOPE COMPACTED FILL MINIMUM 1' TILT BACK OR 2% SLOPE (WHICHEVER IS GREATER) 10' TYP. 2' MINIMUM KEY DEPTH 3' TYPICAL BLANKET FILL IF RECOMMENDED BY THE GEOTECHNICAL ENGINEER COMPETENT MATERIAL ACCEPTABLE TO THE SOIL ENGINEER KEYWAY WIDTH, AS SPECIFIED BY THE GEOTECHNICAL ENGINEER TOP WIDTH OF FILL AS SPECIFIED BY THE GEOTECHNICAL ENGINEER BENCHING DIMENSIONS IN ACCORDANCE WITH PLAN OR AS RECOMMENDED BY THE GEOTECHNICAL ENGINEER 4' TYP. PROPOSED WAREHOUSE DRAWN: MD CHKD: RGT SCG PROJECT 21G260-1 PLATE E-1 SEISMIC DESIGN PARAMETERS - 2019 CBC FONTANA, CALIFORNIA SOURCE: SEAOC/OSHPD Seismic Design Maps Tool <https://seismicmaps.org/>