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HomeMy WebLinkAboutTract 7352 Sump Soils ReportGeotechnical Investigation Vesting Tentative Tract 7352 APN's: 538-010-07 & 538-010-35, Bakersfield, CA SOILS ENGINEERING, INC. SE/ File 19-17319 November 27, 2019 Page 5 E. SUMP INVESTIGATION Boring 5 & 6 were drilled to a maximum depth of forty-one and a half (41.5) feet below existing ground surface in the proposed sump area. Cohesionless sandy material were encountered at the invert level (see Table 1) consisting of silty sand and Poorly-Graded Sand, classified as SM and SP, respectively, in the Unified Soils Classification System (USCS). Based on our field investigation and our laboratory testing program, it is our engineering opinion that the majority of the sump areas can be expected to have highly permeable subsurface soils (See permeability test rates, shown on the Laboratory Summary Table 1, attached) as shown on the boring logs, attached. Accordingly, the proposed sump shall drain in seven days or less. During the construction process, our field representative will review the construction process of the proposed sump. A letter will be issued stating compliance with these requirements when the construction of the sump is complete. G. SEISMIC DESIGN VALUES The seismic design values presented in the table below are based on the 2019 California Building Code (CBC). The Site Class for the proposed project was determined using standard penetration test data obtained at the site and are provided in the attached Boring Logs. The site is not located within an Alquist-Priolo (earthquake fault) Special Study Zone. The table on the following page 6 details the Seismic Design Criteria. ©2019 SOILS ENGINEERING, INC. Geotechnical Investigation Vesting Tentative Tract 7352 APN's: 538-010-07 & 538-010-35, Bakersfield, CA SOILS ENGINEERING, INC. SE/ File 19-17319 November 27, 2019 Page9 above requirements shall be segregated and not used for this project or the various layers shall be thoroughly mixed prior to acceptance testing by the Geotechnical Engineer. The contractor shall provide sufficient advance notice, prior to import operations, to allow testing and evaluation of the proposed import materials. Because of the time needed to perform the above tests, the contractor shall provide a means by which the Geotechnical Engineer or others can verify that the soil(s) which was sampled and tested is the same soil(s) which 1s being imported to the project. F.DRAINAGE Finished ground grades adjacent to the proposed buildings should be sloped to provide positive free drainage away from the foundations. No areas should be constructed that would allow drainage generated on the site, or water impinging upon the site from outside sources, to pond near footings and slabs or behind curbs. Where ground surfaces adjacent to subsurface walls are to be landscaped, walls should be waterproofed. Installation of gravel-filled drains to route subsurface drainage away from walls will reduce the thickness of damp-proofing resulting in a considerable savings. G.SLOPES Both fill and cut slopes should be constructed at 2: 1 (horizontal to vertical) in accordance with the 2016 Uniform Building Code. Finished slopes nearer than five feet from building foundations should be graded no steeper than five horizontal to one vertical (5: 1 ). A slope ratio of two horizontal to one vertical (2: 1) should provide adequate stability for slopes farther than five feet from footing lines. The fill slopes shall be compacted to a minimum of 90% of ASTM D- 1557 and in accordance with the Guide specifications for Earthwork, Appendix A. This may be achieved by overfilling the constructed slope and trimming to a compacted finished surface, rolling the slope face with a sheepsfoot as the level of the fill is raised, or any method that achieves the desired product. The cut portion of the slope should be constructed first. Prior to construction of the fill slope, incompetent surface soils should be removed from the top of the cut. Areas to receive fill or to support structures, slabs or pavements should be removed of all vegetation, debris and disturbed soils. All existing uncertified fill soils should be excavated to expose competent native soils. Existing underground pipelines, private sewage disposal systems and any water or oil wells, if encountered during grading, should be removed or capped in accordance with procedures considered acceptable by the appropriate governing agency. Tree roots to 2 inches in diameter should be removed. Both fill and cut slopes will be subject to erosion immediately after grading and should be designed to reduce surficial sloughing by implementing a permanent slope maintenance program as soon as practical after completion of slope construction. Slope maintenance should include proper care of erosion and drainage control devices, rodent control, and immediate planting with deep-rooting, lightweight, drought-resistant vegetation. An erosion control geotextile may also be used in combination with vegetation to control erosion. Experience has shown that slope performance is largely dependent upon proper slope maintenance (i.e., planting, proper watering, clearing of drainage devices, etc.). Slopes properly placed and conscientiously maintained are not expected to display excessive raveling or sloughing. ©2019 SOILS ENGINEERING, INC. Geotechnical Investigation Vesting Tentative Tract 7352 APN’s: 538-010-07 & 538-010-35, Bakersfield, CA SEI File 19-17319 November 27, 2019 Page 21 ©2019 SOILS ENGINEERING, INC. APPENDIX C SOIL TEST DATA SIEVE ANALYSES (ASTM D1140) Grain size distributions for samples selected as most representative of sub-soils encountered in our test borings were determined by sieve analysis (ASTM Test Method D422). Test results are shown in Figures A-1 through A-10. IN-SITU DENSITY & MOISTURE RELATIONSHIPS (ASTM D2216 & D2937) Moisture & density data for undisturbed native soils was obtained by use of a 2-3/8-inch (inside diameter) split-barrel sampler. Test results are given on the Test Boring Logs. CONSOLIDATION TESTS (ASTM D2435) Compressibility of soils was determined on saturated, undisturbed samples of native materials. Consolidation Test Diagrams, Figures B-1 through B-4, graphically express the relationship of vertical strain vs. applied vertical (normal) load for earth materials selected as most representative of the soil strata within the anticipated zone of influence of foundation loads. DIRECT SHEAR TESTS (ASTM D3080) Four (4) quick-consolidated direct shear tests were performed on an undisturbed, saturated sample of native earth materials. This test provides information on soil shear strength vs. normal load and is used to determine the angle of internal friction and cohesion of earth materials under essentially drained conditions. Test results are presented in Figure C-1 through C-4. R-VALUE TESTS (CTM-301) Three (3) R-Value tests were performed in accordance with Test Method No. California 301-F to obtain flexible pavement design data. Test results are given in Figures D-1 through D-3. PERMEABILITY TESTS (ASTM D2434) Permeability of in-situ soil specimens were determined by the Constant Head Method. Test results are shown on the Laboratory Testing Recap Table 1. SOIL CORROSIVITY (SO4 / pH / Chlorides) Tests for Soluble Sulfates (SO4), Soluble Chlorides (Cl), and pH values were performed on two (2) composite samples taken from the upper 3 feet to determine the corrosion potential of the soils. Corrosion prevention measures and the extent to which measures should be taken (if any) should be addressed with the corrosion engineer. Soluble Sulfates and Soluble Chlorides values were determined according to EPA 300.0M. The pH values were determined according to EPA 9045C. Result of the constituent is discussed in the report, under the Soil Corrosivity section.