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3-8 ♦ A 5- to 10 -foot layer of very stiff yellowish -brown lean clay. This material is moist, with moisture contents between the liquid and plastic limits. A consolidation test indicates that this material is consolidated to approximately three times the effective overburden stress resulting in an overconsolidation ratio (OCR) of 3. The OCR is the ratio of the maximum effective stress the soil has been subjected to in the past (preconsolidation pressure) to the existing effective stress in the soil. A UU triaxial compression test at an approximate depth of 34 feet in CH2M HILL Boring BH -1 indicated a shear strength of 2,286 psf. ♦ A 30 -foot layer of material consisting of very stiff to hard silt and lean clay. This material is moist to wet, with moisture contents between the liquid and plastic limit. The material has an approximate OCR of 1.7 (CH2M HILL Boring BH -1, approximate depth of 78 feet). ♦ Very dense poorly grade sand was observed near the bottom of CH2M HILL Boring BH -1, starting at an approximate depth of 100 feet. Sand was also observed in EMCON's Boring No. 17 to 178 feet. Based on the above subsurface profile, the subsurface soils at the site can be characterized as strong and dense and therefore not subject to significant stability or settlement issues. Moreover, since groundwater occurs below a depth of approximately 60 feet, the potential for liquefaction of site soils appears remote. Two soil borrow studies (Twining, 1991 and Lewis Engineering, 2000) were conducted in the borrow pit area south of the Austin Unit. The results of these studies indicate that soils at elevations of approximately 15 to 25 feet amsl are classified as low plasticity clays (CL) based on the Unified Soil Classification System (USCS) and have laboratory permeabilities ranging from 1 x 10-7 to 1 x 10-8 cm/sec when compacted to above 90 percent relative compaction based on American Society for Testing Materials Method D1557 (ASTM D1557). The other soil borrow study (Twining 1996) was conducted in the borrow area north of the Austin Road Unit. The results of this study indicate that the soils encountered at a depth of approximately 4 to 11 feet below ground surface are classified as a sandy clay and have a laboratory permeability of approximately 3 x 10-8 cm/sec when compacted to above 90 percent relative compaction based on ASTM D1557. 3.6 Floodplain Forward Landfill is located between the North Fork and the South Fork of the South Littlejohn's Creek. Based on the FEMA FIRMs for the San Joaquin Valley, Forward Landfill is located within four FIRM Panels: 049017; 049517; O63OF; and, O635F. From the FIRM Legend, the majority of the landfill is located within "Zone X", which are areas determined to be outside the 0.2 ipercent annual chance being in a floodplain. The area east of Austin Road at the North Fork of Forward Landfill SWT Engineering Joint Technical Document - April 2014 z:\projects\allied waste\forward\five year permit rvw 2013\itd-5 yr pr 2013\text\sec 3_final.doc