SU0006921 - Laserfiche WebLink

Home Browse Search

i Project Description- Report of Composting Site Information Tracy Material Recovery Facility and Transfer Station 30703 5. Macffiur Drive, Tracy, Califomia 95377 Site Geofogy The project site lies within a reclaimed gravel quarry in alluvial fan deposits of Corral Hollow Creek. Sediments of the Corral Hollow Creek alluvial fan consist of continental, unconsolidated material derived from the Diablo Range. The lithology is a heterogeneous mix of discontinuous layers of argillaceous sand, gravel, silt, and clay, with lenses of poorly sorted coarse sand and gravel, and locally, thin beds of argillaceous limestone, marl, and marly silt. The fine grained deposits are cemented loose to semi-consolidated, the gravel is locally cemented by either by calcium carbonate or gypsum so as to form resistant strata of conglomerate (Sowers, et al., 1993). Discontinuous layers of poorly sorted sandy silts and clays, clayey sand and silty gravels are exposed in the quarry walls (RGH, 1993). Borings drilled at and in the vicinity of the site indicate that the thickness of alluvial deposits is approximately 100 feet. Below these deposits, borings and wells encounter semi-consolidated, poorly sorted, discontinuous deposits of clay, silt, and gravel of the Tulare Formation. . Eight exploratory borings were drilled at the site in July of 1993 by RGH (1993). These borings, located along the edge and in the bottom of the quarry, penetrated to depths of from 9 to 25 feet. The exploratory borings encountered interbedded sand, silt, and gravel, with discontinuous silt and clay layers.to a depth of 25 feet. Groundwater was not encountered during drilling. Local water wells indicate that groundwater is present at a depth of approximately 90 feet below the ground surface. The rim of the quarry, to the south of the excavation, is blanketed by up to 2 feet of sandy clay soil with a low expansion potential. The upper 1 foot of this soil is weak, porous, and compressible, and the lower portions are stiff and stronger. Within the quarry, surface materials consist of approximately 1 foot of loose silty sands and soft sandy silts. Surface soils are underlain by discontinuous layers of dense to very dense silty sands and gravels i to the maximum depth explored by the eight test borings (RGH, 1993). RMC Lonestar Industries leased the project site in 9947 with the intent to mine the site for sand and gravel. Mining activities started at the site in 1971, and continued through 1975. a The mining operation consisted of excavation and hauling only. By 1975, the excavation reached the present depth of 30 to 40 feet below the surface when mining activities ceased because the mineral resources remaining in the quarry had a clay and silt content of over 50 percent, making them uneconomic for mining. In 1986, RMC Lonestar Industries reclaimed the project site to grassland, and was released from further requirement by San Joaquin County;. There is no natural top soil remaining in the abandoned quarry pit. Soil types in the site vicinity include the Capay-Stomar-Zacharias Group (San Joaquin County, 1993). This soil group, when developed on the gentle topography of alluvial fans, is typically characterized by clayey to silty clayey texture, slow permeability, high shrink-swell potential, low erosion potential, and is moderately well drained. 8 Edgar&Associates,Inc. Tracy Compost Fac Proj Desc04231 0 i