COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

i i= Geomatrix i The Facilities are located within the San Joaquin Hydrologic Basin (DWR, 1975). The hydrogeologic units consist of consolidated rocks of the Victor Formation, the Laguna Formation, and the Mehrten Formation, and unconsolidated deposits composed of fluvial, lacustrine, and marsh deposits. The unconsolidated deposits are the main water-bearing formations in the basin. Regional groundwater flow in this area is reportedly to the north, northwest, and northeast (San Joaquin County Flood Control and Water Conservation District, 1999). 3.2 SITE-SPECIFIC Site-specific lithologic and hydrogeologic information for the Facilities are presented in the following subsections. 3.2.1 Lathrop Facility At the Lathrop Facility, soil was reported to be composed of interbedded silty sand, sandy silt, and clayey silt from ground surface to a depth of approximately 20 feet. During the installation of groundwater monitoring wells LPW-1, LPW-2, and LPW-3 groundwater was reportedly encountered in the well borings at depths between 19 and 21 feet in sand (borings LPW-1 and LPW-3) and clayey sand (boring LPW-2). Below the sandy soils, a clayey silt and silty clay was reported at depth of approximately 22.5 feet (boring LPW-3) and 26 feet(boring LPW-2). At the Lathrop Facility, groundwater monitoring data indicated a groundwater flow direction to the northeast at a gradient between 0.003 feet/foot (ft/ft) and 0.005 ft/ft (URS,May 2004). Although the measured groundwater elevations in June 2005 were approximately 4 feet higher than the elevations reported for the November 2004 event, the groundwater flow direction was similar to the historical monitoring results. In June 2005, the groundwater gradient was reported 0.004 ft/ft with a flow direction to the north-northeast (Geomatrix 2005). 3.2.2 French Camp Facility At the French Camp Facility, soil was reported to be composed of interbedded silty sands, clayey silts, and silty clays to a depth of approximately 28 feet. During the installation of groundwater monitoring wells FCW-1, FCW-2, and FCW-3 groundwater was reportedly encountered in the well borings below depths of approximately 26 and 28 feet in sand(boring FCW-1), silty sand to sand(boring FCW-2), and silty sand(boring FCW-3). In boring FCW-3, sandyclay and clayey silt was encountered at a depth of approximately 28.5 feet. PAI 0626.000.0\Docs\MLT Soil Work Plan.doc 5