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• • Kennedy/Jenks Consultants movement(SJRGA 1999). The most extensive is the Corcoran Clay of the Tulare Formation, encountered between approximately 100 and 400 feet bgs mainly west of the San Joaquin River (DWR 1967). Where present, the Corcoran Clay serves as a confining layer dividing upper unconfined aquifers from lower, confined aquifers (SJRGA 1999). The Facility and LAA are located in the San Joaquin River Hydrologic Region, Eastern San Joaquin Subbasin (Subbasin 5-22.01) (DWR 1967). The Subbasin contains three important hydrogeologic formations: the Victor, the Laguna, and the Mehrten. The Laguna Formation (occurring mainly east of the San Joaquin River) is generally coeval to the Tulare Formation (occurring mainly west of the San Joaquin River) (DWR 1967). The generally coarser-grained Victor Formation extends from the ground surface to about 150 feet bgs and is underlain by the Laguna Formation. The Laguna Formation is 600 to 1,000 feet thick and is composed of discontinuous lenses of unconsolidated to semi-consolidated sands and silts with lesser amounts of gravel and silt(SJRGA 1999). DWR (1967) records for wells in the vicinity of the Site indicated that the average completion depth is 200 feet bgs, which means that the wells are likely intercepting the Victor and Laguna Formations. Wells installed in the Victor Formation could produce 650 gallons per minute (gpm); the formation has a specific capacity of 60 gpm per foot (gpm/ft)and a transmissivity of 87,600 gallons per day per foot(gpd/ft). Recharge to the aquifer is by rainfall, return irrigation, and from waters of traversing streams (DWR 1967). Wells installed in the underlying Laguna Formation offer somewhat greater production, estimated at 900 gpm, with specific capacity of 35 gpm/ft and transmissivity of 59,500 gpd/ft. 1.6.2 Soil Soils have been characterized using three different sources of information: 1) a general description of the physical and chemical properties for the different soil types underlying the Site obtained from the Soil Survey of San Joaquin County, California (Soil Survey), published by the United States Department of Agriculture, Soil Conservation Service (USDA 1992); 2) in-situ soil boring log data collected and reported to the CRWQCB by Twining (Twining 2000); and 3) soil boring data collected as part of the Groundwater Monitoring Well and Lysimeter Installation Report (Kennedy/Jenks 2003d). According to the Soil Survey, soil parent materials in the area are reported as wind-modified alluvium derived from granitic rock sources and alluvium derived from mixed rock sources, respectively. In addition, there are two soil types described at the Site: Delhi loamy sand, and Veritas fine sandy loam. Both soils are described as having moderately rapid drainage, low available water capacity (due to sandy textures), slopes of 0 to 2%, and effective rooting depths of approximately 60 inches. The rate of water intake where the soils are irrigated has been reported at approximately 1.5 inches per hour. Available water holding capacity for both soil types has been estimated between 0.08 and 0.17 (in/in), which is considered moderate to low, and is based on the high percentage of sand. Flooding on these soils is reported as rare but possible during years of abnormally high precipitation. The following are general descriptions of the upper 5 feet of these soil types, as described by the Soil Survey (USDA 1992): Groundwater Investigation Work Plan Page 8 Barrel Ten Quarter Circle Winery, Escalon, California g:\is-group\adminfob1031030118.08—barrelten\09-reports\gw invest wrk pinVeztdoc