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Kennedy/Jenks Consultants ' 3.1.2 Musco Site A Background Groundwater Quality Report (30 July 2004)was submitted by Kennedy/Jenks. ' That report presents data and an analysis of the hydrogeology of the Musco site,which is to the west and southwest of Jepsen Webb Ranch and Valley View Thoroughbred Farm. The Musco facility is located on a Holocene-age alluvial fan. The southwestern portion of Musco's site is located on a mid-fan position, which is composed of coalescing braided streams consisting of sands and gravels. The northwestern portion of the site is located on the distal position of the fan and is composed of interbedded sandy clay, silty clay, and clay. ' Most of the water-bearing zones beneath Musco's site exist as permeable sand/gravel fluvial deposits within the alluvial fan, and they cover the bulk of the near-surface geology. These deposits are spatially variable, such that they are discontinuous laterally and with depth. Three underlying water-bearing zones were identified at the site including: shallow and perched; intermediate; and deep. Each zone has distinct characteristics when plotted on a Stiff Diagram, ' as discussed in the Background Groundwater Quality Report. Groundwater in the shallow and intermediate water-bearing zones flow generally towards the northeast, and are controlled by gravity flow and flow downhill with the surface topography of the alluvial fan. In the deep water- bearing zone, groundwater flows towards the northwest, and is controlled by the regional groundwater gradient of the San Joaquin Valley Basin. ' Groundwater in the shallow water-bearing units each flow from the upper portion of the alluvial fan in primarily the northeast direction. At the fringe of the alluvial fan, these flows merge together within predominantly fine-grained cross-strata. Next, the shallow groundwater leaves the alluvial fan environment and merges into the groundwater of the deep water-bearing zone ' that flows northeast along with the regional groundwater gradient. 3.1.3 San Joaquin Valley Basin The Jepsen Webb Ranch and Valley View Thoroughbred Farm areas are located on the southwest edge of the San Joaquin Valley Basin. Groundwater in the San Joaquin Valley Basin ' occurs under confined and unconfined conditions. Three distinct groundwater bodies exist in much of the valley. In downward succession, these include (1) a body of unconfined and semi- confined fresh water in alluvial deposits overlying a widespread lacustrine confining bed (the ' Corcoran Clay) (2) an extensive reservoir of fresh water confined beneath the Corcoran Clay in alluvial and lacustrine deposits, and (3) a body of saline water contained in marine sediments that underlies the fresh water body throughout the area. (Lofgren, 1976). ' The reclamation areas are specifically located in the Tracy Subbasin of the San Joaquin Valley Basin, which is defined by the areal extent of unconsolidated to semi-consolidated sedimentary ' deposits bounded by the Diablo Range on the west; the Mokelumne and San Joaquin Rivers on the north; the San Joaquin River to the east; and the San Joaquin-Stanislaus County line on the south (DWR, 2003). The Subbasin is drained by the San Joaquin River and one of its major westside tributaries, Corral Hollow Creek. The San Joaquin River flows northward into the Sacramento and San Joaquin Delta and discharges into the San Francisco Bay. Annual precipitation within the subbasin ranges from about 11 inches in the south to about 16 inches in the north (DWR, 2003). Reclamation Report, Page 6 Musco Family Olive Company 9!is I repotten?.1204,dm