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Kennedy/Jenks Consultants ( 100-year return annual total precipitation, as calculated from the probability distribution of the annual precipitation from the 1893 to 2007 precipitation data, is estimated at approximately 32.7 inches per year. Approximately the western third of the facility is located within the 100-year floodplain. ET data range from an average of 0.76 inches/month in December to 7.87 inches/month in July, with an average annual total ET of 50.30 inches per year. 2.2.2 Regional Geology The Central Valley regional aquifer system of California is a 400-mile long, northwest-trending asymmetric trough, averaging 50 miles in width. The significant water-producing geologic units in the Central Valley are the unconsolidated to semi-consolidated non-marine sediments ranging in age from approximately 25 million years to the present. The west side of the trough is bounded by pre-Tertiary and Tertiary marine sedimentary rocks of the Coast Ranges. The east side of the Valley is underlain by pre-Tertiary igneous and metamorphic rocks of the Sierra Nevada foothills (San Joaquin River Group Authority 1999 [SJRGA 1999]). The southern two-thirds of the Central Valley is referred to as the San Joaquin Valley. l The San Joaquin Valley basin contains up to six vertical miles of unconsolidated sediment, of which the top 2,000 feet contain freshwater. As lakes filled and drained over the last 24 million C years, laterally extensive clay units were deposited, forming barriers to vertical groundwater movement (SJRGA 1999). The most extensive is the Corcoran Clay of the Tulare Formation, r encountered at depths between approximately 100 and 400 feet below ground surface (bgs) L mainly west of the San Joaquin River (California Department of Water Resources [DWR] 1967). Where present, the Corcoran Clay serves as a confining layer dividing upper unconfined aquifers from lower confined aquifers (SJRGA 1999). 2.2.3 Regional Hydrogeology The facility is located in the northern portion of the Tracy Subbasin (subbasin 5-22.15) of the L San Joaquin Valley Groundwater Basin (DWR 2006). Water-bearing formations include (from oldest to youngest) the Tulare Formation, Older Alluvium, Flood Basin Deposits, and Younger Alluvium. The cumulative sediment thickness is up to 3,000 feet (DWR 2006). 1, The Tulare Formation consists of semi-consolidated, discontinuous deposits of clay, silt, and [ ' gravel. The widespread Corcoran Clay unit occurs near the top of the Tulare Formation, extending from the foothills eastward to about the San Joaquin River, and acts to confine the deeper aquifers (DWR 2006; DWR 1967). Many large-capacity wells are completed in units below the Corcoran Clay because of the higher yield and quality of the deeper water. Older Alluvium consists of loosely to moderately compacted sand, silt, and gravel, and is widely exposed between the Coast Range and the Delta. It is approximately 150 feet thick. Flood Basin Deposits are present in the northern two-thirds of the subbasin in the Delta region. Composed primarily of silt and clay with occasional gravel interbeds near present waterways, these deposits have a maximum thickness of about 1,400 feet. This unit generally does not yield significant quantities of water and the quality is generally low (DWR 2006; DWR 1967). Page 4 Hydrogeologic Investigation and Groundwater Sampling and Analysis Work Plan, Sutter Home Lodi Winery, Lodi, California g:4s 9rouplatl,nn�bb'AB`AB65W5.06}WerlwneN9 repa,talwb lack U"ft�planYext.