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28 February 2006 AGE-NC Project No. 06-1390 Page 2 of 6 The Modesto, Riverbank and Turlock Lake Formations and overlying Recent alluvium are the principal sources of domestic ground water in the 13,500-square mile San Joaquin Valley Ground Water Basin(Basin 5-22).The estimated depth to ground water at the site is approximately 20 to 25 feet below surface grade(bsg)based on information from Lines of Equal Depth of Water Wells Fall 1999,published by the San Joaquin County Flood Control District and Water Conservation District- FCD&WCD. The general ground water flow generally toward the east/northeast.However,this may be greatly modified by local recharge and discharge patterns. 2.2. UNDERGROUND STORAGE TANK REMOVAL A 10,000-gallon underground storage tank(UST)was removed from the property on 28 July 1993; at the time of removal,the tank was listed as containing diesel fuel, installation date unknown(the property shop/warehouse was constructed in 1975). Two samples from beneath the tank and a composite sample from the stockpile were analyzed for diesel, motor oil and BTEX (benzene, toluene,ethyl-benzene and total xylenes).The results ofthe analyses reported non-detect for samples collected from beneath the tank and reported a detection of 67 parts per million of diesel in the stockpile sample. The excavation was filled with clean soil and the stockpile was spread over the surrounding field to remediate the low level TPH-diesel impact. A no further action(closure)letter was issued by the EHD for the tank removal on 23 December 1994. During file review on 16 February 2006 at the EHD,AGE found a letter dated 03 January 1986 from Eugene Marion of Slakey Brothers to the EHD stating that "We have converted our 10,000 gallon gasoline storage tank to diesel as of January 3, 1986". Because the tank was thought to have only contained diesel fuel, no testing was performed during the tank removal for gasoline, lead or additives like methyl tertiary-butyl ether (MTBE) and 1,2-dichloroethane(1,2-DCA);the tank could be assumed to contain gasoline from as early as 1975 to January 1986. 3.0. SCOPE OF WORK AGE proposes to advance one soil boring for the collection of soil and grab ground water samples, to determine if petroleum hydrocarbon and/or fuel-oxygenating compounds have impacted soil and/or ground water beneath the site.The limited phase II site assessment will include the following tasks: • Permitting and pre-field work activities; • Soil and grab ground water sample collection and analysis; Advanced GeoEnvironmental,Inc.