SITE INFORMATION AND CORRESPONDENCE

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r 1 Z Ms.Lori Duncan November 15,2011 RE: 2911 E.Fremont St,Stockton,CA Page 2 of 14 Geology and Hydrogeology The subject site is located within the San Joaquin Valley, a broad structural trough bounded by the Sierra Nevada and Coast Ranges of California. The San Joaquin Valley,which comprises the southern portion of the Great Valley of California,has been filled with up to 30,000 feet of sedimentary deposits ranging in age from Jurassic to Holocene. Sediments in the eastern valley,derived from the erosion of the Sierra Nevada, have been deposited by major to minor west-flowing drainages and their tributaries. In general, these sediments consist of poorly cemented, interbedded sands,silts,and clays deposited as a result of lacustrine and fluvial processes associated with the San Joaquin River system. Based upon soil samples collected during drilling of boring LPB-1,which was drilled immediately adjacent to the former clarifier, soil beneath the site consists primarily of silt and clay from the ground surface to approximately 26 feet bgs,silty sand and sand with silt from approximately 26 feet to approximately 32.5 feet bgs,silt and clay from approximately 32.5 feet bgs to approximately 41 feet bgs, and silty sand to sand silt from approximately 41 feet bgs to approximately 42.5 feet bgs,where rod refusal was encountered. Samples collected from nearby soil borings suggest that the sand layer beginning at approximately 26 feet bgs varies in thickness from approximately 4 feet in boring LPB-2, located approximately 14 feet north of the former clarifier,to approximately 9.5 feet in boring LPB-3,located approximately 14 feet west of the former clarifier. No contaminants were detected in any samples collected from borings LPB-2 or LPB-3 Shallow groundwater beneath the site occurs at a depth of approximately 55 feet below ground surface(bgs). Regional groundwater flow in the area is highly influenced by large volume agricultural pumping and in the Stockton area is generally northeast, toward a large groundwater pumping depression northeast of Stockton. Previous Subsurface Investigations According to the Geotracker database,a previous occupant of the site(A&A Tool Rentals)utilized several underground fuel storage tanks(USTs),including a 550-gallon waste oil UST,a 550-gallon kerosene UST,a 2,000-gallon gasoline UST,a 2,000-gallon diesel UST, and a 3,000-gallon UST that alternately contained kerosene and gasoline. According to limited information provided by the San Joaquin County Environmental Health Department (EHD) the USTs were removed in 1992. WHF Environmental Consultants, Inc. conducted an over-excavation of the former 2,000-gallon USTs to remove impacted soil to a depth of approximately 17 feet and collected confirmation samples. The site was subsequently closed by EHD. Figure 2 shows the locations of the former USTs. Krazan & Associates, Inc. (Krazan) conducted a subsurface investigation at the site in April 2010 to investigate recognized environmental conditions identified in a previous Phase I Report. The subsurface investigation consisted of drilling and sampling ten soil borings throughout the property, including drilling three soil borings(B 1,B2,and 133)near the inactive wash rack/drain/clarifier area in the southern portion of the building. Soil samples collected from borings B2 and B3 contained petroleum hydrocarbons at depths of 10, 15,and 20 feet bgs. No samples were collected beneath 20 feet bgs. Lee& Pierce supervised the drilling and sampling of four additional soil borings(LPB-1 through LPB-4)near 10759-EXC SUMMARY LTR