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GSI Job No.: 140 I G S T 1 Issued: 15 November 2017 ENVIRONMENTAL 3.1 Site Setting, Description and History The Site is approximately 4.86 acres of commercial property located at 1762 West Hammer Lane, Stockton, California. The Site is owned by SGM, a general partner of Lincoln Properties, Ltd., which also is named as a PRP in the Order. Based on information gathered to date by SGM, it appears that dry cleaning operations in the 1744 West Hammer Lane space began in approximately June 1959 and continued until March 1982, when the dry cleaning business moved to the 1762 West Hammer Lane space. The 1744 West Hammer Lane tenant space is currently occupied by David's New York Style Pizza. As part of the move from the 1744 to 1762 tenant space, previous dry cleaning machines reportedly were removed and new cleaning equipment was installed. On-Site dry cleaning occurred until 1995, when all dry cleaning equipment was removed and the facility continued as a drop-off business only with dry cleaning performed at an off-Site facility. 3.2 Geology and Hydrogeology The Site is located within the Central Valley sub-section of the Great Valley geomorphic province (DWR, 2012). The Central Valley is an approximately 400-mile long by 50-mile wide northwest trending, asymmetrical structural trough. The Central Valley consists of marine and continental deposits derived from the Sierra Nevada Mountain Range and the Coast Range (CDM; 2001; SJCDPW, 2004). The Sierra Nevada Mountain Range to the east of the Central Valley is comprised of pre-Tertiary igneous and metamorphic rocks. The Coastal Range to the west of the Central Valley is comprised of pre-Tertiary and Tertiary semi-consolidated to consolidated marine sedimentary rocks (SJCDPW, 2004). Geology near the Site generally consists of unconsolidated alluvial and floodplain deposits of the Modesto Formation. The Modesto Formation consists of a heterogeneous mix of poorly sorted clay, silt, sand, and gravel with occasional beds of claystone, siltstone, sandstone, and conglomerate.These units are discontinuous and have considerable lateral and vertical variability (Geosyntec Consultants, 2012). Similar lithologies are described in drilling logs of domestic wells in the Site vicinity, which were provided to GSI by the Water Board, as well as soil boring logs from environmental investigations in the general Site vicinity. Typically, the subsurface around the Site consists of five hydrostratigraphic zones as defined in previous environmental investigations conducted in the vicinity of the Site (LFR, 1999; Geosyntec Consultants, 2012; Geosyntec Consultants, 2015). The zones are referred to as: A-Zone; A/B-Zone, B-Zone; B/C-Zone; and C-Zone. The A-Zone primarily consists of interbedded and/or alternating fine and coarse-grained layers from the ground surface to the top of the A/B-Zone, approximately 75-85 feet bgs. The saturated portion of the A-Zone generally ranges from 30 to 40 feet bgs to the top of the A/B-Zone. The A/B-Zone typically ranges between 10 to 30 feet in thickness and consists of dense clay and silt. This zone can act as an aquitard when present. The lithology of the B-Zone is similar to the A-Zone, but contains smaller percentages of coarse- grained sediment. The top of the B/C-Zone is encountered at approximately 145 feet bgs and generally ranges between 10 to 30 feet in thickness. The B/C-Zone consists primarily of hard,silty clay and appears to be laterally continuous. Similar to the A/B-Zone,the B/C-Zone potentially acts as an aquitard when present. The C-Zone consists of relatively thick, permeable, coarse-grained sediments from approximately 150 to 300 feet bgs. In general, water levels measured from wells within the A-, B-, and C-Zone suggest that there is not a dominant vertical flow direction between hydrostratigraphic units (LFR, 1999; Geosyntec Consultants, 2012; Geosyntec Consultants, 2015). Site Investigation Work Plan Park Woods Cleaners