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2.0 SITE DESCRIPTION AND BACKGROUND This section presents a description of the Site and background information. 2.1 Site Location and Description The Site is located at the intersection of West Main Street and North Locust Drive in Ripon (Figure 1). Investigation activities will be conducted in the vicinity of the former Ripon Cleaners,which operated until the mid-1990s. Currently,the former Ripon Cleaners building is occupied by Blessner's Tae Kwon Do.The Site is generally surrounded by commercial properties except for residences located to the north (Figure 2).Sewer,water, and electrical utilities are present within the Site vicinity,with laterals connecting to the commercial buildings. Ripon Cleaners is listed as a halogenated generator in the California Department of Toxic Substances Control (DTSC) Hazardous Waste Tracking System. On February 11, 2020, RWQCB spoke to the current property owners,who stated that Ripon Cleaners closed around 1993 to 1995.The owners could not recall which chemical(s) were used for dry cleaning nor how the chemical(s) were disposed (communication provided in the March 13, 2020, RWQCB Scope of Work). 2.2 Geology and Hydrogeology The City of Ripon lies within California's Central Valley, a northwest trending asymmetric trough bordered on the east by the Sierra Nevada Range and on the west by the Coast Ranges. The San Joaquin Valley comprises the portion of the Central Valley that lies southeast of the Sacramento-San Joaquin River Delta and is underlain by approximately 32,000 feet of Jurassic to Holocene sediments (AMEC Geomatrix, Inc. [AMEC] 2009). The Site is located within the low-lying eastern flank of the San Joaquin Valley, at the southern boundary of San Joaquin County. Based on hydrogeological studies by Nestle environmental contractors, the stratigraphic intervals of the Central Valley Aquifer system beneath the Site have been categorized as the Upper, Intermediate, and Lower Aquifers. Depth intervals for the hydrostratigraphic zones vary with location due to the gradual slope of the land and depositional surfaces. The Upper Aquifer has been divided into a shallower B zone and a deeper A zone.The Intermediate Aquifer is divided into a shallower C1 zone and a deeper C2 zone. The underlying Corcoran Clay Aquitard consists of green plastic clay and separates the Intermediate Aquifer from the Lower Aquifer(AMEC 2009; Haley and Aldrich 2020). The water table (B-zone) occurs at approximately 25 to 30 feet bgs in the vicinity of the Site and varies seasonally,with the highest elevation in the first half of the year and the lowest elevation generally in the fourth quarter (Haley and Aldrich 2020). Figure 4 shows the groundwater contours based on the Nestle data. In April and May 2020, the general groundwater flow direction in the Upper and Intermediate Aquifers is to the north-northwest(Haley and Aldrich 2020). FINAL RIPON PCE INVESTIGATION WORK PLAN.DOCX 2-1 PROJECT NO.631021512