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steel USTs and associated product lines, installed in 1964, were replaced. All service station facilities, including USTs, sumps, hoists, and piping were removed in 1994 during station demolition. The site is currently paved and used for car sales. 1.2 Site Geology and Hydrogeology Soil beneath the site consists primarily of silty clay and discontinuous lenses of silt or clayey silt containing occasional, varying amounts of fine-grained sand. In general, soil encountered below approximately 6 to 10 feet below grade (fbg) is much stiffer than shallower soil. Soil borings advanced on the eastern boundary of the site exhibit greater amounts of silt, while borings on the western boundary contain mostly clay. Groundwater flow direction at the site is consistently to the northwest at a gradient between approximately 0.005 and 0.01. 1.3 Previous Environmental Work Environmental investigation of the site has been ongoing since 1994. To date, eight groundwater monitoring wells, two excavations, four vapor probes, and fifteen cone penetration test (CPT) soil borings have been completed (Figure 2). Soil gas sampling was performed at the site in 2009 and 2010. Groundwater beneath the site was monitored and sampled quarterly from 1995 to 2011, and semi- annually from 2011 to 2014 by wells MW-1 through MW-5, MW-6A, MW-6B, and MW-7, as well as the sump located near the car wash on the property immediately north of the site (2480 Tracy Boulevard). The sampling of all groundwater monitoring wells was discontinued in accordance with a SJCEHD directive letter dated September 5, 2014 (Attachment A). 2. Proposed Scope of Work GHD proposes advancing 3 soil borings (B-1 through B-3) in accordance with CRA's Work Plan and Work Plan Addendum, and advancing two additional soil borings (B-4 and B-5) to collect shallow soil samples in the vicinity of the former used-oil tank and soil samples outside of the hydrocarbon impacted area to establish background metals concentrations. Justification for each work location is discussed below: B-1 through B-3 — investigate current hydrocarbon concentrations in soil in the vicinity of the former gasoline USTs and dispenser islands for comparison to LTCP criteria. B-4 — investigate constituents of concern in the vicinity of the former used-oil UST and confirm historical hydrocarbon concentrations detected in sample VVX-8. B-5 — assess background metals concentrations. 6322770-RPT 24-WORK PLAN ADDENDUM docx SECOND ADDENDUM 2