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A total of six bottom samples (including one duplicate) were collected during the excavation activities; however, two of these samples were subsequently superseded either due to elevated concentrations of the constituents of concern (SPCC-B-2-1) or because the excavation needed to be vertically expanded to accommodate the SPCC construction (SPCC-B-3-1). These two samples were replaced by subsequent bottom confirmation samples SPCC-B-2A-2 and SPCC-B- 3A-2, respectively. Bottom samples were collected at a rate of one sample per approximately every 625 square feet(i.e., every 25-foot by 25-foot area). Confirmation samples were analyzed on a 24-hour turnaround time to avoid project delays and were analyzed for PAHs using EPA Method 8310, for TPH-g, TPH-d, and TPH-mo using EPA Method 8015M, and for heavy metals using EPA Method 6010/7000 series. Results from the confirmation samples were compared to the DTSC approved preliminary screening criteria for the Site to determine whether or not additional excavation was required. These preliminary screening criteria are as follows: ■ 0.9 mg/kg maximum B(a)P equivalent concentration; ■ 100 mg/kg for TPH-g; ■ 500 mg/kg for TPH-d; ■ 1,000 mg/kg for TPH-mo; and ■ Concentrations similar to background levels for metals. These preliminary screening criteria are considered conservative and the presence of these chemicals at or below the screening criteria are expected to be fully protective of human health and/or the environment. Analytical results for PAHs, expressed as B(a)P equivalents, in the confirmation samples showed elevated concentrations in only one sample (SPCC-B-2-1 at a concentration of 2.05558 mg/kg); however, this sample was removed via excavation and a subsequent confirmation sample (SPCC-B-2A-2), collected in the same location at a deeper depth after the additional excavation was complete, exhibited a B(a)P equivalent concentration of 0.008415 mg/kg. This sample along with all other confirmation samples showed no exceedances of the 0.9 mg/kg B(a)P equivalent screening criteria. Detected B(a)P equivalent concentrations in the remaining 16 confirmation samples ranged from 0.002974 mg/kg in Sample SPCC-B-2A-2DUP to 0.338029 mg/kg in Sample SPCC-W-11-2DUP. Analytical results for TPH showed no detections of TPH-g in any of the confirmation samples collected. In addition, TPH-d and TPH-mo concentrations were all below the preliminary screening criteria for the Site. As previously stated, Samples SPCC-B-2-1 and SPCC-B-3-1 were superseded and replaced with Samples SPCC-B-2A-2 and SPCC-B-3A-2, respectively. Results from the subsequent samples showed no detections of TPH-g, TPH-d, and/or TPH-mo. Title 22 Metals concentrations in the confirmation samples collected as part of the SPCC excavation operations showed detections for the following metals: antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, nickel, selenium, vanadium and zinc. The number of constituents and the concentrations detected in the confirmation samples were similar to background samples collected during the Remedial Investigation conducted at the Site. Typical metals constituents of concern at MGP sites include arsenic and lead. Results for arsenic in the 16 remaining confirmation samples collected during the SPCC excavation ranged from PARSONS 42 FINAL RI REPORT-FORMER TRACY MGP APRIL 2010