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TreadweIEMlo <br /> Groundwater samples were obtained from Borings CSB-1 through CSB-4 All the groundwater <br /> samples contained concentrations of petroleum hydrocarbons quantified as TPH-d Relatively <br /> low concentrations of TPH-d were detected in Borings CSB-1 and CSB-4 at 130 and 290 gg/L, <br /> ' respectively Bonng CSB-3 had concentrations of petroleum hydrocarbons quantified as TPH-g <br /> and TPH-d at 12,000 and 580 µg/L, respectively Boring CSB-2 had concentrations of <br /> ' petroleum hydrocarbons quantified as TPH-g and TPH-d at 34,000 and 440,000 4g/L <br /> respectively No benzene was detected in any groundwater samples, while toluene, <br /> ethylbenzene, and xylenes were detected at Boring CBS-2 at 260, 2,500, and 7,100 µg/L, <br /> respectively Low levels of additional volatile organics were detected at CSB-2, CSB-3, and <br /> CSB-4 Tables 1 and 2 summarize the analytical results of Treadwell &Rollo's investigation for <br /> soil and groundwater, respectively <br /> 4.0 SITE REMEDIATION <br /> 4.1 Proposed Remediation <br /> ' The 12 April 2004 Soil and Groundwater Investigation, Carando Site (Treadwell &Rollo, <br /> 2004a)presented a proposal to excavate contaminated soil and pump out contaminated <br /> groundwater at the former UST locations The proposed excavation was 43' long by 14' wide by <br /> 23' deep as shown on Figure 2 (Figure 2 illustrates a 25-foot depth following workplan approval <br /> conditions )The excavation dimensions were chosen to remove the majority of the identified <br /> saturated and vadose zone soil contamination, and enable removal of most of the contaminated <br /> ' groundwater Because the excavation required shoring on all four sides, the dimensions could <br /> not be modified once the shoring was in place, and the excavation work began Additionally, the <br /> ' sheet pile shoring prevents collection of sidewall samples <br /> ' The proposed excavation would account for approximately 512 cubic yards or 820 tons of soil, <br /> and it was estimated that approximately 18,000 to 36,000 gallons of contaminated groundwater <br /> would be removed <br /> ' 25971020 DGD 4 23 August 2004 <br />