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If contamination is remaining, describe concentration range and volume (cubic yards or meters) <br /> �� • '-,,Some soil contamination is remaining near monitoring wells MW3 MWS and MW6 TPH as diesel <br /> ` ND-28 m Ik TPHasgasg1ineND-l30mg/kg Volume unknown <br /> r <br /> ' Table III - Maximum documented contaminant concentrations in soil before and after cleanup <br /> Method Before AfterDepth Method Before After Depth <br /> Contaminant used (mg/kg) (mg/kg) (ft) Contaminant used (mg/kg) (mg/kg) (ft) <br /> Excavation Excavation ND NO 1075 <br /> TPH (Gas) 22 NO 10 75 Benzene <br /> Excavation Toluene Excavation ND NO 10 75 <br /> TPH (Diesel) 120 95 10 5 <br /> Other fuel Ethylbenzene Excavation NO NO 10 75 <br /> (TOG) <br /> Heavy metals Xylene Excavation 0 010 NO 1075 <br /> (Zinc) <br /> Other Other <br /> IV. Groundwater Remediation Information <br /> Groundwater remediation method(s) None <br /> Volume treated and/or removed None <br /> If contamination is remaining, describe concentration range and volume (gallons or liters) Diesel ND- <br /> 4 0 mg/L Gasoline ND-14 0 mg/L Benzene ND-5 3 ma/L This contamination is likely the result <br /> of operations from adjacent sites Volume unknown <br /> Table IV - Maximum documented contaminant concentrations in groundwater <br /> . before and after cleanup <br /> Method Before After Depth Method Before After Depth <br /> Contaminant used (mg/L) (mg/L) (ft) Contaminant used (mg1L) (mg/L) (ft) <br /> TPH (Gas) - 4 0 Benzene 5 3 <br /> TPH (Diesel) - 140 - Toluene 042 <br /> Other fuel Ethylbenzene 1 9 <br /> Heavy metals Xylene 26 <br /> Other 1,2- 002 Other— <br /> dichloroethene <br /> V. Closure <br /> Does Regional Board concur with closure? Yes ✓ No <br /> Rationale for closure_l Based on current data the sail and groundwater contamination due to <br /> underground storage tank (UST) operations at the Unocal site have been remediated 2) The residual <br /> petroleum contamination occasionally detected in Unocal well MW3 is likely the result of operations at <br /> the adjacent site Well MW3 is side gradient from the former UST locations at.Unocal and down <br /> gradient from the operations at the adjacent site 3) The chlorinated and petroleum hydrocarbon <br /> contamination in Unocal well MW5 is likely caused by other adjacent terminal operations This well is <br /> closer to 12jezometers and monitoring wells installed on ad acent sites and quite distant from the former <br /> Unocal UST locations In addition ] 2-dichloroethane was only detected in Unocal well MW5 and not <br /> In other Unocal wells <br /> Location of reports on file (Agency/Room) <br /> County Staft person Phone <br /> Regional Board office Sacramento Staff person P S isorena Phone (916) 255-3049 <br />