SITE INFORMATION AND CORRESPONDENCE CASE 1

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s Former Western Lift July 19, 2012 3430 S. EI Dorado Street Page 2 of 2 The area of UST-4 was investigated. Soil contamination was encountered during boring advancements and MW installations. Ground water contamination (gasoline) from MW sample results was also documented. Ground water was monitored from 1992 through 2009 in the southern area of the Site. Ground water sample results declined in contaminant concentration from 1992 through 2009. The only contaminant reported in 2009 was MTBE from MW-1 at a concentration of 1.2 ug/L and all the other MWs were below laboratory detection reporting limits. EHD staff and Central Valley Water Quality Control Board (CVRWQCB) staff agreed that the southern area had completed the required investigation and corrective action/cleanup. No further action was required by letter dated 5 January 2010. for the southern area of the Site. All MWs in the southern area were destroyed,-but MWs and remediation wells in the northern area were retained and the Site remained open and in remediation. A soil vapor extraction and insitu ground water air sparging (SVE/IAS) remediation system was installed in the northern area and is currently in operation. -Active remediation is underway in the area of former UST-4 and soil vapor and ground water contaminant concentrations are declining. The SWRCB Division of Financial Assistance has recommended that the EHD review the above referenced underground storage tank Site for closure. Please discontinue active remediation immediately. After an appropriate period of time; perform soil vapor and ground water sampling for rebound testing and cleanup verification. Ifmthe soil vapor and ground water rebound test sample results do not exhibit an appreciable increase in contaminant concentration, the Site can be evaluated for closure. If warranted, a case closure summary and a no further action required (NFAR) request must be submitted to the EHD and the CVRWQCB. The report must include: soil and ground water plume delineation; a predictive model of plume behavior without active remediation; a soil vapor intrusion evaluation; a human health risk assessment; An estimate oh the residual contaminant mass in soil and ground water; the time it will take to achieve ground water quality objectives (WQO); and all other appropriate closure criteria. If you have any further questions`regarding this matter, please contact Harlin Knoll at (209) 468- 3442. Harlin Knoll, REHS Nuel C. Henderson, Jr., PG Senior Registered Environmental Health'Specialist Engineering Geologist cc: James Barton, CVRWQCB, 11020 Sun Center Drive, #200, Rancho Cordova, CA 95 670 GeoPhase Environmental, 2937 Veneman, #13240, Modesto CA 95356 Underground.Storage Tank Cleanup.Fund, State Water Resources Control Board, P.O. Box 944212, Sacramento, CA 94244-2120