SITE INFORMATION AND CORRESPONDENCE

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v •.� San Joaquin County PQU"� Environmental Health Department DIRECTOR Donna Heran,REHS 600 East Main Street Stockton, California 95202-3029 PROGRAM COORDINATORS Robert McClellon, REHS �= Jeff Carruesco, REHS,RDI Website: www.sjgov.org/ehd Kasey Foley,REHS Phone: (209) 468-3420 Fax: (209)464-0138 July 30, 2010 Ms. Mary E. Sanchez 1633 W Walnut Street Stockton CA 95203 Subject: Former UST LOP Case#: 1844 1876 Country Club Blvd. CUF#: 1026 Stockton, CA 95203 Global ID#: T0607700260 The San Joaquin County Environmental Health Department (EHD) has reviewed Case Closure Review for Sanchez Property (Review) dated June 2, 2010, by Western Geo-Engineers (WEGE) and has the following comments. This document was submitted to the EHD in preparation for submitting a No Further Action Request (NFAR) report. Groundwater remediation (groundwater pump and treat) has been in progress at this site since April 2005, and reports submitted to the EHD have included laboratory data that indicates this remedial action, in addition to excavation and disposal of the contaminated soil action in February 2003, have significantly reduced the dissolved petroleum hydrocarbon concentrations in the groundwater. Initial dissolved concentrations of total petroleum hydrocarbons as gasoline (TPHg) in 2002 were at 54,000 micrograms per liter (ug/1). During the last sampling event, March 16, 2010, the TPHg groundwater concentration was reported at 3,200 ug/l. Similar reductions were noted in other monitoring wells in and around the former underground storage tank (UST) area for other dissolved petroleum hydrocarbons. As of March 2010, dissolved TPHg and xylenes in samples from two monitoring wells, MW-10 and MW-6A, were the only constituents of concern (COC) with concentrations that exceeded water quality objectives (WQOs) and San Francisco Bay Regional Water Quality Control Board (SFBRWQCB), Environmental Screening Levels (ESL). It was noted in the Review that a soil gas sampling collection survey was planned and that the groundwater pumping was suspended. The EHD concurs that a soil gas survey should be conducted. The results of the soil gas survey can be included in the NFAR. Please submit a work plan that details the methods, materials, and locations of the soil vapor probes and a Well Permit Application Form and $366 fee per parcel and a $122 fee per probe in a timely manner. Public Works encroachments or a private parcel access agreement is needed for offsite vapor probe installations. Probes left in place overnight are considered a vapor well and are to have a surface seal and traffic box installed. A well destruction permit is needed prior to removing vapor wells.