SITE INFORMATION AND CORRESPONDENCE FILE 2

Home Browse Search

San Joaquin County Environmental Health Department DIRECTOR 600 East Main Street Donna Heron,REHS W: Stockton, California 95202-3029 PROGRAM COORDINATORS x. Margaret Lagorio, REHS Robert McClellon,REHS Website: www.sjgov.org/ehd Jeff Carruesco,REHS, RDI 60 Kasey Foley, REHS Phone: (209) 468-3420 Fax: (209) 464-0138 November 17, 2009 Mr. Michael D. & Ms. Sharon Olivarez 540 Scotts Ave. Stockton, CA 95203 Subject: Skips Service Station (former) LOP Case#:1038 300 S. California St. CUF#:8492 Stockton, CA 95203 GeoTracker ID#: T0607700605 The San Joaquin County Environmental Health Department (EHD) has reviewed Work Plan- HB-1, MW-10, & MW-11, dated October 27, 2009 submitted by Foothill Engineering. The plan was required in EHD correspondence dated March 5, 2009, to investigate the lateral extent of the contamination in the groundwater from the underground storage tank (LIST) formerly located onsite. The plan calls for installing one shallow hand auger boring (HB-1) for soil collection under a formerly unknown UST located across Lafayette Street to the north of the site. Additionally, two monitoring wells are proposed to be installed offsite, MW-11 to the northeast and MW-10 to the east, both with the screened interval from 45 feet below ground surface (' bgs) to 80' bgs (35 feet). Soil samples are proposed to be collected and analyzed for total petroleum hydrocarbons as gasoline (TPHg), methyl tertiary-butyl ether (MtBE), and 1,2-dichloroethane (DCA). The EHD has evaluated the proposal and has concluded that although necessary, the plan is inadequate and not approved as submitted, [H&S 25296.10(c)(3)]. A revision is required and is to address the following concerns: 1. The 35-foot length of screened interval is excessive and can not be allowed. Technical justification is required for a screened interval longer than 10 feet when installed on monitoring wells in the deeper permeable zones. If field data collected at the time of well installation indicates additional permeable zones are present that should be monitored, additional monitoring wells with 10-foot screened intervals maximum may be installed in the immediate area. (clustered) 2. The EHD has not directed you to investigate the offsite, formerly unknown and newly discovered LIST. The EHD has not been advised that this LIST is linked to your site and as such, cannot require you to investigate it. The plan to install a hand auger/soil boring (HB-1) under this LIST and collect soil samples will require a technical justification before the EHD can consider this boring necessary. The elevated concentrations of TPI-Ig detected in the groundwater samples from CPT-3 and CPT-6 northeast of this area appear to fit a pattern of migration from the even higher TPHg concentrations detected in onsite groundwater samples collected from CPT-1 and CPT-2.