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• __ ENVIRONAENTAL HEALTH L-EPARTMENT <br /> OPp'U!NC <br /> SAN JOAQUIN COUNTY <br /> Q` �` Donna K. Heran, R.E.H.S. Program Coordinators <br /> Director 304 East Weber Avenue,Third Floor Carl Borgman, R.E.H.S. <br /> s.� Laurie A. Cotulla, R.E.H.S. Stockton,California 95202-2708 Mike Huggins, R.E.H.S., R.D.I. <br /> Cq'• .a�? <br /> c - Assistant Director Telephone: (209)468-3420 <br /> Margaret Lagorio, R.E.H.S. <br /> ,F o <br /> Robert McClellon, R.E.H.S. <br /> Fax: (209)464-0138 .Teff Carruesco, R.E.H.S. <br /> Website:www.sjgov.org/ehd/ Kasey Foley, R.E.H.S. <br /> LOLLY BOZZANO 'JUL 31 2DD6 <br /> 2891 ARATA RD <br /> STOCKTON CA 95215 <br /> RE: Three Palms Grocery SITE CODE: 1830 <br /> 6732 Hwy 88 <br /> Stockton, CA <br /> San Joaquin County Environmental Health Department (EHD) has reviewed "Summary of <br /> Additional Subsurface Investigation and Vapor Extraction Testing Report" (Investigation Report) <br /> dated June 22, 2006, and "First Quarter 2006 Groundwater Monitoring Report" (Monitoring <br /> Report) dated July 21, 2006, prepared by ATC Associates Inc. for the above referenced site. <br /> The reports contain information about the installation of monitoring wells MW4 and MW5 <br /> (screen interval 130 to 140 feet) that have screen intervals below first water, installation of vapor <br /> extraction wells VW1, VW2 and VW3 (screen interval 15 to 45 feet), the conduction of vapor <br /> extraction tests and the results of water samples from the monitoring wells. <br /> The Investigation Report recommends preparation of a Corrective Action Plan (CAP) and states <br /> that soil vapor extraction appears to be a viable method for remediating the TPHg and BTEX <br /> impacted soil at the site. The contaminant concentrations in the vapor samples collected during <br /> the vapor extraction tests are low. The results of the contaminant concentrations in the soil <br /> collected from the site indicate that the area of contaminated soil existing is limited to below the <br /> former underground storage tanks (UST's) and the dispenser island with the highest <br /> contaminant concentrations found at 25.5 feet below surface in the former UST area. The <br /> Investigation Report also states that "to accelerate clean-up completion intervals should be <br /> targeted and limited" and that the "radius of influence should be further evaluated" after <br /> installation of a vapor extraction system. Prior to preparation of a CAP or installation of a vapor <br /> extraction system, further investigation of the effectiveness of vapor extraction at the site should <br /> be conducted. Installation of an additional vapor extraction well with a limited screen interval in <br /> the most contaminated area may optimize the removal of the contaminants. Periodic vapor <br /> extraction as performed at other sites may be more cost effective than installing a permanent <br /> system. <br /> The Monitoring Report recommends continued quarterly groundwater monitoring and sampling <br /> of MW 1 through MW5 and the domestic well. Quarterly monitoring of the wells at the site will <br /> continue to be required by EHD. The Monitoring Report also recommends installation of an <br /> additional deep-screened monitoring well to the north of MW5 and VW2, but provides no <br /> justification for installation of the well. The initial water sample from MW5 had a detection of 1,2 <br /> DCA, but the second sample from MW5 was non-detect for 1,2 DCA. Toluene and xylene were <br /> detected in both samples from MW5 at low concentrations. If site data can justify installation of <br /> another deep-screened monitoring well, then it should be provided in a work plan for installation <br /> of an additional well. <br />