Laserfiche WebLink
EPCV. <br /> • t� %�� HEAL" 111 ENSR International <br /> *M P—MIT SFRV GE 14411 Old Placerville Road <br /> Suite 210 <br /> 03 DEC -- ! PPS 1: 04 Sacramento,CA 95827-2508 <br /> (916)362-7100 <br /> FAX (916)362-8100 <br /> r <br /> www.ensr.com <br />= November 26, 2003 <br /> Ms. Margaret Lagorio <br /> County of San Joaquin <br /> Environmental Health Department <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202-2708 <br /> RE: Evaluation of 1,2-Dichloroethane in Groundwater and Proposed Changes to the <br /> Monitoring and Sampling Program - Former Unocal Facility #2859 <br /> 1665 Pacific Avenue, Stockton, CA <br /> ENSR Project Number 06940-357— Site Code 1213 <br /> Dear Ms. Lagono: <br /> On behalf of the Union Oil Company of California (Unocal), ENSR International (ENSR) has <br /> prepared this work plan for proposed evaluation of 1,2-Dichlorethane (1,2-DCA) in response to <br /> the San Joaquin County Environmental Health Department's letter dated July 31, 2003. A 90- <br /> day extension for submitting this work plan was granted to ENSR on September 26, 2003. <br /> Proposed Evaluation <br /> To evaluate the site as a potential source of 1,2-DCA in groundwater, ENSR proposes that j <br /> quarterly groundwater samples collected from wells MW-1 through MW-10 be analyzed for 1,2- <br /> DCA using EPA Method 8260. The analysis for 1,2-DCA is proposed for a period of one year <br /> or four consecutive sampling events beginning with the fourth quarter 2003 sampling event. <br /> Following the evaluation, ENSR will recommend appropriate actions. <br /> Additionally, ENSR requests the following changes to the current groundwater monitoring and <br /> reporting program for this site: <br /> 1. Discontinue groundwater sample analyses of methyl tertiary butyl ether (MTBE), tert butyl <br /> alcohol (TBA), di-isopropyl ether DIPS ethyl tertiary butyl ether ETBE and tertiary amyl <br /> methyl ether (TAME) using EPA Method 8260 in wells MW-12 through MW-19. <br /> 2. Discontinue groundwater sample analyses of 1,2 DCA and ethylene dibromide using EPA <br /> Method 8260 in wells MW-12 through MW-16. <br /> a <br /> J:1Projects1069401357-28591WorkinglCorrespondence106940-357.ALt.112603.doc <br /> 75 Years of Excellence in Environmental Services <br />