SITE INFORMATION AND CORRESPONDENCE FILE 1

Home Browse Search

San Joaquin County DIRFcroR Donna Heran,REHS PQ�'N Environmental Health .Department ASSISTANTDIRECTOR fi00 East Main Street Laurie Cotulla,REHS W. Stockton, California 95202-3029` PROGRAM COORDINATORS Carl Borgman, REHS ?' Mike Huggins,REHS,RDI Website: WWW.Sjg0v.org/ehd Margaret Lagorio,REHS � Phone: (209) 468.3420 Robert McClellon, RENS Fax: (209) 464-0138 .teff Carruesco, REHS,RDI Kasey Foley,REHS 02 April 2008 Messrs. Robert Trommer, CHG, and Kirk Larson, PG State Water Resources Control Board Division of Financial Assistance 1001 1 Street Sacramento CA 95814 Subject: Preliminary Five-Year Review of Claim Number 51 103 E Street Stockton, California San Joaquin County Environmental Health Department (EHD) has received and reviewed Preliminary 5-Year Review Summary Report for Claim Number 51; Site Address. 103 E Street 26 March 2008 in wh ich. ou recommend site closure North 'Stockton CA 5- r review) dated Y I { Y i consideration. Among the criteria cited to justify the site closure recommendation was the i following conclusion: • The plume size is stable and sufficiently delineated in lateral and vertical extent and contaminant concentrations detected in groundwater show a decreasing trend with time . j The EHD. believes that the site is approaching an appropriate point for closure consideration and is anxious to close:the site; however, as noted in the 5-yr review, the highest and most recent: 1:,2-DCA concentration detected was 63 micrograms per liter (pg/.I). This is the only monitoring event data from the newly installed monitoring well MW-17. Groundwater samples from new monitoring wells MW-15 and MW-18 were also impacted by 1,2-DCA, the sample from MVV-16 did not contain detectable a concentration of 1,2-DCA. With only one monitoring event conducted on MW-17, a concentration trend cannot be demonstrated for that well. The EHD. agrees that the vertical. extent of groundwater impacted by 1,2-DCA has. been delineated by analytical data from grab groundwater samples collected from CPT-1, CPT-2, CPT-4, CPT-5, CPT-10, CPT-12 and CPT-13., but the EHD does not believe that the lateral extent of 1,2-DCA-impacted groundwater has been defined in the downgradient direction, generally toward the east-southeast to the south-southeast. Intuitively, the 1,2-DCA concentrations in the MW-17 sample do not seem that high and the mass would seem to be quite small, but the concentration is three orders of magnitude above the MCL. The site data and the. location of MW-17 equally support interpretations that the 63 pg/l 1,2-DCA is the remnant of the leading edge of the-plume or that it is part of the trailing edge of a large detached plume. The former case seems the more likely,, but neither can be demonstrated at this time. The EHD would not present the current data to the Central Valley Regional Water Quality Control Board (CVRWQCB) and expect concurrence with your conclusion noted above. The EHD's experience indicates that the CVRWQCB would note the data issues cited above and not concur with a closure recommendation; it has also been the EHD's experience that the CVRWQCB requires a higher degree of plume delineation for 1,2- Site 51 Preliminary Five-Year Review Comment Letter 0408.doc I