SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

San Joaquin County DIRECTOR Donna Hera RENS ASSISTANT Department DIRECTOR Z i 2 600 East Main Street Laurie Cotulla,REHS ": :{ Stockton, California 95202-3029 PROGRAM COORDINATORS >, Mike Huggins,REHS,RDI c•. _�- p Margaret Lagorio, REHS qui F�Rci\ Website: www.sjgov.org/ehd Robert McClellon,REHS Phone: (209) 468-3420 ,teff Carruesco, REHS,RDI Fax: (209)464-0138 Kasey Foley,REHS June 8, 2009 Stephanie Furgal Sergio Morescalchi Chevron Environmental Management Company Atlantic Richfield Company 6001 Bollinger Canyon Road Room K2240 PO Box 1257 San Ramon, CA 94583 San Ramon, CA 94583 Subject: Chevron #9-4275 and ARCO #2133 CUF Claim # CP0034 2905 & 2908 Ben Holt Drive Stockton, CA 95207 San Joaquin County Environmental Health Department (EHD) has reviewed Quarterly Groundwater Monitoring Report First Quarter 2009 (Report) dated May 29, 2009, submitted on your behalf by Stantec Consulting Corporation (Stantec) and has the following comments. The Report documents the results of a routine quarterly groundwater monitoring and sampling event that was performed at the above referenced contaminated underground storage tank co-mingled plume site on January 8-9, 2009. Analytical results were consistent with historical data in reporting low levels of contamination in the groundwater across the Chevron site to the north, and high concentrations centered around monitoring well E-10 on the ARCO site to the south. In the Report Stantec proposes the reduction of sampling of wells MW-1R, MW-3R, MW-6, MW-7R, MW-8, MW-9R and MW-10, (all installed as part of the Chevron site investigation) from a quarterly to an semi-annual schedule. The State Water Resources Control Board (SWRCB) has directed all sites consider switching to a semi-annual schedule of groundwater monitoring and sampling. The EHD recommends all wells on the Chevron side of the site be sampled on an annual schedule, with the exception of wells MW-2 and MW-5R which should be sampled on a semi-annual schedule. The EHD further recommends reductions in the analytical regimen of the Chevron wells. All wells should be analyzed for methyl tertiary butyl ether (MtBE). Wells MW-2R, MW-5R and MW-9R should also be analyzed for total petroleum hydrocarbons as gasoline (TPHg) and tertiary butyl alcohol (TBA), and well MW-6 should also be analyzed for TPHg. The EHD recommends all wells on the ARCO site be switched to an annual sampling schedule except wells E-3, E-4, E-6, E-9 and E-10, which should be sampled on a semi- annual schedule. All ARCO wells should be analyzed for TPHg and MtBE; well E-10 should also be analyzed for benzene, toluene, ethylbenzene, xylenes and TBA.