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(.� U <br /> San Joaquin County DIRECTOR <br /> 1' Donna Heran,REHS <br /> Environmental Health Department OL h ASSISTANT DIRECTOR <br /> Q f 600 East Main Street Laurie cornua,REHS <br /> Stockton' California 95202-3029 <br /> r ` PROGRAM COORDINATORS <br /> Carl Borgman, REHS <br /> Website: wwwMike Huggins,REHS,RDI <br /> FOR sjgov.org/end - Margaret Lagorio,REHS <br /> Phone: (209)468.3420 Robert McClellon,REHS <br /> Fax: (209)464-0138 Jeff Carruesco,REHS, RDI <br /> Kasey Foley, REHS <br /> March 11, 2009 <br /> Adrienne Rishwain <br /> Transamerica MT Associates <br /> 2800 W. March Lane, #360 <br /> Stockton, CA 95219 <br /> Subject: Contaminated groundwater beneath 2800 W. March Lane, Stockton, CA <br /> The San Joaquin County Environmental Health Department (EHD) provides regulatory oversight <br /> of the contamination from unauthorized releases of,petroleum from underground storage tanks <br /> (USTs). The investigation and clean up of a release from former USTs at 2701 W. March Lane, <br /> Stockton, has been on-going since 1995. Three monitoring wells (MW-9S,91,9D) were placed in <br /> front of the northeast corner of your property in 1999 to monitor the plume of contaminated <br /> groundwater at the 2701 W. March Lane site. <br /> The water samples from MW-9S, 91, 9D had no detections of contaminants until March 2007.- . <br /> The contaminant detected was MTBE. Since that time the concentrations of MTBE in the water <br /> samples from those wells has risen to as high as 160 micrograms/liter or parts per billion and <br /> currently is about 100 parts per billion: The secondary maximum contaminant level for MTBE in <br /> public drinking water is 5 parts per billion. The plume of contaminated water is migrating with <br /> the flow of groundwater which is to the southwest. Therefore,the plume of contaminated water <br /> may have migrated to beneath your building. 4 <br /> The EHD directed the active responsible party, ConocoPhillips, to define the extent of the A <br /> contaminated groundwater and approved of the performing of interim groundwater extraction <br /> from MW-9S, 91, 9D to cleanup and control the migrating groundwater contamination. In order <br /> to comply with the EHD's directive, ConocoPhillips proposed and the EHD approved of <br /> installation of three monitoring wells southwest of the Placer Title building. ConocoPhilips <br /> informed the EHD that,you have not been willing to grant access to your property for installation <br /> of the monitoring wells or groundwater extraction activities. . <br /> The EHD has informed Conoco Phillips that if Transamerica MT Associates will not allow the <br /> installation of monitoring wells, an alternative investigation of obtaining grab water samples from <br /> soil borings could be proposed. .Monitoring wells are preferred because you can obtain samples <br /> over time and have the ability to continually monitor the plume. If the plume of contaminated <br /> groundwater is beneath the Placer Title building, the risk of vapors intruding into the building <br /> should be evaluated since the depth to water is about six feet below surface. Access to your <br /> property is necessary to investigate the extent of migration of the plume of-MTBE and decide if <br /> vapor intrusion into your building has to be evaluated. <br /> i <br />