SITE INFORMATION AND CORRESPONDENCE FILE 2

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PUBLIC HtALTH SERVICtS SAN JOAQUIN COUNTY ENVIRONMENTAL HEALTH DIVISION ` Karen Furst, M.D., M.P.H., Health Officer 304 East Weber Avenue, Third Floor • Stockton, CA 95202 209/468-3420 NOV 0 2 2000 DAVID J CAMILLE SCOTT T HOOTON TOSCO MARKETING COMPANY BP OIL COMPANY 2000 CROW CANYON PLACE STE 400 295 41 ST SW SAN RAMON CA 94583 RENTON WA 98055 RE: TOSCO/BP Service Station# 11192 SITE CODE: 1995123 1403 Country Club Blvd. RO#:0000087 Stockton,C.A.,95204 San Joaquin County Public Health Services,Environmental Health Division(PHS-EHD) has reviewed the "Proposed Groundwater Purging and Disposal at Tosco (former BP Oil# 11192)" dated October 17,2000 as submitted by Gettler-Ryan Inc (GRI) on October 20,2000 and has the following comments. This proposal is a response by GRI to PHS-EHD October 3,2000 correspondence that required clarification to the intent and specifics of the"pump and disposal' of petroleum contaminated groundwater at the above referenced site. This most recent proposal has clarified the intent of this proposed action as an"interim remedial action" and established the duration for six-months on a weekly groundwater extraction of 5,000 gallons from monitoring well#3. PHS-EHD has not directed Tosco/BP to conduct an interim redial action,but due to recent rises in the MtBE in all monitoring wells onsite,this proposal complies with acceptable methods to reduce the mass and migration of the contaminant. Under Step 3 within the SWRCB Guiddires for lnzestigationand Cora p cfMtBE and other Oxygenates (Guidelines) final draft dated 30 March 2000,sites with persistent concentrations of MtBE over 10,000 ppb should have those concentrations and mass reduced before the plume can spread. But the Guidelines report does not specify the method or duration of the remedial action,nor does it specify a recommended volume for the method you have chosen. In addition,the Guidelines report emphasizes the importance of identifying the source of the MtBE release in the subsurface. Tosco/BP have made no mention of the status of their investigation as to the potential source of the increasing groundwater MtBE contamination since July 1998. MtBE groundwater concentrations in MW-7 were at 200 ppb until July 1998. Subsequent quarterly monitoring and sampling events indicate increasingly elevated concentrations of MtBE in both MW-7 and MW-3. The most recent sampling event submitted to PHS-EHD for the event held on July 14,2000 indicates that MW-3 has MtBE at 120,000 ppb and MW-7 has MtBE at 55,000 ppb. MtBE has been detected in all of the monitoring wells since mid to late July 1995,with the exception of MW- 5. Until it can be determined that your proposal to pump and dispose of MtBE contaminated groundwater is effective in reducing the contaminant mass,PHS-EHD imposes the following conditions on the proposal. 1) The weekly pumping of 5,000 gallons from MW-3 is approved,but for only two(2) month instead of the six requested. Brief reports/status updates which contain EPA Method 8260B analytical data for MtBE in the pre-pumped and post-pumped MW-3,as well as pumping rates and disposal records for the groundwater are to be submitted to PHS-EHD weekly. A Division of San Joaquin County Health Care Services