SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Ms Margaret Lagorio, September 27, 2006 Page 2 SECOR understands and appreciates the concerns of the SJCEHD and the RWQCB regarding the potential for generating wastes with oxygen injection to facilitate enhanced biodegradation. However, based on SECOR's experience (including bench scale testing) this approach can be effectively employed without the need to generate Waste Discharge Requirements. SECOR will confirm the information required and submit it to SJCEHD and the RWQCB. SECOFTs Additional Assessment Report included hydraulic testing at wells MWCI% MW 2, and MW-3 and a feasibility analysis of groundwater extraction for MTBE remediation. This included pre- and post-extraction analysis of groundwater samples from along the center of the plume. A total of 5,422 gallons of groundwater was extracted during the constant-discharge pump tests, and a total of 3.4 gram. s:of MTBE were removed. These results suggest that groundwater extraction may not be a cost effective remedial approach, for the site. SECOR Will provide engineering-level estimated costs to corroborate this conclusion. SECOR reviewed the historical results of the groundwater monitoring and analytical program that includes, amongst other analytes, a full suiteof fuel oxygenates and the lead scavengers. With the exception of MTBE, none of the oxygenates or load scavengeis have been Idetectedi above method reporting limits in any of thesamples from any of the site Wells--in-eight or more-consecutive quarterly sampling events (excepting recently installed wells). SECOR maintains that the groundwater contaminant, plume has been well characterized, and respectfully,requests"that the fuel oxygenates (except MTBE) and lead stavengef§ be idiminited -or-reduced in the groundwater monitoring program. This will reduce overall site monitoring costs Without endangering the protection of the groundwater resource. SJCEHD requested a work plan for additional downgradient wells. Although samples from the downgradient wells MWO-2 and. M/11-11 have detectable concentrations of MTBE, they are below the maximum contaminant, limits._ The detected concentrations in these and in the other recently-installed wells (MW*Elj MW-9, and MW 10) have d,Isplayed stable to, .reducing trends (data through 2"d qtr 2006). These data suggest the MTBE plume has been adequately determined. Pending:the third quarter 2006 sampling results SECOR will formally present the data in the next quarterly monitoring report and request that the SJEHD reevaluate the need for additional downgradient wells. ZECOR called Ms. Lagorio of the SJCEHD on September 22,2006 to discuss the details of the additional requested information and verify the need for additional,offsite, downgradient monitoring wells. Ms Lagorio, was out of the office and to return on October 2, 2006. S,ECOR, spoke briefly with Mr. Nuel Henderson (designated point of contact) regarding the HArespdnse to 8-29-06 SJEHD Itr and wp submittal 2.doc.