SITE INFORMATION AND CORRESPONDENCE

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� WN/ ..i Gail Wiggett August 14. 1996 Page 2 i chromatograms for the five groundwater samples collected at the Site in June 1996 for the presence of MTBE. Superior reported that their review of the chromatograms docs not indicate the presence of MTBE in any of the .five collected groundwater samples. However,this could not be validated since the samples were not analyzed and confirmed with an MTBE Standard. .SECOR will include MTBE as an analyte for the third quarter 1996 groundwater monitoring event. If the laboratory analytical reports do not indicate concentrations of MTBE,we feel it would be unnecessary to continue analvsis of MTBE. Monitoring for Dissolved Lead In accordance with Monitoring and Reporting Program No. 95-902,dissolved lead was analyzed in groundwater samples collected from wells MW-I, MW-2,. MW-4, and MW-5 in June 1994. Dissolved lead was not reported above the laboratory reporting limit in these samples with the exception of 9.4 pg/Q reported in the sample collected from well MW-2. A letter dated January 17, 1995 from the RWQCB for the Site stated that"Based on these results. lead testing in these MWs is no longer needed. When free product in MW-3 has been completely removed,it and any MW subsequently installed shall be tested for dissolved lead." In May 1995, a growidwater sample collected from well MW-3 was analyzed for dissolved lead as reported in the second quarter 1995 monitoring report: dissolved lead was not detected above the laboratory_ reporting limit. Based on this information,dissolved lead is no longer monitored. Proposed Additional Monitoring Parameters for Biological Activity The release of oxygen from the ORC Filter Socks in wells MW-2, MW-3_ and MW-4 does not appear to be effective in reducing petroleum hydrocarbon concentrations in the vicinity of these wells since their installation in November 1995. The manufacturer of the ORC Filter Socks indicated that the perforniance of the Filter Socks may be overshadowed by the higher hydrocarbon concentrations associated with the rise in groundwater levels. Competition for oxygen demand may also be occurring between the hydrocarbon-oxidizing bacteria and the peaty, organic-rich soil beneath the Site. The manufacturer also indicated that the typical six month oxygen release period for the ORC Socks has been exceeded. Therefore,.SZCO/l plans to remove the ORC Filter Socks from these wells in July 1996 as discussed in a July 9, 1996 telephone conversation with you. 5'li('O/l conducted additional analysis for biological activity during the June 1996 groundwater monitoring event to evaluate if subsurface conditions at the Site are favorable for effective biodegradation. Groundwater samples collected from wells MW-) and MW-5 were analyzed for hydrocarbon-oxidizing microbial populations and additional bioparameters: a discussion of these analyses is included in the attached Quarterly Groundwater Monitoring Report. Second Quarter 1996. Need for Consideration of Alternative or Additional Remedial Measures You requested. by August 15. 1996, a schedule of proposed tasks and completion dates for a feasibility study — examining remedial alternatives for the Site, and implementation of alternative or additional corrective action. In a September 21. 1994 letter from Mr. Phil Isorena of the RWQCB to Mr. Harry Crockett of Real Estate Asset Specialists (the court appointed receiver for the Site) the RWQCB recognized that it was not feasible to it nn�nitt�:atisti:ra