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Wendy L. Cohen • • <br /> 6 1 December 1994 <br /> 27. Pages 7-1 and 7-2, Recommendations <br /> Comment: I concur with the recommendations. In addition, the STTC also should define the <br /> extent of contamination in the C-zone and D-zone, and confirm the hydropunch sample results <br /> by installing MWs. <br /> 13 October 1994 Letter <br /> This letter compares total lead results from the hydropunch and MW sampling. The unfiltered <br /> hydropunch samples ranged from 17 ,ug/l to 320 t49/1. The filtered MW results had less than 5 kg/1 <br /> to 8 ug/l. EMCON concludes that the hydropunch results are anomalously high due to unfiltered <br /> samples. I concur with EMCON's conclusion. <br /> 14 October 1994 Letter <br /> This letter transmitted a schedule only for the implementation of the work plan for the air sparging <br /> trench pilot study. However, in a meeting on 21 September 1994, Mr. Thun told us that EMCOa <br /> has prepared a feasibiliy study (FS) work plan, the FS work plan would be discussed at the 4 <br /> October 1994 STTC meeting, and a time schedule outlining the status of on-going tasks and <br /> implementation dates of future tasks would be submitted to us. Therefore, the 14 October 1994 <br /> schedule is incomplete. <br /> Summary <br /> 1. Contamination in the C-zone and D-zone is not defined. <br /> 2. The extent of contamiraticn in the A-zone and B-zone is defined. However, the hydropunch <br /> sample results which helped define the extent of contamination in these zones need to be <br /> confirmed by installing ground water MWs. EMCON's proposed MWs IA, 1B, 2A, 3A, 513, <br /> 613, 7B, and 8B must be installed to verify the hydropunch sample results and establish the <br /> limits of contamination in the A-zone and B-zone. <br /> 3. EMCON has not conducted the air sparging trench pilot study. <br /> 4. There is no schedule for submittal of the FS work plan. <br /> PSI:psi/lsb <br />