SITE INFORMATION AND CORRESPONDENCE FILE 2

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A%W N#014 Letter Of 9-13-91 1. The last two quarterly reports have indicated a TPHg of <.50 ppb due to a clerical error. The original lab report showing 58 ppb is correct. 2. All future reports and proposals will include a letter of acknowledgment. 3. We believe that we have identified the lateral and vertical extents of contamination. I think that the results of BH-1 are being reviewed with the results from MW 9, 10, 11. Again, BH-1 is related to another tank 600' away. 4. The site was determined clean in the Phase I1 Investigation Report dated 7-7-90, except for 1 ppb of benzene in Monitor Well 11. Therefore, a Problem Assessment Report was not considered necessary. 5. The disposal of well water will be handled as discussed in the response to the letter of 10-10-90, part 4. 6. Please find the boring location and boring log in this package. BH-1 was installed on 3-27- 90 with Greg Lyon present and backfilled with concrete the same day. 1. We believe that Monitor Wells 9, 10, 11 are properly located at or near the boundary of any possible contamination. The monitor wells are showing benzene as less than .5 ppb to 1.7 ppb. Even though the gradient changes direction from northeast to southeast, we are still able to monitor any changes in benzene levels. Also, Monitor Well 12 was installed in the same direction as Monitor Well S. On 6-7-91 there was no BTX found in Monitor Well 12. 2. Again, the TPHd that you refer to is related to BH-1, which is related to another tank 600' away. In regards to future sampling events: 1. Elder Engineering will be using a reel to retrieve the bailer from the wells. 2. Elder Engineering will confirm all sampling dates 48 hours in advance with Steve Schneider by phone and fax. 3. After five sampling events, Monitor Wells 9, 10, 11 are clean except for a trace of benzene in Monitor Well 9 & 11. However, even for this well 3 out of the five tests showed benzene to be below an action level. Therefore, we believe that closure of Monitor Wells 9, 10, 11 are in order if the next sampling event shows benzene below an action level.