SITE INFORMATION AND CORRESPONDENCE

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O/LDC INSPECTION• -3- 7 June 1990 Mr. Forrest Canutt, from Bay Area Tank and Marine Environmental Technologies, arrived on site just before I left. He is the contractor that will pump out the water in the impoundment and remove the remaining contaminated soil . Mr. Lingard stated that he would like to start the work 1 May 1990. Mr. Pletcher and Mr. Canutt agreed to that target date. INSPECTION SUMMARY Upon review of the historical monitoring data in our files, it appears that nickel has not been detected in any of the monitoring wells since October 1987 (except for a single occurrence in MW-1 of 0.05 mg/l in January 1989) . Arsenic and lead continue to be detectable at very low concentrations (µg/1 ) in all wells. Nitrates have been detected in concentrations above the drinking water standard of 45 mg/l in wells MW-1, MW-2, and MW-5. TDS is elevated in wells MW-1 and MW-2. Chromium concentrations in MW-1 have been above detection limits since the beginning of ground water monitoring, in December 1985. In addition, chromium has been above the drinking water standard of 0.05 mg/l in MW-1 on several occasions: 0.08 mg/l in December 1985, 0.07 mg/l in June 1986, and 0.08 to 0. 13 mg/l since March 1989. Since December 1986, chromium in MW-2 has been above detection limits more than fifty percent of the time. Concentrations in MW-2 have ranged 0.01 to 0.04 mg/l , with one occurrence of 0.07 mg/1 in March 1989. Chromium has been detected twice in MW-3: 0.0069 mg/l in October 1989 and 0.005 mg/l in April 1990. Samples collected from MW-4 and MW-6 have not contained chromium concentrations above detection limits, which ranged from 0.05 to 0.005 mg/l . Chromium was detected in MW-5 on only two occasions: 0.019 mg/l in October 1989 and 0.006 mg/l in April 1990. It appears that MW-1 and MW-2 have been impacted. Ground water monitoring should continue in accordance with monitoring Order No. 90-903. `,FC,/"-,I-K" AN McCUE Water Resource Control Engineer JEM:jm