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0/LDC CLOSURE PLAN REVIEW -2- 27 March 1990 <br /> - The excavation will be backfilled with an engineered fill material and capped with <br /> asphalt. Care must be taken to ensure that the fill material is clean. <br /> - The excavated soil will be disposed of at Forward Landfill , which is acceptable. <br /> CLOSURE OF MONITORING WELLS <br /> - You propose to discontinue ground water monitoring after the surface impoundment <br /> is closed. Even though the source of the contamination has been removed, we still <br /> need to look at the impact or potential impact on ground water. The closure plan <br /> states, on page 24, that "The data indicate that there has been negligible impact <br /> on the groundwater from the contaminated soil in the SI . " This conclusion may be <br /> premature and we cannot support it until all ground water monitoring data is <br /> supplied and reviewed. <br /> We have not received the quarterly monitoring report for January 1990 as well as <br /> the year-end summary of ground water data, which was due 1 March 1990. (According <br /> to Brian Pletcher from Remediation Services, Inc. , the reports should be sent this <br /> week. ) The data collected thus far is inconclusive, since the detection limit for <br /> nickel has been set at 0.05 mg/1 . We are formalizing a monitoring order, which you <br /> should receive shortly, that sets the minimum detection limit for nickel to 0.001 <br /> mg/1 . The monitoring order will also ensure prompt reporting of data. The <br /> monitoring wells should remain open until we clear up the ambiguity of the nickel <br /> and have sufficient data to show ground water is free of pollutants or at <br /> concentrations which will not effect beneficial uses. <br /> We look forward to working with you on the conclusion of this project. Please inform <br /> us of the changes in the schedule for implementing the closure plan. If you have any <br /> questions, please call me at (916) 361-5729. <br /> 0, —YX &,_ I <br /> JEAN McCUE <br /> Water Resource Control Engineer <br /> JEM:jm <br /> Enclosure <br /> cc+encl . : Ms. Linda Hogg, Toxic Substances Control Division, Sacramento <br /> Mr. Ron Valinoti , San Joaquin County Environmental Health, Stockton <br /> Mr. John Schweizer, Remediation Services, Pleasanton <br /> Mr. C. Curtis Carter, Overhead Door Company, Lodi <br />