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rCALIFORNIA LIFORNIAGEORGE DEUKMEJIAN,Governor REGIONAL WATER QUALITY CONTROL BOARD—L VALLEY REGION 3443 ROUER ROAD SACRAMENTO,CA 95827-3098 27 March 1990 Mr. Alan R. Bashor Dallas Corporation 6750 LBJ Freeway -- 75240 P.O. Box 809046 Dallas, TX 75380-9046 FINAL CLOSURE PLAN REVIEW FOR DALLAS CORPORATION; DBA OVERHEAD/LORI DOOR COMPANY, SAN JOAQUIN COUNTY We reviewed your 30 January 1990 final closure plan for the surface impoundment at the Overhead/Lodi Door Company (0/LDC) facility, in Lodi . The closure plan appears to be adequate for the protection of ground water quality. Our comments on the plan are as follows: TIME SCHEDULE The time schedule (pg. 34) states that implementation of the closure plan will commence the first week of March, 1990. This schedule should be updated. EXCAVATION - We assume that there is still water in the impoundment from the winter season, which must be removed prior to excavation. Where will the water be pumped to and how will it be disposed? - The excavation and confirmation sampling plan is acceptable. It should be noted, however, that the closure plan is inconsistent in the description of the northwest corner of the impoundment. We do not agree with the conclusion that the concentrations of nickel in soil boring SB-20 (Table FCP-6) are at naturally occurring levels. On page 21, increasing nickel concentrations with depth in SB- 20 are dismissed as simply variations in soil type "since there is no evidence of a transport mechanism for contamination to reach these lower soils, and nickel occurs naturally in the native soil . . . " . Conversely, in the description of the "cemented zone" on page 4, the plan states "Soil investigations indicate that the Cemented Zone was effective in stopping the vertical migration of waste, with the exception of the northwest corner of the SI. " (emphasis added) The "cemented zone" is above the samples in question in boring SB-20 and there is evidence that waste constituents from the surface impoundment have reached ground water. Therefore, it cannot be concluded that a transport mechanism for contaminants to reach these lower soils does not exist. However, we feel that the soils remaining in the northwest corner after excavation, as proposed in the closure plan, will not pose a significant threat to ground water quality. Potential for further migration will be limited by backfilling and placing a cap over the impoundment. All final levels of nickel and zinc left in place, as determined by confirmation sampling, are subject to final approval .