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To: Mike Baker, COPA Re: Comments on the EE/CA for WTTP, Final Draft February 1998 Prepared for EPA by Earth Tech This Engineering Evaluation and Cost Analysis (EE/CA) report for the Winston Thomas Treatment Plant (WTTP) in Bloomington, Indiana was prepared by Earth Tech, under contract to EPA. The objective is to examine alternative approaches for cleaning up some of the PCB-contaminated material at the site. The WTTP is an abandoned wastewater treatment plant owned and maintained by the City of Bloomington. A Westinghouse capacitor manufacturing plant discharged PCBs to the WTTP from 1958 until the early 1980s (Powell 1986). All components of the WTTP were contaminated by PCBs: sludge drying lagoons, sludge drying beds, four digesters, a trickling filter, settling basins, piping, buildings, on-site and off-site soil. This EE/CA report addresses remediation of three areas of the site (referred to as "units"): 1. The abandoned lagoons ( abandoned sludge drying lagoons, total area approximately 1 acre, presently vegetated) 2. The tertiary lagoon (17 acres, 2 to 3 feet of water present year-round, surrounded by earthen berm, with several feet of sludge and clay under the water) 3. The trickling filter (approximately 584,000 cubic feet of crushed limestone in a below-ground concrete basin) Other areas of the site that have PCB-contamination (digesters, piping, the interim storage facility) are being addressed separately by the consent decree parties. Following evaluation of several remedial alternatives, the EE/CA report proposes the following: excavation, sludge and sediment dewatering, disposal of material with more than 50 ppm PCBs at an off-site TSCA landfill, disposal of material with 15 to 50 ppm PCBs at an off-site special waste landfill, water treatment if necessary prior to discharge to Dillman Road treatment plant, on-site cleaning of tricking filter rocks with on-site placement of cleaned rocks, and verification sampling to ensure that the cleanup objectives are achieved. Comments Cleanup Criteria Soil, sludge and sediment will be excavated (or treated in-situ) until the average PCB concentration remaining does not exceed 15 ppm. No more than 25 ppm PCBs is allowed to remain in any location sampled. Although it is not specifically mentioned in the report, this excavation criteria should apply to surface soil and soil at depth. The residual surface PCB concentration in areas with sensitive ecological receptors (e.g., wetlands, floodplains, erodible soils) is not allowed to exceed 1 ppm PCBs. The report states that the 1 ppm cleanup level applies to the area of the abandoned lagoons, but it does not specify that it applies o the tertiary lagoon or erodible surface soil that would discharge to Clear Creek. It is proposed that this 1 ppm residual concentration may be achieved by a) covering contaminated soil with clean fill and vegetation, or b) eliminating the wetland conditions. The lower cleanup goal should be applied to all lagoon areas, including the tertiary lagoon, and should include all surface soil that is potentially erodible. Eliminating wetlands is not an acceptable method of wetland remediation. The lower cleanup goal was established to protect sensitive ecological receptors. Removing the sensitive receptors and their habitat in order to avoid a more stringent cleanup goal should not be accepted. Risk Evaluation The basis for the proposed cleanup criteria is a "focused" risk evaluation. The 15 ppm PCB criteria was determined to be protective of human health (for construction workers and site maintenance workers), and the 1 ppm PCB criteria was determined to provide adequate ecological protection. SENES Oak Ridge has reviewed risk-based cleanup criteria proposed for the WTTP and Lemon Lane Landfill by Westinghouse, EPA and other parties and they have expressed serious concerns with the methods used and pathways analyzed. They concluded that because the risk analyses do not address uncertainty and variability, the results might be misleading. In addition, because all potential routes of exposure and exposure scenarios are not included the proposed cleanup criteria may not be protective of human health or the environment. They further state that "a more detailed investigation of legitimate pathways of concern is needed and uncertainty estimates should be included before this analysis would be scientifically defensible", particularly when the consequence of a misleading result will be costly. Copies of SENES Oak Ridge's comment letters are available from COPA. Tertiary Lagoon Dewatering It is proposed to drain the Tertiary Lagoon and discharge the water to the City of Bloomington's Dillman Road treatment plant. The report estimates that 10 percent of the water will require treatment with carbon prior to discharge to the Dillman Road plant. Alternatives for water treatment are not identified. Carbon is an acceptable treatment method, but there may be more effective or less expensive water treatment processes available. Saturated Sludge and Sediment The report asserts that saturated sludge and sediment will be processed with an "appropriate" sludge dewatering system without describing one or identifying alternatives. These will be the most highly contaminated media encountered during remediation, with PCB concentrations measured as high as 5,700 ppm. One alternative process for destroying PCBs in saturated sediment and sludge is identified in the EE/CA as a "secondary" remedial process (steam extraction/electrochemical peroxidation), but it is not retained for evaluation. The failure to examine alternative processes for removal, dewatering and treatment of saturated sediment and sludge is a serious deficiency of the EE/CA. Airborne PCBs Methods to prevent airborne transport of PCBs during remediation must be identified and evaluated. This is recognized as an important mechanism for PCB transport, and it is not acceptable to assert that wind erosion and volatilization will be controlled without examining the specific methods available to do so. Land Disposal The discussions of implementability, effectiveness and cost for land disposal are much too general, particularly since land disposal features in every alternative proposed. Promising treatment processes are scrutinized in great detail, and landfill operators should be held to the same high standards. A demonstrated ability to meet permit conditions is essential, and convincing proof that the PCBs will be contained for as long as they remain a threat is very important. Treatment Processes This EE/CA examined several thermal treatment processes widely accepted as effective for treating soil contaminated with PCBs, but the focus should have been on technologies with experience treating sewage sludge and saturated sediment. More effort should have been made to seek out and evaluate treatment processes based on their ability to treat saturated or dewatered sludge and sediment. PCB Test Kits The data contained in Appendix G of the EE/CA shows that the PCB field test kits can be an acceptably accurate screening tool for a cleanup criteria of 15 ppm PCBs. However, the test kits are less reliable as the PCB cleanup goal is increased. The test kits would be totally unreliable for higher cleanup goals. For example, the data in Appendix G indicates that if a cleanup goal of 100 ppm were applied, the field test kits would only identify half of the samples that actually contain 100 ppm or more based on lab analysis. This should be kept in mind if field test kits are proposed for hot spot delineation. |
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