Risk Management Plan
I. EXECUTIVE SUMMARY
The Dutch Boy site (Site) is located in south-central Chicago, Illinois. Historically, the Site was used for lead-related operations that have resulted in lead contamination of surface and subsurface soils. Approximately 75% of the 5-acre Site is paved with reinforced concrete and is underlain by extensive utility infrastructure, for which no records exist. The USEPA conducted a risk assessment for the Site and developed a cleanup goal of 1,400 mg/kg lead under an industrial future land use scenario. This Risk Management Plan presents and evaluates remedial scenarios to mitigate and manage the risks posed by lead contamination present in Site soils at concentrations above this threshold. An investigation of the Site was conducted, during which thirty five boreholes were installed in the unpaved areas. Lead was detected in concentrations above the 1,400 mg/kg threshold in most of these boreholes. The depth of contamination exceeding the threshold was generally two feet or less, although in some boreholes contamination extended down to seven feet below ground. The total volume of soil exceeding the threshold is approximately 4,500 yd3. Limited lead contamination was encountered under some of the paved sections of the Site. However, the existing pavement prevents access, adequately containing the lead. Thus, remedial options were considered to address exposed soils in the unpaved areas of the Site. Technologies and remedial scenarios available to mitigate and manage the risks posed by this lead contamination include separation of the lead from the soil matrix, immobilization of the lead within the soil matrix, and containment of the soil and lead. These technologies were evaluated for protectiveness of human health and the environment and cost effectiveness. In addition, the appropriateness of the technology or remedial strategy for application at the Site was considered and used as a preliminary filter. The most appropriate technologies were engineering/institutional controls through containment of the Site with a compacted soil cover and stabilization and solidification of the contaminated soil matrix, which immobilizes the lead. Disposal of treated soil off-Site at a RCRA Subtitle C landfill was also considered. Combinations of these technologies were all determined to be protective of human health and the environment and ranged in cost from approximately $750,000 to $1,600,000. Alternatives considered included (1) a soil cover over the unpaved areas of the Site, (2) removal of the top two feet of soil in the principal threat waste area and a soil cover over the unpaved areas, (3) removal of the top two feet of soil in the unpaved areas, and (4) removal of all soil with lead concentrations greater than the 1,400 mg/kg threshold. Table ES-1 presents a summary of the alternatives evaluated. The most cost effective protective remedy was determined to be removal and off-Site disposal of the top two feet of soil in the principal threat waste area in the vicinity of the loading dock, backfilling, and containment of the remaining unpaved area soil with a compacted, vegetated soil cover. This approach is consistent with provisions of the Administrative Order directing remediation of the Site. This strategy is protective of human health and the environment in that it removes soil with the highest concentrations of lead and prevents exposure to the remaining lead-impacted soil. Although not the lowest cost alternative, it is the most cost- effective in terms of removing principal threat wastes and maintaining the overall protectiveness of the remedy. This alternative is estimated to cost approximately $940,000.
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