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Record of Decision System (RODS)

MIDCO II

Abstract

Site Name:  MIDCO II
Address:  5900 INDUSTRIAL HIGHWAY 
City & State:  GARY  IN  46406
County:  LAKE
 
EPA ID:  IND980679559
EPA Region:  05
 
NPL Status:  Currently on the Final NPL
 
ROD Type:  Amendment
ROD ID:  EPA/AMD/R05-92/193
ROD Date:  04/13/1992
Operable Unit(s):  01
 
Media:  Soil Sediments, Ground Water
 
Contaminant:  VOCs Metals Inorganics
 
Abstract:  SITE HISTORY/DESCRIPTION: The 7-acre MIDCO II site is an abandoned chemical waste storage and disposal facility in Gary, Indiana. Land use in the surrounding area is predominantly industrial. The underlying aquifer, which is used primarily for non-drinking purposes, is highly susceptible to contamination from surface sources. From 1976 to 1978, this site was used for treatment, storage, and disposal of chemical and bulk liquid wastes. Onsite pits were used for disposal, from which wastes percolated into and contaminated the ground water. An overflow pipe from a filter bed disposal pit discharged directly into a ditch draining directly into the nearby Grand Calumet River. Additionally, an estimated 10 waste storage tanks were deteriorated and leaking. In 1977, a fire at the site destroyed an estimated 50,000 to 60,000 waste drums. In 1981, EPAinstalled a fence around the site. From 1984 to 1989, EPA removed all surface wastes, including thousands of drums and numerous tanks of chemical waste; excavated and disposed offsite subsurface soils and wastes from the sludge pits and the filter bed; and extended the site fence. This ROD amends a 1989 ROD that addressed the remaining contaminated soil, pit wastes, and ground water by treatment of an estimated 35,000 cubic yards of soil wastes using solidification/stabilization followed by onsite disposal; excavation and solidification/stabilization of 500 cubic yards of contaminated sediments followed by onsite disposal; covering the site in accordance with RCRA landfill closure requirements; ground water pumping and injection into a shallow or deep aquifer with or without treatment, depending on treatment studies; and implementing deed and access restrictions. The amended remedy reduces the estimated amount of soil to be treated, as a result of amended soil CALs and a determination that arsenic may not be present above background levels. The primary contaminants of concern affecting the subsurface soil, sediment, and ground water are VOCs, including toluene, TCE, and xylenes; metals, including chromium and lead; and inorganics. PERFORMANCE STANDARDS OR GOALS: Ground water clean-up standards are not changed from the 1989 ROD. Treatment required prior to OU1 are further defined compared to the 1989 ROD, and include at a minimum treatment to MACs, which are required for RCRA delisting. Specific MACs include methylene chloride 31.5 ug/l; trichloroethene 31.5 ug/l; toluene 6,300 ug/l; chromium 630 ug/l; nickel 630 ug/l; and lead 99.5 ug/l. Treatment below the MACs will be required if necessary to protect underground sources of drinking water. Soil treatment action levels are increased from 1x10[-6] and HI = 1 in the 1989 ROD to 5x10[-4] and HI = 5 in this ROD. INSTITUTIONAL CONTROLS: Institutional controls including deed and access restrictions will be implemented to protect the integrity of the site cover and operational aspects of the remedy.
 
Remedy:  SELECTED REMEDIAL ACTION: The amended remedial action for this site includes reducing the amount of soil to be treated from an estimated 35,000 cubic yards to an estimated 12,200 cubic yards; excavating and treating the contaminated soil onsite using soil vapor extraction, followed by in-situ solidification/ stabilization; excavating an estimated 500 cubic yards of contaminated sediment from a ditch adjacent to the northeast boundary of the site, with onsite solidification/stabilization; pumping and onsite treatment of contaminated ground water using air stripping and carbon adsorption, or possibly precipitation, with deep well injection of the treated water; constructing a final vegetated RCRA cover over the entire site; implementing institutional controls including deed restrictions, and site access restrictions; conducting long-term monitoring and providing for a contingency remedy if clean-up action levels for the Calumet Aquifer are technically impracticable to attain which includes low-level pumping to contain contaminated ground water and additional institutional controls. The ground water treatment or underground injection portions of this remedy may be combined with remedial actions for the adjacent Midco I site. The estimated present worth cost for this amended remedial action is $13,000,000, which includes an annual O&M cost of $660,000.
 
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