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Record of Decision System (RODS)



Address:  33RD AND DAHLIA 
City & State:  COMMERCE CITY  CO  80022
County:  ADAMS
EPA ID:  COD980717953
EPA Region:  08
NPL Status:  Deleted from the Final NPL
ROD Type:  Amendment
ROD ID:  EPA/AMD/R08-93/074
ROD Date:  09/08/1993
Operable Unit(s):  05
Media:  Soil
Contaminant:  Organics, Metals
Abstract:  The Sand Creek Industrial (Operable Unit 5) site, a former pesticide manufacturing facility, is part of the 550-acre Sand Creek Industrial site located within the Sand Creek floodplain in Commerce City, Colorado. The site surface is composed principally of alluvial materials and imported fill, which covers the area so that natural features are difficult to discern. Surficial fill materials at the site consist of clay, silt, sand, gravel, and debris including concrete, brick, wood, metal, plastic, glass, and trash. Land use in the area is predominantly industrial and residential, with some agricultural. The estimated 25 people who reside within a one-mile radius of the site use production wells to the north and downgradient of the site, ground water, and surface water fromalluvial and bedrock wells to obtain their drinking water supply. The Sand Creek Industrial site lies in the vicinity of three other Superfund sites: Woodbury Chemical, Chemical Sales, and Rocky Mountain Arsenal. Four suspected contaminant source areas were identified at the Sand Creek Industrial site: the Oriental Refinery, the Colorado Organic Chemical Company (COC) facility, the 48th and Holly Landfill, and the L.C. Corporation property; the COC facility is the focus of this action. Beginning in the 1960s, the COC manufactured pesticides onsite. Disposal and onsite storage areas include a landfill and acid pits. Onsite fires in 1968 and 1977, as well as improper pesticide storage practices, resulted in pesticide-contaminated soil, ground water, and surface water. In 1978, COC removed some contaminated soil, and in 1984, COC removed drummed wastes, excess product, and additional contaminated soil; and implemented site access restrictions, including fencing. The Sand Creek Industrial site was divided into six OUs to facilitate remediation. A 1989 ROD addressed OU1, which included remediating the most highly contaminated soil and some of the subsurface soil within the COC area. A 1990 ROD addressed source control of the remaining surface soil in the COC area through excavation of 14,000 yd[3] of contaminated soil, soil washing, incineration, backfilling, and grading and revegetation of the site, as OU5; however, the remedial action was not implemented because new technical data and cost information obtained during the Remedial Design phase determined that soil washing would not reduce the contamination to the cleanup levels, and the cost of this treatment would be three to four times greater than originally estimated in the ROD. In 1991, the U.S. Army Corps of Engineers (USACE) conducted a bench-scale treatability study to evaluate the effectiveness of soil washing for the removal of pesticides. Results of these tests were inconclusive since the soil samples used in the study did not containcontaminant concentrations above action levels. In 1992, EPA and State studies indicated that soil washing could reduce pesticide concentrations in the soil, but could not achieve the action levels established in the 1990 ROD. This ROD amendment provides a final source remedy for the contaminated soil present onsite at the COC area, as OU5. Other 1993 RODs address contaminated soil, ground water, surface water, and air contamination, as OUs 2, 3, and 6. The primary contaminants of concern affecting the soil are organics, including pesticides; and metals, including arsenic and chromium.

SELECTED REMEDIAL ACTION: The amended remedial action for this site includes excavating and treating 8,000 yd[3] of contaminated soil onsite to a depth of 5 feet, using low-temperature thermal treatment (LTTT) to volatilize the pesticides and arsenic; collecting volatilized contaminants on GAC; transporting spent activated carbon offsite for regeneration; backfilling and revegetating the excavated area with the treated soil; and conducting treatability studies. The estimated present worth cost for this remedial action is $5,422,782.

PERFORMANCE STANDARDS OR GOALS: Chemical-specific soil cleanup goals are based upon health riskbased action levels, and include aldrin 1.45 mg/kg; arsenic 12.7 mg/kg; alphaBHC 3.91 mg/kg; beta-BHC 13.7 mg/kg; gamma-BHC 18.9 mg/kg; chlordane 18.9 mg/kg; chromium 56.2 mg/kg; DDD 104 mg/kg; DDE 73.2 mg/kg; DDT 72.4 mg/kg; dieldrin 1.54 mg/kg; heptachlor 5.47 mg/kg; heptachlor E 2.71 mg/kg; and toxaphene 22.4 mg/kg. This list includes new action levels for arsenic, dieldrin, heptachlor, and other pesticides. These levels are more comprehensive than those established in the 1990 ROD; however, the levels for heptachlor and dieldrin are less stringent based on recent EPA guidance.

Remedy:  The new selected remedy for OU5 addresses shallow soils contaminated with pesticides and metals in the Colorado Organic Chemical Company area at the Sand Creek Industrial Site. The major components of the September 1990 ROD were excavation and soil washing treatment of contaminated shallow soils, incineration of soil wash residuals, backfilling of the treated soils, and grading and revegetation of the site. Based on new technical data and cost information obtained subsequent to the September 1990 ROD, EPA has reconsidered its decision to employ soil washing and incineration of the generated residuals as a source control measure for OU5. New data evaluated by EPA included technical data on contaminant removal efficiency via soil washing and cost information for incineration received during the remedial design for OU5. Other components of the September 1990 ROD are not affected by this new information.

The new remedial action selected by EPA for OU5 involves treatment of the contaminated soils and includes the following principal components:
. Excavation of contaminated soils and treatment in an onsite low-temperature thermal treatment (LTTT) facility,
. Off-site treatment (regeneration) of spent activated carbon, and
. Backfilling of excavated areas with treated soil and revegetation of the site to minimize erosion and dust emissions.
Text:  View full-text ROD [ 471K ]
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