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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:  Record of Decision
ROD ID:  EPA/ROD/R08-94/081
ROD Date:  04/07/1994
Operable Unit(s):  04
Media:  Groundwater, surface water
Contaminant:  LNAPLs, VOCs, SVOCs, pesticides, metals, sulfones
Abstract:  Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.

The Sand Creek Industrial site is located in the both Commerce City and Denver, Colorado. The site is bound to the north by Interstate 270, on the south by East 48th Avenue, and on the east by Ivy St. and the eastern section of the 48th and Holly Landfill. The western boundary is approximated by Colorado Boulevard, Vasquez Boulevard, and Dahlia St. Land use near the site is primarily industrial and includes trucking firms, petroleum refining operations, chemical production and supply companies, warehouses, and small businesses. Several other Superfund sites are also located in the area, including the Rocky Mountain Arsenal, Chemical Sales Company, and Woodbury Chemical sites. Properties adjacent to the site are zoned for light and heavy industrial uses, industrial park, industrial park storage, and agricultural uses. Fifteen residences housing approximately 25 people are located within a one-mile radius of the site. The daytime population reaches several hundred due to local businesses and the industrial nature of the area.

Four known sources of contamination are located on-site and are currently inactive: the Colorado Organic Chemical Company (COCC) property, the 48th and Holly Landfill, the L.C. Corporation (LCC) property, and the Oriental Refinery property. Operable Unit (OU) 4 of Sand Creek Industrial addresses groundwater affected by these four sources and is the focus of this ROD.

Municipal water for the area surrounding OU4 is supplied by the South Adams County Water and Sanitation District (SACWSD) and the Denver Water Department (DWD). Groundwater produced from alluvial beds and bedrock wells north of I-270 is a major source of water supplied by SACWSD. Water supplied by the DWD is obtained primarily from surface water sources located outside of the site area. Three discrete alluvial aquifers (Aquifers 0, 1, and 2) have been identified. The extensive amount of clay material present in the subsurface at the site tends to inhibit groundwater flow and contaminant migration. The direction of groundwater flow in Aquifers 0 and 2 is generally consistent with the regional flow direction of the alluvial system. The only surface water feature within the site is a 1-acre wetland that is fed by a subsurface drain system and is located immediately north of the landfill.

The COCC plant originally manufactured pesticides in the 1950s under the name of Times Chemical. The site has been the scene of two fires in 1968 and 1977. After these fires, several health agencies found unacceptable conditions at the plant including unsatisfactory waste management practices, unsatisfactory worker safety conditions, violations in storage and handling of flammable liquids; and soil containing high levels of thermally altered pesticides and other chemicals. In 1977, the Colorado Department of Health ordered all operations to cease at the COCC site.

Waste disposal operations at the 48th and Holly landfill were conducted from 1968 to 1975, during which the landfill accepted both demolition and domestic refuse. In 1977, two combustible gas explosions were traced to the migration of methane gas from the landfill. After the landfill ceased operations in 1975, the site was covered with between 1 and 10 feet of sandy soil, and revegetated. In 1991, and active gas extraction system was installed for OUs 3 and 6.

The LCC property has been part of Commerce City industry since 1948. Between 1948 and 1958, part of the property was used as a gravel quarry. LCC was to line its spent acidic waste disposal pits with an impermeable film prior to disposal. The liner was installed, but was breached after acidic wastes were disposed of in the LCC pits. In 1980, LCC used lime to neutralize the pits and filled them with clean backfill.

The Oriental Refinery property was located in the northwest corner of 52nd and Dahlia and was destroyed by fire in 1955. As a result, approximately 48,000 gallons of refined petroleum products may have been released from storage tanks. Plant operations and the fire have resulted in groundwater contamination.

During the early 1980s a variety of contamination was discovered at the site by EPA's Field Investigation Team (FIT). The contamination was produced by at least four sources: the COCC facility, the LCC property, the Oriental Refinery site, and the 48th and Holly Landfill. Between 1985 and 1990, RI/FS operations were conducted at the site as part of the Sand Creek Superfund studies. During 1991 and 1992, approximately 2,000 cubic yards of debris were removed by a licensed hauler and disposed of in permitted landfills. Soil vapor extraction (SVE) operations began at COCC to remove volatile organic compounds (VOCs) from the soil at l (OU1). Low temperature thermal treatment was selected as a method for cleaning up soils contaminated with pesticides and metals at the COCC in OU5. Remediation of OUs 1 and 5 is expected to be completed in 1994.

In order to address contamination, EPA has divided this site into six operable units (OUs). Operable units 1,2,3,5, and 6 have completed Records of Decision (ROD) to address site threats. The first ROD was written in 1988 for OU 1. The OU4 study area is the focus of this ROD and consists of the underlying groundwater. OU4 also includes the light non-aqueous phase liquid (LNAPL) plume floating on the water table beneath a portion of the site. EPA included LNAPLs in OU4 despite the general exclusion of petroleum from CERCLA investigations because the product is mixed with hazardous substances, the presence of hydrocarbons in the subsurface adversely affects SVE remediation at OU1, and the LNAPL provides a continuous source of dissolved-phase contaminants to groundwater. Contaminants detected in the groundwater include VOCs, SVOCs, pesticides, metals, and sulfones.
Remedy:  The selected remedial action for this site includes monitoring of groundwater and surface water for a period of 30 years; implementing institutional controls including deed, zoning, and municipal water supply restrictions; removing LNAPLs using a dual vapor extraction (DVE) system which combines liquids extraction, volatilization, and biodegradation; discharging water from an oil/water separator to an on-site treatment facility where it will be treated using chemical precipitation, sedimentation, air stripping (with off-gas treatment using a thermal or catalytic oxidation unit); recovering LNAPLs with off-site recycling; using liquid phase granular activated carbon (GAC) for final treatement; and regenerating spent GAC.
Text:  View full-text ROD [ 100K ]
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