Site Project Managers
Shaun Cwick, P.G.
State Project Manager
303-692-3548
Colorado Department of Public Health and Environment
4300 Cherry Creek Drive South
Denver, CO 80246-1530
Email: shaun.cwick@state.co.us
Paul Stoick, P.E.
Remedial Project Manager
303-312-6908
U.S. EPA Region 8 (EPR-SR)
1595 Wynkoop Street
Denver, CO 80202-1129
Stoick.Paul@epa.gov
Background
The five-square-mile Chemical Sales Co. Superfund Site (site) is located in Denver, Colorado.
The site was first developed in 1962 with the construction of a warehouse. Operations on site included the storage and repackaging of bulk chemicals from rail cars and drums. In 1981, a random sample of municipal drinking water identified groundwater in South Adams County Water Supply District as contaminated with volatile organic compounds (VOCs.) Groundwater studies by EPA led to the site’s discovery as the main source of VOC contamination in the area.
Following cleanup, operation and maintenance activities are ongoing.
What Has Been Done to Clean Up the Site?
The site is being addressed through federal and state actions.
The Colorado Department of Public Health and Environment, with EPA oversight, has conducted several five-year reviews at the site. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by site decision documents. The most recent review concluded that response actions at the site are in accordance with the remedy selected by EPA and that the remedy continues to be protective of human health and the environment in the short term. However, long-term protectiveness requires evaluation of 1,4-dioxane, an emerging contaminant in groundwater. EPA placed the site on the Superfund program’s National Priorities List (NPL) in August 1990.
What Is the Current Site Status?
The site consists of four areas, referred to by EPA as operable units (OUs). OU1 addresses contaminated subsurface soils on the Chemical Sales Co. property and groundwater contamination south of Sand Creek. OU2 addresses VOC-contaminated groundwater north of Sand Creek. OU3 addresses residential exposure to contaminated groundwater in OU2. OU4 addresses South Adams County Water Supply District wells 18, 21 and 47. The wells provide water to residents connected to the water district.
Completed cleanup activities included connection of over 400 residences to the South Adams County Water and Sanitation District (SACWSD) municipal water supply in 1986, 1992 and 1995, construction of the Klein Treatment Plant for SACWSD in 1989, and removal of leaking and corroded drums from the Chemical Sales Co. property in 1989.
Additional cleanup activities included treatment of contaminated soils with soil vapor extraction (SVE), treatment of contaminated groundwater through air sparging and SVE, treatment of extracted vapors with a resin adsorption unit, and groundwater extraction to prevent further migration of contamination. Institutional controls have also been implemented.
Construction of the original remedy to treat the source area was finished in December 1999. In 2007, it was determined that a different technology would more effectively treat the source area. The new technology, called In-Situ Chemical Oxidation (ISCO), involved the injection of chemicals into the subsurface to break down site contaminants into less harmful byproducts. Currently, groundwater is being monitored to evaluate the effectiveness of source area remediation.
The Agencies are currently evaluating the most effective way to continue to remediate the source area and downgradient groundwater contamination. The Agencies have released a Draft Final Focused Feasibility Study (FFS), which evaluates different approaches for cleaning up the site. The Agencies are planning to conduct a pilot study of what appears to be the most appropriate remedial technology prior to finalizing the report and making a decision regarding future remedial actions.
Draft Final FFS