Region 8

Chemical Sales Co.

Chemical Sales Co. site location map Site Type: Final NPL
City: Denver
County: Adams, Denver
Street Address: 4661 Monaco St.
Zip Code: 80216
EPA ID: COD007431620
SSID: 0887
Site Aliases: Dahlia NPL Staging
Congressional Districts: 1, 7

What's New?

Updated May 2012

Recent studies have shown that volatile organic compounds (VOCs) in monitoring wells near a building just west of the site are not decreasing as quickly as other areas of contamination. Multiple injections of a substance called "Fenton's reagent" are being injected into the subsurface to help to degrade the VOCs. To reduce cleanup costs, the Colorado Department of Health and Public Environment (CDPHE) has taken over the everyday operations of the site.

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Site Description

The Chemical Sales Co. site covers about five square miles in the northeast Denver metropolitan area, mostly in Adams County with a small portion in Denver County. Chemical Sales Co. was a wholesale distributor of commercial/industrial chemicals, detergents and water leisure products. The site was first developed in 1962 with the construction of a warehouse. Operations onsite 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 (SACWSD) as contaminated with volatile organic compounds (VOCs). Groundwater studies by EPA led to the discovery of the Chemical Sales Co. site as the main source of VOC contamination in the area. The identified plume of groundwater contamination extends from north of Sand Creek to Quebec Street on the east, Holly Street on the west, and East 86th Avenue on the north.

Map of the Superfund site boundary, February 2007

EPA proposed Chemical Sales Co. site for its National Priorities List (NPL) in June 1988 and finalized the listing in August 1990. The NPL is a list of the most serious sites identified for long-term cleanup. Under an agreement with EPA, CDPHE serves as the lead agency for this site while EPA serves as the support agency.

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Site Risk

Volatile organic compounds (VOCs) are the contaminants of concern at the site. The 1990 Risk Assessment showed that use of the contaminated groundwater for drinking, cooking or bathing could increase the chance of developing cancer. Breathing indoor air poses a potential risk if residents use the contaminated water for showering, bathing or cooking.

Media Affected Contaminants Source of Contamination
groundwater, air, soil, liquid waste, solid waste tetrachloroethylene (PCE); trichloroethylene (TCE); 1,1-dichloroethane (1,1-DCA);1,1-dichloroethene (1,1-DCE); and vinyl chloride distributor of commercial/industrial chemicals, detergents and water leisure products

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Cleanup Progress

The Chemical Sales Co. site is divided into four operable units (OUs). OUs are used at large Superfund sites to separate cleanup activities into logical components. Each OU represents a discrete action that is an incremental step toward addressing site problems. The four operable units at this site are:

OU1 consists of contaminated subsurface soils on the Colorado Sales Company property and groundwater contamination south of Sand Creek. The land use in OU1 is mainly industrial.

OU2 addresses the VOC-contaminated groundwater north of Sand Creek. OU2 is approximately four square miles in area. The land use consists of single- and multi-family residences, small businesses and municipal facilities. No soil contamination has been found in this OU.

OU3 addresses residential exposure to contaminated groundwater in OU2 and has the same boundaries as 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.

These cleanup activities have been completed:

  • Connection of over 400 residences to the South Adams County Water and Sanitation District (SACWSD) municipal supply in 1986, 1992 and 1995.
  • Construction of the Klein Treatment Plant for SACWSD in 1989. The water treatment plant treats all district water.
  • EPA removed leaking and corroded drums from the Chemical Sales Co. property in 1989.

Additional remedies selected for further cleanup were: treat contaminated soils through soil vapor extraction; treat contaminated groundwater through air sparging and soil vapor extraction; treat the extracted vapors with a resin adsorption unit; and use groundwater extraction wells to prevent further migration of contamination. Remedial design of the source area remedy was completed in May 1998. Construction of the soil vapor extraction system and air sparging system was completed December 1999. The facility is up and running and is currently meeting all the air and water permit requirements. The soil vapor extraction system has treated over 2.5 million cubic feet of soil vapor. The monitoring wells have been showing a downward trend of VOC concentrations since the system has been running.

Current operations and maintenance activities include operating the system and monitoring groundwater throughout the site.

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Community Involvement

Community involvement plays an important role in the Superfund process. EPA uses a number of different tools and resources to promote effective, on-going, meaningful community involvement. The goals of the Superfund community involvement program are to:

  • Keep communities affected by sites informed throughout the cleanup process.
  • Provide opportunities for communities to comment and offer their input about site cleanup plans.
  • Facilitate the resolution of community issues tied to a site.

Community involvement activities were conducted throughout the remedial process and comment was solicited for the five-year review completed in August 2007.

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EPA places a high priority on land reuse as part of its Superfund response program mission. The Agency tries to select cleanup options that encourage and support future use of a site. We use two fundamental methods to facilitate reuse of Superfund sites:

  • Exploring future uses before the cleanup remedy is implemented, an approach that gives the Agency the best chance of designing cleanup remedies to support the likely future use of a site.
  • Working with landowners and communities to remove barriers not considered necessary for the protection of human health or the environment at those sites where remedies are already in place.

One option for reuse is the siting of clean and renewable energy projects on contaminated (or formerly contaminated) lands. As part of this effort, EPA is evaluating the potential for energy projects on these properties and working with landowners and communities to identify ways to remove barriers to such projects.

Since the Superfund site boundaries included five square miles, many properties within the Chemical Sales Co. site were already in use before and during the Superfund cleanup and remain in use now. No additional reuse efforts are envisioned.

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Land Use Controls and Other Institutional Controls

Land use controls are the most common type of institutional control (IC). ICs are administrative or legal controls that help reduce the likelihood for human exposure to contamination. ICs can also help protect the integrity of the remedy. Examples of ICs are:

  • Zoning ordinances.
  • Environmental covenants.
  • Deed notices.
  • Well-drilling restrictions.
  • Building permits.
  • Informational advisories.

Access controls are in place at the site including a fence and a warning sign. An environmental covenant was placed on the Chemical Sales Co. property in March 2007. The covenant states that groundwater cannot be used and any new buildings will require vapor intrusion mitigation systems.

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Five-Year Reviews

EPA or the lead agency conducts five-year reviews following the start of a Superfund cleanup when contamination is left on the site. These reviews are repeated every five years. We use these reviews to determine:

  • How the remedy is working.
  • If the remedy remains protective of human health and the environment.

CDPHE, as lead agency for this site, conducted the third five-year review of the remedial actions implemented at the Chemical Sales Co. Superfund Site. The review was conducted from January through June 2007. The results of the five-year review indicate that the remedy at the site is expected to be protective of human health and the environment, and exposure pathways that could result in unacceptable risks are being controlled. The next five-year review will be completed in 2012.

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Site Documents

You will need Adobe Reader to view some of the files on this page. See EPA’s About PDF page to learn moreUpdate to the Five-Year Review, July 2011

Third Five-Year Review Report (PDF), August 2007 (65 pp, 3.6 MB)

Explanation of Significant Differences (OU1) (PDF), March 27, 2000 (17 pp, 253 K)

Record of Decision Amendment (OU4) (PDF), September 23, 1999 (31 pg, 190 K)

Explanation of Significant Differences (OU2) (PDF), November 29, 1994 (5 pp, 15 K)

Record of Decision (OU4) (PDF), December 29, 1992 (23 pp, 49 K)

Record of Decision (OU1) (PDF), June 27, 1991 (28 pp, 66 K)

Record of Decision (OU2) (PDF), June 27, 1991 (29 pp, 74 K)

Record of Decision (OU3) (PDF), June 27, 1991 (30 pp, 75 K)

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Armando Saenz
Superfund Project Manager
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street (8EPR-SR)
Denver, CO 80202-1129
800-227-8917 ext. 312-6559 (toll free Region 8 only)

Site Information Repositories:

Colorado Department of Public Health and Environment
HMWMD Records Center
4300 Cherry Creek Drive South
Denver, Colorado 80246-1530
888-569-1831 ext. 3331 (toll free)
303-759-5355 FAX
By appointment only

EPA Superfund Records Center
1595 Wynkoop Street
Denver, CO 80202-1129
To request copies of administrative record documents call:
800-227-8917 ext. 312-7273 (toll free Region 8 only)


Fonda Apostolopoulos
State Project Manager
Colorado Department of Public Health and Environment
4300 Cherry Creek Drive South
Denver, CO 80246-1530
888-569-1831 ext. 3411 (toll-free)

Jeannine Natterman
State Community Involvement Coordinator
Colorado Department of Public Health and Environment
Hazardous Materials and Waste Management Division
4300 Cherry Creek Drive South
Denver, CO 80246-1530
888-569-1831 ext. 3303 (toll-free)

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Photo/Video Gallery

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Chemical Sales Co. site at Colorado Department of Public Health and Environment Exit

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