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National Information |
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Superfund Program
Twins Inn
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Site Type: Non-NPL Status, Removal Only
Site City: Arvada County: Jefferson County EPA ID#: CO0001101476 Site Aliases: Thoro Congressional District(s): 7 |
Site Description
The Twins Inn Site is located in both the City of Arvada and unincorporated Jefferson County, about 10 miles northwest of downtown Denver, Colorado. The site area includes a few residences and commercial/industrial businesses which primarily use municipal water supplies. One of the businesses in the area is the Twins Inn Tavern from which the site derives its name.
In 1995, EPA discovered that the well at the Twins Inn Tavern was contaminated
with a chlorinated solvent called trichloroethene (TCE) as well as other organic
chemicals in excess of drinking water standards. In response, EPA sampled domestic
wells, monitoring wells, groundwater, surface water, and some soil in the vicinity
near the well. EPA traced the source area to the Thoro Products Co. property
at 6611 West 58th Place. Thoro Products Co. was a small family-owned business
that manufactured laundry spot removal, janitorial supplies, and cleaning products.
Thoro Products Co. also acted as a distributor of bulk chemicals for various
companies, including Dow Chemical Co. and others, and conducted solvent recycling and drum
washing operations for a few years.
Operations on this property resulted in the soil and groundwater being contaminated
with chlorinated solvents and other chemicals in the area. The groundwater contaminant
plume from this site originates near W. 58th Ave. and Nolan St. in the city
of Arvada. It extends east-southeastward almost to Sheridan Blvd. The plume
generally runs parallel to Ralston Creek.
Site Risk
Currently, there is little risk to individuals being exposed to the contaminated soils onsite because the contamination is mainly below the ground surface. Based on earlier indoor air sampling, breathing indoor air at area residences situated directly over the plume did not pose an unacceptable risk to human health. However, indoor air sampling has not yet been conducted in commercial buildings overlying the highest groundwater concentrations levels. EPA's proposed remedy anticipates future air monitoring and mitigation efforts where necessary.
Domestic use of untreated groundwater for drinking, cooking, and bathing would
pose an unacceptable risk to human health. Within the area of the plume, there
are only two residences and a local tavern that use a well as a source for drinking,
cooking and bathing. That well has been fitted with special carbon filters that
treats and removes the contamination before it is used/consumed by the residents
or the customers of the local tavern. Therefore, there is no risk to the users
of that well.
Cleanup Progress
In 1995, EPA provided bottled water and then installed a water treatment system for the affected residences and the Twins Inn Tavern. Annual water sampling is performed to see that the water treatment system is working properly.
EPA conducted field investigations, and numerous site sampling efforts to understand the extent of the groundwater contamination and the source of the contamination.
EPA's Preferred Alternative for this Site is a combination of Soil Excavation with Offsite Treatment and Disposal because it achieves the best balance of overall protection of human health and the environment; long term effectiveness; and reduction in toxicity, mobility, and volume.
The soil removed from the Site will be transported by a licensed contractor and disposed at a permitted facility.
Based on groundwater modeling results, if the soil source is removed, the groundwater plume is expected to meet cleanup goals within about 20 years regardless of the treatment method.
The Preferred Alternative for groundwater is Monitored Natural Attenuation.
Monitored natural attenuation can be used if the soil source is removed so that
there is no longer a continuing source of contamination to groundwater. MNA
will allow for natural processes to cleanse the remaining groundwater contamination
over time. Monitored Natural Attenuation is simple to implement, is cost-effective,
and would achieve remedial objectives.
Site Documents
Twins Inn Fact Sheet (PDF, 10 pages, 246 kB)Feasibility Study Text (PDF, 122 pages, 578 kB)
Feasibility Study Tables 2-2 Through 10-1 (PDF, 46 pages, 463 kB)
Community Involvement
Community involvement efforts at this site include using fact sheets, public notices and public meetings. Fact Sheets are used to explain documents like proposed cleanup alternatives. Public notices inform the public where records are kept in the different communities.EPA and CDPHE held a public meeting on May 21, 2007 to discuss cleanup alternatives. The Comment Period for the Proposed Cleanup Plan has been extended until July 5th, 2007.
Contacts
EPA
Erna Waterman
Remedial Project Manager
U.S. EPA Region 8 (EPR-SR)
1595 Wynkoop Street
Denver, CO 80202-1129
303-312-6762 OR
1-800-227-8917 x6762 (Reg. 8 only)
email: waterman.erna@epa.gov
Patricia Courtney
Community Involvement Coordinator
U.S. EPA Region 8 (EPR-SR)
1595 Wynkoop Street
Denver, CO 80202-1129
303-312-6631
800-227-7917 x6631 (Reg. 8 only)
email: courtney.patricia@epa.gov
