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Mississippi and Logan TCE Plume
|Site Type: Non-NPL
Street Address: Logan Street
ZIP Code: 80210
EPA ID: CON000802437
Site Aliases: Gates, Logan TCE
Site Status & Updates
Tests of indoor air and soil vapors beneath homes in the West Washington Park neighborhood of Denver indicate contaminated groundwater in the area does not pose a health risk to residents. This conclusion is based on the sampling results of 53 homes conducted by the EPA and EnviroGroup acting on behalf of Gates Corporation and Cherokee Denver, LLC. The neighborhood tested is approximately bounded by E. Center Avenue on the north, S. Pennsylvania Street on the east, E. Tennessee Avenue on the south, and S. Broadway on the west.
The Mississippi and Logan TCE plume site is located near the former Gates Rubber facility. The site is in a mixed industrial/commercial/residential area. The site was discovered during a Colorado Department of Transportation (CDOT) de-watering operation, which was part of the transportation expansion (T-REX) and Valley Highway improvement projects. The site is adjacent to southbound I-25 near the southwest end of the Logan Street bridge.
Gates has existed there since 1911, just north of Mississippi Avenue and west of Logan Street. Industrial activities at the Gates facility resulted in soil and groundwater contamination beneath the site. The primary contaminant found was trichloroethylene (TCE), a solvent used primarily as a degreaser. Groundwater contaminated with TCE migrated north and east into the West Washington Park neighborhood. Homes in this area are connected to the municipal water supply, so drinking water is safe. Groundwater is not used for drinking water.
In December 2001, Cherokee Investment Partners purchased 50 acres of the Gates property. In October 2002, CDOT workers on the Cherokee property discovered TCE in high concentrations. Within a week of this discovery, Cherokee began drilling monitoring wells to determine the extent of the TCE and also began source area remedial actions.
Gates has retained ownership of the property immediately adjacent to and north of Mississippi Street including a building where storage tanks were located, one of which contained TCE. This area has been shown to have high levels of TCE in the soil and groundwater. TCE source areas and contaminated groundwater are being cleaned up by Gates and Cherokee under the Colorado Department of Public Health and Environment (CDPHE) Voluntary Cleanup and Redevelopment Program.
|Media Affected||Contaminants||Source of Contamination|
The contaminant of most interest is TCE, used primarily as a solvent to remove grease from metal parts. TCE in groundwater can move through soil and enter buildings as a vapor, usually through cracks or openings in the foundation slab or a crawl space. Groundwater in the area is not used as drinking water. The primary pathway for potential human exposure to TCE is through possible vapors migrating from groundwater, moving through soil and entering homes to impact indoor air quality.
Cherokee sampled indoor air in eight homes along the 800 block of South Lincoln Street and found TCE concentration levels to be far below CDPHE health-based guidelines and below national average background air concentrations.
EPA groundwater investigations have shown higher levels of TCE present in the deeper groundwater wells, which are approximately 45 to 50 feet below ground surface. The majority of shallows installed by EPA have shown no contamination. A series of more shallow wells near Kentucky Street and west of Logan Street have shown TCE at levels of concern.
Since 2004 Cherokee and EPA have drilled numerous groundwater monitoring wells in off-site residential areas to define the extent of the groundwater contamination. In 2004 Cherokee twice (in March and October) tested eight homes located over the highest TCE groundwater contamination and found indoor air TCE levels below CDPHE's health-based guideline.
To confirm those results, at CDPHE's request, Gates and Cherokee agreed to expand the indoor air sampling to include a larger area to confirm that indoor air levels were safe. This expanded study was conducted in late 2005 and early 2006 and included 29 additional homes. The results confirmed that TCE concentrations in indoor air were below CDPHE's guideline of 1.6 micrograms per cubic meter.
In 2005 EPA conducted a concurrent investigation in an adjoining area. Soil vapors were sampled beneath 16 homes (via sub-slab testing) and follow-up indoor air samples were collected in four of these homes. The results in these tests indicated that TCE indoor air levels in the neighborhood were safe.
Community meetings, fact sheet distribution and a website have been used to maintain open communications with the community. The Decker branch library maintains an site information repository.
You will need Adobe Acrobat Reader to view some of the files on this page. See EPA's PDF page to learn more.
- Trichloroethene Sampling Results for Shallow Wells, July 2005
- Trichloroethene Sampling Results for Deep Wells, July 2005
- TCE Air Values, December 12, 2005
- Deep Groundwater First Quarter 2005
- Shallow Groundwater First Quarter 2005
- Deep Groundwater Second Quarter 2005
- Shallow Groundwater Second Quarter 2005
- Deep Groundwater Third Quarter 2005
- Shallow Groundwater Third Quarter 2005
- Vol 1, Issue 1: Groundwater Testing and Initial Results, January 2005
- Vol 1, Issue 2: Groundwater: Second Round of Sampling Results, March 2005
- Vol 1, Issue 3: Groundwater: Sampling Results, March 2005
- Vol 1, Issue 4: Vapor Intrusion, July 2005
View a map of well locations and TCE results, June 2005
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street (EPR-SA)
Denver, Colorado 80202-1129
800-227-8917 ext. 312-6723 (toll free Region 8 only)
Community Involvement Coordinator
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street (OC)
Denver, CO 80202-1129
800-227-8917 ext. 312-6622 (toll free Region 8 only)