You are here:
Upper Tenmile Creek Mining Area
|Site Type: Final NPL
City: Near Helena
County: Lewis and Clark
Street Address: Rimini Road
ZIP Code: 59601
EPA ID: MTSFN7578012
Congressional District: At Large
Updated October 2011
The Upper Tenmile Creek Mining Area Superfund Site received $6.45 million through the American Recovery and Reinvestment Act (ARRA).
Significant progress was made on the three ARRA projects at Upper Tenmile Creek during fiscal year 2011. Working within a fairly confined space within the community of Rimini:
- The main road through Rimini was completely excavated and backfilled to remediate contaminated material. Approximately 18,000 cubic yards of waste were removed from one mile of Rimini Road. Removal of this waste reduces the potential for residents to be exposed to contamination as well as prevents future erosion and distribution of wastes via the adjacent Tenmile Creek.
- Nearly all of the residential yards were remediated, with new septic systems installed and landscaping completed; four yards remain to be remediated. Approximately 6,000 cubic yards of waste were removed from the yards in Rimini and 9,000 cubic yards from the Lee Mountain site.
- Approximately 133,000 cubic yards of material were moved for the Luttrell Repository highwall layback project. This created additional space at the repository and improved the stability of the slopes.
The Upper Tenmile Creek Mining Area site is located in the Rimini Mining District, southwest of Helena, Montana. It consists of numerous abandoned and inactive hard-rock mine sites that produced gold, lead, zinc and copper. Mining began in the district before 1870 and continued through the 1920s. Little mining has been performed there since the early 1930s.
EPA added the Upper Tenmile Creek Mining Area to the Superfund National Priorities List on October 22, 1999, due to mining waste problems in the 53-square-mile watershed. The small historic mining community of Rimini is located within the Superfund site boundaries.
The site includes the drainage basin of Tenmile Creek upstream of the Helena water treatment plant and includes tributaries that supply water to the plant's five intake pipelines. EPA identified 150 individual mine sites within the watershed boundary, of which 70 have been prioritized for cleanup. Many of these mine features are above the five City of Helena drinking water intakes, which supply about 50 percent of the city's water.
The watershed has many stakeholders, including landowners, local communities, local and state government, special interest groups and several federal agencies, including EPA. Collaboration among the stakeholders is necessary to achieve a cleanup that will be expedient, efficient and long-lasting.
|Media Affected||Contaminants||Source of Contamination|
|groundwater, stream, soils||arsenic, cadmium, copper, lead, zinc||historic mining activities|
Contaminants of concern are heavy metals, primarily arsenic, cadmium, copper, lead and zinc. Arsenic, cadmium and lead pose risk to human health while copper and zinc are toxic to fish.
EPA staff is coordinating with other state and federal agencies by addressing Clean Water Act problems related to mining wastes in the watershed that have been identified by the state. Tenmile Creek is the state's top priority for a Total Maximum Daily Load (TMDL) allocation.
EPA focused the Upper Tenmile risk assessments on development of risk-based preliminary remediation goals (PRGs) for the entire site. These are chemical-specific concentrations for various media, such as groundwater, that are protective for human health and the environment. Potential exposures to contaminants of concern in soil, groundwater, surface water, sediment, interior dust, airborne particulates and fish were evaluated. Based on land uses at the time of the risk assessment and potential future land uses as determined by observed trends and consultation with Lewis and Clark county officials, EPA considered the primary populations of concern to be residents, recreational visitors and workers.
The Upper Tenmile site is being cleaned up using a collaborative, watershed approach. To date, EPA has been unable to identify a potentially responsible party, so the cleanup on private land is being 90 percent paid for with federal funds and 10 percent with state funds. Cooperating agencies have combined resources to expedite a watershed cleanup. The U.S. Forest Service has taken the lead role in cleaning up wastes on federal property within the Superfund site boundary (Beatrice, Justice and Armstrong mines). Where individual mines involve both federal and private lands (Upper Valley Forge mine), cleanup expenses are shared by EPA and the Forest Service, with the State of Montana paying 10 percent. EPA and the Forest Service also share construction and maintenance costs of a joint mine-waste repository. Throughout the cleanup, EPA continues to work closely with the Forest Service, state and local community.
During the 2010 and 2011 construction seasons, significant progress was made at the Upper Tenmile site. The main road through the community of Rimini was excavated of contaminated material and clean fill was placed and graded to accommodate proper water runoff and access. All but four yards in Rimini were excavated of contaminated material, new septic systems were placed and the yards were seeded. The Lee Mountain Mine contaminated soil was removed. The Luttrell Repository highwall layback was completed, thereby providing additional storage capacity and addressing state slope requirements. Construction activities enhanced by the ARRA funds were Rimini yard remediation, Rimini road remediation, Lee Mountain Mine remediation and Luttrell Repository highwall layback. Work on Rimini Road was completed in 2010, while the remainder of the activities were completed during the 2011 construction season.
Landmark Subdivision also saw remediation activity in 2010. Eleven yards had 27,000 cubic yards of waste excavated followed by clean fill replacement; landscaping was finalized on the involved properties.
During construction, every effort was made to facilitate the flow of truck traffic from the remediation sites to the repository, as well as coordinating large equipment working on the various projects. U.S. Forest Service roads were closed during the week and all traffic was controlled by flag personnel.
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.
Throughout EPA's Superfund response action at the Upper Tenmile Creek Mining Area site, the agency has provided information to the public through public meetings, the administrative record file for the site, fact sheets and announcements published in local newspapers. EPA participates in monthly meetings of the Upper Tenmile Watershed Committee and routinely discusses the cleanup plans with area residents and property owners.
In addition, during the field season, EPA distributes periodic construction updates and maintains a project office in Rimini, where residents are welcome to stop by with questions. Tours and briefings are offered to local officials.
EPA also provides funding to Rimini Community, Inc., to obtain independent technical assistance though a Technical Assistance Grant (TAG). The TAG was awarded in 2005 and renewed through 2011.
EPA's Community Involvement Plan for the site is available in the Site Documents section below.
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. EPA uses 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.
Many properties in Rimini and in the Landmark Subdivision are already in continued use as residential properties.
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.
Institutional controls are being formulated to address limited circumstances of waste left in place. During the cleanup efforts at both Landmark and Rimini, landowners asked that many trees be left in place. EPA documented the request and soils were remediated up to the base of the trees so as to not impact the tree root system. This effort may have left a small amount of contaminated soils within the root system of the tree. Lewis and Clark County is working with EPA to provide a system where subsequent disturbance of residual waste can be documented and be appropriately disposed of. EPA also is working with Lewis and Clark County and the Montana Department of natural Resources and Conservation to institute a groundwater control area within the boundary of the Upper Tenmile Watershed.
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.
The first five-year review of the Upper Tenmile site was completed in 2008; the report is available in the Site Documents section below or the EPA office in Helena. The next five-year review is scheduled for 2013.
You will need Adobe Reader to view some of the files on this page. See EPA’s About PDF page to learn more.
Best way to open a very large file: right-click and save it to a folder.
Update to the Five-Year Review, January 2011
First Five-Year Review Report (PDF), July 2008 (61 pp, 2.1 MB)
ROD Amendment Fact Sheet, September 2008
Community Involvement Plan, July 2008
EPA Cleanup Update July 31, 2008
EPA Cleanup Update September 30, 2007
Proposed Plan to Amend the 2002 Record of Decision (ROD), October 2007
Upper Tenmile Creek Mining Area Fact Sheet, January 2007
Record of Decision (PDF), June 28, 2002 (361 pp, 2 MB)
Remedial Project Manager (for OU1)
U.S. Environmental Protection Agency
Region 8, Montana Office
10 West 15th Street, Suite 3200
Helena, MT 59626
866-457-2690 (toll free)
Montana Department of Environmental Quality
1100 North Last Chance Gulch
P.O. Box 200901
Helena, MT 59620-0901
800-246-8198 (toll free in-state only)
Site Information Repository:
EPA Superfund Records Center
10 West 15th Street, Suite 3200
Helena, MT 59626
866-457-2690 (toll free)
Hours: M-F, 8:00 a.m.-4:30 p.m.
The following links exit the site Exit