Region 8
Serving Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming and 27 Tribal Nations
Superfund Program
National Information
Regional Information
Site Information
National Priorities List (NPL) History
Proposed Date
12/30/1982
Final Date
9/08/1983
Construction Completion Date
9/30/1992
Deletion Date
7/05/1996
Arsenic Trioxide
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Site Type: Deleted NPL City: Lidgerwood, Wyndmere, Richland County: Richland, Ransom, Sargent Street Address: SE North Dakota Zip Code: 58053 EPA ID#: NDD980716963 Site ID#: 0800522 Site Aliases: None Congressional District(s): At Large |
The Arsenic Trioxide site has received $10 to $25 million in new funding through the American Recovery and Reinvestment Act of 2009. The additional funds will be used to provide 180 households in the Richland, Ransom and Sargent counties with safe drinking water. EPA and the State of North Dakota will connect rural water users to a public water supply because many drinking water wells in the area are contaminated with elevated levels of arsenic. The funding will also pay for the expansion of water treatment and distribution facilities. When these homes are connected to the water system, the cleanup work at the Arsenic Trioxide site will be complete.
Site Status & Updates
During the summer of 2008, approximately 60 additional rural users were connected to a public water supply because of elevated arsenic concentrations in their drinking water wells (Segment 3). The design for Segment 4 has been finalized and bids for the work are currently being solicited. Segment 4 will involve connecting approximately 150 rural users to a public water supply during the summer of 2009. Work on the design for Segment 5 is anticipated to begin in summer 2009.
In September 2008 the bottled water program transitioned from EPA's Removal Program to the State of North Dakota Department of Health (NDDH). The bottled water program is an interim remedial action and provides clean drinking water to rural users waiting for connections to the public water supply. EPA also completed the third Five-Year Review in September 2008. This review indicated that human health will be protected in the long-term upon completion of the planned remedial actions and the implementation of institutional controls.
EPA is working with the NDDH to ensure that the residents within the Arsenic Trioxide site (the Site) boundary have safe drinking water. EPA and NDDH recently signed an additional decision document that describes: 1) the rationale for connecting approximately 30 additional rural users to the rural water service, 2) the expansion of the rural water treatment plant and storage capacities, and 3) institutional controls necessary to protect future rural users from unknowingly drinking arsenic-contaminated water. This decision document (Explanation of Significant Differences or ESD) was developed in cooperation with the North Dakota Department of Health. It is anticipated that the decision document was signed on February 20, 2009.
Site Description
The Site is located in southeastern North Dakota. It covers approximately 26 townships (about 568 square miles) encompassing portions of Ransom and Sargent counties. The Site area is sparsely populated farmland with a few small towns, including Lidgerwood, Wyndmere, Milnor and Hankinson. The Site topography is primarily low rolling hills and flat plains. Ground water aquifer systems include shallow glacial drift aquifers approximately three to 150 feet deep and the Dakota Sandstone aquifer approximately 200 to 1,000 feet deep. Ground water with elevated arsenic levels appears to be limited to the shallow, unconfined glacial drift aquifers and does not extend into the deeper sandstone unit. The upper aquifer is commonly used as a drinking water source in the region.
EPA conducted a Remedial Investigation (RI) in 1985 to determine the nature and extent of arsenic contamination in the ground water in southeastern North Dakota. The occurrence of arsenic in ground water is attributed to both the historical use of arsenic-based grasshopper bait and naturally occurring sources. The RI identified several ground water wells that exceeded the Safe Drinking Water Act (SDWA) Maximum Contaminant Level (MCL) for arsenic, which, at the time, was 0.05 milligrams per liter (mg/L).
Once the RI was completed, EPA conducted a Feasibility Study (FS) to evaluate options, or remedies, to protect human health and the environment in the areas identified in the RI where the arsenic contamination was not only naturally occurring but could be attributed, at least in part, to the bait application or storage.
The remedy for the Site provided for the expansion of three water treatment plants, approximately 300 miles of water distribution pipeline, additional water storage reservoirs and tanks, and additional water supply wells. The remedy was completed in June 1993, and the Site was removed from the National Priorities List (NPL) in July 1996. Remedial actions were taken at the site to address arsenic concentrations in ground water, which serves as the primary drinking water source in the region. At the time of the remedy, the Safe Drinking Water Act Maximum Contaminant Level (MCL) for arsenic was 0.05 mg/L, which was exceeded in the drinking water at the Site.
In 2001, the MCL for arsenic was lowered from 0.05 mg/L to 0.01 mg/L, with this new standard becoming enforceable in January 2006. This prompted a Five-Year Review in June 2003. The review determined that the remedy was no longer protective of human health. As a result of this review, the communities of Wyndmere and Hankinson were connected to the public water supply system. Construction activities also included the expansion of the Southeast Water Users District water treatment plant. Construction activities were conducted between 2005 and 2007. In addition to these activities, sampling was conducted to determine if the wells of rural water users exceeded the new arsenic standard. If well water exceeded the arsenic standard, users were provided bottled water as a temporary measure.
Site Risk
The area's residents are subject to increased health risk due to exposure to arsenic above the Maximum Contaminant Level (MCL) in untreated drinking water supplies.
| Media Affected | Contaminant | Source of Contamination |
| Drinking water | Arsenic | Historical use of arsenic-based grasshopper bait and naturally occurring (background) levels of arsenic. |
The Safe Drinking Water Act Maximum Contaminant Level for arsenic has been reduced to 0.01 mg/L. This change became enforceable in January 2006.
Cleanup Progress
The remedy to supply drinking water to meet the arsenic MCL of 0.05 mg/L was completed in June 1993. The site was removed from the NPL in July 1996. The second Five-Year Review was conducted early because of a change in the arsenic MCL, lowering it to 0.01 mg/L enforceable in January 2006. The Five-Year Review - Document Body (800 KB, PDF file) and Five-Year Review Attachments (2 MB, PDF file, LARGE!) are available online. The change in the arsenic MCL caused EPA and the NDDH to determine that the remedy was no longer protective. EPA is working with the NDDH to provide safe drinking water to area residents whose well water exceeds the arsenic MCL.
Construction activities at the site are expected to be completed in 2012.
The next Five-Year Review will be completed by September 2013. More about EPA's regulation of arsenic in drinking water from EPA HQ.
Community Involvement
Community meetings were held in August 2008 to provide a Site status update to residents. An informational fact sheet is planned for late winter 2009 to describe future actions.
Site Documents
2008 Five-Year Review (PDF, 8.5 MB)
2008 Five-Year Review attachments (PDF, 11 MB)
Federal Register Deletion July 5, 1996 (PDF, 2 pp, 193K)
Records of Decision (RODs) List
Contacts
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EPA Frances Costanzi |
North Dakota Carl Anderson, Supervisor |
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View Documents at:
Lidgerwood Public Library Southeast Water Users District
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