EPA seeks public comment on proposed update to Dover landfill Superfund site cleanup plan

posted on 4/28/2022

On April 27, 2022, the U.S. Environmental Protection Agency (EPA) proposed an update to the agency's plan to clean up the Dover Municipal Landfill Superfund Site located on Tolend Road. The proposed update is formally called an "Explanation of Significant Differences" (ESD) and ensures the cleanup will continue to be protective of human health and the environment, according to the EPA.

The EPA is accepting public comments on its proposed ESD update for two weeks, beginning April 27, and continuing through 11:59 p.m. on Wednesday, May 11, 2022.

EPA selected a comprehensive remedy through the site's Record of Decision in 1991 and subsequent decision documents to address risks to human health with two components: source control and management of migration. The source control component consists of a multi-level groundwater extraction system. The management of migration (MOM) component addresses two groundwater contaminant plumes migrating from the landfill. The MOM component pumps and treats contaminated groundwater from the southern plume while allowing the eastern plume to degrade naturally.

Proposed changes to the remedy in the ESD include:

• Addition of 1,4-dioxane as a contaminant of concern using the current state groundwater standard as the cleanup level;
• Modifying the cleanup level for tetrahydrofuran in groundwater to reflect the current state groundwater standard, following EPA's risk standards;
• Switching the terminology used for groundwater Cleanup Levels from "Interim Cleanup Levels" to "Cleanup Levels," based on the EPA's revised cleanup terminology.
• Clarifying the site-specific approach to determine when groundwater cleanup levels have been attained. This updated approach supports determinations when groundwater at the site has been restored for its permissible, beneficial use and no longer presents an unacceptable risk to human health due to site-related contaminants, according to the EPA.

The complete Explanation of Significant Differences document is available at the EPA's dedicated website for the Dover landfill, www.epa.gov/superfund/dover, which also includes other documents and information related to the site.

The New Hampshire Department of Environmental Services (NHDES) has reviewed the ESD and supports the proposed changes. EPA and the NHDES will evaluate public comments on the proposed changes before making the final decision to approve the ESD. The ESD will not fundamentally change the terms, scope, performance, or cost of the EPA's plan to clean up the Dover Municipal Landfill site established in 1991 and updated in 2004 and 2009.

Comment on the proposed update by mail or email through May 11

The public can comment on the proposed update through 11:59 p.m. Wednesday, May 11, 2022, by email or mail. Direct comments to Gerardo Millan-Ramos.

By email: Millan-Ramos.Gerardo@epa.gov.

By mail:
Gerardo Millan-Ramos
U.S. EPA Region 1 Mail Code: 07-1
5 Post Office Square, Suite 100
Boston, MA 02109-3912

Comments by mail must be postmarked by May 11, 2022, to be accepted.

For more information or questions, contact EPA Community Involvement Coordinator Charlotte Gray at gray.charlotte@epa.gov or 617-918-1243. 

Background

The City of Dover owns the 50-acre inactive landfill on Tolend Road and operated the landfill from 1960 to 1980. The landfill accepted domestic and industrial waste, including leather-tanning wastes, organic solvents, municipal trash and sludge from the Dover wastewater plant. Facility operations contaminated groundwater with volatile organic compounds and arsenic. In 1977, the state installed monitoring wells around the area and found that organic solvents were entering the groundwater, posing a potential threat to nearby residential wells and public water supplies for Dover and Portsmouth. The site was added to EPA's National Priorities List in 1983.