This site was the location of a defunct manufactured gas plant (MGP) which was heavily impacted by an oily waste (coal tar). Coal tar is a brown or black liquid, which smells of naphthalene and aromatic hydrocarbons and is among the by-products when coal is carbonized to make coke or gasified to make coal gas.
Preliminary assessment/site investigation (PA/SI) activities were conducted between 2010 and 2012 which indicated that approximately two-thirds of the site was impacted by coal tar. The waste was perched on bedrock, was leaching into the adjacent Sugar River, and was detected in numerous surface soil samples above state standards. Constituents of the waste include semi-volatile organic compounds (carcinogenic and non-carcinogenic polynuclear aromatic hydrocarbons [PAHs]) and to a lesser degree, volatile organics and inorganics.
According to the U.S. EPA area planning mapping tool, there are approximately 1,200 people within ¼ mile of the site, and greater than 4,000 people within ½ mile of the site, as well as four day care centers and one nursing home.
Despite a long history of bankruptcies, acquisitions, and mergers, AmeriGas Propane, L.P. (AmeriGas) is the respondent for the site. Numerous discussions between EPA, AmeriGas, the City of Claremont, and the New Hampshire Department of Environmental Services (NHDES) have led to a cost sharing approach via an Administrative Order on Consent (AOC)/Settlement Agreement. The EPA, NHDES, and GEI, a consultant for AmeriGas, have overseen the contractor conducting the work.
Removal activities included demolition of the above ground structures, in-situ stabilization (ISS) of some deeper contaminated soil/sediment, removal of coal-tar saturated soil down to bedrock, removal of contaminated near-shore sediments along the Sugar River, temporary rerouting of a subsurface sewer pipe and replacement of a section of that pipe, and backfilling/landscaping of the property.
As site restoration activities were being finalized in the spring of 2016, standing water was observed near the sanitary sewer line and a portion of the ISS mass adjacent to the Sugar River. Before it could be sampled, the water dissipated as dryer conditions prevailed. During the spring melt in 2017, the standing water returned and samples were collected. Lab results showed that it contained no MGP related compounds or e-coli bacteria. Therefore, after discussions with the respondent and their consultant, a French drain was constructed to help drain the additional seasonal flow. Although the drain appeared to be working, standing water was once again observed in the spring of 2018. The respondent is looking into modifying the existing French drain to increase the drainage capacity.
Work began in the spring of 2017 to memorialize the history of the site and its importance to the growth of Claremont. As EPA is mandated to comply with the Historic Preservation Act, a permanent structure and informational plaques were erected after plans were shared with and comments were solicited from the City of Claremont, the NHDES, and the State Historic Preservation Office. The monument and signage were in place by the winter of 2017 and the final touchup work was completed in the spring of 2018.
The removal action was considered complete on July 5, 2018 when EPA accepted GEI’s Completion of Work Report, produced on behalf of AmeriGas. However, continuing required obligations, in accordance with the Settlement Agreement, include payment of future response costs, completion of the 1st 5-year cycle of monitoring under the ground water permit, the recording of Activity Use Restrictions, and restoration of areas impacted by the removal action to appropriate pre-removal conditions or to reasonable and suitable conditions consistent with future site use that are acceptable to EPA.
