Keddy Mill

Overview

Keddy Mill is a 6.93-acre abandoned mill complex in Windham, Maine, with industrial roots going back to the 1750s. The site operated as a pulp mill starting in 1875 and later made steel products through the 1970s. During that period, hazardous substances including polychlorinated biphenyls (PCBs) were disposed of at the property. The EPA added the site to the National Priorities List (Superfund list) in May 2014.

The site has 25 confirmed contaminants of concern spread across groundwater, soil, sediment, and fish tissue. Soil and debris contain PCBs at concentrations as high as 24,000 parts per million, along with asbestos, dioxins, heavy metals, and other compounds. Groundwater shows elevated levels of vinyl chloride, trichloroethene, arsenic, and other organic and inorganic chemicals. PCBs have also reached sediment and fish tissue in the Presumpscot River between Little Falls and Mallison Falls. EPA advises against eating fish from that river segment until cleanup is complete.

The EPA signed a Record of Decision in September 2023 selecting the cleanup approach. It calls for excavating roughly 22,000 cubic yards of contaminated soil and debris and about 320 cubic yards of river sediment, treating groundwater in place using activated carbon and bioremediation, and restoring wetland habitat. The estimated construction cost is about 17 million dollars. ITT LLC is the responsible party and has reached an agreement with EPA to carry out the work. Institutional controls, including an Environmental Covenant signed in December 2025 for the 7 Depot Street parcel, already restrict groundwater use, well installation, and subsurface activity on the property.

Cleanup is organized into two tracks. A Non-Time-Critical Removal Action will demolish the deteriorating mill building, which poses risks to trespassers and spreads contaminants through a caving roof. Demolition design is expected to finish in 2026, with the removal action estimated to begin between late 2026 and early 2027 and finish by late 2028. The broader remedial design for soil, sediment, and groundwater work is estimated to begin between September and November 2027. The site has not yet been deleted from the National Priorities List, and human exposure status has not been fully determined because response activities are still in early stages. Groundwater migration is currently under control.

Community members can review site documents at the Windham Public Library or at the EPA Region 1 records center in Boston. For questions, community members can contact the EPA's Community Involvement Coordinator.