Phases of Site Cleanup
Portions excerpted from HoltraChem Manufacturing Site Facts, U.S. EPA, March, 2001
While ownership has changed several times, Mallinckrodt, Hanlin and HoltraChem have each worked to advance the cleanup. Several of the actions which HoltraChem and Mallinckrodt have taken to control and clean up pollution at the plant are listed below:
- Relined a lagoon to stop waste from discharging to groundwater which flows into the Penobscot River;
- Installed riprap on the riverbank next to one of the plant landfills to prevent erosion and river contamination;
- Installed a groundwater collection system to capture a portion of contaminated groundwater discharging from the site for treatment, and
- Instituted measures to prevent contaminated sediment from reaching the river.
What's Next
EPA, DEP and the company are currently discussing cleanup goals for four key areas - these standards will be the subject of a public comment period before they can be finalized in a final site cleanup plan. Current thinking, cleanup numbers and goals are listed below.
- River sediments: The most highly contaminated area - just under an acre - near the plant's outfall pipe is under consideration to be dredged. Several acres of more moderate contamination in an adjacent cove is also being considered for dredging. In all areas of the river below the southern cove there are significantly lower concentrations of mercury.
Onsite sediments: The sediment that is most contaminated will be excavated and/or buried. Excavated soils would be either disposed of offsite or consolidated onsite under a cap - designed to prevent infiltration and the discharge of contaminants.
Groundwater: A more comprehensive groundwater collection, treatment and discharge control program is also being discussed.
Surface water: Cleanup standards will be set for both the surface water drainage on site and the Penobscot River. The cleanup measure to achieve these goals will include cleanup of soil and groundwater and the prevention of soil movement.
Soil: Variable amounts of contaminated soil exist in the main plant area and landfill areas. Options being discussed include removal and disposal of soil offsite or consolidation of soil onsite under a cap designed to prevent infiltration and the discharge of contaminants.
