A.6 Callahan Mining, ME

A.6.1 Contacts

Ed Hathaway

US Environmental Protection Agency, Region 1

[email protected]

 

Naji Akladis

Maine Department of Environmental Protection

[email protected]

A.6.2 Summary

Environment:	Tidal estuary
Scale:	Full
Contaminants of Concern:	Arsenic, PCBs, cadmium, copper, lead, zinc
Source Control Achieved Prior to Remedy Selection?	No
Final Remedy:	Removal and cappingTechnology which covers contaminated sediment with material to isolate the contaminants from the surrounding environment.
MNR viewed as a success?	Remedy in proposal phase

A.6.3 Site Description

The Callahan Mine site is located approximately 1,000 ft (305 meters) east-southeast of Harborside Village in the town of Brooksville, Hancock County, Maine. Mining operations were conducted adjacent to and beneath Goose Pond. The 150-acre property is located in a coastal, rural setting on the Cape Rosier peninsula. The mine is currently underwater and subject to daily tidal exchange in Goose Pond. Goose Pond is connected to Goose Cove to the north by Goose Falls. Goose cove is on the southern part of Penobscot Bay.

Site contamination is attributed to spillage during transport, storage, and handling of ore and ore concentrate; disposal of tailings, disposal of waste rock; and contaminated wind-blown dust. PCB contamination is attributed to historical transformer leakage. The zinc/copper sulfide deposit in Goose Pond was discovered in 1880 at low tide. Efforts to mine the ore continued until 1964. Open pit mining activities began in 1968. Two dams were constructed at the saltwater and freshwater inlets. The pit was approximately 600 ft in diameter and 320 ft deep.

Approximately 5 million tons of non-ore-bearing waste rock were removed from the mine and stored in piles throughout the property. Approximately 800,000 tons of ore-bearing rock removed from the mine during open pit excavation was processed through a series of crusher mills and minerals removed using the flotation process. Sediment laden water from the crushing process was discharged directly into Goose Cove through a 16-inch pipeline. The remaining nonmineral particles and residues of the chemical reagents from the flotation process were discharged as a slurry to an 11-acre tailings pond on site. Mining and milling operations ceased in 1972.

USEPA completed a Human Health and Ecological Risk Assessment, which revealed the presence of copper, lead, and zinc in sediments of Goose Pond at levels acutely toxic to benthic organisms. Metals were found to be accumulating in biota at the site and food chain modeling identified sediments in Goose Pond and the adjacent salt marsh as a threat to insect and fish-eating birds. Surface water also contains metals at concentrations that could adversely impact aquatic organisms.

In 2010, USEPA separated the OU 1 Record of Decision activities into two components. The sediment and waste rock excavations, disposal in the CAD cell, and the system for the tailings impoundment will be addressed in OU 3.

CSM summary: There are six primary contaminant source areas at the site (the tailings pile, three waste rock piles, the ore pad, and the former operations area) and four secondary contaminant source areas (Dyer Cove, Goose Pond, the former mine pit, and Goose Cove). The release mechanisms are acid rock drainage and leachingLeaching is the extraction of certain materials from a carrier into a liquid; usually, but not always, a solvent. of metals to groundwater and surface water, erosion, windblown dust, and slope failure. Potential receptors include ecological and human. Metals have been found to be accumulating in biota and food chain modeling identified sediments in Goose Pond to be a threat to insect and fish-eating birds. The site is not enclosed and unauthorized recreational use leaves the potential for human contact with contaminated soil, sediment, and surface water.

A.6.4 Remedial Objectives

RAOs/project objectives for this site include:

• Prevent exposure of biota to sediment including the sediment/soil in the salt marsh, with concentrations of copper, lead, or zinc that may represent a threat to insectivorous and piscivorous birds, fish, and other aquatic organisms.
• Minimize impacts from waste rock and tailings within the OU 3 area on groundwater, surface water, and sediment.
• Stabilize the tailings impoundment to achieve acceptable stability criteria.
• Comply with the applicable or relevant and appropriate federal and state regulations that apply to the cleanup action.

A.6.5 Remedial Approach

The proposed remedy for this site includes the following tasks:

• Excavate waste rock/source materials and dispose of the excavated material in a CAD cell in the former mine pit.
• Dredge the Southern Goose Pond mine and adjacent salt marsh with disposal of waste in the CAD cell.
• Cap and stabilize the tailings impoundment with surface water diversion around a horizontal drain within the tailings impoundment.
• Install a wetlands treatment system to treat the discharge of contamination from the horizontal drain that will be installed within the tailings impoundment.
• Impose land use restrictions to prevent disturbance of the capA covering over material (contaminated sediment) used to isolate the contaminants from the surrounding environment., wetlands treatment system, and CAD cell.
• Restore disturbed areas, including wetlands, and the possibility remove mine waste in Goose Cove and Goose Pond as part of the wetland mitigation activities.

The remedy is likely still in the early proposal stage and was separated out from OU 1 to make up OU 3 in 2010.

A.6.6 References

USEPA Waste Site Cleanup & Reuse in New England, Callahan Mining Corp. http://yosemite.epa.gov/r1/npl_pad.nsf/701b6886f189ceae85256bd20014e93d/584c38df37ade1998525764f005a96d3!OpenDocument.

Publication Date: August 2014