The third operable unit is an additional source control remedy involving the cleanup of mercury-contaminated sediments in a wetland and certain drainageways between the area of former Nyanza, Inc. operations and the Sudbury River. These areas are referred to as the Continuing Source Areas. In summary, the remedy provides for: (1) excavation of sediment with mercury levels above 1 mg/kg from the Continuing Source Areas; (2) dewatering of the contaminated sediment; (3) disposal of dewatered sediments under a portion of the cap constructed under the first operable unit remedy; (4) reconstruction of the area of cap removed during disposal; (5) treatment, if necessary, of water from the dewatering operation with discharge to an on-Site surface water body; (6) restoration of impacted wetland areas; (7) institutional controls to limit exposure to contaminants in the Sudbury River; (8) planning and implementaion of public awareness activities to increase public knowledge about contamination remaining in the Sudbury River sediments and fish; (9) performing certain pre-design studies to aid in the design of the selected remedy; and (10) creation of a fourth operable unit to conduct additional investigation of the Sudbury River.

"Operable Unit III." "3-30-93." "PB94-963706." "EPA/ROD-R01-93-082."

ROD for OU3 of a former dye manufacturing facility. Addresses mercury-contaminated sediments in a wetland and drainageways. Remedy: Excavation, dewatering, disposal of dewatered sediments, reconstruction of area where cap was removed, treatment.