The Tailings Area, to the east of the Moira River, was once a natural lowland area. During the ore refining process, ferric hydroxide (red mud) was pumped as waste slurry from the hydrometallurgical plant that operated from 1914 to 1961. The Ministry of the Environment covered this area with a half a metre of crushed limestone in 1986/ 1987 to eliminate wind and surface water erosion and to address chemistry related issues. The cover also acts as a shield against low-level radioactivity, also present in the tailings.
Area: 13 hectares (ha)
Contaminants of Concern: Arsenic, cobalt, copper, nickel, and low-level radioactive material.
Volume of Wastes: Approximately 45,000 m3
Cover tailings with an engineered soil cover combined with collection/treatment of groundwater and upstream surface water flow diversion.
The existing limestone cap in this area will be covered with an engineered cap that is 1.75 metres thick, and vegetated with hybrid poplar trees and grass. These measures will prevent 90 percent of precipitation (surface water) from infiltrating the tailings.
Ground and surface water management
An interceptor ditch will be built to divert clean, upstream surface water away from the engineered cover.
Water collection/ treatment
Contaminated seepage will be pumped and collected for treatment at the Arsenic Treatment Plant.