Closure objectives for water management
Kaisa Turunen and Antti Pasanen. Geological Survey of Finland, P.O. Box 1237, FI-70211 Kuopio, FINLAND, e-mail: kaisa.turunen(at)gtk.fi, antti.pasanen(at)gtk.fi
Objectives of water management in closed mines
When aiming for an acceptable post-closure water management the following objectives must be met (modified after Caldwell, 2007).
- Proactive, integrated water management which takes into account the chemical, biological, ecological and quantity issues for the water is the key for a sustainable post-closure water management
- Surface water control is essential in avoiding pollution of water resources in the mining area and outside it
- Ground water flow paths and hydraulic properties must be known to prevent pollution of ground water resources
- Excess runoff needs to be diverted from mine workings and waste areas.
- Different types of water should be kept separate to minimise the need for water treatment.
- The surface waters and ground waters on-site and off-site need to be monitored and actions should be taken if the monitoring shows adverse changes.
- Limit the infiltration of water to mine waste disposal facilities
- Control the erosion of the mine site to limit the sediment runoff
- Control the erosion that may cause damage to mine closure works
- Select the water management technologies that are long lasting, erosion resistant and low maintenance
- Plan the runoff as low maintenance as possible, preferably gravity driven
In order to meet these objectives the hydrological and hydrogeological conditions of the site must be known, including the hydraulic heads and groundwater-surface water interactions, the water balances need to be managed and monitored, the water quality needs to be monitored and the water management structures need to be selected such a way that they will not deteriorate during the time or they can be easily maintained.