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

Introduction

Definition of mine water is “all water emanating from active, abandoned or closed surface or underground mines” (ERMITE Consortium et al. 2004), including draining from the dewatering adits, mine dewatering pumps, open pit mines and raw material handling facilities on the mine site (ERMITE Consortium et al. 2004). Therefore, all the waters entering, exiting and circulating at the closed mine site needs to be managed to reach an acceptable water management status. To reduce costly water treatment and possible problems caused by e.g. heavy rains or other high discharge events at a closed mine site, it is also important to keep the unaffected surface runoff and groundwater away from the contact of the possibly polluted waters and divert it past the mining operations.

Mining usually affects the water quality by exposing more reactive surface in quarry, tailings and waste rock piles, but it also alters the hydrological and topographical characteristics of the mine site which affect in surface water and ground water quantities and runoff, soil moisture and evapotranspiration. The degraded water quality and changed runoff conditions may pose a significant risk to water resources and aquatic environments. Mine waters can also be in good chemical and biological condition but the polluted mine water produces one of the largest waste water streams in Europe (Wolkersdorfer 2005). It is essential to set up an environmentally sound post-closure mine water management plan to prevent pollution and significant impacts to humans and the environment.

The integrated mine water management is a part of the integrated water resource management at the mine site which takes into account water quality, water quantity, quality of the aquatic ecosystem and all other aspects of the water resource (Department of Water Affairs and Forestry 2008). It is based on innovative solutions in mine water management, hydrologic environmental database, continuous data collection and a design of a sustainable drainage system. The main goal is to minimize adverse environmental effects by using a pro-active approach rather than a reactive approach, by addressing the problems early which is much more ecological and economical than treating the symptoms. At a closed mining site the solutions used during the operation phase are many times modified to try to meet the demands of the water management of a closed site. Using a pro-active approach during the operation phase and planning the water management to meet also the post closure standards, such as gravity driven runoff, erosion resistant water management structures, water treatment and regulatory compliance, provides an ecologically, economically and socially durable solution. Using this approach, often small changes in planning phase are required to meet post-closure water management requirements but they can provide huge improvements. Pro-active approach also helps to avoid expensive solutions and in conjunction with integrated mine water management maximizes the productive capability of reclaimed mine landscape. The planning of the post-closure mine water management requires a participation of multi-disciplinary professionals and authorities. In post-closure water management research the hydrogeochemical behaviour and hydrodynamic development are the most essential aspects along with thorough hydrological and hydrogeological understanding.

To ensure that mine water meets environmental standards prior to being discharged, it is necessary also to monitor the surrounding surface and groundwater quality and if necessary, use a suitable water treatment technique to treat the mine water. The monitoring and sampling are presented in the Monitoring section and water treatment technologies are presented in the Water treatment section of the Closedure pages.

The water management section of the Closedure website:

tells about the objectives of water management in closed mines,
evaluates specific water management technologies,
describes selected research methods related to water management during mine closure, and
presents case examples from actual mine sites, and
the results of the R&D studies performed during the project.