A Beginners Guide To Mine Reclamation And Wetland Construction
Environmental article by Harold Hough
Mine reclamation presents many challenges, but constructing or reclaiming a wetland is one of the most challenging. Yet, its benefits as a trap for contaminants, home for wildlife, aesthetic appeal, and recreational uses make it a critical part of a reclamation program.
The problem is that wetland construction isn’t cheap. Unlike many reclamation programs which just require re-contouring the ground and revegetation, wetland development requires many sciences to balance the hydrology, soil, plants, wildlife and even the microbes in the soil. That’s why building a wetland can run from a few thousand dollars an acre to over one hundred thousand dollars per acre.
But wetlands are more than muddy spots that harbor mosquitoes. They are an important part of the ecology of an environment. They provide valuable habitats for invertebrates, fish, and wildlife. They also store surface water and provide a buffer for rainwater runoff, which cuts down on flooding. They also remove nutrients, sediments, and contaminants from water. And, even a small wetland can boost wildlife in a reclaimed area and make it an attraction for hunters, picnickers, and bird watchers.
However, there are different wetlands for different purposes. For example, to be successful for duck hunting, the site must be flooded during the duck season. To be successful as a water treatment area, wetlands need water available during the summer to allow for growth of wetland vegetation.
Which brings us to the most important ingredient for a successful wetland – water. The amount of water needed to flood the wetland will depend on the objective of the wetland, topography of site, preferred water depths and soil type. The timing of water availability is also an important consideration as we saw in the difference between hunting and water treatment wetlands.
The soil is also critical. It can’t allow the water to drain and it must be able to support the critical chemical and biological activity that takes place right under the surface and is critical to the health of a wetland. In a reclamation project, the best bet is to salvage the wetlands soil and plants before mining. It matches the characteristics of the area and will reduce the recovery time for the wetland.
The final use of the wetland will determine the desired water depth. Water treatment purposes will have different requirements than recreational purposes like hunting and bird watching. Wetlands developed for water quality improvement should be shallow enough, generally less than 12 inches, to allow growth of thick stands of wetland vegetation. However, most species of wetland wildlife prefer water depths 10 inches or less for feeding. This is particularly important for wading and shorebirds,
Water depth for wetlands becomes more complicated if one of the purposes is to attract ducks. If the primary interest is habitat for dabbling ducks such as mallards, pintail and teal, water depths should be 18 inches or less. But, diving ducks such as scaup, ring-necked ducks and buffleheads, prefer deeper water.
Construction of wetlands for bird sanctuaries is common in mine reclamation. Many people are surprised to learn that Utah’s 3,670-acre Inland Sea Shorebird Reserve (ISSR) was developed by Kennecott Copper. This reserve is one of the most significant achievements in protecting the environment in the Salt Lake Valley. And, since 75% of Utah’s wetlands are located around the Great Salt Lake, the ISSR is critical in protecting Utah’s wetlands.
What Kennecott went through shows how complicated wetland construction is. Ecologists and engineers had to “terraform” the land in order to be a wetland. The company secured alternative water sources to create and sustain the wetlands, dug ditches to bring the water to the area, and constructed shallow earthen dams to contain the water. The wetland and associated upland communities provide important feeding, staging (resting), and breeding habitats to migratory waterbirds. By early 1997, the area had been transformed into the Inland Sea Shorebird Reserve (ISSR). The Reserve now attracts migratory shorebirds and waterfowl and provides habitat for many other wildlife species. Overall, between 2 and 5 million shorebirds representing 200 different species visit the Great Salt Lake and its surrounding wetlands each year.
Several mines have discovered wetlands constructed along streams and rivers can be managed to provide spawning and fish rearing areas. Water needs to be controlled to allow fish movement, and water levels must be maintained throughout the summer months to allow time for young fish to grow. This type of wetland also needs some deeper water to moderate high water temperatures in the summer.
One example of wetland reclamation to improve fish populations can be found in Wisconsin. Badger Mining built a new corporate headquarters, on an industrial wasteland that was a former dump for local foundries. During the construction process, the company moved 150,000 yards of fill and added topsoil to half the property. The company made the area a wildlife refuge with a four-acre fish lake and a two-acre wetland. Piles of dirt that had blocked the flow of water from the lake were removed so walleye could begin breeding in the area once again.
But wetland management isn’t just for the Midwest. It also works in the arid West, although the risk of failure is higher. Nevada is home to a large game fish called the Lahontan Trout. Unfortunately, commercial fishing 100 years ago, dams, and water diversion had reduced the Lahontan’s range to three percent of its former habitat.
The Goldstrike Mine helped to reverse that trend. It donated money and provided engineering skills for making Mary’s River an interconnected habitat for the fish. Meantime, volunteer groups of miners restored the river’s banks. Some placed rocks to create pools and others planted willows, which shade and cool the water from the summer sun. The result is that there are four times as many Lahontan Trout than just a few years ago.
Although wetland construction can be complicated, mines have found that the investment in turning a few acres into wetlands pays off in the long run.