Mining is and has been a major industry in Alaska. Minerals continue to be the 2nd largest export of the Alaskan economy (1). While there are several different resources taken from Alaskan soil, this post focuses on gold. In 2013, roughly 300 placer mines exported 100,000 ounces of gold (1). Placer mines work similar to gold panning except on a larger scale. The miners dig to where an ancient streambed is buried, excavate the rock and sort it by size, and then extract the gold. You can see the old tailings, or mounds of churned gravel, resulting from this practice along creeks in interior Alaska.
Taken on the rocky stream bank at an old gold mine site in the White Mountains. Because of the difficulty in reaching sites and the time required to complete an AIM assessment, we would sometimes camp out at our sites, like this one, to reduce travel time.
If a placer mine is to operate on BLM owned land, there are some restrictions. First, only so many acres can be open to mining at any given time. Second, after mining activity is done, the miner is responsible for restoration of the disturbed area. Third, restored areas have to be approved by the BLM as restored before those acres are released from bondage, AKA the quota for open and disturbed acres. This last point means that the BLM has to approve the restoration before the miner can open new areas for exploration and extraction.
However, until this year, there wasn’t a set standard protocol for measuring whether a site was restored or not, nor an exact definition of what it meant for an area to be restored. This year, based on talks with various groups including mining communities and BLM scientists, the BLM is testing the AIM protocol as a method for measuring these sites and adapting the protocol from its use as a range tool in the lower 48 to better fit the conditions of Alaskan mines.
To be approved as restored, an area must have: 1. 70% vegetative cover 2. Meet certain species diversity requirements for different functional groups (woody, grass, forb, etc.). The presence of invasive species counts against vegetative cover. This is to incentivize miners to use native vegetation rather than non-native or invasive mixes in their restoration efforts. These goals are evaluated through the use of transects, point intercepts, quadrats, and species inventory.
The view of our first mine site that we evaluated using AIM this season. The settling pond is on the left.
What’s great about AIM is that it gives managers and miners a quantitative method for determining whether or not a site can be released. It also fosters interagency cooperation as not only do BLM field scientists participate, but also NRCS soil scientists join in to characterize soils in both disturbed and reference sites. The downside is that these mines are fairly remote. Many are off road, requiring ATVs to reach the site. Some require helicopters to drop off people and supplies as it’s impossible to reach even on ATVs. Because of these transportation difficulties, it’s expensive in both time and resources to visit these mines. AIM itself is also labor and time intensive, which adds to the cost of visiting the mines.
My fellow CLM intern and I went on a couple of AIM trips to evaluate these mines. While the mines can be hard to reach, the quantitative basis of the AIM protocol results in data that can be used to track regional health and succession over time. While there are some sites that don’t appear to be recovering, some sites are. The main difference seems to be in whether the miners re-spread the fines or organic matter over the disturbed site. If that happens, there’s a better chance of successful recovery because it’s very hard to grow tundra or boreal forest in gravel. I’m optimistic about the potential for the AIM protocol to act as an archival dataset for these disturbed regions and to better inform land management decisions.
References
(1) Resource Development Council. Alaska’s Mining Industry. http://www.akrdc.org/mining accessed 8/24/2016.