Site-specific reclamation model

October 2012 » Features » PROJECT CASE STUDY
Improving practices for permanent vegetation establishment at surface mines.
Brian Free, CPESC
One year after seeding, the site-specific reclamation model improved permanent vegetation establishment at a West Virginia surface coal mine.
Photo:Pennington Seed

The Appalachian Coal Basin encompasses multiple mountain ranges, several major river gorges, and numerous state and national parks. Consequently, the region draws visitors from across the country and around the world.

Project
Surface coal mine reclamation, W.Va.

Participants

Alpha Natural Resources Inc.
Pennington Seed Inc.

Project challenge
Soil testing, appropriate seed and soil amendments, and erosion control best management practices address challenge of vegetation establishment at rehabilitated surface mines.

It also is home to one of the most important coal-producing regions in the United States and one of the largest on the globe. Appalachian coal has been mined during the last three generations and is now most commonly used for electrical power generation. Coal mining is economically vital to many rural communities across the basin and is a cornerstone in our domestic energy supply.

The U.S. Environmental Protection Agency (EPA) has authority over mining operations through the Clean Water Act, which identifies mining operations as potential point sources for pollutants and regulates these sites under the National Pollutant Discharge Elimination System (NPDES) permit.

In 2009, Alpha Natural Resources Inc. in Julian, W.Va., approached Madison, Ga.-based Pennington Seed to assist them in their revegetation efforts on reclaimed surface mines. One primary goal of the partnership was to improve permanent vegetation establishment during initial seeding applications to meet permit requirements and to avoid the compounded costs associated with failed revegetation projects. The cost of seeding materials was minimal compared with the total reclamation cost, which included earthmoving and hydroseeding equipment, mobilization, fuel, maintenance, and labor.

Utilizing a collaborative approach between Alpha's environmental managers and Pennington's agronomic team, a more efficient reclamation model emerged. Mine site operators began to coordinate soil tests and analyses with Pennington prior to seeding to allow for site-specific reclamation plans that addressed soil fertility, pH, erodibility factors, seed selection, and erosion control measures. This increased the establishment success rate of permanent vegetation that complemented post-reclamation land uses. The following steps were essential in implementing this new model.

Soil testing
Soil testing prior to seeding is critical on mine sites to help ensure the establishment of permanent vegetation. Depending on the geological profile from which material is mined, the surface soils can vary greatly in composition. Soil organic matter, nutrient availability, and pH can range widely, even within a close proximity on the surface. Acidic conditions can also arise in post-mining operations due to the presence of certain elements and acid mine drainage.

The majority of the sites tested had extremely low levels of organic matter (0.2 to 1.4 percent) since the seed bed was largely comprised of crushed bedrock and shale. Desiring a minimum of 4 percent organic matter to sustain long-term vegetation success, mycorrhiza soil fungi, beneficial bacteria, and multiple bio-stimulants – the building blocks to healthy soil – were applied to the prepared slopes at the time of seeding to address organic matter deficiencies.

Hydroseeding allows easy adjustment of ingredients in the tank mix based on site requirements.
Photo:Pennington Seed

Most soil analyses indicated acidic pH levels with differing inherent nutrient values. Large amounts of lime were required to raise the pH to an ideal range between 6.0 and 6.5, where soil nutrients become plant available. Customized fertility plans also increased reclamation efficiency by eliminating excess fertilizer and the potential for water quality impairment compared with standardized applications.

Seed selection
Much of the seed that Alpha's legacy sites in West Virginia and Kentucky had previously used was not properly labeled and yielded inconsistent results. Third-party seed laboratory tests determined that temporary, annual grasses such as wheat and rye dominated the mixes; permanent perennial legumes, such as birdsfoot trefoil, or yellow blossom clover, were lacking under permit requirements. Vegetation establishment efforts were greatly enhanced by selecting properly labeled seed mixes with guaranteed analysis that complemented permit species requirements.

Because of the steep terrain of the basin and the large tracks of land that needed to be reclaimed, hydraulic seeding or hydroseeding was the preferred seeding method. Hydroseeding offered a distinct advantage over other seeding methods in that the ingredients in the tank mix recipe could be easily adjusted based on soil test results and site requirements. This allowed for implementation of site-specific revegetation plans that could accurately and efficiently address all major obstacles to vegetation establishment at the time of seeding.

Expanding the model
Overburden materials (bi-products of coal processing) often are used to reclaim high walls and valley-fill impoundments. These sites are a particular challenge to vegetate. The common practice for reclaiming these areas is to apply a minimum soil layer of 18 to 24 inches as a "cap" on top of the overburden material prior to seeding. Alpha was impressed with Pennington's previous success record for establishing vegetation directly on fly ash and, as a result, opted to direct-seed the overburden areas. By eliminating the need for a soil layer on top of the overburden material, the potential saving in time and money were enormous.

When analyzed, the overburden material and fly ash were quite similar. They both exhibited low pH and percent organic matter, along with a dark surface color that readily absorbed thermal radiation, making the surface at least 20 degrees F hotter than surrounding soils in the summer. To sustain vegetation, the acidic pH levels were raised with pulverized limestone and fast-acting dry lime. Nutrient deficiencies were resolved with the re-introduction of highly concentrated bio-stimulates, beneficial soil microbes, and fertilizer.

When this approach was implemented at Alpha's Grey Eagle processing site in Mingo County, W.Va., the project team selected a cool-season SLOPEMASTER seed mixture specifically designed for stressed environments and a Mohawk cold-tolerant bermudagrass. The seed mixture was treated with GermMax germination aid to increase seedling vigor during germination and establishment, as well as MYCO Advantage mycorrhiza inoculants to increase nutrient and water absorption and help mitigate drought and salt stress. Starting in March 2011, the seed was hydraulically applied along with soil amendments and 3,000 pounds per acre of a high-performance, fiber-reinforced matrix that effectively stabilized the site from erosion, while also acting as a sunscreen over the dark material to reduce temperatures and evaporation rates.

By the one-year mark, the site had been converted from a 40-acre impoundment of exposed refuse and minimal vegetation to a lush and heavily vegetated site. The dense, permanent vegetation establishment across the site greatly exceeded Alpha's expectations, with the site operator commenting that "the impoundment area looked as lush as a state park."

Lessons learned
The collaborative effort addressed the traditional challenges of vegetation establishment on rehabilitated surface mines, as well as value-enhanced seeding applications on coal refuse and overburden areas. The site-specific reclamation model provided improved best management practices for soil stabilization and erosion control, while dramatically improving permanent vegetation establishment. Starting with a soil test, corrective actions were taken to mitigate soil conditions at the time of seeding to create the right foundation for long-term, sustainable growth.

By utilizing a comprehensive approach that encompassed soil science, agronomy, and improved soil stabilization techniques, Alpha substantially increased vegetation establishment success rates from initial seeding applications. Alpha continues to utilize Pennington in the evaluation of its reclamation best management practices.

Brian Free, CPESC, is business development manager for Pennington Seed, Inc.

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