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Jeff Skousen, Mac Burnett, Dave Bassage, Courtney Black, Paul Ziemkiewicz, and Dave Zucker
Table 1. Representative water quality data for several locations within the Sovern Run Watershed during 1992-1994.
A Potential Solution-Filling Deep Mine Portals with Limestone
Water Quality Before and After Mine Sealing at Sovern Run
Further Projects for Sovern Run Watershed Improvement
Table 2. Water quality measurements at deep mine location #7 in Sovern Run
Acid mine drainage (AMD) coming from abandoned mine lands has become a major priority for many individuals, communities, and resource management agencies in the Appalachian region. The most complex task associated with AMD from abandoned mine lands is finding a cost effective strategy for AMD amelioration and water cleanup. By definition, abandoned mined lands were mined, left in an inadequate reclamation status and abandoned before August 3, 1977, with no continuing reclamation responsibility by any individual or company under state or federal laws. Because abandoned mine lands are exactly that, abandoned, implementation of an AMD prevention or treatment technique that does not require continual chemical additions or maintenance is critical.
While many active treatment technologies are available and effective for treating AMD, the cost of chemicals for treatment, installation of metering equipment, and constant maintenance make the process too expensive for most landowners or watershed associations to accept. Therefore, the formation of strong associations or partnerships with the potential of generating funds through applicable federal and state programs may be used to develop strategies for ameliorating AMD on a watershed level.
One such association has recently been organized for the Cheat River Watershed (Figure 1). This association, Friends of the Cheat, recognized that a long term mission of sustainable environmental health for the watershed could only be achieved through participation of a broad base of stakeholders. The group recruited businesses, property owners, recreational users, local and state elected officials and residents to help chart a course for the future of the watershed. The mission of the organization is "to restore, preserve, and promote the outstanding natural qualities of the Cheat River watershed."
With its organization, Friends of the Cheat coordinated the development of the River of Promise Shared Commitment, a group of state and federal agencies, conservation groups, and industry committed to restore and manage the Cheat River's natural resources in harmony with and to the benefit of the area's human resources. A Shared Commitment document was signed at the first Cheat River Festival on May 6, 1995, and now includes 23 signatories.
The first result of the River of Promise was a $200,000 anoxic limestone drain installed by Anker Energy on Greens Run, a Cheat tributary in the summer of 1995 (see Green Lands 26:26-29, 1996 Summer issue). Other tributaries of the Cheat have been identified as pollutant sources to the Cheat and their contributions to total acid load have been estimated (Titchenell and Skousen, 1996). The formation of this organization has focused attention on AMD problems in the Cheat and initiated avenues for improvement. It has brought together people who often hold divergent views on resource conservation and development into a cohesive group with a common goal.
Sovern Run is a small tributary of Big Sandy Creek, and Big Sandy Creek flows into the Cheat River near the Preston and Monongalia County border. The Sovern Run watershed is located at the northwestern boundary of Preston County near Valley Point, WV, about 15 miles east-southeast of Morgantown, WV (Figure 2). The perimeter of the watershed is 11.0 miles in length encompassing an area of roughly 6,000 acres. With a incline toward the northwest, the watershed drains from 2100 feet in the southeast to Big Sandy Creek at 1300 feet in the northwest.
Sovern Run is classified as a permanent second order, lotic (flowing water) aquatic ecosystem. The main channel of Sovern Run is about 4.7 miles in length, while the total length of the main channel plus permanent and intermittent tributaries is 6.6 miles. The left fork of the headwaters originates at about 2100 feet from a vegetated, emergent wetland, while the right fork begins from several springs at about 2000 feet. After these two tributaries join, the stream encounters larger amounts of surface runoff from nearby surface mines and farms, and receives the discharge from several small deep mines.
The surface geology of the watershed is primarily from the Allegheny group of the Pennsylvanian system, which is composed of massive, coarse-grained sandstones, some sandy shales, and one commercially-important coal bed. The mining history of this watershed dates back to the 1940's. The Upper Freeport coal bed is approximately 4 feet in thickness at this location and several small, contour surface mines and numerous, small deep mines occur at higher elevations in the watershed. The Upper Freeport coal is widely known as an acid-producing coal bed in this vicinity. A recently-closed deep mine treats water with anhydrous ammonia in the right fork of the headwaters.
Information and data on water quality were collected from various agencies and individuals on many points in the watershed. Upon compiling the data and not knowing exactly how the water samples were taken and analyzed, WVU researchers began collecting water samples for analyses in 1989. Walking the entire length of the watershed and collecting water samples at all point sources and at various locations in the stream revealed that several significant sources of AMD were input to the stream. Continued sampling and analysis over the next three years confirmed our findings.
Two deep mine discharges were located in the watershed with each having very poor water quality (Table 1). One is location #7 (Figure 3) and the other is location #8. These sources along with poor water quality coming from unreclaimed land and coal refuse piles degrade the quality of water in Sovern Run. At point #5 after the majority of the AMD from all sources has entered the stream, the pH of the stream is around 3.4 and the acidity concentration varies between 230 to 350 mg/L. Throughout the remaining length of the stream, unpolluted water enters Sovern Run from small streams and surface runoff.
|Table 1. Representative water quality data for several locations within the Sovern Run Watershed during 1992-1994.|
|1 Mouth of Sovern Run||800-2200||3.7||150||6.0||1||220|
|2 Big Sandy Creek Above Sovern Run||???||6.3||0.01||0.6||0.5||55|
|3 Big Sandy Creek Below Sovern Run||???||5.2||0.22||4.2||0.8||115|
|5 Sovern Run After AMD Entered||500-1000||3.4||250||19.0||2.5||330|
|7 Deep Mine Discharge||10-80||2.8||430||45.5||37.0||825|
|8 Deep Mine Discharge||20-60||3.6||750||75.0||48.0||1120|
Sovern Run discharges into Big Sandy Creek, a potential smallmouth bass (Micropterus dolomieui) fishery and a put-and-take trout (Salmonidae sp.) stream. Big Sandy Creek is a spectacular stream. It has a series of 10- to 20-foot falls and is one of the premier whitewater kayaking and rafting streams in the eastern United States. It is used extensively by hikers, mountain bikers and picnickers. Unfortunately, during its lower 6 miles and most potentially beautiful stretch, it is a dead stream.
Due to the input of Sovern Run, even with dilution from incoming streams and runoff, Big Sandy Creek suffers a drop in pH from 6.3 to 5.2 and a 20-fold increase in acid concentration. Aluminum increases from 0.6 mg/L in Big Sandy above the confluence of Sovern Run to 4.2 mg/L downstream of the confluence. This increase in aluminum concentrations in Big Sandy Creek after Sovern Run enters the stream effectively kills the fish population for the lower 5.5 miles of the Big Sandy. The West Virginia Division of Natural Resources estimates that if the acid coming from Sovern Run is ameliorated before it discharges into Big Sandy Creek, the lower 5.5 miles of Big Sandy can be resored to its full potential as a fishery.
A Potential Solution - Filling Deep Mine Portals With Limestone
Knowing that several deep mine portals were discharging AMD into Sovern Run, remedial technologies were sought for treating these discharges. In 1995, a pneumatic stowing device developed by Burnett Engineering, Inc. was used to seal the #7 deep mine portal in Sovern Run with 120 tons of ¾-in sized limestone. The purpose of this project was threefold. First, an improved underground mine filling system for correcting potential mine subsidence problems was demonstrated. Second, a hazardous open portal was sealed to public access. Third, limestone filling of underground mines may effectively reduce or eliminate acid run-off from the mine discharge.
A drawing of the Pneumatic Pipefeeder is shown in Figure 4. The Pneumatic Pipefeeder is a simple and inexpensive pneumatic stowing tool with no moving parts. Fill material is metered into the hopper of the Pipefeeder at a controlled rate. The material fed to the Pipefeeder hopper falls through and is intercepted by the flow of a high velocity jet of air. Air is supplied to the Pneumatic Pipefeeder at 100 pounds per square inch (psi) and expands to pipeline pressure of 4 psi or less (a function of total air flow, solids flow, pipe diameter and pipe length). During this expansion, the air velocity is accelerated to 1,600 ft/sec and, after mixing with the solids and air velocity, is reduced to the pipeline velocity of 120 to 150 ft/sec. The average material velocity after it has been accelerated is about one-half the air velocity. Figure 5 shows the distance material can be transported for various pipe lengths and air and material flow rates.
The material velocity is 60 to 120 ft/sec in a 6-in diameter pipe when 100-psi air is supplied at 1,500 ft3/min to 2,000 ft3/min. The material exits the pipe, which can be up to 300 ft long, and is cast up to 70 ft from the pipe end, depending on the angle of the pipe end to the ground. Typical material flow rates range from 25 st/hr to 50 st/hr depending on the air flow available and the pipeline length. Figure 6 shows the relationship between throw distance and mine height. The pipe outlet must be angled upward to maximize the distance thrown. The optimum angle of the pipe at the exit varies with different mine heights. Higher mine entries or room heights result in longer material throw distances.
The Sovern Run portal is shown in Figure 7. The mine and surface is owned by John Peasley who lives on the property. The mine portal was easily accessible and had evidence of roof falls. The roof had caved at the opening causing the bottom of the opening to be at the original level of the roof. Beyond the opening, the floor dropped about 3 ft to the original floor. The fall at the opening had backed up water in the mine to a depth of 3 ft. Due to the slope of the entry, the water depth at 40 ft inside the entry decreased to less than a foot deep. Water quality exiting the portal had been monitored for two years and had a pH of 2.8 and acidity values of 450 mg/L. The mine therefore was not only a danger to the public since it was open at the face, but it was also draining highly acidic water.
The Pipefeeder was located near the portal with a 6-in diameter pipe extending 30 ft into the portal. Figure 8 is a view of the portal and the pipefeeder setup. A conveyor belt fed the gravel to the hopper of the Pneumatic Pipefeeder at a steady rate which was controllable from the conveyor. A front-end loader kept the conveyor hopper filled from stock piles of ASHTO number 57 limestone. Two 825 ft3/min, 120 psi air compressors in parallel were used to power the Pneumatic Pipefeeder. Based on entry into the mine, the pipe was pushed as far as possible into the entry from the outside to about 30 ft. The pipe was shortened as necessary as the portal was filled with limestone by removing pipe sections until the gravel face reached the face of the portal.
The Pneumatic Pipefeeder and 50 ft of pipe were installed at the entrance of the mine by two people in approximately 15 min (Figure 9). The conveyor rented for the project took 2 hr to set-up. The compressors were parked on the road above the portal with a hose dropped down through the brush to the Pneumatic Pipefeeder. A small crawler tractor with a front-end loader was used to feed material into the conveyor hopper. The equipment setup was completed by 5:00 PM on Monday, 15 May 1995. Stowing was started and 60 tons of ASHTO number 57 limestone gravel were stowed in the mine by 6:45 PM. With half of the gravel placed on the first day, the system was not operated again until a demonstration of the equipment took place for interested parties on 17 May 1995. The stowing was restarted upon arrival of the visitors. During the demonstration, the portal was filled out to the opening and completely sealed in about 1¾ hr (Figure 10). A total of approximately 120 tons of limestone was stowed in the mine void.
Water Quality Before and After Mine Sealing at Sovern Run
During 1992 to 1994, the quality of water draining from the Sovern Run Mine varied between pH 2.7 to 3.0 and acidity concentrations ranged from 260 to 570 mg/L. Iron concentrations were between 11 to 60 mg/L, while aluminum concentrations varied between 30 to 58 mg/L. Flows ranged from 5 gpm to >80 gpm (Table 2).
After stowing 120 tons of limestone in the portal, water quality improvements were seen for a short time. Water pH increased from 2.8 to 5.3 immediately after backstowing, then stayed at pH 6.0 for the ensuing seven months. Acidity concentrations were decreased from an average of 458 mg/L to 42 mg/L, and alkalinity increased from 0 mg/L to an average of 57 mg/L. During the eight months after sealing, there appears to be a trend of decreasing alkalinity generation by the limestone.
Starting in January 1996, very high flows caused the water to flow out at the top of the limestone. As evidenced by the water quality, very little of the water contacted the limestone for treatment, and it has largely returned to its pre-stowing quality. Small amounts of floc and thin coatings of iron hydroxides were found in and on the limestone when limestone was excavated from the portal.
Further Projects for Sovern Run Watershed Improvement
Friends of the Cheat has recently submitted a proposal to the Environmental Protection Agency for funding to install several passive treatment systems in Sovern Run. The primary emphasis of this proposal was placed on enhancing metal precipitation from AMD and reclaiming abandoned lands. Initial designs were presented in the proposal, but final approval of the treatment systems and land reclamation designs will be done by the River of Promise Shared Commitment Committee.
The proposal calls for reconstruction of a settling pond at the #7 deep mine portal entrance. The pond is currently filled with sediment and metal floc from decades of accumulation. This sediment will be dredged out of the pond and used as soil material, and the pond will be enlarged to facilitate removal of metals in the AMD. Limestone rock will also be placed above the mine portal to stabilize the soil and prevent future sedimentation. An abandoned refuse pile near the mine portal, which contributes coal refuse and sediment to the stream, will also be graded, topsoiled with dredged materials, and revegetated. Limestone rock will also be placed in the stream from the pond to the main stem of Sovern Run. Again, final designs await approval by the Committee.
|Table 2. Water quality measurements at deep mine location #7 in Sovern Run|
In addition, Sovern Run has been selected for potential funding by the Acid Drainage Technology Initiative (ADTI), a watershed restoration program administered by the USDI, Office of Surface Mining. Based on preliminary designs and proposals, passive treatment systems will be constructed in the watershed to reduce the acid load in Sovern Run. Three open limestone channels and a large anaerobic wetland are recommended to be installed. The open limestone channels will be built along stretches of stream coming from deep mine portals #7 and #8, and also along a stretch of stream in the right fork of the main stem of Sovern Run. A wetland will be constructed just downstream of site #5 where adequate space exists for a 2.5 acre development. The wetland will enhance wildlife value in the watershed, while enhancing AMD treatment and filtering of metal flocs. Should additional treatment be required to meet target metal loads for fish populations in Big Sandy Creek, limestone sand may be added to the upper reaches of Sovern Run at periodic intervals.
These proposals and future possibilities for water quality improvement in Sovern Run and the Cheat River are a direct result of the development and active involvement of a watershed association. Partnerships of individuals, government agencies, industry and business sharing a common goal for environmental cleanup can bring manpower and resources to problems that previously had no solution.
Burnett, M, and J. Skousen. 1996. Injection of limestone into underground mines for AMD control. p. D-1 to D-5. In: Proceedings, Seventeenth West Virginia Surface Mine Drainage Task Force Symposium, April 2-3, 1996, Morgantown, WV.
Zucker, D.A., J.G. Skousen, T.T. Phipps, and J.J. Fletcher. 1992. Development of a method for the watershed approach to acid mine drainage abatement. p. 537-537. In: Proccedings of the 1992 Meeting of the American Society for Surface Mining and Reclamation. Duluth, MN.
Titchenell, Troy, and Jeff Skousen. 1996. Acid mine drainage treatment in Greens Run by an anocix limestone drain. p. I-1 to I-11. In: Proceedings, Seventeenth West Virginia Surface Mine Drainage Task Force Symposium, April 2-3, 1996, Morgantown, WV.
Figure 1. The Cheat River Watershed. The upper portion is above Parsons. The middle portion extends between Parsons and Rowlesburg. The lower portion is between Rowlesburg and Cheat Lake.
Figure 2. Topographic map of the Sovern Run Watershed. Points 1 through 8 are water sampling locations. Shaded areas are partially reclaimed surface mines.
Figure 3. The #7 deep mine portal in Sovern Run. Acid water flows from the portal into a small pond, then eventually into the main stem of Sovern Run.
Figure 4. Diagram in the text.
Figure 5. Diagram in the text.
Figure 6. Diagram in the text.
Figure 7. Diagram in the text.
Figure 8. View of the Pneumatic Pipefeeder, the conveyor belt, and pipes extending into the mine portal approximately 50 feet.
Figure 9. The pipefeeder is portable and can be installed by two people in a short time.
Figure 10. Filling of the deep mine portal by the Pneumatic Pipefeeder to the portal face. About 120 tons of limestone were blown into the mine.