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DISCHARGE WATER HANDLING AND TREATMENT: PROBLEMS AND SOLUTIONS AT A LARGE 

PITTSBURGH SEAM COAL MINE 

J. D. Byars

RAG Emerald Resrc(s) LP 

Waynesburg, PA, USA 

T. P. Mucho

NIOSH

Pittsburgh, PA, USA 

R. L. Zick

US Filter Opg Svc(s)

Moon Township, PA, USA 

ABSTRACT 

Recently, a large Pittsburgh seam longwall mine 

was nearing depletion of a major portion of its 

current reserves and had begun to develop in a 

different direction from its original portal area to 

access additional reserves. This meant that a large 

area of the mine would be abandoned and sealed. 

However, continued use of the original mine portal 

area required that the water accumulating in the 

abandoned mine would eventually need to be 

pumped to the surface. This would be in addition to 

the discharge water associated with the new portion 

of the mine. Several pumping and sump options 

were investigated to handle the quantity and quality 

of the anticipated discharge water. This paper 

describes some of these options, their advantages 

and disadvantages, and the final engineering 

decisions. Some problems and unanticipated 

outcomes, as well as the eventual solutions are 

discussed, including: (1) estimates of pump 

requirements, (2) water pool size, (3) eventual water 

quality, (4) anticipated inflows, and (5) integration 

into the overall mine water system. 

INTRODUCTION 

The act of creating openings and subsiding strata 

during coal mining almost always produces inflows 

of unwanted ground water. These water inflows into 

the underground mine sometimes present 

considerable problems to mine operators. 

Depending on amounts and location of inflows, the 

water needs to be removed from active mining 

areas. Environmental concerns, law, and regulation 

require coal mines only to discharge water of an 

acceptable water quality. However, contact of the 

ground water with contaminates in and around the 

coal seam, especially minerals such as pyrite, often 

requires costly water treatment facilities to meet 

current criteria. As a result, many operators choose 

to store as much water in abandoned portions of the 

mine and/or use this discharge water in the coal 

preparation process, which can minimize or 

eliminate treatment costs. Due to abandoning a 

major portion of a large Pittsburgh seam longwall 

mine, one operator was challenged to devise a new 

handling system to deal with the accumulating water 

in the abandoned portion and the eventual inflows 

from the projected future mining areas. The 

following describes the engineering processes that 

resulted from the initial evaluation and actual 

outcomes of the collection, pumping, and treatment 

systems. 

BACKGROUND 

The mine is located in Waynesburg, Greene 

County, Pennsylvania, west of the Monongahela 

River in the extreme southwestern corner of the 

state. The mine geology is relatively simple. 

Structurally, the area is dominated by gentle folding 

represented by the Waynesburg Syncline to the 

southwest and the Belle Vernon Anticline near the 

center of the reserve area. Axes of these folds are 

oriented N 40 degrees E and the dips are gentle 

ranging from 0 degrees at the crests and troughs of 

the folds to nearly 2 degrees on the western limb of 

the Belle Vernon Anticline. The Pittsburgh No. 8 is 
2 

the lower member of the Pittsburgh Formation of the 

Monongahela Group and generally occurs at about 

600 feet below the surface. It is characterized as a 

major coal seam varying from 0 to 12 feet. 

However, it averages 6.0 to 7.0 feet in thickness 

over most of the reserve area and gradually 

increases in thickness to the east of the reserve. A 

major sandstone channel is present across the 

reserve between the portal area and the new 

reserve. The mine currently utilizes one longwall 

section and several development sections. The 

Pittsburgh coal seam in the general area dips in the 

western direction. As the mine began to deplete 

their reserves in the southern area, the mine 

developed the new reserves in the eastern direction. 

The mine had previously sealed the western portion 

of the mine in the early 90’s, south of the main 

portal. This area is the lowest elevation in the mine. 

The relative locations of these areas are depicted on 

the map in Figure 1. The western area that was to 

be sealed is approximately 7,270 acres (11.4 square 

miles). The mine sealed the southern end of the 

mine near the number 1 portal. These seals 

adjoined the western seals and thus sealed off a 

majority of the depleted reserves. Sealing of the 

depleted reserves allowed the mine to use the 

sealed area as a water storage area. The mine had 

been utilizing the western sealed area as a natural 

sump or water storage area since the early 90’s. 

This system was convenient for water handling. 

The general quality of the active mining discharge 

water was acceptable for discharge. However, it 

was suspect due to the short residence time prior to 

being pumped out the mine. Water samples in the 

sealed area were taken at an abandoned capped 

shaft and the results of these analyses also 

indicated good quality water. 

Prior Operating Plan 

As the current mine dewater system became 

unable to handle the total mine discharge, new 

options were considered for the removal of mine 

water. The new pumping system design had to 

encompass many design considerations. Some of 

the considerations are listed below: 

• Safety and operational risks 

• Water system integration 

• Future mine plan design 

• Minimize operating and capital investment 

• Maximize efficiency and minimize 

operational delays

 Figure 1 Mine Map With Flow Diagram 
3 

The existing pumping system, consisting of a 

small, above-mine floor storage sump, and the #1 

sump pumps located at the main portal area, was 

delivering about 300 gpm of water to the surface. All 

of the water pumped to the surface was collected in 

a series of ponds and then used by the coal 

preparation plant as make-up water. Water from this 

sump was the only water pumped from the mine with 

the nearby sealed area accumulating the remainder 

of the mine make of ground water. This original 

system had a number of problems. The #1 sump 

was small and the system was under-designed to 

handle the amount of water and solids that was 

being developed. The system was down frequently 

due to maintenance problems requiring the water to 

be directed to the abandoned workings behind the 

western seals. This original sump was limited in size 

and would fill up with solids periodically. The high 

head pumps would only last several months, due 

primarily to the abrasive material in the water. The 

discharge line to the surface would burst on an 

average of six times a year because of the high 

head and the age of the line. Also, the #1 sump was 

very inefficient and required a high amount of 

maintenance to remove accumulated solids. After a 

cursory evaluation, other system options were 

investigated. 

Determining Requirements of Pumping System 

Prior to the design of a pumping system, a general 

flow diagram was developed (Figure 1). The data 

for this diagram was gathered in several ways. The 

ground water inflow behind the seals was 

determined by a meeting with several foremen that 

managed the water when the mine was active in that 

area. The foremen indicated that the water flow, 

after the initial mining, was fairly consistent at 

approximately 300 gpm. The water inflow, pumped 

via pipeline from the southern end of the mine, was 

approximately 350 gpm. The water from the active 

eastern reserves was determined to be about 150 

gpm. The total maximum projected flow was 

calculated to be 800 gpm. An 1100 gpm flow rate 

was selected for the design flow. The 1100 gpm 

flow rate allows for approximately a 33% increase on 

the total flow. 

Using a piezometer, water levels were taken from 

the abandoned shaft to record the water elevations 

in the sealed area. An attempt to calculate the water 

inflow rate into the sealed area using the water level 

increase was difficult. The natural sump, located 

behind the western seals, had several sources of 

water inflow. This area was the natural low spot of 

the mine and consisted of previously retreated room 

and pillar, longwall panels and associated standing 

entries. Inflows of natural ground water and 

discharge from active mining areas pumped via a 

pipeline system into the area, accumulated there. 

Theoretically, the groundwater inflow rate could be 

calculated by documenting the rise in water level in 

the sump and subtracting out the known mine 

discharge inflow. However, the required data is very 

difficult to obtain. This is due to difficulty 

determining the volume of the sump given the 

caving and remaining pillars. 

A reasonable approximation can be made of the 

volume of the standing entries. However, 

determining the volume in the caved areas is more 

speculative. This is due to problems obtaining the 

height within the caved area, which can be filled with 

water, and estimating the void space within the 

broken rock in the gob. The gob void space 

calculation was attempted using the following 

analysis: The gob was defined in area to originally 

have a 7-ft mining height. It was assumed that the 

main contributor for sump capacity in the gob area 

would be the “caved zone” area as depicted by Peng 

and Chaing and Singh and Kendorski1,2. The 

contribution of the “fractured zone” and other 

subsided areas of the gob were considered to be 

negligible. The height of the caving zone can be 

estimated by formulas and bulking factors given by 

Peng1

 and Chen3. In this case, a caving height of 5 

times the mining height and a bulking factor of 1.25 

were used. This results in a maximum water fill 

height of 35 feet from the original bottom with 25% 

of this volume being available for water storage. 

This calculation could be assumed across the width 

of the longwall panel and added to the volume of the 

standing entries. Therefore, at various water pool 

elevations, and given the original coal bed bottom 

elevations, the total water storage volume available 

could be estimated at incremental, measured, sump 

pool heights. 

The main point of determining the volume of the 

inflow into the sealed area was to develop a good 

engineering estimate of the total flow rate that would 

need to be pumped. While a reasonable estimate 

was made, the ground water inflow rate of the 

sealed gob was very difficult to determine precisely 

by this volume method. 

Two General Options 

There are two general locations that the water can 

be pumped out of the mine. The first is the active 

area of the mine. The second is the sealed area of 

the mine. The barriers between these two areas are 

ventilation seals. Under 30 CFR part 75 ventilation 

seals cannot be used to bulkhead water. This 

requirement prevents water flow from the sealed 

area to the active area by gravity flow methods. The 

main objective was to remove water from the sealed 
4 

area and active area with the lowest overall cost. 

There are many constraints that one must satisfy 

prior to project commencement. The problem 

solution is classified by Option 1 and Option 2. 

Option 1: Option 1 included constructing a new 

sump at the bottom of the main portal area. The 

new sump location was targeted near the bottom of 

the shaft. The scope of the new sump would include 

installation of a borehole to pipe the water to the 

surface, new pumps, and increased sump storage 

capacity. The borehole would replace the old line 

that was encased in the concrete floor in the slope 

track entry. The borehole was selected in lieu of 

running a new pipe down the track or belt entry of 

the mine slope. The pump design was driven by 

water samples taken of the existing discharge water. 

A water analyst classified the sample as highly 

abrasive. Horizontal centrifugal split case pumps 

were selected due to the high abrasive properties of 

the water. This approach was conservative 

considering that the water would have a longer 

retention time to settle suspended solids. The 

increased sump size was designed to increase the 

time for the solids to settle. The sump was designed 

as a dual compartment sump to allow pumping in 

conjunction with sump cleaning. The new sump 

design encompassed all the requirements of an 

efficient underground sump but still required periodic 

pump maintenance and cleaning of the sump. The 

borehole water would still be pumped into the series 

of ponds and then be utilized as preparation plant 

makeup water. The new sump would handle the 

water from the active area while an additional pump 

would be required to discharge the water from 

behind the seals. 

Option 2: Option 2 considered using the sealed 

area as a natural sump. The sealed area has some 

inherent advantages and disadvantages associated 

with its use as a main sump. The natural sump has 

more available storage area for groundwater and 

active area water storage. The water quality 

appeared sufficient for use in the coal preparation 

plant as well as for underground. A benefit of having 

the additional water available is water interruption 

insurance and as an offset for city water purchases. 

The water from the sealed area would compliment 

the water system with the ability to store water and 

supply water when the preparation plant required 

additional make up water. Storage capacity is also 

very important to the operation in times of high water 

demand and periods of drought, which has affected 

the city water supply in the past. The pump design 

in the natural sump area assumes that the water in 

the sealed area would settle a majority of the 

abrasive solids. Permitting the solids to settle out in 

the sealed area would eliminate the material 

handling problems and sump cleaning problems 

associated with Option 1. The use of the natural 

sump as the main sump would, of course, also 

eliminate the need for construction of the new sump. 

However, placement of the pump is more difficult in 

this option because this area is not in an active area 

of the mine. Optimum sites for pump placement 

were limited and remote from the surface water 

system. A concern with this option was that the 

water quality data for the natural sump was limited 

and could be different than the sampling results 

indicated. 

Pump Placement and Design 

There were two options for the placement of the 

pump in the sealed area. The pump could be placed 

in the capped mine shaft or in a drilled borehole. A 

cost-benefit analysis was completed on the locations 

in question. Placing the pump in the shaft had 

several obstacles to overcome. The shaft was 

approximately one mile away from the main water 

system and the surface pipeline to the ponds would 

need to cross Tenmile Creek, a Norfolk Southern 

railroad line, and several non-owned properties. 

This option actually was less risky than placing the 

pump in a drilled borehole. Drilling a borehole into 

sealed area of the mine can be very difficult because 

the exact underground location cannot be explored. 

Since the shaft already existed, placing the pump 

into a shaft would be less problematic than a 

borehole. The cost of installing the pipeline from the 

pump/shaft location to the discharge point was the 

item that made the shaft option unfeasible. The 

placement of the pump in a borehole that could be 

placed nearer the surface ponds was determined by 

the mine as the most viable option. 

The borehole was located on the western side of 

the mine property at an intersection of the mine 

entries adjoining solid coal in anticipation of greater 

borehole and opening stability. The overburden in 

this area was 800 feet. Pump design limited the 

choice of pump type to a vertical turbine line shaft. 

The line shaft pump was designed to set 805 feet 

into the mine. The surface pipe was designed to 

flow into either of two make-up ponds for the 

preparation plant. Figure 1 depicts the location of 

the pump borehole relative to the underground 

workings. 

The final consideration in the pump design is the 

construction materials selection. Water samples that 

were taken in the abandoned airshaft indicated that 

water was normal groundwater. There was no 

special material pump material required for the water 

quality that was sampled. It was anticipated that the 

water samples may not be representative of the 

entire sump. The different types of material 

construction ranged from cast iron to stainless steel. 

The stainless steel construction was two times the 
5 

cost of cast iron. Cast iron was selected for the 

material construction due to the cost differential. 

Conclusion of Collection/Pumping Options 

Option 2, using the abandoned area as the main 

storage sump and pumping through a borehole, was 

selected because it was the most economical and 

overall had less inherent risk. The design was 

confirmed and project timeline was constructed. At 

that time the water level in the sealed area was 

rising fast and the water was expected to reach the 

ventilation seals within three months. The project 

schedule was very critical to operation of the mine. 

A specification was written and contract was placed 

with a local drilling contractor. 

Actual System Operation 

The project experienced a few delays but was 

completed on schedule. The pump was set and the 

pipe was installed to the coal preparation plant 

storage ponds. The system was put into operation 

and water samples were taken. The field pH of the 

water was 5.7, which was lower and more acidic 

than expected. Iron levels were also unexpectedly 

high in the range of 2,000 ppm. Visually, besides 

these obvious parameters, other aspects of the 

water appeared normal. The water quality deviation 

was considered to be a combination of the sampling 

method and possibly the contact of the water with 

the concrete shaft lining. Also, the water may have 

been stratified taking the agitation with the 

commencement of pumping to provide a more 

representative sample of the overall water quality. 

The water quality indicated that treatment was 

necessary prior to discharge or use in the 

preparation plant. The results of the analyses are 

tabulated in Table 1. 

Table 1 Mine Water Quality 

Parameter Result Units 

pH, field 5.7 S.U. 

Alkalinity 240 mg/l as 

Acidity (Hot) 2,400 mg/l as 

Total Suspended 200 mg/l 

Total Dissolved 24,000 mg/l 

Sulfates 12,000 mg/l 

Iron, Ferrous 1,950 mg/l 

Iron, Total 2,000 mg/l 

Manganese 10 mg/l 

Aluminum <1 mg/l 

Chloride 3,500 mg/l 

Sodium 4,500 mg/l 

Calcium 350 mg/l 

Magnesium 490 mg/l 

Osmotic Pressure 410 MOS/KG 

Investigation of Water Treatment Methods 

Upon recognition that water treatment would be 

required, a simple caustic soda (NaOH) storage and 

feed system was initially installed to operate on a 

temporary basis. The injection point for 50% NaOH 

was just below the overflow from one of the make-up 

water storage ponds which cascaded down a rock 

ditch to the fine refuse tailings pond. This treatment 

system provided satisfactory results for pH 

adjustment without the need for automatic control. 

Because of the large retention time in the slurry 

impoundment, adequate aeration was provided to 

oxidize the ferrous iron. However, the chemical cost 

was extremely high, which led an investigation to 

alternative treatment methods. In addition to the 

high chemical cost for treatment with caustic soda, 

there were problems associated with the sludge 

particles due to the fluffy nature and the very low 

density of the settled sludge. The fine refuse tailings 

pond, where this sludge accumulated, is designed to 

return water back to the coal preparation plant to be 

used as make-up water to pump the slurry from the 

thickener underflow to the impoundment pond. 

Therefore, the light floc particles, created from a 

caustic soda treatment system, would present long 

term problems for the return water quality. 

A refined actual groundwater inflow rate was 

needed for the water treatment plant design. This 

further analysis of the flow rate was needed prior to 

making the high capital investment for water 

treatment facilities. Also it was thought that the 

water quality from a larger zone would need to be 

determined to be sure the early samples were 

representative of the large body of stored water. A 

pumping test was setup with two objectives. The 

first objective was to determine groundwater inflow 

rate and the ability of the current pumping rate 

capacity to adequately lower the water elevation in 

the sump, given the existing inflows. The second 

objective was to determine whether any changes 

would occur to the water quality over a longer 

pumping period. The test was setup for a two-week 

period. This pump period was thought to be 

adequate to determine if the water quality was going 

to change over time. The inflow rate was 

determined by following parameters: 

• Assume a constant vertical volume in the 

sealed area. 

• Assume ground water inflow equal to the water 

pumped minus inflow from active area. 

• Pump rate of 1,100 gpm. 

• Active area inflow equal to 100 gpm. 

• Change in depth while pumping. 

• Change in depth while pump shut off. 
6 

• Time the pump is pumping. 

• Time the pump is shut off. 

This constant vertical volume method was chosen 

as the only reasonable method that could measure 

the actual ground water inflow rate. The test method 

was to operate the pump and measure the time in 

which the water elevation drops. Then shut the 

pump off. The amount of time for the pump to lower 

the water level a predetermined distance was 

measured. The following table 2 is the test that was 

performed prior to determining a water treatment 

plant design flow rate. 

Table 2 Dewater Pump Flow Rate Test 

Q1= 1100 Pump Rate(gallons/minute) 

Q2= 335 Groundwater Inflow(gallons/minute) 

Q3= 100 Mining Water Inflow(gallons/minute) 

D1= 1.27 Change in Depth While Pumping(feet) 

D2= 1.04 Change in Depth while Waiting(feet) 

T1= 5760 Time the Pump is running(minutes) 

T2= 7200 Time the Pump Shutoff(minutes) 

Total GPM 435

The pump test indicated the ground water inflow 

rate was 335 gpm. The equation for Table 2 is as 

follows: 

T1*D1*(Q1-Q2-Q3)=T2*D2*(Q2+Q3) 

This equation is simply a flow balance equation. 

Verification of the actual ground water inflow rate 

indicates that the pump met the required flow rate. 

The total flow rate as seen in Table 2 is 435 gpm. 

This total flow rate also indicated that the pump rate 

is not too excessive. However, the pump still 

needed to be replaced since the pH was below 7. 

An order was placed on a stainless steel pump to 

reduce the operational risk to the pumping system. 

The water quality variation over the two-week pump 

period was minimal, indicating that no significant 

change in quality was expected in the future. 

Therefore, the water treatment facility was designed 

as per the data in Table 1. 

Lime Treatment System 

It was decided to evaluate the alternative concept 

of a lime treatment system. The capital, operating 

and maintenance costs for an installed lime 

treatment system were determined and compared to 

similar costs for a caustic treatment system. A 

preliminary budget cost for an installed lime 

treatment system was provided by Chester 

Engineers. A tabulation of all the costs for these two 

treatment systems provided the data required to 

compare the internal rate of return. On this basis, 

the lime treatment alternative provided a return on 

investment in less than one year. 

To provide support to justify the preliminary 

tabulation discussed above, bid specifications were 

prepared, submitted to qualified bidders and 

proposals received. A design/build contract was 

awarded to the most qualified bidder based on 

evaluated costs. 

The basic treatment process that was selected 

included the following steps: 

1. Pre-aeration: An on-site bench scale treatability 

study was conducted to determine if there would be 

a benefit from pre-aeration of the mine water. Alkali 

requirements were measured initially on the mine 

water without aeration to establish a baseline. 

Additional samples were then aerated at a rate of 

1 liter/minute for 10, 20, 40, 60, 120, and 240 

minutes. The alkali requirements for each were then 

measured in a step titration process identical to that 

which had been completed on the initial sample. 

The findings indicated that there would be a benefit 

from pre-aeration through savings of approximately 

12% of the lime. The lime reduction benefit 

increased steadily through the sample aerated for 60 

minutes and leveled off thereafter. As a check to 

confirm this process benefit, the total inorganic 

carbon was measured on the samples. The initial 

sample contained 97.4 mg/l of inorganic carbon and 

after 60 minutes of aeration, the concentration was 

reduced to 29.8 mg/l. 

Pre-aeration has been utilized in many acid mine 

drainage treatment systems in Southwestern 

Pennsylvania that operate on Pittsburgh Seam Coal. 

Often there is a limestone formation in close 

proximity to the coal seam providing alkalinity to the 

mine water. Pre-aeration of this water drives off the 

CO2 and reduces the carbonic acid content. An 

additional benefit is derived from reduction in 

carbonate scale formation, which would otherwise 

occur on system components. Pre-aeration was 

selected to improve lime utilization and reduce scale 

formation. 

2. Post-aeration: A survey of the most commonly 

used methods to oxidize the ferrous iron in coal 

mine drainage treatment systems showed the 

following types available: 

• Fixed-mount surface aerators. 

• Floating surface aerators. 

• Submerged-turbine aerators. 

• Fixed-mount combined surface/submerged 

turbine aerators. 
7 

For a lime treatment system using a circular 

concrete reactor for this neutralization/aeration step, 

the floating surface aerator concept was eliminated 

due to potential solids build-up within the tank. The 

surface aerator and the combination unit both have 

upper impellers that create a splash effect in the 

tank. To counteract this effect, the freeboard in the 

reactor needs to be increased. Another adverse 

effect from surface aerators is the creation of a fine 

iron colored mist that is easily transported to the 

surrounding area by the wind. To counteract this 

effect a tank cover is normally installed. Because of 

these conditions a submerged-turbine aerator was 

selected as the preferred method for the application. 

There is a slight efficiency penalty to pay according 

to the equipment manufacturers, but operational 

concerns became paramount, leading to the 

decision to select the submerged-turbine type. With 

this method, external positive displacement blowers 

are used to provide the air. They are located in an 

adjacent building that also houses the motor control 

center and the programmable logic controller. 

The submerged turbine aerator system is designed 

to provide an oxygen transfer rate of 158 lb of O2 per 

hour assuming up to 2000 mg/l of ferrous iron and 

1100 gpm of mine water influent. 

3. Lime Silo and Slurry System: Neutralization for 

the mine water is provided through a packaged 50-

ton hydrated lime storage, feed, and slurry system. 

The system includes the following components. 

• Truck fill line with operator station panel. 

• Silo level sensors for the dry lime. 

• Dust collector. 

• Bin activator. 

• Discharge isolation knife gate valve. 

• Volumetric screw type feeder for up to 2000 

lb/hr. 

• Lime slurry make-down tank, 1000 gallon 

capacity. 

• Slurry tank mixer. 

• Slurry level sensor. 

• Lime slurry pumps. 

• Silo exhaust fan. 

• Silo electric heater. 

• Silo light fixtures. 

• Silo skirt insulation. 

• Silo panel with indicator lights and 

disconnects. 

From this system a 10% lime slurry is pumped in a 

continuous loop from the lime slurry make-down tank 

with a return back into this tank. Lime slurry from 

this loop is fed into the neutralization/aeration tank 

based on demand. The control system for this 

includes a pH controller, a pH probe, and a 4-20 ma. 

modulating V-notch control valve. A predetermined 

range for the pH setpoints is provided in the 

programmable controller. 

The complete treatment system as described 

provides gravity flow from the pre-aeration tank 

through the post-aeration tank and from there down 

a riprap channel and into the fine refuse tailings 

pond. 

The performance of the system is measured 

essentially by the efficiency of iron conversion from 

the ferrous form to ferric iron. In addition, lime 

utilization is tracked by comparing actual usage to 

theoretical. 

There are no discharges from the fine refuse 

tailings pond and only two NPDES outfalls from the 

entire site. The parameters that are regulated at 

these locations include pH, suspended solids, iron, 

manganese, aluminum, and osmotic pressure. 

SUMMARY 

As this Pittsburgh seam longwall mine proceeded 

to abandon a major portion of depleted reserves and 

mine remaining reserves from its original portal area, 

it was faced with the problem of handling the ground 

water being produced from the abandoned area plus 

the additional water from its future mining. A natural 

sump that had been used to store excess ground 

water over the years was beginning to reach 

capacity and would soon spill over into the active 

portal area. This required that the operator pump 

the all the water being produced from both the 

abandoned and new mining. However, the existing 

pumping system was undersized and faced a 

number of other problems. Several alternatives 

were analyzed. Based on a number of perceived 

advantages the decision was made to utilize the 

sealed natural sump portion of the mine as a main 

collection area. Two options were analyzed to pump 

from the sealed area, with pump in a borehole 

configuration being the final choice. Attempts were 

made to quantify the pumping system design 

parameters: quantity and any special considerations 

due to water quality. The quantity question was 

successfully estimated and later confirmed by a 

more precise estimation method. However, the 

actual water quality was much poorer than 

anticipated, apparently due to inherent problems 

with the sampling method used to determine the 

quality of the water stored in the sealed area. This 

required a temporary treatment facility until the 
8 

required design of a final treatment facility could be 

determined and procured. Due to acidity of the 

actual water the original cast iron pump needed to 

be replaced with a stainless steel pump. The final 

treatment method chosen was a hydrated lime 

treatment system, which provided an acceptable 

make up water to the coal preparation process and 

worked in concert with that process to result in a 

final mine water cycle which requires little discharge 

of water. The relatively small discharges from the 

system meet the requirements for NPDES 

discharges. 

 1

 Peng, S.S. and Chaing, H.S., 1984, Longwall Mining, John 

Wiley & Sons, New York, 708 pp. 

 

2

 Singh, M. M. and Kendorski, F.S., 1981, “Strata Disturbance 

Prediction for Mining Beneath Surface Water and Waste 

Impoundments”, Proceedings of the 1st Conference on Ground 

Control in Mining, West Virginia University, Morgantown, WV, July 

27-29, pp. 76-89. 

 

3

 Chen, J., Mishra, M., Zabrosky, C., and DeMichiei, J., 1999, 

“Experience of Longwall Face Support Selection at RAG 

American Coal Company”, Proceedings of the Longwall USA 

1999 International Exhibition and Conference, Pittsburgh, PA, 

September 21-23, Coal Age, pp. 53-77.