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Effects of Abandoned Coal-Mine Drainage on Streamflow and Water Quality in the Mahanoy Creek Basin, Schuylkill, Columbia, and Northumberland Counties, Pennsylvania, 2001

U.S. Geological Survey Scientific Investigations Report 2004-5291

By Charles A. Cravotta III

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This report assesses the contaminant loading, effects to receiving streams, and possible remedial alternatives for abandoned mine drainage (AMD) within the Mahanoy Creek Basin in east-central Pennsylvania. The Mahanoy Creek Basin encompasses an area of 157 square miles (407 square kilometers) including approximately 42 square miles (109 square kilometers) underlain by the Western Middle Anthracite Field. As a result of more than 150 years of anthracite mining in the basin, ground water, surface water, and streambed sediments have been adversely affected. Leakage from streams to underground mines and elevated concentrations (above background levels) of acidity, metals, and sulfate in the AMD from flooded underground mines and (or) unreclaimed culm (waste rock) degrade the aquatic ecosystem and impair uses of the main stem of Mahanoy Creek from its headwaters to its mouth on the Susquehanna River. Various tributaries also are affected, including North Mahanoy Creek, Waste House Run, Shenandoah Creek, Zerbe Run, and two unnamed tributaries locally called Big Mine Run and Big Run. The Little Mahanoy Creek and Schwaben Creek are the only major tributaries not affected by mining. To assess the current hydrological and chemical characteristics of the AMD and its effect on receiving streams, and to identify possible remedial alternatives, the U.S. Geological Survey (USGS) began a study in 2001, in cooperation with the Pennsylvania Department of Environmental Protection and the Schuylkill Conservation District.

Aquatic ecological surveys were conducted by the USGS at five stream sites during low base-flow conditions in October 2001. Twenty species of fish were identified in Schwaben Creek near Red Cross, which drains an unmined area of 22.7 square miles (58.8 square kilometers) in the lower part of the Mahanoy Creek Basin. In contrast, 14 species of fish were identified in Mahanoy Creek near its mouth at Kneass, below Schwaben Creek. The diversity and abundance of fish species in Mahanoy Creek decreased progressively upstream from 13 species at Gowen City to only 2 species each at Ashland and Girardville. White sucker (Catostomus commersoni), a pollution-tolerant species, was present at each of the surveyed reaches. The presence of fish at Girardville was unexpected because of the poor water quality and iron-encrusted streambed at this location. Generally, macroinvertebrate diversity and abundance at these sites were diminished compared to Schwaben Creek and other tributaries draining unmined basins, consistent with the observed quality of streamwater and streambed sediment.

Data on the flow rate and chemistry for 35 AMD sources and 31 stream sites throughout the Mahanoy Creek Basin were collected by the USGS during high base-flow conditions in March 2001 and low base-flow conditions in August 2001. A majority of the base-flow streamwater samples met water-quality standards for pH (6.0 to 9.0); however, few samples downstream from AMD sources met criteria for acidity less than alkalinity (net alkalinity = 20 milligrams per liter as CaCO3) and concentrations of dissolved iron (0.3 milligram per liter) and total manganese (1.0 milligram per liter). Iron, aluminum, and various trace elements including cobalt, copper, lead, nickel, and zinc, were present in many streamwater samples at concentrations at which continuous exposure can not be tolerated by aquatic organisms without an unacceptable effect. Furthermore, concentrations of sulfate, iron, manganese, aluminum, and (or) beryllium in some samples exceeded drinking-water standards. Other trace elements, including antimony, arsenic, barium, cadmium, chromium, selenium, silver, and thallium, did not exceed water-quality criteria for protection of aquatic organisms or human health. Nevertheless, when considered together, concentrations of iron, manganese, arsenic, cadmium, chromium, copper, lead, nickel, and zinc in a majority of the streambed sediment samples from Mahanoy Creek and AMD-affected tributaries exceeded the probable effect level for toxicity because of multiple contaminants.

The water-quality data for the AMD sources were used to determine priority ranks of the sources on the basis of loadings of dissolved metals (iron, manganese, and aluminum), net alkalinity, and sulfate and to identify possible remedial alternatives, including passive-treatment options. The ranking sequence for the top AMD sources based on the high base-flow data generally matched that based on the low base-flow data. Although concentrations increased with decreased flow, the pollutant loadings generally increased with flow; six previously identified intermittent AMD sources were not discharging during the low base-flow sampling period. The top 4 AMD sources, Locust Gap Tunnel (M29), Packer #5 Breach (M13), Packer #5 Borehole (M12), and Girard Mine seepage (M11), on the basis of dissolved metals loading in March 2001, accounted for more than 50 percent of the metals loading to Mahanoy Creek, whereas the top 15 AMD sources accounted for more than 99 percent of the metals loading. When sampled in March 2001, the top 15 AMD sources had flow rates ranging from 0.4 to 17.2 cubic feet per second (680 to 29,200 liters per minute) and pH from 3.9 to 6.7. Dissolved iron was the principal source of acidity and metals loading; concentrations of iron ranged from 2.1 to 18 milligrams per liter. Dissolved manganese ranged from 0.95 to 6.4 milligrams per liter. Dissolved aluminum exceeded 1.0 milligram per liter at 4 of the top 15 AMD sources but was less than 0.4 milligram per liter at the others. Nine of the top 15 AMD sources, including the top 4, were net alkaline (alkalinity greater than acidity); the others were net acidic and will require additional alkalinity to facilitate metals removal and maintain near-neutral pH.

Alkalinity can be acquired by the dissolution of limestone and (or) bacterial sulfate reduction within various passive-treatment systems including anoxic or oxic limestone drains, limestone-lined channels, or compost wetlands. Subsequently, the gradual oxidation and consequent precipitation of iron and manganese can be accommodated within settling ponds or aerobic wetlands. Assuming an iron removal rate of 180 pounds per acre per day (20 grams per square meter per day), constructed treatment wetlands at the top 15 AMD sites would require a minimum area ranging from 0.3 to 5.8 acres (1,210 to 23,500 square meters). Land area below the Packer #5 Breach (M13, ranked 2nd of all AMD sources in the watershed), the Packer #5 Borehole (M12, ranked 3rd), and the Centralia Tunnel (M19, ranked 6) may be sufficient for installation of passive treatment. However, because of the proximity of the Locust Gap Tunnel and many other discharges to streams, roads, or railroads, and the limited availability or access to land at the discharge location, passive treatment would not be suitable at many AMD sites. The reduction of infiltration and removal of culm waste and (or) the relocation of the discharge to nearby areas could decrease the AMD quantities and facilitate treatment at some of the priority AMD sites.

Table of Contents

     Purpose and Scope
     Physiography and Land Use
     Geology and Mining History
     Water Quality
     Water-Quality Protection and Restoration
Methods of Water-Quality Site Selection, Sampling, and Analysis
Effects of Abandoned Mine Drainage in the Mahanoy Creek Basin
     Flow and Quality of Streams
     Streamflow Variability
     Contaminant Concentrations and Loads
     Aquatic Ecology
     Streambed Chemistry
Characterization and Remediation of Abandoned Mine Drainage
     Characteristics of Abandoned Mine Drainage Sources
     Remedial Priorities and Alternatives
     Data Usage and Limitations
References Cited

This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.

View the full report in PDF 2.0 MB

For more information about USGS activities in Pennsylvania contact:
USGS Pennsylvania Water Science Center
215 Limekiln Road
New Cumberland, Pennsylvania 17070
Telephone: (717) 730-6960
Fax: (717) 730-6997
or access the USGS Water Resources of Pennsylvania home page at:

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