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Surface-water and groundwater interactions in an extensively mined watershed, upper Schuylkill River, Pennsylvania, USA

Hydrological Processes

By:
, , , , and
DOI: 10.1002/hyp.9885

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Abstract

Streams crossing underground coal mines may lose flow, while abandoned mine drainage (AMD) restores flow downstream. During 2005-12, discharge from the Pine Knot Mine Tunnel, the largest AMD source in the upper Schuylkill River Basin, had near-neutral pH and elevated concentrations of iron, manganese, and sulfate. Discharge from the tunnel responded rapidly to recharge but exhibited a prolonged recession compared to nearby streams, consistent with rapid infiltration and slow release of groundwater from the mine. Downstream of the AMD, dissolved iron was attenuated by oxidation and precipitation while dissolved CO2 degassed and pH increased. During high-flow conditions, the AMD and downstream waters exhibited decreased pH, iron, and sulfate with increased acidity that were modeled by mixing net-alkaline AMD with recharge or runoff having low ionic strength and low pH. Attenuation of dissolved iron within the river was least effective during high-flow conditions because of decreased transport time coupled with inhibitory effects of low pH on oxidation kinetics.


A numerical model of groundwater flow was calibrated using groundwater levels in the Pine Knot Mine and discharge data for the Pine Knot Mine Tunnel and the West Branch Schuylkill River during a snowmelt event in January 2012. Although the calibrated model indicated substantial recharge to the mine complex took place away from streams, simulation of rapid changes in mine pool level and tunnel discharge during a high flow event in May 2012 required a source of direct recharge to the Pine Knot Mine. Such recharge produced small changes in mine pool level and rapid changes in tunnel flow rate because of extensive unsaturated storage capacity and high transmissivity within the mine complex. Thus, elimination of stream leakage could have a small effect on the annual discharge from the tunnel, but a large effect on peak discharge and associated water quality in streams.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Surface-water and groundwater interactions in an extensively mined watershed, upper Schuylkill River, Pennsylvania, USA
Series title:
Hydrological Processes
DOI:
10.1002/hyp.9885
Volume
28
Issue:
10
Year Published:
2014
Language:
English
Publisher:
Wiley
Contributing office(s):
Pennsylvania Water Science Center
Description:
28 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Hydrological Processes
First page:
3574
Last page:
3601
Number of Pages:
28
Country:
United States
State:
Pennsylvania
Other Geospatial:
Schuylkill River