Abandoned
mine drainage (AMD) is a significant problem in areas with a history
of coal mining. Clean surface water infiltrates into abandoned
underground mine systems and is contaminated via interaction with
pyrite, yielding sulfuric acid. The acidified water
subsequently discharges into rivers downstream. The Schuylkill River
Watershed of central Pennsylvania contains economically important
anthracite deposits which have been mined since the 1800s in the
headwaters of the Schuylkill River. The subsurface is rife with
abandoned coal mine tunnels, few of which are marked or mapped. AMD
is a major concern for both people and wildlife in the Schuylkill
River Watershed. Streams throughout this watershed lose water
through highly permeable areas of the streambeds. That water
seeps into coal mine tunnels and becomes contaminated. Resistivity
surveys along stream channels can be used to identify such seepage
points. These seeps are recognizable as low resistivity
anomalies where significant volumes of water infiltrate to become
contaminated in the subsurface mine pools. This study includes 44
resistivity profiles that measure a total of ~1800m (6000ft)
of stream channel near Heckscherville, PA from July 2009 and 30
resistivity profiles that measure ~2300m (7600ft) of stream channel
west of Heckschersville, PA from May and June of 2011. All profiles
were performed using a dipole-dipole array with an electrode spacing
of 5m or less. Flow measurements were analyzed and compared to
resistivity anomalies to confirm possible locations of high
permeability in the stream channel. The results of these
surveys are used to focus remediation efforts in the headwaters of
the Schuylkill Watershed. Stream channel reconstruction or chemical
grouting was conducted in 3 locations from the results of the
2009. Remediation of target locations discovered through the
2011 geophysical surveys is yet to ensue.
