At this site, near Big Mine Run, treated and untreated mine drainage waters
merge. The untreated water (far side of creek with orange sediments) flows from
an abandoned coal mine. The treated water, flowing from an outfall not visible
in the foreground, has been pumped out of the active Girard Estates coal mine.
Students measured the pH of both waters. The untreated mine waters had pH values
ranging from 3 - 4, whereas the pH of the treated water had been raised to neutral
values of about 7, much less acidic than rain water.
The confluence of these waters mixes to create a zone with pH's of about 5.5,
where aluminum hydroxide (whitish yellow) is precipitating in a band along the
middle of the creek, whereas lower pH's on far side of creek result only in
Fe hydroxide precipitation.
More info about Acid Mine Drainage and Remediation is available from the Penn. DEP and the Shamokin Creek Restoration Alliance.