A large acid discharge emerges from the abandoned Gibson-Halstock surface mine in the Little Laurel Run watershed. As part of our work on Little Laurel, we have built a passive treatment system on this discharge. Pre-treatment data indicates an average chemistry of pH 3.4, iron 2.6 mg/L, aluminum 3.9 mg/L and 56 mg/L acidity at a flow rate averaging 110 gal/min. This amounts to a load of 2 lb/day of iron, 4.8 lb/day of aluminum and 62 lb/day of acidity.
An EPA 319 grant of $43,098 was received for design in February 2011. Alder Run Engineering designed a treatment system consisting of a settling pond followed by 2 flushable limestone beds and then 2 final settling ponds.
An EPA 319 grant for $535,733 was received in June 2013 for construction of the system. The project was bid in mid-2014, but start was held up because of endangered Indiana bats and by difficulties with obtaining landowner agreement from Bender Coal Co.. Later, Bender traded their land at the site with the PA Game Commission so that all of the treatment systems would be on Game Commission land, though more than two years was required to attain full agreement. Construction was started during early 2015 and was essentially completed in fall 2016.
Monitoring to date shows the outflow to be strongly net alkaline with low metals.
This project, along with the smaller Old Beldin Project across the valley, will clean up mine drainage contaminants in the lower half of Little Laurel Run, leading to recovery of fish and other biota.