The Pine Run Watershed Association with administrative support from The Jefferson Conservation District received a Growing Greener Grant to assess non-point source pollution (NPS) on the 303 (d) listed Pine Run Watershed (tributary of Mahoning Creek). Through this assessment the primary NPS pollution was determined to be from abandon mine drainage (AMD). All discharges and tributaries entering Pine Run have been prioritized according to daily loadings of water quality parameters associated with AMD. The Pine Run Watershed Implementation Plan was completed in 2006. This implementation plan is being used to schedule remediation activities.

     The Corbettown discharge was determined to be the largest producer of iron in the entire Pine Run Watershed. This discharge accounts for 94% of the iron, 15% of the acid, 52% of the manganese, 10% of the aluminum, and 35% of the sulfate entering Pine Run from the eleven major base flow sources. The Corbettown discharge contributes a near 100% increase in total flow at the point of confluence with Pine Run. The flow increases from 1,789 GPM, upstream from the point of confluence, to 3,327 GPM, downstream from the point of confluence.

The goal of this project was to cost-effectively reduce the negative affects of the Corbettown AMD discharge on the Pine Run watershed. To achieve this goal, a passive AMD treatment system has been constructed.
 
     The treatment system configuration is designed to fit within constraints of the site. The Corbettown discharge site has unique physical characteristics that limit the available area to construct the passive treatment system. As such, a simple design to allow the discharge to be aerated via a sluiceway and maximized settling area was utilized. The system consists of a collection box, by-pass pipes, sluiceway, pond, pond partitions, discharge pipe, and energy dissipater. Water exiting the pond flows under railroad tracks by way of a large livestock/access tunnel, travels under the road by way of the existing pipe, and enters Pine Run via an existing stream channel which has been stabilized with R-4 sandstone.
 
     The discharge was collected in a Y-shaped box constructed of treated lumber. The collection box allows for water to either enter the sluiceway or be passed around the system via a 12 inch PVC bypass pipe exiting on the energy dissipater. The bypass pipe was installed first to allow the discharge to be temporarily re-routed during construction of the system. Once construction was complete, the bypass pipe was left to allow for re-routing the discharge during maintenance events.

     Exiting the collection box, the discharge enters an HDPE lined collection channel. The channel is a trapezoidal channel 4 feet wide at the top and covered with R-4 sandstone. The channel serves two purposes. The channel is the first opportunity for the oxidation of the ferric iron, and the rock lining provides surface area to begin collection of the iron precipitate. In addition, the channel conveys the discharge from the collection box to the top of the elevated sluiceway. The sluiceway is 10’ x 20’ and is water depth averages 1 foot. An 83 ft. channel was dug with 5 feet of fall from beginning to end and lined with HDPE liner. Twelve concrete barriers were placed on alternating angles against the flow. The area was lined with R-4 sandstone. The sluiceway enters in the northeast corner of the settling pond (Figure 6). The settling pond is 102 ft. x 230 ft. and lined with an HDPE liner.

     The pond has an engineered retention time of 12 hours. Pond partitions were installed to increase retention of suspended solids by channeling water over a greater distance. This allows more time for suspended solids to settle. The channel that conveys the discharge to Pine Run was loaded with iron sludge and showed signs of severe erosion. In order to correct this erosion problem and provide additional settling of iron, the channel was lined with R-4 stone. Complete removal of the discharge would remove approximately 637 pounds of iron per day (116 tons per year). The removal of this iron will, in time, as scouring takes place on stream substrate, provide habitat and suitable water quality to macroinvertebrate communities and fish populations downstream of the discharge. Approximately 2.5 miles of the stream will be restored and over 6 miles of stream will be improved. An incalculable portion of Mahoning Creek will also benefit from this project, as Pine Run will enter with improved water quality and biological habitat.