WINGFIELD PINES

The Problem: Wingfield Pines discharge is located in Upper St Clair Township in the 80 acre floodplain that the Allegheny Land Trust just acquired. Located at ‘mile 16’, it is the uppermost AMD discharge in Allegheny County. It discharges directly into Chartiers Creek, instead of into any tributary. This was not one of the original eight sites included in this DEP Growing Greener Grant. The Allegheny Land Trust had its own Growing Greener Grant to monitor and design remediation. Monitoring was done by a local conservation group, USC Citizens for Land Stewardship. They agreed to volunteer their data in order to complete our profiling of all of the major AMD discharges to Charters Creek in the lower watershed.  Wingfield Pines has the highest flow of all nine discharges at 1500 gpm. The discharge upwells in a concrete structure located at the base of a surface mine highwall. It is strongly net alkaline for an AMD discharge at 425 mg/L. While the iron content at 14 mg/L is the lowest of the nine, the iron loading, given the flow volume, ranks 4th. Some of the mining appears to have been done in the 1930-40s and one nearby mine was active into the 1970s. Here again speculation about the actual mine structures, contours, and whether tunneling barriers are intact leads to possibilities of sealing, raising a pool and relocating the discharge. The recharge area is estimated to be 1300 acres with a relatively high recharge rate of 1.15 gpm/acre (highest among the other discharges). This could be caused by additional areas being drained to the site, barrier pillars being or not being intact among a couple sets of mines, more infiltration due to less urbanized areas above the mines, or a loss of a stream flow into the mine. Obviously so many scenarios complicate remediation strategies.

The Solution:  A $650,000 grant from the Pennsylvania Department of Environmental Protection (DEP) will support construction of this passive treatment system that will eliminate iron oxide from the abandoned mine drainage that is flowing onto the Wingfield Pines property owned by Allegheny Land Trust in Upper St. Clair and South Fayette Townships. The flow of the iron-laden discharge is at a rate of 2,000 gallons-per-minute. The treatment system is designed so the mine drainage flows freely through a series of pie-shaped shallow ponds and wetlands that will be constructed to capture the iron sediment before it reaches Chartiers Creek. Currently, the mine drainage is impairing the water quality of Chartiers Creek with 43 tons of iron oxide sediment each year. The ponds will capture the sediment that will later be collected and sold for pigment.