WOODVILLE & MC LAUGHLIN RUN (BRIDGEVILLE MINE)

The Problem: Woodville discharges from a higher elevation than nearby Scrubgrass and tumbles 40 feet down an embankment above the railroad. In the dormant season this brown cone is easily seen from the ChemTech office building’s parking lot that is across the old back channel as it rejoins the new main channel of Chartiers Creek. The discharge is piped under the railroad to the back channel and adds a distinct stain at the confluence with the main channel. Since the discharge is over 40 feet above grade, it is estimated that there was enough “head” (water pressure) to carry the discharge that far. The flow upwells from a thick iron deposit and is the smallest volume at 120 gpm. It also has high iron content, but with low flow accounts for a small iron loading. Flow is measured from a flume that was installed about 20 down from the upwelling. 

The Bridgeville Mine (McLaughlin Run) discharge is located in Bridgeville at about 3 miles southwest (upstream) of the Woodville discharge. It comes in an 18” pipe running under McLaughlin Run Road and a roadside business and empties into McLaughlin Run creek, which continues degraded for a 1 mile run to the back channel. Flow was measured with a timed-tub-fill. At 230 gpm, the flow ranks 6th. It ranks 2nd in aluminum and has moderate acidity. It is 6th in iron loading and 4th with iron content. Because of the network of mines under and nearby, there are several speculations about the source of drainage and where the drainage is pooling. Some of these mines may be leaking into each other from miles around, such as from Bethel Park and Mt Lebanon. Barriers between them may or may not be functioning. Without further investigation, the recharge area is estimated to be 1700 acres with an average inflow of .13 gpm/acre. It may be possible to seal this discharge and redirect it to the south toward, but not necessarily to, Wingfield Pines. This, in addition to what so far has been discussed, would tend to underscore that many of these discharges may be related due to topography, mine network and mine elevations. It also underscores the need for continuing comprehensive and systematic investigation of the mines in these sub-watersheds.

The Solution: The Woodville site was studied by senior engineering students of the University of Pittsburgh in Fall of 2002. They proposed remediation by passively piping the discharge along the railroad for 1.7 miles to the mouth of McLaughlin Run on the back channel, where both the McLaughlin and Woodville could be passively treated on a small floodplain. Both Woodville and Bridgeville Mine (McLaughlin Run) discharges are medium priority because both discharges are highly visible and opportunities exist for reasonably cost-effective treatment. 

SCRUBGRASS 

The first passive remediation project was initiated at Scrubgrass in 1995 by the Scott Conservancy and Scott Township and monitored by an environmental studies program at Chartiers Valley High School. This site can be visited by the public and found a short distance off Scrubgrass Road from the intersection of Bower Hill/Woodville Road near the historical St Luke’s Church. 

The Problem: The remediation project features ponds, active aeration system to speed oxidation and settling and wetland vegetation. However remediation is not complete and the remaining 0.2 mile of Scrubgrass Run is degraded, especially since the discharge accounts for practically all of the flow in the summer and most of the year. 

The upper part of the creek functions more as stormwater runoff. The normal flow could be disappearing into the mines. The discharge at Scrubgrass is net alkaline, relatively low flow and consequent iron loading, but rel7401ative iron content is high enough and the site is accessible enough that Hedin Environmental begin to pilot an iron recovery process. Flow is measured with a weir. 

Located in Scott Township both Scrubgrass and Woodville discharges share the same hill and mines, are 1,200 feet apart, have similar chemistry, and are 1 mile upstream on the main channel from Hope Hollow. The mines that drain both discharges are several and have a combined recharge of about 4,400 acres and an average recharge flow of about .07 gpm/acre. Drainage originates at 1010 feet and drain at about 830. Again mining occurred in the early 1900’s. There may be a couple small pools at the sites. 

The Solution:  It may be possible to seal one of these discharges and direct drainage to one or the other or to a remote site. Mine maps are not detailed enough to make any assumptions without further investigation. However since it is probable that much of Scrubgrass Run, as an active creek, is disappearing into the mines that feed these discharges, it may be possible to seal the creek and restore its normal flow. This could decrease the discharges and result in less pollutants entering Chartiers Creek.

Despite improvements the Scrubgrass system continues to only remove 40-50% of the iron.  This is because the calculated pond/wetland size to treat water is 1.5 acres, but the size of the system ois only half an acre. The Scrubgrass discharge is a medium priority because of existing investment in the system, educational use of the system, and the potential to make the system more effective through cost-effective measures.