EVALUATING THE EFFICIENCY OF THE MARCHAND ABANDONED MINE TREATMENT FACILITY IN LOWBER, PA

The Marchand treatment facility located in Lowber, Pennsylvania is a passive system designed to remediate coal mine contaminated water from the abandoned Marchand Mine prior to release into Sewickley Creek. The passive system consists of six connected settling ponds followed by a large, constructed wetland. Original evaluation of the site following implementation in 2006 suggested a reduction in dissolved Fe from 74 mg/L at the input to 0.8 mg/L at the outflow but no recent study has documented the efficiency of the system since 2007. Data was collected during fall of 2022, with two days of field work showing similar readings of discharge, dissolved oxygen (DO), pH, and dissolved total Fe content as determined by Hach TNT 858 total Fe test kits using a DR 1900 portable spectrophotometer to evaluate the modern storage potential and efficiency of treatment. The system inflow had an average pH around 6.4, dissolved total Fe of 56 mg/L, and DO of 5.2%. The discharge at the connection between pond 6 and the constructed wetland averaged a pH of 7.5, less than 0.2 mg/L Fe reading (below detection) and DO of 96.8%. In the fall of 2022, the entire system removed Fe at a rate of 11.8 g Fe m^-2 day^-1 with calculations based off the average discharge of 7338 L/min as indicated by a staff gage and previously determined rating curve. Considering the dissolved total Fe content at the entrance to the mine as 56 mg/L and the outflow as below 0.2 mg/L, the Marchand passive treatment system is still an effective system of removing dissolved Fe. Comparison to prior results published in 2008 shows the dissolved total Fe inflow has dropped from 74 mg/L to 56 mg/L and the dissolved total Fe outflow also has dropped from 0.8 mg/L to less than 0.2 mg/L reading (below detection). The modern pH data remain similar in both the inflow and outflow locations to their values in 2008.