BIOGEOCHEMICAL ASSESSMENT OF ABANDONED MINE DISCHARGES ON WICONISCO CREEK, SCHUYLKILL AND DAUPHIN COUNTIES, PENNSYLVANIA

The purpose of this study was to investigate the impact of three abandoned coal mine drainages on water quality in Wiconisco Creek. Abandoned coal mine drainages (AMD) from Porter Tunnel, Big Lick Tunnel, and Short Mountain Mine all empty into Wiconisco Creek, a 43 mile tributary of the Susquehanna River, that has historically been called “black creek” by locals due to excessive coal sludge in the stream. Each AMD input is different, requiring a different treatment system. Discharge from the Porter Tunnel is low in both pH and alkalinity and high in metals (especially iron and aluminum), requiring treatment with both limestone and settling ponds. Discharge from Big Lick Tunnel is high in dissolved iron and low in dissolved oxygen, requiring a serious of vertical drops to aerate the water and precipitate iron. AMD from Short Mountain Mine is also high in metals and low in dissolved oxygen requiring a series of 3 settling ponds to remove the iron. For this study, samples were collected both upstream and downstream of each treatment system and in Wiconisco Creek above and below the confluences of the treated waters with the creek. Conductivity, pH, dissolved oxygen, and temperature were measured in situ using a Hach HD40 meter with probes. Large volume samples were collected, transported to the lab, filtered, and alkalinity and acidity immediately determined. Later analyses on preserved samples included ion chromatography (IC) for simple cations and anions and inductively coupled plasma – optical emission spectroscopy (ICP-OES) for 11 selected metals. Sediments collected from both Porter Tunnel and Big Lick Tunnel were analyzed using scanning electron microscopy (SEM).

Alkalinity and pH at Porter Tunnel (0 mg/L as CaCO₃ and 3.62, respectively) were low compared to Big Lick (7.04 and 100 mg/L) and Short Mountain Mine (6.58 and 21.0 mg/L). Conductivity at Porter Tunnel (843 µS/cm) was higher than at Big Lick (283 µS/cm) or Short Mountain Mine (174.9 µS/cm). Higher levels of sodium, chloride, magnesium, and calcium in Porter Tunnel AMD indicate possible road salt contributions. Diatoms Pinnularia sp. and Eutonia sp. Were present in the Porter Tunnel sediments. Big Lick Tunnel sediments contained no diatoms, rather Gallionella sp., an iron-precipitating bacterium commonly found in near neutral AMD.