SANDSTONE SPRINGS AS CONTRIBUTORS TO KARST AQUIFERS IN THE VALLEY AND RIDGE PROVINCE

Most of the research conducted on the hydrogeology of the Valley and Ridge Province (V&R) has focused on the carbonate rock aquifers commonly found in the valleys and at the base of the mountains. However, springs sourced from the clastic shale and sandstone rock units (“sandstone springs”), also play an essential role in creating headwater streams, recharging the carbonate aquifers, and sustaining regional base flows. The high quality water chemistry of sandstone springs makes them valued water sources in the V&R. The springs included in this study are or have been used by four public water districts and two bottled water companies. The majority if these springs are located on the mountain flanks within synclinal or anticlinal structures and discharge water from fractured clastic bedrock or at a sandstone-shale contact. The springs create small streams along the mountain slopes that enter the karst aquifer through swallets at the clastic-limestone contact in the valley below.

Multiple springs in central PA and southeastern WV have been identified and the water chemistry determined. Chemical analyses include pH, temperature, conductivity, dissolved oxygen, major ions, DIC, alkalinity, carbon isotopes, strontium isotopes, oxygen isotopes and contamination indicators (E. Coli and total coliforms using the Colilert® system). Onset Hobo® data loggers were placed in selected springs to monitor temperature. Generally, the springs are perennial with a decreased flow in late summer/early fall. In contrast to karst springs, the sandstone springs flow from a less-soluble matrix and have potentially shorter flow times resulting in water with a lower pH and alkalinity, fewer dissolved ions, and a lower DIC. The total coliform in the water varies significantly based on the rainfall with higher numbers after a precipitation event and lower coliform numbers during dry periods. Temperature data recorded in these springs between April 2017 and July 2017 show a variety of results, some springs are closely tied to storm events and others are not. The sandstone springs in southeastern WV flow from the Martinsburg (Reedsville) Formation and have slightly higher pHs and ion concentrations then do the other sandstone springs due to the presence of carbonate layers and clays in the shale.