TOTAL DISSOLVED SOLIDS IN AN OHIO MINED AREA 1

At a mined area in northeastern Ohio, Total Dissolved Solids (TDS) concentrations within a large creek and its tributary sometimes exceeded the local regulatory limit. The TDS stemmed from active and inactive coal mines and their settling ponds, from which dissolved loads were carried to the creek and tributary via outfalls. The existing compliance strategy was to control the timing of problematic outfalls, reducing flows when exceedance was imminent; however, because of the variability of weather and mining activities, identifying the problematic outfalls would require more frequent measurements than could be performed manually. Data logging stations were deployed on the creek and the tributary between each mining outfall, and specific conductivity (for TDS) and pressure (for flow) were recorded at 10-minute intervals. Field testing resulted in an innovative design for the data logger housing. A telemetry station was installed to provide real-time warnings should TDS-thresholds be exceeded downstream of the coal mine. Data analysis included calculations of mass loading and the annual TDS delivered by each outfall. Results indicated four outfalls whose mass loads were particularly problematic, and that TDS was occasionally resultant from an unknown source located upstream of the coal mines. Recommendations are included regarding the designs of systems.