The False Positive Problem and The Prevalence of Methane and Solutes in Shallow Ground Water Consumed in Pennsylvania,

1. The False Positive Problem and The Prevalence of Methane and Solutes in Shallow Ground Water Consumed in Pennsylvania, West Virginia, and Ohio D.I. Siegel, Earth Sciences, Syracuse University, Syracuse, New York; B. Smith, EnvirocleanPS, Yukon, Oklahoma; M. Hollingsworth, Chesapeake Energy Corporation, Oklahoma City, Oklahoma; E. Perry, R. Bothun, AECOM, Boston, Massachusetts; C. Whisman, R. Wardrop, D. Good, Groundwater & Environmental Services,, Altoona, Pennsylvania Methane and Solutes in Flowback Occur naturally in shallow aquifers. Proper Forensic Evaluation of Potential Contamination Geochemical Consistency (Na, Cl, Br all must be elevated) Trace metals and Na Alone Equivocal Trace Metal False Positives Caused by Pumping and Unfiltered Samples (Fe, Mn, As) False Positives—Naturally High Concentrations of Substances Assumed to be From Contamination Solution Problem Methane Solutes In NEPA, 24% with dissolved methane; 3.4% exceeded the PADEP regulatory level (7 mg/L); In Western Area, 36% with methane; 3.6% exceeded the Ohio limit of 10 mg/L Solutes Commonly Exceed MCLs or SMCLs. Why? 8.000 samples 13,040 samples HydrochemicalEvolution Leads to High Concentrations of TDS, Na, Cl, Ba and Sr No Relationship CH4 to Nearby Gas Wells NE Western Valleys and Slopes Na-Cl-SO4 Valleys and Slopes Na-Cl-HCO 3 ? Ridge Tops Ca-HCO3 Ridge Tops Ca-HCO3 Sulfide Oxidation Sulfide Oxidation Carbonate Dissolution Slopes Na-HCO3 Slopes Na-HCO3 Carbonate Dissolution Brines Brines Osborne et al., 2011) Ion Exchange Ion Exchange