DISCRIMINATION OF SEASONAL FLOW AND CONTAMINANT VARIANCE IN A 2ND ORDER SPRING USED FOR PUBLIC WATER SUPPLY, ANNISTON, ALABAMA

Coldwater Spring is a deep-sourced, 2^nd order spring of low variability with a mean annual flow volume of 31 million gallons per day located at the toe of Coldwater Mountain in Calhoun County, Alabama within the fold and thrust belt of the Valley and Ridge Province. The spring is the public water source for the nearby cities of Oxford and Anniston, Alabama. The spring has been impacted by the migration of volatile organic compounds in groundwater sourced from Anniston Army Depot, located approximately 1.7 miles to the north. The primary organic contaminant detected in spring water is trichloroethene (TCE). Water samples have been collected from Coldwater Spring on a monthly schedule for 12 years thus providing sufficient data to determine the TCE concentration trend. Current average TCE concentration in spring water samples is above the US Environmental Protection Agency maximum contaminant level for drinking water of 5 µg/L. A correlation technique using data shifting of spring flow volume, rainfall, and TCE concentration data sets combined with calculation of nonparametric correlation statistics allows evaluation of 1) seasonal rainfall to spring flow volume variance and 2) spring flow volume to TCE concentration variance. The technique discriminates a strong relationship among the three variables during seasonal intervals of more stable flow as indicated by higher correlation coefficients during these periods.