Effects of Instantaneous and Continuous spill of Radium-226/224 and total uranium loading scenarios for Coles Hill Uranium Mine, Virginia was modeled to evaluate subsequent water quality impact to the Banister River, which feeds into the mouth of Lake Gaston that serves as the main drinking water supply source for Cities of Norfolk, Virginia Beach and vicinities.  Completely Randomized (CR) experimental design technique was employed in analyzing gross gamma exposure rate measurements from the American Nuclear Corporation Uranium Mine and Mill, Wyoming. The verified findings were subsequently applied to evaluate hypothetical natural background post uranium mill operations in Coles Hill, Virginia. Uranium milling processes were then simulated.  A critical scan value (=DCGL_scan) was developed to flag an anomaly of surface contamination during post remediation Final Status Surveys (FSSs). The referenced background is critical for meeting the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) guidance for post remediation FSS (NRC,2000). Sometimes selecting the correct reference area mean (=natural mean) is difficult because of large variances created by subsurface uranium ores. These variances can occur over relatively small distances and the sensitivity of the radiation detection instrumentation plays a large factor in discerning radiological contamination from background. SAS Procedures (Shapiro-Wilk Test, ANOVA, CR) were used to determine the presence of collinearity between the number of samples (=treatment) and the areas (=block). Subsequently, q-hyper distribution was applied to estimate a Class I Land Survey Unit soil sampling density and was compared to the MARSSIM guidance approach.  Radiological Water Quality Modeling was applied to Coles Hill study site under the worst-case catastrophic failure (500-year event) condition simulating the 1969 Hurricane Camille of 27 inches of rain in Nelson County, Virginia. The model showed the impact to the Banister River’s drinking water supplies under instantaneous and continuous spill through two cracked or ruptured 40- acre impoundment’s containment at Coles Hill Uranium Mine study site, Virginia was minimal at most. The water quality impact at drinking water intakes would likely be less than the Virginia’s Drinking Water Standards for gross alpha, Radium-226/224 and total uranium.

KEYWORDS: Radiological Water Quality Modeling; Background Exposure Rate; Q-hyper Function; MARSSIM