Estimating an appropriate sampling frequency for monitoring ground water well contamination

Nearly 1,500 ground water wells at the Savannah River Site (SRS) are sampled quarterly to monitor contamination by radionuclides and other hazardous constituents from nearby waste sites. Some 10,000 water samples were collected in 1993 at a laboratory analysis cost of $10,000,000. No widely accepted statistical method has been developed, to date, for estimating a technically defensible ground water sampling frequency consistent and compliant with federal regulations. Such a method is presented here based on the concept of statistical independence among successively measured contaminant concentrations in time.