| Contents Notes |
" methodology is described that will allow the pollution potential of any hydrogeologic setting to be systematically evaluated anywhere in the United States. The system has two major portions: the designation of mappable units, termed hydrogeologic settings, and the superposition of a relative rating system called DRASTIC. Hydrogeologic settings form the basis of the system and incorporate the' major hydrogeologic factors which affect and control ground-water movement including depth to water, net recharge, aquifer media, soil media, topography, impact of the vadose zone media and hydraulic conductivity of the aquifer. These factors, which form the acronym DRASTIC, are incorporated into a relative ranking scheme that uses a combination of weights and ratings to produce a numerical value called the DRASTIC Index. Hydrogeologic settings are combined with DRASTIC Indexes to create units which can be graphically displayed on a map. The application of the system to 10 hydrogeologically variable counties resulted in maps with symbols and colors which illustrate areas of groundwater contamination vulnerability. The system optimizes the use of existing data to rank areas with respect to pollution potential to help direct investigations and resource expenditures and to prioritize protection, monitoring and clean-up efforts. The full report was submitted in partial fulfillment of Contract No. CR-810715-01 by the National Water Well Association under sponsorship of the U.S. Environmental Protection Agency. This report covers a period from October 1983 to March 1987, and work was completed as of April 1987. " |
