tailieunhanh - DRASTIC: A STANDARDIZED SYSTEM TO EVALUATE GROUND WATER POLLUTION POTENTIAL USING HYDROGEOLOGIC SETTINGS

At the global level, the relationship between population and environ- mental impact is not easy to test in a way that leads to reliable and non- spurious estimates. This is because of the lack of data on environmental degradation covering a sufficiently large number of countries over a suffi- ciently large period of time. It is for this reason that studies have tended to focus on CO2 emissions and energy use, for which cross-country and time- series data are available. The time dimension is necessary in order to avoid the problem of one-period cross-sectional regressions, which are likely to lead to spurious results if population size or growth. | DRASTIC A STANDARDIZED SYSTEM TO EVALUATE GROUND WATER POLLUTION POTENTIAL USING HYDROGEOLOGIC SETTINGS Linda Aller Jay H. Lehr and Rebecca Petty National Water Well Association Worthington Ohio 43085 Truman Bennett Bennett and Williams Inc. Columbus Ohio 43229 DRASTIC is a methodology which allows the pollution potential of any area to be systematically evaluated anywhere in the United States. The system optimizes the use of existing data and has two major portions the designation of mappable units termed hydrogeologic settings and the superposition of a relative ranking system called DRASTIC. Hydrogeologic settings incorporate the major hydrogeologic factors which are used to infer the potential for contaminants to enter ground water. These factors form the acronym DRASTIC and Include depth to water net recharge aquifer media soil media topography Impact of the vadose zone and hydraulic conductivity of the aquifer. The relative ranking scheme uses a combination of weights and ratings to produce a numerical value called the DRASTIC Index which helps prioritize areas with respect to pollution potential. Introduction National reliance on ground water has increased dramatically over the past twenty years. Concomitant with our reliance on ground water has come the need to protect our ground water resources from contamination. Although contamination due to man has occured for centuries only in the past few years has the nation become aware of the dangers of ground water contamination and of the many ways in which ground water can become contaminated. The potential for ground water contamination to occur is affected by the physical characteristics of the area the chemical nature of the pollutant the rate frequency and the method of application. This paper presents a standardized system which incorporates physical characteristics of any area into a methodology 38 which can be used to evaluate the ground water pollution potential of any hydrogeologic setting in the United