EFFECTS OF COMPLIANCE BOUNDARY LOCATION ON CONTAMINANT DETECTION NETWORKS IN AQUIFERS

Groundwater monitoring networks were derived for 15 alternative compli ance boundaries, located from 10 to 150 meters downgradient of a landf ill. For each compliance boundary, a mass transport model was used to define the linear monitoring transect, perpendicular to groundwater fl ow, requiring the fewest detection wells. The distance (d(t)) to the o ptimal monitoring transect was consistently 0.40 to 0.75 times the dis tance to the compliance boundary (d(c)). Compliance boundaries located near a landfill provide capability for early detection, but also requ ire a substantial number of closely spaced wells. As d(c) increases, t he minimum number of wells (N-o) required along the optimal transect d ecreases. However, the rate of decrease (N-o/d(c)) is progressively sm aller in the downgradient direction And there is a value for d(c), in this example 70 meters, beyond which the decrease in N-o is negligible .