GroMoPo Metadata for Pekin (IL) municipal model

A technique based on numerical ground-water flow modeling and unconstrained nonlinear optimization has been developed to provide guidance for protecting municipal ground-water supplies from contamination through capture zone management. The technique involves conventional finite-difference ground-water flow modeling and numerical flowpath/travel time calculation coupled with nonlinear mathematical programming. The objective of the technique is to specify pumping rates for wells in a wellfield such that the configuration of capture zones in relation to existing potential sources of contamination minimizes the risk of contamination while maintaining the required total water output from the wellfield. An important feature of the technique is its ability to incorporate realistic boundary conditions, complicated aquifer configurations, and spatially varying aquifer properties to whatever degree site-specific data are available. Also, the technique is implemented on a personal computer. This approach to ground-water supply protection enhances conventional wellhead protection area delineation because a greater level of protection can be achieved if potential contaminant sources are not even included in capture zones, rather than attempting to reduce the threat of those sources. The effectiveness of the technique was verified through application to a hypothetical ground-water system. Practical aspects were demonstrated with an application in Pekin, Illinois. These efforts demonstrate the utility of an innovative modeling technique in ground-water quality protection.