A simulation-management methodology is demonstrated for the rehabilitation of aquifers that have been subjected to chemical contamination. Finite element groundwater flow and contaminant transport simulation are combined with nonlinear optimization. The model is capable of determining well locations plus pumping and injection rates for groundwater quality control. Examples demonstrate linear or nonlinear objective functions subject to linear and nonlinear simulation and water management constraints. Restrictions can be placed on hydraulic heads, stresses, and gradients, in addition to contaminant concentrations and fluxes. These restrictions can be distributed over space and time. Three design strategies are demonstrated for an aquifer that is polluted by a constant contaminant source: they are pumping for contaminant removal, water injection for in-ground dilution, and a pumping, treatment, and injection cycle. A transient model designs either contaminant plume interception or in-ground dilution so that water quality standards are met. The method is not limited to these cases. It is generally applicable to the optimization of many types of distributed parameter systems. This paper is not subject to U.S. copyright. Published in 1984 by the American Geophysical Union.Paper number 3W1963. the three categories of alternatives for remedial action as physical containment, in situ aquifer rehabilitation, and withdrawal followed by treatment and use. Physical containment systems prevent the flow of contaminated groundwater with the aid of engineered features such as slurry trench cutoff walls, grout curtains, and hydrodynamic controls. Aquifer rehabilitation methods may involve injection and recharge systems that are supplemented by above-ground chemical-treatment or may involve injecting a neutralizing or biochemical degradation agent into the contaminated zone. The approach of withdrawal, treatment, and use does not attempt to exploit any assimilative capacity or attenuation properties of the aquifer and simply removes the contaminated water from the system. Chemical treatment processes and waste containment for aquifer decontamination have been discussed by Landon and SylVester [1982], Yaniga [1982] for hydrocarbon contamination, Stover [1982], McBride [1982], and Ohneck and Gardner [1982] for removal of toxic organic chemicals, Osiensky et al. [1982] for uranium tailings disposal problems, and Molsather and Barr [1982], as well as Giddings [1982] for landfill leachate containment. .
Aquifer management research has also treated the problem of groundwater pollution control. Remson and Gorelick [1980]considered the optimal locations of pumping and injection wells and the determination of minimum pumping rates for the hydraulic containment of contaminated groundwater. Their approach was to include the finite difference approximation of the groundwater flow equation as constraints in a linear programing problem. Further constraints served to control hydraulic gradients which prevented the plume from spreading as well as ...