OPTIMAL GROUNDWATER REMEDIATION METHODS APPLIED TO A SUPERFUND SITE -FROM FORMULATION TO IMPLEMENTATION

A hydraulic control optimization model is applied to the conceptual an d implementation analysis of a ground-water remediation system in coas tal New Jersey. The site is modeled using a distributed parameter fini te-difference model containing 36,000 nodes within five layers. The co nceptual problem is to determine the feasibility of producing a captur e zone which encompasses the entire existing plume while recharging al l extracted water within property boundaries in such a way that the re charged water satisfies criteria on its fate. The conceptual analysis problem is formulated as a linear program in which the total extractio n pumping is minimized, and requirements are placed on hydraulic heads and gradients in both horizontal and vertical directions. A requireme nt is also made that all extracted water be recharged to the subsurfac e. The model is used for determination of the feasibility of the remed iation concept. Details of constructing constraints for a large-scale formulation are presented. The concept of constraint calibration, usin g particle tracking to insure that constraints are producing desired r esults, is introduced and demonstrated. The optimization formulation i s used for detailed implementation analysis of the remediation system. A number of techniques for modifying elements of the conceptual model results, such as unrealistically small pump rates, are described. The optimization approach is found to be useful for determining the feasi bility of the remedial strategy at this site and for producing results which can be used as a starting point for detailed analysis of the re mediation strategy.