title: Reducing long-term remedial costs by transport modeling optimization.
abstract: The Department of Defense (DoD) Environmental Security Technology Certification Program and the Environmental Protection Agency sponsored a project to evaluate the benefits and utility of contaminant transport simulation-optimization algorithms against traditional (trial and error) modeling approaches. Three pump-and-treat facilities operated by the DoD were selected for inclusion in the project. Three optimization formulations were developed for each facility and solved independently by three modeling teams (two using simulation-optimization algorithms and one applying trial-and-error methods). The results clearly indicate that simulation-optimization methods are able to search a wider range of well locations and flow rates and identify better solutions than current trial-and-error approaches. The solutions found were 5% to 50% better than those obtained using trial-and-error (measured using optimal objective function values), with an average improvement of approximately 20%. This translated into potential savings ranging from 600,000 dollars to 10,000,000 dollars for the three sites. In nearly all cases, the cost savings easily outweighed the costs of the optimization. To reduce computational requirements, in some cases the simulation-optimization groups applied multiple mathematical algorithms, solved a series of modified subproblems, and/or fit "meta-models" such as neural networks or regression models to replace time-consuming simulation models in the optimization algorithm. The optimal solutions did not account for the uncertainties inherent in the modeling process. This project illustrates that transport simulation-optimization techniques are practical for real problems. However, applying the techniques in an efficient manner requires expertise and should involve iterative modification to the formulations based on interim results.
authors.affiliation: US Army Corps of Engineers, Hazardous, Toxic, and Radioactive Waste Center of Expertise, 12565 W. Center Road, Omaha, NE 68144-3869, USA. dave.j.becker@usace.army.mil
authors.forename: David
authors.initials: D
authors.lastname: Becker
authors.forename: Barbara
authors.initials: B
authors.lastname: Minsker
authors.forename: Robert
authors.initials: R
authors.lastname: Greenwald
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Karla
authors.initials: K
authors.lastname: Harre
authors.forename: Kathleen
authors.initials: K
authors.lastname: Yager
authors.forename: Chunmiao
authors.initials: C
authors.lastname: Zheng
authors.forename: Richard
authors.initials: R
authors.lastname: Peralta
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003365:Costs and Cost Analysis; D052918:Environmental Restoration and Remediation / Q000191:economics* / Q000379:methods* / Q000639:trends; D008962:Models, Theoretical; D013997:Time Factors; D014186:Transportation / Q000191:economics*