Two‐Stage Ground‐Water Remediation Design

Although available technology may be inadequate for the complete remediation of certain contaminated ground water‐sites, hydraulic control can be used to reduce the extent of, and contain, ground‐water contaminants until adequate technology can be developed. The design of such a remediation system can be viewed as a two‐stage process. A first stage is the achievement of a reduction of the extent of the contaminant, and a second stage is the maintenance of the contaminant at this reduced areal extent. Viewed in this light, alternative pump staging criteria can be considered within the design process. These criteria can include allowing the well location and pumping rate to change during the remediation effort. This paper analyzes the economic significance of incorporating increasing complexity of pump‐stage criteria into the design process. The analysis is conducted using numerical simulation and a new multistage optimization formulation. The analysis concludes that while different pumping strategies should be used in each stage of remediation, it is generally unnecessary to consider the impact of the pumping strategy in the first stage on the remediation cost in the second stage.