Remedial Action Assessment for Hazardous Waste Sites Via Numerical Simulation

Abstract

A common remedial action at many hazardous waste sites consists of some type of hydraulic control which generally takes the form of one or a combination of the following: (1) drains, (2) wells and (3) permeability barriers such as walls and caps. All of these hydraulic controls have been tested in construction projects where workers need dry conditions. Under these circumstances, time frames are relatively short (a few years or less) and monitoring is very accurate (workers identifying leaks within days). For hazardous waste sites, however, design criteria for hydraulic controls must consider time frames of many years and monitoring systems that include only a few observation points. Because the design criteria for construction projects and remediation are so different, there is no assurance that hydraulic controls will work equally well for both applications. For hazardous waste sites, uncertainty in the effectiveness of hydraulic controls has led to the combined use of modelling and monitoring. This usage of modelling in assessing various remedial actions is demonstrated by presenting simulation results from four hazardous waste sites. Groundwater flow modelling is used to evaluate various combinations of drains, walls and caps at the Lipari site in New Jersey. A variably-saturated flow model is applied to various combinations of a wall, cap and drains considered for the Love Canal site in Niagara Falls, NY. A flow and transport model is applied to a purge well system to recover a chlorinated hydrocarbon spill in New England. Finally, an immiscible flow model is applied to the S-Area site, also in Niagara Falls, to evaluate the remedial action necessary to prevent the downward movement of dense non-aqueous liquid. In all four applications, emphasis is placed on the groundwater system response to the remedial action. The results of such simulations may be used in an iterative fashion to improve both remedial design and monitoring.

Keywords

Ground water hazardous waste numerical simulation remedial actions chlorinated hydrocarbons Lipari NJ Love Canal Niagara Falls NY U.S.A.

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References

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