"Date published, May 1991." "Managed by Martin Marietta Energy Systems for the U.S. Department of Energy under contract no. DE-AC05-84OR21400." "ORNL/TM-11866." Includes bibliographical references.

An in-depth analysis of the effectiveness of pumping groundwater for aquifer restoration was conducted based on: (1) performance records for 16 sites where pumping with the objective of aquifer restoration has been implemented for periods of 2 to 12 years, and (2) recent theoretical and modeling studies.^The reduction of aquifer concentrations is the primary indicator of effectiveness of groundwater extraction.^However, other indicators of effectiveness such as plume containment, mass reduction, and achievement of specific cleanup goals were also components of the evaluation.^Based on our review of performance records and recent theoretical studies, the following can be concluded regarding the use of groundwater pumping for aquifer restoration: (1) Pumping is effective for contaminant mass reduction, plume containment and extraction of groundwater for point-of-use treatment.^Its use for attaining these objectives should be encouraged.^(2) Groundwater pumping is ineffective for restoring aquifers to health-based levels.^This reality needs to be explicitly recognized by regulators.^(3) The primary contributors to the ineffectiveness of pumping in meeting cleanup goals are the time-dependent decrease in the rate of desorption of contaminants from contaminated soils and the existence of immobile contaminants either in the non-aqueous phase or trapped in zones of low permeability.^(4) Remedial time frames of 2 years to 30 years were predicted at the sites reviewed.^Regulators currently maintain that 20 to 40 years may be needed to reach health-based cleanup goals.^However, recent modeling studies estimate pump and treat time frames of 100 to 1000 years.^22 refs., 5 figs., 4 tabs.