Original Date: 09/14/1998
Revision Date: 01/18/2007
Best Practice : Extraction and Recharge Concept for Remediation
The disposal practices of the 1950s created a contaminated groundwater plume in the northwest section of Raytheon Missile Systems Company’s (RMSC’s) facility. The plume is located 500 feet below the ground surface, and covers a 65-acre area. To clean this contaminated groundwater, RMSC uses a pump-and-treat remediation system. In addition, the company implemented a recharge field at this site to contain the groundwater and stop its northward migration (500 feet per year). The reclamation well field consists of 21 upper zone extraction wells, four lower zone extraction wells, nine shallow groundwater zone extraction wells, and 32 recharge wells.
The pump-and-treat remediation system works in conjunction with the recharge well field to re-inject groundwater back into the aquifer after contaminants are removed (Figure 2-7). This technology significantly increased the remediation rate of the groundwater in the aquifer beneath the plant. In addition, RMSC reduced its expected completion time for groundwater cleanup from 50 to 15 years, and removed more than 20,000 pounds of contaminants from over 16.8 billion gallons of groundwater over an 11-year period.
The extraction and recharge concept for remediation provides many advantages for RMSC. Among the benefits are containment of the groundwater plume; an increased rate at which groundwater moves within the aquifer toward the extraction wells; a flow rate that is not restricted by the use of groundwater after it is cleaned; and a flushing effect within the subsurface which expedites contaminant removal whenever the water table rises around the recharge wells. In addition, the company effectively doubled the gradient of water at the extraction wells by mounding the water from recharge wells.
Figure 2-7. Aquifer Cross-sectional View
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