Groundwater Treatment Systems
 
Nature and Extent of Contamination
 
Previous and current environmental tests have been conducted at and around the Redfield site, and have involved drilling soil borings on the property and in the neighborhoods, installing groundwater monitoring wells, and the analysis of subsurface soil, groundwater and soil gas samples. This data from these tests help scientists determine how far the affected groundwater has traveled away from the site.
 
Map Of Groundwater Flow Direction
 
Groundwater Containment System
 
In March 2000, a groundwater containment (or pump and treat) system began operating. The system is intended to prevent solvents in groundwater from flowing away from the Redfield site and into the neighborhoods. The system operates continuously with occasional shutdowns for periodic maintenance or system repairs. The system will recapture solvents that bypass the wells during short shut-down periods.
 
The pump and treat system works like this — a hydraulic barrier was created by installing 8 groundwater pumping wells about 25 feet from the fence line. These wells capture contaminated water under the site before it flows into the neighborhoods. Groundwater, a short distance beyond the fence line, also is captured and cleaned by the system.
 
The captured water is pumped from the ground to the surface where it is then treated to remove the solvents. Clean water is then either returned to the ground or surface water, through a permitted process. Both of these discharges are conducted under permit authority from the US Environmental Protection Agency and the Water Quality Control Division of the Colorado Department of Public Health and Environment. The quality of the treated water is evaluated weekly in accordance with the discharge permit.
 
By preventing groundwater from leaving the site, solvents from the Redfield site will no longer flow into the neighborhoods. The system will also prevent the Colorado Department of Transportation's solvents, which have flowed onto the Redfield property, from entering the neighborhoods. The remaining portion of the plume in the neighborhoods will be flushed by clean water around the plume. Solvents in the groundwater below the neighborhoods will dissipate over a period of many years. Eventually, the venting systems in individual homes no longer will be necessary.
 
 
Treatment System Monitoring
 
Monitoring of the groundwater containment system consists of analyzing samples of incoming water and treated outgoing water from the system. Incoming groundwater samples are collected periodically to assess the concentrations of chemicals. Treated water samples are collected weekly to confirm chemicals are removed from the water.
 
Containment System Monitoring
 
Hydraulic barriers prevent the flow of groundwater from the site or from the containment area. If groundwater cannot pass through the barrier, then chemical solvents that are dissolved within the groundwater cannot pass through either. Groundwater monitoring is conducted quarterly at the site.
 
Initial Remediation Results
 
Results for each treated water sample collected during the period confirm there were no chemicals present in the treated water above the discharge standards. The treatment system has successfully removed chemical solvents from the water and permit requirements were not exceeded.
 
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