Date implemented:
September 2001

Final remediation design:
A system of 12 nested injectors was installed in the source area. Semi-permanent injectors manufactured using 1-inch PVC screen and riser were installed to allow the controlled injection of permanganate reagent directly into the area of contamination. Each injector was installed with a sand pack to just above the screen, and grouted to the surface. Upon setting of the grout, a charge of permanganate was pressure injected into each injector. A 10% (by weight) solution of permanganate was introduced into each injector, with as much volume as each injector would take, to a maximum of 100 gallons. The injectors were then connected to each other in ranks, and to a head tank by PVC piping. The gravity feeding to all of the injectors on a continuous basis was then started. Up to 300 gallons per day of 1-2% solution were fed into the system during remediation. Most of the injectors were completely above the water table to avoid drainage of reagent directly into groundwater without extensive soil contact. To control PCE that was mobilized into groundwater from the soil source area, a line of injectors was installed dowm stream. These injectors were operated at very low volumes and controlled based on the results of a monitoring well immediate downgradient.

Results to date:
In the source area, PCE concentration started at 1,900 µg/L. One month into the remediation process, PCE concentration had dropped to 926 µg/L and contunue to decrease further to 284 µg/L three monthe after initiation of the remedy. Post-remediation PCE concentration, monitored 8 months later, was found to be 48 µg/L. Downgradient PCE concentrations decreased from 40 µg/L to 15 µg/L within a year.

Next Steps:
In February 2003, the State of Colorado issued a No Action Determination Approval, stating that the property could be used for commercial purposes, and did not pose an unacceptable risk to human health and the environment.