On October 25, 1994, EPA initiated the Removal Action and began supplying bottled water to 25 residents. A Treatibility Study was conducted by ERT to determine the best method of removing the CCl4, which ranges from 6 to 85,000 ppb. Four air strippers and 29 carbon filters were installed on 33 homes. Surface and downhole geophysics were conducted by ERT, and TAT arranged for an aerial photo and survey of the area. Quarterly monitoring of the contaminant plume and monthly monitoring of the systems is being conducted. Ten monitoring wells were installed, a soil gas survey was completed, septic tanks were sampled and a step test was conducted.
A five-day pump test was conducted on one monitoring well to determine aquifer characteristics. Data from this was used to monitor the aquifer. A preliminary design of a source removal system was presented to Jefferson County Planning and Zoning (and other) officials. Four more observation wells and one more pumping well were installed during June and July of 1996, and one test infiltration well provided information on disposal of treated water.
The CCl4 plume continues to decrease -- probably because of the home treatment units. One carbon filter system has treated about 200,000 gallons of water with about 60 ppb CCl4 with no "breakthrough" detected.
B. Next Steps
Complete the design of source removal and submit it to Jeffco. Schedule/attend Jeffco Public Hearings. Begin construction. Continue to monitor CCl4plume.