The Site is in a residential area called Aspen Park, which is located near Conifer, Colorado, in the foothills of the Rocky Mountains.
In October of 1994 EPA found Carbon Tetrachloride (CCl4) at levels as high as 99,000 parts per billion (ppb) in residential wells.
1. Current Situation
On October 25, 1994, EPA initiated the Removal Action and began supplying bottled water to 33 residents. A Treatability Study was conducted by EPA’s Emergency Response Team (ERT) to determine the best method of removing the CCl4, which ranged from 6 to 99,000 ppb. Four air strippers and 29 carbon filters were installed on 33 homes. A thorough investigation was conducted by EPA Contractors (TAT and REAC) in 1995 and 1996. A source removal system was installed in March of 1997; it consists of 4 pumping wells, 6 reinfiltration wells, an air system, and carbon polishing tanks.
One residential carbon filter system has treated about 546,000 gallons of water with levels of 60 ppb CCl4 with no "breakthrough" detected. Five (5) residential homes remain contaminated with CCl4 at levels between 100 and 1000 micrograms per liter (µg/l) and 17 others remain above the maximum contaminant level (MCL). The highest CCl4 level is 1700 µg/l in one of the pumping wells.
The source removal system has treated 4,400,000 gallons of water, which is reinjected downgradient.
2. Next Steps
Continue monitoring the removal system and the affected homes.