Impacted Water Supplies
Impacted Municipal
Wells
Tricholorethene (TCE) was first discovered in Cheyenne municipal wells west of town in 1997. It was subsequently found in other wells in the Borie well field, an important source of city water during the summer months. Initially the City of Cheyenne Board of Public Utilities (BOPU) was able to treat the water in an existing radon removal system to below detection for TCE.
However in late 2008, BOPU was forced to turn the pumps off in the Borie well field, because of an increase in TCE contamination in the Finnerty from 20 to 40 parts per billion (ppb). The US Army Corps of Engineers installed a Granular Activated Carbon filtration system on the Finnerty well in July 2009. Water from the Finnerty well coming out of the filtration unit is now below detection for TCE.
City Water is Safe to drink
The City of Cheyenne Board of Public Utilities
(BOPU) adopted a policy prohibiting any detectable amount of TCE in city
drinking water and has achieved this goal.
BOPU will continue to assure that no TCE enters the city water
supply.
Impacted
Residential Wells near the Belvoir Ranch
Two residential wells showing 13 and 28 parts per billion (ppb) TCE, sampled in February 2009, had also been tested in 2005 and 2006. Sampling in 2005/2006 showed residential wells under the 5 ppb TCE level set by US EPA for safe drinking water purposes. When results of groundwater sampling for TCE from a nearby municipal well increased from 20 ppb to 40 ppb a new round of sampling of residential wells was conducted in 2009. Two residential wells that had been below the drinking water standard of 5 ppb TCE were above 5 ppb. Bottled water was immediately provided to the residences. Granular Activated Carbon (GAC) systems to remove TCE from drinking water were installed in June of 2009 on two residential wells that serve six households. The first sampling event took place on July 1, 2009. Water from the residential wells coming out to the GAC filtration systems showed water to be below detection for TCE.
Quarterly sampling over the past six quarters of 13 residential wells continues to show two residential wells above 5 ppb. These two residential wells are still being treated using GAC systems.