CHESTERTOWN, MD (JUNE 13, 2006) – The Maryland Department of the Environment (MDE) continues to find MTBE (methyl tertiary-butyl ether) in recent samples of drinking water in Chestertown. An ongoing investigation of the potential sources of contamination has required the installation of monitoring wells at nearby gas stations.
“Chestertown’s drinking water still currently meets public health standards,” said MDE Secretary Kendl P. Philbrick. “However, since we have noticed a slow increase in trace amounts of MTBE in the drinking water over the past three years, we have worked with the town to develop strategies to protect the supply of drinking water, replace shallow wells with deeper ones, and investigate the cause of contamination.”
Over the past nine months, samples taken from Chestertown’s water treatment plant have indicated an MTBE presence between 13.3 and 15.7 parts per billion (ppb). A recent sample taken from the distribution system on May 2, revealed a spike of 24.6 ppb. This elevated sample exceeded the state’s “action level” of 20 ppb, prompting MDE and Chestertown officials to immediately begin testing each of the Town’s wells. The most recent analysis of the drinking water from a sample collected on June 8, showed MTBE levels at 14.6 ppb.
Town officials are prepared to remove any contaminated wells from the public water system. The Town currently uses five shallow wells and one deep well to supply water to its approximately 6,000 customers. After the water is pumped from each well, it is treated and put into the distribution system as finished water. A sixth shallow well was taken offline last year after testing showed MTBE levels up to 40 ppb. Should Chestertown need to remove further shallow wells from the town’s water system, supply should not be impacted as the town has completed the permitting and construction of a second deep well to be put online in the next several weeks.
“Through ongoing monitoring and analysis, in coordination with MDE, we are making sure that Chestertown’s drinking water is kept safe,” said Town Manager Bill Ingersoll. “Knowing that the shallow aquifer is more sensitive to contamination, we developed a new well in the deeper aquifer. We are prepared to maintain an adequate water supply for the needs of our community. With the addition of our new deep well we can more than replace the production of any well taken off of the system.”
In response to the contamination of one of the Town’s shallow wells in August of 2005, MDE began compelling local gas stations and other area potential contamination sources to install monitoring wells on their sites and perform a subsurface investigation. The initial results of the investigation indicate that high levels of MTBE have been found at several monitoring wells. MDE is following up these findings with an ongoing investigation.
“In addition to monitoring the town’s drinking water, MDE is continuing its rigorous investigation into the cause of the contamination,” said Secretary Philbrick. “It is important that we find the source of MTBE in order to prevent further contamination.”
MTBE is a fuel additive in motor gasoline that raises the oxygen content in order for the gasoline to burn more completely, reducing harmful tailpipe emissions from motor vehicles. MTBE is a colorless liquid that dissolves rather easily and contaminates water. The use of MTBE as a fuel additive is being phased out and replaced with ethanol, throughout the industry.
Because MTBE is not regulated under the federal Safe Drinking Water Act, the U.S. Environmental Protection Agency (EPA) has not set a national standard for MTBE, nor does the agency require MDE to monitor MTBE in public drinking water supplies. EPA continues to study potential health effects and has put it on a list of contaminants for which to consider setting drinking water standards. While federal laws do not require MDE to monitor or sample for MTBE, MDE has done so since 1995 for all community drinking water systems.