Testing by the N.H. Department of Environmental Services revealed that two gasoline additives could contaminate a major source of drinking water in Dover within the next two years.  

City Manager Mike Joyal confirmed last week that high levels of MtBE (methyl tert-butyl ether) and TBA (tert-butyl alcohol) have been leaking from Madbury Metals and making their way toward the Griffin Well, located off Mast Road between Routes 108 and 155 on the Madbury town line.

The DES told city officials the chemicals would not reach the well for another two years, but advised them to begin planning now. Joyal said the city is working with engineers to determine what types of technology can be used to prevent contamination and what treatment techniques can be used to make sure contaminants are removed from the water.

“The important point is that our drinking supply has not been negatively affected by the contaminants that are migrating from the Madbury Metals site,” Joyal said.

The city is looking for additional water supplies to meet the city’s growing needs. The Griffin Well is capable of supplying the city with a million gallons of drinking water per day, but Joyal said other wells could cover the capacity if the Griffin water is jeopardized.

MtBE is a volatile, flammable and colorless liquid chemical compound that is relatively soluble in water. Low levels of MtBE have been used in gasoline since 1979 as a way to increase the octane rating in fuel and help reduce tailpipe emissions in pre-1984 motor vehicles. In more modern vehicles, the emissions reduction has proved negligible.

Since 1992, MtBE has been used at higher concentrations in some gasoline to fulfill the oxygenate requirements of the Clean Air Act, but since 1999, manufacturers have started to fade out the MtBE because of groundwater contamination.