BALTIMORE, MD (September 16, 2004) – A new test of MTBE levels in the tank field at Upper Crossroads Exxon suggests that actions by the Maryland Department of the Environment (MDE) and ExxonMobil have begun to reduce groundwater contamination by the gasoline additive.
The most recent test result reported to MDE by ExxonMobil showed MTBE at 1.2 parts per billion (ppb). The action level for MTBE (methyl tertiary butyl ether) in Maryland is 20 ppb.
“This is good news, but it does not mean the problem has been solved or that the department’s scrutiny of the situation will decrease,” said Kendl P. Philbrick, the secretary of the environment. “We will continue to monitor the water supply in the Upper Crossroads and oversee the cleanup until the contaminant is below the action level.”
Philbrick also said that emergency regulations ordered by Governor Robert L. Ehrlich, Jr. were nearing completion and could be in place before the end of the year. “We have the ability to keep this pollutant out of our drinking water and are going to do so,” he said. The new regulations would emphasize vapor leaks, suspected as a source of the groundwater contamination in Fallston.
The new test, which was performed in late August, was done on the same well where ExxonMobil reported a reading of 26,000 ppb in March.
On June 18, 2004, ExxonMobil installed a soil vapor extraction system on the tank field monitoring pipe and one groundwater monitoring well to remove MTBE vapors from the soil around the station. By early July, MTBE levels had dropped to 97 ppb.
Other wells near the service station show a downward trend in MTBE levels. Monitoring well #2, which is located about 10 feet from the tank field, has shown a decline in MTBE levels from a high of 3,700 ppb to 1,700 ppb MTBE. Other monitoring wells around the station have shown a general downward trend or no change.
MTBE was first added to gasoline in the 1970s to replace lead. Because it makes gasoline burn more completely and thus with fewer emissions, the Environmental Protection Agency (EPA) requires MTBE or another additive in gasoline sold in parts of central Maryland as well as in many other states.
EPA tests have shown the compound to be potentially carcinogenic when inhaled in high concentrations. While no connection has been made between MTBE and disease, Maryland has set its action level at 20 ppb, where the compound can be tasted and/or smelled.
On August 11, 2004, Governor Robert L. Ehrlich, Jr. announced that MDE would issue emergency regulations to prevent MTBE and other petroleum products from reaching groundwater supplies. The regulations will require, among other things, more frequent testing for vapor as well as liquid leaks and rigorous safeguards against leaks.
Tests for leaks at the station, which is located at the intersection of Route 152 and Route 165 in Harford County were conducted by ExxonMobil in July 2004. The tests revealed more than 30 potential vapor leaks in fittings and connections, all of which were repaired.
Philbrick said that ExxonMobil is continuing its subsurface investigation to determine the extent of contamination from the station. The results of the investigation will be made public in October. A corrective action plan is due by the end of the year. MDE continues to work with ExxonMobil, local government, and the residents of Upper Crossroads to investigate and ultimately remediate the MTBE contamination to ensure that drinking water supplies are clean and safe. Additional site information can be found on MDE’s web site at mde.maryland.gov.
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