BALTIMORE — The Maryland Department of the Environment and Cecil County Health Department are investigating the Sunoco gas station at 355 Telegraph Road in Rising Sun to determine how petroleum-related compounds found in gasoline have been detected in monitoring wells on the property.
A certified letter sent to homes in an area within one-half mile of the the business indicates that there is no evidence that the compounds — benzene and methyl tertiary butyl ether (MTBE) — have left the property. All buildings inside town limits are connected to the Chester Water Authority and would not be impacted, a fact that the town assured residents of on its social media pages Friday.
“Although the Town uses our well system as an emergency back up, the Town does not use this well water as our everyday source. Our water supply comes from Chester water and is in a closed pipe system. As a precaution, the town is monitoring our back up wells for any issues or impacts,” the statement reads.
Those who received the registered letter and have private wells can request that the water be tested, or can have it tested privately. The letter offered a list of 20 companies certified to conduct such testing.
Samples from the three monitoring wells operated by Sunoco were taken Aug. 26 but received by MDE Nov. 4. Those samples showed benzene in ranges from 40.6 to 546 parts per billion. That exceeds the standard tolerance of 5 ppb. Those samples also showed MTBE at 28.6 ppb, which is above the 20 ppb standard.
However, noting the space of time between when the samples were taken and reported, MDE required another set of testing data, which was collected Nov. 6. The three monitoring wells and the well used to supply drinking water to the property were tested. MTBE was detected at acceptable levels but benzene in wells 1 and 3 ranged from 23.9 to 315 ppb.
The gas station and convenience store has had monitoring wells in place since 2005. At that time test results indicated benzene presence as high as 310 ppb while MTBE was found as high as 3,000 ppb.
As those amounts dissipated the case was closed in March 2011. However annual sampling continued to be an annual requirement in keeping with high-risk groundwater use area regulations.
This new investigation opened Nov. 6 will determine if Sunoco has to perform any additional actions to mitigate the situation.