Abinash Agrawal/ contributed
It’s likely that the fuel has reached the water table and may seep into the Great Miami River, said Abinash Agrawal, an earth and environmental sciences professor and water remediation expert at Wright State University. It’s also likely that the fuel created toxic vapors that can migrate into nearby buildings, he said.
“Given the close proximity, the groundwater is likely moving from the diesel site toward the Great Miami River, and it is carrying some dissolved fuel as a contaminant,” he said. “Dissolved fuel contaminants are not expected to biodegrade within that short travel.”
Some of the fuel did seep into the groundwater, said Dayton Water Director Mike Powell, noting that the city sent an environmental scientist to the site when they learned about the leak. The city and the Ohio EPA determined that the fuel leak is not a threat to Dayton’s drinking water because none of its well fields are near the facility.
RTA officials discovered the leak on Aug. 25, according to the Ohio EPA, which issued a notice of violation for the incident this February. An Automatic Tank Gauging, one of the most-common forms of leak detection devices, alerted RTA officials, said Brian Bohnert, public information officer for the Ohio Department of Commerce.
Immediately after officials learned about the leak, the transit agency informed the Ohio EPA, BUSTR, the Dayton Fire Department and the city’s water department, RTA Deputy CEO Bob Ruzinsky said.
A total of 16 monitoring wells and three recovery wells ― some of which were installed as a result of previous incidents ― are on the site to recover fuel that reached the ground water, the Ohio EPA and Bohnert said. As of January, one recovery well and three monitoring wells are still indicating measurable amounts of petroleum on the site, he said.
The leaked fuel likely will accumulate as a separate oil pool in the aquifer, Agrawal said. That’s because diesel and other petroleum hydrocarbons are lighter than water, and they tend to float on the water table.
The silver lining for the environment is that the oil pool will remain in the area and not travel far, further evidence that the city’s drinking water will not be impacted. The pool will slowly dissolve in the groundwater over the next five to 10 years, Agrawal said. But diesel fuel is also volatile, which creates a plume of toxic vapors that usually migrates and enters nearby buildings through the basement, he said, and requires air quality monitoring.
It’s common for fuel to contaminate soil. But the risk of vapor migration beyond 1,500 feet of the fuel source is low, Agrawal said.
The RTA is responsible for investigating all potential avenues of exposure, according to BUSTR’s rules, to ensure there is no threat to human health and the environment, Bohnert said.
The RTA did not respond to emails asking if it’s been monitoring the vapor plume of if they know where it is in the area.
BUSTR does not intend to fine the RTA for the incident at this time, Bohnert said. However, if the agency fails in the future to properly maintain its underground storage tank systems or fails to complete clean-up activities, BUSTR may pursue a fine as part of the enforcement process, he said.
The cleanup process is ongoing, Bohnert said.
“Because every site is unique and every case has its own set of variables, it is difficult to estimate when an investigation will be completed,” Bohnert said. “Investigation and remediation at the site will continue under our rules until we obtain enough data to conclude the release is not a threat to the environment or human health.”