Aboveground Storage Tank Failure in Hebron Maine Closes School
Heating oil leaked out of a tank at the Hebron Station School during a scheduled fuel delivery on December 24, 2013. An estimated 1,900 gallons of fuel spilled out of the basement tank on to the floor of the tank room. The accident occurred because of a faulty tank gauge. The driver of the oil delivery truck heard the whistle stop while pumping 160 gallons and after checking the tank gauge, which indicated the tank fuel level was still low, he continued to pump. The fuel then overflowed into a concrete secondary containment that was not sealed. One foot of fuel filled the containment bunker, when the oil delivery driver realized the mistake. His oil company promised to remove the oil the same day. A school custodian checked the room on December 25 and found a dry containment bunker. He assumed it had been pumped out but later discovered the oil had actually leached out of the space. The Maine DEP was then called in to assess the extent of the leak. Maine DEP Oil and Hazardous Materials Responders worked with an environmental team that drilled monitoring wells around the property. After the Maine DEP response team evaluated the data collected, they determined that the oil leached into the sandy soil under the concrete and into nearby wetlands. The accident forced about 135 elementary students to relocate to Oxford Hills Comprehensive High School in South Paris, following winter break. The environmental clean up company tested the school's drinking water well and did not see or smell evidence of oil. As a precaution, the staff and students are using water from the school’s 8000-gallon water tank, which provides water for fire suppression and is adequate for consumption. Air quality monitoring systems will be in place for months to ensure that the air is safe for students to be attending classes. More than 1,700 gallons of oil is still beneath the school's basement tank room, which is on a concrete slab. Pads and booms are absorbing oil that is showing up in the wetlands and storm drains.
How could this accident been avoided?
The time measured from the start of the leak to when it completely drained out of the room was 6 hours. This incident highlights the importance of a properly installed secondary containment system and an overfill alarm. To meet SPCC Compliance rules, concrete containment dikes should be sufficiently impervious, and discharges should not escape until a clean up has occurred. A chemical resistant epoxy coating designed for concrete is ideal for applications like this. Overfill alarms are required by the U.S. EPA to be installed in underground storage tanks but not aboveground tanks. In this scenario, had an overfill alarm been installed, it would have prevented a leak. Veeder-Root overfill alarms are designed to provide both a visual and audible alarm at the fill port for the tank. When connected to a Veeder-Root TLS System that is set to trigger at a preset level, the alarm will provide an early warning of a potential overfill. Regardless of the type of system used to warn the oil delivery driver, the devices should be tested monthly by onsite staff and inspected yearly by a certified tank component installation company.
Information from: Sun-Journal, http://www.sunjournal.com