Environmental Background
A natural gas company contracted with AGES to close a 6,000-gallon diesel underground storage tank (UST) at an operations center located in Beaver County, Pennsylvania. The UST was formerly used for fueling company support vehicles. An associated dispenser island with two (2) pumps was located adjacent to the UST.
UST Closure
To begin the closure, AGES excavated the top centerline of the UST. No pitting, corrosion, or any holes were noted in the tank. All piping encountered during excavation was removed. The tank was then removed from the excavation and placed on plastic adjacent to the excavation. The tank atmosphere was monitored for explosive limits and oxygen levels using an O2/LEL meter. No explosive vapors were present in the UST. After monitoring the tank atmosphere, AGES personnel cut a hole in the side of the tank with a pneumatic chisel, and then cleaned and vacuumed the tank interior. Residual liquid from the UST were removed with a drum vacuum and the inside of the tank was scraped clean of residual sludge. AGES then completed the demolition and removal of the pump island and dispensers.
Confirmatory soil samples were collected during field work from beneath the UST and from directly below the pump island. A small amount of water was encountered in the tank cavity; therefore, one water sample was collected from the tank cavity. Results for all of the soil samples and the water sample were less than applicable PADEP standards/action levels for UST closure, as presented in PADEP Closure Requirements for Underground Storage Tank Systems.
A closure report was prepared to document site conditions and no further work was required by the PADEP to address this area.
Special Project Features
All project work was completed to comply with applicable PADEP standards.
