Tank Closure and Assessment at Airport

This project involved the closure of a 12,000-gallon double-walled underground storage tank (UST) that previously stored jet fuel. Located near a private hangar on the east side of an airport in Lakeland, FL, the tank was out-of-service at the start of the project. The closure process was conducted to ensure environmental safety and in accordance with Florida Department of Environmental Protection (FDEP), federal and local regulations.

The first phase of the project included a thorough closure assessment of the 12,000-gallon UST, identified as Tank #2 in the FDEP STCM database, to ensure there were no leaks or potential for leaks. The assessment also covered the associated remote fill port, dispenser box, and product piping run. Borings were advanced on all sides of the UST, atop the UST adjacent to each spill containment component, adjacent to the dispenser box, the remote fill port, and the associated product piping. The top of the tank was encountered at approximately 4 feet below land surface (bls). Borings were completed using a core drill and stainless-steel hand auger to collect soil samples adjacent to each closed component. Soils were collected at 2-foot intervals for organic vapor analysis (OVA) screening. Elevated OVA readings were encountered from 2 to 4 feet bls at the two boring locations. Groundwater was encountered, necessitating the collection of groundwater samples.

Laboratory soil samples were collected and analyzed for benzene, toluene, ethylbenzene, total xylenes, and methyl tert-butyl ether (BTEX+MTBE) via EPA Method 8260, polycyclic aromatic hydrocarbons (PAHs) via EPA Method 8270, and total recoverable hydrocarbons (TRPH) using the FL-PRO Method. Laboratory results reported concentrations of all contaminants of concern below their respective Soil Cleanup Target Levels (SCTLs) in all samples collected. Following the soil borings, AET personnel installed four temporary monitoring wells, one on each side of the UST. These wells were constructed of SCH 40 PVC with a 0.010-inch factory slotted well screen.

AET performed all field sampling activities, ensuring the closure process was conducted efficiently and in accordance with all regulatory requirements. The final closure was documented in a comprehensive Closure Assessment Report submitted for regulatory review, ensuring full compliance with FDEP standards.

The tank was filled with EQ #328, an FDEP-approved foam, to fill any voids and prevent future contamination, thereby stabilizing the tank for closure. All associated components, including the Submersible Turbine Pump (STP) sump, product lines, vent lines, and spill bucket, were capped off, with sumps and spill bucket filled with concrete to ensure a secure closure.
The disconnection and removal of Tank #2’s electrical wiring from the circuit breaker panel to the aboveground UST equipment were completed. Additionally, other aboveground equipment, such as one pumping cabinet with hose reels, one fuel/water separator tank, and a 5ft by 6.5ft raised concrete pad, were demolished and removed.

Following the removal and closure activities, the area was backfilled, and a new concrete slab was laid to restore the site to a level grade, ensuring it was left in a safe and stable condition.