The Orange County Health Care Agency and the California Regional Water Quality Control Board required the closure of five underground storage tanks (USTs) at the former Marine Corps Air Station El Toro in Irvine, Calif. Constructed in 1953, these five USTs held 591,426 gallons of jet propulsion fuel and needed to be decommissioned by filling the tanks with an inert solid material in order to achieve regulatory closure concurrence.

Each of these USTs measured 88 feet wide and 13 feet high. Due to their size and their unique placement underground, the Marine Corps Air Station El Toro needed a solution that would be strong enough to reinforce the ground above while providing little to no additional environmental impact.

To add to an already challenging job, there were only 10 days before the cutoff date to finish the project to avoid interruption to the breeding season of threatened species California Gnat Catcher.

Cell-Crete’s specialized Engineered Fill team rose to the challenge and finished installation in just six days. This enabled the contractor, Rore, Inc., to finish grading and hydroseeding the area without incurring liquidated damages.

“We chose Cell-Crete because they are the only installer of cellular concrete that could complete the job to the incredibly tight schedule — notably, their ability to produce more than 3,000 cubic yards of low-density cellular concrete per day,” said Steve Siefert of Rore, Inc. “Because of their seamless installation in six days, we had the opportunity to complete our responsibilities on schedule.”

Cell-Crete used cellular concrete — a material composed of water, cement, and preformed foam — to fill the tanks. It’s blended onsite with portable batch plants. Cell-Crete introduced the foam into the concrete slurry with an in-line blending system to produce air-filled cellular concrete. Once mixed with the concrete, the preformed foam creates a uniform matrix of air voids that are stable enough to withstand the hydration period. This technique leaves behind tiny pore spaces that are evenly dispersed within the concrete.

Cell-Crete set up two portable batch plants onsite to expedite the tank-filling process. These portable batch plants make for easy installation, a highly flowable texture, and impressive compressive strength. It also complies with the strict environmental standards set by the Orange County Health Care Agency.

“Using preformed foam reduced the amount of trucks needed onsite. We produced roughly 120 cubic yards of material with each truck load of cement (27 tons) — traditional [controlled low-strength material] or dirt would have required nine times the truck loads to achieve the same volume,” said Diego Villegas, Engineered Fill Division manager of Cell-Crete.

With the tanks safely decommissioned, the city will turn the site into the Orange County Great Park.

Information provided by Cell-Crete Corporation (