In 1955, the US Air Force laid a strip of concrete 15,000 feet long (nearly 2.5 miles), 300 feet wide, and 19 inches thick, adjacent to a dry lake bed in the Mojave Desert of Southern California. This strip of concrete (designated 04R/22L) was constructed to serve as the main runway for the next 25 years for Edwards Air Force Base, but ended up in service for 53 years. During that time, the 412th Test Wing performed test flights of every aircraft type used by the US military on that strip of concrete and each of the six space shuttles touched its wheels down on 04R/22L.
Over time, hard service in extreme desert conditions aged the runway, causing the concrete to spall and become a foreign object debris hazard. In 2008, 13,000 feet of deteriorating runway were removed and replaced, and massive concrete slabs were stockpiled on more than 45 acres of desert in the South Base area of Edwards.
Over the next 6 years, approximately half of the stockpiled concrete was processed and crushed by the Air Force, as funding and the demand for recycled concrete aggregate allowed. However, state regulatory agencies perceived the concrete slabs as stockpiled waste and pressured the Air Force to be more proactive in management of the material.
Through a competitive procurement in summer 2016, OTIE was awarded a contract through the USACE Los Angeles District (LA District) to process and sort 143,000 tons of commingled material consisting of the runway slabs and other concrete rubble, metal material, and landfill overburden. The contract included optional items to process and crush the remaining massive concrete slabs at South Base. But a multitude of challenges delayed the project schedule by 9 weeks and left OTIE without a heavy construction subcontractor after the first phase of work.
To maximize efficiency and production, OTIE re-engineered the project and retained a heavy construction company with which OTIE has an established and successful history. Confident in OTIE’s approach, the LA District modified OTIE’s contract to process an additional 350,000 tons of stockpiled large concrete slabs and subsequently crush 433,000 tons of processed concrete. The processing and crushing of the remaining concrete material were performed concurrently, saving the Air Force over $600,000.
As with any project, there were minor challenges to overcome in the subsequent phases of the project, but effective collaboration between the field crew, the project management team, and the subcontractor led to the last few tons of concrete being crushed on October 3, 2018—more than 6 months ahead of schedule.
The crushed concrete is intended to be used as cover material or rip-rap at former base landfill Sites 3 and 29 and skeet range Sites 81 and 102 under two additional contract awards to OTIE through USACE Tulsa and LA Districts.
The concrete crushing project at Edwards AFB is the largest concrete recycling project undertaken by the Air Force. Base Civil Engineering estimated that it would have taken the Air Force approximately 30 years to complete the crushing project if they had self-performed the work. OTIE was able to complete the project in just 18 months.