Environmental responsibility takes top priority for the airforce reserve station at the Pittsburgh International Airport fuel facility. Thousands of gallons of jet fuel are stored and pumped each year, posing a significant environmental threat if the fuel was to reach ground water levels. In an effort to minimize storm water damage and environmental impact, engineers designed a detention pond which serves as the collection area for the facility’s storm water as well as for potential contaminated runoff or spills.
Normally, the detention pond slopes consist of a series of poured concrete slabs, but over time water works its way underneath the slabs, eroding the subgrade. The underscour of the subgrade robs the slabs of needed support, and they begin cracking under their own weight. This cracking diminishes the detention pond’s ability to withstand erosion, leaving the structure open for containment problems.
“The detention pond area was located in an area of unconsolidated random fill that would cause cracking of the concrete slabs and fail,” explains Gary Austerman of Burns & McDowell, consulting engineer for the Army Corps of Engineers. “The soil requirements necessitated a stable material for the side slopes and bottom that would allow some settlement without failure.”