Levi’s Stadium, home of the San Francisco 49ers, made environmental history when it first opened in 2014. In addition to using recycled and reclaimed materials for construction, sporting a 27,000-square-foot green roof, and generating solar power, the $1.2 billion stadium has an elaborate system for stormwater management. Details about this novel system were recently made public.
Since rainwater can turn a football field into a muddy swamp, it can easily turn a parking lot into a floodplain, stormwater collection and treatment system company Oldcastle Building Solutions points out in their new case study of Levi’s Stadium. The stadium in Santa Clara, designed by HNTB, is 1.85 million square feet, has a capacity of 68,500 (not including club seats and luxury suites), and approximately 30,000 parking spots. All those hard surfaces can generate enormous stormwater runoff.
Adding to the challenge, the San Tomas Aquino Creek flows right by the stadium and ultimately feeds the ecologically-sensitive Guadalupe Slough as well as San Francisco Bay. As Oldcastle Building Solutions points out, the stadium site sits on land that has a high water table with storm drain lines close to the surface.
To deal with stormwater in the parking lots, project engineers GHD installed a modular system of precast concrete biofiltration units. They have cells containing mulch, biofiltration media, and drainage rock. The biofiltration media drain 5 to 10 inches per hour to be in line with the county’s requirements. Above ground the system resembles normal landscaping, but it allows the water to flow downward, get treated, and then go into an underground pipe. Microbes break down the filtered pollutants while the water irrigates plants and trees nearby.
Altogether, the stadium has six biofiltration systems in parking lots and areas right next to the building. One of the main systems is 2.5 feet wide and slightly over 600 feet long. Oldcastle Building Solutions reported that the project team installed more than 2,500 lineal feet of bioretention cells for approximately 14,000 square feet of space onsite.
The biofiltration is self-sustaining for the most part, according to the company, and protects the surrounding areas from contaminated runoff. Officially opening on July 17, 2014, Levi’s Stadium was on schedule and on budget. It was the first stadium hosting an NFL team to receive LEED Gold certification.