South Transfer Station

Seattle, Washington
Rainwater Harvesting
Owner:
Seattle Public Utilities
Engineer:
URS Corp, Inc.
Contractor:
M.A. Mortenson Construction, KLB Construction
Technical Description:
      • DuroMaxx® rainwater harvesting cistern        
Installation:
February 2011

Seattle Public Utilities (SPU) built a new $50 million waste transfer station in South Seattle. The two-story, 140,500 square foot building with 84 parking spots replace the old South transfer station located across the street.

“The new facility will allow the city to maintain reliable solid waste services in an economical and environmentally sound manner,” said Henry Friedman, project manager for SPU.

SPU’s goal was to build this project to the standards of the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) certification program and to achieve LEED Gold status. The LEED rating system measures a proposal’s impact on the environment through various categories such as climate change (carbon emissions), indoor air quality, resource depletion, human health, water efficiency and habitat alteration, among others.

To achieve credit for water efficiency, SPU wanted to harvest rainwater to reuse onsite. The harvested water will be used for irrigation, to wash the transfer station floor, as washdown water for the tipping floor. and for the wheel wash which trucks can utilize as they leave the tipping floor. With limited available space on the site, they needed to utilize an underground system.

SPU worked with URS Corp Inc. to find a rainwater harvesting cistern to meet their needs and chose a DuroMaxx Steel Reinforced Polyethylene (SRPE) cistern from Contech Engineered Solutions. The system is comprised of two 84” diameter cistern sections that are each 75 feet long. The DuroMaxx SRPE cistern was chosen because it was available in such a large diameter and provided water tight joints using welded couplers. It was also an economical solution.

The cistern features include a 12” rain leader for runoff collection, valve control outlets to drain the tanks for maintenance, four 36” access risers with integral ladders, and internal pumps connected to the irrigation system. The irrigation will be used for the new landscaping around the facility, including 123 on-site trees, 32,000 square feet of ground cover, and 81,000 square feet of grass cover. The system was installed below grade by KLB Construction and was backfilled in just three days.

“The installation went smoothly and we preferred to utilize the DuroMaxx product over the alternatives,” said Aiesh Ragih with KLB Construction.

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