Concrete environmental benefits, cost savings found in Brightwater construction material

Brightwater pipeline facilities will be "greener" - and a little less costly - thanks to a decision to replace cement with a waste-to-resource material called fly ash to make concrete.

The contractor on Brightwater's east tunnel, Kenny/Shea/Traylor JV, expects to save about 5 million pounds of cement by using a fly ash concrete mix to build two 80-foot-deep tunnel access shafts at the North Creek portal site in Bothell. The shafts are part of the 13-mile pipeline being built to carry wastewater to and from the new Brightwater treatment plant when it comes online in 2010.

Concrete made from fly ash, a glass-like powdery waste material from coal-fired electric plants, has been used on major construction projects since the 1930s, including Hoover Dam.

Using fly ash in concrete not only keeps millions of tons of waste out of landfills, but it also reduces demand for cement production, which is considered to be the largest single source of carbon dioxide, or "greenhouse gas" emissions worldwide.

"We've put a priority on protecting the environment and creating resources from the wastewater we treat, so it's very exciting that Kenny/Shea/Traylor is helping us extend our mission to how we build our facilities," said King County Executive Ron Sims.

"Replacing cement with fly ash is a win for everyone," said Ted Budd, vice president of Kenny Construction's tunnel division. "It's a high quality material that's better for the environment, and it's even a little less expensive."

Fly ash concrete generally costs slightly less than cement, though market conditions have driven up its cost over the past few years.

Still, the substitution of flyash for a portion of the cement saves about half a penny per pound, or about $25,000. The county and its contractors will continue to explore opportunities to use fly ash concrete for other Brightwater structures, including buildings on the treatment plant site.

People enjoy clean water and a healthy environment because of King County's wastewater treatment program. The county's Wastewater Treatment Division protects public health and water quality by serving 17 cities, 17 local sewer utilities and more than 1.4 million residents in King, Snohomish and Pierce counties. Formerly called Metro, the regional clean-water agency now operated by King County has been preventing water pollution for more than 40 years.