King County, Corps of Engineers to rebuild damaged levee

Improvements will protect Kent and hundreds of millions in investments

King County and the U.S. Army Corps of Engineers are teaming up today to repair portions of a Green River levee that protects an estimated $650 million of commercial development in the Green River Valley.

High river levels caused significant damage to the Briscoe School Levee, which runs along the eastern shore of the Green River as the stream flows through Kent and into Tukwila.

King County Water and Land Resources Division flood patrols noticed a set of parallel cracks running for about 400-feet across the top of the levee, plus a 100-foot-long slump along the lower slope on the river side of the levee.

These signs of damage occurred after several days of high flows in the Green River from rainfall and snowmelt in early 2006. Once the floodwaters receded, engineers analyzed the damage and determined that the deep-seated slump would likely continue to worsen, compromising the integrity of the flood-protection structure.

"Repairing the Briscoe School Levee is one of our highest priority projects for the year," said Mark Isaacson, director of the King County Water and Land Resources Division. "Without these repairs, it's possible that high flows in the Green River this fall or winter could do even more damage to what is already a dangerously weakened levee."

"One of the lessons we learned from Hurricane Katrina is that we must invest in and protect critical infrastructure," said King County Executive Ron Sims. "By doing this important work now and with a partner, we make better use of our regional resources."

Levee reconstruction will include:

• Using large rocks to rebuild the "toe," which sits in the water and forms the base or buttress of the levee
• Setting the levee back with flatter side slopes to create a more stable structure
• Placing fish-friendly logs with root wads in the water to improve wildlife habitat and provide additional protection for the levee.

A U.S. Army Corps of Engineers economic evaluation for the project said the properties protected by this levee extend at least two miles east of the right bank and  2-1/2 miles north (downstream) of the work area. This commercial area of more than five square miles contains about 500 light manufacturing, warehouses and distribution facilities.

"Working together with levee sponsors and owners to repair damages from the 2006 floods is a top priority of the Seattle District, U.S. Army Corps of Engineers. Public safety comes first in all our missions," said Col. Michael McCormick, commander. 

The levee also protects numerous roads that provide transportation access between Auburn, Kent, and Renton, and utilities that supply gas and electricity to the many businesses.

The total cost to repair the damaged levee is estimated to be $834,000. King County will provide $369,000 in funding for the repair work; the Army Corps of Engineers will contribute $465,000 toward the total cost.

The levee reconstruction project is one of the top priorities identified by the recently formed King County Flood Control Zone District. This district was formed earlier this year to help address the backlog in maintenance and repairs to the county's levees and other flood-prevention structures. The King County Council will consider a funding recommendation for the district this fall.

More information on flood hazard management planning in King County is available at www.metrokc.gov/dnrp/wlr/flood/flood-control-zone-district/.