The 40-plus-year-old Dykstra and Galli levees along the west bank of the Green River in northeast Auburn are showing their age.

After heavy flooding in the winter of 2006, King County inspectors found damage to both levees, including slumps, sinkholes, oversteep banks and scour, or erosion of stream bed material along the bank and at the base of the levees.

Those levees matter to many people because they protect from high waters the adjacent neighborhoods of multi- and single-family homes, as well as streets and other public infrastructure and commercial development on Auburn Way North. Their wear puts people who live and work within that area at risk in the event of a flood.

Starting July 1, a partnership between the King County Flood Control District and the U.S. Army Corps of Engineers will make the repairs to 650 feet at the downstream end of the Dykstra levee and 1,100 feet of the Galli levee. The project, scheduled for completion by Nov. 1, 2008, will accomplish the following:

• Re-grade the existing bank to a stable slope angle

• Reestablish protection to the levee toe and to the bank

• Incorporate two layers of willows and dogwoods above toe rock and re-vegetate the upper slope with native shrubs and

• Install anchored large wood along the levee toe in select locations.

“Right now, those levees are protecting that neighborhood from flooding and the houses immediately adjacent to that from erosion under the buildings,” said engineer Deborah Scheibner, King County’s manager for the Dykstra and Galli levee projects. “If that continues to happen, they will be impacted. On several occasions, homeowners have told us they saw water within a foot of the top of the bank.”

The King County Flood Control Zone District was established in April of 2007 to reduce risks from flood and channel migration hazards, avoid or minimize environmental impacts of flood hazard management and reduce the long-term cost of flood hazard management.

The King County Council in November of 2007 approved a property tax increase, directing some $10.6 million annually to more than 25 miles of levies along the Green River, including the Galli and Dykstra levees.

The Federal Emergency Management Agency (FEMA) has said all the levees must be fixed or thousands of property owners might face high flood insurance premiums and restrictions on building that would essentially halt construction.

Work on the Galli and Dykstra levees will be done between 7 a.m. and 5 p.m., Mondays to Fridays. All access will rely on public rights of way, temporary construction easements, existing flood protection and Washington Department of Natural Resources easements.

Residents should expect truck traffic on haul routes, noise and vibration, relocation of some fencing, benches, removal of trees and vegetation, detour of pedestrian access and temporary fencing around each construction site.

“People will still be able to use the top of bank there when this is done, but 15 feet of it will need to be clear for access to do operation and maintenance,” Scheibner said.

New fencing will be installed after the project, and the Army Corps of Engineers will revegetate the upper banks in early spring of 2009.