PORTLAND, Ore. – The U.S. Army Corps of Engineers will rehabilitate one of Green Peter Dam’s two spillway gates September 2014 through February 2015, improving the dam’s ability to help reduce flood damage to South Santiam River communities.
The project includes strengthening the gate face; replacing the gate’s arms, trunnion pins and wire ropes; and replacing or refurbishing electrical controls, gearboxes and other systems. The rehabilitation work is similar to that performed on the spillway gates at Foster Dam about 7 miles downriver in 2008-2009.
A public closure of the entire area from Quartzville Road on the north bank to the private property fence/gate on the south bank, including the North Viewpoint and Billings Park, will go into effect when construction crews begin moving to the site Sept. 15.
The road over the dam will be reduced to one 12-foot wide lane Sept. 15-30, and then closed entirely Oct. 1 to Nov. 30 except for emergencies. One 12-foot wide lane will also be available Dec. 1 until the project concludes in mid-February.
“We understand the impact of this project – particularly the area and road closures – on the local community and reservoir users, but our highest priority is ensuring Green Peter Dam’s ability to reduce flood damage in downstream communities,” said Brian Schmidtke, project manager for the spillway gate rehabilitation.
With a total capacity of 428,000 acre feet, Green Peter is third only to Lookout Point and Detroit dams in its ability to store Willamette Basin flood water. The dam prevented the South Santiam River from rising eight additional feet at the Waterloo gauge during the January 2012 storm event, and is estimated to have prevented over $17 million in damage to downriver communities during the 2011-2012 flood season.
Construction crews will pin the spillway gate face in place to hold back water, but Corps reservoir regulators will aggressively manage the reservoir’s elevation to keep the gate unwatered as much as possible. This may result in higher flows for longer durations downstream following significant rain events. As always, the Corps’ goal is to keep the river below flood stage.
For more information about the Corps’ Willamette Valley flood risk management mission and spillway gate rehabilitation program, visit http://www.nwp.usace.army.mil/Missions/Water/Floods.aspx.