WALLA WALLA, Wash. – Portions of the paved trail on the north side of the federally managed section of the Mill Creek Levee System will be temporarily closed to visitors starting Tuesday, Nov. 17, to accommodate levee-maintenance activities, U.S. Army Corps of Engineers officials announced today.
Workers with heavy equipment and vehicles will be removing overgrown vegetation which has encroached into the levee’s maintenance zone. Work on the north levee will begin at the western-most boundary, near the office parking lot. Initially, the metal division works pedestrian bridge crossing Mill Creek will be closed, but the wooden bridge near Rooks Park will remain open. As work progresses upstream, pedestrian bridge access will switch – the division works bridge will be open, and the wooden bridge will be closed. The paved trail connecting the north levee trail to the Rooks Park parking lot and the entire lot will be closed to visitors throughout the work period to accommodate large-vehicle access to the levee.
Construction fencing and signs will be placed to alert visitors to the closure and encourage public safety. Visitors are encouraged to use the south levee trail while work occurs on the north levee. Parking areas accessing trails on the south side of Mill Creek are located near the office and at Bennington Lake, both on Reservoir Road.
“For safety, it is important for visitors to avoid the designated work zones,” said Justin Stegall, Mill Creek Project operations manager. “I want to reassure folks that these trail closures are only temporary while the work gets done to make our levees safe and sustainable for future inspections, maintenance and flood season operations.”
Rangers will post trail-closure updates and maps on information kiosks located at major trailheads and on the Mill Creek Project’s Facebook page www.facebook.com/millcreekdam.
This maintenance is necessary to meet National Levee Safety Program requirements in accordance with Corps headquarters regulations and policies. Non-compliant vegetation on levees blocks visibility for inspections, access for maintenance, hinders flood fighting, and adds uncertainty to structural performance and reliability, which increases risk to the public. The inability to inspect, maintain or flood fight could delay emergency response or contribute to risk of levee failure. Life safety is paramount for the Corps’ operations.
Restoring the federally managed section of the Mill Creek Levee System to meet national safety standards includes removing about 6 acres of woody vegetation from the landward side of the levees. Work will be conducted in two phases.
First, encroaching vegetation must be removed from the surface of the levee slopes and 15-feet outward from the levee’s design toe. Molinas Construction Company, of Portland, Oregon, a veteran-owned small business, was awarded the contract to conduct the phase-1 vegetation-removal work, which began Oct. 8.
Then, once the levee surface is visible for further inspection to fully identify needed repairs, a separate contract will be competed to conduct phase-2 work -- stumps and roots will be removed, and levee material will be replaced and compacted. After the vegetation-free zone is cleared and levee repairs completed, grasses will be planted on the levees to improve the aesthetics and benefit insects and wildlife.
Now that the landward-side levee maintenance zone is becoming visible, Corps staff have already been able to identify several conditions that will need to be addressed during phase-2 work or possibly sooner.
“Many of the trees being removed are rotting in their cores – placing them at high risk for falling onto the levee, and potentially visitors who may be walking along it,” noted Stegall. “One tree outside the maintenance zone already toppled over during high winds on Friday (Oct. 30). Additionally, a hazard tree was identified just outside the work zone and was removed.”
The levee was originally constructed in 1938-42 -- before the Walla Walla District was established in 1948. Early district records for the levee do not describe some of the things inspectors are now able to see in the maintenance zone.
“We’re finding things in the exposed area which will require further consideration before we start phase-2,” said Frank Wachob, Corps civil engineer and levee inspector. “Remnants of what appears to be abandoned utilities, including culverts and concrete debris, which we have not identified in our district records for this levee will need to be examined. We also plan to excavate test pits so we can confirm what materials were used for levee construction and determine the best methods to complete phase-2.”
Work-progress photographs, environmental-compliance documents, videos, fact sheet, map and other information about this levee-maintenance project is available on the Corps’website at www.nww.usace.army.mil/Missions/Projects/MillCreekLeveeMaintenance.aspx.
Release no. 15-074