Lodge Creek Culvert Replacement
The existing 4-foot diameter corrugated metal pipe culvert that conveyed Lodge Creek under Via Kachess Road failed during heavy rains in early spring 2016—undermining the existing road fill and pavement.
The project required close coordination with resource and regulatory agencies to meet the aggressive four-month design and construction schedule. This required regular coordination meetings with Kittitas County, the USACE, DOE, WDFW, USFWS, NMFS, USFS, and Yakama Nation. This coordination included developing a multi-disciplinary team consisting of experts in design (e.g. geotechnical, structures, roadway, and construction), environmental (e.g. biology, permitting, and cultural resources), and construction.
The project geotechnical conditions underlying the road embankment were composed of fine silt and organics. There was also a high value wetland upstream of the existing failed culvert and a degraded scour condition downstream of the roadway. The downstream condition created a plunge pool fish passage barrier—which adversely impacted stream and riparian habitat—and had a risk of draining the upstream wetland if not designed and constructed to avoid head-cutting and channel instability.
During the first workshop, Atkinson evaluated the proposed open-bottom design and determined a four-sided box culvert would eliminate many of the associated geotechnical risks. Atkinson also proposed a three-day roadway closure to remove and install the new culvert—based on production rates at the recently completed Jovita Creek culvert replacement in Auburn, WA. Atkinson installed a new 40-foot-long, 19-foot-wide, closed-bottom, 4-sided precast concrete box culvert together with upstream and downstream riparian habitat. The new culvert better conveyed large Lodge Creek flow events and improved fish passage. The new roadway provides reliable residential and emergency access to homes along Lake Kachess.