Meeting Date: Monday, June 4, 2018
Guest Speaker: Mr. Tom Bourque, P.E.
Topic: And When the Landfill Swims with the Fishes
The City of Port Angeles Landfill is located adjacent to Olympic National Park on the Strait of Juan de Fuca in Washington State. Three solid waste cells (west, middle, and east) located behind and within the 135-foot sea bluff had been closed for 20 years as new cells were constructed and operated behind (inland of) them. Bluff and seaward cell slope failures resulted in refuse discharging onto the beach, precipitating a 300-foot seawall to stabilize the west and middle cells in the mid-2000s. Subsequently changed wave dynamics off the sea wall eventually threatened the middle and east cells. Accelerated bluff erosion through block failures and wave erosion penetration into the east cell had reduced the seaward bluff wall thickness from the original 100 feet (back from the “edge” of the bluff) to as narrow as ten feet. Bluff erosion was also changing due to increasing storm intensity and higher high tide levels, commonly attributed to climate change observations. New cell configurations were developed based on slope stability, seismic loading, groundwater conveyance, projected bluff erosion patterns into the landfill site, and new landfill cover system approaches. The tallest mechanically reinforced earth wall ever built in Washington State was constructed, including being integrated into the new solid waste landfill cover system. Construction in 2014-15 occurred on the beach, within the bluff, and within the landfill site. In addition, endangered species were a significant issue. Stream and beach control and restoration were required due to several species including salmon and Taylor Blackback Butterflies. Three tribes participated in the project as well as the City of Port Angeles, Washington Department of Ecology, Army Corps of Engineers, US EPA, state resources agencies, and several community groups. This project was the largest solid waste relocation project ever undertaken in Washington State history.