Lower Willamette River – Portland, OR
CRETE prepared the design and bid documents for the removal, capping, and stabilization of 1,700 lineal feet of riverbank fronting an active steel mill on the eastern bank of the Lower Willamette River within the Portland Harbor Superfund Site. Work was conducted through a Voluntary Remedial Investigation Source Control Measures Agreement between Oregon Department of Environmental Quality and the Owner. Bank and beach material was impacted with PCBs and metals, with contamination extending landward of the river beneath the active steel mill. Complete removal of bank and beach material was restricted by the facility and in these areas the design included capping and stabilization. Excavation and disposal included about 17,000 cubic yards of contaminated material.
The design required a balance between a more robust rock armor stabilization that is necessary given the site geometry and the desire to adequately stabilize impacted soil in place, and providing a habitat benefit to the design. Critical plant operational facilities are in close proximity to the riverbank which restricted the ability to flatten or change the relatively steep slopes. Extensive geotechnical, seismic, and erosion analysis were conducted to ensure that the design would remain in place under dynamic conditions. The design required less conventional ways to provide habitat benefits. Elements such as minimizing the footprint of rock armor by making it as steep as practical, providing higher value habitat as close to the uphill and beach extents of the armor as practical and providing habitat enhancements to fringe areas of the site work. A large portion of the work was below ordinary high water which triggered extensive permitting and restrictions on the timing of construction activities. Construction associated with the remedial action began in July 2015 and was completed in early 2016.
- Regulatory negotiations – Oregon DEQ
- Permitting – in-water cleanup, construction stormwater
- Shoreline and sediment cleanup
- Construction plans and specifications
- Construction oversight
- Negotiated and designed a shoreline cleanup that protected critical plant operations
- Negotiated a self-mitigating cleanup