International Dredging Review

International Dredging Review

A redevelopment project in Portland Oregon won the 2014 Project Excellence Award in the large category from the American Society of Civil Engineers (ASCE) Coasts Oceans Ports and River Institute (COPRI). The Zidell Waterfront Cleanup restored a contaminated site along the riverbank.

The site is a 30-acre parcel located in the heavily urbanized South Waterfront District in Portland along a one-half mile stretch of the Willamette River. The land has been home to continuous industrial use for nearly 100 years including ship building ship dismantling and now barge building by Zidell Marine Corporation. Soil and sediment at the site was contaminated with asbestos heavy metals polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The cleanup effort involved 32 acres of upland remediation and 13 acres of sediment and riverbank remediation. All in-water work was restricted to a four-month work window to protect threatened fish species. Total site remediation construction costs are more than $20 million to date.


A redevelopment project in Portland Oregon in the heavily urbanized South Waterfront District cleaned up and capped contaminated sediment along the Willamette River.

Maul Foster & Alongi Inc. of Vancouver Washington was the environmental engineer and worked with an integrated team of engineers and environmental specialists of various disciplines to prepare a complex remediation design to address the requirements of the Oregon Department of Environmental Quality. The remedial design included removing areas with the highest levels of contamination and isolating areas of low-level contamination. Site remediation of the riverbank and sediment included 15000 cubic yards of riverbank excavation and dredging to remove sediment with high levels of contaminant and to stabilize contaminated riverbanks that were over-steep and unstable. The placement of 130000 cubic yards of clean sand and riprap over 12 acres of river bank and bottom isolated the low-level sediment and soil contamination which was to be left in place. Riverbank stabilization was required for more than 2700 feet of waterfront. A specialty low profile sediment cap was designed to allow barge launch operations to continue in a oneacre area of the slipway barge construction area for Zidell Marine.

Quigg Bros Inc. of Aberdeen Washington was the general contractor working with HME Construction Inc. of Vancouver Washington and Three Kings Environmental Inc. of Battle Ground Washington. Sediment capping was completed by three derrick barges working at the same time. Dredging and bank excavation was performed by land-based fixed-arm excavators in areas that were contained using turbidity curtain.

Several challenges were addressed during construction. A 700-foot segment of the riverbank in the middle of the site was required to be completed in the first six-weeks of the project so that the construction of TriMet’s Tillikum Crossing lightrail bridge ($140M) could begin. In-water construction was required to work on a wire-anchor system because the use of spuds was prohibited within the sediment cap area. The sediment cap specification required sand to be spread at the water surface in individual onefoot lifts to prevent a bearing failure of the underlying soft river bottom sediment (which was contaminated). The accuracy of sand cap placement was closely monitored by the engineer and verified by diver-collected sediment cores and daily hydrographic progress surveys.

In addition to general project construction coordination Quigg Bros Inc. of Aberdeen Washington performed sand and riprap sediment cap placement reactive core mat placement bank excavation/regrading bank riprap placement and pile cutting/removal. Quigg provided two derrick barges two tugs three material barges one wheeled loader and three excavators. The D.B. Skookum is a pedestal mounted 3900 Manitowoc lattice boom crane and was used for placement of sand and riprap for the sediment cap. The Skookum was equipped with a four-cubic-yard smooth lip clamshell bucket and an eight cubic yard rock skip box. The D.B. Aberdeen has a crane-mounted lattice boom with 50-ton capacity which was used for piling removal and placement of the reactive core mat in the low-profile sediment cap area.

HME Construction Inc. of Vancouver Washington was responsible for placement of sand and riprap for the sediment cap and the barge delivery of sand and rock materials to the work site. HME used two derrick barges one tug six materials barges one spud barge and four loaders for the placement of the sand and riprap sediment cap. The D.B. Sea Vulture is a pedestal mounted 4600 Manitowoc lattice boom crane with 100-ton lift capacity which was equipped with a 12-cubic-yard smooth lip clamshell bucket and a 12-cubic-yard rock skip box. The D.B. Sea Hawk is a pedestal mounted 3900 Manitowoc lattice boom crane with 50-ton lift capacity and was equipped with a five-cubicyard smooth lip clamshell bucket and a nine-cubic-yard rock skip box.