[a hand-crafted steel cutterhead of the Dredge Oregon. The specular silver sheen on the backside (click on image for detail) is a nickel plating added to extend the life of the cutter as it rips and churns through the shifting sediments of the Columbia River.]
Back in February of this year I had the opportunity to tour the Dredge Oregon, the Port of Portland’s primary dredging vessel for maintaining shipping channels in the Columbia River. At the time of the tour, the Dredger wasn’t was not actively dredging. Rather it was in a more convalescent state, docked to its winter residence of floating barges at the Port’s navigation office and maintenance yard on Swan Island in NE Portland (image above).
In 1891 Oregon Legislature created the Port of Portland and empowered it to dredge and maintain the Lower Columbia River channel (from the Pacific Coast to Portland), at a depth of 25 feet. Today the Columbia River is now maintained at a depth of 43′ (as seen in NOAA charts). In a long-standing symbiotic relationship, the Port of Portland works as a primary contractor for the Army Corp of Engineers to dredge where the Army Corp determines is necessary.
[A portion of the Port of Portland's 8,000' of 30" diameter pipe, through which dredged material is suctioned and transported to a multitude of upland and in-water sites]
During the winter months, the Dredge Oregon and other dredging equipment gets repaired, maintained and upgraded. Touring the ship one could see its many mechanical organs being worked on, or otherwise being entirely gutted (below) to replace its aging diesel engines.
[Above: the steel cutterhead would be attached to end of this boom arm when actively dredging]
The Dredge Oregon has swept through the Columbia River during summer months for years, carrying up to 82,000 gallons of diesel in its berth. The 800 horse power cutter motor and 150 horse power swing motor are able to cut a 450 ft wide expanse along the bottom of the Columbia. With its 33″ inner diameter suction pipe and 16 cylinder 4,950 hp pumping engine, it can dredge 2,000-3,000 cubic yards of material per hour. It is the “largest carbon producer on the river” and its now defunct diesel engine used about 4,200 gallons of fuel per day . Last year, 2.2 Million dollars were spent on fuel related costs for its four to five active months of service.
Walking through the Russian doll-like passages of this vessel – operating systems nested within and adjacent to other systems, semi-encased in what masquerades as a durable body – I was struck by the much larger construction of migratory patterns in which it partakes, a meshwork of industrial-geologic-climatic trajectories.
During the fall, winter and spring, precipitation inundates the Northwest and the Columbia River, activating the landscape’s hydro conveyor belts which re-disperses sediments throughout the region. As spring rolls around, the U.S. Army Corps re-traverses the Columbia, articulating a fresh round of bathymetric surveys. They observe new shoals and changes in the river, and in order to regain the desired form of the deepened shipping channel, they generate a rigorous dredging agenda for the 44 person crew of the Dredge Oregon to complete between June and September. Thus a counter, or return material migration is set in motion, a trajectory running in the opposite direction. And with that counter energy flow comes a nebulous logistical stream. Huge amounts of stored solar energy is suctioned out of distant landscapes, distilled into diesel and pumped into some ocean-going vessel that transports it to the Northwest, where it is then pumped into the Dredge Oregon so that it can pump and displace about 5 million cubic yards of sediment per year. The migration pattern is repeated each year
The Dredge Oregon, rain, diesel fuel, lubricants, grain terminals, graveyard shift personnel, and steel cutterheads have literally manufactured and congealed large portions of Portland’s landscapes through the push and pull of these migrations, like Swan Island (where Dredge Oregon docks for the winter), the Portland Airport, the River Gate District, parts of Hayden Island, and sections of Interstate 84.
The points where these opposing trajectories come together, where material jumps from one aggregated trend into the another is fascinating. It’s the moment of return where new alliances get formed. Entropy runs wild, as does design opportunity. And the migration cycle builds over time…”the Corp is never caught up with dredging”. I asked if the deeper channel induces an aggregating cycle of dredging; if the lower Columbia’s novel shape, its deep water channel (and all other such channels around the globe) in turn affects the rate at which dredging needs to happen: “The river finds a new type of equilibrium, it adjusts into being something else.” I’d really like to know more about that.
[Map diagrams for dredge operations on the Columbia. Still learning how to read these. Anyone know?]