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Corps Beginning Maintenance
Dredging of Columbia River

by Staff
The Daily Astorian, June 15, 2009

The U.S. Army Corps of Engineers has begun its annual maintenance dredging season in the Columbia River and on 12 Oregon coastal projects.

Portland District's two hopper dredges and several private industry dredges will divide the work load.

The Corps recently awarded the North Coast hopper dredge contract to Great Lakes Dredge and Dock to dredge 4.4 million cubic yards at the mouth and in the lower Columbia River, and at the Coos Bay entrance.

The hopper dredge Terrapin Island will begin work in the Columbia River near the end of June and will work in all three areas until early December. The Corps will award a small business pipeline contract next week to dredge 62,000 cubic yards of material from the Garibaldi and Depoe Bay boat basins from mid-July to mid-September.

The Corps will advertise the North Coast mechanical bucket dredge contract in July. The work involves dredging 225,000 cubic yards of material from three locations on the Columbia River: Chinook and Baker Bay from September to October, and the Westport Ferry Crossing from November to February.

The government hopper dredge Essayons will return from California to resume work at the mouth of the Columbia River next month. The dredge will work in conjunction with the contracted hopper dredge Terrapin Island at the mouth and in the Columbia River through September.

Essayons was delivered to the Portland District in 1983 and was the last dredge to be built for the Corps of Engineers. Essayons recently became the first Corps hopper dredge to be repowered since 1979. The dredge was outfitted with all new engines, resulting in additional horsepower and lowered emissions, as well as extensive upgrades to its machinery monitoring and electrical power management systems, making it the most technologically advanced ship in the U.S. government hopper fleet.

Hopper dredges move like other ships, but very slowly when dredging. Signals on the main mast alert others in the area when the dredge is working and restricted in its ability to maneuver. The daytime signal is a black ball over a black diamond over another black ball. At night the signal is a red light over a white light over another red light. When the dredge's hopper is loaded, it may move much faster and turn frequently as it maneuvers in and out of the channel to reach the dredged material relocation site.

The Corps warns mariners to keep a reasonable distance from a hopper dredge when it is operating, as the dredge poses several hazards. Propellers at the stern and on both sides near the bow generate strong water currents that can capsize smaller vessels. Streams of water are automatically released from holes at either side of the bow that are powerful enough to capsize a boat, and large volumes of water may overflow from the hoppers at the center of the dredge. Dredges monitor marine VHF radio and may be contacted on channels 13 or 16 if necessary.

Annual maintenance dredging of Oregon's coastal river entrances and navigable waterways is essential to keep these areas clear of shoals and allow for safer transit of commercial and recreational watercraft. A combination of regular budget allocations and stimulus funds made this year's dredging contracts possible.

Other Corps projects will take place in Coos Bay, Brookings, Port Orford, Toledo, Florence and Charleston.

Corps Beginning Maintenance Dredging of Columbia River
The Daily Astorian, June 15, 2009

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