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Title: Final Navigation Channel Feasibility Report and Environmental Assessment : Williamsport
Authors: United States. Army. Corps of Engineers. Alaska District.
Keywords: Williamsport (Alaska)
Iliamna Bay (Alaska)
Environmental management
Environmental protection
Publisher: United States. Army. Corps of Engineers. Alaska District.
Abstract: The Williamsport-Pile Bay Road has served for hundreds of years as part of an overland route from Cook Inlet to the Iliamna Lake region of southwestern Alaska and on to Bristol Bay and the Bering Sea. Williamsport is the name of the undeveloped terminus of the dirt road, owned and maintained by the State, which leads from Pile Bay on the southeastern shore of Iliamna Lake over ,the Chigmit Mountains to the western shore of Cook Inlet. Williamsport is inaccessible by sea except for brief periods at the peak of extreme high tides which occur a few days each month. In spite of this extraordinary limitation, landing craft approach Williamsport regularly to offload cargo bound for the communities of Iliamna Lake. The road is also used for truck transport of commercial fishing vessels from Cook Inlet to Iliamna Lake, where the vessels can sail to Bristol Bay via the lake and the Kvichak River. The owners of these vessels prefer to take advantage of more affordable maintenance, repair, and storage services on the Kenai Peninsula (eastern Cook Inlet), versus using much more expensive arrangements in Bristol Bay. A navigation improvement to increase access to Williamsport and enhance the transfer of cargo would significantly reduce transportation cost for cargo and fishing vessels. This report documents a detailed study of these problems and alternative solutions. The report recommends excavation of a channel 2,700 meters (m) long in Iliamna Bay. The channel bottom would be 30 m wide at 0.5 m below Mean Lower Low Water (MLLW). The channel would end at Williamsport with a turning basin, 55 m long and 55 m wide. The turning basin would provide access to a recommended sheet-pile bulkhead dock, 30 m long, and an adjacent paved launch ramp 8 m wide. These features would save an average $1,525,300 each year in transportation and related costs. The recommended plan would cost $3,822,000 to construct and an average $185,000 per year to maintain. This maintenance cost includes annual grading of the dock, ramp, and staging area; annual surveys the first 4 years, then every 5 years; maintenance dredging every 5 years; replacement offender piles, ramp concrete, and sheet-pile cathodic protection every 10 years; and replacement of the sheet pile after 30 years. Average annual benefits exceed average annual costs by a ratio of 3. 1 to 1.
Description: Feasibility Report and Environmental Assessment
Rights: Approved for Public Release; Distribution is Unlimited
Size: 362 pages / 18.75 MB
Types of Materials: PDF/A
Appears in Collections:Environmental Documents

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