<P>58The Military Engineer ? July-August ? 2010 F ew people give much consider- ation to how their iPods, high- de?nition televisions or new cars traveled from manufacturing plants in Asia to their local big-box stores or automotive showrooms. The idea that their new purchases traveled across the ocean within the holds of freighters re- mains foreign even to many people fa- miliar with the concept of international trade. Nonetheless, that is exactly how most consumer electronics purchased in the United States enter the economy. And before they pull along dockside, the ships must pass through one of several U.S. Army Corps of Engineers (USACE) navigation projects. One such project is located along the coastal margin of the Paci?c Northwest, between the states of Oregon and Wash- ington, at the mouth of the Columbia River, where ships must pass between two massive rubble-mound jetties con- structed between the 1880s and 1917. This entrance, which was designed to train meandering ribbons of shallow channels into a predictable 60-ft-deep entrance channel, has long held the ominous moniker The Graveyard of the Paci?c due to its treacherous con- ditions and the more than 2,000 ship- wrecks that have taken place there since the mid-1800s. Vigorous wave-current interaction at the rivers mouth is caused by the con?uence of large ocean waves interacting with a prominent and spa- tially-variable ebb-tidal delta, a 2.5-M estuarine tidal range and the riverine ?ow regime of the Columbia River. This makes the coastal inlet one of the most dangerous in the world. Notwithstanding their robust con- struction, the jetties are not immune to the forces of the Paci?c Ocean. Both jet- ties have receded considerably due to more frequent and the ever-increasing strength of Paci?c storms. Of primary concern are critical portions of the North Jetty (Washington) and the South Jetty (Oregon), which could breach during a large storm event. Engineers have seen steady deterioration along several key reaches of both jetties. If either struc- ture were to fail and ocean currents were able to ?ow unabated through the jetty, sandy deposits located on the ocean side of the structure would be transported through the jetty and deposited directly into the navigation channel. A breach would cause the channel to begin ?ll- ing in, immediately affecting navigation at the mouth of the river, thus requiring emergency jetty repairs and dredging to restore channel depth. A Hub of Commerce The Columbia River and the Snake River, the Columbias largest tributary, compose the primary export gateway for 11 states. For example, 25 percent of wheat exports from Kansas come down the Columbia River and more than 47 percent of total wheat exports from the United States is shipped via Columbia River ports. It is the largest wheat and By Matt Rabe, Eric Bluhm and Fritz Moritz Jetty Maintenance in the North Paci?c A victim of ever-increasing Paci?c storms, the North Jetty at the mouth of the Columbia River has lost more than 2,100-ft to erosion since it was completed in 1917. U.S. Army Corps of Engineers photo by Billie Johnson</p> <UL><LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/1/1/">Front-Cover</a></LI> <LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/2/2/">Inside-Front-Cover</a></LI> <LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/3/3/">Page-1</a></LI> <LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/4/4/">Page-2</a></LI> <LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/5/5/">Page-3</a></LI> <LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/6/6/">Page-4</a></LI> <LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/7/7/">Page-5</a></LI> <LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/8/8/">Page-6</a></LI> <LI><a href="http://www.stallionpublishers.com/publication/609/tofzxaosm/9/9/">Page-7</a></LI> <LI><a 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