The University Record, February 18, 1997
U engineers help Corps of Engineers solve harbor
problem in Upper Peninsula's Ontonagon
Civil and Environmental Engineering Prof. Steven Wright (above)
works on a scale model of Ontonagon Harbor in the U-M Hydraulics
Modeling Laboratory. Elayne Crowe, graduate student in the College of
Engineering, and Jim Grueber, undergraduate student in Engineering,
helped Wright build the model and test four proposed solutions
designed to reduce wave heights in the Upper Peninsula
Trying to lessen the results of the legendary fury of Lake Superior storms is a task the U. S. Army Corps of Engineers wanted to address, and it recently turned to the U-M for help.
In the fall of 1995, one of Lake Superior's autumn storms damaged the harbor in the Upper Peninsula village of Ontonagon. In October 1996 the Corps asked civil and environmental engineering Prof. Steven Wright to evaluate four solutions it designed to minimize future wave damage in the harbor. Wright accepted the assignment and looked to turn the outreach project into a learning experience for a graduate student and an undergraduate student he later recruited to help with the project. He has done more than a half dozen other harbor assessments during the past 10 years.
Wright explains that Ontonagon Harbor has the misfortune of being nearly perfectly aligned with conditions that can create brutal waves. The mouth of the harbor opens slightly to the west-northwest. Winds blow unimpeded from Canada across Lake Superior and create massive waves that can reach heights of 10 feet to 20 feet by the time they reach Ontonagon. "The waves happen to be aligned with the harbor's entrance channel so they're coming straight down it," Wright says. "And unfortunately that's the worst wave condition in terms of interaction with the back of the harbor."
In the last couple of years, large waves rolled into the harbor causing damage to structures. Soil erosion occurred around the abutments of a state highway bridge at the back of the harbor that crosses the Ontonagon River. A pedestrian walkway along the harbor edge eventually collapsed, possibly due to soil erosion in the walkway's sub-base. Wright attributes the property damage to a combination of high waves and increased water levels in the Great Lakes. During the past few years, Wright says, water levels have increased by a couple of feet in all the Great Lakes.
Wright and his students built a scale model of Ontonagon Harbor to solve what seems like a straightfoward problem of reducing the height of storm-generated waves. However, Wright says, the problem is anything but simple. "You reduce the wave heights, but in practice it's much more difficult than that, because if you do one thing, make one change in a harbor, it may reduce the wave heights in one location but increase them in some other location."
Wright's team faithfully replicated most details of the harbor in the College of Engineering's Hydraulics Modeling Laboratory using video tape of the harbor and other physical descriptions. It took nearly six weeks to build a 10-foot by 40-foot scale model of the Harbor. A wave generator at the end of the test tank produces waves similar in height and other characteristics to those found at Ontonagon.
The Corps of Engineers asked Wright to test the four proposed solutions by themselves and in combination with each other. After conducting nearly all the tests, he plans to recommend two of the Corps' four proposed remedies.
Short of building a sea wall at the harbor entrance, Wright says the first thing that must be done is to lengthen the east jetty so it is the same length as the west jetty. He says leaving the jetties at unequal lengths gives waves a larger opening to enter the harbor. The second action is to create a boulder pile at the rear of the east jetty near shore, which he says also will absorb some of the lake's wave energy.
Although Wright was not asked to quote a price for the project, he says building the recommendations could cost up to $1 million. Wright has yet to determine if the two solutions should be tried together or alone. He expects to submit his findings in a couple of weeks.
Besides performing this work for professional and community service reasons, Wright likes assignments like this because it lets him involve students. The master's degree student and undergraduate working on the project were both in Wright's coastal engineering course. He hopes giving students real-life experience will better prepare them to be professional engineers, an environment where problems seldom have simple, black or white textbook answers.
"This is probably the first time that they've been exposed to problems that are not clean in their solution, that they'll be able to go through a calculation and get a definite answer at the end. So they get much more of a sense about what it may be like once they leave the University and get a regular engineering job."