Geology Department “hires”
Norwich seniors to design weir © May 4, 2012, Norwich University Office of Communications
The most frustrating part of creating a weir to help Norwich University students study water flow is that all of the designers will leave campus before they have a chance to help build it.
“I think that’s one of the toughest parts of a senior project,” said Logan Bessette, a civil engineering student who will graduate in May 2012, and one of five students trying to bring the project to life.
A weir is a barrier used to measure and sometimes alter the flow of water in a river or stream. In this case, students are designing a concrete structure to measure volumetric flow rate and other characteristics of a small creek that runs down Paine Mountain close to Norwich’s Northfield, Vt., campus. By measuring the height of the water flowing through a triangular cut at the top of the barrier, you can calculate volume over time.
Norwich geology and Norwich engineering students are going to be able to go up there
[and use the weir]
in 50 years.
civil engineering student
Their client and probable builder is Norwich’s own Department of Geology & Environmental Science, but the weir will be useful to other departments, including the Engineering and Engineering Management departments whose students took on the project.
“From the beginning, we though that Engineering would want to be involved,” said George Springston, a research associate with the Geology Department who has been closely involved with the project.
Understanding stream flow is a fundamental skill for environmental scientists, he said. An indoor weir they use in the classroom may help students understand basic concepts, but does not bring the complexity of a streambed into their learning. With that in mind, Springston and a few students fabricated a crude weir out of plywood on the same stream about three years ago. That structure is still standing and managed to survive the flooding of Tropical Storm Irene. It has seen better days, however.
“It was not intended to be permanent,” said Springston.
Civil engineering student Austin Brochetti said there are bigger problems than wear and tear on the plywood weir. Sedimentation appears to be building up on the upstream side of the barrier, and the pools that help regulate consistent flow are not deep enough.
“It is in extreme disrepair,” he said.
Civil engineering Prof. Adam Sevi, the project advisor, said the plywood construction has held up surprisingly well, but was never really large enough to accurately measure water flow. A larger concrete structure designed to withstand a 25-year flood will benefit all science and engineering students.
“That was the driver behind the project,” said Sevi. “Let’s build something permanent.”
Students hope to build a structure that doesn’t lead to erosion or impede natural flow of the river. They will be able to collect data over time and possibly include instruments that gauge turbidity and other water quality measures. Moreover, their weir will be built of concrete and metal and designed to last.
“Norwich geology and Norwich engineering students are going to be able to go up there [and use the weir] in 50 years,” said Bessette. “The calculations and accuracy won’t change.”
Geology & Environmental Science faculty initially came to the Engineering Department hoping for a project that would cost a few thousand dollars. The expense estimate has since eclipsed that, so they are trying to build a weir that follows recommendations from the U.S. Geological Survey, according to Brochetti. They hope this will make the weir more eligible for grants.
In preparation, students visited a U.S.G.S.-run weir located in Danville, Vt.
“We’re trying to follow their recommendations as closely as possible,” said Brochetti.
This means they pay attention to factors such as the depth and location of stilling wells, which are pools that ensure water collecting upstream and flowing downstream doesn’t alter the streambed. They have to be sensitive to nearby wetlands and consider the effects of any heavy equipment brought in for construction.
Height of the weir was also a factor, and designers considered both 3-foot and 6-foot barriers. Taller designs turned out to be both more usable and cost effective, but nothing higher than six feet was acceptable.
“Under six feet it’s not called a dam,” said civil engineering student Robert Loesner. “It’s called an impoundment, so it doesn’t require all the crazy permitting.”
Sevi said he expects concrete will have to be mixed by hand, and work accomplished by students. Richard Snyder, an engineering management student, said there will probably be at least one task that requires heavy equipment, however. There needs to be a trench to divert the water while concrete is poured.
“It’s going to require a backhoe,” said Snyder. “Otherwise, it's going to be a lot of digging.”
While they wanted to begin construction in summer 2012, it is more likely they will spend this time raising money, according to Sevi. Fortunately, the educational component should make the project attractive to organizations such as the National Science Foundation.
“[The Geology Department is] going to take our work and apply for educational funding,” said Sevi.