Re-engineering history Part III: Soft engineering presence grows
The Essex Region Conservation Authority in Ontario, Canada is close to restoring a 1,500-foot section of Windsor city waterfront using soft shoreline engineering.
The technique is used to create wildlife habitat, cleanse storm water, improve public access and make the shoreline more attractive where hard engineering, such as sheet steel and cement, have controlled erosion previously.
“Windsor has primarily been an industrial center as Detroit has,” said Matthew Child, the authority’s watershed restoration director.
The authority has completed 10 to 12 similar projects costing $400,000 to $2 million. The efforts on three of those projects have transformed a section of industrial Windsor waterfront into a continuous, natural shoreline. Previously, it was a railway yard.
“Around the automotive sector, [there was a] lot of loading and unloading of materials by ship,” Child said. “Those materials were often directly loaded on to railcars.”
The shoreline was bleak—a section of rail lines and boxcars, where hydrocarbons were spilled on the ground and wood crib walls sprouted in place of vegetation. The walls prevented erosion and created a draft deep enough for vessels to dock close to shore.
But water seeped in behind them, creating erosion and mixing with soil used by the railyards, Child said.
The authority replaced the wood with limestone in 2006.
Rock islands created offshore spawning habitat for fish. Shelter structures were built to protect the site from the wave action of passing freighters. The shoreline was reconstructed into gullies and ridges that provide additional habitat for fish and wildlife and a recreational trail now runs along the shore.
Looking for opportunity
Patrick Doher, a civil engineer with environmental landscape design firm JJR, said managers will have to do something with shorelines in the region anyway. Hard shoreline structures are starting to deteriorate. Doher used soft engineering techniques on the U.S. side of the river along Gabriel Richard Park’s river edge and in sections of William G. Milliken State Park and Harbor in Detroit.
“We do need to think more broadly on how we improve our shorelines in general,” he said. “We do need to think more along the lines of environmental solutions that not only meet the expectations of the shoreline and land use itself, but the environment and opportunities for soft engineering,” Doher said.
The technique is growing.
“It’s no longer unique to consider a soft shoreline treatment for these projects,” Child said.
A few years ago, soft shoreline engineers had to convince municipalities to invest a premium in the practice.
“I think as it becomes more acceptable and common… it just becomes a normal construction or standard construction practice,” Child said.
Great Lakes pose challenges for soft engineering
Waves and ice that scour the Great Lakes shorelines are restoration challenges, said Nativescape’s Chris Lehr, who helped soft engineer the Detroit Edison River Rouge Power Plant site’s shoreline. Powerful waves can overwhelm native plants installed to stabilize the shoreline, and ice break up in the spring can pose issues.
“Whether it’s a major river course or lakeshore of any kind, Great Lakes included, you really have to know what is going on with the ice because it can just virtually take the whole thing away in one fell swoop,” Lehr said. “If it’s attached to these soft engineering materials, it can just take those right away.”
Lehr said the techniques might be more appropriate for slopes experiencing erosion above a Great Lakes shoreline and is less appropriate for rocky shores that do not need stabilization, such as parts of Lake Superior.
Some states now require soft shoreline techniques first
Before Wisconsin landowners can control erosion of stream banks, they must calculate their site’s potential for erosion.
If the score falls below a threshold, landowners are restricted to soft techniques said Daniel Houston, water management specialist for the Wisconsin Department of Natural Resources.
Use of “hard armoring” techniques, including rip rap still requires landowners to use bioengineering—natural materials like fiber logs and branch or plant bundles, to prevent soil erosion above the waterline. The restrictions are similar for lakefront landowners, though Wisconsin uses a storm wave height to determine if bioengineering should be used. Landowners are required to vegetate areas above the waterline even if they prove they are eligible to use hard engineering in their construction site.
Great Lakes states including Michigan, New York and Illinois encourage use of soft engineering techniques, but do not require them.
Editors note: This is the third in an occasional series of stories looking at soft shoreline engineering.