Trends Summer 2017 - Page 5

Images of Carson Park Causeway in Eau Claire, Wisconsin Widening the causeway means dredging sediment – almost 11,000 cubic yards – and adding rock riprap to support the causeway and armor the lake banks to reduce erosion. Dredging and filling in the navigable waters of Half Moon Lake involved the U.S. Army Corps of Engineers and Wisconsin Department of Natural Resources (DNR). The Wisconsin Department of Transportation (WisDOT) is involved because it is administering the project, and the U.S. Fish & Wildlife Service had a permitting role because of migratory birds and the threatened Northern long-eared bat. The DNR supported improving the lake but had concerns about the sediment and fill. “That was very much scrutinized by the permitting branch of the DNR even if the recreational branch was fully supportive,” Solberg said. Ayres structural engineer Dan Sydow said to receive a DNR permit, the City needed to sample and test the lakebed material. Tests found a low level of heavy metals in the sediment, likely from past algae-control treatments. That discovery added complexity – and more permitting – to the project. Instead of simply having the contractor dispose of the sediment, the material now would need to be hauled to a permitted disposal site or landfill, which would increase project costs. “From a permitting perspective this was unique,” Sydow said. “We now were dealing with the low-hazard waste disposal process in addition to doing all this filling into the lake.” An unused site near the City’s wastewater treatment facility had been approved for low-hazard material for a different project. DNR solid waste staff worked with WisDOT to determine how to use the previous permit for this new project, following a different process. “It’s an example of what can get done when you get not only regulatory agencies but recreational and resource agencies and multiple divisions of government together to brainstorm what can happen,” Solberg said. “When it’s all done we’ll have a better resource and better access to that resource.” DNR resource staff asked for larger pipes under the causeway in addition to the larger bridge to improve water exchange. Solberg said accommodating that request helped relieve agency anxieties over additional fill. “They were pragmatic on their side, and we were pragmatic │5