What does stormwater treatment have to do with my transportation project?

Posted in: Bridges, Environmental, Municipal, Transportation

Black Earth Creek in the Village of Cross Plains

When we talk about highway and street projects, we often hear about green streets, complete streets, bike lane, pedestrian friendly, multi-use paths and sustainability, but what about post-construction stormwater treatment?

There are many factors that determine whether stormwater treatment is required for a transportation project, including discharge to environmentally-sensitive areas like trout streams, the conversion of swale drainage to curb and gutter drainage, significant road widenings, sensitive or endangered natural resources or local stormwater ordinances. Working with your state Natural Resources agency and local government will help understand and identify the targets for your stormwater treatment prior to creating a plan.

Incorporating stormwater treatment into a linear highway project can be a challenge. However, there are a few strategies you can use to incorporate stormwater treatment facilities into existing highway right-of-way such as swales, bioswales, porous bike lanes, native plant filters, catch basin sumps, infiltration areas and porous pavement.

For example, if you are in a cold water community and are required to mitigate for thermal impact, consider infiltration and bioretention or rock cooling cribs. Rock cooling cribs were designed for a Wisconsin Department of Transportation project on Black Earth Creek in the Village of Cross Plains, a local trout stream and community treasure. The site had high groundwater and could not support a bioretention facility, so rock cribs were designed for water treatment and cooling prior to release to the local trout stream. This project used an off-site location to coordinate with the local community and Wisconsin Department of Natural Resources.

Lacy Road in the City of Fitchburg

When exploring the stormwater treatment options that may be suitable for your project, it is important to consider the soils, groundwater depth, long term maintenance costs, construction cost and overall design life. An example of a linear stormwater treatment strategy for a road project is the reconstruction of Lacy Road in the City of Fitchburg. Our team explored the use of porous pavement as well as the use of bioswales to meet the local stormwater ordinance treatment goals. A cost benefit analysis was performed to analyze what option is most suited for the project. Our final recommendation was to use a combination of bioswales and porous pavement as it was the most cost-effective solution for the project that best utilized the space within the new right-of-way.

For more information on stormwater treatment guidance in Wisconsin, don’t hesitate to contact me. I look forward to discussing stormwater solutions with you.

Anne Anderson, PE

About the Author

Anne Anderson, P.E., specializes in stormwater management, permitting, planning and municipal infrastructure projects. As a project manager and design team member, she has been involved in projects in the public and private sector throughout the Midwest. Read “Finding fulfillment beyond numbers: Mead & Hunt engineer taps new capabilities” that shares Anne’s love of storm water issues.

Read more posts by Anne Anderson, PE

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