Greening a parking lot with bioretention

Posted in: Environmental, Water


meadhunt-bioswales-1 I’ve been involved in stormwater engineering with Mead & Hunt for nearly a dozen years. When Mead & Hunt decided to move to a new 69,000 square feet building – I was thrilled at the invitation to be part of the development team. The new Middleton office and site were designed with sustainability in mind; the office is certified as a LEED Silver building. My task was to address parking lot storm water runoff. Mead & Hunt has always been committed to protecting the natural and human environment through innovative planning and responsible design. So it was important to me to find solutions that were green, environmentally-sound and attractive while also meeting our needs.

The new office is in a commercially developed area bound by well-travelled bike paths and beautiful city parks to the west and north. Just north of the bike path is a confluence pond and the Pheasant Branch Creek, where the stormwater runoff from our building and parking lot ultimately flow.

bioswaleOne of our goals in developing the new property was to protect the waterways with effective stormwater treatment. Bioretention treatment facilities were the preferred solution because of their ability to:

  • treat the stormwater
  • provide total suspended solids reduction
  • oil and grease treatment
  • provide groundwater recharge
  • provide infiltration of treated stormwater

meadhunt-bioswales-2Four bioretention areas were placed so that stormwater runoff is spread throughout the new office site. The drainage mimics “sheet flow” to prevent erosion and encourage infiltration. Bioretention areas located within the parking lot utilized curb cuts to encourage more treatment and infiltration of the stormwater runoff. The bioretention areas were carefully placed to avoid tree removal and adverse impacts to the surrounding bike path, sidewalks and parking lot.

The soils posed challenges in meeting stormwater treatment and infiltration requirements. The soil consist of clays and alluvial soils typical in former lakes and water bodies with high groundwater in the western two-thirds of the site. We were able to overcome the poor infiltrating soils with either removal, soil amendments or clay liners to protect groundwater.


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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