DT Design Studio presents to Engineers' Club of Memphis

Bioswale in the parking lot of Heifer International Headquarters featuring native grasses and perennials.

Dalhoff Thomas design studio and the Corradino Group were featured as the program speakers for the December 1st meeting of the Engineers’ Club of Memphis at the University of Memphis Holiday Inn where we spoke about green infrastructure principles and our winning project for the recent  Memphis-Shelby County Low Impact Development Design Competition. Henry Minor of Dalhoff Thomas began the presentation with an overview of green infrastructure practices and explained the rules and background of the LID Competition. To help everyone understand the various types of green infrastructure, we presented images of rain gardens, pervious pavement, and bioswales, such as the image above of a bioswale in the parking lot of Heifer International Headquarters in Little Rock, AR. We asked the audience how many felt this bioswale was aesthetically pleasing, and only two people liked the way it looked. The public perception of how native plants look in green infrastructure elements such as rain gardens and bioswales is one of many barriers that landscape architects and engineers must strive to overcome with better designs. Educating municipalities and the public about a different design aesthetic in the landscape, one that is more natural and less manicured, is critical to helping them understand the wildlife habitat and stormwater quality benefits provided by green infrastructure.

Perspective image of the LID Competition cottages showing the aesthetic value of the rain gardens and native plant material.

Sam Henry of Dalhoff Thomas and Joel Morrill of the Corradino Group continued by giving another great presentation of our first place project for the LID Design Competition and explaining the technical aspects of the green infrastructure design. Joel, the civil engineer on the team, explained how the rain gardens distributed throughout the site were capable of capturing a total of 98,000 gallons of water and removing 80% of the total suspended solids (TSS) in a 1” rain event. For a given gallon of stormwater runoff to be remediated, it is 2.4 times more cost effective to be treated with our green infrastructure design than with traditional grey infrastructure. In addition to the LID Design Competition project, Sam and Joel provided additional examples of recent green infrastructure projects in Louisville, KY and at City Hall in Germantown. See the rendered site plan below showing the rain gardens and new signage to be installed at City Hall. The engineers in attendance were very interested in the subject matter and asked several specific questions about how the rain gardens would perform in larger storm events and how maintenance would be handled. Sam explained that larger storm events would bypass the rain garden treatment system through an emergency overflow pipe, and maintenance would be performed by the homeowner’s association. Providing solutions to these questions and more is necessary to achieving a successful green infrastructure system. The EPA provides a list of resources to help answer the question, How Can I Overcome the Barriers to Green Infrastructure?

Rendered site plan of the future rain garden project to be constructed at Germantown City Hall.