Making LID Practical with Standard Details

Lesley Brooks

Co-authored by Boris Minot.

Low Impact Development (LID) has emerged as a highly innovative and effective approach to managing stormwater quality at the source and as a means for better mimicking natural hydrology. While many cities are excited about LID techniques, an equal number of developers and engineers are afraid of the unknown. The City of Dallas identified the need to develop LID standard details in order to ease those fears and to ensure sound design and construction of LID applications. Freese and Nichols, in coordination with Hayden Consultants, researched several applications to assist the City, such as bioretention planters, bioswales, tree boxes, enhanced vegetated swales and permeable pavers. We applied this research and our interaction with several City departments to create eight standard details that provide clear implementation guidelines to contractors and engineers. These LID standard details are for:

  • Bioretention planters: With parking, and without parking
  • Curb Extensions: Corner and mid-block
  • Bioswales
  • Enhanced/Vegetated Swale
  • Tree box filters: Single, and in series

We also developed standard details for the various design components associated with each LID facility:

  • Stormwater Entrance: Depressed curb, trench drain and backless inlet
  • Stormwater Outlet: Depressed curb, trench drain and overflow structure (domed riser)
  • Piping: Underdrain, Anti-seep collar and Cleanout
  • Energy Dissipation: Splash pad with cobbles
  • Landscaping and Planting Media: Engineered soil, Mulch, and various plants and shrubs
  • Media Separation: Geotextile and Sand filter
  • Edge Treatments: Walls for pedestrian and vehicular applications
  • Check Dams
  • Signage
  • List of Recommended Plants

Freese and Nichols is also hosting a LID training workshop to further mentor City staff in the common applications of LID practices, operations and maintenance requirements of the LID facilities and conveying the message of LID to the public.

Freese and Nichols’ award-winning experience developing LID guidelines and knowledge of iSWM applications can help municipalities achieve their LID goals. For more information, contact Trey Shanks.

All images below courtesy of Philadelphia Water’s Green Stormwater Infrastructure Manual