HAL helps Salt Lake City and others comply with new stormwater regulations

Changes in Utah’s MS4 (Municipal Separate Storm Sewer System) permit program, which aims to reduce pollutants entering streams, rivers, and lakes as a result of storm runoff, became effective July 1, 2020.

The new regulations include provisions for Low-Impact Development (LID). LID is a stormwater management paradigm that seeks to minimize the off-site impacts of runoff quantity and quality associated with land development by managing a prescribed portion of stormwater on site. LID solutions include rain gardens, bioswales, permeable pavements, green roofs, and more.

The most notable new regulations are:

  • A process must be in place to evaluate LID approaches for all development projects greater than 1 acre or increasing impervious area by more than 10%. If LID is not feasible, supporting data and justification must be provided.
  • Development or redevelopment projects disturbing more than 1 acre or increasing impervious area by more than 10% must prevent off-site discharge for the 80th percentile event using LID techniques.

Hansen, Allen & Luce (HAL) has advised Salt Lake City, Sandy City, and Salem City on design standards, criteria, and solutions that allow them to more effectively manage stormwater and comply with the MS4 permit requirements.

Salt Lake City’s study area is particularly large and diverse, covering mountain watersheds (Parleys, Emigration, Red Butte, and City Creek Canyons), dense urban developments, and extensive industrial zones. To complete the work faster, HAL is dividing the work into several drainage areas that multiple firms can analyze simultaneously. HAL is also preparing a project roadmap—including report templates, hydrologic design criteria, and modeling software—to ensure consistent methods and products across several teams.

Detailed LID guidance is available in A Guide to Low Impact Development within Utah (PDF) from the Utah Division of Water Quality.

If you would like to discuss LID and how it impacts your next capital project, contact Kayson Shurtz, P.E., at info@hansenallenluce.com.

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