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S.C. Sea Grant Consortium’s Low Impact Development Manual Fills Void in Coastal Region

Oct 20, 2017

By Joey Holleman, S.C. Sea Grant Consortium

The concept of low impact development (LID) is the same regardless of the location: mimic the natural processes of retention and infiltration to keep water as close to its source as possible.

But the details of LID change with the topography — water flows differently in a mountain setting than on a coastal plain. So when many of the best guides to LID were coming out of the rugged coasts of Oregon and Washington or the mountains of North Carolina, decision makers in coastal South Carolina needed guidance created closer to home.

“Our conditions are so different from Washington state or Asheville, North Carolina,” said Kim Jones, manager of the town of Bluffton’s Watershed Management Division. “How do we know that’ll work here? It’s really important to give the design community alternatives. There wasn’t enough information out there to help the design community in South Carolina.”

A neighborhood with plants and trees, and a brick pathway.

The low impact development manual created by the S.C. Sea Grant Consortium provides guidelines for engineers and developers incorporating concepts like porous sidewalks as design elements. Photo by April Turner, S.C. Sea Grant Consortium.

The S.C. Sea Grant Consortium, working with partners from the ACE Basin and North Inlet-Winyah Bay National Estuarine Research Reserve (NERR) Coastal Training Programs and the Center for Watershed Protection, decided to fill that void with a coastal South Carolina-specific manual. The partners pulled together stakeholders at meetings, workshops and research roundtables in a two-year project funded by a $329,943 grant from the National Oceanic and Atmospheric Administration NERR System Science Collaborative .

Vegetated islands are another design element typical in low impact developments. Photo by April Turner, S.C. Sea Grant Consortium.

What emerged in 2015 was the 425-page Low Impact Development in Coastal South Carolina: A Planning and Design Guide. The Consortium and partners then held three training workshop, where 140 engineers, stormwater managers and planners from the private and public sectors learned how to best use the guide.

LID uses concepts such as rain gardens, vegetated islands in divided streets and sidewalks constructed with porous substances that retain water. These steps reduce runoff that can overload stormwater systems and pollute waterways. They also can decrease infrastructure costs and the impact of development on local terrestrial plants and animals.

The South Carolina guidelines are certainly being consulted. The online version of the LID manual is one of the most popular items on the Consortium’s website, with the full document downloaded 38,000 times in 22 months.

The manual “is a user-friendly source of information that takes a very technical subject and makes it easier to understand for a variety of audiences,” said Jonathan Sherwood, community and regional planner for the Lowcountry Council of Governments, which covers Beaufort, Colleton, Hampton and Jasper counties. “The tools have already come in handy in my work.”

Joshua Robinson of Robinson Design Engineers is proud one of his projects is used as a case study in the guide. He noted the guide isn’t set up to be used to require or enforce standards. It’s more of a tool, one he consults “for design guidance, plant material recommendations and general rules of thumb.”