Not Your Everyday Stormwater System

October 19, 2020

While the design of swales, infiltration practices, ponds or storm sewer can be common practice, Regenerative Stormwater Conveyances (RSC) systems can be used as a substitute in many situations and provide a number of benefits. RSCs offer a unique solution to addressing water quality and quantity concerns.

RSCs are synonymous with regenerative step pool storm conveyance, regenerative stream channel and biofiltration conveyance, along with many other names. The similarity with all of these systems is that they work to convey and treat stormwater runoff using a series of riffles and pools of sand/woodchip media beds. RSCs can be used to stabilize erosive channels or as a stormwater system for new developments or even as a retrofit to old and/or failing systems.

RSC systems offer an innovative solution to addressing water quality and quantity concerns.

RSC systems offer an innovative solution to addressing water quality and quantity concerns.

How do RSCs work?

RSCs consist of a series of riffles and pools. The diagram below shows a typical profile section of an RSC. Stormwater enters the system into a pool and depending on the characteristics of a particular site, this could be a plunge pool filled with riprap or it could be the start of sand/woodchip media beds. Once the runoff enters this bed, it will either infiltrate (small storms) into the media bed or it will start to pond (larger storms).

As the pools start to pond in larger storms, the runoff will spill over a parabolic-shaped weir constructed of cobbles. These cobbles will vary in size but typically have a diameter of approximately six inches. Once the ponding water overtops the weir, it will move over and through the cobble riffle and cascade down a set of large boulders into a second pool. When the runoff reaches the second pool, the process repeats itself with multiple weirs and pools, depending on the length and gradient of the system, until it reaches its ultimate discharge point.

This diagram shows the standard components of an RSC system.

This diagram shows the standard components of an RSC system.

The Benefits of RSCs

RSCs provide significant energy dissipation, which is why these systems are often used to replace degraded, highly erosive channels and ravines. The slowing of water as it moves through the system allows for vegetation growth and reduces the chances of future erosion. The rock weirs help to spread out the flow path of runoff, which can help pass larger rain events in a safer manner. The pools help to infiltrate stormwater and settle out any pollutants that enter the stormwater system. The pools also provide detention during rain events that will help reduce flooding downstream of the system. Not only do RSCs provide all of the benefits mentioned above, but they also provide a diverse habitat for the surrounding wildlife and can be aesthetically pleasing.

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raSmith’s engineers have assisted clients on projects using RSCs for stormwater management solutions. For example, RSC was instrumental in the stabilization of the Reck South Ravine in the Village of Somers, Kenosha County. The treatment included regrading to create infiltration pools upstream of nine rock riffles and revegetating the banks with native grasses and forbs.

Along with using RSCs, our experts are experienced with a variety of stormwater management solutions, and they’re eager to assist you on your next project. Learn more about our water resources services.

RSC was effectively used for the Reck South Ravine stabilization project in Kenosha County, WI.

RSC was effectively used for the Reck South Ravine stabilization project in Kenosha County, WI.

About the Author



Riley Stone is a civil engineer in the municipal services division at raSmith’s Brookfield office. His experience includes supporting the team on a variety of projects, focusing on stormwater, hydrologic and hydraulic modeling, and municipal roadway efforts. He also provides communities assistance with their MS4 permit requirements.

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