![]() The new preferred approach is often referred to as regenerative stormwater conveyance (RSC). A more thoughtful, cost-effective, and restorative approach to handling urban stormwater flows was clearly needed, and leaders in the County Department of Public Works decided to pursue design solutions that provide a full range of benefits including improved water quality, stable conveyance, increased groundwater recharge, floodplain reconnection, and wetland creation. Based on an inventory of stormwater outfalls, Anne Arundel County, Maryland has concluded that the majority of pipe outfalls, rip-rap and gabion level spreaders and energy dissipation devices used to convey stormwater have failed and resulted in more than $600 million in damage to streams, adjacent wetlands, and steep slopes. The result seen throughout urbanizing watersheds is impaired habitat, excessive erosion and transport of sediment and nutrients to downstream sinks (e.g., ponds, lakes, estuaries, etc.), and compromised infrastructure. Standard energy dissipation (e.g., flared end sections with rip rap or engineered stilling basins) together with overcontrol of discharge, frequently prove to be inadequate to protect against outfall erosion and related receiving stream degradation. Drainage infrastructure, whether it be simply conveyance based or intended for other stormwater management criteria (e.g., detention, channel protection), typically results in the concentration of flows at discrete outfall points.
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