In 2010, officials with the City of Daphne discovered highly turbid waters entering D’Olive Creek. The origin of the muddy water was traced to a 20-foot-deep headcut and a severely eroded channel in a tributary of Joe’s Branch within the D’Olive Watershed in Baldwin County, Alabama. Joe’s Branch is included on ADEM’s Section 303(d) list of impaired waters because of siltation and habitat alteration caused by land development. This headcut, the result of excessive stormwater runoff, required immediate attention because it threatened the stability of residences at the adjacent Westminster Village Retirement Community and the heavily traveled U.S. Highway 31.
On behalf of a multi-jurisdictional project team, the Mobile Bay National Estuary Program (MBNEP) secured funding for the project from the Alabama Department of Environmental Management (ADEM) and the Alabama Department of Transportation (ALDOT) to address the problem. Thompson Engineering was selected to design and oversee construction of an innovative and environmentally progressive solution. The project represented the first step in the plan to rehabilitate Joe’s Branch and remove it from the impaired waters list, and was an initial effort to implement management recommendations of the D’Olive Creek Watershed Management Plan prepared by Thompson Engineering for MBNEP in 2010.
The technique used is called a Step Pool Storm Conveyance (SPSC) system. The SPSC system is an aesthetically-pleasing technique that uses a porous sand/woodchip mixture beneath the primary flow channel to retain and filter stormwater during lower flow events. The system’s flow path itself is constructed by a network of rock riffles and pools to stabilize the eroded channel and dissipate energy during higher flow events. The project also included restoration of the degraded wetlands severely impacted by sedimentation from the prior erosion immediately downstream of SPSC rock structures.
The construction of this first-of-its-kind project in Alabama was completed in 2013. Since installation, the SPSC project has:
An educational outreach video, The Restoration of Joe’s Branch, was produced by the MBNEP to introduce the project to municipal leaders and others. It was created not only as an educational tool for this type of project, but also to emphasize the importance of a collaborative approach among various entities to address such problems.