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A Combined Approach to Improve Streams and Protect Sanitary Sewer Assets

Joel McSwain
Hazen and Sawyer
Black Mountain, NC

Authors: Karl, Jarrod J., McSwain, Joel R.

Hazen and Sawyer provides ongoing program management and engineering services to Jefferson County, Alabama’s Environmental Services Department to eliminate sanitary sewer overflows (SSOs) and protect sewer infrastructure along stream channels throughout the County. The Jefferson County sanitary collection system serves 144,000 customers and consists of approximately 3,200 miles of sanitary sewer, 80,200 manholes, and 174 pump stations.  Urbanization in Jefferson County watersheds over the past 50 years has led to widespread erosion of stream channels, exposing and causing failures of sewer mains, service laterals, and manholes. Due to the urbanization and deteriorating stream conditions, it has proved imperative to use a combination of both sanitary sewer infrastructure improvements as well as stream stabilization measures to address and eliminate the recurring SSOs. Improvements include capacity improvements; relocation of sewer pipes and manholes; in-place stabilization of stream banks; or relocation and restoration of the stream channel. 

Hazen has assessed eight watersheds and work on five projects comprising more than 10,000 feet of stream restoration or stabilization where stream erosion has damaged or threatened to damage components of the collection system. Varying levels of stream assessment and design have been used based on individual project goals and objectives to improve channel dimensions, restore floodplain connections, stabilize eroding stream banks, provide grade control, and establish a native plant community for long-term stability. Design challenges included the proximity of existing, exposed sewer infrastructure to the streams; utility relocations; steep slopes; bedrock; highly erodible soils; high velocities and shear stresses; and valley confinement.  

Two case studies will be discussed in the presentation:

  • Tarrant-Huffman Sewer Protection – includes more than 5,000 feet of stream restoration, stream stabilization, sanitary sewer system relocation, and cast-in-place pipe lining along an unnamed tributary to Fivemile Creek in Tarrant, Alabama.

  • East Lawson Road and Sweetwater Circle SSO Abatement – includes 3,000 feet of stream stabilization at 12 separate sites to protect sanitary sewer assets along Dry Creek in Jefferson County.

This presentation will include a discussion of the tools and methods used, why they were selected, benefits and limitations, and the resulting designs.

About Joel McSwain
Joel McSwain is a Senior Principal Scientist with Hazen and Sawyer. He serves as designer and project manager on a variety of stream and stormwater related projects. With 20 years of experience, he provides knowledge and expertise in site assessments, planning, permitting, design, and construction of stream and wetland restoration and asset protection projects.