Threading the Needle: Routing a Large Diameter Sewer Main through a Densely Urbanized Corridor

The San Antonio Water System (SAWS) serves more than 1.6 million people and over 411,000 sanitary sewer customers in the Greater San Antonio area and it continues to experience rapid growth. In July 2013, SAWS approved a settlement agreement with the U.S. Environmental Protection Agency (EPA) and is currently under a Federal Consent Decree (CD) to reduce sanitary sewer overflows (SSO) over a ten (10) year period. Through this CD, SAWS committed to performing system wide condition and capacity assessments of their sanitary sewer collection system. This paper will describe how Freese and Nichols, Inc. (FNI) analyzed alignment alternatives for approximately 5.2 miles of large diameter, undersized sewer main located in an urban corridor of South San Antonio, dubbed the ‘Main Stem’, that would provide a robust, improved conveyance system with a focus on minimizing impacts to the community.