Albany GA’s decision analysis systems approach to eliminate combined sewer overflows

Joseph Threadcraft, K. Bruce Maples, Stacey Rowe, Jeffrey Hughes, Brian Jackson, Nandana Perera, Hailiang Shen and Mike Gregory


Combined sewer systems use a single pipe to receive and transport wastewater and stormwater. During heavy rain events, the volume of stormwater entering the pipe exceeds infrastructure capacity and results in the discharge of untreated flows to receiving waters. The City of Albany is in southwest Georgia and has sanitary sewer systems that date to the early 1900s. These systems were developed using the combined sewer methodology. The overflows that result from this design negatively impacts the receiving waters of the Flint River. This problem is not unique to the City of Albany. The U.S. Environmental Protection Agency has indicated that nearly 860 municipalities across the U.S. have combined sewer systems.

One of the ways that regulatory agencies can achieve compliance with the Clean Water Act is through the issuance and enforcement of permits. The City of Albany recently received the reissuance of its two National Pollutant Discharge Elimination System permits. The decision analysis systems approach used by the City of Albany to achieve permit compliance provides a model for consideration by other municipalities. They developed a comprehensive capital improvement program in advance of the reissuance of the final permits. After the permit reissuance, they completed a peer review of all documents. The city leaders approved the reduction of localized flooding for 10-year storm events within the combined sewer overflow basins. PCSWMM software was used during the development of the capital improvement program and in the subsequent validation of the preliminary designs. Some noted permit requirements include an 85% minimum capture rate, implementation of best available technology, and achieving technology based effluent limitations. Achieving these milestones will result in the following substantive benefits.

  1. Improve the health and quality of life for residents and downstream users of the Flint River
  2. Compliance with the Clean Water Act to meet water quality standards
  3. Provide a positive return on investment to the environment

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