Combined Sewer Overflows

Successfully protecting the public health and the environment means thoroughly understanding your collection system, the environment in which you operate, and the levels of risk you can accept. From these starting points, a strategy may be developed that preserves the health, safety, and quality of life for the community you serve.

[[The Conner Creek CSO Control Facility]] - the largest CSO facility in the state of Michigan - eliminates up to two billion gallons of untreated discharge to Connor Creek annually and was completed four months ahead of schedule.

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The construction of combined sewers has rapidly extended basic sanitation to countless communities over the past centuries, but combined sewer overflows pose ecological and human health risks that must be mitigated. Even the peak flows brought by relatively frequent storms can cause water quality deterioration and pervasive nuisance conditions such as unpleasant odors and unsightly shoreline deposits of floatable debris.

Climate change and population growth pose additional challenges – meaning potentially more and/or larger storms and certainly more sanitary sewage – so what can utilities do now to ensure that an acceptable level of service is maintained in the future?

Hazen and Sawyer is a leader in developing cost-effective solutions to the toughest CSO challenges, excelling in every facet of CSO planning and control:

• Planning – The initial phase of most CSO projects involves identifying and quantifying CSO impacts, then developing the basic recommendation of a course of action. Hazen and Sawyer has extensive experience in hydraulic and hydrologic modeling and facility planning.
• Design – Hazen and Sawyer has been designing CSO abatement facilities for decades, including some of the largest, most complex systems in the nation, but remains committed to identifying opportunities to maximize use of existing facilities and other cost-effective solutions.
• Construction Management – Where Specs and Drawings turn into operating facilities, Hazen and Sawyer has a proven track record of representing the owner’s interests on site.
• Program Management – Hazen and Sawyer has successfully helped municipalities track multi-faceted capital programs, often under consent decree.

Protecting public health and the environment is a growing challenge. A changing climate may bring more frequent and larger storms, a denser population means more sanitary sewage running through our sewers, and water quality regulations will only tighten. Hazen and Sawyer’s experience and real-world expertise can help you find the solutions to your CSO challenges.

Combined Sewer Overflows @ Hazen and Sawyer

Peter Young, P.E.
Group Leader

Our deep and diverse experience – from preventing billions of gallons of overflow annually with a single facility to developing watershed plans encompassing thousands of miles of pipe – has yielded innovations in both treatment and storage.

We approach each regulatory environment with sophisticated process modeling and pilot studies, determining the most cost-effective way to meet existing regulations, as well as those likely to come in the future.