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How to Prepare for and Mitigate Sanitary Sewer Overflows (SSOs)

The Environmental Protection Agency (EPA) estimates that 40,000+ sanitary sewer overflows (SSOs) occur every year. These releases of untreated or partially treated sewage create serious consequences for municipalities:

  • Financial repercussions, including fines, penalties, and private payouts to property owners
  • Environmental damage from dumping raw sewage into waterways, streets, and parks, limiting uses for harvesting, fishing, and recreation
  • Health hazards from contact with sewage
  • Public relations headaches in your own town and those downstream

Cities may never fully eliminate SSOs, but you can take measures to understand causes, prevent occurrences, and respond quickly and effectively to an overflow.

The key is to develop a plan upfront—because in an emergency, the greatest challenge is not knowing what the flows are. With flow data, sizing the bypass is a science—but without it, it’s a guessing game that could have devastating impacts.


Sanitary Sewer Overflow Causes


Almost every sewer system deals with SSOs, although hopefully on an infrequent basis. Here are some of the common causes:

  • Inappropriate materials sent to the sewer, including fats, oil, and grease (the notorious FOG) and household products like flushable wipes
  • Aging infrastructure with cracks and faults that let in tree roots, stormwater, groundwater, and snow melt
  • Incorrect connections to service laterals for sump pumps, and roof downspouts
  • Improper or inadequate maintenance and cleaning
  • Poor pump maintenance and lack of backup power for components like lift stations
  • Undersized sewers and/or pumps
  • Equipment failures and breaks


Sanitary Sewer Overflow Prevention


Municipalities can help prevent SSOs with proper operation and maintenance, adequate system capacity, and good system design and construction. Here are some ways to reduce SSOs:

  • Perform regular sewer system inspection, cleaning, and maintenance
  • Rehabilitate the system and conduct repairs to reduce infiltration and inflow
  • Enlarge or upgrade sewers, pump stations, or sewage treatment plants
  • Educate the public about the hazards of putting FOG or some household products in the system
  • Expand treatment plant capacity


Sanitary Sewer Overflow Response Preparation


Contingency planning is the most effective way to mitigate SSO damage. A crew from a reliable pump provider like Sunbelt Rentals can meet with your municipality’s collection system team at a treatment plant, lift station, or problem spot in the collection system and identify risks. Then, the team can create a contingency plan that is concise, accessible, and agreed upon by both parties.

For example, perhaps a city has issues with a lift station. We can meet and identify the peak expected sewer flow, system head conditions, and emergency bypass connections. Next, we determine the parameters of a temporary pumping system required in the event of a lift station failure, to include temporary pumps, hoses, pipes, fittings, remote monitors, and even telematics. We then put together an itemized list of equipment with a quote, so the municipality knows the exact cost. We provide both an electronic and a hard copy that resides at the lift station.

In an emergency, the operators can pull up the contingency plan, make one phone call, and activate the response. Our team moves into place with pumps and a bypass. The more pre-planning we’ve done, the less impact on the city’s budget and reputation.


Sanitary Sewer Overflow Partners


The collection system of a single municipality is an asset worth millions or even billions of dollars. To maintain system capacity and extend its life, you must also invest in ongoing maintenance and in rehabilitation when necessary.

Rehab costs and actions to correct SSOs depend on the size of your municipality and the type of sewer system you have. All else being equal, however, costs will be highest and ratepayers will pay more in communities that have not put regular preventive maintenance or asset protection programs in place.

To prepare an SSO contingency plan for your municipality, contact our Pump Solutions team. We’re here to answer all of your questions and develop a custom SSO solution for your collection system.