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How Does CLTWater Respond To A Wastewater Overflow?

First, what is a wastewater overflow? A wastewater overflow, also referred to as an SSO (Sanitary Sewer Overflow), is a release of untreated or partially treated sewage from a municipal sanitary sewer, typically out of a manhole or a broken pipe.

Taken by Cam Coley, employee City of Charlotte, Charlotte Water

While wastewater overflows are nearly inevitable in a system as large as Charlotte’s, we do our best to keep these incidents to a minimum to protect human and environmental health.

How can I tell if there is a wastewater overflow in a creek?

You may notice a gray, milky color or odor. If you do suspect an overflow, call 311 right away and say or select wastewater emergency, and a crew will respond.

What should I do if I see a wastewater spill?

Call 311 or 704-336-7600 and say or select sewer emergency. We will respond 24 hours a day.

How can I help reduce overflows? 

  • Toss in the trash: paper towels, wipes, hair, cotton swabs, feminine products, dental floss, coffee grounds, and excess food. 
  • Toss in the toilet: only toilet paper. 
  • Drain in the sink: soap suds, small amounts of food from the plate, and liquids. 
  • Take to a full-service recycling center: used and expired oils and grease. 

What causes wastewater overflows?

  • Clogs from wipes, paper towels, leftover kitchen grease, oils, or anything other than toilet paper.
  • Pipe failure (tree falls and breaks pipe, stream/creek erosion causing the pipe to fall into the creek)
  • Tree roots attacking and clogging the pipe
  • Damage by nearby construction. (Reminder to always call 811 before you dig.)

How does CLTWater respond?

A rapid response crew will investigate the area and attempt to remove the clog. This work does not impact drinking water quality. Crews may run hydrants to flush the area, lightly apply lime to sanitize, and/or return to investigate other pipes. Residents and their pets are encouraged to avoid contact with the creek during an overflow response.

How does CLTWater respond to a large overflow?

There is a myriad of responses depending on the situation. For example – a tree falls into the creek, washing out the creek bank and undermining the wastewater pipe just behind the creek bank. Crews frequently inspect these areas, but erosion can occur quickly during heavy rain events. Crews will:

  • Create a temporary access road or path if necessary to respond.
  • Install a temporary wastewater pipe to bypass the broken pipe and stop the overflow. The pumps and temporary above-ground pipes are checked several times daily to prevent possible wastewater overflows.
  • Stabilize the creek bank.
  • Construct a barrier / temporary stream bank to protect workers.
  • Remove the broken pipe. 
  • Install the new pipe and test it.
  • Rebuild the stream bank with clean fill material (soil). 
  • Remove temporary pipes and pumps.
  • Remove large spoil piles of dirt.
  • Complete grading/drainage.
  • Plant trees/shrubs and seed/straw the area.
  • Restore the stream bank and revegetate.
  • If the greenway was closed during work, it would be restored and reopened. When greenways are affected, CLTWater works with Mecklenburg County on restoration.

How does CLTWater handle tropical storms or heavy rains and prevent spills?

The underground sanitary sewer pipe network is not designed to handle rain, yet the runoff and flooding from large rains inevitably infiltrate the wastewater pipe network. Overflow basins at the five largest wastewater treatment plants capture and later treat more than 160 million gallons of rainwater mixed with wastewater. These equalization basins (EQ basins) prevent wastewater from overflowing out of manholes in our community.

CLTWater has also added several large wastewater pipes to help reduce the impact of heavy rains. Crews work to prevent rainwater from getting into the sanitary sewer system and are out investigating our system soon after a storm ends.

Additional Resources:

Wastewater treatment plant process

Why does wastewater cost more than water on my bill?

How does CLTWater respond to a wastewater overflow?

What does a growing city mean to wastewater treatment plants?

Is the odor from a wastewater plant or sewer manhole?