The Sweetwater Authority recently began a multiyear water main flushing program using innovative technology to clean all 400 miles of pipeline in its system. It’s part of Sweetwater Authority’s use of the latest technology to deliver a safe, reliable water supply to its South San Diego County customers.

Water main flushing cleans pipeline interiors by sending a rapid flow of water through them. Sweetwater’s program is the first in the region to use a new, innovative technology resulting in less environmental impact.

“We’re committed to providing our customers with high-quality water, ensuring that every drop meets safety standards and protects public health,” said Tish Berge, Sweetwater Authority general manager. “We’re also dedicated to providing the safe, reliable water through the use of best available technology and sustainable practices.”

See the system in action in the following video. A Spanish language version is also available.

New method avoids storm drain discharge

Traditional flushing methods release water from fire hydrants at a high speed in order to flush out naturally occurring sediments accumulating in water pipes over time. Although the sediment itself is harmless, it can eventually affect water color and taste. The water used to clean the pipes often cannot be captured and ends up in the storm drain system.

The bulk of Sweetwater Authority‘s flushing program now eliminates the need to discharge water from fire hydrants during the cleaning process while delivering the same results.

With the closed-loop system and increased controls, crews are able to effectively and thoroughly flush large sections of pipeline with a single setup and staging area. This more efficient setup is less labor-intensive and allows the crew to maintain a safe hub for operations. Photo: Sweetwater Authority

Crews identify all pipes, valves, and fire hydrants located in the area to be flushed. Next, crews connect one end of a hose to a hydrant and the other end of the hose to the no discharge, or NO-DES flushing unit. The process repeats, connecting a second hose to another hydrant and the other end back into the flushing unit, creating a temporary closed loop.

Once the NO-DES flushing unit is turned on and the hydrants are open, water will push through the loop at high pressure, disrupting any accumulated sediment on the inside of the pipes. The water is pushed through a series of sock-like filters, which remove those sediments and return clean, high-quality water back into the system.

Crews closely monitor the filtration system and water quality to determine when flushing of each pipeline segment is complete.

Innovative technology, efficient and environmentally responsible

Additional member water agencies have indicated an interest in the cost-effectiveness of purchasing the NO-DES flushing units for the region and collaborating to create a shared-use program with the technology. Photo: Sweetwater Authority

With the closed-loop system and increased controls, crews are able to effectively and thoroughly flush large sections of pipeline with a single setup and staging area. This more efficient setup is less labor-intensive and allows the crew to maintain a safe hub for operations.

In the National City area 75.8 miles of pipeline was recently flushed. Crews are now completing work in the Bonita area, and then will start work in Chula Vista.

Additional water agencies have indicated an interest in the cost-effectiveness of purchasing the NO-DES flushing units for the region and collaborating to create a shared-use program with the innovative technology.

“Securing a local water supply to ensure the water delivered is of the highest quality through the best technology in our projects and programs helps to maximize value for our customers while also being sustainable,” said Berge.

For more information on the program, go to www.sweetwater.org/flushing.