Sweetwater Authority undertakes overdue efforts to flush out its pipelines


For the first time in 11 years, the Sweetwater Authority has started to flush out 400 miles of its pipelines across South County.

Commonly referred to as flushing, because the accumulated sediment is “flushed out,” the system-wide cleanup is a promise the water agency made to its taxpayers last year as it developed a plan for it. tariff increases over the next five years.

This is the first time that the Authority will clean its underground pipes using a water-saving technology known as NO-DES, short for Neutral Output Discharge Elimination System. The process circulates a rapid flow of water through the network, filtering and removing accumulated sediment.

The sediments that often accumulate include minerals commonly found in water, such as iron and manganese. Although sediment is not harmful, it can affect the color, taste and odor of the water.

The Authority’s use of NO-DES is the first of its kind to be authorized in San Diego County.

“This is a flagship program of which we are proud,” said Managing Director Tish Berge.

Flushing is expected to occur within the next three years. For the current fiscal year, the Authority has budgeted $ 234,000 for 12 weeks of flushing services provided by an outside contractor who manages the process.

Work began last month in National City, where groundwater wells are the main source of water. Since groundwater absorbs metals found in soils that affect water color, it is not uncommon for the Authority to receive complaints about the appearance of water from National customers. City.

The last time the Authority conducted a system-wide cleanup was in 2008, although it routinely flushes some pipelines in some pockets of its service area, which includes western Chula Vista and Bonita.

Berge said the Authority has postponed the system-wide flushing, which is typically done every five to eight years, largely because water costs have increased during dry seasons in recent years.

In addition, the Authority did not want to give a bad impression by calling on taxpayers to save water, but to waste large amounts by emptying its pipes, Berge said.

Traditional flushing methods spew water out of hydrants. Gallons of water are wasted.

When the Authority emptied its pipes between 2004 and 2008, it wasted about 50 million gallons of water escaping from fire hydrants and going into storm sewers.

Using NO-DES hardly wastes water. Teams use hoses to connect two nearby fire hydrants to a truck that carries filters and other aspects of the technology. They also close some underground valves to create a loop through which the water flows.

Ultimately, the process captures water that would otherwise flow onto the streets through a fire hydrant, filters the water, and then returns it to the drains through the second hydrant.

The process also comes with other benefits. It has no impact on the water service and allows personnel to test the water flowing through the system and collect data on chlorine levels and turbidity.


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