Sean C. Morgan
The recent location and repair of a major leak appears to have saved the city a lot of water, but exactly how much is yet to be determined.
The Sweet Home Water Treatment Plant produced 242,000 fewer gallons per day in the seven days following a major leak repair than it did in the seven days prior to the leak repair, according to the city Public Works Department.
Public Works shut down a pipe that had been leaking directly into a stream crossing 9th Avenue north of Nandina Street on April 16. After shutting down the pipe, Public Works measured a reduction in the stream flow of roughly 343,000.
That amount accounts for nearly 80 percent of water lost in the city’s water distribution system. For the past couple of years, the city has been unable to account for approximately 40 percent of the water produced at the Water Treatment Plant.
That water is simply never measured going through a meter. The losses are likely through leaks and through old water meter, with worn parts that are incapable of measuring all of the water flowing through the meter.
In the seven days prior to the leak repair, the city averaged a production of 1.135 million gallons, said Utilities Manager Steven Haney. In the seven days following the repair, it averaged a production of 893,000 gallons, a difference of 242,000 gallons per day, which is lower than the flow reduction measured in the stream.
Public Works Director Greg Springman said the stream measurement provides a ballpark estimate of the stream flow and is not the most accurate method.
Haney said that the ebb and flow of water to and from the reservoirs may also impact production numbers, so the 242,000 may not reflect the entire impact of the leak.
For that, the city will need to look at longer averages.
The city can use month-long production averages, he said, by comparing relative production directly to water loss, regardless of whether people start watering their lawns and gardens, which also runs out of the system through water meters.
A month should be long enough to account for fluctuations in the water reservoirs, Haney said. The city can account for water stored in the reservoirs and what goes through meters.
It will take a month or two to get a set of average production and usage. Whether it takes a month or two depends on when the meters were read in relation to the leak repair, and he didn’t know when that was Friday evening.
The more data the city has, the better it can evaluate the impact of the leak on the water system.
“The gist is we’re seeing between 200,000 and 400,000 gallons,” he said. “It’s significant.”
At 200,000 gallons per day, the leak would account for nearly half of the lost water.
Haney is optimistic about the distribution system as a whole.
“We have minimal known leaks,” he said. “We fix them as we find them.”
After this leak repair, he thinks a substantial amount of water is likely lost to old meters and “seeping” leaks, noting that old meters may read 10 gallons while 12 gallons actually flow through them.
“I’m really hopeful we might be in pretty good shape,” he said.
Not only does fixing this leak reduce lost water, Haney said, but “it should help with pressure problems throughout the city as well.”
To understand why that is, he likened it to a garden hose with a large hole. Close the hole, and the pressure in the hose will rise.
With this leak, the city had a garden hose with a hole spilling out water all day, every day, he said. One member of the staff near the south edge of the city’s water system believes that he perceived a difference in water pressure at home.
“It’s a benefit that isn’t as easily quantifiable,” Haney said, although the city has acquired but not yet installed flow-monitoring equipment that can answer questions like changes in water pressure.