Treatment plant deploys team to clear up water
As Fresno copes with complaints from more than 1,500 homes about discolored water associated with its Northeast Surface Water Treatment Plant, the City Council on Thursday hired two national experts to make sure the same thing doesn’t happen when a new treatment plant opens in the southeast part of the city in 2018.
Vernon Snoeyink, professor emeritus of civil and environmental engineering at the University of Illinois at Urbana-Champaign, and Marc Edwards, a civil and environmental engineering professor at Virginia Tech, will conduct laboratory experiments using samples of galvanized pipes collected from Fresno homes and local surface water from Pine Flat and Millerton lakes.
Edwards’ research team at Virginia Tech was given a $150,000 contract, while Snoeyink and his current affiliate, Water Quality & Treatment Solutions Inc. of Los Angeles, landed a $200,000 contract.
The contracts were approved on a 6-0 vote of the council as part of the meeting’s consent agenda, which is stocked with items deemed noncontroversial and all approved in a single motion. But about 45 minutes later, Councilwoman Esmeralda Soria — who initially voted to adopt the consent items — asked her council colleagues to reconsider the contracts because she had arrived late and was not fully prepared when the vote took place.
Soria said she at least wanted a staff presentation to the council on the necessity for hiring Snoeyink and Edwards. But her motion to reconsider the issue died for lack of a second.
Tommy Esqueda, public works director, said Edwards will perform static lab tests by immersing different samples of pipe for extended periods of time in samples of water with varying adjustments to pH, alkalinity and corrosion- control chemicals.
The combinations of water chemistry that show the least degree of corrosion and release of zinc from the galvanized coating inside the pipes will be applied by Snoeyink in what Esqueda called “pipe loop tests,” in which water is recirculated through the pipes on a continuous basis.
The most promising combination of pH, alkalinity and phosphates will represent the treatment strategy to be used initially at the Southeast Surface Water Treatment Plant. That process will be adjusted as necessary depending on how galvanized plumbing in residents’ homes reacts to the treated water.
“This study will use real-world pipe and realworld water,” Esqueda said. “That’s something that wasn’t done in the 1998 treatability study” conducted for the northeast plant.
Earlier this year, the city broke ground on the new $159 million treatment plant near Armstrong and Olive avenues. When it opens in late 2018, that plant is expected to produce 54 million gallons of water a day, with the ability to expand production to 80 million gallons daily.
Because the Fresno Irrigation District’s Enterprise Canal is the source of water from Millerton and Pine Flat lakes for both plants, the treatment strategy determined by Edwards and Snoeyink will also be employed and monitored at the Northeast Surface Water Treatment Plant.
The northeast plant was built at a cost of about $32 million and opened in mid2004. But within months of starting operation, residents in the area began complaining discoloration in the water. The number of complaints exploded earlier this year after social media posts indicated that problems were more widespread than even many of the affected homeowners had previously believed.
Snoeyink and Edwards were hired by the city earlier this year to help Fresno understand the water chemistry conditions associated with complaints of red, brown or yellowtinged water at homes with galvanized iron plumbing in the area served by the northeast treatment plant.
They independently determined that the marked differences in pH, alkalinity and other characteristics between pumped groundwater and surface water from the treatment plant — as well as daily and seasonal fluctuations in water sources serving individual homes — disrupted rust and mineral scales deposited over years on the inside of galvanized pipes in some homes. That caused discoloration to appear when residents turned on their faucets.
The 1998 study conducted in anticipation of developing the northeast plant had, in fact, predicted the potential for discoloration from galvanized pipes because of the differences between surface water and the pumped groundwater that was previously the sole source of drinking water for the city.
In August, Edwards described the 1998 study as “state of the art for the time.” But, he added, galvanized pipe is one of the most unpredictable plumbing materials in which to assess the potential for corrosion. As a result, Edwards said, the study likely gave the plant’s operators a level of “false confidence” that they could handle whatever the water could dish out.
“I wouldn’t say the report was inherently flawed,” Edwards said. “I think it reflects the naivete of the time that we thought we understood something we really didn’t.”
“We can do all the lab studies in the world and make a hundred wrong predictions,” he added. “But the bottom line is, is this performing satisfactorily in people’s homes, yes or no? And if the answer is no, our science is wrong.”