Salem water crisis: Successful tests as full-scale carbon treatment nears
Set in a clearing near a family of wild turkeys and dense woods at Geren Island Water Treatment Facility, a group of workers futz with the base of a giant funnel as pre-treated and, at least recently, often unsafe-to-drink river water flows nearby.
In less than a week, thousands of pounds per day of super-fine carbon will mix with water in this funnel and jet into the canal, removing harmful algal toxins responsible for Salem's month-long water crisis.
The city of Salem anticipates full-scale implementation of this powder activated carbon treatment early next week, realizing the goal of weeks worth of small scale testing.
'Stress is really high'
Even this week, engineers and scientists have learned lessons they will incorporate into the full-scale procedure.
When full-scale starts, working hours at the facility will stretch to 24/7.
"Stress is really high, but you're working in Eden out here," said Jude Grounds, vice president at Carollo Engineers.
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The current test is of so-called demonstration scale, and utilizes a portion of the treatment facility to treat the water with carbon.
"Small" is relative — already 10 million gallons per day of water treated by powder activated carbon is entering Salem's water supply, about 25 percent of the facility's daily output.
Water at the facility's in-take point this week showed microcystin levels at 1.2 parts per billion — four times the EPA's health advisory limit for vulnerable populations for toxins identified in drinking water.
After the water passed through the powder activated carbon treatment, Grounds said levels of microcystin (a kind of cyanotoxin) were undetectable.
"We know the water getting PAC treated is better than the water coming in," said Brian Martin, Salem city engineer.
The last demonstration-scale testing is expected to wrap up Friday or this weekend.
Advisory still in place
The advisory, which was extended June 10 and remains in place, is for children under 6 years old and vulnerable adults, including those with impaired immune systems, people affected by kidney or liver disease and pregnant or nursing mothers. The city also recommends that pets do not drink the water.
The most recent test results from June 26 show cyanotoxins below the health advisory level, marking eight days since the last time higher levels were detected.
The successful implementation of the carbon absorption treatment is one of the crucial factors that will allow the city to lift the advisory, according to Salem City Manager Steve Powers.
Demonstration scale testing began Monday, made possible because of an assist from the Eugene Water & Electric Board — they donated the system Salem is using to inject powder activated carbon into the water for this test.
"If they hadn't given us that, we wouldn't have started yet," Martin said.
"We owe them a six-pack of Pabst," Grounds added.
Grounds said his email has been full of notes from the water community in Oregon offering equipment or assistance.
Learning process is ongoing
Late Thursday, Grounds and others were calling around for more devices that would allow for better mixing of aluminum sulfate, which they are using alongside polymers to separate carbon from the water before it goes through the traditional filtering process.
"We're going to add a little more juice to our mixing process," Grounds said.
The need for more mixers was one of the lessons learned this week. They also found that the roughing filter — the first of two sand filters post-treatment water will go through — can still function uninhibited even if some of the carbon gets through.
This was one of their early concerns, along with how to keep the power activated carbon suspended in the water and how to settle it out at the end.
Each of those problems also now have solutions.
"It's a mystery," Grounds said. "It's a technical puzzle that's got to be solved."
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