HUMBOLDT — Unless you saw it before treatment, you’d never know the clear sparkling water that flows from Humboldt taps was once a murky green. The turbid Neosho River is the source for Humboldt’s drinking supply, said water plant superintendent John Hodgden, leading a tour of the plant last Thursday.
The plant intakes 1000 gallons a minute, and processes the 240,000-350,000 gallons of water used daily in Humboldt.
It has the capability to purify 1.4 million gallons per day should the town ever grow, he said.
“If we actually pumped 1.4 million gallons per day, (the pumps) would run 24/7. Right now, at the capacity of we’re doing, they run one to one and a half hours on, then three to four hours off.”
The system is regulated by float switches, similar to an on-demand system, he said.
In addition, the plant has 575,000 gallons of purified water stored: “Almost two days worth,” said Hodgden.
That storage came in handy during the 2007 flood.
“The water got into the bottom of our intake structure,” Hodgden said, but didn’t cause disruption of the treatment system. “But the water quality was really poor,” he added. “It had a funny diesel smell to it and a sheen.”
Hodgden shut off intake to the plant and used stored water to keep Humboldt supplied during the time it took for the river to clear.
Stored water was credited with averting another mishap half a decade before the flood.
“In January of 2002, an ice storm decommissioned the plant for 2 1/2 days,” City Administrator Larry Tucker said. “Enough water was stored to keep the lines full.”
“We were lucky,” Hodgden said. If the lines had gone dry, much effort — and expense — would have been required to resupply Humboldt with drinking water.
Two generators were added in 2008, said Tucker. One, a 40 kilowatt, stands near the pump tower that draws raw river water into the plant’s pipes. The other, a 60 kilowatt, stands next to the plant itself. Both are built up off the ground on concrete pads “in case of flood,” Hodgden said.
The generators automatically monitor power into the plant and kick on if needed, Tucker said. They are automatically tested each week and have automatic alarms that go off should anything go wrong.
When not in use, the generators sit sentinel while water is piped 45 feet up from the river’s bottom to the pump valves in the tower.
After intake, the water goes to a rapid mix site.
“We feed our primary coagulant here,” Hodgden said. The coagulant is a cationic aluminum polymer that “binds with the dirt” in the water, he said. The particles settle at the bottom of the large tanks.
Cleaner water at the top is siphoned into a half-dozen weirs that span each tank.
“Every 15 minutes the sludge is sucked out of each basin,” Hodgden said, “and is pumped into two holding ponds.
“Once every other year we clean those ponds out,” Hodgden said, “and the sludge is hauled to the landfill.”
Beside the initial pumping, the system is a simple gravity feed settlement and filter works, Hodgden said.
“We have screens on our pumps at the intake, so we don’t get any large animals” into the system, Hodgden said, “but we do have fish eggs that come through, so we have fish in all these tanks,” he said, pointing to the large concrete pools in the treatment plant’s yard.
To combat odors and other impurities in the water, 50 pounds of powdered activated carbon is added daily to the fluid.
“We feed that in, it takes out all the fishy smell” said Hodgden. “If it gets bad, we’ll feed more. Carbon acts like a sponge — it grabs anything that’s in the water and pulls it out.”
The carbon also blocks sunlight, so algae that accumulates in the tanks dies out and is strained out in the settlement process.
“The final basin provides us with more retention time,” for such settling, Hodgden said.
After the water has been through the pools, it is piped into the treatment plant for further purification. The water is tested for residual copper, lead, chlorine, zinc and pH, and is further filtered.
“It travels through three layers of standard media: Anthracite, sand and gravel,” Hodgden said.
Plant personnel are on hand round the clock. Testing is done every shift. “Whenever the pump’s running, we take samples,” Hodgden said.
“We can backwash any part of the system to the ponds if any contaminant gets in,” Hodgden said.
After the water has been thoroughly filtered, chlorine is added.
Ammonium sulfate is added with the chlorine “to keep it residual in our system,” Hodgden said. Otherwise, chlorine, which is a gas, would dissipate out of the lines before it reached the taps. Chlorine levels are maintained at 2 to 4 PPM, Hodgden said.
Fluoride will be soon be added to the water along with the chlorine. While the Neosho’s water naturally contains 0.14 PPM fluoride, Hodgden said, levels must be increased to 0.7 to 1.2 PPM to protect tooth enamel.
“We’ll test twice per shift to see what’s coming out,” Hodgden said. “If (ambient) fluoride goes up, we’ll be able to adjust our input accordingly.” Faucet filters will take out some of the added fluoride, he added.
Tucker said the city has received a $400,000 Community Development Block Grant to replace eroded large and medium sized delivery lines throughout the city. The old lines are primarily cast iron, and fall victim to dissolved minerals in the region’s water. Of primary concern is a major delivery line from the plant to the water tower on 10th Street.
“We’ll be replacing most of these old lines with polymer plastic,” Tucker said. “Many of them are over 100 years old,” he added. “We’ll be replacing a number of smaller lines, too.”
The updates “will greatly reduce our maintenance costs and ensure infrastructure for the next 100 years,” Tucker said. “We want to make this place a better town for our children and grandchildren.”
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