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Davis plant nearly ready

The Portola Reporter of Portola, California

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It's been a long time coming, but it looks like the Lake Davis Treatment Plant will finally go online in a few weeks.

It took several years to gather the funds, during which the cost of treatment plants went up and up. It took a long time to build.

It took even longer to resolve construction issues. After it was built, it didn't make it past the first cold spell without cracking a few valves. After they were fixed, there were the pipelines to clear -- both the line from Lake Davis to the plant and from the plant to the city's large water storage tank. And another broken valve.

The county finally received that special order valve, six months later, and replaced it two weeks ago (by the time this hits the newsstands). When the line was pressurized, a crack was discovered in the reducer connecting the valve to the pipeline. One more thing.

But, finally, it's the last obstacle, Portola's Public Works Superintendent Todd Roberts says.

"Once the valve's in, we're there. Everything else seems to be working OK. They've been testing it; they have the line filled up. It was just this one valve."

The Lake Davis Treatment Plant, which went offline in 1997 when the Department of Fish and Game cut the line before poisoning the lake to eradicate northern pike, has been subject to controversy and endless negotiations involving the city of Portola, Plumas County Flood Control District, California's Department of Public Health,

Department of Water Resources, Army Corps of Engineers and Grizzly Lake Community Services District.

Although the Department of Fish and Game carefully steered clear of including the treatment plant in any way as mitigation in regard to the Pike Eradication Project (ditto the U.S. Forest Service), it is obvious that the double whammy of two chemical treatments in 10 years played a major role in the treatment plant's slow progress.

It hasn't been easy. And some say, it shouldn't have been built at all. But at the heart of it, the city of Portola has a contract with the State Water Board dating back to 1968 to receive water from Lake Davis, and to pay for that water, whether it is used or not.

One doesn't break a contract with the state lightly. And many local officials, both at the city and county level, add that one doesn't give up water rights -- ever.

What Lake Davis does offer is an assurance of plenty of water. For current residents, it adds clean water to well water with arsenic and lowers those arsenic levels by diluting the well water. The treatment plant assures the city of plenty of water even when Woodbridge is at full build-out.

Right now, the plant is outfitted with two "skids" of filters, which can process 1.5 million gallons of water per day. The plant is already plumbed to add a third "skid," which will increase output to 2.25 million gallons per day and which will not be needed until the city begins to grow once again.

The treatment plant itself is a massive structure with two outside concrete basins to hold incoming water and allow it to settle out silt and larger objects. Also outside the main building, a large tube filled with charcoal provides a final filtering to water leaving the plant. Behind the charcoal filter is the 250,000 water tank for finished water on its way down the pipeline.

But the main work of treating the water happens inside the main building.

Mike Achter is the city's water treatment plant operator and he spends most of his time at the plant.

"Mike has been in on every meeting since the beginning of construction. He's been through the whole process," Roberts said as he introduced him.

Before turning the treatment plant tour over to Achter, Roberts said, "You've probably gotten the impression that the treatment plant runs itself, but in fact, there's a lot of moving parts."

Achter added, "It does run itself, except when it hiccups. And it hiccups a lot."

He pointed out one of the problems: a small screen in a valve serving a pre-filter that clogs up frequently, causing Achter to have to shut things down while he cleans it.

There were a number of deficiencies during the construction stage but Achter said that the Army Corps of Engineers took care of most of them. This particular problem was a design deficiency that could not be overcome.

A pre-filter cleans out crawdads and small catfish and other things down to 100 microns. From there, the water enters the banks of filters, taking out particles down to 1 micron.

That might be enough, but if more is needed, the water can be put through a charcoal filter outside the plant before heading down the hill to users.

Although the plant can run automatically, there are any number of adjustments that Achter can make to assure citizens the best tasting water possible.

Roberts added that, depending upon the condition of the lake, whether it has recently "turned" or if water is coming through dirtier than usual, the operator can decide to pull water from a different strata in the lake. There are three levels that the city can draw from, but changes must be coordinated with the Department of Water Resources.

The last piece of the puzzle, the reducer, is common and easy to get. Roberts expects that it will be installed within a couple of weeks.

"As soon as this is done, we're going to start running water," he said.

This comes as a surprise, since the city declared that it would not be using Lake Davis water during winter months, only during high volume summer months.

Roberts said that it was necessary to keep chlorine in the filter "pods" and to circulate water at all times.

"We might as well send some of it down the pipeline and keep it clean and flowing. We intend to use it in the winter. We have to. We're paying for the water anyway; we might as well use it."

Original Publication Date: January 18, 2012



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