Sewage plant upgrade should help clear the air |

Sewage plant upgrade should help clear the air

Eileen Joyce
ALL | GrassValleyArchive

The air should smell better at Lake Wildwood when the wind blows from the west, thanks to an upgrade at the Nevada County operated sewage plant that serves the gated community.

For years, sewage sludge – partially treated sewage – has been spread out in concrete beds to dry in the sun at the Lake Wildwood sewage plant on Pleasant Valley Road before being hauled off to a landfill.

Solar sludge drying has advantages, such as using the sun as a power source, but produces odor, attracts flies, and can’t be used during the rainy winter season.

So the sewage plant has installed a centrifugal sludge drier, a machine that uses a 40-horsepower electric motor to spin sewage sludge at 2,500 rpm to squeeze out water, just like a washing machine on spin cycle wrings water out of clothes.

As for odor, “This is zero. This stuff will drop out (of the centrifuge) and look like dirt,” sewage plant operator Wayne Robinson said admiringly Wednesday.

Eventually, workers will construct a new building around the machine and sludge storage area, which should further reduce odor.

The new centrifuge will also allow the sewage plant to scrap a football field-sized pond that holds sewage sludge over the winter when drying beds can’t be used.

“It hasn’t overflowed, but it’s come close,” said plant operator Dan Buchholz. He’s seen the sludge holding pond, located above Deer Creek, filled to the brim during heavy rainfall, such as the New Year’s flood of 1997.

Another advantage of getting rid of the sludge pond is that state officials were going to require the plant to do expensive monitoring to make sure the unlined pond wasn’t affecting groundwater.

Total cost for the project is $450,000, which includes the $254,000 centrifuge, two semi-truck trailers to carry dried sludge, and enclosing the centrifuge in a new building.

The county accumulated the funding from customers’ sewage bills, which haven’t increased in nine years, said Steve Faukner, county wastewater operations supervisor.

“In December, we’ll have a big open house and we’ll actually spin sludge,” Faukner promised.

The upgrades have been planned for a while. They’re not related to an estimated $5 million worth of improvements required under a new state sewage permit that may increase customers’ annual bills from the current $260 to $800, county officials say.

Currently, the Lake Wildwood sewage plant produces about 380 tons a year of dried sewage sludge, which costs $17,000 annually to truck to landfill for disposal.

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