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Wastewater among state’s cleanest

Manteca treatment plant earns high marks

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Wastewater among state’s cleanest

Manteca's wastewater treatment plant is considered one of the best in California.

HIME ROMERO/The Bulletin


POSTED February 22, 2010 1:13 a.m.

Manteca’s wastewater treatment plant seven years ago was under intense scrutiny from state water quality control inspectors.

The aging plant used a process that no longer addressed tougher water quality control standards for the treatment of wastewater. The plant regularly failed new state imposed tests involving ammonia.

Today, it is an entirely different story. The wastewater treatment plant just north of the Big League Dreams sports complex now employs a state-of-the-art cleansing process using bacteria and ultraviolet light that is part of a $61.3 million expansion, upgrade and retrofit that started construction in December of 2003.

It is so effective that it is turning out water that is essentially safe enough to process as drinking water once it is returned to the San Joaquin River. Because of that, the Manteca plant is being nominated by various professional organizations as one of California’s best wastewater treatment plants.

It is in the running for the California Water Environment Association’s plant of the year. It also has received an EnerNOC Energy Conservation Award and an American Council of Engineering Companies Engineering Excellence Award.

The treated effluent meets stringent state quality standards so it doesn’t harm fish, fowl or humans that may use the river.

Effluent goes through a simple process employing high tech with built in redundancy and back-up for environmental protection to treat an average of 9.87 million gallons of wastewater a day.

The treatment plant has effectively blended into the background thanks to the upgrades that provide water that is essentially clean enough to drink. The covering of various initial treatment tanks has also made the plant so unobtrusive that the 300,000 plus visitors to the Big League Dreams sports complex can’t smell a thing even though they are downwind. The process has been upgraded to such a point that the firm building a small business park adjacent to the plant site has no reservations about the location.

The use of expensive chemicals – specifically chlorine - has been greatly reduced by installing state-of-the-art ultraviolet light channels to kill off disease causing organisms. There are 16 modular banks of UV lights that contain 2,240 separate UV light tubes.

The process is much more effective as there is a 100 percent kill rate of bacteria that cause diseases. The trade-off, though, is higher power costs that push the energy tab for running the plant past $1.2 million year.

Manteca is working to reduce that bill with the goal of making the plant self-sufficient in terms of electricity by employing solar panels and a cogeneration unit to generate power by burning methane gas. They are working with energy experts at the South San Joaquin Irrigation District to find ways to further reduce the municipal power bill for the treatment plant.

City staff is also working on plans to divert treated wastewater from being returned to the river to instead help irrigate everything from landscaping to parks. It would cut costs in two ways – by helping reduce the use of expensive treated drinking water to irrigate landscaping and to avoid possible future state-mandated upgrades in treating water returned to the river including more extensive removal of salts.

Manteca currently uses agricultural wash water sent to the treatment plant site via a purple pipe from Eckert’s Cold Storage on Moffat Boulevard.

There are some 240 acres of corn used as silage for dairy cattle that is irrigated with the Eckert’s water.

In addition, the city is working with the Central Valley Regional Water Quality Control Board to have contractors fill water trucks at purple pipe hydrants near the entrance of the treatment plant off Yosemite Avenue. That way when dust control is needed during construction, it can come from recycle water and not from fire hydrants on the streets. That could save enough water during construction season to serve up to 300 households a day.

Manteca’s plant operators also “store” effluent to allow as much of it to be treated a possible during off-peak hours for electricity use. In doing so, they have managed to cut Manteca’s power bills.


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