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SSJID plant keeps water flowing during pandemic
A panel with 25,000 spaghetti-like strands of thin, hollow membranes is checked by a worker at the South County Water Treatment Plant.

The pandemic will not stop South San Joaquin Irrigation District from doing what it has for the past 111 years — delivering safe and reliable water.

“Delivering water is central to SSJID’s mission,” noted SSJID General Manager Peter Rietkerk. “In order to keep the water flowing, however we need to have a healthy workforce. The response from our employees to adopt numerous changes in procedures and protocols to respond to COVID-19 outbreak has been heartening. They’ve really stepped up to the challenge of fighting the spread of coronavirus while focusing on delivering water to our customers.”

SSJID provides drinking water for nearly 200,000 people in Manteca, Lathrop, and Tracy. That’s in addition to irrigation water for farms throughout the 72,000 acre district that include ag producers in the Manteca, Ripon, and Escalon areas.

The treatment plant on Dodds Road some 22 miles northeast of Manteca and a half mile from the base of SSJID-owned Woodward Reservoir started delivering treated water in July 2007.

Many mistakenly believe since the water originates form streams high in the Sierra that it is clean. As the water makes its way into the Stanislaus River it picks up all sorts of foreign objects from bacteria to animal droppings.

It is why the first step in the treatment process involves basins where suspended solids are separated from the water.

The most simplistic way to describe how the process works is water initially flowing into the plant goes through a series of baffles that cause the solids — dirt particles and such — to float through the top of a series of open concrete tanks. The water then passes through numerous panels with membranes that snag bacteria and viruses. From there the water is further treated and then sent to a storage tank awaiting its journey westward to faucets in Manteca, Lathrop, and Tracy.


Treatment plant still

cutting edge after 13 years

The treatment plant is still essentially cutting edge even through it is now in its 13th year of operation.

That’s because of the technology incorporated into dozens of panels the water passes through after solids are removed. Each of those panels submerged in the water are jammed with 25,000 spaghetti-like strands of thin hollow fiber membranes.

As the water passes through, the hollow fiber membranes serve as a physical barrier to contaminants. The porous plastic fibers are hollow at the center. The surface is covered with billions of microscopic pores that filter out all known viruses. That allows water to be disinfected and treated with little or no chemicals.

The pores are 0.02 microns. A red blood cell is 0.07 microns.

Microns are equal to one millionth of a meter.

The panels are constantly being removed and cleaned to assure the integrity of the treatment process that has built in redundancies.

The process has the highest rating possible from the California Department of Health Services for water quality.

Computers and humans monitor all aspects of the treatment operations 24/7 year round. Technicians are constantly conducting water tests to verify the accuracy of computer readings and to make adjustments when needed.

It takes water some eight hours once it enters the plant to be treated and sent on its way to reach the nearest faucets in Manteca.

Many people have the misconception bottled water is somehow safer than treated tap water. Bottled water is regulated by the Federal Drug Administration while the Environmental Protection Agency with significantly higher standards regulates municipal water treatment plant.

Making some people’s perception of water safety even more ironic is most bottled water comes municipal water systems such as Windmill Express water kiosks found in shopping centers or from water bottling plants such as the Safeway Select brand that is bottled in Merced.

All the heavy lifting to make water safe to drink is done at treatment plants such as the one SSJID operates.


SSJID water is almost 2,000

times less expensive than

buying it by 16.9 ounce bottles

Then there is the cost factor. A 2017 study by the American Water Works noted that a gallon of bottled water costs $1.22 on average or 300 times what the typical cost is for a gallon of water coming from the tap of an average American home. If bottled water is bought in 16.9 ounce bottles the price per gallon jumps to $7.50 or almost 2,000 times the cost of tap water.

None of the three cities the SSJID treatment plant serves use surface water exclusively as they mix it with well water.

Manteca, in a move to keep costs down, initially set up its system so in a normal year they would not access surface water during winter months. It has since slightly modified that approach using treated water that is of a substantially higher quality to blend with well water to knock down arsenic levels at some wells to meet significantly higher federal standards that went into effect several years ago.

The availability of high quality treated surface water eliminated the need for the city to put in place $1 million plus arsenic treatment plants at various well heads along with the need to spend upward of $400,000 a year replacing filters.

Treatment plant staff also is constantly monitoring 37 miles of transmission pipe that at any given time contains 14 million gallons of water. There are also four pump stations that deliver water to city systems as well as three storage tanks capable of holding a million gallons of water each. The system — saves for the pumps tying into municipal water lines — is all gravity flow.

The SSJID also has in place state-of-the-art microwave communication towers along the pipeline. That means instead of data transmission, security camera feeds, and readings being delayed for as long as six seconds they are instantaneous in real time to further enhance safety.

It takes a lot of power to run the treatment plant. To keep costs as low as possible, the SSJID in July 2008 brought online what was then the largest West Coast tracking solar farm next door to the treatment plant. The Robert O. Schulz Solar Farm generates 1.4 megawatts. In its initial year of operation it wiped out $500,000 in PG&E charges.

It made the SSJID water treatment plant the first in California to have nearly 100 percent of its needed power self-generated. when the second phase was completed in March 2009 by Conergy, it was the world’s first single-axis solar tracking system employing thin-film photovoltaic cells.

The plant is designed for a second phase that can increase capacity at a minimal cost. Ripon is working toward securing water from the second phase by extending a pipeline to the SSJID transmission line. Escalon is also part of the five cities that can use SSJID treated surface water but it has yet to connect with the treatment plant.


To contact Dennis Wyatt, email