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Kept locked up behind fortified gates, the Calexico Water Treatment Facility at 545 Pierce Ave. on the west side of the city stands protected against any possible threats, a standard for municipal water plants in the United States since Sept. 11, 2001. The plant and its water distribution system will undergo nearly $10 million in capital upgrades during fiscal 2020-2021, ending June 30. | CAMILO GARCIA JR. PHOTO

Calexico Clears Up TTHM Problem at Water Plant Amid $10M Year

CALEXICO — Through June 30, the city of Calexico has undertaken or has still planned a total of nearly $10 million in major work to its water treatment plant and water distribution network to replace or repair aging pieces of a core system built in 1949, then rebuilt three times since.

Most recently, the Public Works Department finished the second phase of upgrades on Jan. 30 to its Eastside Water Reservoir, installing a more than $212,000 aeration system that Calexico’s water systems supervisor, Jose Saldaña, said will put an end to the city’s violations of total trihalomethanes, or TTHMs.

The announcement was made during an informative and fascinating presentation about the city’s water system by Saldaña and Public Works Manager Liliana Falomir during a Calexico City Council meeting on Feb. 3.

Municipal water customers around Imperial County — around the United States, in fact — might recognize those scary letters, “TTHM”; they are the big red-flag warning that appear in notices of violations delivered with many water bills when water-treatment plant operators test for the presence of the potentially cancer-causing organic compound in drinking water stores.

A satellite image of the Calexico Water Treatment Facility at 545 Piece Ave. shows the plant’s 6 million- and 4 million-gallon storage tanks. | GOOGLE EARTH IMAGE

Water-quality regulators require cities to report elevated levels to customers when those levels become higher than acceptable state or federal drinking-water standards, and Calexico ran into that issue — like a handful of Valley cities in recent years — sourced to high readings at a water sampling station located at Sapphire Street and Cantu Avenue on the east side of the city.

With well over 170,000 municipal water systems in the United States, disinfecting billions upon billions of gallons of raw water, an industry standard is to use some form of chlorine to kill water-borne diseases, and some 84 percent of all large water-treatment systems (serving 10,000 people or more) were using the element in 2000, according to the American Water Works Association.

However, with that widespread use comes the threat of chlorination byproducts like trihalomethanes, which are the result of a reaction between the chlorine and natural organic matter in the water that is exacerbated by warm weather and still conditions, hence the need for enhanced filtration and aeration, like the system purchased by Calexico and installed on the storage tank on the eastside.

Saldaña said the city is guaranteed 30 percent removal of TTHM levels, which will return the city to within state standards and end the notices of violations that appeared in November 2019 and January and July 2020.

A list of capital improvement projects for the Calexico Water Treatment Facility are shown for fiscal 2020-2021 (July 1, 2020, through June 30, 2021). | SLIDE IS COURTESY OF CALEXICO PUBLIC WORKS DEPARTMENT

Meanwhile, the city’s water-treatment system and its network of distribution lines are getting much love in fiscal 2020-2021, with $9.385 million in upgrades, which include big-ticket items like a $2 million water pipeline replacement, and a $5.2 million new clarifier and filtration system.

Next up, Saldaña and Falomir explained, is the switch from volatile and potentially hazardous chlorine gas in the treatment process to a more stable and “better for the environment,” Saldaña said, liquid chlorine, also called “hyprochlorine.”

That changeover will cost about $400,000, and Falomir said on Feb. 3 that a related agenda item will come before the City Council at an upcoming meeting.

In taking the council and the public through the city system, Falomir explained the plant at 545 Pierce Ave. was first built in 1949, with major overhauls in 1968, 1986, and 2000. The current capacity of the system can treat 16 million gallons of water at a time, with the storage capacity to hold that 16 million gallons of treated water and hold another 25 million gallons of raw water at its tank on V.V. Williams Avenue.

Falomir said Calexico uses a maximum of 9 million gallons of treated water a day and a max of 2.2 billion gallons a year.

On the distribution end, she said there are 106 miles of water lines in the city and five distribution pump stations, four large pumps each capable of moving 4,000 gallons per minute and one smaller pump that can move 1,000 gallons a minute.

Saldaña briefly explained the process the city uses to clean the raw Colorado River water the city buys in bulk from the Imperial Irrigation District, to the point it reaches the tap of Calexico residents’ homes.

In short, it is a process that involves moving large volumes across the city to the Pierce Avenue plant, where it goes through clarification, filtration, and disinfection processes before residing in one of three storage tanks (two 6 million-gallon tanks, including the eastside tank, and one 4 million-gallon tank), and onto the distribution network.

The process to treat water in the city of Calexico is shown. | SLIDE IS COURTESY OF CALEXICO PUBLIC WORKS DEPARTMENT
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