Sweetwater Authority modernizes a southern California water system through methodical maintenance and repairs, and innovative water sourcing.
Some water districts are blessed with an abundant supply of clean water. The Sweetwater Authority isn’t one of them.
For four decades, Sweetwater Authority has been bringing a water system begun more than a century ago into modern, safe practices while upgrading its infrastructure. One of its greatest successes is drawing pure, clean drinking water from a supply that’s anything but.
Sweetwater Authority did that by thinking ahead and taking a well-timed chance on technology, says Jim Smyth, general manager. The result is enabling the authority to depend less on outside purchased water than it used to, at a savings to ratepayers and in a state that until recently labored under drought.
This summer, that supplemental source of water is set to double in size — further reducing the authority’s dependence on outside suppliers.
The Sweetwater Authority’s origins reach back to the settling of the San Diego area. Today, the authority provides water to about 189,000 people over a 32-square-mile service area that includes National City, Bonita, and western and central Chula Vista, California — three adjacent communities immediately south of San Diego.
It was established 40 years ago, but Smyth traces its history back more than a century earlier, when the area’s water system was created by brothers Frank, Warren and Levi Kimball, who moved from out east to develop the area and established the Kimball Brothers Water Company.
“They knew they needed two things to get people to come here: the water and the railroad,” Smyth says. To meet that first requirement they built the Sweetwater Dam in 1888 on the Sweetwater River. It was the largest masonry arch dam in the country at the time.
The water company’s original infrastructure consisted of 57 miles of various steel pipelines ranging from 4 to 36 inches in diameter. That included 10 miles of 24-inch riveted steel pipe extending into National City. In the decades that followed, the area grew, and when the U.S. Navy made San Diego the home port for the Pacific Fleet during World War II, population and development soared, along with the demand for water.
For 110 years, water for National City, Bonita and Chula Vista was provided by a patchwork of about a dozen private water companies. Originally established in 1972 to finance the public acquisition of the system, Sweetwater Authority took over the operations in 1977 under an amended joint powers agreement between National City and the South Bay Irrigation District.
Decades of rebuilding
Like a new college graduate facing a six-figure college debt, the authority was born with a huge financial burden. The previous private owners had no consistent maintenance practices and no plans for the future.
“In 1977 when we took over, the system was in very, very great disrepair,” Smyth says. “There were nearly 200 leaks a year. We just inherited a system that had a very high maintenance need.”
For 40 years, Sweetwater Authority has been making up for previous neglect. The new authority drew up a master plan for replacing its 90 miles of aging metallic and undesigned pipeline. It
targeted 8 miles of the remaining 1888 riveted steel pipe that had once been the system’s mainstay. The pipe was still in good shape, but the rivets wore out.
The replacement project included 45 miles of cast iron pipe put in between World Wars I and II. The highly corrosive local soil took its toll on the material.
“We’ve replaced all the cast iron over time, but it took about 30 years to do it because of the cost,” Smyth says.
The remaining 265 miles of pipe in the original system is made from asbestos cement, most of it installed between 1950 and 1980. It was not included in the original replacement program given the material’s track record for reliability and its 100-year rating. The authority is now developing a follow-up replacement priority program to identify asbestos cement pipe for replacement.
Today, the entire system has grown to 388 miles of pipeline, and leaks are down to fewer than 10 per year. The authority uses PVC for 16-inch or smaller replacement lines. New pipelines 24 inches or larger are steel, and pipe in the 16- to 24-inch range is a mix of PVC and steel.
Steel pipe is coated on the inside with a cement lining per AWWA waterline standards and wound around the outside with vinyl tape. Ductile iron is rejected because of its vulnerability to corrosion.
Economy and innovation
The Sweetwater Authority draws water from three homegrown freshwater sources: two deep freshwater wells in National City, the Sweetwater Reservoir, and an auxiliary reservoir further upstream.
The reservoirs store water from the Sweetwater River and help capture local runoff. Like many rivers and creeks in California, the river dries up when there’s no precipitation, so the authority must purchase water from the San Diego County Water Authority, which gets its water mainly from the Colorado River and Northern California.
Long before California’s five-year drought, which only ended in early 2017 with a series of significant storms, water officials throughout the state have been prospecting for new sources.
In the early 1990s, the Sweetwater Authority hired the U.S. Geological Service to drill a series of pilot holes in Chula Vista to a depth of 1,000 feet. They found groundwater 150 to 200 feet below the surface.
Carbon dating shows that water supply to be nearly 20,000 years old.
“It’s brackish,” Smyth says. “It’s not drinking water, it’s not seawater, but it’s a little bit in between. You don’t want to drink it — you just don’t.”
EPA standards require no more than 500 parts per million of impurities in drinking water. By comparison, water from the ocean typically contains about 33,000 ppm — mostly salt. This ancient underground cache of water has about 6,000 ppm — a chalky mix of salt and other minerals.
The condition of that water didn’t deter the authority’s engineering director at the time, Richard Reynolds. Reynolds suggested a workaround: reverse osmosis — passing the water through a special membrane that removes ions, certain molecules and larger particles.
The authority’s directors agreed to the plan and subsequently promoted Reynolds to general manager. Smyth succeeded him as engineering director, charged with carrying the idea forward.
After nearly a decade of planning and subsequent construction, the new facility for treating this underground water supply opened in 1999.
Reverse osmosis technology is some 50 years old, Smyth says, “but it’s expensive.”
When Reynolds first broached the idea of using it to treat the brackish groundwater, calculations showed it would cost more per acre-foot of liquid to extract and treat it than it would to buy the same amount from the San Diego Water Authority. But Sweetwater Authority projected that in time the price points would pass each other, making the underground supply cheaper in the long run.
“We took that risk and it paid off,” Smyth says.
The Richard A. Reynolds Groundwater Desalination Facility opened with a production capacity of 4 mgd. A new $42 million expansion will bring the total reverse osmosis treatment capacity to 10 mgd once it comes online this year. The project is 75 percent funded through state and federal funds. The remaining $10.7 million cost is being split 50-50 with the city of San Diego, which will get half of the new water production.
The expansion required additional treatment equipment as well as five additional wells and 19,700 feet of new pipelines, but the plant building was already large enough for the added capacity. The wells themselves cost about $1.5 million each. “We have to use stainless steel well casings, because the brackish water is very corrosive,” Smyth explains.
This alternative groundwater supply is expected to make a significant contribution to the authority’s water inventory.
Demand on the Sweetwater Authority system ranges from 10 to 15 mgd in the winter to 30 to 35 mgd in the summer. In recent years, the authority has depended on water purchased from the San Diego Water Authority to meet that demand.
The two National City freshwater wells to which the authority has access produce only 2 mgd. Meanwhile the reservoir can’t be counted on during extended dry spells: “The only way to get water in it is by rainfall,” Smyth notes. “This groundwater was an added benefit — it’s drought-proof.”
The authority avoids over-pumping from the underground supply. California’s drought-stricken agricultural Central Valley has seen firsthand the dangers, as natural underground water reservoirs run dry and give way, causing the landscape to sink in places. Authority engineers are watching their own system’s use closely and consulting with the U.S. Geological Survey to calibrate how much water they should draw. “We don’t want to pump more than what’s being replenished,” Smyth says.
Safety and maintenance
Smyth, who joined the Sweetwater Authority in 1980, just three years after its founding, says concern for safety has been built into the agency’s culture from the start.
A safety committee made up of employees meets regularly to analyze accidents and other safety problems. It sets goals to reduce or eliminate chronic problems such as ergonomic strains as well as reduce hazards that could lead to acute injuries.
Changing practices enabled by new technology have helped improve safety — such as using saws for cutting pavement to install new pipe instead of making workers operate body-pounding jackhammers. “It may cost you on the equipment, but it’s going to save you on the workers’ compensation side,” Smyth says.
The authority has also been refining its maintenance practices, employing asset management strategies to schedule maintenance.
The recently concluded drought has added to the authority’s challenges, reducing revenue from water sales and therefore cutting into resources available for initiatives. “It’s getting harder for public agencies,” Smyth says. “We’ve got to do more with less.”
With attention to details ranging from safety to maintenance, to its developing of innovative sources for water, though, Sweetwater Authority appears to have found a way not just to do more with less — but make the most of it.
Recognition from its regional peers is evidence of the Sweetwater Authority’s performance as a water utility.
In 2015, the California-Nevada section of the American Water Works Association gave the authority an award for Outstanding Service to the Industry. The award was in recognition of the support the authority gave to the work of its program director, Sue Mosburg, up to and during her time as chair of the California-Nevada section.
Recognition internally is a significant part of the authority’s approach as well.
And because safety is a keyword, the authority recognizes it through two separate in-house awards.
“We actually make a big deal here by celebrating once a year and giving a couple of safety awards,” says Jim Smyth, the authority’s general manager. The “Big Al” safety award, named for former Sweetwater Authority general manager Al Sorensen, and the “Rubey” award both recognize employees for recommendations that enhance worker safety on the job.
Sweetwater Authority’s practice of promoting safety has brought the agency regional recognition as well. In 2016, the authority received the AWWA California-Nevada section’s Larry C. Larson Safety Award for its commitment to employee health and safety.