By Reggie Ellis @Reggie_SGN
VISALIA– More than a decade after initiating a plan to turn waste into water, the city of Visalia has made its first delivery of nearly drinkable recycled water.
In December, the city began delivering recycled water through its purple pipeline to the Tulare Irrigation District (TID) following approval by the Department of Drinking Water (DDW). Under an agreement signed in 2013, the city is obligated to deliver 11,000 acre feet of recycled water to TID per year in exchange for 5,500 acre feet of surface water used to recharge the city’s groundwater. Since 2016, the city has received enough surface water from TID to off set one year of groundwater pumping for the entire city.
“A few years ago, CalWater pumped 26,000 acre feet out of the ground and TID has delivered 25,000 acre feet since 2016,” Public works manager Jim Ross told the Visalia City Council at its Feb. 4 meeting.
Groundwater recharge will become increasingly important after 2020 when the Sustainable Groundwater Management Act (SGMA) takes affect requiring water agencies to recharge the groundwater with at least the amount of water it pumped out of the aquifer.
The water was recycled at the city’s Water Reclamation Facility (WRF) which uses an innovative yet elaborate three-step treatment process to remove solid waste and sanitize bacteria from waste water to create nearly potable water.
“Water from your showers, sinks, and toilets finds its way to the water treatment facility,” Ross said. “After it leaves the plant, you can put it in your swimming pool and swim in it.”
The state-of-the-art facility allows the city to use recycled water in ways that were not allowed under its previous system. For decades, the city has used recycled water to irrigate non-consumable crops, such as cotton, as well as pastures for animals not producing milk for human consumption. Under its new system, the city’s recycled water can additionally be used for parks and playgrounds, school yards, cemeteries, landscaping, golf courses, and edible crops.
“It can be used for anything except drinking,” Ross said.
About 11.6 million gallons of waste water per day or 4.2 billion per year finds its way to the WRF. That waste water is then recycled into 13,000 acre feet of almost potable water per year. While 85 percent of the recycled water is already promised to TID the remaining 2,000 acre feet of water per year will be split between Valley Oaks Golf Course, Plaza Park, and city-owned farm land near the faciltiy. The pipeline running to the golf course received DDW approval on Nov. 26, 2018 and deliveries began last month. Ross said the golf course is expected to receive 1,130 acre feet of water per year, enough to irrigate the course for the entire year.
The city is also producing enough recycled water to irrigate landscaping and ball fields at Plaza Park for an entire year. The only hold up is that the pipes that carry water to drinking fountains and sprinklers are the same. In order to get DDW approval, Ross said the city will have to separate the potable water system from the irrigation system. That could take some time as the city will have to install new potable water lines, a project for which there is not a budget at this time. Once permitted, Plaza Park is expected to receive 153 acre feet of water annually.
Just over 700 acre feet per year will be delivered to the city-owned farmland near the Water Reclamation Facility on Avenue 288 southwest of town. The city has been using recycled water to irrigate its row crops for the last 10 years and delivered more than 6,000 acre feet in the last two years. As the transitions from row to nut crops, Ross said the city will be able to meet about 20% of the orchard’s irrigation needs. The city also owns another 322 acres of farmland near the airport which needs about 1,288 acre feet of water per year. Ross said there are not currently plans to deliver water to this property because it is low on the priority list.
As the facility processes more waste water into more recycled water, Ross said the city already has plans to sell recycled water to local farmers. Ross said there are thousands of acres of privately owned farmland surrounding the facility that could potentially use the vast majority of recycled water produced by the Water Reclamation Facility. He said two local farmers have already gone through the permitting process but it is costly and time consuming, so other farmers may not see the benefit.
“TID is the furthest the water goes,” Ross said. “The water can’t go any further than the county boundary.”
After flushing your toilet, the “gray water” enters the headworks at the facility where scrapers remove large pieces of waste and grit that can damage the pumps that move water from one level of treatment to the next.
From there the water is pumped into clarifier beds or large pools where paddles skim the top of the water to remove floating waste, such as fat, grease and oils, and then scraps the bottom for heavier waste. This process is known as primary treatment which also slows down the water to avoid overwhelming the pumps.
Water is then sent through a fine screening process where unsettled solids are removed from the water before heading back to a pooling area known as aeration basins. Large air pumps blow millions of small bubbles into the water to facilitate bacteria that convert ammonia to nitrites and then into nitrogen gas that is released into the atmosphere and removed from the water. The water is then sent to one of the most unique aspects of the facility, the membrane bioreactor (MBR), where it is sucked through millions of straws perforated with holes half the diameter of a human hair. Any remaining solids are squeezed out through these microscopic holes as the water is carried from the secondary treatment to tertiary treatment. Visalia’s facility is the 13th largest MBR plant in the world and the fifth largest in the United States.
After the MBR, water is slowly flowed through a UV Disinfection area where hundreds of ultraviolet bulbs sterilize any micro-organisms that may have survived the primary and secondary treatments and disinfects the water without the use of chlorine, which is hazardous to house in large quantities on site. After the third level of treatment, the water meets all of California’s standards for drinking water.
With a price tag of $152 million, the facility is the largest public works project in the City of Visalia’s history. The facility is the second largest of its kind in the state, fourth largest in the country and the 20th largest in the world.
“You pulled off one of the most sophisticated public works projects we have ever faced,” said Councilmember Greg Collins.