Now it’s time to “geek out” if you’re a technology lover who wants to understand a little bit more about water. I’ve added a video, so you can hear Rob Leigh, Gene Palop and General Manager, Mark Watton talk about how water recycling works.
Since Otay Water District imports its potable water, there is nothing to actually “see”.
Here’s a fact sheet of their 21 potable water pump stations, 40 potable water reservoirs, their storage capacity and more.
I received a tour specifically of their Ralph W. Chapman Water Recycling Facility. This is where the sewage from your drain goes down through pipes and ends up here where it’s reconverted into clean water. The water is then used for irrigation about five miles away in eastern Chula Vista.
The facility takes about 1.3 million gallons per day of “high quality” sewage (meaning, it comes from residences rather than factories) and within 20 hours turns it into clean water. The water could be drinkable, but customers aren’t ready to psychologically accept water that is recycled from sewage, even as the Pure Water treatment plant uses reverse osmosis to create a product that is actually higher in quality than most imported drinking water or rainwater. But judge for yourself:
First It Goes Down Your Drain
When you sit in your home and turn on the dishwasher, take a shower or wash your hands, everything falls through the drain. The piping in your house is connected to a ‘lateral,’ which is a large pipe underneath your street.
When builders create new developments, they have to work with water districts to decide how water will be pumped into your house and how sewage will be pumped out of your house. Those pipes are laid before you move in. The lateral along your street connects to a main trunk. The sewage then goes to a pump station (if it needs to go over a hill), or gravity will take the sewage down through the pipe and to the facility.
The recycling facility is deliberately located in a low area of the valley in order to maximize on gravity that allows the sewage to flow downward through the pipes.
The operations employees at the Otay Water District have one mantra about this piping: No Spills.
Residents fear and complain about spewing sewage, so the pipes need to remain in good condition. Otay has video cameras that they regularly run through all the pipes. You can see the the pipes on hours and hours of video. (Just make a request! They assure me it’s riveting.)
Otay also has little tractors that run the length of the pipe to check for where they may be deteriorating or leaking. A tractor routinely goes to the ‘hot spots’ to clean fats, oils and grease. Spills usually occur when you’re not paying enough attention to the hot spots.
In the 1970s, old lines regularly needed to be dug up and replaced, which ended up being a multi-million dollar expense. Today, robots can be pulled through the lines to detect wall thickness, saying, deterioration and the overall condition of pipes. Then, crews can go out and dig up only a small swath of the line instead of the entire pipe.
The Salad Bar
“It’s the all-you-can-eat buffet,” they like to joke. Raw sewage first flows into a drum screen, also known as the “headworks”. Here, coarse material is separated from water — and that inorganic and organic material looks (and smells) like week-old salad.
Sewage is about 95% water. This sewage gets sift through a screen. The water passes through the small pores of the screens, while the coarse material gets scrapped off the top.
The coarse stuff then falls through a conveyor and into a compactor where it is washed and then sent off to a landfill.
The water, on the other hand, makes it way into several tanks.
Live, Hungry Bacteria: The Buffet
The sewer water goes into aeration tank. Here, billions of micro-organisms eat the bad bacteria. The process is monitored through sensors and laboratory testing. The water takes about 6-8 hours to run through this aeration tank.
The water then goes through channels and feeds into clarifier basins. Here, sludge settled to the bottom and the clear liquid flows out over weirs at the surface.
After the clarifier basins, the water channels through into a sand basin, where water filters through two feet of sand and one foot of anthracite coal. This helps take out any other materials from the water.
The “brain” of the system are the computers operated from a trailer hub. The whole plant has instrumentation throughout that is hooked up into these Windows based computers. The process is also so highly automated that employees can use the SCADA system on their iPhones and take care of any trouble from wherever they are located.
In the 1970s and 1980s, operators needed to drive around to each of the sites everyday. They would have to check the tank levels, the pumps, etc. Today, the computer technology allows employees to only be at the plant 5 days a week rather than 7. The Otay Water District also has 140 employees now as opposed to the 176 employees they had prior to automation.
Next to the computer hub, Otay Water also houses a laboratory where they not only test the recycled water, but also test potable water. A qualified lab employee goes to specific locations to retrieve water samples throughout the district. She then returns to the lab to check for bacteria, chlorine residual, odor control, etc.
Cuyamaca Water & Wastewater Technology Program provides the degrees for specialists to be able to work at these facilities.
It’s a great crew, so some of you might want to check out certifications.
Address: 2554 Sweetwater Springs Blvd, Spring Valley, CA 91978
Check out the other articles about the Otay Water District: