February 11, 2005

Ancient water supply may save us from future droughts

By J.D. Hawk

As Sweetwater Authority Engineering Manager Michael Garrod stuck his fingers into a zip-lock bag on Feb. 7, he pinched some clayish mud between his thumb and finger. “Wow, you’re on the leading edge of this report right here,” he said. “It doesn’t look like this will be a usable well. This looks like a clay that you’d make a pot out of,” he said with a slight hint of disappointment.

The clayish soil-sample meant that the groundwater well that Garrod and Sweet-water Authority had hoped for — located on a vacant field near the Chula Vista KOA campgrounds — would not be possible.


Engineer, Michael Garrod holding a soil sample.

But fortunately that’s not the end of the story. Because for Garrod, a 20-year veteran of well-drilling, it’s not about if it can be done, or even when it will be done — it’s just a matter of where it will be done. Garrod knows that there is a an ancient 16,000-year-old underground water supply in the South Bay area that hasn’t been fully tapped. It’s capable of supplying water for the Sweetwater Authority for a minimum of 100 years. And even that is a conservative estimate, according to Garrod, because if the supply is managed correctly the water supply may just last forever.

Currently, groundwater wells supply 177,000 people with 27% of their water (combining both fresh and brackish water-wells). In the next few years, however, that figure will jump up to 40% because of Sweetwater’s plan to add seven more brackish groundwater wells to the nine already in existence.

According to the Sweetwater Authority, the creation of more water wells will increase the reliablity and cost of the water. Groundwater supplies would be drought-resistant, the water wouldn’t have to travel hundreds of miles to arrive here, and it would decrease costs—80% less than new imported water. Though the locations of these groundwater wells aren’t exactly top-secret, Garrod requested that La Prensa not advertise the locations of these wells do to security concerns..

Brackish water is salty water. But, “It’s not saltwater as in ocean, it’s not as salty as the ocean water,” Garrod explained. “The more salt you have to take out, the higher the cost.”

So even though underground brackish water is salty, its less expensive to process than sea water. The Sweetwater Authority had been test-drilling in KOA’s field for the last few weeks in hopes of getting to that 16,000 year-old brackish water supply.


At night, when all lit up, this 50ft water drill could be seen for miles, peaking curiosity from local residents.

With a height of 50 ft., the test-drilling operation may have been mistaken by some Chula Vistans as a new radio tower or some type of mysterious government operation behind the KOA campground. But it was merely Sweetwater taking samples of the earth every 10 ft until it hit the 800-ft. mark. The samples were put into small plastic bags and then analyzed by both Garrod and a Sweetwater geologist. They discerned the dirty differences with almost connoisseur-like expertise. “Some of them are topsoil,” Garrod said while sorting through the labeled dirt bags. “Down at around 110 to 120 feet, we have some nice sands. At 220 ft. you still have sand, but it’s a little bit finer sand and its a different color [lighter]. At 320 ft. its even a lighter sand — it’s heavier but you cans see the grains are a little bit larger.”

Ideally, the soil should be less clay-like, and more sand-like. Sweetwater’s well screen pipes work similar to how a curious child digs a hole near the beach, then holds back the sand while the hole fills with water. “So what we do is put a in sifting screen. What that does is hold back the sand and lets the water come through. Then we put a pump down in the middle of the pipe and pull the water out.”

But despite stories of men surviving the Australian outback for days on end by digging holes in the ground and drinking the water, Garrod doesn’t recommend that you try drinking water from a hole in your back yard. For one, you may have to dig 23 ft. to find any type of water in Chula Vista. Secondly, though the thought of drinking dirt water may be a seductive one, you may get dysentery and die.

The brackish water that Sweetwater pumps up is professionally processed with a series of treatments that would tickle the ears of most mechanical-language junkies — the fiber glass housings holds seven membrane elements, vertical turbine pumps that move water through purifying reverse osmosis membranes in a two-stage array, pressure vessels, a degassifier that among other things increases the water’s ph level, and a holding tank which adds a something else which in turn satisfies the US surface treatment rule.

But at the KOA field, all that is moot. The clay-like soil made the concept economically unfeasible. So now Garrod and the Sweetwater Authority will look for a new area to drill, probably a half-mile further northwest. (The farther you get away from 805, the more likely you get water.)

This “scientific-guess” to drill at KOA cost $100,000. Sure, it may seem like a lot of money, but when it’s understood that establishing a permanent well will cost 1.5 million, and the success rate of engineers correctly picking suitible sites is 80%, it was a not only a necessary gamble, but a justified business expense. “KOA was very amiable to us, they understand the process and we got an agreement with them to drill this hole, it was very nice of them.”

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