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City investing in low-tech well

A natural aquifer allows water storage without a tower.
Thursday, October 23, 2003 | 12:00 a.m. CDT; updated 6:28 a.m. CDT, Sunday, July 20, 2008

Columbia is prepared to spend less than 1 percent of a $28.3 million bond issue on the Nov. 4 ballot on bargain technology to stash 31 million gallons of treated water deep in an underground well.

The process, Aquifer Storage and Recovery, works sort of like an underground water tower. City officials say they love it. For one, they said, it’s clean, safe and environmentally sound. For another, installing an ASR system can be less expensive than painting a water tower, let alone building one.

“It’s the cheapest storage around,” said Jim Vandike, chief engineer of the groundwater section at the Missouri Department of Natural Resources.

Columbia already has one ASR well — the only one in the state — which was built in 2000.

About $250,000 from the $28.3 million Proposition 2 bond issue would be used to outfit another well for storage before 2005, said Floyd Turner, head of water operations for Columbia Water and Light.

Implementing ASR is simple, Vandike said, because it relies on a resource Columbia already has: a 500-million-year-old aquifer that acts like a giant bedrock sponge.

Instead of pumping treated water upward into a multimillion dollar water tower, the city simply lets it cascade into a narrow hole deeper than the Empire State Building is tall. The cost? About $500,000 total. The city already has $250,000 set aside from an earlier bond.

The process resurrects wells that used to anchor the city’s water supply. In 1972, when the city began tapping into the Missouri River bottoms near McBaine, the wells became virtually obsolete.

When it’s full, Columbia’s existing ASR well holds 31 million gallons of water and looks like an underground flask capped by a pumping station. The city stashes extra water in the well during winter nights, when water use is low.

When the city wants it back, usually during peak days in July and August, they pump it out at a rate of 2 million gallons a day. It’s a slow process, akin to sucking a milkshake through a straw.

ASR-stored water is treated, so it doesn’t taste, look or smell any different than tap water, Vandike said. The city tests for pathogens each week, just in case, but the freshly treated water fights off most bacteria and mineral hardness, he said.

Although it is new to the Midwest, ASR technology has been controversial in Florida, where communities have used it to displace poor, salty groundwater. Opponents there have argued injections into Florida’s fast-moving groundwater system rough up wetlands via cracks and fissures in aquifers.

Not so with mid-Missouri’s geology, Vandike said. In Florida, water rushes through an aquifer. In Missouri, by comparison, it slowly creeps. Also, the dolomite and sandstone composing the aquifer beneath Columbia are sturdier than Florida’s brittle karst systems.

“If it’s a success, great,” said Bill Scheperle, an environmental engineer with Missouri’s Public Drinking Water Program. “If it’s not, it’s not like we’re looking at a major pollution problem.”

Vandike said, ASR is catching on especially in the Midwest as an uncontroversial, cheap, non-problematic method of storing an emergency water supply without building expensive equipment. The technique has also been used in Iowa and Wisconsin.

“It’s not like you have to build a 10,000-gallon storage tank,” he said. “You just put the water in the ground.”

Columbia eventually will outfit up to three wells with ASR systems, said Turner. The technology will not replace water towers, he said, but it will help quench the city during water emergencies without tapping into expensive neighboring water lines.


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