City exploring aquifer well option to add water capacity [Herald & Review, Decatur, Ill.]

Nov. 28--DECATUR -- Decatur City Council members could approve a plan soon that may net the city a significant increase in water capacity if a local aquifer can yield enough, said Keith Alexander, water management director.

"It's not only insurance, but it would give all of our customers -- residential, commercial and industrial -- the assurance that we have plenty of water for their needs," Alexander said.

Alexander and members of engineering firm Black & Veatch presented the possibility of one or two collector wells to the council last week, which they said could be a big step toward the 10,000 acre-feet of extra water the city officials have been seeking.

"The preliminary estimate is that two collector wells could provide 4,700 acre-feet to 8,060 acre-feet," Alexander said. "That's if this new study indicates we could support two well systems near the South Water Treatment Plant."

Collector wells are cylindrical, concrete constructs submerged in the earth to draw in water through filtering screens that trap sediment and allow water to flow through. Alexander said pumps would then convey the reclaimed groundwater to the South Water Treatment Plant for processing.

Alexander said staff members estimate a two- to three-year project at a cost of about $5 million, assuming two collector wells are built. Some of that money might come from past bonds, he said.

Alexander said city staff should have a proposal authorizing an engineering study ready for the council's vote at its Nov. 21 meeting. That first phase, at a cost of $70,050, would bore into the ground at six to eight points to create observation wells, allowing engineers to determine the thickness of the sand and gravel aquifer and how much water it is likely to yield.

Alexander said previous test borings have led engineers to believe there's water to be had.

"Black & Veatch is fairly certain the sand and gravel aquifer is present in a large quantity and appears to be continuous along most of that stretch," Alexander said. "The only way to know for sure is to literally bore more test borings and test those readings as well."

The first phase would likely be complete by spring of next year, he said.

If successful, the project could mean a major step toward easing water concerns during dry summers such as the one Decatur just weathered, Alexander said.

"The bottom line is that the collector well option can potentially provide half of the water that our community needs to get through a severe drought lasting approximately eight months, and that's as long as the worst droughts of the last 102 years in this part of the state," he said.

[email protected] 421-7985

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