The Mount Prospect village board has approved repairs to the lining of one of the deep wells that provides a backup for the village's Lake Michigan water system.
At a cost of $276,000, not including a $25,000 contingency, a narrow liner will be installed.
At one time, Public Works Director Sean Dorsey told the board Tuesday, the village once had as many as 15 deep wells, which were the sole source of water for the village.
Today, the village retains five deep wells as an alternate water source in the event that there might be a problem getting water from Chicago or there is a problem with the Joint Action Water Agency pipeline that supplies the village with Lake Michigan water.
"We have maintained these wells pretty vigorously over the years," he said.
It was during the maintenance of Well No. 5 on Highland Avenue that the problem with the liner was discovered. In July 2012, at a cost of $163,000, a 500-horsepower electric motor was removed and the piping was pulled from a depth of greater than 1,000 feet. The village spent $40,000 repairing the corroded pump and brush cleaning the well borehole.
A camera was also used to determine if there were any defects in the well, which uncovered numerous holes in the well liner caused by corrosion. They ranged from 1 inch to several inches in diameter.
Several options were considered, including abandoning the well at a cost of $165,000, or drilling a new hole at an expense of more than $1 million.
Dorsey said the village consulted Baxter & Woodman, which advised against abandoning the well, noting that the capacity from the well would be necessary to satisfy the Illinois Environmental Protection Agency's maximum daily demand requirements. In addition, the well has an emergency standby generator capable of running the well for extended periods of time.
"I think there is some cost to maintaining it," Trustee Steven Polit said in voting to spend the money, "but I think the cost of not maintaining it, and not having that opportunity for that second wave to generate water for our residents, would be much more costly."