Aurora mine to store water treatment byproduct

The city of Aurora has found a new home for one of the byproducts created by the city's water production plant. It's just down the road — and under the ground.

Lime sludge generated from turning Fox River water into drinking water will be stored in empty underground spaces created by a company that mines limestone from a city of Aurora property, under a lease the city council approved Tuesday night.

The lease requires LaFarge Aggregates Illinois to pay the city royalties on mining operations and to construct some parts of the infrastructure that will allow the city to store lime sludge in the empty portions of the mine, located at Route 25 and Mettel Road.

The city council approved the lease unanimously, with some saying it provides a cost-effective solution to the ongoing problem of lime sludge storage. The sludge currently is taken to landfills at a cost of about $1.2 million a year.

“It's a solid way to dispose of a concern we've had for a long time and good results in the long run,” Alderman-at-Large Bob O'Connor said about the lease.

Aurora expects significant savings on the cost of storing lime sludge throughout the lease's term, said Alex Alexandrou, Aurora's chief administrative services officer.

“We're looking at saving over the 30-year period about $45 million,” he said.

Savings won't be seen until six years into the contract because it will cost the city $6.5 million to build the underground lime sludge storage system. But once the system is built, costs decrease to about $200,000 a year.

Royalties from LaFarge expected to total $3.5 million over 30 years will add to the city's savings total, bringing it to a projected $48.5 million.

LaFarge will assist with some aspects of turning the empty sections of its mine into storage. The company will build bulkheads to seal off the large space into smaller rooms and berms to create basins to hold the sludge, Alexandrou said.

With the contract approved, the city now can seek permits for underground work with the goal of having the new lime sludge storage system operational by April, 2015.