cover
TO: Mayor John Laesch
FROM: Jason Bauer, Director of Public Works/City Engineer
Robert Leible, Superintendent of Water Production
DATE: November 13, 2025
SUBJECT:
Fourth Amendment of the City's existing lease agreement with Amrize Mid-America, Inc., (Amrize) formerly known as Holcim-MAMR, Inc.
PURPOSE:
To update and clarify specific language in the existing lease agreement as the Fourth Amendment to the Second Amended and Restated Lease between Amrize and the City of Aurora without needing to renegotiate any terms.
BACKGROUND:
The Amrize limestone mine is located at the intersection of Interstate 88 and IL Highway 25. The mine is approximately 200 to 400 feet below grade, is located in both Aurora and North Aurora, and is mainly used to produce limestone and dolomite aggregates for construction uses. The portion of the mine located in Aurora is typically referred to as the south mine and currently has two distinct levels with a third level to be constructed in the future. The first two levels of the mine are basically completely excavated and thus are no longer useful for material production. Mining activities have transitioned to level 3 and are estimated to continue for a decade.
Lengthy discussions between Amrize and the City have produced two options for disposal of lime residual material produced by the City's water treatment process. Initially the Illinois EPA (IEPA) issued an Underground Injection Control permit in 2015 to pump lime slurry to excavated areas of the south mine. This method was not implemented. Subsequently in 2016, an alternate transfer method to place dried lime residual material into the Amrize mine was conceived. Additional regulatory approvals were needed for the alternate transfer method. In 2023 legislative approval was received via House Bill 3095 and signed by the governor in July 2023, with an effective date of January 1, 2024. This approval requires the Illinois Pollution Control Board (IPCB) to adopt the rul...
Click here for full text