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TO: Mayor Thomas J. Weisner
FROM: David E. Schumacher, P.E.; Superintendent of Water Production
DATE: February 16, 2016
SUBJECT:
Resolution to authorize a Professional Services Agreement for mine repurposing consulting services for the Lime Residual Underground Injection Control project for the Water Production Division.
PURPOSE:
To obtain City Council approval to attain a professional engineering services agreement with CNA Consulting Engineers, Minneapolis, MN (CNA) for mine repurposing consulting services for the Lime Residual Underground Injection Control project for the Water Production Division.
BACKGROUND:
All residents of the City of Aurora are provided with potable water from the city owned and operated Water Treatment Plant (WTP). The main treatment process utilized at the WTP is the lime-softening process. This process not only removes and collects the solid particles that are present in the raw water sources (Fox River, shallow well, and deep well water), but also softens the water to provide customers with more aesthetically pleasing drinking water. As the solid particles are removed by the treatment process, they are concentrated and collected and this by-product must be ultimately disposed.
Since the WTP's construction in 1992, the lime residual has been disposed by landfilling at great annual expense to the city. In 2012, through an IEPA permit, the WPD began a program to dispose of the lime residual via land application on agricultural fields. Land application allows a beneficial reuse of the waste product and reduces the cost of ultimate disposal by approximately 25%. As this process is still expensive, starting in 2006, a more efficient method of ultimate disposal was investigated regarding placing the lime residual in repurposed portions of a limestone mine.
DISCUSSION:
The LaFarge-Conco Limestone Mine (LC-Mine) is located at the intersection of Interstate 88 and IL Highway 25. The mine is approximately...
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