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TO: Mayor Thomas J. Weisner
FROM: David E. Schumacher, P.E.; Superintendent of Water Production
DATE: July 29, 2014
SUBJECT:
A Resolution Authorizing an Addendum to the Amended and Restated Potable Water Service Agreement with Calgon Carbon Corporation (Calgon) for the lease of Granular Activated Carbon (GAC) in filters 5 - 8 for the Water Production Division (WPD).
PURPOSE:
To obtain City Council approval for an addendum to the subject agreement for pricing and installation of GAC for filters 5 - 8 in 2014 at the City of Aurora Water Treatment Plant (WTP).
BACKGROUND:
The WTP has 12 dual-media filters which contain sand and GAC which are used to remove solids prior to disinfection of the water. In addition, the GAC media serves to remove taste and odor compounds which are adsorbed onto the GAC which remains in the filter. Over time the GAC is expended (spent) and needs to be replaced/refreshed, typically between 36 and 42 months. This is done on a staggered schedule in three groups of filters, filters 1 - 4, 5 - 8, and 9 - 12.
The WPD currently leases GAC under an existing agreement with Calgon. Historically, the WPD has always utilized brand new GAC, otherwise known as "virgin" GAC. Due to escalating costs of virgin GAC, Calgon has provided an option to utilize "reactivated" GAC under their Custom Municipal Reactivation (CMR) program. Reactivation, in simple terms, is the high temperature heating of the spent GAC which volatilizes the adsorbed compounds thus returning the GAC to additional productive service. The opportunity for cost savings from utilization of reactivated GAC is significant without sacrificing substantial performance when compared to virgin GAC.
Earlier this year the WPD began a trial to compare the performance of reactivated GAC versus virgin GAC in filters 1 - 4. As the trial is in the very early stages, performance and longevity data is not yet available for the reactivated material. Based on the avail...
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