TO: Mayor Thomas J. Weisner
FROM: David E. Schumacher, P.E.; Superintendent of Water Production
DATE: November 5, 2013
SUBJECT: title
Resolution Authorizing the Execution of an Amended and Restated Potable Water Service Agreement with Calgon Carbon Corporation for the Continued Lease of Granular Activated Carbon for the Water Production Division.
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PURPOSE:
To obtain City Council approval for the execution of an Amended and Restated Potable Water Service Agreement with Calgon Carbon Corporation (Calgon), Pittsburgh, PA, for the Continued Lease of Granular Activated Carbon (GAC) at the City of Aurora Water Treatment Plant (WTP) to include pricing options for the use of both virgin and reactivated GAC.
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 Water Production Division (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. Reactivated carbon has been utilized in the potable water treatment industry for many years and is widely accepted for use in different treatment applications. The opportunity for cost savings from utilization of reactivated GAC is significant without sacrificing substantial performance when compared to virgin GAC.
DISCUSSION:
As the GAC in filters 1 - 4 is needing replacement, the WPD solicited and received cost options from the two major and reputable suppliers, Calgon and Cabot Norit Americas Inc. A third supplier was considered, but their raw material is from foreign sources and is undesirable in comparison to domestically sourced and prepared GAC. The replacement unit cost of virgin GAC ranged from $45.06 to $49.40/cubic foot and reactivated GAC from Calgon is $29.70/cubic foot. Thus, the reactivated GAC unit cost is approximately 60% of the virgin cost and should be considered for use due to the potential for significant monetary savings. The options provided by the suppliers are listed below.
Supplier Option Total Cost (for 36 month period)
Calgon Reactivated GAC Trial Option (as described below) $382,844.00
Cabot Purchase Virgin GAC & Lease Exit Costs $436,164.80
Calgon All Virgin GAC $478,192.00
The WPD has considered and investigated several options regarding the use of virgin versus reactivated GAC. The WPD's recommendation is for two filters from this group (filters 1-4) to receive virgin GAC and the other two filters to receive reactivated GAC. Thus, a side-by-side evaluation (trial) of actual performance can be achieved. As reactivated GAC has never been used before at the Aurora WTP, conducting a side by side trial allows staff to confirm the adsorptive and physical filtering performance of the reactivated GAC compared to virgin GAC. It is important to note that the reactivated GAC is the same media that is removed from these filters, returned to Calgon for reactivation, and subsequently reinstalled at the WTP.
Funding for leasing of GAC is provided annually in the WPD budget Account No. 510-1851-511-38-28.
IMPACT STATEMENT:
None.
RECOMMENDATIONS:
That the City Council authorizes the execution of the Amended and Restated Potable Water Service Agreement with Calgon for the continued lease of GAC at the WTP to include pricing options for the use of both virgin and reactivated GAC. It is further recommended that this matter be forwarded to the Buildings, Grounds, and Infrastructure Committee for their review and approval.
cc: Alderman Peters, Chairman
Alderman Garza
Alderman Bugg