ITB-3812 - Water Treatment Chemical-Granular Activated Carbon (GAC)

Summary of Specifications:
The City of Ann Arbor Purchasing Division is soliciting bids for virgin, bituminous-based Granular Activated Carbon (GAC) for use in the Water Treatment Plant rapid sand filters. The GAC is to perform the dual function of adsorption of taste and odor-causing organics, and as a filtration medium for effective turbidity removal in the processing of water for potable use. 

The Water Treatment Plant has 26 GAC and sand filters, 10 of which contain 22 inches of GAC and 16 of which contain 18 inches of GAC, over a 6 inch thick layer of sand. Below the sand, on 16 filters, are various layers of gravel. The gravel and sand are separated by a stainless steel screen which prevents the gravel from mixing with the sand during the backwash operation. There is no gravel in 10 filters.