Hoffman Contractors wins $8.5 million Cheney project

The city of Cheney has awarded an $8.5 million contract to Hoffman Contractors Inc:, of Spokane, to expand its wastewater-treatment plant, essentially doubling the facility's capacity. The contract amount represents about a $2 million savings for the city, which originally estimated the project would cost $10.4 million, says Don MacDonald, Cheney's public works director.

MacDonald says the expansion of the plant is needed because during high-flow periods the plant has reached 85 percent of the maximum amount of pollutants it can treat, as defined by the Washington state Department of Ecology. After its capacity is increased, it can treat wastewater longer during high flows, thus avoiding reaching the maximum limits on those pollutant measures. MacDonald says the work is being paid for with a zero-interest loan from Ecology.

The project is being designed by Esvelt Environmental Engineering LLC, of Spokane, and includes expansion of the plant's biological treatment facilities and its solid waste composting facility, both of which are located at 119 Anderson Road, east of the Cheney city center, MacDonald says. Hoffman will begin work on the project in mid- to late-July and will complete it in one year, MacDonald says.

In the expansion, additional facilities and equipment will be added to the plant, including additional conditioning tanks, which are used to remove phosphorous from the wastewater; an additional aerator in each of the facility's two aeration basins; an additional solids holding tank; and a second solid waste press, which is used to extract moisture to prepare sludge for composting.

Also, the facility's chlorine gas disinfectant system will be converted to a liquid chlorine system, which MacDonald says will be much safer for plant operators and the public. The electrical wiring and controls at the plant also will be expanded to accommodate the additional equipment, he says.

The plant's compost building will be doubled in size to handle 16 rows of compost, up from the eight rows it now has, MacDonald says. Each row holds up to 420 cubic yards of solid waste that has been separated from the wastewater in the treatment process. Wood chips and yard waste are added to the compost mix, which is cured for eight weeks, then sold to landscaping companies.

MacDonald says that later the city plans to convert the facility to a water reclamation facility, which would mean its treated wastewater could be used for irrigation.

To do that, the facility would have to convert its chlorine disinfectant system to one that uses ultraviolet light to disinfect, but the city has postponed that step because of the high cost of such a conversion, MacDonald says.

Copyright Northwest Business Press Inc. Jun 26, 2008
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