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Bid Date/Time: Jan. 29, 2 p.m.

In 2007, the city found evidence of midge fly infestation in the water system. The city identified and repaired potential entry points, and also conducted extensive flushing to mitigate the infestation.

In 2009, a new infestation occurred, and larvae were found throughout the distribution system. Midge fly larvae are resistant to free chlorine, but are susceptible to inactivation by relatively low levels of chloramines. The city’s water has some naturally occurring ammonia in each of its groundwater sources, and the plan is to select and install on-site sodium hypochlorite facilities at each plant to create a chloramine residual for treatment of its distribution system.

The city of Woodburn is seeking proposals for the analysis, planning, design and implementation of disinfection for its drinking water system. Preliminary assessment of alternatives indicates that the chloramination disinfection process appeals to the city. Proposals submitted that identify alternatives to chloramination will be evaluated based upon technical merit. The proposed scope of work consists of chlorine chemistry evaluation, equipment selection, design, and start-up and implementation.

The review process will include technical and cost proposal rankings. Selection of a firm is scheduled for Feb. 12.

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