Sewer plant odors may abate in December

Odors at the town sewage plant could subside somewhat in early December, when the operation of a temporary plant expansion would mean the town starts exporting sludge to a county sewage plant on Ina Road, town officials said.

The Town Council at its Nov. 13 meeting approved the exporting of sludge to the Ina Road plant and also approved a 74 percent increase in monthly sewer fees, among other actions.

Sludge will be exported, council members were told, because town staff decided months ago not to process on site the sludge that will be produced by the four temporary package plants.

Instead, sludge will be hauled every two or three days to the Pima County wastewater plant on Ina Road, where it will ultimately be dumped in a county landfill.

Town Manager Jim Stahle told the council, “We intend to run the package plants at maximum capacity, which will mean less sludge in the drying beds. This will help odor problems because there won’t be the same quantity (of sludge).”

Assistant Town Manager Larry Dobrosky later said that operating the package plants at full capacity is the most efficient way to operate them.

Adding capacity

The permanent plant now has a permitted capacity of 490,000 gallons per day, and the four package plants will add another 200,000 gpd.

The permanent plant produces sludge that is processed in odor-causing drying beds. The amount of sludge to be processed locally will be reduced by about 40 percent at first because the package plant will run at full capacity, Dobrosky said, but the amount will climb as new homes are connected to the plant.

The assistant manager said there is no way to know how much the odors would be reduced.

The town began testing the expansion last week with clear water.

“There was some leakage, a normal thing. That’s why we start with clear water. Everything is coming along perfectly” for approval and operation starting in the first two weeks of December, Dobrosky said.

The town planned to resume testing last Monday, Nov. 27. After testing is completed, current staff will need training and permits must be issued by the state Department of Environmental Quality, the assistant manager said.

Cost questioned

Regarding the decision to process the additional sludge off-site, council member Scott Downs said, “This should have been brought up when we approved the package plant. We got bit on the right and now we got bit on left. Do we have a cost on this?”

Stahle said, “I’m sorry that the council was surprised by this cost. It was our fault. Maybe we didn’t explain this effectively months ago.”

Dobrosky told the council the sludge-exporting process will cost the town an estimated $15,000 a month overall, and he later noted that the net cost would be less because the town would have to pay for shipping and landfill fees even if it did processing on-site.

The decision was made because local sludge-processing would cost more in the construction of permanent drying beds, would cause greater odor problems and would delay the start-up of the permanent expansion, the assistant manager said.

The town originally planned to connect the four package plants one at a time but discovered during the construction process that it was more efficient to connect them all at once, the assistant manager said.

The overall cost of the package plants is $3.3 million. It is a capital expense and is being financed as part of a loan of up to $20 million from the state Water Infrastructure Finance Authority, which is paying for the permanent plant expansion.

The town so far has not used monthly fees, which are intended for operational costs, for plant expansion.

It plans to repay the WIFA loan from connection fees from new customers, Dobrosky said.

The permanent expansion has been approved to a 1.5 million gpd capacity and is expected to open in the summer of 2009.

In that phase, the town is considering a technology that would replace the outdoor drying beds with a process for drying sludge indoors and scrubbing the fumes, “so the air going out would be clean air,” Dobrosky said.

Stahle said the current operation, using drying beds, was the cheapest approach, but every time it is disturbed, for example when sludge is hauled away from a bed, “it creates an odor, which is a major problem ... though it (an indoor system) is more expensive, considering the proximity of homes to the facility, this is a must to get this problem solved.”

pfranchine@sahuaritasun.com | 547-9738

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