Sutton said Mack has been a customer since the plant opened, and represents by volume about 10 percent of the wastewater that comes into it.
The proposal to improve the plant came from the county Water and Sewer Department in its proposed five-year Capital Improvements Project budget.
If approved, the work would be done over the next two fiscal years.
The pretreatment plant was built to handle leachates, which come from water runoff at landfills, and the kinds of wastes produced by dairy operations or plants involved in such things as food production, Rohrer said.
Manufacturing plants such as Mack that are involved in metal finishing typically generate oily waste when they cool their machine tools, Sutton said.
"The plant was never designed to handle oily waste, and it's not properly equipped to do so," said Rohrer.
He said the plant was not violating any environmental regulations.
The plant is operating at an average of 80 percent of capacity, Sutton said.
Because of the problems caused by its waste, Mack's waste-handling fees were raised on Feb. 1 from $65.99 per 1,000 gallons to $130 per 1,000 gallons, a county finance official said.
The Water and Sewer Department's capital improvements requests also include:
- $100,000 for better removal of grits and solids from the waste stream.
- $165,000 to design and install a system for treating Fuji photo finishing's wastewater.
- $110,000 to buy and install a forced air and water system to clean out plant holding tanks and lines where residue is building up. Sutton said the plant was built without such a system.
When the capital improvement requests were presented to the Washington County Commissioners two weeks ago, Commissioner James Wade questioned the need for improvements.
"If we're not making money on it now, is it a smart move to put $1.7 million in improvements to the plant now?" he said. "And the biggest fix is for a customer who only represents between 5 and 10 percent of the flow coming in."
Commissioner R. Lee Downey said that before making a decision, he'd like to see the results of a planned county study on how the pretreatment plant can be better marketed.
Commissioners Ron Bowers and John Shank could not be reached.
Snook said the commissioners will decide in 30 to 45 days whether to fund the improvements. He said money to pay for the work likely would come out of the county's general bond issue.