DEQ authorizes Molalla to discharge fully treated effluent during low river flows
Oregon's Department of Environmental Quality has approved a request by the city of Molalla to discharge fully treated effluent to the Molalla River from the Molalla wastewater treatment plant while the river flow is less than 350 cubic feet per second. That's because the weather hasn't provided enough rain.
"DEQ made a determination that we've done everything we were supposed to do, but the weather is not cooperating for us to discharge," said Gerald Fisher, Public Works director.
Normally, the city can discharge treated effluent to the Molalla River from Nov. 1 through April 30, as long as the seven-day flow average of the river is at least 350 cubic feet per second. But since the recent lack of rain in October and early November, water levels dropped below 350 CFS before Nov. 1, according to the state agency.
DEQ understood the problem noting the plant lagoons were nearly full. In a letter to Fisher, they said the lagoons were at 11.4 and 11.6 feet in depth on Nov. 1. "Maximum allowable depth is 12 feet and no appreciable rain was forecast within the seven-day forecast," according to the letter.
The letter also mentioned that emergency disposal of effluent to Bear Creek is not an option except in the most-dire circumstances, which are too much rain and influent flow where either the effluent pumps can't handle the discharge or have totally failed. That option isn't permitted during current conditions.
"We couldn't hold any more water at the plant, so we requested the DEQ allow us to discharge and they granted it," said Fisher. He noted that the discharge allowed the water in the lagoons to drop to 10 feet and the city discontinued the discharge. "That should buy us some time for the rain to come back and bring the river levels back up to 350 CFS or higher."
"DEQ determined the city plant and its operation are not at fault. All steps have been taken by city staff to prevent early discharge in October and reached plant limitations in November for water storage in its lagoons," Fisher explained on the Molalla website. He praised the staff for working to protect the Molalla River and do everything necessary to remain in compliance with the permit and the Mutual Agreement Order with DEQ.
"Molalla Public Works staff has worked tirelessly to improve the operation of the wastewater treatment plant, manage biosolids removal, treat effluent and make needed repairs to the collection system, all while complying with the NPDES permit and MAO between the city and DEQ," Fisher said on the website.
Fisher noted this has nothing to do with the new permit. "There won't be a new permit until we are closer to finishing the design of the new plant. We are just starting the preliminary engineering phase of the plant and should be starting design by the end of spring 2020."
As to the next quarterly report, which should be posted the week of Nov. 18, once Consultant Holly DeRamus finishes it, there were no violations in August, September of October, Fisher pointed out.
You count on us to stay informed and we depend on you to fund our efforts. Quality local journalism takes time and money. Please support us to protect the future of community journalism.