First repairs in renovation of wastewater plant to begin in May

The city of Marietta's aging wastewater treatment plant is slated to receive a multi-year, multi-million dollar renovation and the components prioritized for renovation in 2009 are three primary sedimentation basins where solids settle from the wastewater.

The basins are fundamental and have been part of the plant since it went online in the mid-1950s.

The last renovation of Marietta's wastewater treatment plant took place in 1987.

Marietta Wastewater Superintendent Steve Elliot said the machinery of the primary sedimentation basins is designed to last about 20 years. Though the machinery has been maintained, it is in need of repair and no longer meets EPA requirements and standards.

It's like any other mechanical device; after years of running 24 hour a day the process “gets sloppy,” Elliot said.

Marietta's wastewater treatment plant has three primary sedimentation basins but is currently running on only two, Elliott said.

The renovation of these sedimentation basins is only the first step in updating the wastewater treatment plant and its processes. Many of its other components are in need of repair as well, including pumps, sludge-thickening equipment, and final clarifiers.

In an effort to save money, the three sedimentation basins are going to be renovated up to current EPA standards. There is no standard size for all the parts needed to rebuild the three basins and every chain, motor, sprocket, and gear is made to order, Elliot said.

"In 2008 we operated at 95% of design flow, and 96 days we were above design flow, so on an average day we’re just under capacity. It varies with precipitation and river levels. In 2007 we operated at 108% and in 2006 we operated at 102%," Elliot said.

That means the plant at times is operating beyond the capacity it was designed to handle.

Elliot said Marietta's wastewater treatment plant is capable of treating 3.34 million gallons a day while meeting its EPA permit requirements.

In wet-weather conditions the plant can utilize a hydraulic system to move 2.6 million gallons to an equalization basin for storage and treat up to the maximum hydraulic design of 8.25 million gallons, but that level of operation cannot be sustained for long periods of time without violating EPA requirements.

Elliot said there were 33 in 2008 when the plant operated above the maximum hydraulic design.

Marietta's wastewater treatment plant received three minor violations in 2008, Elliott said, and if “we lose a major process, we’re in danger of losing our permit," he said of the EPA National Pollutant Discharge Elimination System permit needed to discharge treated wastewater into the Ohio River.

So far about 30% of the final designs have been completed for the wastewater treatment plant's renovation. Elliot said the renovation process cannot go much further until negotiations are concluded between the city of Marietta and Washington County.

City and county officials are working on a plan to extend the service area of Marietta's wastewater treatment plant to parts of Washington County within reasonable distance. Areas under consideration include Oak Grove, Devola, areas of Ohio State Route 7 North around Reno and areas of Ohio State Route 7 South, Elliot said.

If such areas are included, the wastewater treatment plant will need to be renovated to handle a higher capacity.

Once the final design is finished the plan will go to the city engineer for a project cost estimate.

Elliot figures that amount will be somewhere between $12 and $15 million, but said it is hard to estimate at this time because the project's scope depends on what city and county officials decide to do.

Over $1 million in funding for the project's design was secured through low interest loans from the Ohio EPA, Department of Environmental Financial Assistance. These might be rolled over into construction loans.

Other possible sources of funding are State and Tribal Assistance Grants from EPA and the federal stimulus package in development, Elliot said.

The first stage of the update to the three primary sedimentation basins is set to begin in May.

A contract has been awarded to Downing Construction of Baltimore, Ohio. Downing was the low bidder and won the job at the price of $343,370, Elliot said.