Wastewater project: Phase one complete
Sixteen months after construction began on the $20 million-plus upgrade of Marietta’s wastewater treatment plant, the first phase of the project is winding down and initial work on the second phase is underway.
“Phase 2 has just started, and we’re projecting it to be completed by August 2014,” said Steve Elliott, wastewater superintendent.
He said the project’s initial phase has had no major setbacks and is currently right on schedule, thanks largely to a value engineering process used during design of the first phase.
“And a lot of what we’re doing in the second phase has resulted from the value engineering study, too,” Elliott said. “This was not a useless study-it’s helped us very much, and was worth every dollar the city paid for it.”
He noted the city has realized some major savings on the project due to the value engineering study, including about $3 million on replacement of two anaerobic digester tanks at the facility that were part of a major equipment failure at the plant in January 2010.
“Those tanks will be changed to aerobic digestion, which is a huge savings over replacing them with another anaerobic system,” Elliott said, adding that the aerobic waste digestion process does not create the methane gas that blew the lid off of one of the anaerobic tanks during the 2010 equipment failure.
Aerobic digestion of waste makes use of oxygen in the process while anaerobic digestion does not include oxygen but gives off methane.
A major part of the project’s $4.4 million first phase was an upgrade of electrical power needed to operate the wastewater plant. A new electrical building has been constructed at the western end of the treatment plant property which is located along East Eighth Street.
“The electrical upgrade includes a new backup power generator,” Elliott said. “But we’re also keeping our old unit which is still in good condition, and there will be a third generator installed as part of the third phase of this project.”
He said a large canopy erected at the front of the electrical building and generator will house a new ultraviolet light system to disinfect treated water before it is discharged into the Ohio River.
Clarifier tank pumps, as well as pumps designed to prevent river water from entering the wastewater treatment system during periods of high water have also been installed during the first phase.
“We’ve added extra space for equipment we know will be needed in the future to remove phosphorus from the water before it goes back into the river, too” Elliott said, noting the U.S. Environmental Protection Agency is expected to eventually mandate phosphorus removal at all wastewater plants that discharge into river systems.
In addition he said plans for the project have focused on attempting to keep all of the new facilities out of the 100-year flood plain.
“I think it’s all proceeded very smoothly so far,” Elliott said of the first phase.
The $5.88 million second phase construction is being done by PAE Associates of Brookville.
Tht second phase will address all of the plant’s solids handling systems, including improvements to the sludge dewatering process, which should greatly reduce offensive odors that plagued the neighborhood around the wastewater facility following the January 2010 plant failure.
Responding to complaints from businesses, including restaurants and motels in the area, Marietta City Council approved the temporary use of an odor-reducing chemical that’s injected during the sludge dewatering process.
Elliott said the chemical injection has worked quite well, and there have been few complaints about the odor since that process began in mid-2012.
“But during the last week or so we did have a problem when the company we contract with to haul away the sludge had to have their truck repaired,” he said. “That delayed getting rid of the sludge for a week. We continued injecting the odor-control chemical during the sludge processing, but the chemical only lasts up to 72 hours, so there was some noticeable odor during that time.”
Elliott said the sludge hauler’s vehicle has been repaired and the material is being removed from the site again.
He said the chemical odor-reduction process is continuing, although some adjustment of the amount of product injected will be required as spring and summer return.
“With the onset of warmer weather we’ll have to increase the feed rates for the chemical, which may take a little time to make that adjustment,” Elliott said.
Once the entire project is completed the new plant upgrades are designed to last another 20 years.
Marietta Councilman Mike McCauley, D-2nd Ward, said the city council has budgeted $11 million this year and another $11 million for 2014 toward the wastewater treatment plant project.
As the $20 million project moves into its second phase, city engineer Joe Tucker is headed to San Diego, Calif., to give a special presentation related to the project during the American Public Works Association Conference on Sustainability May 15.
“We’ve titled the presentation ‘Making Financial and Environmental Sustainability the Focus for Wastewater Treatment Plant Improvements,'” Tucker said.
He hopes the presentation will be of some help to other city engineers who may be planning the renovation of their own wastewater plants.
“The upgrades we’re making on our plant will represent the largest capital improvement this city has made in the last 25 to 30 years, and it’s a complicated effort,” Tucker said. “So it took quite a bit of work to put this presentation together, but hopefully it will help other engineers from smaller cities who are faced with a similar situation.”
He worked on the presentation with Dale Kocarek, engineer with Stantec Consulting Service, Inc. of Columbus, which is providing design and engineering services for the wastewater project.
“We’ll talk about the intergovernmental agreement between the city and county which saved Washington County more than $3 million over having to build a new wastewater treatment facility in Devola,” Tucker said.
“By 2017 we’re estimating the Marietta plant’s flows will increase by 11.7 percent, which will also provide additional revenue to help pay off the 20-year loan for the facility improvements,” he said.
For the first two phases of the plant upgrade project the city will also save on loan interest, thanks to two wetlands projects the city council has agreed to help sponsor through the Coastal Wetlands Planning Protection and Restoration Act.
Tucker said the reduction in interest represents a total savings of nearly $120,000 over the 20-year term of the city’s loan to cover the wastewater plant project.
“These savings may seem small when compared to the overall cost of the project, but when taken altogether, they can represent a significant reduction in cost,” he said.
Tucker said he also met with many engineers from other communities that have upgraded their wastewater systems to learn what has or has not worked for their facilities, then applied that information to the design for the Marietta project.
He said his message to fellow engineers during the American Public Works session in San Diego will be that such savings opportunities don’t just materialize.
“You have to actively look for those opportunities and become aware of them,” Tucker said. “Thomas Edison said ‘Opportunity is missed by most people because it’s dressed in overalls and looks like work.”
He emphasized his expenses for the San Diego trip are being covered by the state board of the American Public Works Association of which he is a member-and not by the city of Marietta.