Upgrade to Marietta treatment plant almost complete
Trending
As concrete leaves lowered into place Tuesday at the wastewater treatment plant in Marietta, an engineering marvel 10 years in the making took shape.
"This project has spanned nearly a decade and to be financially in good health and still on track with your goal is huge," said Ryan Taylor, president and CEO of Pickering & Associates, to those gathered to watch the installation of the new clarifiers at the plant.
These final clarifiers mark the last large construction feat of a multi-phased, many-scoped project that has been planned for more than three decades, as the refuse passing through the treatment plant not only increased in volume, but had more regulations on how it was treated and released.
The original plant was built in the mid-1950s and the last major renovations took place in the late 1980s. But that upgrade completed in 1987 is now more than 30 years old --11 years past the average lifespan of a wastewater plant operating at capacity.
"And now we're taking in and cleaning out much more than we were back then," explained Adam McKenzie, electrical maintenance supervisor, as he showed where the current clarifiers, which are 50 years old, separate liquid from solids before sending the liquid to be disinfected and discharged.
The new clarifiers are the bulk of Phase III Scope 4 of this most recent renovation to the plant, which began in 2011 after six years of facilities planning, studies and determinations of design criteria for the upgraded plant.
"I don't think you're ever done because the regulations are always changing and tightening," said Steve Elliot, wastewater superintendent. "We're looking on the horizon at possible regulation coming on nutrients, but this completes that last long vision plan."
Clarifiers, in laymen's terms, are the final separators of solids and liquid before the liquid is filtered and pours into the Ohio River as clear and clean water.
"The sludge then gets pumped back into the process, and some of it is waste hauled off site," explained McKenzie.
On Tuesday the contractor installing the new clarifier, Dutchland, had representatives on-site to explain how the new clarifiers will meet the higher capacity need of the city, and once complete be practically hidden from site of passersby.
Dutchland came on to the project in 2013.
"We precast in our shop (in eastern Pennsylvania) and then pour the bases on site," explained Mike Schmidt, of Dutchland. "Then we thread post-tension cables through the buttress."
Each panel in the walls surrounding both circular clarifiers is made of preshrunk concrete, Schmidt explained, that will then be synched and caulked to be completely watertight, then once complete each tank will hold 660,000 gallons of wastewater.
"These panels will sit one foot above the 100-year floodplain," City Engineer Joe Tucker explained, pointing out that valves beneath the base of each clarifier will also serve as a prevention of flooding.
Scope 4:
¯ The last large scope of work under the renovation of the city wastewater treatment plant includes installation of new final clarifiers, ultraviolet disinfection, a high river pump station and associated landscaping and backfilling to allow for easy maintenance.
¯ The project has been under construction since Dec. 26, 2017 and is projected to reach substantial completion by the close of summer 2019.
By the numbers:
Phase III, Scope 4 costs:
¯ Engineering: $391,777.73.
¯ Construction: $8,441,100.
¯ Construction administration: $554,585.
¯ Contingency: $444,970.
Total: $9,832,432.73.
Funding Summary:
¯ Appalachian Regional Commission Grant: $250,000.
¯ Ohio Public Works Loan Assistance: $135,553 (grant which pays for the capital interest on the loan during construction).
¯ Water Pollution Control Loan Fund through the Ohio Environmental Protection Agency: $9,446,879.73
Source: Marietta City Engineering.