MONROE - The city will stave off a half million dollar bill for a new digester cover by opting to repair the old cover for less than $50,000.
The Monroe Board of Public Works voted unanimously Monday, Dec. 16, to follow the recommendation of AECOM, hired by the city to oversee the wastewater treatment plant upgrades which began in April.
Digester Cover No. 2 was installed about 1972 and has been in service for about 40 years. It was sandblasted and recoated in 1989, according to AECOM.
Construction contractors for the current facility upgrade recently removed the cover and discovered it had significant corrosion on the underside. After the steel skirt and underside of the cover had been prepped and new coating applied, Dixon Engineering Inc. did a formal assessment and identified areas of corrosion on the skirt.
The deepest pits in the skirt were measured to be 3/16-inch deep, leaving 1/16 inch of steel, about one quarter of its original thickness. Metal on the top of the cover is in good condition with no metal loss.
By repairing badly corroded areas and replacing the bottom angle of the skirt where it has corroded away and is missing, AECOM estimated the cover should give another 10 years of service.
AECOM suggested a replacement cover may need to be budgeted for in the next 10 to 20 years.
Replacing the cover now would not only add significantly to the total cost of the $25 million project, but would delay completion of the project by a year or more, while the cover is ordered, fabricated and constructed on site. With the digester out of commission, remaining work on the other two digesters could not proceed without greatly compromising the treatment capacity of the plant.
The Monroe Board of Public Works voted unanimously Monday, Dec. 16, to follow the recommendation of AECOM, hired by the city to oversee the wastewater treatment plant upgrades which began in April.
Digester Cover No. 2 was installed about 1972 and has been in service for about 40 years. It was sandblasted and recoated in 1989, according to AECOM.
Construction contractors for the current facility upgrade recently removed the cover and discovered it had significant corrosion on the underside. After the steel skirt and underside of the cover had been prepped and new coating applied, Dixon Engineering Inc. did a formal assessment and identified areas of corrosion on the skirt.
The deepest pits in the skirt were measured to be 3/16-inch deep, leaving 1/16 inch of steel, about one quarter of its original thickness. Metal on the top of the cover is in good condition with no metal loss.
By repairing badly corroded areas and replacing the bottom angle of the skirt where it has corroded away and is missing, AECOM estimated the cover should give another 10 years of service.
AECOM suggested a replacement cover may need to be budgeted for in the next 10 to 20 years.
Replacing the cover now would not only add significantly to the total cost of the $25 million project, but would delay completion of the project by a year or more, while the cover is ordered, fabricated and constructed on site. With the digester out of commission, remaining work on the other two digesters could not proceed without greatly compromising the treatment capacity of the plant.