Currently in the works is the interceptor project, which will be completed by Aug. 17 per the city’s contract with Minnesota-based S.J. Louis Construction, which is handling the project.
Bui said the interceptor project is making improvements to convey wastewater through the treatment plant, while mitigating water overflow from storms and floods through pipes built into the river. Currently in construction are two river crossings, at the Black Street Bridge and the Arch Street railroad crossing, where pipes will convey overflow water from the west side of the river to the east side and along the east banks to the treatment plant.
Black Street will have three pipes — two 42-inch pipes and one 18-inch pipe — crossing the river, while Arch Street will have one 16-inch pipe crossing over, Bui said. All four will join existing 60-inch pipes along the east banks of the river to bring overflow water to the wastewater plant, with a section between Arch Street and Black Street needing to be constructed.
“The extra pipes (at Black Street) are needed because there is more flow at that location,” Bui said.
The upgrades and pipe increases are needed because, currently, there is a restriction in the pipe system where during heavy rain, wastewater can get into the system and overflow into the river without being treated.
The interceptor phase costs $11.8 million, according to Bui. “Phase II” is planned to follow immediately after its completion, and will cost approximately $6.5 million to $7 million. Phase II involves the final touches on the project, more upgrades to ensure all of the water gets treated through the plant.
“Right now, some of the water isn’t getting conveyed through the plant, so this will make sure that it all gets treated,” Bui said.
The application to the EPA has already been submitted for the second phase, and construction will commence once the application is formally accepted.
“We had meetings with the EPA late last year. We submitted all of the technical documents and agreed to modify the treatment process, so we have a verbal agreement,” Bui said. “We’re waiting for a permit to install.”
The city modified the treatment process to save millions of dollars by redesigning the existing system, negating the need for a new final clarifier tank. A clarifier tank clears wastewater of sedimentation, allowing solids to settle down so that clear water flows to the final stage of treatment, which will add disinfectants to the water before it goes into the river.
“The previous (treatment process) called for a new final clarifier tank, so we reconsidered the things we can do without replacing the tank, which will save tons of money,” Bui said.
The entire sanitary sewer project is funded by the issuance of long-term bonds, sold to institutional investors, according to department officials.
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