SUPERIOR — A chance discovery late last year revealed an illicit wastewater discharge that city officials weren’t aware existed.
Now, officials in the city's Environmental Services Division have rewritten the plan for their 2023 capital projects to correct a problem that resulted in sewage being detected in a swale at the intersection of East First Street and 23rd Avenue East just north of the Osaugie Trail.
The City Council approved the new plan Tuesday, May 16, as well as a bid by Interstate Construction Inc. to partially reconstruct the sanitary sewer in the alley northeast of East Second Street and southwest of 23rd Avenue East.
Elevated levels of ammonia, indicative of urine, were discovered in the stormwater outfall that runs into the swale.
The environmental services wastewater resources team ran a total of three tests; results showed increasing levels of ammonia with each test. A sample was sent to a laboratory, which confirmed the presence of fecal coliform bacteria.
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The city’s investigation led to an 8-inch clay pipe installed in the 1880s that functioned as a combined sanitary and stormwater sewer. While a new sanitary sewer was installed in the 1930s, dye testing revealed that two of the homes in the area were still connected to the 1880s pipe. The century-old piece of infrastructure has conveyed stormwater to the swale since 2018 when the city undertook a project to address a failing pipe in the area that took stormwater to the bay.
“Some of the homes that were originally connected to the 1880s pipe were not reconnected to the new pipe,” said Erin Abramson of the Environmental Services Division. None of the drawings going back to the 1970s showed the 1880s pipe being there, she said.
Under wet weather conditions or if no one was home for an extended period, Abramson said the discovery would have been unlikely.
Staff designed the project to reconstruct the sanitary sewer by installing about 300 feet of 8-inch pipe, installing two precast manholes, removing a storm sewer manhole and reconstructing the alley.
To cover the estimated $251,000 cost of the project within budget, officials proposed using capital project contingency funds and revenue leftover from another sewer project that came in under budget this year. They also asked to forgo truck replacements for the stormwater and wastewater utilities.
Northern Interstate Construction’s bid came in under budget, as well. The South Range company proposed completing the project for about $177,373, which includes adding a larger turnaround at the dead end of the existing alley.
In other business, the council:
- Adopted a revised ordinance that requires city residents to clear public sidewalks within 24 hours of snowfall ending. Mayor Jim Paine said he’s confident the city’s code compliance officer, Lee Sandok-Baker, will be reasonable in enforcing the new requirement that shortens the timeline from 48 hours.
- Awarded the contract for sidewalk replacements to Duluth Concrete LLC at a cost of about $277,702.
- Awarded the Bardon Avenue pavement replacement project to Monarch Paving Company at a cost of about $577,699.
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