Its been several years since the Grand Marais Public Utilities Commission (PUC) has had the sewer lines cleaned, but Tom Nelson, water/ wastewater superintendent, is in the process of seeking bids to see that this work will be done this summer.
Nelson told PUC members on Wednesday, April 20 that he was seeking quotes for cleaning and televising approximately 1,600 feet of sewer main. Most of those mains, said Nelson, are made of 8-inch clay tile.
“There will be a need for root cutting and the cutting of protruding service laterals,” Nelson said. Most laterals are iron pipe. Hopefully the work will be done by August 1, he said.
Because of the Minnesota Pollution Control Agency’s (MPCA) new requirement for lowering mercury in treated water, the Grand Marais waste treatment facility needs to be upgraded.
To that end, Nelson has prepared a request seeking a qualified engineering firm that has a proven track record in designing and improving wastewater treatment plants with a special focus on removing mercury.
“The selected firm will perform a Facility Plan and Design that addresses improvements to the wastewater treatment facility necessary to bring effluent into compliance with the National Pollution Discharge Elimination System (NPDES),” said Nelson.
NPDES permits establish limits and conditions for discharges from municipal wastewater treatment facilities for the entire country.
The new regulations call for mercury levels not to exceed 1.8 nanogram per liter (ng/l) per monthly calendar average. How small is that? According to Nelson, 1.8 ng of mercury in the water is like one sheet of standard typing paper compared to the surface area of the county. Or, he said, “It’s like one ounce in 7.5 billion gallons of water.”
It will also take into consideration future growth of the area and “give consideration for anticipated regulatory changes and energy conservation potential,” he said.
The last time the Grand Marais waster water treatment plant was improved was 1988. At that time it was designed to handle 3,800 people in the summer/fall and 1,950 in the winter. The plan was to run until 2009 and then be looked at for revision, so it has worked well up until now.
Currently the city operates an extended aeration oxidation ditch used to treat sludge and process it for waste. Chemicals are added to remove phosphorous and ultraviolet rays from the sun are used to help with disinfection. Liquid biosolids from the sludge are hauled to the Western Lake Superior Sanitary District.
Once a Facility Draft has been completed for review, a public meeting will be held and a final report for the MPCA for approval will be submitted.
Nelson said the city would submit a study, and ultimately a facilities plan, for MPCA and the Minnesota Public Facilities Authority for funding consideration in accordance with the Clean Water Funding submittal dates.
Future design and construction timelines will be based on recommended solutions and project funding considerations with expectations that final plans and specifications for any required upgrades will be submitted to MPCA by March 1, 2017, said Nelson.
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