The very big rain that dropped 3½ inches of rain on downtown Grand Marais on July 18, 2013 flooded the Cook County Whole Foods Co-op parking lot once again and overloaded the city’s sanitary sewer.
At a Public Utilities Commission meeting on July 24, Water/ Wastewater Superintendent Tom Nelson reported that the city’s system cannot handle rains this big. The system’s peak sustainable flow is one million gallons, and this storm sent 3½-4 million gallons through the wastewater treatment plant.
A significant amount of grit and rock, some fist-sized, entered the system because of the strong flow of water. Rocks are bad for the system, Nelson said, and need to be removed. “That’s why we clean and televise [the underground pipes],” he said. Some of the “rocks” that entered the system might have been decayed bricks originally lining the system.
Water/Wastewater Department personnel shoveled 25 buckets of grit out of one spot.
The city’s storm sewers are separate from the sanitary sewer system and are maintained by the Streets Department. Storm water is collected in the pond behind the Co-op and above the municipal pool. Rainwater still enters the sanitary system, however, through cracks.
Pumps helped deal with the extra flow, but if the electricity were to go out, handling the extra water could be a problem. If that happened, the city could call for mutual aid from another municipality that has portable generators.
While the pipes underneath downtown Grand Marais are new, the system throughout the city could use renovation, Nelson said. “Anything we can do is going to help,” he said.
“I’m sure the lines are clean right now!” Nelson said.
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