Park Board to divert apartment discharge into Calhoun

For the second year, a pipe will carry warm groundwater away from the lagoon between Lake Calhoun and Lake of the Isles

Warm water being pumped from beneath a luxury apartment building opened a hole in the lagoon ice in December. Credit: Dylan Thomas

EAST ISLES — The Park Board once again plans to divert warm water being pumped into a city storm sewer away from the lagoon between Lake Calhoun and Lake of the Isles.

A flexible pipe will carry the water to Lake Calhoun and away from the lagoon, where thin ice and open water pose a hazard to walkers and cross-country skiers. The warm water is being pumped into the city storm sewer from the basement of a luxury apartment building whose owners are being sued by the city.

That lawsuit against the owners of 1800 Lake on Calhoun was filed Dec. 23, three months after a city deadline to resolve the issue passed. The ground floor of the building’s two-story underground parking garage lies as much as 18 feet below the water table and has required constant dewatering since construction in 2011.

While the developers, Nick Walton and Daniel Oberpriller, were granted a temporary dewatering permit during construction, they never applied for or received a permit to continue. The city calculates pumps are removing 170 gallons of ground water per minute from the basement. That 55-degree water enters the city storm sewer and is discharged through a pipe into the lagoon.

Walton and Oberpriller at one point offered to dig an injection well to pump water back into the aquifer, but that solution was rejected by the city.

“The ongoing unauthorized discharge of groundwater into our storm sewers, and ultimately the Chain of Lakes, affects water quality and harms the environment,” Bridgette Bornstein, the city’s deputy communications director, wrote in a statement regarding the lawsuit. “It’s also a safety hazard in the winter, when the warmer water causes ice to melt on the lagoon. For these reasons, we’re asking the property owner to stop putting groundwater into our storm sewers.”

In a Jan. 3 email property manager Lynn Wyffels said the owners planned to “work diligently” with the city, their own engineers and other experts “to come up with a mutually acceptable solution.”

Wyffels didn’t respond when asked if the owners were planning to test or implement a specific mitigation plan. A range of options was outlined in a 2013 Barr Engineering report, several with price tags reaching into the millions.

The Park Board installed a pipe to divert the water last winter, too. It will carry the water to an area near the north shoreline of Lake Calhoun, and is expected to be completed by Jan. 16.