Council gets report on overlay district
Situated near industry and landfills, Burnsville’s water supply is vulnerable to contamination.
A total of 1.1 billion gallons are drawn annually from a mining quarry and 2.1 billion from 17 groundwater wells in the northern and eastern parts of the city. All the sources are in the vicinity of an operating landfill, two closed landfills, a power plant, a rail line and the quarry.
“We are the poster child for the types of things that you wouldn’t typically have in a wellhead if you started from scratch,” Public Works Director Steve Albrecht said. “That doesn’t mean we can’t have a safe wellhead, but we want to make sure. That’s why we need the extra protections that some other communities may not be taking.”
Albrecht gave the City Council an annual report Aug. 8 on the Drinking Water Protection Overlay District — a large area of northern Burnsville that encompasses 783 properties and businesses.
Adopted by the council in June 2015, the ordinance creating the district authorizes officials to inspect properties to ensure proper handling of regulated chemicals that could contaminate groundwater.
Albrecht is recommending more frequent inspection of high-priority properties than the ordinance now requires and less frequent inspection of others.
Instead of inspecting all properties every two years, the city would inspect 80 high-priority properties annually, 179 medium-priority properties every three years and 524 low-priority properties every five. The council will vote on the proposal this fall.
“I think the bottom line is our water is safe to drink, and we’re making darn sure it stays that way,” Council Member Dan Kealey said.
The quarry water comes from the Kraemer Mining and Materials limestone quarry in the Minnesota River bottom. It is surface water that is discharged from the ground into a basin, where it awaits treatment.
The quarry water helps supply neighboring Savage, which gets 89 percent of its water from Burnsville. The city has inspected the water quarterly since 2011 — tests that exceed state and federal regulations — and not found contaminants, Albrecht said.
The city’s groundwater grows more vulnerable closer to the river, with the sloping ground providing an increasingly thin layer of protective soil atop the aquifer.
“We don’t have a lot of those soils down in the bottom of the bluff area,” Albrecht said. “That’s why we have to be extra diligent about what hits the surface of the ground down there to make sure that it isn’t going to get down into our wellhead.”
As long as the quarry is operating, dewatering will continue to suck groundwater away from the Freeway Landfill to the north and a related dump site, which haven’t accepted trash in decades, according to Albrecht. When dewatering ceases someday, the area’s hydrology will change.
“Our big thing is going to be getting the landfills closed” under a cleanup plan to keep buried waste from contaminating groundwater when the water table rises, Albrecht said.
Chemicals used by some area businesses also pose risks. The overlay ordinance gives the city regulatory authority over proper storage, emergency spill responses and other aspects of chemical handling.
The ordinance covers new or expanding businesses as well as existing businesses that wouldn’t otherwise be inspected. Some businesses don’t have enough chemicals on site to trigger state regulation, Albrecht said.
Seventy-eight of the 80 high-priority businesses were inspected in 2016, Albrecht said. The city already had data on the other two — the Freeway Landfill and dump site, he said.
Despite some apprehension, business owners have cooperated, Albrecht said.
“The district includes a lot of properties,” he said. “The big thing is educating. We have yet to encounter one business owner whose goal is to contaminate the water.”