Well No. 3 rehabilitation

Work beginning August 16 at 93rd and Normandale

Well No. 3 is located near the City's Water Treatment Plant.

Beginning Monday, August 16, and continuing for approximately four weeks, Well No. 3, located at 93rd and Normandale Boulevard, will have sand removed using a procedure called “air lifting.”

Work on this project will take place during normal business hours, Monday - Friday, 7:30 a.m. to 3:30 p.m., and should have minimal neighborhood impacts.

Bloomington’s Sam H. Hobbs Drinking Water Treatment Plant receives groundwater from six deep municipal wells. The wells extend downward between 376 and 963 feet into the Jordan and Mount Simon aquifers, vast underground “lakes” in the earth’s crust. Annually, more than three billion gallons of water are drawn from these wells to meet the public’s needs. The large volume of water removed from the underground aquifers normally carries a very small amount of sand that settles in the well over time. Periodically, the sand needs to be removed to minimize wear of the pump and pipes. This is the first time since 1973, when the well was installed, that this well has undergone such a procedure.

Air lifting pushes air from a smaller pipe into a larger pipe. The bubbles and water rising to the top create a vacuum effect that lifts the sand from the bottom of the well and carries it to a large tank at the top. The air escapes through a vent atop the tank and the water/sand solution flows into a dumpster where the sand settles to the bottom and water flows out the far end. The flow of ground water from the project through the storm sewer to Nine Mile Creek is anticipated to be approximately 200 gallons per minute. The 12-inch storm sewer adjacent to the site should easily handle the flow of water and cause no flooding.

Occasionally, surging air will be used to “knock” any loose material free. Air surging is when the well is pressurized to between 100 and 200 psi and then quickly released. The fast pressure change allows loose material to fall free of the adjacent rock and then be removed by air lifting.

Noise from this process can be loud but will only happen for a few seconds.

The project has been reviewed by Bloomington’s Storm Water staff (Scott Anderson, 952-563-4867), the Minnesota State Duty Officer (Laurie, 651-649-5451), and the Minnesota Pollution Control Agency or MPCA (Chelsea Domeier, 651-757-3210). No environmental impacts are anticipated.

For more information, contact:

Jon Eaton, Water Quality Supervisor
9300 Poplar Bridge Road
PH: 952-563-4905; 952-830-8236
E-mail: jeaton@ci.bloomington.mn.us