What's under your landfill?

How water moves around and through the Rock County Demolition Debris Landfill will receive an in-depth look as required by the state’s permit renewal process.
County commissioners recently hired Melanie Niday, a hydrogeologist with Short Elliot Henderson Inc., St. Cloud, for $13,450.
Niday will evaluate the current groundwater-monitoring plan in cooperation with Minnesota Pollution Control Agency (MPCA) officials to renew the facility’s use permit.
The Rock County Land Management Office submitted paperwork for its permit renewal in March 2009. The state, however, waited until earlier this year to request more information as part of the permit process.
 
State officials changing opinion on landfills
“The state is going through a thought process with demolition landfills to make sure things are working,” said Niday, who has worked as a hydrogeologist for 27 years. “Today’s landfills are very different than they were 30 years ago.”
In the past decade MPCA officials have been studying what is occurring underneath demolition landfills and how effective clay-based facilities are at protecting water supplies.
While no new regulations have stemmed from the MPCA’s concerns, the closer look has slowed the permit renewal process.
Rock County continues to operate under a permit that expired six years ago and will do so until it is renewed.
Niday said Rock County’s clay-based facility is inert and has provided sufficient protection to the water supply since it was first permitted in 1998.
She is examining decades-old water sampling results and comparing them to current samples. There hasn’t been any significant change.
“The clay soil absorbs some of the contaminants,” she said. “I don’t expect to find any problems.”
Niday and local staff have reviewed a preliminary permit draft and the state is also requesting additional test wells.
Niday said she is advocating for one new testing well (at a cost of $3,000 to $5,000) at the demolition site, bringing the total to three. She will also advocate sampling those wells twice a year instead of three.
The goal is to reduce the landfill’s future operating costs and “meet that happy medium where everything makes sense” between the parties involved, she said.
 
About the landfill
The Rock County Demolition Debris Landfill was originally permitted by the MPCA in 1998.
“The purpose of the demolition landfill is not to make money but to provide a service to the community,” Niday explained.
The demolition landfill gives residents a place to deposit debris from construction projects or from natural disasters.
Niday said having an adequate place to bring materials has eliminated the burning and burial of debris on private land throughout the state.
Possible leaching in demolition landfills is the primary concern from MPCA officials.
Rock County’s demolition landfill is constructed with a clay base, which acts as a natural filter to retain surface water and allows it to slowly penetrate though the clay soils. Some officials think a plastic liner and not clay is the only safe protection for the environment.
Niday disagrees.
By examining previous water tests, she said she would be able to prove that Rock County’s clay liner and current practices (such as banning materials like treated lumber) are effective protection for the area’s groundwater.
Niday expects to finalize her report in February 2016.