Groundwater is water that slowly soaks into the ground from rain, snowmelt or surface water and is stored in the tiny pore spaces between sediment grains or in fractures within rock layers. There are more than five productive groundwater zones, or aquifers, monitored at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, ranging from several feet deep to more than 1,000 feet deep.
The aquifers within bedrock, at least 60 feet deep at Fermilab, are classified by the state of Illinois as potable resource aquifers and are subject to more stringent protective quality standards. Several of these aquifers intersect and interact with Fermilab’s subsurface accelerator and detector enclosures.
Most subsurface enclosures at Fermilab use sumps to drain groundwater from around the structures and pump it directly to the industrial cooling water pond system. But the NuMI portion of the accelerator structures sits within bedrock and uses a drainage system to draw groundwater flow toward the tunnel, “capturing” any groundwater that could be potentially activated. That captured groundwater is then pumped into the piping portion of the ICW system. Future structures, such as PIP-II and LBNF, will be built with groundwater management lessons incorporated into their design.
Fermilab follows U.S. Department of Energy and U.S. Environmental Protection Agency regulations for monitoring the quality of groundwater and state rules for reporting water and groundwater use. There are more than 120 wells across the lab, with most used for flow direction and quality monitoring, but some are used for supply.
Groundwater at Fermilab provides a range of supply, from the bison barn to supplementing the ICW system (routinely from NuMI and occasionally from a deep well when needed). In the past, on-site groundwater was used for Fermilab’s drinking water, but now the lab purchases potable water from adjacent municipal systems that draw from a mix of Lake Michigan water and groundwater.
Chris Greer is an environmental specialist in Fermilab’s Environmental Protection Department.