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MADISON – The boom in Wisconsin frac sand mining is driving additional demand for exploratory drilling around the state, and this is elevating the potential for serious groundwater contamination.
Groundwater and enforcement specialists with the state Department of Natural Resources are aware of several cases in which boreholes drilled by landowners and others have not been sealed or sealed properly. This creates a direct pathway for potential contaminants to reach groundwater resources.
“There are landowners and drillers out there who take the time to understand state law and do the work properly,” said DNR Secretary Cathy Stepp. “Our concern is with a smaller number of irresponsible parties who threaten our groundwater resources. We need individuals searching for sand deposits to do it responsibly.”
If a landowner authorizes drilling, Stepp said, the landowner should ask the driller to properly seal the bore hole.
The DNR is reminding individuals involved in sand drilling that state law requires the proper abandonment of all boreholes or drill holes exceeding 10 feet in depth or any borehole that intersects groundwater.
This message is affirmed by the newly formed Wisconsin Industrial Sand Association – whose members include U.S. Silica, Unimin, the Wisconsin Industrial Sand Company, a subsidiary of Fairmount Minerals, and Badger Mining Corporation. WISA promotes safe and environmentally responsible mining and has established a code of conduct for members to follow.
“The members of the Wisconsin Industrial Sand Association adhere to very high environmental and safety standards, and we applaud the DNR’s efforts to ensure all operators do, as well,” said Rich Budinger, president of WISA. “Sand mining offers significant economic benefits for Wisconsin when done responsibly. We support this effort by the DNR.”
State law requires drillers to file a report upon abandonment. Improper abandonment could result in enforcement action.
While the code specifies that a bore hole be properly abandoned within three days of its use being discontinued, DNR encourages drillers to close exploration boreholes immediately to avoid the potential for soils collapse and bridging to occur in the hole.
“Most drinking water wells, with very few exceptions, are recharged locally,” said DNR drinking and groundwater supervisor Mike Blodgett. “Failure to fill these boreholes properly can have a very direct impact on local drinking water supplies.”
Rules for properly abandoning drill holes are in NR 141.25, Wisconsin Administrative Code. Leaving holes open can create a direct conduit for entry of contaminants to waters of the state and is a violation of Chapter 281, Wisconsin Statutes.
- State law defines a borehole as “a circular hole deeper than it is wide, constructed in earth material for the purpose of either installing a well or obtaining geologic or groundwater related data.” Boreholes are also referred to as drill holes.
- State code NR 141 addresses sealing requirements for boreholes and groundwater monitoring wells. It states, among other requirements, that “boreholes and groundwater monitoring wells shall be abandoned by complete filling with neat cement grout, bentonite-cement grout, sand-cement grout, concrete or bentonite-sand slurry.”
A link to NR 141.25 can be found on the Silica sand mining pages of the DNR website along with a form to be submitted to the local DNR office after abandonment. Information on WISA is at wisconsinsand.org.