Proper Monitoring Well Abandonment (“Filling and Sealing”) is Required

The Remediation and Redevelopment (RR) Program reminds environmental consultants to follow Chapter NR 141 when abandoning groundwater monitoring wells and boreholes. If not properly abandoned, these wells or holes can pose a risk of environmental contamination.

When abandoning a monitoring well, please keep these details in mind:

  • When drilling a monitoring well, its location shall be properly mapped, surveyed and tracked as set forth in Wis. Admin. Code § NR 141.065. Wis. Admin. Code § NR 716.13 (14) lays out requirements on annual inspections during use of the monitoring wells and for the use of magnets for flush-mounted wells.
  • Permanent groundwater monitoring wells known to be constructed with an impermeable annular space seal shall be abandoned according to the requirements of Wis. Admin. Code ch. NR 141.25 (2)(d) after the protective cover pipe and ground surface seal have been removed and the well casing cut off at least 30 inches below the ground surface. The well casing may be completely removed during abandonment by pulling the well casing, overdrilling around the casing and then pulling the well casing out of the ground or by drilling out the well casing completely. If the well casing is to be removed, the well shall be sealed as the casing is removed.
  • If a well cannot be located for abandonment at the time of closure, the efforts made to locate the well must be documented and submitted to the DNR in accordance with Wis. Admin. Code § NR 726.09 (2) (h).  Documentation might include photographs of the area where the well was located. It also helps if the status of the monitoring well is checked before submitting a closure request, so that the need for a continuing obligation and the required notification of the appropriate property owner does not delay the closure review timeline.
  • Boreholes must also be properly abandoned per Wis. Admin. Code § NR 141.25 (1) (a).

If you have questions, please contact your Project Manager.

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