AUDIENCE: legislators/governmental officials/environmental agencies/water well industry/oil and gar industry/general public

BACKGROUND: Direct contamination of ground water and cross contamination of aquifers have been documented throughout the United States. One potential ground water contamination source is abandoned wells and boreholes which penetrate aquifers or which breach a zone that provides a significant barrier to contaminant migration. Cross contamination may occur in abandoned wells or boreholes when two or more aquifers are penetrated and a seal has not been placed or is no longer intact between the zones to prevent the water from mixing. The potential for direct ground water contamination exists in abandoned wells and boreholes along the borehole if an adequate surface seal was not installed orginally or if it has deteriorated.

The majority of state have regulations specifying plugging methods for abandoned water wells, but these regulations may not encompass all wells or boreholes of concern. Difficulty also arises in locating abandoned wells and boreholes and then encouraging the owner to properly address the structure and pay for the work. Since more than half of the U.S. population uses ground water as its drinking water supply source, this situation should be addressed.

ISSUE: What should be done about abandoned wells and boreholes which penetrate aquifers or breach a zone that provides a significant barrier to contaminant migration?

It is the position of the National Ground Water Association (NGWA) that all abandoned wells and boreholes which penetrate aquifers or breach a zone that provides a significant barrier to contaminant migration should be decommissioned. By decommissioning it is meant that such wells and boreholes must be plugged so as to prevent any contamination from entering or circulating within or leaving such structures. Wells and boreholes which have been modified to serve a new and approved purpose, such as water level monitoring, or which have been temporarily capped and maintained on an inactive basis are exceptions to this assertion.

State regulations or applicable industry standards should be followed in plugging operations. The goal of plugging abandoned wells or boreholes is to restore the hydrogeologic characterisitics of hte site and prevent the abandoned well or borehole from being a potential conduit for surface contamination or cross contamination of the aquifer.

Abandoned wells or boreholes for purposes of this issue brief are those that have permanently ceased to serve any useful purpose or are in such a state of disrepair that their original purpose cannot be reasonably achieved. Examples of wells or boreholes that should be properly plugged if they are abandoned and if they penetrate an aquifer or breach a zone that provides a significant barrier to contaminant migration include water wells; monitoring wells; oil and gas wells; cathodic protection wells; exploration boreholes drilled for oil and gas, mineral, geothermal, geological, geotechnical, or geophysical purposes and blast holes.

NGWA recommends further that a well completion or decommissioning report for each of the above-named wells or boreholes be submitted to an appropriate state agency or its designated local agency following construction or decommissioning. Well owners should be held responsible and penalized for failure to decommission abandoned wells or boreholes in a timely and proper manner.

Regulations regarding proper decommissioning procedures and materials should be promulgated by an appropriate state agency along with meaningful enforcement powers. The state agency should work with local ground water industry members and consult applicable industry standards in developing regulations to minimize costs while promoting effective ground water protection.

All existing abandoned wells or boreholes should be decommissioned. Because of problems in discovering and determining ownership of these structures, public education regarding abandoned wells and boreholes is an important part of achieveing compliance with any state requirements.

CONTACT: Christine Reimer, NGWA, 800/ 551-7379

REFERENCE: Drafted by William Nork April 1, 1991 -- approved without change by Ground Water Protection and Management Committee on October 31, 1991; presented to AGWSE Board of Directors and approved with substitution of decommissioning for extirpation on February 28, 1992, submitted to NGWA Board of Directors for permission to publish for member comment on April 10, 1992; revised based on member comment September 1, 1992; submitted for NGWA Board of Directors review on September 28, 1992; and approved for final adoption by NGWA Board of Directors on December 18, 1992.