Abandoned Well Contamination Cases

1983 - Alcona County - State health department conducted an investigation following a complaint from a homeowner that water from a new well turned salty shortly after it was put into service. Before drilling a replacement well, a well drilling contractor deepened the existing 131 feet well to 356 feet in an attempt to improve well yield. Salt water under artesian pressure was encountered in a shale bedrock formation. The contractor abandoned the well and drilled a replacement well 60 feet away to the same depth as the old well. During the investigation, the contractor admitted plugging only the upper 5 feet of the old well. Removal of the cement plug revealed that a pair of long underwear had been stuffed into the well casing as a bridge for the cement. The state ordered the contractor to cement the old well from bottom to surface as required by the well code. The owner was advised that water quality was expected to improve after the plugging. The owner notified the state within a few months after the plugging and reported that the water no longer tasted salty. The salt contamination is believed to have entered the new well by moving upward in the abandoned well. The following table shows water quality before and after proper plugging of the abandoned well.


Chemical parameter Before plugging After plugging

Chloride 1693 mg/l 315 mg/l

Sodium 954 mg/l 263 mg/l

Hardness 1079 mg/l 180 mg/l

Iron 0.8 mg/l not detected

1984 - Lapeer County - Officials from the state public health and agriculture departments and the local health department conducted a joint investigation following a complaint from a farmer about decreased milk production and dairy herd illness. Coliform bacteria and iron bacteria were found in the new well. Two old abandoned wells (110 and 120 feet deep) were found on the site. The farmer was advised to plug them before proceeding with further redisinfection of the new well. While preparing one of the wells for cementing, it was found that gray water from the basement laundry in the farmhouse drained into the well. Improper sewage disposal into the well was a likely source of the well contamination.


1987 - Alpena County - MDNR officials determined that a private residential well became contaminated from illegal disposal of waste into an abandoned dug well. The property owners used the old well to dispose of household trash, including old oil cans. The old well was 30 to 40 feet away from their water supply well. The contaminants found in their drinking water included benzene, toluene, xylene, and other hydrocarbons.


1988 - Eaton County - The state and local health departments investigated the bacteriological contamination of a residential well. The house was for sale and contamination was discovered when water samples were collected by the local health department as part of an evaluation requested by the realtor. The 105 feet deep well contained high levels of coliform bacteria and several attempts to disinfect the well with chlorine were unsuccessful. Water tests from five surrounding homes in the subdivision were negative. The interior of the well was inspected using a downhole camera and no defects were found. A state health department investigator contacted the person who owned the land at the time it was subdivided and found that the contaminated well was located in the vicinity of an abandoned dug well that once served the farm. The unplugged well may have contributed to the contamination. The contaminated well was plugged and a successful replacement well was drilled about 50 feet away.


1988 - Grand Traverse County - A water well contractor improperly capped an unsuccessful well drilled at a campground. A campground employee later observed a camper preparing to dump the sewage holding tank from his travel trailer into the well. The well was 185 feet deep and the water level within the well was about 90 feet. The state health department ordered the well properly sealed and a replacement well was drilled. The state initiated action to revoke the contractors certificate of registration as a result of this incident and other code violations. The case was settled with the contractor entering into a Consent Agreement which included payment of a $2000 penalty and a one year probation. Although this incident did not involve ground water contamination, it illustrates the potential threat posed by unplugged abandoned wells.


1989 - Genesee County - A state health department official investigated a complaint of unpleasant taste and odor from water obtained from a private well. The change in taste and odor occurred about a year after completion of a replacement well. Several unsuccessful attempts had been made to disinfect the well with chlorine. Water sampling revealed contamination with Pseudomonas bacteria. These bacteria are secondary pathogens commonly found in soil. The investigator found that the old 2 inch abandoned well was never plugged. It had been capped and buried in the old well pit. The homeowner was instructed to excavate and plug the abandoned well. After plugging of the well, the replacement well was chemically treated. Follow-up sampling showed negative results and elimination of the taste and odor.


1992 - Wayne County - MDEQ officials found that gasoline or oil had been poured into one of three unplugged abandoned production wells at a defunct oil refinery. The 12 inch diameter bedrock wells ranged in depth from 126 to 335 feet and were abandoned in 1992. After raw product was bailed out, 4000 gallons of water was purged from the well. Analysis of a highly diluted sample showed 855 ppb benzene in the ground water. The impacted ground water will be delineated vertically and horizontally in the future.


1992 - Manistee County - A plume of corrosive, contaminated ground water moving in a surficial aquifer, crossed corporate property lines from a Superfund site to an adjoining property. The "black liquor " contaminant migrated into at least two other deeper aquifers. Movement was aided by numerous abandoned and poorly maintained brine wells and water wells. Company employees, who routinely used well water (from the lower aquifer) for drinking purposes, alerted corporate officials of the problem. It was determined that many of the old well casings had corroded at the upper aquifer interface and allowed the contamination to migrate to the lower formations. The drinking water wells serving this major industrial complex and all old well casings were required to be properly plugged. The responsible party was required, through court action, to pay for the replacement of neighboring water supplies. This involved installing a specially designed water line approximately one mile under a lake.


1993 - Jackson County - State health department officials investigated the accidental plugging of a large volume production well at a state correctional facility. The case demonstrates the existence of a hydraulic connection in the sandstone bedrock between the production well and a nearby abandoned test well and illustrates the contamination threat posed by unplugged abandoned wells. The abandoned test well was about 300 feet deep and located 11 feet away from the production well. The test well casing terminated flush with ground surface and had a steel plate cover spot welded to the casing pipe. The well drilling contractor reported observing ponded surface water being drawn into the test well when the production well's pump turned on. The production well had positive coliform bacterial contamination afterwards. While plugging the abandoned test well, cement inadvertently traveled horizontally and plugged the production well. A new well was constructed.


1997 - Bay County - Vandals overturned a fuel oil tank at a home causing about 110 gallons of fuel to spill on the ground. While excavating contaminated soil, the remediation contractor uncovered an old 12 inch diameter, 65 feet deep dug well. The loose fitting concrete cover was buried under 2 feet of soil. The well terminated at the top of the bedrock. The well had been abandoned when the home was connected to municipal water about 10 years ago. An open annulus was present between the well casing and the borehole wall. Fuel oil was found floating on the water within the well about 10 feet below surface. It was estimated that 4 to 5 gallons of fuel entered the well. The well contamination was cleaned up and the well was plugged its entire length with concrete.



1/98 -WCU