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Bulletin 2009-37

October 21, 2009

Report on the Risk to Water Wells of Pathogens in Drilling Fluids Now Available

The Energy Resources Conservation Board (ERCB) is aware of the public concern regarding the presence of pathogenic microorganisms in surface waters used in drilling fluids and their potential impact on groundwater and/or water wells. The most common sources of surface water used in drilling fluids include dugouts, sloughs, small creeks, and beaver ponds. The ERCB retained the third-party expertise of Dr. Abimbola Abiola, microbiologist from Olds College, and Dr. Cathryn Ryan, hydrogeologist from the University of Calgary, to prepare a report on the abundance of pathogens in surface waters and evaluate whether pathogens in surface waters that are used in drilling fluids in Alberta have the ability to survive in or be transported through a groundwater system and to report their findings.

The report is a professional opinion based on an extensive review of literature and the authors’ experience and is written for a general public audience.

A summary of the key findings presented in their report is as follows:

1) The subsurface presents a hostile environment to surface water pathogens given its lower temperatures, lower oxygen levels, and fewer nutrients.
2) Pathogens can be introduced into surface waters through animal wastes, sewage, and industrial or agricultural effluents.
3) The types of pathogens typically found in Alberta surface waters are unlikely to survive the salt levels found in nontoxic drilling fluids.
4) Pathogen transport into the subsurface is unlikely, even over short distances, due to the typically low infiltration distance of drilling fluids from the wellbore.

In summary, the report indicates that the use of surface water in drilling fluid is unlikely to impact the subsurface. The Board supports this conclusion.
Report 2009-C: Risk to Water Wells of Pathogens in Drilling Fluids is available on the ERCB Web site www.ercb.ca and in print from ERCB Information Services, 640 – 5 Avenue SW, main floor; telephone: 403-297-8311; fax: 403-297-7040; e-mail: infoservices@ercb.ca. 

If you have questions about this bulletin or the pathogen report, call 403-297-8330 or send an e-mail to enviro.services@ercb.ca.

<original signed by>

Cal Hill
Acting Executive Manager
Geology, Environmental Science, and Economics Branch