SUITABILITY OF GEOLOGICAL MEDIA FOR THE DISPOSAL OF LARGE NUMBERS OF LIVESTOCK CARCASSES IN ALBERTA: IMPLEMENTING A SITE-SELECTION PROCESS IN PREPAREDNESS FOR AN OUTBREAK OF FOREIGN ANIMAL DISEASE

The detection of a single Bovine Spongiform Encephalopathy (BSE) infected animal in May 2003 triggered a massive collapse of the beef industry in Canada, particularly in Alberta, and alerted the nation to the need to be prepared for other outbreaks of Foreign Animal Disease (FAD) in the future.

BSE is one example of a disease that may require large numbers of animals to be disposed of in a relatively short time period. The possibility of large numbers of cattle suddenly becoming non-marketable due to the BSE positive animal prompted the cattle industry and government departments to examine various options, including the disposal option. Spearheaded by Emergency Management Alberta, various agencies within provincial and federal governments convened to develop a selection process to locate acceptable sites for disposal of FAD affected animals by burial.

The AGS contributed to this initiative by providing baseline geological information that was classed according to the ability of differing geological materials to easily transmit liquid animal effluence away from a burial site. The exercise depends heavily on the power of geographic information systems (GIS) to compile and query large geological datasets to develop a four-class suitability map: suitable, unsuitable, uncertain, and no data. Components considered to be key to the selection process include: bedrock topography and morphology; occurrence of buried drift aquifers (inferred from positions of buried-channel talwegs); surficial geology; bedrock geology; and drift thickness. Numerous data sources for each of these components were assembled in digital form, and reclassified with respect to their intrinsic ability to rapidly transmit groundwater. A conceptual decision tree, rooted in groundwater protection, assisted in developing algorithms for the GIS queries in preparation of the final geological suitability map.

The geological suitability map was then integrated with other GIS datasets developed by AAFC and AFRD, to incorporate surface wetlands and steepness of surface landform slopes, both of which affect the selection of burial sites. The composite of all GIS inputs yields a burial suitability map that forms the preliminary basis for deciding where detailed investigations and field evaluations will be conducted to locate optimal sites.