An Estimation of Surface Excavations in Alberta
Recent land use simulations (ALCES, 2012) and ABMI Land Use Footprint data (2010) independently estimate the abundance (area, edge, count) and distribution of small surface excavations in Alberta. These excavations take many forms, and include gravel pits, borrow pits, dugouts, lagoons, and landfills. Better known are the larger excavations associated with the coal and bitumen sectors. These surface excavations provide hydrocarbons (coal, oilsands) as energy feedstocks, construction materials (fine-textured fill, sand, and gravel from gravel pits and borrow pits) required to build infrastructure (roads, buildings), provision of water to livestock (watering holes), or storage and treatment of solid and liquid wastes (landfills, lagoons).
Surface mining footprints associated with extraction of bitumen and coal are generally well understood by Albertans, as is their positive and negative effects on a suite of social, economic and environmental indicators (Nikiforuk, 2009). In contrast, the role, consequences, and cumulative effects of other surface excavations are relatively unknown to the general public. Furthermore, the scientific community, municipal and provincial planners, and those in the political arena, are largely unaware of the collective importance and magnitude of these land use footprints. Part of the issue is that these features are individually small, and hence often escape public attention and dialogue. In reality, environmental issues relating to surface excavations are many and involve changes in movement of water and pollutants, and changes to plant and wildlife community structure.
To underscore the economic and political importance of these surface excavations, imagine the outcry in Alberta that would most certainly occur if these landuse features were removed or disabled. Where would we water our livestock, where would we get gravel for road construction and home foundations, and where would we place our human waste (fluid, solid) for storage or treatment? Clearly, society understands the end-user benefits of these features, but do they understand how common these landuse footprints are, how much land they consume, and what effects they have on key environmental processes such as water quality and quantity.
The successful implementation of community-based watershed groups and the Alberta Land Use Framework require an in-depth understanding of the full suite of landuse footprints that have shaped our landscapes and will transform them in the decades to come. These public initiatives have made some good progress but will need to broaden their discussions to include surface excavations if they wish to address the full extent of concerns expressed by the stakeholder community. During the past decade, several watershed groups and individual citizens who were concerned about the potential adverse environmental effects of surface excavations approached the ALCES Group. These organizations requested of the ALCES Group useful information through which they can make informed decisions, or at least participate in an informed discussion.
This project represents a preliminary effort to assess the magnitude, distribution, area, and frequency of different surface excavations in Alberta. Our analyses focused on those surface excavations that are less well known. We learned that the ABMI 2010 Land Use Footprint dataset is an invaluable source of spatial data and can assist the discussion about current land use footprint on the provincial landscape. Based on a modest field validation effort for gravel pits, ABMI datasets did a reasonably good job of correctly classifying these features. We also learned that systems-based simulation models could do a very reasonable job of estimating metrics of surface excavations. These analyses are intended as a start, and not the end, of an important dialogue relating to surface excavations that create both benefits and liabilities to Albertans.