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Anthropogenic Impacts on Groundwater and Slope Stability; a Case History


April 21 @ 12 PM

A. W. Clifton,

Clifton Associates Ltd, Regina, SK, Canada

Chris Bunce

CP Rail, Calgary, AB, Canada

The CP Rail track between Fort Steele and Cranbrook BC (the Cranbrook Subdivision) was relocated along the valley of the St Mary’s River prior to 1975 to accommodate construction of dams on the Columbia River.  The chosen route for the track traversed well-drained glaciated terrain characterized by a drumlinized till plain interspersed with glacio-fluvial and glacio-lacustrine deposits between Mile (MI) 98 and about MI 99.5 where bedrock outcropped at track level.  At the time of railway construction, the valley wall was well drained with no obvious signs of seepage or other evidence of groundwater; in fact, a dominant landform were silt “hoodoos” that can only exist when the silty soils are dry.


This was not the only construction in the area.  A municipal wastewater pond was constructed about 3 km distant from the tracks in the vicinity of MI 99.  The pond was permitted by the regulatory agencies on the condition that it would have “zero leakage”.  A grouted cutoff wall was constructed across a known gravel channel to contain any potential seepage.   The pond was commissioned into service in 1981.


The track performed without notable defects except for a small landslide in the vicinity of MI 98.7 in May 1981. Major landslides occurred in the vicinity of MI 99.05 and MI 99.25 in March and May 1997, followed by similar major slides between MI 99.05 and 99.25 during March and June 2007. 

This paper outlines the substantial and complex investigations undertaken to demonstrate the connection between operation of the wastewater ponds and instability of the railway embankments.  It also explores the value of a multidisciplinary approach, coupling geological, geotechnical, hydrogeological, geophysical and geochemistry skills to evaluate human impacts on the physical and geotechnical environments

Wayne Clifton MSc DSc PEng

Wayne Clifton founded and grew Clifton Engineering Group from a four-person start-up in Regina to one of the largest independently-owned engineering firms in Western Canada. Committed to building healthy communities and contributing to the economic vibrancy of the region with a focus on honesty, integrity and safety, his life work set a new standard for professional engineering.

Wayne has spent more than 40 years as a specialist geotechnical engineer, consulting on thousands of geotechnical and environmental projects both regionally, nationally and internationally. He provided the geotechnical and environmental design for SaskPower’s Poplar River Generating Station and also served as the geotechnical, environmental, and materials consultant for the design and construction of Shand Power Station. Recent assignments include acting as the geotechnical lead on CP’s Belle Plaine Spur construction across the Qu’Appelle Valley, the North Commuter Parkway Project in Saskatoon, SK, and the CN Bridge replacement on the South Saskatchewan River near Warman, SK.  He has been called on by major corporations and provincial and federal governments to assist with developing environmental policies, regulations, and codes. Wayne contributed to the implementation of Saskatchewan’s Environmental Code and to policy development in areas of groundwater management, land use classification, and waste management.

Wayne’s leadership roles in industry associations include past chair of ACEC-SK, past president of APEGS, and director of ACEC-Canada. Among other achievements, he has received the Beaubien Lifetime Achievement Award; G. Geoffry Meyerhof award and the R.F Legget Medal. Wayne has authored or co-authored hundreds of publications in technical journals and has served as an adjunct professor at the University of Saskatchewan and the University of Regina.

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