SYNCRUDE PROJECT

Location: Northern Alberta, Canada

Client: Syncrude Canada Ltd.

Objective: Investigate the use of soil bioengineering techniques for erosion control and site restoration at a major oil sands mining and processing facility.

Oil sands mining and processing disturb large tracts of land with the attendant potential for soil erosion and natural habitat degradation. Fine- textured marine sediments are not only highly erosive, but are also extremely saline in some cases. Polster Environmental Services Ltd. and Terra Erosion Control Ltd. were asked to investigate soil bioengineering solutions to some of the more difficult problems associated with restoration of the oil sands disturbances.

Soil bioengineering treatments are expected to be very effective in the oil sands areas of Alberta. There are abundant examples of the growth of the plants that would be used in soil bioengineering (willows, cottonwood and red-osier dogwood) in the Fort McMurray area around the mines, indicating a suitable climate for these plants. The use of live pole drains and brush layers as well as live sediment traps could be used to provide erosion protection where flows are small or intermittent. Brush mattresses as well as emergent aquatic vegetation such as sedges (Carex spp.) and Cattails (Typha latifolia) could be used where water flows are greater or to protect areas of high seasonal flows. The key to protecting the fine- textured materials from erosion is the establishment of a healthy vegetation cover. The roots will act to hold the soil in place while the above ground portions of the plants will slow the near surface flows and prevent erosive forces from eroding the soil.

Soil bioengineering treatments can be established using hand crews, thus avoiding the problems associated with machine access. This is particularly important where treatments are used to solve small erosion problems such as may be found on the tailings sand dykes. The use of hand crews also protects the small seedlings of the native plants that are establishing naturally on the disturbed sites. Soil bioengineering treatments will prevent continued erosion at these sites, will allow the natural successional processes to proceed and will re-establish native vegetation on these sites.

During the fall of 2003, an experimental trial was installed to gather quantitative and qualitative data regarding the success of the three species used in three representative sites using four different soil amendments. The trials were established in order to determine how the site will affect the growth of the cuttings. The trials were located within an approximately 80 cm layer of reclamation material composed of locally collected peat from muskeg as well as in tailing sand. The species used were native willows, cottonwood and red-osier dogwood in a brush layers technique.