British Columbia Mine Reclamation Symposium

Teck Cominco Riverbank Restoration Project : case study, Trail, British Columbia Raymond, Pierre; Smestad, Thor


Teck Cominco Metals Ltd has operated a lead-zinc smelter in Trail, British Columbia, Canada for over 100 years. A number of attempts to re-vegetate the high bank of the Columbia River below this smelter have been made; however, these have met with poor to, at best, moderate success. This project combines two essential features to re-vegetate this slope: soil bioengineering to stabilize the slope surface and the use of pioneering plants to initiate natural vegetation succession processes on the site. The primary objectives were to stabilize the site by establishing well-rooted permanent native vegetation, and to improve the aesthetics of the hillside. Other objectives were to reduce sediment delivery into the Columbia River, and to improve riparian habitat. Live cuttings used in the soil bioengineering structures were collected locally near the project area. In the spring and fall of 2006 soil bioengineering structures were installed on approximately 860 metres of the lower, active bank of the Columbia River. These consist of brush layers with protective layers and live cutting pockets installed within rip-rap, as well as brush sills and fascines within a gravel bank. The cuttings used consisted of a mixture of Salix scouleriana, S. bebbiana, S. exigua and S. lasiandra, Populus balsamifera ssp. trichocarpa and Cornus sericea. Planting was machine-assisted using excavators and survival and growth of the structures was assessed as good to excellent. The upper riverbank, or hillside site has a total width of 700 m and an average slope length of 80 m. Slope gradients range from 20 to 85% (10 to 40o) and the aspect is to the east/north-east. The slope surficial material consists of glacio-fluvial sand mixed with historical smelter waste materials such as brick and slag. The hillside units were reclaimed during the fall of 2006 and springs of 2007/08. On slope gradients greater than 40% (22 o), which is the majority of the hillside, machine-assisted planting was done using a Schaeff Walking Excavator (Spyder Hoe). On slopes greater than 60% (31o), this machine was tethered to a skidder located at the top of the slope. Materials were transported onto the slope using a skyline cable system. The soil bioengineering structures on the hillside units consist of brush layers, using a species mixture of approximately 80% Populus balsamifera ssp. trichocarpa and 20% Salix scouleriana and S. bebbiana, with a minor component of Salix lasiandra. During planting of the brush layers a custom soil amendment was utilized to increase soil fertility, retain moisture and regulate pH. Straw wattles were also installed across the slope to control surface erosion. Survival and growth of planted areas was mostly good to excellent, but with some areas of high mortality due to soil contamination and/or lack of irrigation. The hillside units were also planted with container type native shrubs and trees and hydro-seeded with native grasses using pulp mill bio solids as mulch. An irrigation system was installed and a five-year monitoring program, which includes excavation of root systems and compost tea applications, was initiated in the summer of 2007.

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