Reclamation of Contaminated Lands Adjacent to Lead-Zinc Smelter

COMINCO DUNCAN SLOPE PHASE III and IV

Link to:

Phase I and II

Location: Adjacent to Lead-Zinc Smelter in Trail, BC

Client: Teck Cominco Metals Limited

Objective: Reclaim contaminated land adjacent to lead-zinc smelter by capping with soil suitable for plant growth. Control accelerated soil erosion and establishment of native vegetation.

The Duncan Slope Phase III and IV project area covers approximately 1 ha. The site is located immediately adjacent to the Phase I and II project area and was therefore subjected to similar levels of sulphur fumigation and metal depositions from the smelter. In 2005 Terra Erosion Control Limited was retained to develop and implement a reclamation prescription for this area. Katherine A. Enns, RPBio., M.Sc., PBiol., Delphinium Holdings Inc., collaborated in development of the planting prescription and is using this area as a research site.

In March 2006 a sandy-loam soil capping material was placed to a depth of approximately one meter over the Phase III area. Prior to soil spreading, lime was applied to the site to ameliorate the highly acidic native soil condition.

Composted biosolids from the Celgar pulp mill in Castlegar was used as an organic amendment in the soil capping material applied to the top 0.3 meters. The quantity of biosolids used was calculated so as to obtain 7.5 % organic matter in this surface layer.

After soil placement using a small bulldozer, the machine tracked up and down the slope to create cleat marks (surface roughness) for seed microsites and rain catchment. Straw wattles were also installed across the slope to control surface erosion until grasses became established. The site was seeded with native grasses, using both bunch forming and sod forming species, along with legumes. The seed mix was developed by Dave Polster R.P.Bio of Polster Environmental Services Ltd.

Phase IV, which was simply the completion of a small area not finished in March (Phase III), was completed in October 2006.

A variety of native coniferous, deciduous trees and shrubs were planted in the fall of 2006. Grass/brush mats were installed around seedlings during planting to help reduce grass competition.

During the composting process the biosolids used on this project became heavily infested with weed seeds (windrows were not covered). This resulted in heavy weed growth on the site, necessitating an intensive hand weeding treatment in June 2006.

Grass cover was very good in the spring of 2007, which effectively stopped soil erosion from the site. Survival of the planted seedlings was, however, very poor.