Environmental Monitoring and Research

Update on the Bioengineering Techniques for Revegetation of Riparian Areas at the Colomac Mine, NT: Seven Years Later

Thursday, November 22, 2018 - 09:20 to 09:39 Theatre 3


M. Hewitt (Presenting)
Flat River Consulting

A. Richardson
Contaminents and Remediation Division, CIRNAC

Factors such as nutrient poor soils, harsh climate, remote locations, and high costs make revegetating disturbed areas in northern environments a challenge. A case study is presented where innovative bioengineering and project planning techniques were employed to revegetate and remediate three riparian areas at Colomac Mine, an abandoned gold mine 220 km north of Yellowknife, NT. The revegetation plan focused on establishing pioneer species and facilitating natural recovery and succession. A “rough and loose” technique was used to allow the soil to capture and retain moisture, trap windborne seed, promote easy root penetration and prevent erosion. Harvesting and planting local willow cuttings (Salix sp.), alder (Alnus viridis) seeds, and sedge plugs ensured that the vegetation planted at these sites was adapted to local climate and soils. Monitoring included vegetation counts, percent vegetation cover and photographic documentation. After seven years, vegetation cover was 80% to 100% where bioengineering techniques were used, and there was no further loss of the plants and cuttings that had survived during the first two years. Dense thickets of alder were growing in drier areas. Fifty five plant species not planted have germinated. The bioengineering techniques implemented provided a successful, cost effective, and local approach to revegetation.