As reconstruction on the retaining wall of Charman Creek near Dougall Road started in October, the contractor involved discovered soil contaminated with knotweed.
Now, a “significant volume” of soil must be removed, Town of Gibsons staff told council at a Nov. 7 meeting. The engineering team and contractor decided a shallower slope will help the crew safely replace the backfill and reconstruct the retaining wall.
Council approved a change order to the contract, for the removal and disposal of the contaminated soil not to exceed $200,000. The final total will depend on the volume of material that needs to be replaced, staff said. The contract with NB Contracting Ltd. will be amended to a revised total not to exceed $527,661. Funds are being provided by the Canada Community-Building Fund grant for the Lower Watershed Climate Adaptation through Natural Assets Project. Mayor Silas White asked staff to confirm that the costs will be covered by the grant, to which staff said yes.
Coun. Annemarie De Andrade asked about knotweed removal and expressed concern that the plant can remain dormant for decades and imbed itself deeply into the soil. Staff confirmed the soil around the site is being removed and disposed of in a licensed facility in the Lower Mainland. Both the knotweed and soil will be removed under the direction of the environmental consultants. It would be impractical and nearly impossible cost-wise, staff said, to remove the entire expanse that could include knotweed roots, and there’s a “practical limit” of what can be removed and replaced in terms of potential root contamination.
