Installation of Vegetated Riprap

TECK COMINCO METALS LTD RIVERBANK RESTORATION PROJECT

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Riverbank Section 1

Riverbank Sections 2 and 1A

Survival and Growth

Main Riverbank Restoration Project Page

Location: Bank of Columbia River adjacent to the Teck Cominco lead-zinc smelter in Trail, BC

Client: Teck Cominco Metals Limited

Objective: Creation of fish and wildlife habitat by establishing vegetation within riprap revetment during road construction.

The live cuttings used in the vegetated riprap applications described below consisted of the following willow species (Salix bebbiana/scouleriana/exigua) and (Salix lucida ssp. lasiandra). Black Cottonwood (Populus balsamifera ssp. trichocarpa) and Red-Osier Dogwood (Cornus stolonifera).

Riverbank Section 1:

In the installation of Section 1, live cutting pockets and a vegetated riprap brush layer technique were used.

A riprap toe apron was first constructed within the river to support the additional riprap placed on the bank above. A gravel layer was placed over the original excavated bank in order to provide filtration of fine sediment from entering the river. The first lift or layer of riprap was then placed and live cutting pockets were inserted into the bank above using an excavator and manual labour.

Each pocket consisted of six cuttings contained within two protective sleeves, slit to allow future expansion as stems grow. For each pocket the excavator opened a planting hole, into which the base of the cuttings were placed manually along with water and custom soil amendments. The plastic sleeves were positioned so that the cuttings were protected when the next lift of riprap was placed above. A total of four rows of live cutting pockets were installed. A final lift of riprap was placed above the highest rows. The elevation of each row of pockets was maintained using a laser level as work progressed.

To construct the vegetated riprap brush layer, a trench was dug into the road sub-grade behind the last lift of riprap. Live cuttings were laid out along this trench so that the tips protruded above the adjacent riprap. Water, topsoil and soil amendments were added prior to backfilling of the trench using native soil material. Protective wooden boards/sheets were then placed over the lower portion of the exposed cuttings as protection and final rock was placed to raise the road to the desired sub-grade.