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. |
