Live Pole Drain Systems

AKOLKOLEX RIVER LIVE POLE DRAIN SYSTEM

Location: West Kootenay Region, Akolkolex River main road at 21 Km.

Client: Ministry of Environment, Lands, and Parks. Columbia Forest District.

Objective: To provide drainage of subsurface seepage emerging below a re-constructed road, re-vegetate and help stabilize the slope using soil bioengineering structures.

The Akolkolex road system was built approximately 25 years ago using a three quarter to full bench cut method. In the spring of 1997, a debris flow occurred at approximately km 21 along the road; as a result the road suffered a substantial failure (slump). The road was repaired in 1998 using a concrete-block retaining wall system.

Underground seepage water was found emerging from under the base of the installed retaining wall after re-construction of the road. The underground seepage water was saturating the fill slope and flowing to the toe of the slope into the river. This posed a hazard in terms of erosion and/or further slumping of this slope.

A short (15 m) live pole drain (LPD) system was installed manually in the spring of 1999 to drain seepage water from the base of the installed retaining wall to the toe of the slope and into the existing riprap adjacent to the river.

Bundles of locally collected Willow (Salix bebbiana/ scouleriana/exigua), Black Cottonwood (Populus balsamifera ssp. trichocarpa), and Red-Osier Dogwood (Cornus stolonifera) were utilized to constructed the (LPD) system.

The structure was monitored in 2000 and 2003; four years after installation. At the time the system was found to be working efficiently at draining seepage water and stabilizing the slope.