Live Pole Drain Systems

HEART CREEK LIVE POLE DRAIN SYSTEM

Location: Fauquier, British Columbia

Client: Pope & Talbot Forest Products Ltd., Nakusp Division

Objective: To address slope instability using a soil bioengineering system. Control seepage on the slide face by providing drainage of surface & subsurface seepage water using live pole drain systems. Reduce surface erosion and sediment input to Heart Creek.

As a result of berm construction at the toe of a slope failure area during the process of forest road de-activation, water flow was diverted into an adjacent gully. In order to avoid the potential risk of additional slope failure, the natural watercourse was restored by breaching the existing berm at the natural seepage locations.

Live pole drain (LPD) systems, which included lateral drain fascines, were installed in two natural drainage / seepage channels within the slope failure areas in the fall of 2000 and were completed during the spring of 2001. (Other structures installed at the same time are discussed in the Heart Creek project page). The central pole drains were constructed using cylindrical bundles of live cuttings, approximately 30 cm in diameter, and the lateral drain fascines using bundles of approximately 15 to 20 cm in diameter. The live cuttings used consisted of a mix of Willow species (Salix bebbiana / scouleriana / exigua), Black Cottonwood (Populus balsamifera ssp. trichocarpa), and Red-Osier Dogwood (Cornus stolonifera). These were harvested in the local area.

Due to a lack of road access, all live materials were helicopter-lifted into the site. Trench excavation for the LPD system was done manually. Upon placement in the trenches, the bundles were staked securely into place using steel “T” re-bars and back filled on either side of the bundles leaving the upper portion exposed.

This LPD system was monitored in the summer of 2001 & 2003. The site showed fully functioning live pole drain systems which were draining surface & subsurface seepage water into constructed sediment traps at the toe of the slope and good overall growth of the establishing vegetation.