Live Pole Drain Systems

BEAVER CREEK LIVE POLE DRAINS

Location:  Aurora Inter-site Pipeline right-of way at Beaver Creek, near Fort McMurray, Alberta.

Client: Syncrude Canada Limited

Objective: To restore stability of slope slumping/failures site using soil bioengineering structures and to provide drainage of surface & subsurface seepage water using live pole drain systems.

In 2004, 2005 and 2007 Terra Erosion Control installed live pole drain (LPD) systems at the Beaver Creek site. This project consisted of three phases: I, II, III.

In October 2004, LPD systems were installed to drain excess surface and seepage water off a bench area within the pipeline right-of-way. Initially the water caused soil slumping/failures down slope on steeper area of the right-of-way. The LPD systems were constructed to drain this water into a bordering forested area.

The LPD systems consisted of four central pole drains structures, each approximately 70 to 80 meters in length with lateral drain fascines of approximately 4 to 5 metres. The central pole drains were constructed using cylindrical bundles of live cuttings of approximately 30 cm in diameter and using lateral drain fascines bundles of approximately 15 to 20 cm in diameter.

The trenches were dug using a small excavator at a slope gradient of 2-3% to allow drainage. Other treatments were applied to the site in between structures such as muskeg (organic mulch) and native grass seed.

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). The structures were secured using wooden stakes.

These LPD systems have been very effective at draining excess water off the pipeline right-of-way into the adjacent forested area. The outlets of the central pole drain structures were installed in a staggered pattern (i.e. different locations to spread water outflow over a larger area). Due to the lay of the land, the drained water gathered in a receiving area away from the right away and created a small slide during the spring of 2005. This small failure was also stabilized using a LPD system in the fall of 2005 (see Phase II structure).

Note also that sections of the LPD structures installed in 2004 were destroyed in the spring of 2007 during repairs of the pipeline and re-constructed in the fall of 2007.

To see a complete description of the project see the link for Syncrude Canada Beaver Creek Project Phase I, II, III.