During the construction of the Intalco Aluminum Corporation plant in the late 1960s through operations into the early 1970s, construction debris and other wastes were deposited in three ravines along the bluffs of the Georgia Strait shoreline.  At several locations, steep 180-foot-high bluffs flank the western portion of the property adjacent to the strait.  Over time, the waste material and native materials, within the ravines and along the bluffs, have gone through cycles of unstable conditions.  As a result of this dynamic environment, waste and native material from two of the three landfills (BI and BII) frequently migrated to beach areas.  The third landfill (CCDL) is set back from the shoreline, and therefore, it did not directly affect the adjacent beach.  In addition to addressing these physical impacts, all three landfills needed to meet stringent surface water discharge standards for protection of aquatic life.  Anchor was engaged in the project to develop a remedy achieving three main goals–prevent impacts to the beach areas from migrating waste, provide a long-term solution to the slope instabilities occurring within the ravines, and prevent impacts to surface water from stormwater infiltration and transport through the landfill deposits.

To address the issues associated with BI and BII, Anchor QEA designed an excavation and revegetation plan to restore the two ravines to natural conditions.  The goal is to remove all waste deposited within the landfills and return the area to a natural feeder bluff.  Because the CCDL is set back from the shoreline, Anchor’s approach to stabilization included an earth fill, rather than a major excavation.  In support of this design, Anchor QEA performed several slope stability analyses to determine the feasibility of various slope and material configurations.  The final design consists of the construction of a rock buttress supported by a subsurface shear-key wall, a multi-component engineered cap, and drainage controls to manage infiltrating stormwater within the vicinity of the waste mass.  Anchor QEA provided construction inspection and management support during the multi-year construction project.  Our services included submittal review, construction engineering, change order evaluation, and environmental monitoring.

For more information on this project, please contact Rebecca Desrosiers at rdesrosiers@anchorqea.com.