Meadow Avenue Remediation: A New Direction in Contaminated Site Management

For 50 years the Meadow Ave site, a 200 metre foreshore area in south Burnaby near the Fraser River ’s Big Bend , was the site of a wood preservative operation that produced pressure treated railway ties and utility poles. In the summer of 2000, the site became a remediation project in search of a solution.

The preservation plant closed in the early 1980s and the site underwent remediation measures. However, contaminants were again discovered to be migrating into the Fraser River , and the ensuing litigation and court decisions comprise some of the most significant contaminated sites case law in BC. In 1997, a Remediation Order was issued from the provincial environment ministry, and by the summer of 2000, the Order was amended by the Ministry to include a prescriptive remedy with a seemingly unachievable schedule of deadlines.

Following on the heels of the previous consultants, Keystone was retained to undertake the prescribed remediation plan and to restore confidence by meeting the first Ministry deadline. Not prepared to support the projected $60 - $70 million remediation cost, Keystone saw the opportunity to devise a unique engineering solution that met strict environmental objectives, improved natural habitat and riverfront aesthetics, and preserved the economic vitality of this industrialized segment of the Fraser River, at ½ the projected costs. The innovative solutions proposed were to be combined to form a single unique solution. But there were many complexities because the affected properties were not owned and controlled by the proponents, but by a number of private and public Stakeholders. Exacerbating the issue was that the foreshore was the property of the Crown, and leased to operating tenants by the North Fraser Port Authority, the lead agency for the Fraser River Estuary Management Program (FREMP). At least a dozen permits and approvals, obtained through all levels of government, would be required to complete the project. And those permits would have to be complete to implement the solution economically.

Building on the initial concept, fourteen remediation options were developed for consideration, all with varying design features intended to bring balance between the many project objectives. Using computer simulations to model the environmental performance of various wharf configurations and their components, the design evolved from a simple wharf to an integrated, eco-efficient system.

Cap System
Dredging and land filling the contaminants presented the highest risk of contaminant release and would amount to the lion’s share of costs. We avoided this with a capping system designed to eliminate the need to dispose of 30,000 tonnes of contaminated sediments. When initially proposed, the DFO employee, now with a competing firm, told Keystone “We will not allow a cap over contamination. You must dredge all accessible contaminants out and dispose of them. You will restore the foreshore site to original condition or better.”

Regardless of DFO's initial sentiment, Keystone pursued the scientific option with rigor and diligence. We finally did receive DFO approval for this novel approach, which led to a savings of approximately $35 million. Subsequently, others in DFO were active and constructive participants in the approvals process, and brought their colleagues to the site to observe the outstanding job of remediation in progress.

Groundwater Cut-off Walls
A system of sheet pile cut-off walls, optimized for passive groundwater control, was developed to isolate contaminated sediments and control groundwater, redirecting and attenuating the flow of contaminants into the foreshore area.

Marsh and Riparian Habitat
Habitat compensation was integrated into the cap system and cut-off walls. The combination of wildlife-attracting habitat and working river features compliments and enhances the educational potential of the nearby municipal public pathways and river viewing areas. The cap provided a foundation for a constructed inter-tidal marshland and the shoreline extension was developed into riparian habitat.

Caisson Dredging
The extent of peripheral dredging was limited through ecological risk assessment. Residual shallow sediments were removed using an innovative technique developed by the contractor in concert with our engineering team. This method allowed dredging to be performed “in-the-dry”, in virtual isolation from the tidally-influenced river, eliminating the need for silt curtains and dredge-water treatment, required with traditional dredging methods.

Further Cost Reductions
The engineering team went on to design in-river controls Keystone developed a “Tiered” program for monitoring of construction; the success of these initiatives satisfied DFO who allowed the final stages of the project to progress through the traditionally restricted fisheries-sensitive period. This also substantially reduced the construction schedule and project costs.

While the project began as a response to a provincial government directive, the Meadow Avenue remediation project evolved into a unique eco-efficient, integrated solution which addresses contaminated sediments and is expected to become a model approach for undertaking similarly complex projects in the future.

The Association of Professional Engineers and Geoscientists awarded this project their 2004 Environment Award for outstanding achievement in environmental engineering - Design, Construction and Monitoring. The Consulting Engineers of BC presented an Award of Merit for Engineering Excellence. At a recent speaking engagement (October/05), a technical manager from the Ministry of Environment praised the project as an innovative example of consultants outperforming prescriptive remedies, and declared that it represented “the most Bang for the Buck” of any contaminated sites project in BC.

Please contact Don Bryant, Principal at Keystone Environmental for more information on this project, 604-430-0671