Award of Excellence: Bayview Avenue Extension

CATEGORY: TRANSPORTATION

McCORMICK RANKIN CORPORATION/ECOPLANS

Bayview Avenue in the Regional Municipality of York north of Toronto passes through the environmentally sensitive Oak Ridges Moraine. It is a two-lane rural roadway designed to support the Region’s growth while being sensitive to the area’s topography and natural environment.

McCormick Rankin Corporation and its subsidiary, Ecoplans, were retained to plan and design the Bayview Avenue Extension between Stouffville Road and Bloomington Road in Richmond Hill. Given its high environmental and public profile, the project went through both the class environmental assessment and individual environmental assessment study processes.

Two particularly innovative approaches that were developed for the project were:

a pilot and research project to create a wetland habitat;

a study of salamander migration (focusing on the rare Jefferson Salamander), and the design of different dedicated amphibian crossings along the roadway.

These approaches were instrumental in securing agency approvals for the project, and they advance the science of habitat creation and wildlife crossing design.

While effort was made to preserve wetlands, it was not possible for the road to avoid four small wetland pockets and the edge of Forester Marsh. In recognition of this situation, the proponents undertook to create a new wetland habitat on the Lake St. George Field Centre property, which is owned and operated by the Toronto and Region Conservation Authority. The wetland was designed in consultation with staff from the conservation authority and gives them opportunities for research and for educating visitors to their field centre.

In a strategically selected open area, three new wetland “cells” were excavated, each with differing levels of management effort:

(1) a “Do Nothing” cell that was excavated but received no subsequent treatment (such as plantings or seedbank material);

(2) a planted wetland cell that was excavated and then planted with nursery herbaceous stock, as well as upland tree and shrub plantings;

(3) an excavated wetland cell that was lined with wetland substrates salvaged from the wetland zones removed by the road.

The different cells provide an outdoor laboratory where the pattern of resulting wetland development and wildlife use can be tracked over time. The site provides habitat for reptiles and amphibians that is well removed from Bayview Avenue and functions as a north-south linkage between Forester Marsh and Lake St. George. It has a sculpted edge and a variety of depths and substrate conditions that encourage biological diversity.

The project also identified and protected archaeological sites, and a visitor trail was integrated into the design.

Salamander crossings

Jefferson Complex Salamanders had been observed on Stouffville Road near the area of the road. This salamander group emerges from overwintering sites and migrates during rainy or very humid nights to breeding ponds in the spring. The pure Jefferson species is very rare in Ontario (Rank S2) and was recently designated as “threatened” in Canada.

Extensive field sampling in Spring 2002 confirmed the presence and movement of the Jefferson Salamander as well as several other amphibian species. The study involved 238 pitfall traps and 2.2 km of drift fencing.

A literature review and discussion with other experts identified the following key considerations in the provision of amphibian tunnel crossings:

providing adequate light, moisture, temperature and substrates;

avoiding tunnel flooding or high velocity water flows through the tunnel; and,

providing suitable funnel fencing to direct migrating animals to the tunnel without extensive out-of-way travel.

Five amphibian tunnels were installed by the fall of 2002 with design elements that reflected the above guidelines. Since research into salamander tunnel requirements is still evolving, the project uses different designs and a monitoring program is determining how they are used. The tunnels were constructed of different materials, and in sizes up to 30 metres long and 1.7 metres in width. Key features included countersunk designs using native substrate soils, and flat gradients to maintain the wetting and dampness of the substrates. Shafts and grates provide light and allow rainfall to enter, and the entrances are designed to funnel the amphibians into the crossings.

The Bayview Extension project included other environmental aspects such as a unique woodland edge management plan to mitigate the impacts of the roadway on the Jefferson Forrest. An underpass structure was also constructed to enable larger wildlife to cross the road corridor.

The project costs, including roadworks, wetlands, engineering and environmental approvals, totalled $12.6 million.

Name of project: Bayview Avenue Extension, Richmond Hill, Ontario

Other key players: Archaeological Services (archaeological assessment), Golder Associates (geotechnical)