Construction of a Multi-Use Pathway on Soft Compressible Deposits– Case Study

ABSTRACT: As part of a road upgrade of Victoria Street in the Town of Whitby, in the Regional Municipality of Durham, Ontario, a Multi-Use Pathway (MUP) was constructed in 2018. A section of the MUP about 150 m in length with embankments up to 3.5 m high, traversed the marshy flood plain of the Lynde Creek, which comprised of peats/organic soils up to about 6 m thick with moisture contents in the upper 3.6 m as high as 260%. This MUP alignment included a buried gas main towards the southern end of the proposed cross-section. In view of the shallow gas main (at the shallowest point, the invert of the gas main (0.3 m dia.) was about 1.8 m below ground surface), intrusive ground improvement methods were not favoured. A light-weight fill approach was adopted using “Cematrix” cellular concrete for the lower portion of the embankment and granular fill was used above to suppress buoyancy. Field shear vane testing and CPTU testing which shed light on the shear strength and consolidation characteristics of the compressible deposits coupled with FEM modelling enabled construction to proceed in a two-stage approach. The various geotechnical challenges of this project are discussed in the paper.