Monumental SienaStone Wall for GO Transit
Fully Monitored Wall Exceeds Expectations for MTO Demonstration Project
Developer: Go –A Division of Metrolinx
Civil Engineer: SRM Associates
Wall Designer: Risi Stone Inc.
Wall Supplier: Unilock Ltd
Wall Installer: Regent Landscape Ltd
Site Inspection/Certification: Terraprobe Inc. T
Surveyor: Schaeffer Dzaldov Bennett Ltd.
In the spring of 2009, GO Transit, the public transit service for the Greater Toronto and Hamilton areas, planned an ambitious parking expansion project at the existing Maple GO Station in Vaughan, Ontario.
In order push the site to the limits and maximize usable parking, a large 6m high, 300m long retaining wall was specified by the Civil Engineer. Based on numerous, past successful past projects with GO Transit, Risi Stone Systems provided a full Design for the project using the SienaStone System.
The Wall Contract was won by Regent Landscape, one the GTA’s premiere Wall Builders.
Due to scheduling, the SienaStone wall was constructed in two phases, with the first 100m commencing in the summer of 2009. During this phase, poor site conditions required additional foundation replacement and improvement using geotextiles to achieve the required bearing capacities stated in the Design.
The remaining 200m long section of Wall was built in February 2011. Around the same time, Risi Stone Systems and Unilock had undertaken to advance the SienaStone product on the Ministry of Transportation (MTO) Designed Source for Materials (DSM) List from the existing status as a “Gravity” or “Non-Reinforced” wall to a Geogrid Reinforced System. As part of the approval process, the MTO requires a demonstration project to be regularly monitored following construction for a period of 1 year to observe settlements or movements that may occur. The size and scale of the GO Transit project was a good fit for the type of structure the MTO would consider, so detailed monitoring began shortly after construction. The year round survey was conducted once every two months for 6 survey points at the request of MTO.
After year round survey monitoring, and despite being constructed in the middle of winter, the SienaStone wall performed beyond expectations, with little to no movement observed. The maximum movement on the 6m height was in the range of 3mm-4mm, which is considered to be within measuring tolerance by the Surveyor.
This level of performance is a testament to the Contractor’s thorough quality control and construction practices, which are as important as any aspect of the design or engineering, the Risi Stone design process, as well as the stability and dependability of the SienaStone wall system.