A recent area of maintenance in the Greater Toronto Area included the reinforcement and rehabilitation of numerous drainage culverts that extend across a highway
Planning for a new highway to bypass urban congestion in the Greater Toronto Area (GTA) began in the 1950s. In 1997, the central portion of the highway from Hwy 403 In Mississauga to Markham Road in Markham was opened. Areas have since been widened with additional lanes to meet the growing needs of motorists. Extensions eastward and westward now serve more outlying communities. The concessionaire for the highway, 407 ETR Concession Co. Ltd., boasted the world’s first all-electronic, open-access toll highway that now spans 108 kilometers (67 miles).
As the concessionaire for the highway, 407 ETR is responsible not only for the customer service and police enforcement along the highway but also for all maintenance and construction. One recent area of maintenance included reinforcement and rehabilitation of the numerous drainage culverts that extend across the highway. The existing culvert system utilized corrugated metal piping (CMP) and in time, had experienced degradation. The CMP included areas of over-deflection, corrosion and sediment buildup. The 407 ETR has planned multi-year contracts to reinforce/rehab the existing culverts using different technologies based on the diameter of the culverts.
The performance requirements outlined in their repair specifications contained structural, corrosion and hydraulic considerations. For large diameter culverts (approximately 1,800 millimeter and larger), rehab via sliplining using FRP systems was specified. Alliance Verdi Civil Inc. won a recent contract and offered, under value engineering, the use of Centrifugally Cast Fiberglass Reinforced Polymer Mortar CCFRPM Pipe. The contract included rehab of approximately 773 meters of culvert ranging in size from 1,800 millimeter -2,400 millimeter. Hobas Pipe USA supplied 268 meters of 1,600 millimeter and 505 meter of 2,159 millimeter pipe for sites located along the 407 stretching from Oshawa southwest to Burlington.
Before any work could begin, sediment needed to be removed and sections of the corrugated metal pipe had to be replaced in locations that exhibited excessive deformations. Then to maintain the required slope, slurry was placed at the invert to elevate some depressions in the existing metal pipe. The liner pipe was easily installed due to the lightweight nature of the CCFRPM Pipe. A Volvo ECR305 excavator pushed the pipe from one end of the culvert across the entire run. A 350 millimeter-long fiberglass pushing ring manufactured by Hobas was used to transfer load from the excavator bucket to the push ring and then the pipe. The longest push to date has been 96 meter. Once each culvert was sliplined, the annular space was grouted.
The high stiffness design of the Hobas liner pipe was able to meet the structural requirements and allowed for easier installation and grouting. The project specification specified that the flow capacity must not be less than 90% of the existing culverts’s flow capacity.
Benefits of this Hobas fiberglass liner:
- Flow is maintained without any decrease due to the lower manning’s coefficient compared to the existing CMP;
- The non-reinforced 40 millimeter polyester surface provides superior abrasion resistance over other piping options, and
- Hobas Pipe can meet the specified requirement of a minimum 75-year design life.
Hobas has been widely used for sanitary sewer pipes, but, more recently, the product has been utilized for storm water projects due to the installation advantages.
“This was the first time using Hobas pipe, and in fact, the first project sliplining. Overall it was a smooth process,” stated Pat Dileo, project manager for Alliance Verdi Civil, Inc. of Bolton, Ontario.