FP McCann Precast Concrete Segmental Shafts Installed as Part of Award Winning Canadian Sewer Infrastructure Project

Project: Malcolm Tweddle & Edith Rogers (MTER) Sewer Improvement Initiative, City of Edmonton, Alberta, Canada

Client: EPCOR Utilities

Main Contractor: AECOM

Lift Shaft & Stair Flight Install: Bothar Inc.

Products Supplied: Precast Concrete Segmental Shafts; 11.4m id; 6.0m id; 3.66m id

FP McCann’s precast concrete segmental shafts have played a fundamental role in a ‘trenchless technology’ award winning infrastructure project in Edmonton, Canada.

The 2023 “Trenchless Technology Project of the Year New Installation Winner” was presented to the Malcolm Tweddle & Edith Rogers (MTEPCOR working in conjunction with consultant engineer AECOM. The US$22 million microtunneling and associated storm sewer infrastructure work was awarded to trenchless construction specialist Bothar Inc. Along the line of the storm sewer pipes, the Bothar team proposed that launch and reception shafts for the TBM’s become permanent manhole structures on completion of works. On considering ground conditions, working area restrictions and the harsh winter weather, it was determined that circular precast concrete segmental shafts sunk using the jacked caisson method were the best means of construction, reducing the footprint required for excavation.

Recognising FP McCann as a market leader in the manufacture of precast concrete segmental rings, Bothar placed an order with the Company to supply seven segmental shafts. Two 11.4m id, three 6.0m id and two 3.66m id caisson shafts were sunk to varying depths between 8 metres and 15 metres. Both of the 11.4m id shafts were constructed to launch the Herrenknecht 3.685m OD MTBM; two of the three 6.0m id shafts were reception points for the MTBM, with one used to launch the Herrenknecht AVN800 pipe jacking machine. One of the 3.66m id segmental shafts was sunk to retrieve the AVN800 boring machine, the other to complete a lateral T-connection to the 3000mm id tunnel.

Once the microtunneling work was completed, all seven of FP McCann’s precast segmental shafts were utilized to support precast concrete roof structures that in-turn supported the standard manhole risers, designed to carry the permanent traffic loads. This approach negated the need to construct new manholes to full depth and backfill inside the already constructed shafts.

Commenting on FP McCann’s precast concrete segmental rings Liam Ó Cuanacháin project manager for Bothar Inc. says, “Utilising FP McCann’s precast concrete segments brought several advantages. Working with small site footprints and in residential areas, this construction methodology was the least intrusive. The major benefit FP McCann’s segmental rings brought along with ease of construction, was the ability to use the watertight segments as the permanent drainage structures. They are the finished product – Using them negated the need to construct a manhole inside the shaft and to backfill thereby improving the project schedule”. Liam adds, “The circular segmental caisson shafts were significantly safer to install vs. conventional shafts and the reduced footprint required for excavation, was particularly beneficial on this project as there were significant traffic restrictions at each shaft location”.

The award winning MTER storm sewer project serves as an inspiring example for the multi-national microtunneling and shaft sinking industry and showcases how infrastructure development can be seamlessly integrated into established urban settings for the greater benefit of those communities.