Product Supply Tunnel Refurbishment, Imperial Oil, Sarnia - 2010 - ongoing

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At Imperial Oil’s refinery, an aging combined steel liner plate and extended CSP tunnel under a city arterial roadway was corroding to the point that its structural integrity was a concern. Rebuilding the tunnel and rerouting the 45 pipes carrying various products and steam would have been a major undertaking that wasn’t in Imperial Oil’s plans.

The decision was made to try to install a structural lining without disturbing the pipes. This was complicated by there being very little clearance between some of the pipes and the corroding liner and the tunnel liner plate and CSP being different diameters. A laser scan of the tunnel interior was carried out to determine whether any liner could be physically installed. It was determined that two different sized tunnel liner plate segments could be installed around the pipes.

This was not easy work trying to fit and bolt the steel segments together in behind the pipes. It

was very hot in the tunnel and the safety gear required for the confined space safety protocol

was also an impediment. After the arduous installation of the interior liner, the annular space was grouted to lock the structures together. The worst 2 sections of the tunnel were lined in 2010 with several more sections planned in the near future.

The most historic building in Canada, located adjacent to Centre Block, was founded at ground level and not connected to Parliament Hill services. As part of a complete renovation it was decided to construct a basement under the building for additional archive storage and

mechanical equipment.

This involved removing 5,000 m³ of limestone from beneath the building all the while supporting it. A shaft had to be sunk directly behind Centre Block from which a tunnel was dug under the Library. 

If that wasn’t enough of a challenge, the rock removal had to be completed with minimal vibration which precluded the normal blasting. Every low-vibration rock removal technique that existed was tried before a solution was found that led to the successful completion of the project.

Access for passengers to the increasingly busy Toronto Island Airport was by ferry across the 200 m wide Western Gap of Toronto Harbour. The challenge was to construct the largest diameter tunnel ever attempted in Toronto shale with minimal rock cover under the channel bottom. 

This was further complicated by undisclosed channel blasting done by the St. Lawrence

Seaway in the 1950’s and piling installed during an aborted 1930’s tunnel attempt that damaged the rock.Large shafts were constructed on both the mainland and the Island using secant piles to support the wet sand overburden. The secant piles were anchored into the shale.

Working areas were extremely small to accommodate airport operations on both sides of the channel. The design-build solution was to mine 7 interlocking 2 m diameter tunnels across the channel and fill them with concrete to form an arch. The main tunnel excavation was then carried out under the supporting arch with breakthrough to Toronto Island being achieved in August 2013. A concrete lining was poured to complete the civil work.

The rapidly developing area of Seaton in north Pickering required a fast-track sanitary trunk

sewer to service the housing development that were already under construction. 

This required a 24 hour a day, 6 days a week (sometimes 7) operation to try to meet the schedule. It also required the sinking of 10 deep shafts using pre-cast segments, shotcrete, steel liner plate and poured in place liners. 

The project was completed just as the home sales were closing in spite of very difficult hard till soils with large boulders that took its toll on the excavation equipment.