Nucor Skyline’s HZ-M king pile wall a cost-effective solution at Port of Trois-Rivières

By Janet M. Himstead, Nucor Skyline

The Port of Trois-Rivières is a large multi-modal facility that combines sea, rail, and road. The port serves both domestic and international markets from its location on the north bank of the St. Lawrence River, where it meets the St. Maurice River, about halfway between Québec City and Montréal. 

The port handles approximately 55,000 trucks, 11,000 freight cars, and 240 ships per year, which makes it one of the largest ports in Québec and Eastern Canada. A wide range of products flows through the port including general cargo, dry, and liquid bulks. 

In 1824, Mathew Bell, owner of the Forges du Saint-Maurice, built the first dock and warehouse, establishing the Port of Trois-Rivières. Shortly thereafter, John Molson, a powerful ship owner of the day, followed suit and built three more docks in 1825 and acquired several more in 1840. As these were private facilities, the municipal administration determined that a public dock was needed for the ferries connecting the city to the Village of Sainte-Angele de Laval, on the south shore of the St. Lawrence River. It was 1858, and this was the first public initiative for the port. Throughout the years, the port has gone through many changes and has been overseen by several different agencies, including the Council of National Ports, a federal agency that manages many of the other large Canadian ports. 

In 1999, the Trois-Rivières Port Authority (TRPA), took over management of the port. Recently, the TRPA has undertaken a large project to overhaul some of the outdated wharfs and facilities at the port. The extension of Pier 10 at the port is one of the major construction projects. This extension will replace the aging and obsolete Pier 9, which was built in the 1930s. The extension of Pier 10, with a berthing length of 133 metres, will increase the outdoor storage space at the pier from 3,000 square metres to 12,000 square metres.

The Port of Trois-Rivières is an important economic development tool for several regions of Québec and supports many regional companies in the shipping of their products and in supplying raw materials. The improvements made during this rehabilitation project will enable the port to better support the development of the regions it serves.

In order to accelerate the process, the port decided to tender the project seeking design- build solutions. The multimillion-dollar contract was awarded to Hamel Construction of Québec City. Hamel Construction was established in 1970 and has grown and diversified over the years by forming different partnerships for complex and large-scale projects.

Hamel Construction worked with Nucor Skyline to design the right solution for the pier. Due to soft soils on the bottom of the St. Lawrence River, the engineering department at Nucor Skyline suggested a king pile wall that would be anchored with tie rods to a buried sheet pile wall. The HZ-M king pile wall was the most cost-effective system for this pier extension. The design allowed wa- ter depths of 12 meters and a final retained height of 17 metres from the top of the wall to the riverbed.

Marine applications often utilize combined wall systems, consisting of king piles and pairs of intermediary piles, where they provide increased capacity compared to regular sheet pile walls. The Nucor Skyline HZ-M system is fully interlocking and is composed of heavy king H piles with sheet pile connectors attached to the flanges to permit the threading of intermediary sheet piles. The intermediary sheet piles transfer the soil and water pressures to the king piles, which carry most of the load. The king piles are the primary element in combined wall systems and are usually 25 per cent to 60 per cent longer than the intermediary piles. This allows for increased axial capacity of the system.

In order to optimize the final design solution, Nucor Skyline suggested using a higher grade, S430GP steel (430 MPa), for this project. Nucor Skyline also provided cold formed sheet piling for the anchor wall and a tie-rod system composed of threaded bars with couplers to facilitate installed lengths of 35 metres. Each of the 80 king piles were tied above water level with an articulated system. The bars were spaced at 1.9 metres and connected directly to the king piles. With one tie rod per beam there was no need for a waler system on the main wall, only the anchor wall. 

Construction began in early June of 2017, with the contractor preparing the site by demolishing the aging Pier 9 and excavating as needed. The installation of the stone embankment along the river immediately followed the demolition and excavation at the site. In mid-July 2017, driving began for the combined wall system, with 11- to 15-metric-ton king piles driven 18 metres deep by a vibratory hammer. The king piles ranged in length from 28.65 to 33 metres. The intermediary sheet piles, ranging from 18 to 22 metres, were then driven eight meters through the soft soils of the riverbed. Ocean vessel delivery ensured the supply of long lengths in one piece directly to the Port of Trois-Rivières. The improvements from this rehabilitation project will enable the port to better support the development of the regions it serves. 

The new wharf section is now in full operation and provides year-round service via the seaway. 

For more information, please visit: www.nucorskyline.com.