Powering Manitoba with MMTP

Tower assembly using sky crane (guyed).

Completed last year, the Manitoba–Minnesota Transmission Project is bringing electrical security and more access to U.S. markets

By Paul Adair

Going into service on June 1, 2020, Manitoba Hydro’s new Manitoba–Minnesota Transmission Project (MMTP) is a 213-kilometre, 500 kilovolt AC transmission line designed to deliver additional electricity down to the public utility’s southern neighbour, Minnesota Power, over the next 15 years. The completion of MMTP creates a new level of interconnectivity that will strengthen the overall reliability and grid stability of Manitoba’s electricity supply, allowing Manitoba Hydro to fulfill current export sales agreements and providing additional access to markets in the United States, as well as further import capacity if required during emergency situations.

Manitoba Hydro segmented the construction of MMTP into two contracted sections, with Valard Construction working on Section Two from September 2019 to April 2020. This stretch of the project included 132 kilometres of transmission line installation, and incorporated such activities as access, clearing, tower assembly, tower erection, distribution crossings, the stringing of triple bundle conductor and including optical ground wire (OPGW).

“Valard is Canada’s largest premier utility contractor and has the capacity and capability − together with local knowledge and experience − to successfully construct,” says Dave Torgerson, Chief Operating Officer at Valard Construction. “The

project was completed on time within a compressed schedule of seven-and-a-half months.”

Valard used a variety of different piling equipment, large excavators, and cranes for the project’s precast foundation solutions. The screw piles were installed using a 470 John Deere excavator and 880D Tigercat with 225,000 ft./lbs drive-heads.

While the concrete foundations were supplied by Manitoba Hydro, Valard produced all material for the screw piles and driven piles in-house, which were a mixture of lengths and helices.

In the sections of the project where seepage and sloughing in the excavations were extensive, or in places with several metres of spongy peat rather than firm soil, the pre-cast concrete foundation proved to be extremely difficult to install, and precast concrete foundations were considered not feasible. In the face of this challenge, Valard proposed an alternative driven-pile solution that was successfully used following testing by Manitoba Hydro.

“Our driven-pile solution was something that Manitoba Hydro had never used before but has been extensively used by Valard,” says Torgerson. “The driven piles were valuable for installing in those areas where other solutions were just not possible because of difficult and unknown subsurface ground conditions.”

Valard’s driven-pile solution consisted of driving the 18- to 24-metre deep pipe piles through the upper wet weak layers and terminating in the lower denser soils, assuring a sound foundation for the towers and resulting in a much faster and economical installation, particularly when compared to the installation of the precast concrete footings, helical piles, or micropiles.

Representative samples of the driven piles were tested using Pile Dynamic Analysis (PDA) and the sample capacities were determined using Case Pile Wave Analysis Program (CAPWAP) software. This PDA testing proved invaluable by confirming the pile’s capacity and reducing the amount of extensions and splicing required.

“Foundations are generally the longest activity in the construction of a power line, and if you can shorten this, you have a good chance to meet − and perhaps beat − the schedule,” says Torgerson. “The driven−pile solution offered this for MMTP, with savings. Manitoba Hydro was very engaged and receptive to the driven−pile solution, allowing Valard to perform trial tests, driving, and Pile Dynamic Analysis (PDA) in various ground conditions to determine the optimal pile and driver design.”

The long path of the MMTP crosses the Red River Floodway south of Winnipeg, which presented an engineering challenge for Manitoba Hydro’s in-house designers to overcome while following the stringent requirements for placing towers on either side of it. The design of these foundations resulted in one of the largest cast-in-place foundations ever used on a transmission line project in Manitoba, taking approximately three months to install.

“When the floodway is in use, the MMTP tower footprints could potentially be submerged,” says Project Engineer Eryn Brown. “As a result, in collaboration with the provincial floodway authority, Manitoba Hydro designed foundations that would be elevated to clear a once-in-200year flood level.”

Provincially, the MMTP is a Class 3 development under the Manitoba Environment Act, which required a comprehensive scoping process and Environmental Impact Statement (EIS). A Clean Environment Commission Hearing was also held and recommendations from that body informed the Environment Act Licence that was ultimately issued at the Provincial level.

And because the project is an international power line impacting an existing in-

Foundation at the Red River Crossing.

ternational power line (Riel IPL), a Federal Certificate was also required to move the project forward. This required a comprehensive federal application and a public hearing with the Canada Energy Regulator (previously known as the National Energy Board, or NEB). The project needed to meet requirements of both the NEB Act (now the CER Act) and the Canadian Environmental Assessment Act.

All told, the regulatory review process for the project took roughly four years to complete: the Environmental Impact Statement (EIS) for the project was filed with the Province of Manitoba on September 2015, and the licence was received April 2019; the application with the NEB was filed December 2016 with the certificate received by August 2019.

“There were numerous steps taken to

MPM25 Junttan pile driver installing a pile for the only driven-pile anchor on the MMTP line.

ensure the project had the least impact to the environment,” says Brown. “Manitoba Hydro used an iterative, transparent and streamlined routing methodology, informed by expert analysis and comprehensive engagement with Indigenous and local communities to plan a route that balanced and limited impact. This included input from Indigenous traditional knowledge studies and environmental field studies.”

A comprehensive environmental protection program was also designed to limit impacts of the project on the environment, as well as on Manitobans. As part of this program, Manitoba Hydro produced a wide variety of plans to guide contractors during construction, such as (but not limited to) a biosecurity management plan, cultural and heritage resources protection plan, golden winged-warbler habitat management plan, and rehabilitation and invasive species management plan.

In addition, Manitoba Hydro established a MMTP Monitoring Committee comprised of representatives from Indigenous communities, Manitoba Hydro, and the Province. The purpose of this Committee was to support effective and meaningful Indigenous participation in monitoring the construction and operation of the MMTP project.

“The MMTP Monitoring Committee hired four Indigenous monitors (two compliance and environment monitors, a traditional monitor, and a communications monitor), who reported to the MMTP Committee members on project activities,” says Brown. “These monitors would work alongside Manitoba Hydro crews to monitor the implementation of mitigation measures and help ensure protection of the culturally and environmentally sensitive features.”

Manitoba Hydro also established the MMTP Landowner Advisory Committee, a group of landowners affected by the project who met regularly to review their concerns and discuss how Manitoba Hydro has resolved them, as well as advising on ways to effectively mitigate any issues.

The shortened schedule of the MMPT (from an expected two to three years down to just eight months) proved to be

a significant challenge given the terrain along the right of way. This challenge was further compounded by unseasonal fall flooding in 2019 that caused a six to eight week delay and a provincial state of emergency called for the surrounding areas.

“While the aggressive schedule was our biggest challenge, another difficulty was related to access, with plenty of low lying land, high water tables, and deep weak soils overlain by muskeg that was exacerbated by the extreme rainfall and flooding last fall,” says Torgerson. “Valard was able to overcome all of these challenges − and more − through quick project planning Interpipe Inc. is a steel pipe distributor of new and used structural steel pipe. We have two and our expertise in the industry.” For a project like this, Valard would have preferred to wait until freeze-up ONTARIO 3320 Miles Road, RR#3 Mount Hope, Ontario large stocking locations of Seamless, ERW, to get access from winter trails, snow L0R 1WO Interpipe Inc. is a steel pipe distributor of new and used structural steel pipe. We have two large stocking locations of Seamless, ERW, Spiralweld and DSAW pipe. Spiralweld and DSAW pipe. 3” OD – 48” OD in a variety of wall thicknesses are stocked in both locations. Interpipe Inc. is a steel pipe distributor of new and used structural steel pipe. We have several stocking locations of Seamless, ERW, Spiralweld and DSAW pipe. ramps, and ice bridges. But because of the tight schedule and the extremely wet fall weather, timber matting needed to be laid down over certain areas along the project’s right of way to provide access. Once ONTARIO 3320 Miles Road, RR#3 Mount Hope, Ontario L0R 1WO Local: (905) 679-6999 Local: (905) 679-6999 Toll Free: (877) 468-7473 Fax: (905) 679-6544 ONTARIO 3320 Miles Road, RR#3 Mount Hope, Ontario L0R 1WO Local: (905) 679-6999 3” OD – 48” OD in a variety of wall thicknesses are stocked in both locations. Piling Pipe 80,000 min yield seamless pipe for Micro Piling. Piling Pipe 80,000 min yield seamless pipe for Micro Piling. Seamless and ERW pipe for Driven Piles, 3" OD – 48" OD in a variety of wall thicknesses are stocked in all three locations. Piling Pipe 80,000 min yield seamless pipe for Micro Piling. the ground froze in early November, however, it allowed contractors access to most areas of the project site under typical frozen conditions. The tower installation was also able to be expedited by flying the towToll Free: (877) 468-7473 Fax: (905) 679-6544 QUEBEC 805 1 ère Avenue Ville Ste. Catherine, Quebec QUEBEC 805 1 ère Avenue Ville Ste. Catherine, Quebec J5C 1C5 Toll Free: (877) 468-7473 Fax: (905) 679-6544 QUEBEC 805 1 ère Avenue Ville Ste. Catherine, Quebec Seamless and ERW pipe for Driven Piles, Screw Piles and Drill Piles. Large Diameter pipe for Driven Pile or Caissons. Screw Piles and Drill Piles. Large Diameter pipe for Driven Pile or Caissons. Seamless and ERW pipe for Driven Piles, Screw Piles and Drill Piles. Large Diameter pipe for Driven Piles or Caissons. ers in with air cranes and using helicopter erection methods to set the towers. Other challenges faced by the MMPT J5C 1C5 Local: (450) 638-3320 Toll Free: (888) 514-0040 Fax: (450) 638-3340 Local: (450) 638-3320 Toll Free: (888) 514-0040 Fax: (450) 638-3340 J5C 1C5 Local: (450) 638-3320 Toll Free: (888) 514-0040 Fax: (450) 638-3340 were primarily related to the amount of pre-work required on preparatory materials and the almost four-year regulatory process, as well as the great efforts that went into stakeholder engagement and concerns regarding ground conditions. And as geotechnical drilling often proved unexpected subsurface conditions ongoing throughout project, Valard would also encounter artisan water conditions in certain areas that would further complicate the installation process.

“All of this, as well as a pandemic at the end, and to still come in on schedule and on budget — that’s a testament to the amazing abilities of the team and the staff who worked on MMTP from all phases of the project,” says Brown. l www.interpipe.com