February 2020, Vol. 247, No. 2
Features
FortisBC Lower Mainland Intermediate Pressure System Upgrade Project
By Gary Ziehr, Vice President, Oil and Gas Projects, Michels Canada
Michels Canada is working with gas distribution company FortisBC to complete a two-year project to upgrade 12.4 miles (20 km) of the Lower Mainland Intermediate Pressure System Upgrade (LMIPSU), which serves more than 210,000 customers in Vancouver, Burnaby and Coquitlam. Already one of the most densely populated areas in Canada, metropolitan Vancouver’s population is nearing 2.5 million people and continues to rise.
Commercial and residential growth is happening at a steady rate and is projected to continue through diverse investments, which increases the demand for the safe and reliable delivery of natural gas.
Michels Canada is a utility and transportation contractor with extensive pipeline construction experience throughout Canada. Leveraging this knowledge and experience, Michels developed and executed a plan specifically designed for this high-profile project.
Michels is installing a 30-inch (762-mm) gas line beneath the city streets to replace the aged 20-inch (508-mm) steel line built 60 years ago. Construction started in spring 2018 in Vancouver and wrapped up before the holiday season in Burnaby with about 5 miles (8 km) completed. This year, crews finished the remaining 3.7 miles (6 km) in Burnaby and 3.7 miles in Coquitlam in early December.
Constructing a large linear project like LMIPSU within an urban landscape presents many challenges not typically seen on similar projects. With a combination of experienced leadership and a commitment to safety, quality and the environment, Michels is succeeding on an extremely complex and challenging project.
Safety Culture
On an urban project, maintaining public safety and minimizing disruptions is of paramount importance to the customer, the surrounding affected communities and the contractor.
The approach to health, safety and environmental (HSE) initiatives developed by Michels HSE department are comprehensive and holistic. Between April 2018 and September 2019, Michels completed nearly 1 million hours of work on LMIPSU and had no lost-time injuries and only one recordable injury. While working within this densely populated urban environment, the project has experienced only a few minor vehicular incidents while traveling close to 1.1 million miles (1.8 million km).
A significant factor in Michels’ success on the project has been the relationship between Michels and its subcontractor partners. The scope of the work required the services of third-party contractors to complete the functions of:
- Asphalt milling, hauling and disposal of excavated trench spoil
- Importing aggregate material
- Resurfacing and line painting
- Traffic control/flagging services
- Utility relocations
The project team initially invested a substantial amount of time prequalifying subcontractors, which allowed the team to determine which subcontractors present the best option for each activity targeted for the project to succeed.
Once selected, each subcontractor met face to face with members of the Michels project leadership team to outline, discuss and agree on roles, expectations and how Michels and the subcontractor would work together to adhere to the project’s safety requirements.
Once the subcontractor was actively engaged in work on the project, Michels project leadership team continually monitored the performance of each subcontractor and provided support by way of regular individual subcontractor meetings, joint worksite inspections and a monthly joint subcontractor alignment meeting hosted at the Michels project construction trailers.
Furthermore, to reinforce the safety culture, Michels launched the Mi-VIP and Me campaign in 2018 to encourage all employees to make a personal commitment to safety. On July 19, 2018, the project team ceased all field work for the afternoon and invited family, friends, Michels Corporation executives from Brownsville, Wisc. and owner partners to a Mi-VIP and Me Safety Celebration. The event, attended by more than 500 people, was a huge success that workers talked about for weeks.
Planning
Comprehensive planning is an essential part of any major construction project. For an urban pipeline construction project, there is special consideration to ensure permitting, scheduling, logistics and equipment allocations align to allow successful integration of each task and function of the work.
Permits are classified into two major categories: municipal and third-party utilities. Municipal permits include all pre- and post-project requirements associated with permission to work within the city and on the roadways while adhering to lane closure conditions and noise variances.
Third-party utility permits include obtaining approvals from many other utility owners, including Metro Vancouver and BC Hydro. These permits are required before performing work within a 98-feet (30-meter) proximity of active utilities. Such work includes working in parallel, working above or installing a new pipeline crossing below a utility.
For both the 2018 and 2019 construction seasons, permits were obtained to close lanes on municipal roadways to construct the pipeline. Michels secured 78 different lane closure permits (33 preconstruction and 45 for pipeline installation). In addition to the lane closure permits, Michels obtained six separate third-party utility permits to perform work in proximity to the owners’ utilities.
The project management team has a full-time dedicated scheduling resource assigned to plan, monitor and report progress. As plans are constantly being altered to facilitate the changing working conditions due to new underground utilities, and preexisting damaged or aging infrastructure, full-time scheduling has been a big part of the current success.
While the schedule is only published once per week, there are several schedule sessions with the senior management staff on-site to assist in mitigating ongoing issues and changes in construction conditions.
Logistics
The majority of the project consisted of short construction segments combined with a narrow workspace, consisting of a travel lane and the excavation.
Having been restricted to the roadways for workspace, at best the construction workspace side is only 9.8 feet (3 meters) wide. With this limitation and the addition of overhead power and communication lines in the work area, the necessity to choose the right size of equipment becomes more important. As such, the use of zero swing excavators with quick attachment couplers was an integral part of working within the smaller workspace closures to not impede any outside traffic.
Outside of self-performing the trenchless road crossings with an auger bore machine, once construction moved into full swing, the Michels team used in-house equipment, such as hydrovac trucks, zero swing excavators equipped with rubber track pads to minimize asphalt scouring, coring units and vibro-sheet-piling installers. This equipment was mobilized from yards or purchased specifically for the project and utilized by Michels personnel directly.
Means, Methods
Due to a large percentage of work being done in a traditional open-cut method requiring standard backfill methods consisting of granular fill and forms of mechanical compaction, Michels proposed the use of controlled density fill (CDF), also commonly referred to as flowable fill or slurry backfill, to lessen the scheduled impact time required to return street sections back to service.
The CDF has been designed to allow excavation in the future while also providing a 28-day compressive strength of 72.5 psi (0.5 MPa). Used as an alternative to traditional aggregates, CDF accelerates the backfilling activity process by eliminating the need for mechanical compaction around the pipe and adjacent utilities.
CDF also eliminates the high- and low-frequency vibrations in the urban environment, which may lead to damaged adjacent property claims (including heritage buildings), broken utility claims and subsidence within the permitted right-of-way (ROW).
One truck delivered to the site holding about 283 cf (8 m3) of CDF, which could be unloaded in 3 minutes, resulting in a reduction in time of up to 75%. On some occasions, up to 80 truckloads (22,601 cf [640 m3]) of CDF were poured for one backfill location. Nonetheless, aggregates were used in the top 27.6 inches (700 mm) of the trench.
By eliminating the need for densify backfill and bedding aggregates around the new pipe, the use of CDF eliminated the risk of inducing ovalities (out-of-round pipe) caused by over- or uneven mechanical compaction.
This change required separate physical and analytical demonstrations to gain approval from each of the three cities’ utility departments.
Utility Locations
Contract plans and drawings identified crossings of 1,716 underground utilities. Once the onsite preplanning started and crews were dispatched to conduct the sweeps and daylighting activities, it was determined that an excessive additional amount of new underground utilities would be crossed and discovered. To date, that number is approximately 450.
To perform the daylighting activities, traffic management plans were constructed in conjunction with a traffic management subcontractor. These plans were specific to street locations to implement temporary, short-term closures. These are completed well in advance of the construction crew’s arrival to allow the field engineers time to predesign possible alignment changes due to conflicts with the additional previously unknown underground utilities.
In 2018, Michels self-completed nine trenchless road crossings ranging from 115 feet to 154 feet (35 meters to 47 meters) in length. In 2019, a minimum of eight trenchless crossings were self-preform from 102 feet to 187 feet (31 meters to 57 meters) in length and one was subcontracted.
These bores utilized the installation of engineered slide rail shorings due to the depth of the bore entry and exit pits being upward of 20 feet to 23 feet (6 meters to 7 meters) deep. The slide rail designs vary from 23 feet to 66 feet (7 meters to 20 meters) in length and approximately 9.8 feet (3 meters) in width. The shoring designs were created to ensure the crews had adequate room to safely perform the duties associated with the trenchless crossing. Direct Equipment West has assisted Michels in engineering the slide rail shoring designs using Pro-Tec Shoring equipment.
Environmental
The overall topography encountered along the project route consists of many hills and slopes, the majority of which are asphalt and concrete surfaces. This presented several challenges, including surfaces that do not allow for the infiltration of precipitation (surface water), limited opportunities to divert clean water around the work site and impervious surfaces combined with several adjacent storm drains that lead directly to a downstream fish habitat. Worksites needed to be created that were proactively managed to ensure that there will be no adverse environmental effects from construction activities.
Nuisance excavation water, removed from excavations to successfully complete the installation of the gas line, presented similar challenges. Because the option to discharge to vegetation does not exist, nuisance excavation water must be clean enough to meet municipal guidelines for the discharge into the storm sewer system or transported offsite to an approved location.
Surface water diversions were installed along the boundaries of the worksite to promote clean water from entering the active worksite. Erosion and sediment controls were installed on all active sites to further manage the effects of excavation. Storm drain protectors (silt sacks) are installed in all storm drains that may be potentially affected. In certain circumstances storm drains are also covered, plugged or diverted to prevent the release of sediments to the storm sewer system.
Paved surfaces were kept clean by a combination of manually sweeping with brooms and mechanical sweeping. Keeping work surfaces free of excess sediments prevents sediment from being tracked out to municipal roadways and prevents offsite release to catch basins during rain events.
Nuisance excavation water required active treatment with a flocculating agent and settlement to meet municipal guidelines for the discharge of water to the storm sewer system. This method is successful, but requires holding capacity, settling time and space, all of which are difficult to accommodate within a limited workspace.
Because the project alignment progresses through areas that have previously been highly disturbed, the potential to encounter previously contaminated soils exists throughout the entire alignment. Service stations, repair shops and other industrial businesses exist or have existed along the project route. A preconstruction soil and water investigation was completed to identify areas of potential environmental concern (APEC).
No contamination was identified during the preconstruction investigation, but some APECs have been identified. Field personnel are educated on identifying potentially contaminated materials during excavation activities. When excavated material is identified as potentially contaminated, onsite work is to stop, the material is sampled and submitted for analysis, and a third-party consulting firm field screens the soils. Soils deemed contaminated are disposed of at a licensed facility and noncontaminated soils are transported to a clean fill receiver.
Quality Control
The LMIPSU Spread 3 (Vancouver) had zero indications of any anomalies that would have caused a rejection of in-service. These rejections include such things as oval pipe outside tolerance limits or dents. There are many factors that contributed to this success. Among them are the use of CDF backfill, the bending crew’s ability to bend pipe and swab each bend to ensure that the pipe’s ovality was within tolerances, and the removal or repair of any identified physical defects to the pipe prior to installation.
There are a total of 1,838 welds completed and there were only 11 repairs, for a 0.6% repair rate. This can be attributed to the craftsmanship and professionalism of the welders, foremen and pipe fitters hired for the project. The welding procedures developed by Michels for the SMAW (shield metal arc welding) process presented the welders with a broad range of variables to allow them to weld at their own specific comfort level.
One of the many challenges that presented itself to the team was the limited space in some of the trench boxes used to safely support the excavations, but welders planned an approach to each weld, including using left- and right-handed welders, and taking the time and proper precautions to ensure a successful completion.
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