In the last two years there have been ups and downs in many industries due to the COVID-19 pandemic. One of the industries that has survived, and in many cases thrived, is the trenchless construction sector. While there have been noticeable dips in the oil and gas arm of the industry, the municipal side of things has certainly proved steady.
Why is this? Simply put – clean, safe and reliable water service is a must. From source to tap to treatment, system owners are working diligently to ensure their underground infrastructure is up to date. Those who work on these systems were deemed essential in the early stages of the pandemic and that work has not let up.
According to the 2019 Canadian Infrastructure Report Card — produced by the Federation of Canadian Municipalities (FCM) and seven partner organizations — 30 percent of water infrastructure (such as watermains and sewers) are in fair, poor or very poor condition. When it comes to the rehabilitation and installation of this infrastructure, trenchless shines as a less disruptive alternative to open-cut methods.
To get an idea of what system owners are doing when it comes to trenchless works across Canada, we present our annual system owners roundtable feature. Taking part in our 2021 discussion are:
Mike Jokic, P.Eng
Senior Project Engineer
Metro Vancouver – Vancouver, British Columbia
Design and Construction Engineer
City of Winnipeg – Winnipeg, Manitoba
Senior Project Manager, Public Works
City of Hamilton – Hamilton, Ontario
Roger Levesque, P.Eng
Halifax Water – Halifax, Nova Scotia
Briefly describe your water/sewer system and its condition. What is unique about your system and/or the way it operates?
Jokic – Metro Vancouver’s (MV) sewer system comprises approximately 389 km of gravity sewers, 121 km of full sewers (12.6 km of river crossings, 82.8 km of forcemains, 14.8 km of pressure sewers and 11.5 km of siphons), 33 pump stations and five treatment plants. Our drinking water comes from rainfall and snowmelt in three mountain watersheds. The regional water system also includes five dams, two water treatment plants, 26 in-system storage reservoirs and tanks that refill on a 24-hour cycle, 19 pump stations, eight disinfection facilities, and over 520 km of transmission water mains ranging from 35 cm to 3 m diameter.
The condition of our sewer and water systems is varied. There are new assets in excellent condition, aging assets that require more frequent inspection, maintenance and repair, and assets nearing or at the end of life that need replacement or extensive rehabilitation. Regionally, MV’s sewer system is somewhat unique with respect to the size of our sewers (large diameters in comparison to municipal systems). Also, as we collect sewage from local municipalities, we are required to convey and treat whatever is received from the municipalities. Issues in tributary municipal systems that MV has little control over can have a significant impact on our system – inflow & infiltration (I&I) and fats, oils and grease (FOG) for example.
Zurek – The City of Winnipeg Sewer and Water collection and distribution system consists of approximately 2,600 km of waste water collection sewers of which 9 per cent are considered to be poor to very poor. There are 1,400 km of land drainage sewers with 19 per cent considered to in the poor to very poor range. The water supply and distribution system consist of over 3,000 km of pipe with approximately 12 per cent considered to be in poor to very poor condition.
Zantingh – The City of Hamilton operates 2,125 km of watermain and 3,100 km storm/sanitary/combined sewer. Our system is unique as 90 per cent of the system is treated at the Woodward Treatment. Another point of interest is the escarpment giving elevation to transmit sewage via gravity. Reducing the number of sewerage pump stations. The escarpment also provides good elevation for water storage facilities.
Levesque – Halifax Water is unique in providing water, wastewater and stormwater services under one utility serving the residents of the Halifax region. As one of the oldest cities in Canada, Halifax has sewer and water infrastructure dating to the mid 1800’s. As such, Halifax Water is focused on long term planning to address aging infrastructure.
What are the main problems you are facing with your system?
Jokic – I/I, root intrusion and FOG are all ongoing problems, not only in MV’s system but especially in tributary municipal systems. Grit collection/sedimentation and H2S corrosion are also an issue in parts of the sewer system. Maintenance and repair such as root cutting, flushing/debris removal, and grout injection are much more challenging in larger diameter pipes. Technologies that can be extremely effective in smaller diameter pipes are not always effective in larger diameter pipes.
Zurek – Continual maintenance and repair of the sewer and water system are the biggest challenges facing the city.
Zantingh – A concern that we have is the maintenance of our sewage drop structures at the escarpment crossings. These structures are major features in the collection system. The structures are 50 m high and are located on major sewers with high flows, limiting the ability to divert flows. Making it challenging or not possible to complete a proper inspection on them.
Sewers installed in environmentally sensitive areas continue to be difficult to manage. Accessing these assets for inspections or maintenance is a challenge. Working on solutions to rehab them requires time to complete environmental field studies and temporary access roads.
Levesque – Given the vintage and age of most assets in our system, the items queried [I&I, FOG and root intrusion] all form part of our ongoing maintenance regiment and tasks to maintain our infrastructure.
What specific trenchless technologies do you use? How has your use of trenchless technologies changed over the last few years?
Jokic – For new installations, Metro Vancouver has used conventional tunneling, microtunneling and horizontal directional drilling (HDD) mostly. For rehab and repair we mostly use cured-in-place pipe (CIPP) and sliplining. Recently we have been using Microtunneling more as the technology improves and open cut work is less desirable.
Zurek – CIPP of sewers is a major component of our trenchless technology approach to the maintenance and repair of existing sewer systems. Trenchless technology has been used for the installation of new, large diameter, land sewers by microtunnelling techniques. HDD has been used on some of river crossings for both sewer and water facilities.
Zantingh – The City of Hamilton has used CIPP, grouted in-place (GRP) panel lining and sliplining on existing assets. For new installations tunnelling and HDD have been used. CIPP is our preferred solution for rehabilitation of exist pipes. GRP panels are used when the pipe cannot be lined by a CIPP liner.
Our program in the last several years has expanded to use different methods due to the size and shape of the pipe. As our focus shifts to larger more critical pipes, CIPP isn’t always possible and other structural rehabilitation methods are required.
Levesque – We have used CIPP for lining of watermains to a limited degree since in the late 90’s. The current trenchless technology used mainly at our utility is the CIPP lining of wastewater sewer mains. To date, we have used mostly steam and hot water liner inversion cure methods however recent programs were also conducted using the latest pulled liner and UV-cured method. We have also conducted several lateral lining programs utilizing both the manhole to home CIPP lining method, as well as the clean-out at the property line entry method. Manhole rehabilitation using an epoxy spray coating application method is also used.
Our best success has been with mainline lining, and we have found there have been advantages and disadvantages with each type of CIPP application. The steam and hot water cure inversion methods tend to be quicker and the operation faster than the UV operations. However, [with steam and hot water cure] the footprint of the required install and curing equipment, in our experience, typically can be up to three times larger. This equipment’s larger footprint often makes it a challenge for street work and managing traffic flow in smaller streets of the older parts of our municipality. On the other hand, the UV CIPP operations tend to take longer to install thus slower, but the work layout’s footprint is much smaller. In the end, the results of final liner product qualities obtained from each are very similar and both methods tend to somewhat evenly work out when all constraints are factored in. The UV lining method as well has an advantage with tight easement sections where access is often limited. Despite the larger footprint of the steam or hot water cure method, in our experience the contractor can often introduce innovative solutions to get the lining completed.
Going back about seven years when the mainline lining program was re-initiated first as a pilot, we have since completed successive annual CIPP lining programs. The annual budgets for these trenchless programs have increased four- fold over this timeframe and increasingly targeting not only the rehabilitation of ageing infrastructure but as well to provide solutions for reducing I&I in the system.
Do you perform any trenchless work in-house or is it all contracted work? What have you learned from your experience with trenchless technologies?
Jokic – All of Metro Vancouver’s trenchless work is contracted out. For new installations, we have learned the value of a rigorous feasibility study prior to design and ensuring the Geotechnical Baseline Report is solid. We believe we’ll see many more projects using trenchless technologies in the future.
Zurek – All our trenchless work is contracted. Trenchless rehabilitation and installation of new infrastructure will continue to play a major role for the future City of Winnipeg projects.
Zantingh – We do not do any inhouse rehab. All rehab work is completed by contractor.
With the use of trenchless methods, a municipality or utility can renew large areas in timely and cost-effective manner. Whole neighbourhoods can be targeted with little to no service disruption. It’s hard quantified the social cost advantage of trenchless but remains to be one of largest benefits.
An example of this, we notified a ward Councillor about a large sewer lining project happening in their ward. Approximately 4 km of sewer was scheduled to be lined. The lining operation went almost unnoticed. We received a call four months later from the Councillor asking when the work will take place. It had already been done for two months at time of the call. Conversely, conventional open cut replacement would have taken two construction seasons to complete and had much great impact of the residents in the area.
Trenchless technologies have been large part of our capital program for sewer and water. It has social and environment benefits over open cut methods, helping to solve our infrastructure backlog. If we hadn’t been as aggressive in our lining programs, we would have seen major increase in maintenance cost on sewer mains, sewer laterals and break repairs on water. The City of Hamilton will continue to use trenchless technologies to renew our aging distribution and collection networks.
Levesque – We have developed the capability to complete CIPP trenchless point patch repairs on problem pipe sections. All the other trenchless lining works are contracted out.
Having used CIPP at various stages over the past 20-plus years, over the past seven year we have been successful with conducting annual rehabilitation programs. The primary benefits and experience of CIPP have been realized to provide and restore flow capacity and to restore structural integrity of ageing and challenged sewer mains which were making them prone to disruptions at a fraction of the cost. The CIPP process has proven to offer us minimal impact on the surrounding environment and to offer a permanent solution to pipe deterioration, and by this process instrumental in controlling pipe infiltration, and ex-filtration. The very fact that the entire process is trenchless and not requiring excavation makes it more cost effective, less time consuming, and environmentally friendly. It also offers the benefits of providing long term complete structural rehabilitation of the sewer. CIPP main rehabilitation provides the same structural strength of conventional brand-new pipe. The cost savings of CIPP has realized both short and long-term life cycle advantages. The streamline and innovated trenchless installation process further reduce the cost of labour associated with traditional methods. Additionally, restorative landscaping and infrastructure reinstatements as typically needed with excavation methods are largely negated.
In the future, as we see the trenchless methods and applications expanding as technologies advance, we anticipate the continuation of annual trenchless rehabilitation programs.
What are the limiting factors in keeping your system in peak condition?
Jokic – The main limiting factor affecting Metro Vancouver’s water and sewer system is funding. The current repair or replacement issues with the aging assets in the system are mostly due to of the lack of funding in the past.
What changes are occurring in the way the public utility systems are operating?
Levesque – A challenge is not fully knowing the overall state of the infrastructure conditions. We are increasingly investing in asset management initiatives which strive to expand on the collection of infrastructure condition information of our assets. These include additional CCTV and related inspection efforts to obtain information to improve our ability to understand and to triage the rehabilitation of areas in need. There is an increasing focus based on obtaining PACP and related data as part of inspections.
Initiatives are now under way to identify areas of concern and to target areas for further investigation and to identify sewer lining candidates. This information will focus to better enable the utility to understand the overall infrastructure renewal needs. Currently, detailed design and candidate pipe segment selections are largely based on a comprehensive review of CCTV data, operational experience, integration opportunities, etc. In the future the PACP ratings and related benchmarks will form an increased basis to establish more comprehensive rehabilitation programs.
What are some of the unique approaches your organization has taken to solving its infrastructure problems?
Zantingh – The City of Hamilton use multi-year contracts for its lining program. They are issued as a price per point evaluate Request for Proposal (RFP). Giving the ability to get the best valve for money. We ask the vendors to submit a proposal and the tender bid in one package. This the tender bid remains sealed until the proposal is evaluated. An evaluation team reviews and grades the vendors proposal. If the vendor has a passing grade the tender bid is then opened. The price per point is derived by dividing the grade of the propose by the vendor’s tender price. The contract is awarded to the vendor with the best price per point.
Levesque – From the onset with our trenchless programs, we have engaged and continue an association with leading trenchless engineering consulting resources in the industry to guide and provide support on the latest trenchless knowledge and related specifications.