CSPI

The Right Stuff: Timeliness and Teamwork Keys to Emergency Infrastructure Repairs in Environmentally Sensitive Locations

On Saturday afternoon, May 24, 2014, a portion of Victoria Road, in Guelph, Ontario collapsed without warning, resulting in a hole in the southbound lane, roughly 1.7 metres wide and 6 metres deep. Despite the media incorrectly reporting the incident as a sinkhole, as the investigation unfolded, city infrastructure specialists discovered the washout was actually caused by the collapse of an underground concrete box culvert which had been installed in the 1920s or 30s.      

The manner in which the City of Guelph responded to this infrastructure emergency offers all of us insight into how to do things right. Through a combination of preparedness, organization, collaboration and communication, Guelph’s Engineering Services personnel were able to accurately identify the root cause of the collapse, develop an integrated restoration strategy and repair the problem – all with minimal disturbance to citizens and the indigenous wildlife in the wetland areas adjacent to the site on both sides. The success of their comprehensive, well-orchestrated procedures and actions offers an excellent example of efficiency in addressing a wide variety of stakeholder issues in a timely manner, which is often the case with complex municipal infrastructure emergencies.

“Sinkholes sell newspapers because they terrify people,” says David Penny, former Executive Director of the CSPI, who immediately traveled to the site to help assess the problem. “At first, it may have looked like a sinkhole, but true sinkholes involve things disappearing over time, into underground streams – a phenomenon affiliated with karst topography, in which underground streams erode and carry away the soluble rock, such as limestone, dolomite, or gypsum, that previously supported the ground above and trigger a collapse. However, when this kind of symptom occurs near a CSP installation, it’s more likely a ‘washout’ of some sort, caused by a failed infrastructure component in a water management system,” he adds.

According to Grant Ferguson, Manager of Technical Services, City of Guelph, the first problem facing his team was determining the true nature and cause of the collapse, which occurred Saturday afternoon. On Sunday morning when the City’s repair crews began excavating the site, they soon noticed an old, exposed CSP pipe, assumed it caused the collapse, and proceeded to backfill the collapsed area.

When Ferguson arrived at the site, Monday morning following the collapse, he had anticipated that perhaps a simple road restoration could complete the work. However, after a discussion with his operations crew, he realized they would need to re-excavate the road and investigate the condition of the CSP the crew had seen the previous day, before they could be certain of what caused the collapse.

“Fortunately, for emergency situations such as this one, I have a short list of contractors on a Rotational Roster Bidders list, through the City Purchasing Department,” explains Ferguson. “I knew I’d need to contact each contractor individually to see if their schedule was clear, so they could mobilize immediately. My initial guess was this repair would likely entail a three or four week permit process, followed by two or three week of road restoration,” he adds.

“On Monday morning, after I’d been briefed by on site personnel regarding their initial investigation and comments regarding the CSP structure partly visible below, I knew I’d need to get a look at the structure to better assess and confirm the cause of the collapse,” says Ferguson. “But, by the time I attempted to enter the outermost 1800mm CSP pipe, the wetlands on the east side had already begun to retain water and it was difficult to actually get into the pipe. On the west side, the CSP allowed very limited access, and I could see that the granular materials had collapsed about nine metres into the culvert,” he adds, “but, unfortunately, that still didn’t tell us much.”

Later, however, as the crew began clearing the area through excavation, they discovered that the 1800mm CSP, which they originally believed was a single, continuous length of pipe, had actually been threaded into (or over fit by) a second CSP pipe, 2200 mm in diameter. As they continued to excavate to the end of the 2200 mm CSP, they then discovered that the true source of the collapse involved an existing concrete structure that had failed where it was joined to the 2200 mm CSP.

“Adding new infrastructure to aging, legacy infrastructures may at times seem an economically attractive solution, but incompatibilities, or jury rigging disparate components together can cause serious problems down the road, and is something we see quite often with aging installations,” explains CSPI Executive Director, Ray Wilcock. “In the past, it was fairly common to extend old infrastructure by simply adding new infrastructure to the existing one. But, problems are often very difficult to assess if they occur somewhere other than near the end of the pipe, which was the case here. Following the collapse, Dave Penny had inspected the existing galvanized CSP pipes and found they were still in good condition, with lots of life left in them.

“But of course it wasn’t possible to determine the condition of the pipe at its middle; there may be a problem, but you simply can’t know for sure,” continues Wilcock. “For that reason, many regulatory bodies, including MTO, no longer allow the mixing of different materials in a single installation. Rather, they want to encourage the continuity and simplicity offered by the use of compatible, contiguous materials, throughout the entire installation; for example, you may not use concrete at one end of a culvert and CSP at the other,” he adds.

Originally, the concrete structure had likely been installed to span a small creek or waterway between the two wetlands. Although the parapet wall on its west side remained intact, the east parapet had been removed sometime in the past – probably in the 1960s when the road was widened – to enable the addition of the 2200 mm CSP. However, because the new CSP had been poorly fitted to the existing concrete structure, it inevitably began to leak and, over time, the surrounding fill and concrete structure both continued to erode, culminating in the washout that triggered the road collapse, above.

Although Victoria Road southbound had been closed on Saturday, when the collapse was first discovered, it wasn’t until Monday – after the true cause of the collapse had been determined – that Guelph and County of Wellington officials ordered a full road closure and provided traffic detour routes both in and out of the City and County.

“At that point we didn’t fully understand the extent of the collapse,” says Ferguson, “but, since Victoria Road is an important thoroughfare, as well as a designated truck route, I knew we had to get more definitive answers as to what had transpired, make some decisions and get the road re-opened as quickly as possible.”

Not Your A Run-Of-The-Mill Road Repair

Once Ferguson had a proposed restoration plan in mind, he immediately began phoning people he believed could offer the best assistance. “Initially, my primary concern was the physical rebuilding of the road and under structures,” he explains. “Of course, that necessitated we involve an engineering firm. Once that was in place, I began calling other stakeholders to brief them on what had transpired,” he adds.

Ferguson goes on to explain that, although the City of Guelph owns Victoria Road, in deference to the environmental sensitivity of the adjacent wetland areas, he knew this project would likely require the involvement of other agencies and authorities. So, his first order of business was to ensure all relevant stakeholders were apprised of the situation and kept in the communications loop.

“From my previous experience with other projects in environmentally sensitive locations, I knew that the wetlands on the east and west sides of Victoria Road both fell under the jurisdiction of the Grand River Conservation Authority (GRCA),” says Ferguson, “so I called them first and arranged for an on-site meeting, Monday at noon, to review their concerns and determine what permits might be required by the City.

“Of course, we needed to pump water to access to the buried structures,” says Ferguson. “So, my next call was to the Ministry of the Environment (MOE), in regard to granting us permission to proceed, with a provision that the Permit To Take Water (PTTW) would be under review and monitored, due to the emergency nature of the problem. MOE met with us on Monday and were extremely responsive and helpful,” he adds.

Enter the Turtle…

Adding to the confusion immediately following the collapse, on Sunday May 25, a mother snapping turtle was observed trying to build a nest on the west side of the backfilled area of the collapse. Numerous passers-by had taken photos of the snapping turtle at the site and posted them to Facebook and there was some rumours that she had laid eggs.

“Ah, yes, the snapping turtle!” says Ferguson with a laugh. “Well, she certainly added a new twist to what was already a rather complex situation.”

Snapping turtles are currently designated as a species at risk, and are thus of special concern to the Ministry. With this in mind, Ferguson was referred to a Wildlife Ecologist at MMM Consulting Engineers who could help supervise any on site work required to protect the turtle and its nest during the project. MMM, in turn, immediately contacted the Ministry of Natural Resources (MNR) to gain permission to assist the City with the snapping turtles, if necessary.

“Because she had extensive research experience with Snapping Turtle habitats, MNR gave the MMM Wildlife Ecologist immediate permission to re-locate the nest some 20 metres away from the work zone,” explains Ferguson, however, after examination, no eggs were found and it was determined to have been a ‘test nest’,” he adds.

With the understanding and timely cooperation from all stakeholders – including the citizenry, regulatory authorities, relevant ministries and bodies at all three levels of government, MMM Engineering and Armtec (who manufactured the new replacement CSP) – the team was able to complete a very successful and timely restoration.

“It was quite an intense project,” says Ferguson, “We closed Victoria Road south on May 24, 2014 and re-opened it June 13, 2014 – just three weeks later. But, we couldn’t have done it on our own,” he explains. “It was only possible because all regulatory agencies were quick to respond to our dilemma. In fact, the permit processes proceeded alongside the actual restoration and at the end of the day all parties pulled it together. It was a tremendous effort on the part of everyone involved and they all deserve a great deal of credit. We all worked cooperatively with each other and we got it done a day ahead of schedule,” summarizes Ferguson.

As the existing CSP extensions were found to be in good condition, the original thought was to keep them in place and only replace the concrete structure. However, after more discussion, it was decided that replacing the entire length of the 32 metre culvert was a much more prudent and efficient long-term solution.

In order to meet the contractor’s very tight construction schedule, Armtec was selected to supply the required 32 metres of 1800 mm diameter CSP within days. The entire length of pipe was 2.8 mm thick galvanized CSP, in the 125 x 25 mm corrugation profile.

In the end, the entire project, including excavation, replacement, and re-paving, was completed earlier than anticipated, and Victoria road was re-opened a day ahead of schedule.

All In A Day’s Work

“In my position with the City as Manager of Technical Services, I encounter many, many situations where the norm requires that we conceptualize or create a good solution to an uncommon situation or problem,” explains Ferguson. “I get personal satisfaction from being in the midst of pulling together whatever agencies, persons, groups or resources we’ll need to include, in order to come up with a clear and plausible plan to repair, restore – or whatever – and have that solution come together successfully, at the end of the day,” he adds.

“This project was a true collaboration of all parties involved – not just with lip service, but with actions,” summarizes Ferguson, “and working together really did enable us to make better decisions, easier and faster. As a municipality, we generally get lots of inquiries as to why and how we intend on doing a particular project. As with most Environmental Assessment and capital projects, the City of Guelph welcomes dialogue with its citizen, and hosts open house sessions to encourage the public to pose questions, or provide their input and suggestions regarding specific projects,” he adds.