Canadian Underground Infrastructure Logo

When the waters get rough, seek smart solutions

When the waters get rough, seek smart solutions

Fighting upstream against turbulent currents is difficult enough. But spawning salmon in British Columbia must also swim through tens of thousands of failing manmade culverts that impede passage due to increased water velocity, washout, and maintenance issues.

And that only counts crossings that include the highest quality habitats, priority fish species, and those that need immediate attention, according to a paper documenting fish passage issues by Ian Miller, chair of the Fish Passage Technical Working Group (FPTWG).

With about 550,000 resource roads in B.C. and an estimated 320,000 crossings of fish streams on those roads, about 70 percent are closed-bottom culverts, Miller stated. “Of those closed-bottom culverts, about 60 to 90 percent are likely to impede fish passage.”

Addressing failing culverts

The aquatic and riparian conditions in B.C. affect not only the environment but also the finances of municipalities and individual residents. Whether for environmental reasons, tourism or business, it is clear that fish, and particularly salmon, are integral to life in this part of Canada. And impediments to their population, particularly manmade ones like failing culverts, need to be addressed.

“In West Vancouver, it is very hilly and mountainous, and there’s a lot of storm water that needs to be taken care of,” said Cameron Magnus, a civil design technologist with ISL Engineering and Land Services Ltd. “A lot of the storm water conveyances like culverts are failing, so we need to replace or address them.”

When Magnus’ firm was hired by the District of West Vancouver Utilities to help address a failing culvert in a tributary of Brothers Creek, they looked at a variety of solutions to the problem. The oval corrugated metal pipe culvert was old and past its design life. It had significant damage due to corrosion and was at risk of a collapse, which would negatively impact a salmon-bearing stream.

ISL worked with West Vancouver Utilities on this project to provide culvert design, environmental remediation, and monitor the stream prior to and during the entire installation process for any fish passage issues.

The primary environmental concern when working with a culvert that also serves as access for fish species is maintaining substrate and fish passage, said Marie Mattadu, an environmental scientist with ISL Engineering. “Those concerns are dealt with by minimizing culvert grade, introducing a simulated stream bed, tail water control, baffles or other internal control elements.” 

Mattadu’s role as an environmental lead in the field included isolation and removal of existing fish prior to construction, designing and monitoring the temporary stream-diversion, monitoring the stream chemistry during installation, and then monitoring the installation of baffles and redirection of stream back to its natural flow.

No-dig solution

ISL preferred a no-dig solution to excavating the corrugated metal pipe (CMP), which would avoid traffic and utilities disruptions, and restoration work that would impact access for residents. But above all, the primary reason to bypass an open-cut culvert repair was environmental concerns of fish passage and habitat.

“We needed a fish passage solution and wanted to avoid disturbing the creek as much as possible,” Magnus said. “An open-cut would have been too intrusive to the existing stream and adjacent vegetation.”

ISL chose ISCO Industries’ Snap-Tite HDPE pipe with retrofitted HDPE baffles as the best option to rehab the culvert and address fish passage issues. Snap-Tite’s use of HDPE was a distinct benefit in that the product is longlasting and allows on-site installation of custom baffle design. The oval shape was the major decision maker as it allows for maximum flow during highwater storm events, while the baffles help control velocity.

The culvert could not be replaced for this project, so added baffles will aid fish passage because they create complex turbulent flow which assist fish in ascending the culvert, create deeper water areas within the culvert where fish can rest periodically as they ascend the culvert, and help maintain substrate which contributes to complex flow patterns mimicking natural conditions.

And the process of slip-lining is the least disruptive to a natural stream habitat as it does not require any excavation. “Excavation can have a disastrous impact on stream habitats due to sedimentation that occurs downstream,” said Snap-Tite Regional Manager Steve Fischer. “The flow of the water will drag in silt and natural materials, and the baffles will help secure natural stream-bed material throughout the length of the culvert.”

HDPE pipe is also inert, which avoids the deterioration process that occurs with traditional culvert products like corrugated metal pipe (CMP). CMPs can change the chemistry of the water downstream as they corrode and break down, as well as lead to the accumulation of heavy-metals in the water associated with corrugated metal pipe.

The use of HDPE and Snap-Tite offered a non-disruptive and environmentally sound rehabilitation process and significantly improved the culvert’s longevity, extending the lifespan of the culvert up to 100 years. Magnus also installed tail-water control features using large riprap and built two ponds for fish to rest in prior to entering the culvert when swimming upstream.

For District of West Vancouver Utitlies Director Chris Zepedeo, and for ISL Engineering, this was their first fish passage job using Snap-Tite HDPE pipe. “It was a good idea and a good process,” Zepedeo said.

Once Magnus and Zepedeo decided on Snap-Tite, there was a small window in which to complete the project - literally a “fish window.” The fish window in B.C. is a narrow period of the year - August 1 to September 15 - where stream-remediation work is allowed to be performed in sensitive waterways. The fish window closes when fish start swimming upriver to spawn.

The West Vancouver Utilities crew completed the installation and installed the baffles, excavator services were provided by Christensen Excavation, and grouting was completed by Gastaldo Pumping. Magnus, Mattadu and ISL Engineering designed the culvert structure and provided environmental remediation.

“Having this in the ground is a benefit because other utilities can come see the success of this solution,” Magnus said. “I’d definitely recommend the use of Snap-Tite again.”

Snap-Tite HDPE pipe with retrofitted HDPE baffles was chosen as the best option to rehab the culvert and address fish passage issues.

Fighting upstream against turbulent currents is difficult enough. But spawning salmon in British Columbia must also swim through tens of thousands of failing manmade culverts that impede passage due to increased water velocity, washout, and maintenance issues.

And that only counts crossings that include the highest quality habitats, priority fish species, and those that need immediate attention, according to a paper documenting fish passage issues by Ian Miller, chair of the Fish Passage Technical Working Group (FPTWG).

With about 550,000 resource roads in B.C. and an estimated 320,000 crossings of fish streams on those roads, about 70 percent are closed-bottom culverts, Miller stated. “Of those closed-bottom culverts, about 60 to 90 percent are likely to impede fish passage.”

Addressing failing culverts

The aquatic and riparian conditions in B.C. affect not only the environment but also the finances of municipalities and individual residents. Whether for environmental reasons, tourism or business, it is clear that fish, and particularly salmon, are integral to life in this part of Canada. And impediments to their population, particularly manmade ones like failing culverts, need to be addressed.

“In West Vancouver, it is very hilly and mountainous, and there’s a lot of storm water that needs to be taken care of,” said Cameron Magnus, a civil design technologist with ISL Engineering and Land Services Ltd. “A lot of the storm water conveyances like culverts are failing, so we need to replace or address them.”

When Magnus’ firm was hired by the District of West Vancouver Utilities to help address a failing culvert in a tributary of Brothers Creek, they looked at a variety of solutions to the problem. The oval corrugated metal pipe culvert was old and past its design life. It had significant damage due to corrosion and was at risk of a collapse, which would negatively impact a salmon-bearing stream.

ISL worked with West Vancouver Utilities on this project to provide culvert design, environmental remediation, and monitor the stream prior to and during the entire installation process for any fish passage issues.

The primary environmental concern when working with a culvert that also serves as access for fish species is maintaining substrate and fish passage, said Marie Mattadu, an environmental scientist with ISL Engineering. “Those concerns are dealt with by minimizing culvert grade, introducing a simulated stream bed, tail water control, baffles or other internal control elements.” 

Mattadu’s role as an environmental lead in the field included isolation and removal of existing fish prior to construction, designing and monitoring the temporary stream-diversion, monitoring the stream chemistry during installation, and then monitoring the installation of baffles and redirection of stream back to its natural flow.

No-dig solution

ISL preferred a no-dig solution to excavating the corrugated metal pipe (CMP), which would avoid traffic and utilities disruptions, and restoration work that would impact access for residents. But above all, the primary reason to bypass an open-cut culvert repair was environmental concerns of fish passage and habitat.

“We needed a fish passage solution and wanted to avoid disturbing the creek as much as possible,” Magnus said. “An open-cut would have been too intrusive to the existing stream and adjacent vegetation.”

ISL chose ISCO Industries’ Snap-Tite HDPE pipe with retrofitted HDPE baffles as the best option to rehab the culvert and address fish passage issues. Snap-Tite’s use of HDPE was a distinct benefit in that the product is longlasting and allows on-site installation of custom baffle design. The oval shape was the major decision maker as it allows for maximum flow during highwater storm events, while the baffles help control velocity.

The culvert could not be replaced for this project, so added baffles will aid fish passage because they create complex turbulent flow which assist fish in ascending the culvert, create deeper water areas within the culvert where fish can rest periodically as they ascend the culvert, and help maintain substrate which contributes to complex flow patterns mimicking natural conditions.

And the process of slip-lining is the least disruptive to a natural stream habitat as it does not require any excavation. “Excavation can have a disastrous impact on stream habitats due to sedimentation that occurs downstream,” said Snap-Tite Regional Manager Steve Fischer. “The flow of the water will drag in silt and natural materials, and the baffles will help secure natural stream-bed material throughout the length of the culvert.”

HDPE pipe is also inert, which avoids the deterioration process that occurs with traditional culvert products like corrugated metal pipe (CMP). CMPs can change the chemistry of the water downstream as they corrode and break down, as well as lead to the accumulation of heavy-metals in the water associated with corrugated metal pipe.

The use of HDPE and Snap-Tite offered a non-disruptive and environmentally sound rehabilitation process and significantly improved the culvert’s longevity, extending the lifespan of the culvert up to 100 years. Magnus also installed tail-water control features using large riprap and built two ponds for fish to rest in prior to entering the culvert when swimming upstream.

For District of West Vancouver Utitlies Director Chris Zepedeo, and for ISL Engineering, this was their first fish passage job using Snap-Tite HDPE pipe. “It was a good idea and a good process,” Zepedeo said.

Once Magnus and Zepedeo decided on Snap-Tite, there was a small window in which to complete the project - literally a “fish window.” The fish window in B.C. is a narrow period of the year - August 1 to September 15 - where stream-remediation work is allowed to be performed in sensitive waterways. The fish window closes when fish start swimming upriver to spawn.

The West Vancouver Utilities crew completed the installation and installed the baffles, excavator services were provided by Christensen Excavation, and grouting was completed by Gastaldo Pumping. Magnus, Mattadu and ISL Engineering designed the culvert structure and provided environmental remediation.

“Having this in the ground is a benefit because other utilities can come see the success of this solution,” Magnus said. “I’d definitely recommend the use of Snap-Tite again.”

Company info

926 Baxter Avenue
P.O. Box 4545
Louisville, KY
US, 40204

Website:
isco-pipe.com

Read more