SIGMA Corporation is proud to announce the completion of a major irrigation and construction project in southern British Columbia, Canada. Designed and managed by TRUE Consulting, a civil engineering firm located in central British Columbia, the Gallagher Low Head Siphon Project represents the first Canadian installation of SIGMA’s 60 inch restrained joint system for AWWA C900 PVC pressure piping.
As a world leader in large diameter pipe restraints, SIGMA introduced the 1st-ever 54” and 60” PVC pipe joint restraints for both Canada and the U.S. In this instance, SIGMA worked closely with Alberta-based Ipex, the only national Canadian company producing these large diameter size PVC pipes.
The Gallagher project is a major feat of engineering. The project, which has taken nearly four years from design to construction, will be fully operational in time for the irrigation season in April 2022. The project is named after the famous Gallagher bluffs, an area of great beauty, and distinguished by a 100-year-old canal water management system, serving one of the most productive agricultural region in Canada. The area is also famous for the Okanagan Valley vineyards – Canada’s equivalent to the Napa Valley. Water management is critical as this area receives less than 12 inches of rain a year.
The construction project was broken down into three main components. The first involved replacing the existing siphon under Vaseux Creek using eight-foot diameter concrete pipes; the next phase involved building a “lift station” structure that added 9’ of hydraulic head and then installing approximately 1300m (4265’) of 1500mm (5’) diameter C900 PVC that will then join to the existing canal. TRUE Consulting concluded it was not cost-effective to replace the entire diversion with an eight-foot pipe due to the high cost and the profound disturbance to local infrastructure when installing the large diameter pipe. The solution was to build a lift station that would add sufficient hydraulic head to ensure the smaller 1500mm PVC pipe could convey the entire canal capacity. The lift station was also designed to let the irrigation water pass through without adding hydraulic head when the demand for water is lower (during spring and fall). At its lowest point, this replacement siphon drops 14.15m (46.4’) from the open canal water elevation with a maximum gravity operating pressure of 20.0psi or 22.8psi when the lift station is active. The C900 PVC pipe has the capacity to handle up to 150psi.
The new system replaces the ground level open canal and a buried, concrete-capped section that was built close to the base of a near vertical 250m (820’) high bluff. This section of the canal had been crushed and repaired several times previously. The last major rock fall was a fragment of rock the size of a small house and it caused considerable damage. The project was complicated by the geography and weather as the area consists of mountainous, desert terrain and is subjected to extreme weather and ground conditions. The temperatures in this area can reach up to 45 degrees Celsius (113 Fahrenheit). Portions of the canal replacement, including the lift station, could only be constructed when the canal was closed for winter between November 1st and April 1st. Winter temperatures can dip to -20 degrees Celsius which makes any earthworks near impossible.
The consulting engineers investigated numerous designs before selecting the lift station combined with the smaller diameter pipe option. The new replacement siphon diverted sharply from the original route so land was purchased from adjacent owners. The route twice crossed a major highway and was routed along a narrow stretch of land between a highway and a paved frontage road.
As the leading supplier of pipe restraint products in North America, SIGMA Corporation was selected to provide many of the key fittings and essential pipe joint restraints for this project. SIGMA supplied the 60” joint restraints, 60” mechanical joint end caps and 60 x 36” mechanical joint x flanged tees, in addition to portions of the project that required 60” bell x spigot pipe bell restrainers for the Ipex C900 PVC joints for installations under highway.
SIGMA was also involved with troubleshooting and providing technical support in the onsite preparation of mechanical joint sleeves and mechanical joint restraints. Rob Mathews, SIGMA’s Territorial Sales Manager for the area, was instrumental in providing onsite assistance throughout the project.
Dorian Fischer, TRUE’s Civil Engineering Technologist, who designed the siphon and inspected the construction to date, explained the design process behind their decision: “We investigated tunneling through the adjacent mountain, but it is composed of gneiss, which is an extremely hard rock, so it wasn’t a cost-effective option. We researched multiple pipe materials, including a pressured fiberglass polymer pipe, but we needed the flexibility to go under roads and around other utility pipes and cables, with minimum disruption. Our final iteration consisted of a concrete pipe under a creek, joining a lift station below ground and then conveyed by the 60” C900 PVC to a connection point on the old canal. The total distance from new inlet to the new outlet structure is 1470m (4825’).”
The scale of the installation is impressive; the contractor, H&M Construction, dealing with extreme weights and handling requirements when using the concrete pipe sections. Fischer adds, “each pipe section weighed more than 25,000 lbs and needed to be lifted and moved in concert by two large excavators. We were working in a creek bed and each section had to be gently but forcefully seated to the previous section and to stay on the design alignment.” The project also crossed a major highway twice and provincial regula- tions required a steel casing the full width of the road. Thus, appropriate casing spacers were specified which offset from the outside of the 60” PVC pipe to the casing “wheels”, which then dictated the inside diameter of the steel road casing (84” diameter). Within the casing pipe, SIGMA restraints would play a prominent role. The contractor had to install the joint restraints at the casing end and then “roll” that section into the casing just enough to restrain the next section. The steel road casings were up to 69-ft long.
Commented Dorian: “SIGMA’s team, led by Rob Mathews and Satheesh Chandrasekaran, head of SIGMA’s pipe restraint engineering department, suggested numerous creative ideas including that we should double nut each side of the restrainer ears so we were able to push it through and pull it back again while keeping the pipe stabilized. Typically, pipe bell joints have retaining nuts on the outside of the restrainer ears; in this instance, we added nuts to the inside of the retaining ears, thus ensuring greater stability during installation.
According to the team at TRUE, installation went smoothly, and the system is working perfectly. TRUE also specified two pressurized access hatches to allow access for cleaning and inspection of the pipes’ interior for future maintenance and services when required. Dorian mentioned “because of organic matter, we needed to be able to access and clean the inside of the lines, thus we opted to install SIGMA’s 60” x 36” mechanical joint by flanged tees.” These entry-way configurations were also supplied by SIGMA Corporation.
Key players on the project included:
Consulting Engineers, TRUE Consulting of Kamloops, British Columbia Contractor, H & M Construction of Penticton. B.C.
Distributor Wolseley Canada (Jake Jackson, Branch Manager – Kelowna)
The Civil Engineering project team at TRUE included:
Steve Underwood, Senior Project Engineer Dorian Fischer, Civil Engineering Technologist Natalie Alteen, Project Engineer
For information about SIGMA’s pipe restraint products, please contact National Pipe Restraint Sales Manager Steve McDonald at smd@sigmaco.com.