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D E C E M B E R 2 0 2 2 | 95 Bonnybrook WWTP Cogeneration Facility Expansion R EN D ER I N G CO U RT E S Y S TA N T EC BONNYBROOK WWTP COGENERATION FACILITY EXPANSION by NATALIE BRUCKNER C algary's Bonnybrook W W TP – the largest of Calgary's three wastewater treatment plants – has recently undergone an extensive upgrade and expansion to accommo- date the city's future growth and better protect the environment by taking bio- gas handling to the highest level. Through the Cogeneration Expansion Project, and in what is a first for Canada, the entire facility (which serves the communities north of Glenmore Trail in the city, as well as Cochrane, Airdrie, and the Elbow Valley) will be using all of its biogas as the primary fuel source to meet its needs for electrical power and indus- trial steam for its advanced treatment process. Interestingly, the facility is also the largest cold-weather bio- logical nutrient removal plant in the world (meaning influent tempera- tures reach a minimum of 10-degrees C with air temperatures as low as -40 C in the winter). "This project is aligned with our corporate energy plan, which includes conserving energy, improving effi- ciency, and reducing greenhouse gas emissions," says Jifan Liu, the City of Calgary's project manager. "Biogas is a by-product of our wastewater treat- ment process, so we have the biogas. We should harness it to no longer flare and use it to produce energy. Otherwise, it goes to waste." The Cogeneration Expansion Project is just one part of a bigger portfolio of projects and yet incredibly complex, consisting of construction and commis- sioning for the facility and upgrades to existing reciprocating engines. Originally built in the 1930s, the facility has undergone numerous upgrades over the years, however, the two-tiered expansion of the Cogeneration Facility has been archi- tecturally designed to blend into the existing buildings at the W W TP. "The frame of the cogenera- tion expansion building is concrete including a structural concrete roof due to the weight of the external air handling units, heat exchangers, and exhaust stacks. Translucent walls on the side are also a nice feature as they allow natural light to stream into the building," says Cedric McIntosh, proj- ect manager at Graham Construction. Inside, Kyle Jensen, electrical engi- neer at Stantec, describes the building as "a large space with ultimately two rooms and a control room. It was essential to maintain the appropriate segregation from hazardous and non- hazardous conditions." While it may sound simple, this project is far from it. The complex design required sophisticated elec- trical and control systems, including a motor control system, switchgears, and cabling room. For safety, and to avoid damaging the turbine, the pro- cess design includes sophisticated gas conditioning, cleaning, and dehy- dration to remove impurities such as siloxane, housed inside a robust haz- ardous-rated gas conditioning room. Jensen adds that for an engineer, the entire process was fascinating. "Using biogas as a fuel is interest- ing in its own right. It only contains about half the energy of commercial natural gas. And it comes with a host of impurities, including highly toxic hydrogen sulphide, or H2 S, which requires careful handling." The Power Management System (PMCS) manages power from three systems: the existing reciprocating engines, the new Combustion Turbine Generator (CTG), and the new Steam Turbine Generator (STG). "You have three different power sources all pro- ducing electricity that all have to 'talk' to each other through the power con- trol system," notes McIntosh. The systems within the new expansion are indeed where the true complexities lie. "We've definitely not seen any type of blended compres- sion in the way that we're doing it here. That was a new one for me. We worked with our design team out of U.S. who had quite a bit of steam power experi- ence, but finding biogas specialists was a challenge as this is so new," explains Jensen. However, thanks to team col- laboration, any new challenges faced by the team were overcome. Having started work on the three- year project back in 2019, the team was able to avoid, in part, many procurement issues, but not all. Innovative thinking helped the project move forward, as vendors were switched, the project under- went a number of design reviews and creative thinking was applied. Under normal sequencing, for example, large equipment packages are placed on-site and the build- ing envelope is later constructed around them. However, when delays on certain packages like the steam turbine generator threatened to halt the entire project, Graham decided to leave a large gap in the building's second-floor envelope. Once the pack- age finally arrived, it was craned into position, inserted, and placed inside on its skid mounts, after which the building was enclosed. To succeed with such a technically complex and custom-designed proj- ect required collaboration and open communication every step of the way. "Working with the City of Calgary has been great. They have their operations team for the wastewater plant, and they are wastewater treatment plant operators by trade, yet they've risen to the challenge of learning a completely new process in power generation. They've been very, very excellent to work with," Jensen says. The Bonnybrook Cogeneration Expansion Project has now under- gone commissioning and system operational testing in preparation for handover to the City of Calgary. A LOCATION 4302 15 Street SE, Calgary, Alberta OWNER /DEVELOPER City of Calgary ARCHITECT/STRUCTUR AL /MECHANICAL / ELECTRICAL CONSULTANT Stantec GENER AL CONTR ACTOR Graham Construction TOTAL SIZE 1100 square metres (new lab space); 400 square metres (renovation of existing lab space) TOTAL COST $55.4 million

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