INNOVATION November-December 2015

f ea t ures

Photos: Opus DaytonKnight

Harvest Energy Garden mimics organic decomposition in landfills. The percolator where waste is hydrolyzed and acidified, and the soluble organics are recirculated (recirculation pump system, left), the buffer tanks and digester tank (right) provide environments where anaerobic microbes break down the waste and release methane.

“We needed to surround GICON with local firms who could understand and interpret GICON design and put it into the format of construction-ready drawings and specifications,” says Kumar. “It takes a big team to introduce a new technology.” The team included Pottinger Geharty Limited, which handled the Environmental Assessment, First Nations consulting, air emissions permit, and subsurface methane investigation. LMDG Building Code Consultants reviewed and interpreted the Life Safety and Fire Protection codes review and interpretation. Thurber Engineering acted as the geotechnical engineer on the project, ISL Engineering as the site civil engineer, and CH2M Hill provided the value engineering. DA Architects created the architectural design of the visitors’ centre and served as architectural consultants for the biogas energy plant. Maple Reinders Inc. functioned as the construction manager and general contractor, and Weiler Smith Bowers Consulting Structural Engineers served as the project's structural engineers. “The whole structure is made up of various components, so there’s not one typical construction scheme in the building,” says Kevin Lemieux, P.Eng., Struct.Eng., a Principal of Weiler Smith Bowers. “The green energy centre is a typical two-storey office building. There’s also a receiving hall and the percolator structure where they let the waste compost. There are service rooms, mechanical rooms, underground trenching tanks, and there are some large steel tanks and concrete holding tanks outdoors, as well. The percolator structure had to be carefully designed, because there’s the requirement for it to be gas-tight.” Lemieux says the project’s components and complexity meant five types of concrete were required. “There were many discussions back and forth with the concrete experts to come up with a high-performance concrete specification.”

and all are variations on the same theme of how the material is digested anaerobically. GICON, says Kumar, had an innovative process that “allows green waste and food waste to be digested simultaneously, with no prerequisite for contamination removals.” Process At Harvest Energy Garden, yard and food waste is tipped into a receiving hall for processing prior to being fed into the anaerobic digestion process. The food waste is shredded to break open bags, boxes and other containers. Plastic bags, boxes and large contaminants are removed, and the remaining material is blended and stockpiled for placement into large percolators. Each of the 10 percolation tunnels is thirty metres long, four metres wide, and five metres high. Percolation prepares the materials for rapid digestion at the next stage. The organic material is hydrolyzed and acidified to produce volatile fatty acids. Kumar says, “The hydrolyzed and acidified materials become soluble and are washed out with the percolate. These soluble organics are collected and recirculated for two weeks. Part of this percolate is stored in a hydrolysate buffer tank. In Stage Two, this percolate is further anaerobically digested in a fixed-film digester tank by methane-forming organisms. Most of the biogas is produced in this stage.” Planning and Building Opus DaytonKnight worked with GICON to adapt the mechanical and electrical design, and was the main sub-consultant to GICON on the process as the design was developed and translated from European standards. GICON was the lead designer and did the process engineering. The German-based HERMOS provided the instrumentation and control and electrical engineering.

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