The Stormceptor® MAX was installed upstream of a new dry detention pond, called Ogden Pond, as a stormwater pre-treatment solution. The Stormceptor MAX and dry pond will manage water quality and runoff volume from the 54-hectare redevelopment that discharges into the Bow River. The Stormceptor-to-Pond treatment train will help protect the river from the increased sediment, oil, and stormwater pollution loading from ever-increasing urban growth.
The new development will be a part of the future Green Line Light Rail Transit access. All hardscapes will drain to a dry storm pond but must first be pre-treated with an oil-grit separator (OGS) per the City of Calgary guidelines. Working closely with the City on the design, the Stormceptor MAX 24x24-10 was chosen as the large capacity OGS to capture coarse sediment, with the pond treating finer sediment. This design will significantly reduce the pond's maintenance frequency, and cost as the Stormceptor MAX is much easier and cheaper to maintain.
The project required a large capacity OGS that could meet the water quality objective, bypass the very high peak influent flow rates, capture and store large volumes of sediment, and provide easy maintenance access. The Stormceptor MAX was the clear choice for the engineers and City, while also providing the additional benefits of oil capture and resistance to scour of previously captured sediment during high-intensity storm events.
Imbrium Systems completed the engineering and sizing calculations for the custom parts required for the patented Stormceptor MAX system. At the same time, Lafarge Pipe Calgary designed the Stormceptor MAX's precast layout on the site and coordinated the construction and installation with the engineers and contractors. The sizing of the Stormceptor MAX takes into account the average annual rainfall runoff volume from the project site using PCSWMM for Stormceptor® and ensures the unit meets the City's requirement of capturing 90% of the average runoff volume, removing at least 85% Total Suspended Solids (TSS) of the City of Calgary Particle Size Distribution (PSD), and does not scour out previously captured pollutants.
To help ease future maintenance, the City asked that cleanout spray nozzles be used inside the settling chamber. The time and ingenuity required to design and install the cleaning nozzles in a Stormceptor MAX was the project's biggest challenge. In addition, site conditions produced a high-water elevation in the unit during construction, which necessitated a strategy to divert the dry weather flow with a temporary diversion pipe, thereby allowing nozzle installation.
The quick and successful installation of the Stormceptor MAX required detailed planning and high-level communications between the manufacturer, engineers, developer, contractor, and City of Calgary personnel. The developer, contractor and engineering consultants were all pleased with the outcome of the installation. The ownership of the system and maintenance operations have been handed over to the City of Calgary. The Stormceptor MAX is predicted to capture nearly 60,000 kg of sediment annually.