R.W. Tomlinson removed and replaced the old storm sewer system draining as part of the Ottawa Airport “Passenger Terminal Building Expansion — Phase II Terminal Apron Works” contract. The new system allows drainage of the new apron surface. It was designed by Ainley Engineering/Earth Tech.

The objective of this project was to supply storm water management, and to create a system that can handle or contain a fuel spill of up to 30,000 liters of jet fuel, preventing any contamination to the municipal storm sewers, streams and rivers. The storm sewer draining the apron areas was designed to capture a 10-year return storm event. The equipment chosen to meet the design needs was the Armtec Vortech Oil Grit Separator. The Vortech system is a hydrodynamic separator that enhances gravity separation of target pollutants from storm water.

A broad-crest weir installed upstream of the Vortech will control the runoff so that the flows from a 10-year (or less) return storm event will be directed to the Vortech for treatment. The larger flows will overflow directly into another leg of the storm sewer without treatment. Beyond capturing the debris and silt from the first flush rain event, the Vortech was designed to capture a spill up to 30,000 liters of jet fuel. In response to concerns about the downstream water course, the design incorporated two mechanical gates to close the storm sewer outlet in case of a major spill. These two motorized gates can be operated manually or from a remote emergency panic switch installed at the gates.

The Vortech unit arrived on the project site in five precast sections, with a total weight of 26,900 kg. Although installation of the unit was a two-day project, the actual assembly took less than eight hours. The advanced planning made the project go smoothly.