Before the perimeter access road (PAR) surrounding the Canadian Port of Entry (POE) can be built, a stormwater management system designed to collect rain run-off from the road will first need to be installed. The PAR stormwater management system is comprised of approximately four kilometres of culverts, two settling tanks known as oil and grit separators, two stormwater management ponds, and the Broadway Drain.
The oil and grit separators (OGS) improve the quality of water being released into municipal drains by capturing debris and sediment and trapping hydrocarbons and oils which may be present in stormwater runoff.
Two “swirl” type OGSs are being installed at the Canadian POE as they are proven to be most effective in treating large volumes of stormwater runoff which could accumulate on paved areas such as roadways. Each concrete, pre-fabricated OGS weighs approximately 405 kilograms and are buried along the PAR right-of-way.
Stormwater run-off from the PAR first enters storm sewers through culverts. The stormwater then travels to the OGS through an inlet pipe. The swirling motion of the water within the separator promotes gravitational separation of solids which settle on the chamber floor. The stormwater then exits the swirl chamber where a screen traps debris, sediment and hydrocarbons and then travels through pipes to one of two stormwater management ponds. The treated stormwater eventually flows into a municipal drain.
The OGS will be inspected regularly and cleaned by a vacuum truck to remove accumulated sediment and oil. The collected material is then sent for appropriate disposal.