Control of Urban Runoff Pollution

Some of the traditional ways of controlling urban runoff are installing storage tanks, settling tanks and retention ponds. In order to use these methods effectively, the area that needs to be controlled has to have the right slope, and other conditions. Another problem with these methods is that they are not aesthetically pleasing to many people. These methods can also get to be very expensive to maintain. The latest in urban runoff control is a device called Stormceptor. Stormceptor is installed underground and collects runoff and treats it.

The Stormceptor is a simple but revolutionary patented stormwater quality treatment device that efficiently removes oil and suspended solids. The Stormceptor is divided into a lower storage/separation chamber and an upper by-pass chamber.

Normal flows are diverted into the lower treatment chamber where oil and other liquids with a specific gravity less than water rise and become trapped and suspended solids settle to the bottom of the chamber by gravity and centrifugal forces. During high flow conditions, the by-pass chamber conveys water to the downstream sewer directly circumventing the lower chamber and preventing the resuspension and scour of settled pollutants.

Maintenance is one of the biggest issues when deciding which control device to use. The Stormceptor was designed to be easily monitored and cleaned from the surface without requiring entry into the unit. Maintenance is performed from one access point by vacuum truck.

In order to tell whether ithe Stormceptor needs to be cleaned, an inspector will come to the site and measure the amount of sediment in the tank. Since this can be done by just opening the top of the Stormceptor up, and measuring with a stick, this only takes about 20 minutes. If the Stormceptor needs to be cleaned, a vacuum truck will come and take out all of the sediment. The time in between each cleaning depends on where the Stormceptor is. The cost of cleaning also varies depending on the size, but in most cases it is cheaper and as efficient in controlling runoff as the traditional devices.
Since the Stormceptor is a new technology, there have been many tests done on it. One of the field monitoring tests was done in the city of Edmonton. The city installed three Stormceptors, and they used them to pretreat inflow into existing stormwater ponds. During the monitoring period there was an oil spill, and the Stormceptor captured all of the oil. The monitoring in the city of Edmonton was bas based on flow proportional water quality sampling at both the inlet and the outlet from the Stormceptor. Four storms were sampled in 1996, and below are the removal rates.

The Stormceptor is new and the maintenance is relatively cheap. From the studies done it seems to work best as a pretreatment before entering ponds. The company that manufactures them hopes to improve them in the near future.

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