By Robert Y.G. Andoh

Throughout the world, thousands of stormwater pollutant removal systems are being installed in an effort to prevent watercourses from being polluted. As supply has risen to meet demand, a variety of proprietary, chamber-based systems have emerged, including hydrodynamic separators, which are designed to settle out and store sediments and associated pollutants, preventing them from being discharged to the natural environment.

However, recent research suggests that some systems may not be as effective as might be claimed. Some systems are subject to “washout” or “scour,” whereby captured and stored pollutants are flushed from a system during extreme wet weather.

By Robert Y.G. Andoh, Mike Faram and Dave Scott

Water industry officials throughout Europe – and in a growing number of municipalities in North America – tend to think of vortex valves as a novel technology for outlet flow control on a stormwater detention system. Most of these 17,000+ valves installed around the world are, in fact, implemented on stormwater detention schemes because use of a valve can reduce the required storage volume by up to 50% while still meeting the maximum discharge requirement. But vortex valves actually have many other uses in stormwater, wastewater and combined sewer systems. These versatile devices tackle a number of other problems, including erosion control, re-oxygenation of water and flow equalization in wastewater treatment plants.