Technologies in Storm Water Management: Green Technology Articles: Eco20/20

Technologies in Storm Water Management

Storm water picks up pollutants, wastes, sediments, and heavy metals, and carries them into the environment. Eco-friendly developers prepare for run-off on their sites by planning for and employing non-structural storm water controls, such as filter strips and grass swales, and structural management devices. Here's what to look for if you're seeking an eco-friendly development.

Green Site Planning

The best approach to managing storm water is to begin where it starts.

* Impervious surfaces should be minimized and natural buffers and depressions for drainage should be preserved; which means building as few roads as possible, fitting the development to the terrain by using building clusters, and leaving more open spaces compared to intensive developments.

* Where watersheds can't be preserved, they should be mimicked. Avoiding curbs and storm drains will prevent excessive runoff.

* Storm waters should be collected separately from waste waters and used locally to water plants.

Non-structural Technology

Swales, filter strips and filter drains should be used as roadway verges and around car parks. Basins or ponds are another important part of an eco-friendly design.

* Swales are long channels, created by digging a ditch along a contour and piling the dirt on the downhill side. Filter strips are sloping areas of ground. Both allow run-off to flow through vegetation, which slows and filters the flow. The vegetation captures nutrients and helps remove sediments from the water. Local grasses and flower species may be used for visual effect and to provide a wildlife habitat. Regular mowing, litter removal, and removal of excess silt are necessary.

* Filter drains are materials layered under grass, gravel, or permeable blocks to encourage storm water to drain through. The material of the drain will trap sediment and filter the water. The surfaces should be kept clear of silt and weeds and cleaned regularly.

* Whether artificial or natural, basins and ponds will slow the flow of water during a storm. Both can be vegetated for recreation or wildlife. Run-off water quality is improved by basins and ponds through sedimentation of solids, bacterial action and nutrient uptake by vegetation. Water stored in ponds can also be used for irrigation of parks and gardens, for groundwater recharge, or for fire-fighting.

Structural Technology

An eco-friendly development will also employ structural controls to remove pollutants and pathogens from storm water.

* Residents will be allowed, even encouraged, to handle storm water at the household level, as roof run-off kept in a tank for irrigation of a garden or trees.

* Catch basin inserts are devices that capture sediment, debris and tiny particle pollutants. Organic screen, synthetic screen, or vortex type separators are some of the inserts a developer might use to address issues such as oil, grease, suspended sediment, total solids, zinc, copper, and lead, as well as organic contaminants such as salt, fecal matter, nitrates, phosphorus, and hydrocarbons.

All ecologically sound storm water management technologies, whether physical, chemical or biological, are akin to the purification and recycling processes taking place in nature. When buying a home, look for the features that will indicate what attitude the developers have taken toward storm water management.