|Environmental Sensitive Design|
With the advent of LID, ESD and other environmentally friendly design guidelines and increasing construction of green buildings, these standards are requiring innovative methods of handling stormwater from developed areas. Essentially, ESD combines conservation practices with distributed storm water source controls and pollution prevention to maintain or restore watershed functions. These controls include, but are not limited to: onsite stormwater management systems (rain gardens and bioswales),
pocket wetland systems, other methods that infiltrate water to the soil and restorative systems such as Regenerative Stormwater Conveyance (RSC) systems.
BlueWing now has the capability to design and build the rain gardens, bioswales and RSC systems mentioned above.
Rain Gardens – also called Bio-swales
Rain gardens are simply low-lying, vegetated depressions--generally 3 to 6 inches deep--which have absorbent soils that temporarily collect stormwater runoff from impervious surfaces and allow the runoff to slowly percolate into the soil. The depression should be a flat-bottom, saucer shape rather than a bowl shape so that rainwater runoff can sheet out throughout the garden to allow for better infiltration. This generally takes a few hours and shouldn't take more than two days. Rain gardens are attractive landscaping features that function like a natural moist garden, moist meadow, or light forest ecosystem. They can look as informal or as formal as you like. While rain garden dimensions vary, remember, any size rain garden is better than no rain garden.
Rain gardens provide flood control, groundwater recharge, and water-cooling benefits, while the plants, soils, and associated microorganisms remove many types of pollutants—such as excess nutrients, pesticides, oils, metals, and other contaminants—from stormwater runoff. Stormwater pouring off hot roofs, pavement, and other impervious surfaces is temporarily captured, cooled, and allowed to percolate into the ground. Nutrients such as nitrogen and phosphorus, which would otherwise contribute to algae blooms and other problems in the Bay, are instead put to beneficial use by being taken up by the plants in the garden. Some studies show that about 50 percent of such pollution comes from individuals and homeowners, through yard care, yard waste, and chemical pollution from household activities.
Past stormwater management practices including piping and stormwater management facilities have actually solved one problem (stormwater management and handling from developed areas) and have caused another, severely eroding streams pouring sediment into the tributary waters and eventually the Bay itself. The innovators of the RSC technology, Keith Underwood has come up with a better way to handle and manage stormwater from developed areas. Basically, RSC ‘s are giant sand filters (not unlike our Floating Treatment Wetlands) that rely on pore space and biological activity to filter and clean the waters that come in contact with them. For example, an eroding stream channel and failed concrete headwall and pipe system, caused by rapidly flowing stormwater can be restored using this technology.
How do RSC’s work?
The systems rely on all natural materials: sand, mulch, gravel, cobbles and large boulders, laid into the eroding stream channel. These materials are arranged in a series of step pools designed with large boulders at the wiers and with sand/mulch filters in the bottoms. Each step down into the next pool provides another opportunity for additional biological filtering and cooling of the stormwater flows.