July 21, 2005
"We do the water first"
"We do the water first." That is how the renowned German stormwater designer, Herbert Dreiseitl summarizes his approach to stormwater management. Speaking at the 12th conference of the Congress for the New Urbanism in Chicago in June 2004, Mr. Dreiseitl illustrated his unique blend of art and engineering in settings both urban and suburban. His experience in complying with long-standing European requirements that runoff be reduced or eliminated provided a useful confirmation to his American audience that it is not only possible to preserve pre-development hydrology, but that compliance can be interesting and beautiful.
EPA’s Phase II program is being implemented by the states to cover sites as small as one acre, requiring that post-development runoff be controlled for most of the rain storms that occur in an average year. This change of emphasis – from controlling peak flow rate to controlling runoff volume – is probably the most significant change in water management requirements for land developments in the past thirty years. Gradually, as the states develop their programs, local governments will have to incorporate the new stormwater management requirements into their development rules. During this transition period, which will probably last for a year or more, site designers will have to meet both the evolving state requirements and the existing local regulations, resolving the inevitable conflicts by thoughtful application of hydrologic principles.
Stormwater management concepts should be sketched out at the earliest stage of site planning to allow the natural site hydrologic features to function as much as possible on the developed project. This approach is a significant change from thirty years of civil / site design practice, which dealt with getting the water off the site with inlets and pipes.
To see some of the imaginative projects designed by Atelier Dreiseitl, visit http://www.dreiseitl.com
Posted by aquacura.com at 07:57 PM | Comments (0)
July 13, 2005
Chlorinated water and vegetation
I am managing a project for the Paxton Creek Watershed and Education Association that will entail retrofitting bioretention into a pair of stormwater detention ponds at a township-owned recreational facility. One of the ponds receives regular flows of highly chlorinated water (say 3 to 5 ppm chlorine) weekly when the whirlpool bath is emptied. The effect of this water seems to be evidenced by a "shoreline" below which no vegetation survives. The pond is planted in turf grass.
The other pond, which receives roof and parking lot runoff, has fairly healthy turf and a pretty nice stand of emergents in the low area, so the whirlpool discharge would seem to be the culprit.
Here's the question: can someone recommend vegetation that would stand up to the chlorine? We cannot ask the township to modify its practices, so we have to find a way to live with the discharge.
Posted by aquacura.com at 09:46 AM | Comments (4)