Sustainable Landscape Construction by J. William Thompson & Kim Sorvig

Sustainable Landscape Construction by J. William Thompson & Kim Sorvig

Author:J. William Thompson & Kim Sorvig [Sorvig, Kim]
Language: eng
Format: epub
ISBN: 9781597267847
Publisher: Island Press
Published: 2012-09-11T16:00:00+00:00


Test Modern Hardware for Cleaner Piped Stormwater

Pave-and-pipe stormwater “control” contributes to pollution and is not a recommended practice. Piped systems, however, remain an article of faith among engineers, and many cities, large institutions, and even national parks have legacy systems of stormwater pipes.

Over the past decade, engineering ingenuity has been applied to making stormwater cleaner in the pipe. The engineering solutions, predictably, are mechanical and chemical. As such, they are frequently more costly to install and maintain than the many vegetative and wetland methods described in this book, and appear to fall short of drinking-water-standard output that wetlands achieve.

Nonetheless, faced with existing piped systems or where no other solution is workable or permitted, some of these relatively new devices are worth considering.

Mechanical water-cleaning systems replace or can be inserted into older catch basins or stormwater system components. In general, they are called “stormwater separation or filtration devices.” Using inflow and outflow pipes at different levels, filters, baffles, and vortex flows created by the shape of the device, such in-pipe systems are widely available. According to manufacturers’ claims, they remove oils, fats, suspended solids, nutrients (fertilizers, etc.), metals, and other pollutants. Effectiveness, again according to manufacturers, ranges from 80 percent upward. Even in stormwater trade journals, however, there is debate among engineers as to which devices work best, or even at all.

Chemical treatments for stormwater are also available. Like mechanical systems, these have costs and consequences not found with vegetative and soil filtration.

Related systems for improved septic-tank performance are also available, for example the Pirana and SludgeHammer systems. These may be relevant to constructed wetlands for sewage treatment (below), most of which rely on septic tanks to remove solids.

Landscape professionals concerned with sustainability should be aware of these engineered water-cleansing systems for two reasons. One is as a last resort, where lack of space or budget, regulatory insistence, or heavy-duty pollutants truly require such systems. The second reason to know these systems is to challenge their use on projects where sustainable solutions are more appropriate. A good source of information on these products, as well as for consultant help, is the trade magazine Stormwater.



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