by Cristian Frers, Senior Environmental Manager and Consultant; Translated by Veronica Wisniewski
We are publishing this article in this edition as an exploration of the alternative treatment methods being employed in other countries around the world. Cristian Frers is a Senior Environmental Manager and Consultant in Argentina where the techniques discussed below are being employed to treat industrial waste water. Thanks to Ecoportal (www.ecoportal.net) and Mr. Frers for allowing us to translate and reprint this article.
Because they require little or no energy to function, constructed wetlands offer distinct advantages over alternative treatment systems. If there is adequate inexpensive land suitable for aquatic conditions and available for the installation of artificial wetlands, such an approach to wastewater treatment can be a cost effective alternative. As an added advantage, such wetlands provide habitat for wildlife.
The importance of wetlands has changed over time. Wetlands serve as transition zones between aquatic and terrestrial environments and provide a dynamic link between the two. Moving along a gradient, water picks up chemicals and sediments which, as they move through the wetland, are transformed and transported to the surrounding landscape.
Wetlands are effective nutrient sinks and absorbers of organic and inorganic pollutants. This absorptive capacity of a natural wetland is the mechanism employed in a constructed wetland for the purpose of treating wastewater from businesses and municipalities. Continue reading
by Julie Whitacre, Fourth Corner Nurseries
Fourth Corner Nurseries offers 74 species of herbaceous wetland plants available as bare-root divisions. These include several species of Carex, Juncus, Scirpus, Aster, Eleocharis palustris, Typha latifolia, Oenanthe sarmentosa, Deschampsia caespitosa, Glyceria grandis, Sparganium, Distichlis spicata, Mimulus guttatus, Potentilla pacifica, Lysichiton americanum, Veronica americana and Stachys cooleyae. Many of these species are available in large quantities (40,000-100,000). These are all grown from seed, not wild collected. Our seedlings often have higher survival rates than wild-collected plants due to less stressful harvesting techniques, and natural wetlands are not impacted. Continue reading
The Vegetation Component
by Julie Whitacre, Fourth Corner Nurseries
As our landscape becomes more developed, management of stormwater runoff is a crucial part of maintaining the health of natural water systems. Diminishing natural streams and wetlands are increasingly important for beleaguered wildlife populations, and we should do all we can to ensure that clean water enters these systems in natural flow patterns. Stormwater runoff often contains high sediment loads and many types of pollutants, including oil and grease, chemicals, pesticides, heavy metals, bacteria, viruses, and oxygen-demanding compounds (Interagency Workgroup on Constructed Wetlands, 2000). Treatment facilities are engineered to capture and transform pollutants in water running off roads, parking lots, and roofs so that they will not reach natural wetlands and other ecologically important habitats. The time over which water from a storm event enters streams can be extended to prevent flooding and, depending on the engineering design and site conditions, groundwater recharge is also possible. Over time, however, pollutants will concentrate in the sediment and vegetation in these facilities, creating an unhealthy environment for aquatic life. Wildlife exclusion devices may be necessary. The loss or damage to wetland habitat incurred during development should be replaced with mitigation wetlands, providing the same functions and harboring the same species diversity and biotic richness as the wetlands they replace. Mitigation wetlands require different designs and may not be used as stormwater filters due to pollution concerns. Continue reading
by Angela Nelson, CESCL
Thanks to Angela Nelson and 2020 Engineering for sharing their expertise on this emerging approach to stormwater management. At the end of the article, we offer a list of plants we believe would be well suited to rain garden plantings based on our experience of field growing them in our sandy loam soil.
What They Are
Raingardens are landscaped depressions designed with specific soil characteristics that are gaining popularity as stormwater filtration and retention devices in lieu of more traditional civil engineering methods. They are a part of a new approach to stormwater management termed Low Impact Development (LID). In low impact development, the landscape component of the project is integral to the stormwater management design, enhances water storage, and attenuates storm flows (Low Impact Development Technical Guidance Manual for the Puget Sound). Rain gardens are aesthetically pleasing, providing beautification to commercial and residential landscaping while at the same time treating and slowing down stormwater flows in a way that mimics natural systems. Continue reading