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Assessment of Existing Roadside Swales with Engineered Filter Soil: I. Characterization and Lifetime Expectancy
Author(s) -
Ingvertsen Simon T.,
Cederkvist Karin,
Régent Yoann,
Sommer Harald,
Magid Jakob,
Jensen Marina B.
Publication year - 2012
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2011.0318
Subject(s) - swale , infiltration (hvac) , environmental science , surface runoff , stormwater , soil water , hydrology (agriculture) , environmental engineering , soil science , geotechnical engineering , geology , geography , ecology , meteorology , biology
Roadside infiltration swales with well‐defined soil mixtures (filter soil) for the enhancement of both infiltration and treatment of stormwater runoff from roads and parking areas have been common practice in Germany for approximately two decades. Although the systems have proven hydraulically effective, their treatment efficiency and thus lifetime expectancies are not sufficiently documented. The lack of documentation restricts the implementation of new such systems in Germany as well as other countries. This study provides an assessment of eight roadside infiltration swales with filter soil from different locations in Germany that have been operational for 6 to16 yr. The swales were assessed with respect to visual appearance, infiltration rate, soil pH, and soil texture, as well as soil concentration of organic matter, heavy metals (Cd, Cr, Cu, Pb, Zn), and phosphorus. Visually, the swales appeared highly variable with respect to soil color and textural layering as well as composition of plants and soil‐dwelling organisms. Three swales still comply with the German design criteria for infiltration rate (10 −5 m/s), while the remaining swales have lower, yet acceptable, infiltration rates around 10 −6 m/s. Six of the eight studied soils have heavy metal concentrations exceeding the limit value for unpolluted soil. Provided that the systems are able to continuously retain existing and incoming pollutants, our analysis indicates that the soils can remain operational for another 13 to 136 yr if the German limit values for unrestricted usage in open construction works are applied. However, no official guidelines exist for acceptable soil quality in existing infiltration facilities.