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This article in JEQ

  1. Vol. 41 No. 6, p. 1960-1969
    Received: Sept 6, 2011
    Published: November 5, 2012

    * Corresponding author(s): sti@life.ku.dk


Assessment of Existing Roadside Swales with Engineered Filter Soil: I. Characterization and Lifetime Expectancy

  1. Simon T. Ingvertsen *a,
  2. Karin Cederkvistc,
  3. Yoann Régentab,
  4. Harald Sommerd,
  5. Jakob Magida and
  6. Marina B. Jensene
  1. a Dep. of Agriculture and Ecology, Faculty of Life Sciences, Univ. of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
    c Dep. of Basic Sciences, Faculty of Life Sciences, Univ. of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
    b current address: Sustainability, Vestas, Smed Hansens Vej 9, 6940 Lem, Denmark
    d Ingenieurgesellschaft Prof. Dr. Sieker mbH, Rennbahnallee 109A, 15366 Hoppegarten, Germany
    e Center for Forest and Landscape, Faculty of Life Sciences, Univ. of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg C, Denmark. Assigned to Associate Editor C.A. Grant


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.

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Copyright © 2012. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.