Survey of the Operational Status of 25 Swedish Municipal Stormwater Management Ponds
Number of Authors: 6
2017 (English)In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870Article in journal (Refereed) Epub ahead of print
During the past 50 years, wet stormwater ponds have been constructed to reduce negative environmental impacts of urban stormwater discharges on receiving aquatic environments. However, in many jurisdictions there is little informationon the current operational status of such ponds and their functioning. This paucity of information prompted a field survey of 25 Swedish municipal stormwater ponds, aged between 3 and 26 years. The pond survey focused on estimating the pond hydraulic loading and efficiency, the state of littoral vegetation, characteristics of bottom sediment in the inlet and outlet zones (sizes and the chemistry), and the overall operational pond status, including the access for maintenance. The hydraulic efficiencies of ponds were estimated for pond footprint shapes and relative locations of the inlets and outlets using literature data. The estimated hydraulic efficiencies correlated well with the pond length-to-width ratios and the ratio of the pond surface area to the impervious area of the runoff contributing catchment (i.e., the hydraulic loading). Littoral vegetation was inspected visually and found to be overgrown at some facilities, which impeded the maintenance access. Benthic sediments in ponds contained silt and clay (<63 μm <63 μm ), sand and gravel fractions, and when compared with the literature data, such sediments appeared relatively coarse. Chemical characteristics of sediments reflected anthropogenic (traffic) activities, but without excessive contamination warranting special disposal requirements. Of the 25 ponds surveyed, four were fenced off and inaccessible to machinery. In fact, the design of these four ponds was such that it made inspection and maintenance very difficult, which may pose potential risks to ponds operation. Fifty-four percent of the investigated ponds were in need of minor maintenance, primarily because of sediment and litter accumulation in their inflow and outflow sections. The fact that the inspection survey revealed relatively few minor issues that could be corrected easily demonstrates the importance of relatively simple regular inspections serving to detect minor problems at an early stage before they would seriously impact pond functioning. The above survey methodology should be helpful for developing similar low-cost surveys in other jurisdictions.
Place, publisher, year, edition, pages
Research subject Urban Water Engineering
IdentifiersURN: urn:nbn:se:ltu:diva-61982DOI: 10.1061/(ASCE)EE.1943-7870.0001203OAI: oai:DiVA.org:ltu-61982DiVA: diva2:1074015