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Ecological Sustainability and Urban Green Space |
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Urban Density
and Green Structure Case Studies Ringkøbing
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MANAGEMENT OF WATER FLOWS |
RINGKØBING CASE STUDY - MANAGEMENT OF WATER FLOWS
Joern Morthorst, geologist , Geological Survey (GEUS)
Urban areas: The Municipality of Ringkøbing gives high priority to renovation of worn down sewer systems, especially waste water pipes. They may cause serious pollution of fresh groundwater. At a high groundwater pressure outside the pipes, groundwater may result in an additional load on treatment plants in areas with combined, as well as individual, sewer systems.
Sewer overflows, detention basins and stormwater basins should be managed by using SOCOMA techniques. In this way overflows of polluted water from the combined sewers, as well as less polluted surface water from the individual sewer areas, would be "purified" before it is led to a recipient. This is not done today. Apart from the purification effect, the above types of basins might be used for recreational purposes, and not necessarily be combined with any significant infiltration (groundwater development), as this will not be needed in the Ringkøbing area for supplementing the existing abundant groundwater resources for catchment.
Part of the stormwater run off from paved areas in Ringkøbing is discharged directly into the inlet. This practice ought to be substituted by SOCOMA facilities. A few existing detention basins ought to be converted into or be replaced by SOCOMA facilities. Stormwater should optimally pass an oil separator before being discharged into the different types of basins and treatment plants, as stormwater from paved areas with traffic loads often contains oil and gas residue.
In new residential developments it ought to be a requirement that less polluted water from paved areas is drained via oil separators to SOCOMA facilities and thereby infiltrated. Draining the stormwater run off to a recipient in the neighbourhood is another possibility already used in a few cases. Establishing only one pipe. i.e. for transporting waste water to the treatment plant and avoiding pipes for stormwater makes it possible to establish SOCOMA facilities at no extra cost.
Rural areas: The water quality of recipients is also influenced by waste water treatment in rural areas. There is currently little or no quality control of the rural waste water.
A municipal regulation about waste water treatment is on its way, including a description of water quality acceptable before discharge into local recipients. This will be supported by a general, national regulation expected to require treatment of rural waste water by a root zone facility.
Geology: Geological and hydro-geological conditions in the municipality show that surface soil strata consist mainly of postglacial aeolian sand, meltwater sand and gravel with a few inclusions of freshwater peat and clay till. Conclusions: Urban waste water treatment in the Municipality of Ringkoebing seems to be up-to-date (apart from leaky sewer pipes) and norms laid down in the national "Water Environment Plan" are closely adhered to. However, sewer treatment in rural areas still leaves much to be desired.
Current stormwater treatment could be improved in urban areas, however, as most of this is still led directly to a recipient without any form for treatment (oil seperator, SOCOMA facility).
The impression today is that Municipality of Ringkoebing has serious intentions of solving the problems of leaky sewer pipes and treatment of sewage and surface water prior to discharge to a recipient. However, more rigid control is needed and a higher priority must be given to environmentally sound water management in the new and existing urban areas. In this way it will be possible in addition to support both nature and recreational opportunities.
The capacity for establishing SOCOMA facilities is present almost everywhere in the municipality, as is the local infiltration of stormwater. The most suitable type of facility depends on the local situation. On the establishment of infiltration facilities, the risk of bacteriological pollution of existing and future groundwater catchment must be considered, in particular where infiltration plants are located in relation to the catchment area. This is especially true for shallow borings with screens close to the surface, which is typical of rural areas, while deeper catchment borings for larger supplies are generally covered by a layer of clay of varying thickness and consequenly are not so sensitive.
In connection with all infiltration and water catchment it is important to pay close attention to the location of any possible known or potential pollution sources. Click here to return to the top of this page and to access menus |
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