Prospects and Limitations of Surface Runoff Quality Management in the Republic of Serbia - page 05

 

Experiences in Stormwater Pollution Control and Management

United States

The U.S. has the most advanced measures in the areas of stormwater runoff management and treatment. Nonpoint source pollution control is regulated under the National Pollutant Discharge Elimination System (NPDES) and the implementation of Total Maximum Daily Loads (TMDLs) program to reduce pollutants and improve water quality. This system includes both institutional and technical measures to control nonpoint sources of pollution and stormwater runoff in the form of recommendations and guidelines to be followed in resolving runoff related issues to meet water quality standards assigned to specific sources within the watershed.

There are a number of technical measures that can be applied and tested in practice and they are constantly being improved and modified, depending on site-specific conditions, while at the same time investigations and implementation of innovative approaches are promoted and encouraged. Applied technical solutions are evaluated by competent institutions in regard to treatment performance, cost effectiveness, feasibility, limitations, and other aspects. Results and case studies are made available through publications such as the Stormwater Design Manuals and the Best Management Practice (BMP) Manuals.

The U.S. Department of Transportation, Federal Highway Administration (FHWA) has issued the Stormwater Best Management Practices Manual. The purpose of the manual is to provide guidance for effective stormwater management on roads and adjacent facilities and deal with issues such as first flush volume and other site-specific treatment options. The stormwater discharge quality and treatment options are determined by site conditions and specific pollutant removal goals that the facility is expected to meet in accordance with the NPDES permit requirements. The first flush volume that should be collected and treated may vary and the most frequently used design criteria are the following (U.S. Department of Transportation, 2001):

  • the first 13 mm (1/2 inch) of runoff per hectare (acre) of impervious area;
  • the first 13 mm (1/2 inch) of runoff per hectare (acre) of catchment area;
  • the first 25 mm (1 inch) of runoff per hectare (acre) of the total catchment area.

Generally, the greater the captured and treated volume of stormwater runoff, the greater the reduction of pollution entering the recipients; however, investigations have shown that treating volumes in excess of 25 mm of precipitation per hectare of catchment area will not result in a significant increase of total pollutant removal. Also, recent research shows that collection and treatment of runoff from small, more frequent storms could provide more cost effective solution with acceptable efficiency.

The European Union

Until recently, the European Union had no unified approach to solving the problem of stormwater runoff. Similarly, as in the U.S., a series of technical measures were applied and tested in practice. Applied technical measures are evaluated by competent institutions from the perspective of the achieved results and these findings are published in the form of manuals and guidelines for Best Management Practices (BMP), while in the United Kingdom these techniques are summarised under the Sustainable Urban Drainage Systems (SUDS). Applied techniques, design criteria and the effectiveness of treatments vary greatly from country to country.

In 2000, the European Union introduced a radical change in the approach to water management by adopting the Water Framework Directive (WFD) that introduces the river basin approach as a way to manage water resources. The year 2009 was the deadline for Member States to draw up River Basin Management Plans (RBMPs) and programmes of measures to meet the WFD's objectives with the aim of achieving "good ecological and chemical status" of all surface waters in the EU by 2015, which includes the following:

  • Protection of the aquatic ecosystems and prevention of further deterioration;
  • Promoting sustainable use of water resources;
  • Improvement of water resources and aquatic ecosystems;
  • Progressive reduction and prevention of pollution of groundwater;
  • Contributing to mitigating the effects of floods and droughts.

The negative effects of runoff from urban areas are clearly identified in the WFD through the term "heavily modified water bodies" and demands for implementation of pollution prevention and control measures for diffuse pollution sources in order to achieve the water status objectives. Therefore, urban runoff management will be one of the key elements of the WFD integrated and innovative approaches to water management. At this point, some program measures are still in the implementation stage but it is expected that measures will vary from location to location, depending on basin-specific requirements.