Storm water solutions – best practises and innovation (final report)

Read the full report in Swedish

Summary

The goal of the project was to identify cost-effective measures to reduce the amount of pollutants and eutrophying substances from small stormwater flows in urban areas. Expected results are:

• Two stormwater facilities installed, based on the best available knowledge, which will annually remove an estimated 30 kg of phosphorus, 1 kg of copper, and 130 grams of cadmium.
• A report outlining the current state of new technology for stormwater treatment and the challenges of procuring these within the existing legal framework.
• A workshop on stormwater and new methods to reduce the negative impacts of stormwater pollution on receiving waters.
• New knowledge regarding the selection of sites for stormwater facilities and cost-effective methods for stormwater treatment, facilitating Mälarenergi’s installation of two new stormwater treatment facilities from 2022 to 2026.
• Dissemination of results to public and private companies and municipalities through reports, seminars, and study visits to increase overall knowledge levels.

The overall goal of Measure C9 has been to find the most cost-effective measures to reduce the amount of pollutants and eutrophying substances from small stormwater flows in urban areas. This involves evaluating and identifying stormwater flows containing nutrients and pollutants and then finding suitable locations for measures. The subproject also includes testing and evaluating both best practices and innovative filter technologies.

This knowledge is intended to support landowners and water utilities in their efforts to reduce pollution loads. Additionally, it will contribute to designing various sampling programs and models to ensure cost effectiveness. Measure C9 aims to physically reduce the negative impact of stormwater on Lake Mälaren within Västerås city’s stormwater drainage area.

Project adjustments due to new experiences and changing conditions have resulted in modifications to the project’s scope and content. This report aims to present the results as formulated in the action description after these adjustments:

1. Analysis of stormwater from different areas, viewed from a seasonal
   perspective.
2. Match suitable sites with appropriate technology for medium-sized
   stormwater discharges.
3. Installation, testing, and maintenance of best practice facilities.
4. Evaluation of existing measures constructed by Mälarenergi.
5. Workshop on innovative technologies.
6. Compilation and evaluation of results from Activities 1-5

The following have been completed during the project:

• One stormwater facility has been constructed.
• A year-long sampling of the pipeline network has been conducted.
• A sampling program for stormwater facilities has been implemented.
• A seminar day on stormwater management and a study visit has been
  conducted.
• Attempts to procure innovative stormwater facilities and organize a
  competition to find innovative ways to treat stormwater have been made.
• Investigation and planning for the construction of another stormwater
  facility.

The lessons learned and accumulated knowledge from the project will be used by Mälarenergi in their ongoing work to reduce the amount of pollutants from stormwater into Lake Mälaren. Mälarenergi will continue to disseminate the results and share lessons learned with other municipalities and stakeholders to contribute to cleaner water in our lakes and waterways.