1) The updates generally apply to a change of formatting to two value digits of all typical concentrations for baseflow and stormwater in the database, which have also been transferred to StormTac Web. These changes are generally many but small.
2) In addition to these updates, all new data of baseflow concentrations from additional case studies have been analysed and new mean and median values have been compared with the typical baseflow values per land use. This has resulted in adjustments to the database and StormTac Web. A comparative study has also been done of typical baseflow concentrations between similar land uses, with some adjustments as a result in the database and StormTac Web.
The result of the latter analysis was about 30 adjustments with both reduced and increased typical baseflow concentrations and for default 10 substances in StormTac Web excluding nitrogen (which did not result in adjustments) but also for oil, mercury (Hg) and Indeno(123cd)pyrene (IND) (non-default substances). Typical base flow concentrations from the following land uses were changed:
Mixed green area
Downtown area, less polluted
Industrial area, less polluted
3) During the autumn and winter of 2021-2022, a comprehensive review of all typical stormwater concentrations will be carried out for around 100 land uses and substances. These will be compared with new mean and median values and a plausibility check between similar land uses. This will continuously provide future revised typical stormwater concentrations, including all new case studies that have been added, especially in the past year.