Updated StormTac database v. 2018-05-09
Relase notes v18.2.1
– Included area names in the scroll list when selecting area (A1, A2, etc.) in the flow chart.
– The box “Retention basin” has been made clearer regarding which parameters can be used for different selection of facilities. Those who do not belong to the selected facility are highlighted in blue in the input fields and can not be changed.
– The box “Biofilter”. In the header at the top left is now showing what facility is selected. After saving your changes, you can see which type of facility it is instead of having to go to the flow chart and look at the facility picture below the box.
The facilities grass ditch / swale are explained as separate facilities. These are now also shown individually in the facility picture below the box.
– Some minor bug fixes have been made.
– Small design and layout changes have been made.
Updated function for natural ground for smaller areas than 10 hectares
For areas less than 20 hectares, the maximum flow at a 5-year rain corresponds to 40 l/s/ha (P110, Swedish Water, 2016), whereby the equation has been adapted to this, resulting in smaller flow than previous in smaller areas than 10 hectares. However, the same equation as earlier is valid for areas > 10 ha.
Updated concentrations for phosphorus, nitrogen and benzo(a)pyrene from woodland, farmland and other open land uses
Results of a comprehensive literature study and comparison between different references and measurement data. The update is particularly important in calculating load before exploiting an area and if the load should not increase after exploitation. The concentration data have been reduced for phosphorus and nitrogen but increased from zero to small levels for benzo(a)pyrene. This applies to both concentrations of stormwater and baseflow, with total calculated phosphorus and nitrogen concentrations being lowered more for woodland and farmland than the standard stormwater concentrations. Reference data is shown in blue text in the database from 2018-03-11 and implemented for new projects that start after 2018-03-11.
Updated database v. 2018-02-26
New data of zinc surfaces and copper surfaces, e.g. copper facades or roofs, zinc rails or roofs, which can be calculated in StormTac Web by using the land use “Own”, see Guide Description of land uses 2018-02-26.
Updated flow detention functions in serial facilities
Updated and revised functions have been developed for calculating required volumes for flow detention in serial facilities. These take into account factors for flow reduction in both previous and subsequent facilities.
The revisions affect both existing and new projects but do not make any changes in individual facilities and the first facility in a series of facilities.
They provide relatively small changes in subsequent facilities if the flow is not reduced as much between the facilities, but major changes if large flow is passed (no or less throttle) with greater flow detention downstream.
The functions take into consideration that, as before, the flow from the previous facility reduces the outflow up to some longer rainfall duration, after which all lower flows flow further downstream.
If long duration will be dimensioning downstream and there is strong flow reduction downstream, this may result in the upstream facility, in some cases, not will be as effective as you might think for reducing the required detention volume downstream.
This because a flow below the reduced flow could be dimensioning for long duration.
Then you can try to increase the flow reduction factor, which results in shorter design rain duration and reduces the required detention volume.
In practice, this means that you use a flow regulator in the outlet.
All this can now be simulated better than before by using the updated and revised functions.
Local, regional or country specific precipitation and rain intensities
Implementation of license customized yearly precipitation and rain intensities in Settings, so the user can start each new project with local, regional or country specific data.
Implementation of a method for calculation of rain intensities from regional input data from optional location in the World, by iteration of a regression coefficient.
Implementation of two new treatment facilities; dry ponds and sedimentation screen basins & revised coefficients for calculated reduction efficiency of the facilities biofilters, macadam ditches, swales and ditches
Dry ponds (ponds without permanent pool, with bottom outlet and dry between rain events) have been added as a new treatment facility in the biofilter box. Before, dry pond could only be designed for flow detention in the box Flow detention facility, or be designed as e.g. swales in the biofilter box. Now they can be designed for both treatment ad flow detention in the biofilter box.
Sedimentation basins (screens in ponds/wetlands or in the recipient water body) can now be designed in the wet pond box.
Descriptions appear in this box and in the box Reduction efficiency.
It is important to consider the lengt:width relation and that no extra effect for flow detention should be accounted for when calculating the reduction efficiency for screens in recipients, but else the design is the same as for wet ponds and wetlands.
Revised coefficients for calculated reduction efficiency of the following facilities and substances have been made after comparative studies of the data, and since more data have been added to the data base:
Biofilters: Pb, Cd, Cr, Ni, oil, PCP.
Macadam ditches: SS.
Swales: P, N, Pb, Cu, COD.
Ditches: P, Cu, Zn, Ni, SS, BOD.
This means that the calculated reduction efficiencies will be changed for the above facilities and substances for projects started after this release date.
2 added land use categories; marina and artificial turf fields
The two new land uses (small boat) marina and Artificial turf field have been added to the application and the data base, with standard concentrations for stormwater and baseflow respectively. The guide with description of land uses has been updated accordingly.
Complementary results at the bypass of peak flows past the treatment facility
In cases where flow detention is not in focus and the flows into the treatment facility are deemed to be too strong, it may be appropriate to bypass the peak flows past the treatment facility.
This update provides additional information in case of bypass.
In the flowchart and the results reports, are now not only the treatment effect, concentration and load of total transport presented, but also the treatment effect of the treatment plant itself, which concentration and load that flows into and out of the facility, respectively.