18th of March, at the conference VAK2020 Jönköping

18th of March, at the conference VAK2020 Jönköping

Come and meet four of us, on the 18th of March, at the conference VAK2020 (Vatten avlopp kretslopp) in Jönköping, Sweden. There you get the opportunity to ask us questions about StormTac Web and see us show the application live. We will be in Monter 35. Hope to see you there!

/StormTac Team

Updated land-use specific runoff coefficients per land use

Updated land-use specific runoff coefficients per land use

The volume runoff coefficients and the design runoff coefficients have been investigated through supplementary literature studies and compared, after which revisions of the typical template values ​​and interval values ​​have been performed for some land uses. These changed runoff coefficients have also been compiled in the database.

These adjustments refer to typical recommended values, but both of these types of runoff coefficients can still be changed according to site-specific conditions. This e.g. applies to the land use Forest with increased typical runoff coefficients that have been adjusted after extensive empirical studies in Sweden and the US, but which also show large variations between different locations. More about this can be read in a new section in the Guide, under Design Flow.

In the same chapter there is also news from an international study which indicates that there is no significant relationship between the runoff coefficient and the size of the catchment area, which also means that there is no upper value for the catchment area for employing the rational method in the model, so it can be used without a specific upper limit area, provided that site-specific conditions such as longest runoff transport (concentration) time are carefully considered.

Updated typical concentrations for stormwater and baseflow from road…

Updated typical concentrations for stormwater and baseflow from road areas

Updated (reduced) typical concentrations for stormwater for Hg from the following land uses:

– Office area
– Residential area without road ditches, min
– Residential area without road ditches, max
– Multifamily area with street trees in a skeletal soil (macadam-soil mixture) without Local disposal of stormwater in the block
– Multifamily area with street trees in a skeletal soil (macadam-soil mixture) with Local disposal of stormwater in the block
– Multifamily area with biofilter without local disposal in block
– Multifamily area with biofilter with local disposal in block
– Office area with street trees in a skeletal soil (macadam-soil mixture) without Local disposal of stormwater in the block
– Yard area within block
– Artificial turf field

Updated typcical concentrations regarding all substances and the land uses:
– Local street with curbstones
– Local street after reduction in open ditch.

Updated (reduced) baseflow concentrations from road areas for the following substances:
– N, Zn and Cr.

Updated yearly precipitation data (box Precipitation)

Updated yearly precipitation data (box Precipitation)

In the Precipitation box, there are now examples of only selected sites corrected yearly precipitation, however more data on both corrected and uncorrected precipitation incl. references are compiled in the Guide

Scenarios have been implemented to the Recipient model (box…

Scenarios have been implemented to the Recipient model (box Watershed area and box Recipient data)

Different scenarios
Below the box Watershed area, a new Scenario can be added. By adding a new scenario, it is
possible to simulate how the recipient is affected by changes within the watershed area (for
example after an exploitation) or in the recipient (for example, increased volume after dredging).
In Scenario 1, measured concentrations in the recipient can be specified. If
measurements are stated in Scenario 1, a corrected total concentration will be calculated for the
other scenarios. The corrected calculated total content (C,rec,corr) takes into account any over- or
underestimation of the calculated recipient concentration compared with stated measurements in
Scenario 1.

Updated concentration data from recycling center, and data of…

Updated concentration data from recycling center, and data of impregnated and untreated wood

1. Updated concentration data from recycling center

All substances have been updated after extensive flow proportional sampling of stormwater from three Swedish recycling centers. The assignment was carried out by Sweco in 2019 on behalf of Avfall Sverige. The volume-weighted samples have been calculated by StormTac.

2. Data of impregnated and untreated wood

A literature study was conducted whereby 5 case studies were found with data on stormwater runoff from impregnated and untreated wood surfaces, respectively. This data is entered in the database under Other surfaces and can be calculated in StormTac Web by selecting the land use Own and entering the values ​​manually, but data is missing for some substances and only a few data have been found for base flow, so assumptions can be made in the model regarding these. Once more data has been found or estimated, impregnated and untreated wood can be selected for land use in StormTac Web.

Updated concentrations for stormwater and base flow

Updated concentrations for stormwater and base flow

Updated stormwater concentrations for all substances for the following land use:
Block without road with local disposal of stormwater

Updated stormwater concentrations for AAe, FLUO and NAP for the following land use:
Block without road

Updated stormwater concentrations for all land uses for:
4-tert-OP

Updated base flow concentrations for all land uses for:
Alachl
ANT
As
Atraz
Benz
BDE47
BDE99

Complemented recipient model with calculation of point loads from…

Complemented recipient model with calculation of point loads from concentrations and from sea to bays

If you do not have input data on the point load in the unit kg/year but instead as a concentration (µg/l) you can specify the concentrations and get the calculated point load. Point load from sea to sea bay can be calculated in different ways depending on the input you have.

Calculation of regression constant för calculation of rain intensities…

Calculation of regression constant för calculation of rain intensities for the whole World

Calculation of a regression constant for calculating rainfall intensities I (l/s/ha) for the entire World has been implemented in the box Design flow in StormTac Web. The function is derived from the equation developed by Dahlström (2010) and uses a target search (goal seek) function to iterate a regression constant, alpha, which controls the rain intensities over input data in the form of selected return time (year), specified rain durations (min) and rain intensities (l/s/ha). The generated regression constant alpha can be used for rain intensities for optional rainfall durations and replaces the default values in the model. The result will be different local/regional rainfall intensities used to calculate design flows and the required flow detention volume. If you want the model to always start with a calculated regression constant, you can manually enter it under the sheet (tab) Settings, but this should not be done if the license is used by offices in different locations.

Alternatively, you can, as before, manually enter each rain intensity for specified durations in the boxes (tables) at the boxes Design flow and Flow detention. The latter provides more accurate values, but the alpha value can be used for all return times.

Release v19.4.1