Updated standard concentrations for the sum of PAH16 and…

Updated standard concentrations for the sum of PAH16 and individual PAHs, especially for rural areas

Updated values for standard concentrations for stormwater and base flow for PAH16 and respective individual PAHs for all rural types of land use such as woodland and meadows etc. and also for allotment area. Many values were previously stated as 0 in concentration for the individual PAHs, which have now been updated with estimated concentration data, which is lower than for other land uses, but this will give slightly higher estimated total concentrations and loads than before if these land uses are used.

The updated concentration data are marked in the database and implemented for new projects that are started as from 2019-05-27.

Calculation of acceptable concentration from development areas

Calculation of acceptable concentration from development areas

Based on calculated acceptable load (kg/year) and calculated flow, an acceptable concentration (µg/l) from the area is also calculated, which can also be used as a limit value. It is possible to check an outlet concentration after measures and compare with this limit value, which can give answers to whether the acceptable load is achieved for the area or if additional measures are needed.

This calculated acceptable concentration requires a recipient calculation, with input of area/land use in the recipient watershed area, and also inputs of area and volume of the receiving water, with advantage also measured concentration data from the receiving water body (see the guide).

Revised function for runoff from the land use surface…

Revised function for runoff from the land use surface water within the summed (sub)watershed areas

The revision effects the following calculated values:

– total concentration from summed (sub)watershed areas presented in the MR-report, where surface water is included as land use in one or more of the (sub)watershed areas, which before resulted in wrong values but now this is corrected.

– the runoff coefficient and the runoff (l/s) in areas that include the land use surface water.

The revision does not effect calculated concentrations and loads from each separately calculated area, even if surface water is included! The revision does not effect the results in the recipient model!

Automatical calculation of sewer inner diameter based on Qdim,…

Automatical calculation of sewer inner diameter based on Qdim, slope and material selection

Previously, in the box “Sewer” you needed to test different inner diameters to cope with the design flow.
A new function has been created which automatically calculates the inner diameter and gives a recommendation on pipe dimension.
This calculation can now be done in the box Sewer where a new section has been added.
Supplements have been made in report 2. Transport and flow detention.

New equation for designing required detention volume at heavily…

New equation for designing required detention volume at heavily throttled outlets

The rain intensity I was previously calculated with Dahlström’s equation (Dahlström, 2010) for all durations, but at extremely throttled outflows, it may be the question of durations that are 24 hours or longer before the required maximum detention volume is obtained.

For such long durations, from one to four days, the intensity is now calculated according to Dahlström (1979). This procedure is in accordance with P110 (Svenskt Vatten, 2016).

This results in lower intensity at design durations ≥ 24 hours than previous method gave, but the same as before in most cases (<24 hours). Before, the maximum required level of flow detention could not be achieved up to 4 days, but the new values for rain intensity (l/s/ha) mean that maximum volume can be achieved at lower outflows. This results in a lower detention volume being required than before at extremely throttled outlets where the design rain duration is ≥ 24 hours.

Automatical calculation of studied flow (l/s) from input share…

Automatical calculation of studied flow (l/s) from input share of the yearly runoff volume.

Before, different values of the studied flow were tested in the box Design flow until it resulted in a certain share of the yearly runoff volume. A new function has now been created which automatically calculates the flow for a given share. This is done by clicking on a symbol to the right of the Design flow box. In the form that is then opened, you fill in the share by which the flow is automatically calculated and will be entered in the model’s box Design flow.

Normally, the studied flow is set to include 90% (80-90%) of the yearly runoff volume.

New standard concentrations and revised min and max reduction…

New standard concentrations and revised min and max reduction efficiencies

– Reduced standard concentrations for phosphorus from Meadows and Woodland and meadows after comparing with other land uses.

– Revised min and max treatment effects of various types of treatment facilities for certain substances after an investigation of all values. The revisions are reported in the database.

These changes apply to new projects created from 2019-03-21. The changed values are also displayed in the updated database. You can enter the values for the standard phosphorus levels manually in existing projects.

Relase notes v19.1.2

Relase notes v19.1.2

Revision of standard concentrations ​​for phosphorus (P)

Updated values ​​for phosphorus for several land uses:
– reduced for e.g. terraced house area and multi-family area.
– increased for roof, yard area within block and park grounds.

Management of existing or planned actions upstream is added.

Area on watershed area upstream
A new input field for areas upstream has been added to the “Recipient data” box.
Affects only the area’s acceptable load (Lacc,area) and listed as Arec.ext “Extra catchment area upstream (ha)”

Cost model in StormTac data base

Cost model in StormTac data base

A cost model for all designed facility types is now available in Stormtac database, with references and a large number of facility details, e.g. pipes, wells (drain inlets), plants (vegetation), filling materials, shafts and pumping stations. These can be cost-calculated at a general level, without regard to site-specific conditions.

Standard, minimum and maximum costs are calculated based on input data in the form of number, length, area (m2) or volume (m3). The calculation is performed directly in the database.