StormTac

Last updated: 2008-05-11

Flowchart (print screen) for the storm water model StormTac.

System requirements and user information

 

-         Microsoft Excel 2000 or later is required.

-         English is the model language (however it is from the flowchart possible to get a Swedish flowchart and translation of some words from English to Swedish).

-          The number format in Windows must be points and decimals in the model must be written in points

Background

Metals and nutrients are examples of pollutants in storm water which may cause toxic and eutrophic effects in the receiving waters. StormTac is the tool that can help You towards a more sustainable storm water management. 

Areas of implementation

StormTac can help you to: 

  • calculate storm water runoff volumes, pollutant concentrations and loads in the discharge points and from different land uses.
  • compare measured/sampled data to calculated values.
  • identify the largest pollutant sources and discharge locations to a recipient. 
  • set up water and mass balances for receiving waters.
  • estimate the acceptable recipient loads and the reduction needed.
  • identify and decide where to implement Storm water Treatment Facilities (STFs) and detention facilities, such as wet ponds, filter strips, constructed wetlands, ditches/ swales and detention basins.
  • choose and design (area and volume) STFs and detention facilities. 
  • estimate the effectiveness of the designed STF or an existing STF and its effects on the recipient (reduced concentration values).
  • calculate the capacity of storm water sewers.
  • calculate loads from different pollutant sources such as wet and dry deposition, road wear, tyre wear, copper and zinc surfaces.

  Some unique properties

  1. simple to use (Excel 2000 format, taking advantage of VBA using clickable boxes and input forms in the flowchart).
  2. requires little input data and no manual (help notes are included in the file), however a short manual that let you begin quickly (“within one hour”) with the calculations is included.
  3. considers both point and diffuse loadings, base flow and atmospheric deposition.
  4. integrates watershed and runoff properties with treatment/ detention facilities and impacts on receiving waters.

The model results are presented in a flowchart (see above), in tables and diagrams. They can also be and have been linked to other databases and GIS, see e.g.  http://www.tyreso.se/pubdoc/forv/msf/Kommunaltekniska/dagv/index.htm

 Databases

StormTac includes databases with precipitation data, runoff coefficients, concentration data and reduction efficiencies.

 Required input data

The model requires very little input data. Watershed area (ha) per land use (e.g. houses, roads and forests) is the only obligatory input data. The traffic intensity (vehicles/day) is needed if studying the loads from larger roads within the catchment area. The area and volume of the receiving water are needed for estimating allowable loads. If the sub model “Source model” is to be used then added input data are road length (m) and material areas (m2). The included databases help to make more accurate analyses by letting you change other input data such as precipitation (mm/month or mm/year), runoff coefficients and water depths.

The model parameters can be calibrated to measured data to ensure site specific conditions being considered. In such cases further input data consist of measured flow (m3/year or m3/month), precipitation (mm/year or mm/month) and sampled concentration (mg/l or ug/l).

Calculation methods

The main methodology has been reviewed internationally through scientific papers and a doctoral thesis. The spreadsheet Excel model has been developed to automate the calculations by using land use specific standard values. It is best suited for long-term predictions. Runoff water flow is calculated from precipitation data and land use specific runoff coefficients and areas. Pollutant load rate (kg/year) is quantified from calculated flow and from standard concentrations. 

The standard concentrations are estimated empirically from a large set of flow proportional field sampling data, which contributes to their general applicability.

StormTac includes a large amount of sub models and equations for the design of different storm water facilities. The user can choose between a relatively detailed and a quick, simple design. The resulted dimensions by using different methods and by changing parameter values can easily be reviewed and compared. Examples of included design parameters are runoff coefficients, land use areas, facility permanent water depth, water depth of detention volume, slope, rain depth, outflow, emptying time and reduction efficiency.

The design methods have been employed for a large number of case studies from pre studies to final detailed construction drawings.

Case studies

StormTac has been used for example in the following case studies, where * indicates that calibration or comparison to measured data has been performed: Nybohov*, Stockholm (residential); Essingeleden*, Stockholm (road); Sätra*, Stockholm (residential); Lake Flaten*, Salem (residential); Flemingsbergsviken*, Huddinge (mixed); Tyresö municipality (mixed); Upplands Väsby municipality (mixed); Lake Edsviken and Lake Norrviken, Sollentuna (mixed), Lidingö municipality* (mixed); Karlstad municipality (mixed); Fittja, Botkyrka (residential); Reykjavik, Iceland (residential); Kaliningrad, Russia (road) and Lake Titicaca, Peru and Bolivia (mixed).

 

Standard concentrations, StormTac, version 2008-04

http://www.stormtac.com/

 

 

 

 

 

 

 

Median

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Land use

Runoff coeff.

P

N

Pb

Cu

Zn

Cd

Cr

Ni

Hg

SS

oil

PAH

BaP

COD

Fe

BOD

TOC

Arsenic

DOC

Urban

-

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

Roads (5 000 ADT)

0.85

0.14

1.65

14

31

62

0.24

1.0

1.15

0.1

79

0.2

0.672

0.007

25

1.4

5

21

2.4

21

Roads (10 000 ADT)

0.85

0.18

1.8

17

51

89

0.28

1.8

1.8

0.1

89

0.3

1.064

0.014

50

3

10

25

2.4

21

Roads (30 000 ADT)

0.85

0.24

2.4

31

72

197

0.44

5.0

4.4

0.1

115

1.0

1.504

0.042

100

5

15

30

2.4

21

Roads (100 000 ADT)

0.85

0.31

4.5

80

94

575

1

16.2

13.5

0.1

206

3.4

1.985

0.14

225

8

25

47

2.4

21

Parkings

0.85

0.1

1.1

30

40

140

0.45

15

4

0.1

140

0.8

1.7

0.06

150

6

1.7

20

2.4

14

Houses

0.25

0.2

1.4

10

20

80

0.5

4

6

0.2

45

0.4

0.6

0.1

65

1.7

9

10

3

7

Row houses

0.32

0.25

1.45

12

25

85

0.6

6

7

0.2

45

0.6

0.6

0.1

75

3

9

12

3

8

Apartments

0.45

0.3

1.6

15

30

100

0.7

12

9

0.2

70

0.7

0.6

0.1

85

5.6

9

20

3

14

Leisure houses

0.2

0.46

3.3

5

20