TSCREEN EPA's Air Pollution Dispersion Model (9/26/08)

TSCREEN EPA's Air Pollution Dispersion Model (9/26/08)

Procedure for installing TSCREEN on your computer hard drive

1. Establish and identify a new file on your computer (suggest naming it TSCREEN)

2. Got to the EPA internet web site http://www.epa.gov/ttn/scram

3. Click on "Air Quality Models", http://www.epa.gov/scram001/aqmindex.htm

then "Dispersion Models" http://www.epa.gov/scram001/dispersionindex.htm

then "Screening Tools" http://www.epa.gov/scram001/dispersion_screening.htm

4. Scroll down the "Screening Models" page and download the TSCREEN model code "Code/Executable Test Case" , Model Code
Code/Executable/Test Case (1.6MB,ZIP) which is a zipped file. Download this file to your PC and put it in a named file (suggest naming the file “TSCREEN”) .

5. You need a program to unzip the TSCREEN file and you can obtain Pkunzip from the EPA internet site at http://epa.gov/ttn/tools.html. Download the Pkunzip.exe to your TSCREEN file on your computer. You can also use other unzip software.

6. With "Pkunzip" you need to be in the C:\ command prompt if you are using the Windows software such as Windows XP. The "Command prompt" is in the Accessories. Click on "Start", then click on All Programs, then go to "Accessories", click on the "Command Prompt", Type "cd\", then press the enter key. This should show all the files in your hard drive. Then enter your TSCREEN file by typing cd\TSCREEN next to the c:\. and press Enter. The screen will appear like:

c:\.cd\TSCREEN and then press Enter and you will be in the TSCREEN file.

To unzip the file with Pkunzip, type Pkunzip TSCREEN.ZIP and unless EPA has changed it, 5 zipped files will be formed (TSCRCODE.ZIP, TSCREEN1.ZIP, etc). Unzip all the remaining zipped files.

Then you can type "TSCREEN" and press enter and the TSCREEN program will start. This is for operating TSCREEN inside the pseudo MS DOS format. However, you can also operate TSCREEN inside Windows.

When saving your TSCREEN results, you might need to save them in a MS Word file.

There is an example TSCREEN (actually SCREEN3 which is inside of TSCREEN) calculation of air pollutant concentrations downwind of the asbestos plant stack in Libby Montana are shown below.

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Problem: Libby Montana Asbestos Mill

Given

Stack height = 61 meters Pollutant Emission Rate = 52.5 grams/sec.

Stack Inside Diameter = 1.5 meters Stack exit gas velocity = 12.92 meters/sec

Stack gas exit temp = 400 degrees K Ambient air temp = 293 degrees K

Rural Option Receptor Height = 0

Assume the asbestos particles are small and behave like gases

Find:

a) Maximum 1 hr, 24 hr, and annual average particle air pollutant conc. assuming flat terrain

b) Downwind location of maximum air pollutant concentration

c) Atmospheric stability class at maximum air pollutant concentration

________________________________________________________________________________

Problem Libby Montana Asbestos Mill

Given:

Stack height = 61 meters

Pollutant emission rate = 52.5 grams/sec.

Stack inside diameter = 1.5 meters

Stack gas exit velocity = 12.92 meters/sec

Stack gas exit temperature = 400 degrees K

Ambient air temp = 293 degrees K

Rural option

Receptor height = 0

Assume the asbestos particles are small and behave as a gaseous emission.

Find:

a) Maximum 1 hr, 24 hr, and annual average air pollutant concentrations assuming level flat terrain.

b) Downwind location of maximum air pollutant concentration.

c) Atmospheric stability class at maximum air pollutant concentration

The TSCREEN calculation results of April 12, 2004 are shown below:

04/12/04

*** SCREEN3 MODEL RUN ***

*** VERSION DATED 95250 ***

Libby Montana Asbestos Mill

SIMPLE TERRAIN INPUTS:

SOURCE TYPE = POINT

EMISSION RATE (G/S) = 52.5000

STACK HEIGHT (M) = 61.0000

STK INSIDE DIAM (M) = 1.5000

STK EXIT VELOCITY (M/S)= 12.9200

STK GAS EXIT TEMP (K) = 400.0000

AMBIENT AIR TEMP (K) = 293.0000

RECEPTOR HEIGHT (M) = .0000

URBAN/RURAL OPTION = RURAL

BUILDING HEIGHT (M) = .0000

MIN HORIZ BLDG DIM (M) = .0000

MAX HORIZ BLDG DIM (M) = .0000

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*** SUMMARY OF SCREEN MODEL RESULTS ***

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CALCULATION MAX CONC DIST TO TERRAIN

PROCEDURE (UG/M**3) MAX (M) HT (M)

-------------- ----------- ------- -------

SIMPLE TERRAIN 319.6 751. 0.

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** REMEMBER TO INCLUDE BACKGROUND CONCENTRATIONS **

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BUOY. FLUX = 19.064 M**4/S**3; MOM. FLUX = 68.779 M**4/S**2.

*** FULL METEOROLOGY ***

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*** SCREEN AUTOMATED DISTANCES ***

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*** TERRAIN HEIGHT OF 0. M ABOVE STACK BASE USED FOR FOLLOWING DISTANCES ***

DIST CONC U10M USTK MIX HT PLUME SIGMA SIGMA

(M) (UG/M**3) STAB (M/S) (M/S) (M) HT (M) Y (M) Z (M) DWASH

------- ---------- ---- ----- ----- ------ ------ ------ ------ -----

5. .0000 1 1.0 1.1 320.0 233.23 5.05 4.79 NO

100. .1167E-07 1 3.0 3.4 960.0 118.41 27.94 15.95 NO

200. 2.886 1 3.0 3.4 960.0 118.41 51.45 31.77 NO

300. 81.50 1 3.0 3.4 960.0 118.41 73.54 50.09 NO

400. 191.7 1 3.0 3.4 960.0 118.41 94.15 73.03 NO

500. 232.1 1 2.0 2.3 640.0 147.11 115.68 107.51 NO

600. 254.0 1 1.0 1.1 320.0 233.23 141.69 161.61 NO

700. 313.2 1 1.0 1.1 320.0 233.23 160.06 218.93 NO

800. 315.4 1 1.0 1.1 320.0 233.23 178.32 287.25 NO

900. 293.0 1 1.0 1.1 320.0 233.23 196.45 366.45 NO

1000. 268.9 1 1.0 1.1 320.0 233.23 214.43 456.51 NO

1100. 248.3 1 1.0 1.1 320.0 233.23 232.26 557.47 NO

1200. 230.7 1 1.0 1.1 320.0 233.23 249.95 669.40 NO

1300. 215.6 1 1.0 1.1 320.0 233.23 267.50 792.36 NO

1400. 202.4 1 1.0 1.1 320.0 233.23 284.91 926.45 NO

1500. 190.8 1 1.0 1.1 320.0 233.23 302.19 1071.73 NO

1600. 184.6 2 1.0 1.1 320.0 233.23 239.50 189.54 NO

1700. 186.2 2 1.0 1.1 320.0 233.23 252.22 201.73 NO

1800. 186.2 2 1.0 1.1 320.0 233.23 264.88 214.03 NO

1900. 184.7 2 1.0 1.1 320.0 233.23 277.47 226.44 NO

2000. 182.1 2 1.0 1.1 320.0 233.23 290.00 238.94 NO

2100. 178.8 2 1.0 1.1 320.0 233.23 302.47 251.54 NO

2200. 174.8 2 1.0 1.1 320.0 233.23 314.88 264.22 NO

2300. 170.5 2 1.0 1.1 320.0 233.23 327.23 276.97 NO

2400. 165.9 2 1.0 1.1 320.0 233.23 339.52 289.80 NO

2500. 161.3 2 1.0 1.1 320.0 233.23 351.76 302.70 NO

2600. 156.7 2 1.0 1.1 320.0 233.23 363.94 315.67 NO

2700. 152.2 2 1.0 1.1 320.0 233.23 376.07 328.69 NO

2800. 147.9 2 1.0 1.1 320.0 233.23 388.15 341.78 NO

2900. 143.7 2 1.0 1.1 320.0 233.23 400.18 354.92 NO

3000. 139.6 2 1.0 1.1 320.0 233.23 412.17 368.12 NO

3500. 138.5 3 1.0 1.2 320.0 224.13 323.93 197.86 NO

4000. 133.5 3 1.0 1.2 320.0 224.13 364.46 222.22 NO

4500. 126.5 3 1.0 1.2 320.0 224.13 404.50 246.44 NO

5000. 118.7 3 1.0 1.2 320.0 224.13 444.09 270.51 NO

5500. 111.0 3 1.0 1.2 320.0 224.13 483.27 294.45 NO

6000. 103.7 3 1.0 1.2 320.0 224.13 522.07 318.26 NO

6500. 97.04 3 1.0 1.2 320.0 224.13 560.51 341.93 NO

7000. 91.08 3 1.0 1.2 320.0 224.13 598.63 365.48 NO

7500. 85.76 3 1.0 1.2 320.0 224.13 636.43 388.91 NO

8000. 83.42 5 1.0 1.9 10000.0 125.30 333.97 72.99 NO

8500. 83.38 5 1.0 1.9 10000.0 125.30 352.50 75.12 NO

9000. 83.02 5 1.0 1.9 10000.0 125.30 370.90 77.19 NO

9500. 82.39 5 1.0 1.9 10000.0 125.30 389.18 79.21 NO

10000. 81.55 5 1.0 1.9 10000.0 125.30 407.34 81.18 NO

15000. 68.20 5 1.0 1.9 10000.0 125.30 583.68 97.31 NO

20000. 56.16 5 1.0 1.9 10000.0 125.30 752.55 110.84 NO

25000. 46.83 5 1.0 1.9 10000.0 125.30 915.84 120.28 NO

30000. 39.95 5 1.0 1.9 10000.0 125.30 1074.70 128.63 NO

40000. 31.89 6 1.0 2.7 10000.0 108.30 920.32 75.71 NO

50000. 27.75 6 1.0 2.7 10000.0 108.30 1117.50 80.34 NO

MAXIMUM 1-HR CONCENTRATION AT OR BEYOND 5. M:

751. 319.6 1 1.0 1.1 320.0 233.23 169.57 253.09 NO

DIST = DISTANCE FROM THE SOURCE

CONC = MAXIMUM GROUND LEVEL CONCENTRATION

STAB = ATMOSPHERIC STABILITY CLASS (1=A, 2=B, 3=C, 4=D, 5=E, 6=F)

U10M = WIND SPEED AT THE 10-M LEVEL

USTK = WIND SPEED AT STACK HEIGHT

MIX HT = MIXING HEIGHT

PLUME HT= PLUME CENTERLINE HEIGHT

SIGMA Y = LATERAL DISPERSION PARAMETER

SIGMA Z = VERTICAL DISPERSION PARAMETER

DWASH = BUILDING DOWNWASH:

DWASH= MEANS NO CALC MADE (CONC = 0.0)

DWASH=NO MEANS NO BUILDING DOWNWASH USED

DWASH=HS MEANS HUBER-SNYDER DOWNWASH USED

DWASH=SS MEANS SCHULMAN-SCIRE DOWNWASH USED

DWASH=NA MEANS DOWNWASH NOT APPLICABLE, X<3*LB

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*** USER SPECIFIED AVERAGING TIMES ***

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ESTIMATED MAXIMUM CONCENTRATION FOR 24 HR AVERAGING TIME:

127.84 (+/- 63.92) UG/M**3

ESTIMATED MAXIMUM CONCENTRATION FOR ANNUAL AVERAGING TIME:

25.568 (+/- 6.392) UG/M**3

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*** END OF SCREEN MODEL OUTPUT **