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

16:33:27

*** 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 **