FIELD TESTING AND EVALUATION OF DUST DEPOSITION AND ...

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highest attainable value and then decreased incrementally to the minimum value. This cycle was then repeated as time allowed. Test vehicles paused for approximately one and a half minutes between passes to allow for the dust plume to clear all three downwind towers. The schedule and test conditions are summarized in Table 5-1. Table 5-1. Test dates, times, vehicles, data recovery, and conditions during the FT. Bliss, April 2002 field campaign. Date 4/11/2002 4/11/2002 4/12/2002 4/12/2002 4/15/2002 4/15/2002 4/16/2002 4/16/2002 4/16/2002 4/17/2002 4/18/2002 4/19/2002 4/22/2002 4/23/2002 4/24/2002 4/24/2002 Time 13:44 - 14:51 15:11 - 16:06 14:41 - 15:21 15:35 - 16:13 10:38 - 12:37 12:48 - 13:30 10:57 - 12:26 13:53 - 15:35 17:18 - 19:20 10:22 - 12:36 10:56 - 13:15 11:06 - 14:29 9:47 - 10:08 13:38 - 15:11 10:50 - 12:33 13:41 - 15:16 Equipment status DT3 only, No wind direction data DT3 only, No wind direction data DT3 only DT3 only DT1, DT2, DT3 DT1-partial, DT2, DT3 DT1, DT2, DT3 DT2, DT3 DT1, DT2, DT3 DT1, DT2, DT3 DT1, DT2, DT3 DT1-partial, DT2, DT3 DT1, DT2, DT3 DT1-partial, DT2, DT3 DT1, DT2, DT3 DT1, DT2, DT3 Vehicle HUMVEE Dodge Caravan Dodge Caravan Dodge Neon Ford Taurus U-Haul Dodge Caravan 5-ton truck 1979 Chevy van (TRAKER) LMTV Hemmet 22 Freightliner Dodge Neon 22 Freightliner 1979 Chevy van (TRAKER) Vehicle speeds (km/hr) 8, 16, 24, 32, 40, 48, 56, 64, 72 16, 32, 48, 64, 81 Total number of valid passes 26 Wind conditions Light and variable with small westerly componenet 40 South -West 48 30 Light and variable 16, 24, 32, 48, 64, 81 16, 32, 48, 64, 81 16, 32, 48, 64 16, 32, 48, 64, 81 16, 32, 48 ,64 16, 24, 32, 40, 48, 64 16, 32, 48, 64, 81 16, 32, 48, 64 16, 24, 32, 40, 48, 56 16, 32, 48, 64 16, 24, 32, 40, 48, 56 16, 24, 32, 40, 48, 56 HUMVEE 16, 64 2 12 Light and variable 23 South -West 11 South -West 29 South -West 27 South -West 46 South -West 16 South -West 16 South -West, with gusts 11 South -West, with gusts 0 South: Test suspended 18 West, with gusts 0 Light winds from the North. No valid data obtained Winds light and variable. Data recovery poor. The unpaved road at Ft. Bliss was 1 kilometer in length and oriented in the northsouth direction, with the three towers lined perpendicular to and east of the road. Thus, when winds did not have a strong westerly component, the dust plume generated by passing vehicles did not travel in the direction of the towers. The transport time between the road and the far downwind tower (100 m) was estimated to be approximately 30 seconds. One-second wind direction data were averaged for the 30 seconds prior to plume impact at the far downwind tower. If the average direction fell in the quadrant spanned by the northwest and southwest vectors, the corresponding vehicle pass was considered valid. Vehicle passes corresponding to wind directions that were not in the northwestsouthwest quadrant were considered suspect and not included in subsequent data analysis. Note that for westerly winds, a 30-second transport time corresponds to a wind speed of 3.3 m/s while for southwesterly or northwesterly winds, it corresponds to 4.7 m/s. The 5-6
average wind speed measured at 12 meters over all emissions tests was 6.2 m/s. Thus, a transport time of 30 seconds is probably, on average, a conservative overestimate. The wind speed and direction were measured only at the far downwind tower (DT_3). Therefore, for using Equation 5-1, it was necessary to use wind speeds and directions measured at DT_3 for DT_1 and DT_2. The possibility of introducing errors by this method was examined. The horizontal PM 10 fluxes were calculated for DT_3 only and averaged over the test vehicle speed. This procedure was performed twice, once with wind data that corresponded to the time of the passing of the dust plume, and once with wind data that was retarded by 30 seconds. For example, the flux at 13:30:00 was calculated using wind data measured at 13:30:00 and also with wind data measured at 13:29:30. The purpose of this exercise was to subject the flux calculations for DT_3 to the same uncertainties that the data from DT_1 and DT_2 would be experiencing. In comparing the two resultant sets of horizontal fluxes, no significant difference were found (slope = 1.01, R 2 =0.98, n=53, intercept was forced to 0), indicating that the use of DT_3 wind direction and wind speed to calculate horizontal fluxes of PM 10 at DT_1 and DT_2 would not introduce errors. 5.1.2 Sonic Anemometer Tests A three-dimensional sonic anemometer (“A” style probe, applied Technologies Inc) was used to assess the effect of vehicle size on the initial distribution of the dust plume generated. The anemometer was first collocated with the cup anemometer and the wind vane at the 12.2 m height on DT_3 for three sample days (4/18/02 – 4/20/02). The sonic anemometer was set to measure the U, V, and W components (corresponding to the x, y, and z directions) of the velocity at a frequency of 10 Hz. Figure 5-5 shows the comparison between wind speeds measured with the cup anemometer and a sonic anemometer; part a. shows a time series; parts b. through d. show comparisons of 1- second averages and 1-minute averages. In general, the cup and the sonic anemometers track each other well, though the sonic anemometer gives smaller values of wind speed as indicated by the slopes of the regressions in Figure 5-5 b-d (0.91 – 0.94). The significant improvement in R 2 values between the 1-second (0.84-0.89) and 1-minute averaged data (≥ 0.98) is to be expected since the cup anemometer has a nominal response time of 1 second (approximately the time required to register 1/3 of the difference between changes in wind speed) while the sonic anemometer response is practically instantaneous. On 4/21/02 between 19:44 and 22:15 a series of tests were conducted to assess the magnitude of the turbulent wake behind a passing vehicle. The tests occurred at night because under stable nighttime atmospheric conditions, the turbulence generated by a vehicle can be more readily identified with a sonic anemometer than when the atmosphere is unstable and the background turbulence level is much higher. The downwind tower closest to the unpaved road was moved to the edge of the road. Two markers were placed on the unpaved road, one at a distance of 2 meters from the edge of the road (and the tower) and the other at a distance of 6 meters. The sonic anemometer was mounted on the tower at a height of 0.9 meters above ground level (AGL) and protruded 1.1 meters towards the road (i.e. approximately 1 meter from the near marker). Three vehicles with considerably different profiles were tested: a Dodge Neon, a 1979 Chevy cargo van, and a 24-foot moving truck. Each vehicle was driven through the two markers on the road once heading north and once heading south at 16, 32, 48, and 64 5-7
Page 1:
FIELD TESTING AND EVALUATION OF DUS
Page 5 and 6:
EXECUTIVE SUMMARY The Western State
Page 7 and 8:
models. Countess (2001) summarized
Page 9 and 10:
TABLE OF CONTENTS 1. INTRODUCTION 1
Page 11 and 12:
TABLE OF FIGURES Figure 2-1. Develo
Page 13 and 14:
Figure 4-6. The fraction of particl
Page 15 and 16:
Figure 5-16. Comparison of fraction
Page 17 and 18:
LIST OF TABLES Table 2-1. Parameter
Page 19 and 20:
1. INTRODUCTION 1.1 Background The
Page 21 and 22:
2.BACKGROUND Fugitive dust is emitt
Page 23 and 24:
Planetary Boundary Layer (PBL) F =
Page 25 and 26:
C D u* = ur The overall drag c
Page 27 and 28:
St a vg u g = cA L * Equation 2
Page 29 and 30: Table 2-1. Parameters used in the S
Page 31 and 32: 1E+01 1E+00 z0 = 4.4 cm z0 = 6.4 cm
Page 33 and 34: pathway for deposition for particle
Page 35 and 36: An alternative method for modeling
Page 37 and 38: 3. MEASUREMENT OF DEPOSTION VELOCIT
Page 39 and 40: Department at the University of Uta
Page 41 and 42: In the laboratory, the deposited ma
Page 43 and 44: Table 3-2. Log of all flat substrat
Page 45 and 46: 16 Normalized Deposition Velocity 1
Page 47 and 48: 1.E+05 Deposition Velocity - cm/s 1
Page 49 and 50: are deposition from a horizontally
Page 51 and 52: single element that is intended to
Page 53 and 54: 4. MODELS USED TO STUDY PARTICLE RE
Page 55 and 56: κu ( ) * z 8 fz K zz = exp −
Page 57 and 58: C = −6 ( 1× 10 ) QV 2π u s σ
Page 59 and 60: oad. M is the mass of particles in
Page 61 and 62: By making the approximation that dm
Page 63 and 64: diameters less than 10 microns. Dis
Page 65 and 66: of such a height is somewhat arbitr
Page 67 and 68: 1 0.9 0.8 1 0.9 0.8 Fraction remain
Page 69 and 70: Fraction of Particles Remaining in
Page 71 and 72: gravitational settling. Stable cond
Page 73 and 74: though it is expected to improve at
Page 75 and 76: 5. DETERMINATION OF PARTICLE REMOVA
Page 77 and 78: PM 10 measured by the DustTrak must
Page 79: 100% 90% 80% Relative Frequency (pr
Page 83 and 84: where the subscript i indicates tha
Page 85 and 86: k C int = peakend k C peeakstart d
Page 87 and 88: Height z (m) 14 12 10 8 6 T1_data T
Page 89 and 90: Horizontal fluxes of PM 10 measured
Page 92 and 93: Table 5-2 enumerates the speed-depe
Page 94 and 95: 6 Ratio of AP-42 Emission Factor to
Page 96 and 97: to the ground) giving an approximat
Page 98 and 99: models analyzed in this study is su
Page 100 and 101: Table 6-1. Screen analysis of test
Page 102 and 103: value which was used up to the midp
Page 104 and 105: measured at 3,1. Downwind the dust
Page 106 and 107: trips, the average readings for the
Page 108 and 109: Fraction of particles of stated siz
Page 110 and 111: the ground, where particles have a
Page 112 and 113: particles through the top of the bo
Page 114 and 115: deposition. Much of the decrease in
Page 116 and 117: 7-8
Page 118 and 119: Gifford, F.A. (1961). Use of Routin
Page 120: Venkatram, A. (1993). The Parametri
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