FIELD TESTING AND EVALUATION OF DUST DEPOSITION AND ...

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1. INTRODUCTION 1.1 Background The Western States Air Resources Council (WESTAR) contracted the Desert Research Institute (DRI) and the University of Utah (U of U), through subcontract, to perform an investigation of a model that has been proposed by Dale Gillette of NOAA(Countess, 2001) to account for near-source deposition of dust emissions from unpaved roads. This work was motivated by the well-documented disagreement between estimates of road and other geological dust obtained by emissions inventory methods and the actual amount of inorganic minerals observed on filter samples at ambient monitoring sites (Watson and Chow, 2000). This WESTAR-funded project leveraged two existing DoD funded studies (CP 1190, CP 1991) to increase the utility of data collection and analysis in the context of meeting the objectives of this study. 1.2 Objectives Broadly, the goal of this study was to provide insight into the magnitude of PM 10 dust removal by deposition close to the emission source. The analysis was intended to focus on emissions from unpaved roads, though the results may be pertinent to other sources of fugitive dust. The specific objectives of the study were: 1. Provide recommendations for feasibility of the Gillette Box Model as a tool for correcting emissions inventories for fugitive dust from unpaved roads and suggest possible modifications that may improve model performance. 2. Compare the results of field studies with the Box Model and with the algorithm used in ISC3. 3. Provide recommendations for modeling PM 10 dust deposition and removal and suggest areas to target in future work 1.3 Approach To achieve the stated objectives, this project drew on two field studies with robust datasets, three modeling approaches, and a review of the mechanisms of deposition and dispersion and their parameterization in air quality models. The first field test took place at the Ft. Bliss military facility near El Paso, TX. The setting was representative of the desert Southwestern United States. Atmospheric conditions ranged from near-neutral to moderately unstable. The second field test was conducted at the Dugway Proving Ground as part of the Mock Urban Experiment. The setting was representative of areas with large roughness elements, similar to suburban tract homes. Atmospheric conditions were stable. The three models evaluated were the Gillette Box Model, a Gaussian plume model similar to that used in EPA’s ISC, and a numerical solution to a simplified version of the Atmospheric Diffusion Equation (ADE). Predictions from all three models were compared with the data from the field studies. 1-1
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: LIST OF TABLES Table 2-1. Parameter
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 and 80:
100% 90% 80% Relative Frequency (pr
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average wind speed measured at 12 m
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
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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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