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AIR QUALITY IMPACT ANALYSIS

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1. Stationary IC engines diesel 0 96 Stationary IC engines gas 0 99 Vehicular sources diesel 0 96 Vehicular Sources gas 0 99 bs Height of Source Above Surface stkhgt dy Construction Combustive Emissions Combustive emissions from construction activities are to be modeled as ground based volume sources stkhgt 0 ii Operational Fugitive Emissions ROC fugitive emissions emanating from numerous levels covering the same ground surface area are to be modeled as a volume source with the height of emissions stkhgt being set equal to the lowest level of the fugitive emissions Cx Initial Vertical Dimension SIGMA Z0 input as szinit A Constructive Combustive Emissions The vertical dimension of a ground based volume source is to equal the mass emission weighted plume rise of all the combustive sources contained within the volume source being modeled To calculate the vertical dimension each individual source within the ground based volume source being modeled is to be examined Use RTDM to determine the plume height from each source Refer to Section IV for the specification of the model options For 22 AQIAGDLS WP5 JUNE 1996 Rev 2 ground based volume sources the final plume height is equal to the final plume rise Final plume rise is to be used for calculating the vertical dimension of the volume source as a weighted average of the sources
2. Fumigation Modeling Background Air Quality Ozone Limiting Method Use of Background Air Quality for Pollutants Other Than NO 40 aa O WOO OO OV O O O BE W N NN N H OO JT BEWWN B Use of Background Air Quality for NO IX Receptor Grid Spacing A General Requirements B Model Specific Requirements Xe Modeling of Emission Reduction Credits Offsets XI References LIST OF TABLES TABLE 1 Generic Project Scenarios and Required Modeling Analyses TABLE 2 Meteorological Data Format TABLE 3 Main Model Options for OCD Simulations TABLE 4 Typical Surface Roughness Lengths for Various Ground Covers TABLE 5 Additional Meteorological Data Options for OCD Simulations TABLE 6 Reasonable Worst Case Meteorological Data Set for OCD Simulations TABLE 7 Factors to Convert One Hour Modeled Concentrations to Longer Averaging Periods 12 30 31 37 38 39 Abbreviations and Acronyms AQIA Air Quality Impact Analysis ATC Authority To Construct BPI Bits per inch CAAQS California Ambient Air Quality Standard CARB California Air Resources Board COMPLEX I Complex Terrain Model for Point Sources District Santa Barbara County Air Pollution Control District EPA Environmental Protection Agency g s Grams per Second GEP Good Engineering Practice ISCST Industrial Source Complex Short Term Model K Degrees Kelvin m Meters m s Meters Pe
3. 2 Input Parameters To invoke the building downwash algorithms 36 direction specific building heights Dsbh and widths Dsbw in meters beginning with the 10 degree flow vector and incrementing by 10 degrees in a clockwise direction have to be input for the keywords BUILDHGT and BUILDWID respectively in the Source Pathway cards When assessing building downwash effects it is important to submit a plot plan of the project so the District can verify the building parameters used in the analysis D Meteorology Hourly meteorological inputs required by ISCST are wind speed flow vector direction toward which the wind is blowing temperature stability class urban mixing height and rural 11 mixing height The user should not input exponent and vertical potential tempera uses the default values for wind profile exponents and vertical potential temperature gradients For informational purposes the default a function of stability class are 10 wdl5y 2 20 s2dy HBO 30 t the hourly wind profile ture gradient the model AQIAGDLS WP5 JUNE 1996 Rev 2 wind profile exponents as and the default vertical potential temperature gradients as a function of stability class are Hourly wind speed direction from which 0 4 03 4 Og OS u Masy OSD wind direction and temperature are to be obtained from previously approved District preconstruction
4. Lruc e g tform OCD may be used for dependent upon An exception to this requirement occurs if the onshore point source is physically linked to an offshore source supplied by an offshore plat Depending on the particular circumstances both onshore and offshore sources onshore source in question must be wi shoreline to be modeled with OCD be modeled with concurrent point source emissions a the ter of the tion fumigation utant sources except receptor concentrations from different source types in the same model run e g OCD for offshore point source it may be necessary sum together pollutant concent source air quality impact at receptors D Source of Models Technica nformation Service of air qual NTIS and For cases in which two different models are used ISCST for onshore area to use a post processing routine to trations for determining the total ISCST SCREEN OCD and RTDM are available from the National ISCST is part of a library ity simulation models titled User s Network for Applied Models of Air Pollution Version 6 UNAMAP 6 USEPA 1986 All these models can be directly downloaded from the EPA Office of Air Quality Planning and Standards OAQPS Technology Transfer Network TTN electronic bulletin board The telephon number to call to access the OAQPS TTN i
5. may be necessary in the areas wher impacts 3 Complex with the receptor RTDM terrain models require the receptors grid for a complex terrain application locations of importan by calculating the model predicted high it is very t to locate discrete receptors in areas where plume impaction might occur plume ris see Section IV D l a ls are set every 100 intervals are set every Using is owed in using the model 50 meters the input of terrain height along When constructing a This can be done under representative stable conditions and determining where the nearby terrain reaches the same height or greater Otherwise should be followed 4 OCD OCD allows one additional parameter to be entered for each 47 the general requirements discussed above receptor location kilometer of AQIAGDLS WP5 JUNE 1996 Rev 2 the mountain hill elevation in the vicinity of a receptor This value should represent local terrain within one the receptor Since wind directions are set by the user in the reasonable worst case da receptors are placed at all to project if the emissions are all tight cluster of sources tervals on impacts due 100 meter int source cluster ta set the user should take care to ensure that locations likely to produce maximum t emissions sources For offshore s
6. JUNE 1996 Rev 2 expected area of emissions during each applicable averaging period Fugitive hydrocarbon emissions from offshore sources are also to be simulated as multiple point sources covering the xpected area of emissions Onshore non point area line or volume sources such as those produced by construction activities or fugitive emissions should be modeled with the ISCST model see Section V of this manual Onshore projects which do not include offshore emission sources should model point source emissions using ISCST see Sections III of this manual B OCD Model Input Requirements This section discusses principal model input requirements For additional information refer to the OCD User s Guide November 1989 Ws Main Model IOPT Option Specifications Table 3 lists the major model options to be used in simulations with OCD The listed specifications should be used for all submittals to the District Should the applicant wish to employ option specifications other than those listed which do not affect the concentration calculations they may do so with proper notification of the District prior to submission of modeling results 2 Overland Wind and Terrain Options This section of the model input stream requires information concerning the onshore anemometer height the surface roughness length the minimum height of the plume above terrain and the la
7. b Release Height of Area Source Above Surface Relhgt The release height Relhgt of the area source above the surface is to be specified as the height from which the emissions emanate For example all ground based activities which result in fugitive emissions are to be modeled with Relhgt equal to 0 In cases of modeling fugitive emissions as area sources which emanate from an elevated level or deck the value of HS is to equal the height of the level or deck above the ground surface Cs X side Y side and Orientation Angle for an Area Source For a square area source oriented in the north south direction orientation angle 0 only the value for the length of side of the area source need to be entered for the parameter xinit For a rectangular area source the values for the parameters xinit yinit and Angle Angle is orientation from North axis in clockwise direction need to be input An irregularly shaped area source may need to be subdivided into smaller areas of varying shapes sizes and orientation D Scheduling and Averaging Period Considerations Is Onshore Construction Combustive Emissions a Scheduling Methodology For purposes of modeling air quality impacts from construction combustive emissions construction activities are to be analyzed consistent with any operating limitation enforced by permit conditions which specify the period s of the year and or hours of the
8. ter values are not is being utilized worst case the range of values and specify ative humidity is provided JOPT 4 2 if wet bulb temperature is provided 37 AQIAGDLS WP5 JUNE 1996 Rev 2 JOPT 4 3 if dew point temperature is provided If overwater values are not available use the value specified Table 6 for all hours and specify JOPT 4 1 Vv Water surface temperature Use measured water surface temperatures if available and Specify JOPT 6 1 if water surface temperature is provided JOPT 6 2 if air minus water surface temperature is provided If surface water temperature values are not available use the values specified in Table 6 for all hours and specify JOPT 6 2 vi Overwater wind direction shear In all instances this value must be set to 999 9 indicating missing data for all hours and JOPT 7 0 vil Overwater horizontal turbulence intensity Iy Use actual measured hourly values if available and specify JOPT 8 1 If measurements of this parameter are not available specify JOPT 8 0 This will result in allowing OCD to calculate default values of overwater horizontal turbulence intensities If the reasonable worst case meteorological data has been specified as a priority above then the value in Table 6 applies for all hours viii Overwater vertical turbulence intensity Tz Spec
9. the incorporation of offsets in the AQIA is necessary For increment consumption analysis actual emissions decreases from sources occurring after the applicable baseline date should be considered when modeling the total increment consumed 48 AQIAGDLS WP5 JUNE 1996 Rev 2 XI References Aerocomp Inc 1982 PTPLU A Single Source Gaussian Dispersion Algorithm User s Guide Prepared for The Environmental Sciences Research Lab Research triangle Park NC PB83 211235 California Air Resources Board 1987 Information for applying the State Ambient Air Quality Standards for PM o to the permitting of new and modified stationary sources California Air Resources Board Sacramento CA Brode Roger W 1988 Screening Procedures for Estimating the Air Quality Impacts of Stationary Sources EPA 450 4 88 01 0 Cole Henry S and John E Summerhays 1979 A Review of Techniques Available for Estimating Short Term NO2 Concentrations Journal of the Air Pollution Control Association 92 812 817 Dames and Moore 1982 Environmental Report Production Santa Ynez Unit Development for Exxon Company U S A Santa Barbara California October Hanna S Shulman L Paine R and J E Pleim 1984 The Offshore and Coastal Dispersion OCD Model Holzworth G C 1972 Mixing Heights Wind Speeds and Potential for Urban Air Pollution Throughout the Contiguo
10. determine whether building downwash is a factor in the calculation of maximum ground level concentrations There are several circumstances in which building downwash may have a Significant effect on ground level concentrations Some common examples are vents and low stacks with low exit velocities on the top of buildings In these releases pollutants do not have the momentum to escape the wake on the lee side of the building and are thus entrained and downwashed to the ground To determine if downwash may be significant for a particular source the following expression should be applied hs 2 hh 1 Sa Where hs release height of proposed source hp building height a lesser of either the building height or the maximum building width TE he TS greater than or equal to the sum of h 1 5a then downwash is unlikely to occur and will not have to be considered in the analysis If hs is less than the sum of h 1 5a then downwash may be significant and should be addressed in the analysis In some cases nearby buildings may have to be considered A nearby building is one that has a source within five times the lesser of the building height or maximum building width For cases where downwash may be significant and the area has complex terrain both the building downwash and complex terrain screening procedures will have to be applied with the highest concentration to be used
11. General Information Is Model Description The Industrial Sou multiple point sou several types of n sources model and is the version guideline model an rces rce Complex the air quality impacts from a wide with an industrial source complex on point sources such as area There are both short The short term version uses hourly meteorological data required by the District d is part of UNAMAP 6 USEPA user s manual when performing modeling analysis ISC model was designed to assess variety of sources associated In addition to modeling ISC can simulate the dispersion from volume and line term versions of the ISC and long ISCST is an EPA Please refer to the 2 Terrain Applicability This section discusses sources in simple terrain height is less than or equal the use of the ISCST model to assess point intermediate If the the physical release or complex terrain tO height of a source terrain If the then that terrain height terrain is defined as simple is below the plume height but exceeds the physical release rrain for as intermediate t height then that terrain is defined that hour and source For intermediate terrain receptors from both simple terrain algorit algorithm and selects the that hour and that source higher of If the AQIAGDLS WP5 JUNE 1996 Rev 2 ISCST calculates
12. Rev 2 If the applicant has a District approved then the use of tions discussed below applicant does not have a Distric or has an incomplete da the data set according to the fol the data set is If the l overwater values are owing missing and specify use range of values as specified in Table 6 and specify JOPT 1 1 are not available worst case meteorology Table 6 If both overwater and overland wind directions the applicant must use reasonable for all parameters of both the additional meteorological data and overland data sets ii Overwater wind Us JOPT 2 1 available use and specify JOPT 2 1 directions are not available reasonable worst case meteorology speed measured overwater values if available and specify If overwater and overland windspeed values are not the value specified in Table 6 for all hours If both overwater and overland wind the applicant must use Table 6 for all parameters of both the additional meteorological data and overland data sets iiis Use measured overwat meteorological data are specified in Table 6 iv Overwater rela Us JOPT 4 r values measured overwater values if rel Overwater mixing height If overwat available and an actual onshore data set use a value of 250 meters If reasonable to be used use tive humidity if available
13. k is discussed below the stack angle from A vertical s a horizontal s Other angles are possibl the stack height rather is the height of top above the so bu in tion platforms ture above which the stack this sec AQIAGDLS WP5 JUNE 1996 Rev 2 the source ground level for a the water level the vertical is k would have a stack tack would show a e For a is not defined as the tac urce ground level tion is the elevation of the source onshore sources this is level For platforms level of the lowest pla source ground level is with the appropria tform ground the ground elevation above mean sea this is the el level defined above For deck to be specified in feet or me te multiplier indicated for variable evation above mean Sea The elevation of the ters CELM in card type 4 the water i e barges etc the source will be zero 0 As an example of the interrelationship of the parame consider an offshore platform with and 35 meters above the wat ground level would be the eleva All stack heights would be defined t deck described above decks at 15 25 The source lowest deck 15 meters For simple offshore sources in contac crew and supply boats ground level elevation t with construction ELP NPT tankers as heights above the lowest source with a vertica
14. modeling of onshore point sources located in complex terrain with the Rough Terrain Dispersion Model RTDM RTDM is an EPA approved third level screening model 1 Model Description RTDM is designed to estimate ground level concentrations in complex terrain from buoyant plumes The model adjusts the plumes path near hills according to hill top height and the meteorological conditions Plumes may go up and over a hill or impinge upon the terrain depending on the conditions RTDM has many parameters and optional features useful for a wide variety of applications Some of the features incorporated in the RTDM model include a reflection algorithm which limits the reflection of the plume from the ground so that the plume concentration is not allowed to increase downwind from the source a procedure for allowing plume impact below the critical height dividing streamline Plumes above this level will move over a terrain feature It is computed from the wind speed terrain height and strength of the 13 AQIAGDLS WP5 JUNE 1996 Rev 2 inversion an improved plume path correction over terrain to modify the plume height above the ground 2 Applicable Source Types RTDM is applicable to only point sources A maximum of 35 collocated sources with the same stack base can be input into the model The sources may be collocated if they are within 20 meters of one another Sources tha
15. AQIAGDLS WP5 JUNE 1996 Rev 2 to scale concentrations from a single the concentrations from up to 5 input SEQADD is to be run in accordance with the RTDM User s Guide whenever multiple sources are involved but not for collocated sources Vv Modeling Onshore Non Point Sources with ISCST A General Information This section outlines the District guidance for modeling air quality impacts from onshore non point source type emissions volume and area sources designed to be applicable This protocol is specifically to the following types of emission sources 1 Onshore construction combustive emissions NOx PMio SO2 CO a Site preparation and grading b Facility installation and assembly c Pipeline right of way ROW preparation trenching and installation d All other combustive emissions prior to facility operation 2s Onshore construction fugitive emissions PMig a Site preparation and grading b Facility installation s Pipeline ROW preparation and trenching d All other ground disturbing activities 3a Onshore operational gaseous fugitive emissions ROC H2S This category includes fugitive emissions from valves flanges atmosphere 4 TSP PMio connections and any other venting of ROC to the Onshore operational particulate fugitive emissions 20 AQIAGDLS WP5 JUNE 1996 Rev 2 m a Fugitive dust from excavation mine pits stockpi
16. height At a minimum hourly averaged wind speed wind direction stabilit temperature stability class and ty class and temperature are to be obtained from the District approved preconstruction monitoring program for of the overland meteorological parameters and the hierarchy of their use is as follows the proposed project A discussion pie Overland wind direction Not mandatory if overwater wind direction data are available Overland wind directions will be set equal to overwater values for each hour 35 AQIAGDLS WP5 JUNE 1996 Rev 2 ii Overland wind speed Use measured overland values if available derived from overwater value if not available Calm periods in the overland data set are to be handled as follows All wind speeds less than 1 m sec must be converted to 1 m sec prior to input to the OCD model The CRSTER preprocessor which may be utilized deals with calm winds hourly mean wind speed approaching 0 in the following manner Wind speeds less than 1 m sec are set equal to 1 m sec The wind direction is set equal to the value for the last non calm hour iii Overland air temperature Use measured overland values if available iv Overland stability class Use values calculated per the latest USEPA Modeling Guidelines if the necessary data to calculate stability class are available If data is not avail
17. is only app wable increment nt of airg ysis t and reactive addresses inert utant modelin urces Board men Photoch Dis proc are wha appr requ Fumi air CELE modelin edures to be to be used in is 5 in oval Sections Ls fol CARB the anal gu the air qu AQIAGDLS WP5 JUNE 1996 Rev 2 unty Air idance on the use of air ality impacts of nt repres the Author nts an update and of Chapter 6 Air ity to Construct ATC addition t AQIA is ants pol a submi iremen gation ts for SCREEN Section VI II ou New Source Review Depending upon the pollutan A may be required to evalua ty standards tion of ambient air quali th project emissions licable to attainment pollutants for wh levels have been established I presents an introduc g requirements ysis ttal to the District for review and through VI discuss specific model ISCST RTDM tlines qual lity values and o the technical ght under a separate required when applicable ds specified in District rules are exceeded These emission trigger levels are specified in District Rules and fo incremen th attainment and ts to be te compliance with consumption or both r bo An uality degradation in an attainment crement consuming sources must be included in an incremen y
18. mass emissions To determine the mean plume rise from the individual sources in the volume source being modeled the following anticipated reasonable worst case meteorological conditions are to be used F Stability class 1 0 meter second wind speed F Stability class 1 5 meter second wind speed F Stability class 2 0 meter second wind speed For each individual source contained in the volume source the mean of the plume rises associated with the above meteorological conditioned is to be calculated hm Ahi F 1 0 Ah F 1 5 Ahi F 2 0 3 For each individual source contained in the volume source the mean plume rise is to be weighted by the emissions rate of the source in grams second This is to be done by multiplying the mean plume rise by the emission rate on a source by source basis MWPR hm x Qi Sum the products of mean plume rise and emission rate for each of the sources contained in the volume source Sum the emission rates for each of the sources contained in the volume source i 1 To obtain the vertical dimension of a ground based volume source divide the quantities obtained above as follows N 23 AQIAGDLS WP5 JUNE 1996 Rev 2 2 MWPRi If the vertical dimension of the ground based volume source is calculated to be greater than 10 meters the value is to be set equal to 10 meters In no instance is the vertical d
19. reasonable worst case meteorological data maximum modeled concentrations will be representative of one hour averaging periods only Table 7 lists multiplying factors which are to be used to convert the maximum one hour modeled concentrations to concentrations representative of longer averaging periods TABLE 7 Factors to Convert One Hour Modeled Concentrations to Longer Averaging Periods Modeling Result Averaging Multiplying Averaging Period Period Factor 1 hr 3 hr 0 90 1 hr 8 hr 0 70 1 hr 24 hr 0 40 1 hr Annual 0 10 E Shoreline Geometry OCD requires specification of the location of the shoreline relative to source and receptor locations Receptors and sources involved in a given simulation do not necessarily have to be within the area specified by the shoreline geometry grid The shoreline grid is comprised of a number of cells defined in Card Group 15 The user must specify whether each cell is land L or water W The maximum grid cell length horizontal or vertical that should be specified is one half kilometer Horizontal and vertical grid cell lengths do not need to be the same as long as each is less than or equal to one half kilometer It may be necessary to adjust the designation as water or land of individual grid cells to ensure that shoreline receptors are located in a cell specified as land The OCD model prints the grid information so that the us
20. to be determined by the construction activities being simulated b Height of Base of Source Above Surface Relhgt 24 AQIAGDLS WPS JUNE 1996 Rev 2 Specifics of the height of the base of the source above the surface for line sources are equivalent to those for volume sources Cr Initial Vertical Dimension SIGMA Z0 input as TS Specifics of the initial vertical dimensions for line sources are equivalent to those for volume sources d Initial Lateral Dimension SIGMA Y0 input as Syinit The width Xo of adjacent volume sources used to represent a line source is to be less than or equal to 50 meters in all cases In most circumstances the value of X for line sources will be on the order of 20 meters or less The value of the initial lateral dimension SIGMA Y0 is to equal X 2 15 for adjacent volume sources used to represent a line source For a line source represented by separated volume sources of equal width X is center to center distance GH Area Sources AREA Emissions which are to be modeled as area sources include fugitive emissions of PMio TSP ROC and H2S Area sources are characterized by non buoyant emissions containing negligible vertical extent of release Fugitive particulate PM jo TSP emission sources include areas of disturbed ground which may be present during both the construction clearing grading excavating and operational open p
21. 0001 0 004 Fallow field or low grass 0 01 0 03 High grass 0 03 0 10 Sand dunes 0 05 0 10 Flat rural few trees 0 003 0 03 Rural rolling terrain few trees 0 01 0 15 Woods 1 00 Suburban 0 5 1 5 Urban 1 5 4 0 Dense vegetation cover 1 8 of the From Hanna et al 1984 Roughness length increases for tal obstacles to wind flow or for hig The stack height is specified as ground level For onshore so level is the local ground eleva sources in contact with the wate tankers construction barges et source ground level offshore sources that extend abo ELP NPT Roughness length increases with increasing wind speed ler or more closely spaced her terrain obstacles the height above the source urces the source ground tion For simple offshore r crew and supply boats c the water level is the 0 For more complex ve the water on stilts or 3 3 1996 Rev 2 average canopy legs such as drilling or produc ground level is the base s extends For instance the multideck platform would be of the lowest deck non vertical stac The deviation of specified in degrees angle deviation of 0 0 deviation of 90 0 non vertical stack physical length of the center of the the stack tack S The final parameter required truc source the height abov The definition of stack height for a
22. ARAMETER section The model uses default values for these options if the user does not specify them The District recommends specific values to be used for some of these parameters These values are listed below PR001 Horizonal Scale Factor Set HSCALE to the default value 1000 to convert kilometers to meters PROO2 Vertical Scale Factor Set VSCALE to the default value 0 3048 to convert feet to meters PROO3 Wind Speed Scale Factor Set USCALE to 1 0 for wind speeds in m s PR004 Wind Speed Measurement Factors 15 AQIAGDLS WP5 JUNE 1996 Rev 2 Set ZWIND1 to the anemometer height for winds used in the meteorological data file ZWIND2 is not to be used set to 10 set IDILUT to 0 to use winds at stack top height ZA is th ffective displacement of the meteorological tower base above the stack base elevation m usually 0 0 PROO5 Wind Profile Exponents Use th ither of the following wind profile exponents depending on urban or rural environment Urban 0 10 0 15 0 20 0 25 0 30 0 30 Rural 0 07 wOeO7 0 10 0 757 0 35 0 55 PROO6 Dispersion Parameters Set ICOEF to 2 to use the Pasquill Gifford option PR007 and PROO8 Crossover Distances for ASME Do not use this option Not applicable for Pasquill Gifford dispersion PROO9 Partial Penetration of Elevated Inversion Do not use this option PR010 Buoyancy Enhanc
23. Emissions TSP PMio Those emissions which are independent of the operational schedule of the facility are to be modeled in the same manner as fugitive ROC in 2 a above This may include fugitive dust from stockpiles excavations graded areas etc Emissions which are dependent upon facility operation such as those from conveyors crushers etc are to be modeled in the manner of the construction emissions discussed above Fi Meteorology 28 AQIAGDLS WP5 JUNE 1996 Rev 2 Meteorology is the same as that presented for ISCST point source modeling in Section III D VI Modeling Offshore and Associated Coastal Source Emissions A General Information This section outlines the District guidelines for modeling inert pollutant air quality impacts from offshore sources and coastal 1 e within 1 km point sources which are directly associated with offshore sources of air emissions The air quality model presented in this section is OCD which may be used for sources in these situations The OCD model is to be used for all inert pollutants and all averaging periods OCD is available on a floppy disk tape from the District Ts Model Description The Offshore and Coastal Dispersion OCD model Version 4 0 was developed by the Minerals Management Service MMS and approved by the U S Environmental Protection Agency s EPA OCD is an hourly steady state gaussian model developed to determine impacts
24. Santa Barbara County Air Pollution Control District MODELING GUIDELINES FOR AIR QUALITY IMPACT ANALYSIS Santa Barbara County Air Pollution Control District MODELING GUIDELINES FOR AIR QUALITY IMPACT ANALYSIS June 1996 MODELING GUIDELINES FOR AIR QUALITY IMPACT ANALYSIS SANTA BARBARA COUNTY AIR POLLUTION CONTROL DISTRICT 26 Castilian Drive B 23 Goleta California 93117 805 961 8800 June 1996 TABLE OF CONTENTS Abbreviations and Acronyms OVERVIEW H H H ADAWPH QW PH a uj Q ADAWPH Introduction General Procedures Source Parameters Models Source of Models Submittals to the District Screening Analysis General Information SCREEN Averaging Time Conversions Modeling Point Sources with ISCST General Information Point Sources in Simple Intermediate or Complex Terrain Building Downwash Considerations Modeling Onshore Point Sources with RTDM General Information Model Inputs RTDM Options Running RTDM Postprocessor Analysis Modeling Onshore Non Point Sources with ISCST General Information ISCST Options JUQUWZ lt ISCST Modeling of Volume Line and Area Source Types Scheduling and Averaging Period Considerations Meteorology Modeling Offshore and Associated Coastal Source Emissions General Information OCD Model Input Requirements Point Source Description Information Meteorology Shoreline Geometry
25. TPUT OPTIONS Source Type 0 Point Source 1 Area Source 2 Line Source CREATE summary output file called EXTRA OUT Write hourly concentrations to disk or tape Filename is CONC BIN CREATE table of annual impact assessment from 0 non permanent activities Land Source Do Not Modify Wind Speed Specify pollutant decay rate via chemical 0 transformation 32 The width and height the stack location downwash effect AQIAGDLS WP5 JUNE t of the building or obstacle at or near that exerts primary influence on building ts must be specified In many cases this will be the building to which the stack is attached However attached should be height of the building with the should be used For an offshore will be the height of the tall on the top deck of the plat above the source is defined below calculat tform ground level TABLE 4 Ground Covers if a nearby building or other solid struct larger dimensions than the building the Good Engineering Prac ted for each buil ture has to which the stack is tice GEP stack height ding and the width and higher GEP stack height platform this parameter lest solid structure or section specified as the height The source ground level Typical Surface Roughness Lengths for Various SURFACE ROUGHNESS GROUND COVER LENGTHS meters Water surface 0 0
26. a scal potential construction activii method presented in Section D 1 and apply a scaler va e annual average concentration from construction ac to occur for less than a to be calculated by multiplying the average concentra mber of days of meteorology modeled the keyword AVERTIME under the Source by the number of days in the construct calculated by construction monitoring scheduling method Ls a PCM ter Qflag in the keyword the keyword EMISFACT ler value of ty as determined 0 for ue of tivi one year period is tion for the using the tion period ties as determined by the scheduling method presented in l a and dividing by 365 27 AQIAGDLS WP5 JUNE 1996 Rev 2 In some instances there may be several distinct construction activities occurring at a single site during a one year period which are conditioned to not occur simultaneously In these instances each construction activity is to be analyzed with the schedule determined per the scheduling methodology presented in Section D l a Should separate construction activity analyses overlap due to consideration of the one month period preceding and following the conditioned activity then the analyses are to be performed separately with the period of time beyond the period of conditioned activity being split equally so as to not result in modeled overlap between scenarios Short term less than or equal to 24 hour
27. able to calculate hourly stability class the applicant must use the reasonable worst case meteorology Table 6 for all the overland and overwater parameters v Overland mixing height Twice daily mixing heights are available from Point Mugu and Vandenberg If unavailable hourly mixing heights can be estimated from Holzworth 1972 b Additional meteorological data The additional meteorological data set contains overwater meteorological parameters and overland turbulence intensity values The user can indicate whether a particular parameter is provided or is not provided or not to be used by specifying options JOPT 1 through JOPT 9 in card type 13 of the OCD input list In all instances the period of record for the additional meteorological data set is to be identical to the overland meteorological data set A complete set of additional meteorological data includes hourly averages of the parameters listed and discussed in 36 Section D 1 b 1 actual overwater data se subject to the considera data set to be filled in hierarchy 1 Overwater wind F t approved actual direction Us JOPT 1 1 being used for all sources measured overwater values ta set if available This will result in offshore wind directions both offshore and onshore If overwater and overland values are not available AQIAGDLS WPS JUNE 1996
28. above water vel of overwater anemometer HWT Height above water V of overwater air 40 0 or 0 or Rev 2 b 2 0E 3 Leor 2 Q or 1 AQIAGDLS WP5 JUNE 1996 Rev 2 TABLE 6 Reasonable Worst Case Meteorological Data Set for OCD Simulations Parameter Overwater Wind Direction WD Wind Speed WS Mixing Height HLW Relative Humidity WHUM Air Temperature WTA Air to Sea Surface WTS Temperature Difference Wind Direction Shear WDSHR Overwater Horizontal LYW Turbulence Intensity Overwater Vertical IZW Turbulence Intensity Overland Horizontal IYL Turbulence Intensity Overland Vertical IZL Turbulence Intensity Vertical Temperature Gradient WDTHDZ Overland Wind Direction QTHETA Wind Speed QU Mixing Height QHL Input value Applicable sector of wind directions in one degree increments 1 0 m sec Height to result in highest modeled impacts or 100 to 300 m in 50 m increments 90 percent 290 K 2 00 K 2999719 0 045 0 020 999 9 999 9 0 050 K m Same directions as used for overwater data set 1 0 m sec Same mixing heights as used for overwater data set 41 Stability Class Air Temperature IKST QTEMP AQIAGDLS WP5 JUNE 1996 Rev 2 6 Stability Class F 290 K 42 AQIAGDLS WP5 JUNE 1996 Rev 2 When utilizing
29. concentrations thm and the complex terrain the two concentrations for terrain height is equal or exceeds the plume height then terrain for that hour and receptor ISCST calcula terrain screen ing algorithm on B Point Sou rces in Simple that source tes concentrat Intermediate that terrain is defined as COMPLEX For a complex terrain tions based on the complex Ly or Complex Terrain This section discusses the values to be specified for each control option used by ISCST the specifications are for ISCST version 93250 the most up to date version at th time these guidelines were published ISCST Control Option Specifications Keyword Parameter MODELOPT CONC RURAL or URBAN GRDRIS NOBID NOCALM AVERTIME 1 3 8 24 PERIOD POLLUTID SO2 NOX CO PM10 TSP or OTHER HALFLIFE Do not use DECAYCOEF Do not use TERRHGTS FLAT or ELEV FLAGPOLE Do not use EVENTFIL Do note use SAVEFILE Do not use INITFILE Do not use MULTYEAR Do not use ERRORFIL optional Cs Building Downwash Considerations 1 Downwash Assessment The entrainment of a plume in the wake of a building can result in the downwash of the plume to the ground This effect can increase the maximum groundlevel concentration downwind of the source Because of this each source must be evaluated to 10 AQIAGDLS WP5 JUNE 1996 Rev 2
30. ct the District for a copy of the AQIAGDLS WP5 JUNE 1996 Rev 2 ter vertical potential temperature gradient f ze E use of reasonable worst case meteorology is required then the user is to prepare an hourly data set as specified in Table 6 of this manual d be assessed for each District has created an l assemb TABLE 5 Simulations Option codes 0 AQIAGDLS WPS JUNE 1996 Additional Meteorological Data Options for OCD not provided or do not use temperature sensor 1 provided unless otherwise specified Option Description Option Specification JOPT 1 Overwater wind direction provided JOPT 2 Overwater wind speed provided JOPT 3 Overwater vertical potential temperature data K m are provided JOPT 4 Overwater humidity specified as follows 1 relative humidity is provided 2 wet bulb temperature K is provided 3 dew point temperature K is provided JOPT 5 Overland horizontal and vertical turbulence intensity data is provided JOPT 6 Water surface temperature specified as follows 1 water surface temperature K is provided 2 air minus water temperature K is provided JOPT 7 Overwater wind direction shear degrees m is provided JOPT 8 Overwater horizontal turbulence intensity data O or 1 is provided JOPT 9 Overwater vertical turbulence intensity data is provided HWANE Height
31. d run can be made using the results Any necessary changes e q increasing or decreasing the receptor density changing options must be made in consultation with the District before executing the refined run A full year of on site meteorological data approved by the District will be required for the refined model run E Postprocessor Analysis Post Processing is performed after a refined run has been successfully executed The concentration file generated by the refined run is stored on a disk and then used in post processing The District requires the following three types of post processing analyses i TOPVAL Using TOPVAL concentration for different averaging time periods for each receptor can be calculated The applicant must use the following values for the variables under TOPVAL NH 1 NM 5 NR Number of receptors RFACT 1000000 Do not use values for DAYSIN and HOURSIN TOPVAL is to be set to 1 3 8 and 24 corresponding to 1 hour 3 hour 8 hour and 24 hour time averaging periods respectively and depending on the pollutant analyzed AB PEAK PEAK is used to determine the number of occurrences of exceedances concentrations exceeding a specified value i e air quality standard at each receptor PEAK is to be run in conjunction with each TOPVAL run 19 2 SEQADD The SEQADD keyword is used concen files tration file or add to create a new file
32. day the construction activities are to occur Should the scheduling of a particular construction scenario be unknown or should permit conditions limiting periods of construction not be in effect the construction combustive activities are to be modeled as occurring 24 hours a day 365 days a year As an alternative an applicant may agree to operating limitations to construct for specific hours of the day and or periods of the year In order to provide a degree of potential construction scheduling 26 flexibility to an applicant a one hour period bol 1 the projected hours of construct for proposed construction ac a one month period bot ted period of constr sed construction activities longer following Likewi months in following For prop duration the proje th ntir se duration the projec O a minimum two month period As an exa occur fro modeled a e period to be analyzed is mple m 0700 s 0600 through 1700 local through cted period of construction is tion is both not This is equivalent to model input hours 7 input hou important local sta is based construct meteorolo b r 7 equaling the interval to model ndard on this time scheme gical data from the period Modeling Methodology and Averagin from 0600 all construction activities consis time as th
33. e Longer periods of missing data may be filled in with actual data from another site s which the District has approved as representative Data from offshore sites can not be used to substitute for missing data from onshore sites although with District approval data from onshore sites may be substituted for data from an ther representative offshore site is offshore site if no available Applicants will be required to collect and have validated by the District at least one year of air quality and meteorological data prior to the District considering the project application as complete The overwater reasonable worst case meteorological data specified in Table 6 are to be used in lieu of actual data when the actual data are missing for extended periods when the data have not been collected according to the Districts monitoring protocol or if the data are deemed unacceptable by the District Tg Meteorological Data Set Considerations This section presents the meteorological data sets which can be utilized by OCD Me required by OCD to sa teorological input parameters tisfy District requirements are discussed with respec to the hierarchy and manner in which these data are to be input to the model a Overland Meteorology Overland meteorological parameters required by OCD are wind speed wind direction mixing
34. e meteorological da To continue ion activities which are projected February through 1 August are to be an 1 tivi uction is than through 18 to 0 alyzed usin December th ta in his example to occur from 1 700 AQIAGDLS WP5 JUNE 1996 Rev 2 th preceding and to be analyzed ties less than three th preceding and to be analyzed three months in preceding and following to be analyzed to exceed on However year construction activities which are projected to standard time are 1800 in the air quali to be ty impact analysis with model It is put g the ro tent into with TSEST ugh 1 October g Period Considerations Modeling air quality impacts for all averaging periods from construction combustive emissions occu rring during specific hours of the day or periods of the year can be accomplished in the following mete pres EMI unde all manner U orological data determined tilize the period of pre th ented in Section D l a Specify HROFDY for the paramet SFACT under the Source pat For the parameter Ofact per thway in r the Sou hours of rce pathway input per exa 0 0 Th which are nu parameter pathway analyzed Section D the scheduling mple Hours 7 through 18 for all remaining hours conditioned PERIOD in L
35. ect being modeled has a combination of different source types e g multiple sources several runs should be executed and the impacts summed For cases where there ar differing technical considerations e g building downwash versus complex terrain both issues should be assessed with the highest results used It may be necessary to run SCREEN several times to account for all these different scenarios he building downwash option should be selected if there is a ilding within a distance of 5L where L is the lesser of ilding height or maximum projected building width from the urce Input the building parameters accordingly i e ilding height length and width in meters In case of more a e b i g O han one nearby buildings within a distance of 5L select the uilding with the highest GEP stack height to cal cence the building downwash effects The GEP stack height Hg is calculated as follows OCOUOOCH Hg H 1 5 1 where H building height in meters and L lesser of building height or maximum building width in meters For a scenario with complex terrain and building downwash first run SCREEN using the complex terrain option Then independently run SCREEN using the simple terrain option with building downwash and setting receptor elevations at the stack top level The highest value from the two runs should be selected as
36. ed Dispersion Set IBUOY to 1 to use buoyancy enhanced dispersion and set the constant ALPHA to 3 162 PR011 Unlimited Mixing Height Stable Conditions Set IDMX to 1 to use unlimited mixing height for stable conditions PRO12 Transitional Plume Rise Set ITRANS to 1 to use transitional plume rise PRO13 Plume Path Correction Factors Use the RTDM default values 6 0 5 The RTDM code adjusts these factors to zero for stability classes 5 and 6 when the plume path is below the critical height PR014 Default Potential Temperature Gradients 16 AQIAGDLS WP5 JUNE 1996 Rev 2 Use the RTDM default values 0 02 and 0 035 K m PR015 Stack Tip Downwash Set ITIPD to 1 to use stack tip downwash PRO16 Hourly Turbulence Intensity Data Sigma y Do not use this option PRO17 Hourly Turbulence Intensity Data Sigma z Do not use this option PRO18 Hourly VPTG data for plume rise Do not use this option PRO19 Hourly VPTG data for H crit Do not use this option PRO20 Hourly Wind Shear for Sigma y Do not use this option PRO21 Hourly Wind Speed Profile Exponents Do not use this option PRO22 Partial Reflection Algorithm Set IREFL to 1 to use the partial reflection algorithm PRO23 Horizontal Distribution Function Set IHORIZ to 1 to use the off centerline horizontal distribution function PRO24 Hourly S
37. emissions from operating at permitted used for modeling Annual average average concentration ust be reviewed by uting the model m the models which are to be For all inert pollutant screening analyses pollutant impacts from all LO terrain with elevation the lowest stack height model inert pollutant impacts from onshore non point emission sources and line sources e g RTDM lowest area volume For modeling inert pollutant onshore point sources which impact t elevation equal to or greater than stack height impacts from all terrain with the height of the OCE of emissions For modeling inert pollut offshore sources and coast km from shoreline associ ated wit tal point sources AQIAGDLS WP5 JUNE 1996 Rev 2 tant impacts from up to 1 th offshore sources Table 1 provides some generic project scenarios and the associated modeling requirements For refined analyses ther ISCST or RTDM performed with SCREEN sources require the use of i terrain processing plant onshore activities will modeling will be executed for A ISCST all po onshore construction activities For onshore sources ISCST will automatically sum the hourly must be noted thin one kilomet onshore cons and summed with all In addition Screening analyses can be onshore point that
38. er can check the distribution of land and water features The minimum along wind width for a land or water body to be considered significant should be set equal to the smaller of the horizontal and vertical grid cell lengths VII Fumigation Modeling Fumigation occurs when a plume is emitted into a stable layer of 43 AQIAGDLS WP5 JUNE 1996 Rev 2 mixed to the ground through Fumigation may usually high concentrations over short time periods ion may also occur on and near the shoreline when a stable due to convective transfer of air and that layer is subsequently convective transfer of heat from the surface cause un Fumigat plume overwater traverses overland to unstable conditions resulting in rapid downward mixing heat from the surface For onshore sources concentrations due to fumigation l handles fumigation internally based on overwater and overland stability differences Also the California Air Resou to the Cal mode aval document titled Board Air Quality Modeling Section the ARB wh fumigation models umigation impacts from tape containin 1984 test EOT VIII To assess one is for assessing ARB will send a magnetic those requesting it for a handling fee also available from the District lable from Users Guide is available free from cases for two further guidance For o
39. evel or utili measured Reasonable Worst Case Meteorological Da The adequacy of any overwater or overland me da me sec must OCD Table 6 If the ta set wil case by case basis teorological data with of OCD modeling tions VI D l a t utilize reasonable worst case me The reasonabl Le wors likely on coastal terrain examined in initial will result in reasonable worst case meteorology is being used of the OCD User s Man lection of offshore meteorological ual for ta teorological l be determined by District staff on a The applicant should review proposed If certain da and VI D 1 b are no including all the District prior ta req uiremen to commencemen ts listed in met teorolo t case data set is presen win the analysis gy as input to ted in d directions to produce maximum impac ts from the proposed projeci A variety of mixing heights should be model runs to determin the highest modeled impacts the height that Equivalent overland and overwater mixing heights from 100 to 300 meters in wind direc in 50 meter incremen tion modeled teractive FORTRAN program The that wil tse shoul le an appropriate data set when reasonable worst case me Po program 39 teorological data are required for all parameters tential users may conta
40. ffshore sources Please the SCREEN model can be used to assess the OCD Fumigation models are rces Board CARB A ifornia Air Resources Fumigation Models Wagner ich lists the codes and The Fumigation Model code onshore sources The this fumigation model to Fumigation models are contact District staff g Background Air Quality Ozone Limiting Method three and eight h our background air quality values for construction activities which occur for only a portion of the day of construction activities wh model the port mode are cons air cons appl A us ich construction activities which use the observed backgrou the year during which year ion of led to be selected from the portion truction activities were model the observed background air quality only for were modeled construction activities Twenty four hour average background air quality values quality values are to be obtain truction ambien icant Use of Background Air Quality the hours Likewise to occur for only a portion of nd air quality only for the were of the year during which the d Annual average background ed from the year of pre air quality monitoring data collected by the for Pollutants Other Than NO The values for background air quality for pollutants requiring modeling must be accomplished in phase of the project prio
41. from offshore point area or line sources on the air quality of coastal regions It consists of three major subroutines namely the overwater subroutines based on overwater boundary layer dynamics the overland subroutines based on the MPTER model used for dispersion over a flat to rolling terrain and the subroutines based on RTDM model to consider dispersion in complex terrain receptors above stacktop elevation OCD accounts for the change in plume dispersion during transition from the overwater to overland environment by means of a virtual point source treatment OCD can handle both offshore and onshore sources in the same model run For onshore sources OCD reduces to either the MPTER or RTDM calculations for receptors below or above stacktop elevation respectively VE Applicable Source Types The OCD model is applicable to coastal projects which include offshore sources of air emissions For example an oil development project that included emissions from one or more offshore platforms associated mobile sources such as tankers or supply boats and coastal processing facilities would use the OCD model for all offshore emissions and for all onshore point source emissions within one kilometer of the coastline Offshore mobile sources such as vessels and barges can be simulated as a line source with OCD or as a series of point sources covering the 29 AQIAGDLS WP5
42. hniques writt short ten into FORTRAN code t term concentrations for single sources AQIAGDLS WP5 JUNE 1996 Rev 2 The techniques are used to calculate interactive and is relatively user friendly 25 Options The model is SCREEN can be used to assess air quality impacts from each of the scenarios listed above All required data available options are summarized below a Source parameters S pollutant emission rat stack height m stack inside diameter stack gas exit velocit tacks te g s m ty m S stack gas exit temperature K ambient air temperature K use 290 Source parameters Area Sources emission rate g s release height m length of side m Building downwash building height m minimum horizontal building width m maximum horizontal building width m Complex terrain terrain height m distance to terrain m Meteorology full meteorology input single stability class input single stability class and wind speed urban or rural 1 or 2 Receptors discrete distance minimum distance maximum distance m m m flagpole height m m m 3h Discussion including units and AQIAGDLS WP5 JUNE 1996 Rev 2 It is very important to examine both the geographical location and the project components before implementing these procedures If the proj
43. ify JOPT 9 0 so that model default calculations are used Actual data should not be used because of measurement limitations overwater If the reasonable worst case meteorological data has been specified as a priority above the value in Table 6 applies for all hours TX Overland turbulence intensities Overland horizontal and vertical turbulence intensities IYL and IZL respectively are not to be used as direct input to OCD Utilize a value of 999 9 for this parameter which indicates that overland turbulence intensities will not be 38 used horizon calcula and used as input X Table 5 The heig these in 1 e Please refer further direc data Ez S h S Specify JOPT 5 as 0 in all si tuations Overwa In all instances used for all hours t of th sensor must also be provided JOPT 3 ta set the value specified in Table 6 Overland tal vertical turbulence intensities can be used to te stability classifications per District procedures in the overland da is to be is to be specified as 1 ummarizes the additional meteorological data options which can be used in the OCD simulat randa to Volume overwa tion on col ter anemomet Specify the actual height o truments in meters abov a value of 10 meters if th water these parameters are not ions ir temperature l
44. imension of a volume source to exceed 10 meters The initial vertical dimension SIGMA Z0 for a ground based volume source is then equal to the vertical dimension of the source specified by the user divided by 2 15 ii Operational Fugitive Emissions The initial vertical dimension SIGMA Z0 of the volume source representing operational fugitive emissions is to be equal to the vertical extent of the fugitive emitting sources not to exceed 10 meters divided by 2 15 d Initial Lateral Dimension SIGMA YO input as Syinit Rather than model construction emissions or other volume sources as one large volume source the emissions are to be modeled as a number of smaller volume sources The width of a volume source Xo is to be less than or equal to 50 meters in all cases The value of the initial lateral dimension SIGMA Y0 is to be equal to Xo 4 3 Des Line Sources Emissions resulting from construction combustive activities which occur in a relatively narrow corridor such as pipeline trenching pipeline ROW preparation and pipe handling are to be modeled as line sources Line sources are represented by a series of adjacent volume sources the number of volume sources N being equal to the length width of the line source a Emission Rate Specifics of line source emission rates are equivalent to those for volume sources The distribution of emissions along the line source is
45. in elevation of source above mean sea level height of source of emissions above ground surface initial vertical dimension volume and area sources only and initial horizontal dimension volume sources only Specific information on the appropriate source parameters is discussed in this section Ty Volume Sources Srctyp VOLUME As a rule sources with emissions containing an initial vertical extent are to be modeled as volume sources The initial vertical extent may be due to plume rise or a vertical distribution of numerous smaller sources over a given area Emissions which are to be modeled as volume sources include those 21 AQIAGDLS WP5 JUNE 1996 Rev 2 resulting from construction combustive activities NOx PMio SO2 CO and operational fugitive emissions ROC H2S TSP PMio which emanate from numerous levels covering the same ground surface area a Emission Rate Vlemis The emission rate for volume source emissions is to be specified in grams second g s The worst case one hour emission rate is to be used for all averaging periods except for annual average which will utilize an annual average emission rate All emission rates are to be calculated in a manner consistent with District approved procedures With respect to modeling combustive PM emissions the following PMi9 TSP ratios are to be used in the absence of more specific information CARB 1987
46. ing analysis is intended to provide a conservative estimate of the impacts from stationary sources to ascertain whether the potential for an air quality problem exists The procedures are intended to be quick and inexpensive Because of these factors there are many limitations to the application of screening procedures Highly complex projects e g multiple stacks differing source types can not be assessed using these simple procedures If a screening procedure reveals the potential for an air quality problem a refined analysis must be undertaken I Applicable Source Types The screening techniques presented in this section apply primarily to continuous steady state releases which are neutral or positively buoyant For screening purposes intermittent sources should be considered continuous and modeled using the worst case l hour emission rate The following list summarizes the source types for which screening is applicable onshore point sources in simple or complex terrain onshore point sources with or without building downwash onshore area and volume sources The procedures in the SCREEN model can estimate concentrations for each of the above source types The PTPLU model can only be used to assess point sources without downwash in simple terrain These models are discussed further below B SCREEN l Model Description The SCREEN model consists of several simple screening tec
47. iscussed in this document All emissions from the stationary source being analyzed are to be included in the AQIA This includes facilities in the Outer Continental Shelf OCS and outside of Santa Barbara County which have the potential to impact Santa Barbara County air quality and all facilities within the jurisdiction of the District In addition the AQIA may be expanded if project conditions placed on the applicant by other regulatory agencies direct that other scenarios be examined by the District Examples of additional issues for which analysis may be required include but may not be limited to Air quality impacts from consolidated facilities Cumulative air quality impacts from proposed project and all reasonably foreseeable projects Air quality impacts from construction emissions Future specific throughput rates or levels of production not applied for by the applicant Air quality modeling is extremely source specific Complex source configurations may requir xtensive modeling procedures which would not be needed to assess a simple source Because of this the District recommends that a modeling protocol be submitted for all projects prior to executing the models The protocol must contain all relevant modeling information including the specific model to be executed program control data source parameters receptor data and meteorological data All proced
48. istance array or to examine discrete distances one at a time The 46 automated distance array requires th specificat intervals are set every AQIAGDLS WP5 JUNE 1996 Rev 2 tion of both a to 50 000 meters minimum and maximum distance ranging from 100 The model then automates intervals in the following manner from 100 to 3 000 meters interval meters from 3 000 to 10 000 meters 500 meters From 10 000 to 50 000 meters 5 000 meters The model then calc Discrete input complex This opi sensitive receptors the distance array is helpfu potential air quality the discrete distance represent height receptors only requ tion is usefu EL Gw lates concentrations al problems schools ts the closest terrain point When using SCREEN it requirements listed above under consideration Qi The general is important ISCST ire that the distance of interest l in assessing concent and must be used terrain impacts When analyzing complex should be set in such a manner t each distance l for determining the distances to trations at to assess terrain impacts ler spacing that it t that is at or above plume to keep the general requirements regarding receptor grid spacing discussed in Section IX A should be fo ISCST Additional receptors with a smal
49. its unpaved roads parking lots phases of a facility s life Also included are areas of exposed material storage stockpiles and segments of material transport where potential fugitive emissions may occur uncovered haul trucks or rail cars emissions from unpaved roads Fugitive emissions may also occur during stages of material handling where particulate material is exposed to the atmosphere uncovered conveyors hoppers and crushers Fugitive hydrocarbon emissions emanating from a specific level are to be modeled as area sources This may include fugitive emissions from valves flanges venting and other connections which occur at ground level or at an elevated level or deck if on a building or structure Sources of fugitive gaseous emissions with a vertical extent greater than one meter are to be modeled as volume sources a Emission Rate Aremis 25 AQIAGDLS WP5 JUNE 1996 Rev 2 The emission rate for area sources is to be specified in grams per second square meter g m s The worst case one hour emission rate is to be used for all averaging periods except for annual average which will utilize an annual average emission rate All emission rates are to be calculated in a manner consistent with District approved procedures With respect to modeling fugitive PM emissions a PMio TSP ratio of 0 64 is to be used in the absence of specific information CARB 1987
50. l and was located on the secon 15 2 12 meters for th stack that was two d deck would e stacl ters three er surface the tion of For instance a diesel 2 meters tall have a value of t A flare boom 25 k heigh with a length of 20 meters th at a 45 degree angle would h sin 45 degrees x 20 34 obstacle influencing downwash largest solid structure exten example a three 3 meter h would be specified as a heigh level of 15 meters that is D Meteorology at ex ave a 14 me stack h tended from the top deck eight of 35 T5 ters would be th ding abov igh encl The height of the e height of the the upper deck For osure on the upper deck t above the source ground 33 15 3 23 meters As the OCD model is to be applied to offshore sources and coastal point sources associated with offshore facilities both overland and overwater meteorology are required inputs 34 AQIAGDLS WP5 JUNE 1996 Rev 2 Overland and overwater preconstruction monitoring data sets to be used as input to OCD must be of at least one year duration with a minimum 90 percent approved data capture rate The following procedure may be used to fill in the data set to 100 capture Generally short periods of one to six hours may be interpolated with District approval from data at the same sit
51. les and graded areas b Fugitive dust from unpaved roadways and parking lots Ti op Fugitive dust from material transport such as uncovered haul trucks railways d Fugitive dust from material handling such as uncovered conveyors crushers hoppers screens etc This protocol is designed to cover the majority of scenarios which are anticipated to be analyzed by the District However should a particular scenario include components which are not covered in this protocol the District will determine th appropriate procedures to be used in the Air Quality Impact Analysis By ISCST Options The option specifications for non point sources are the same as those presented for point sources in Section III B 1 These specifications should be used for submittal to the District Should the applicant wish to employ option specifications other than those listed above which do not affect the concentration calculations they may do so with proper notification to the District prior to making the modeling runs Ca ISCST Modeling of Volume Line and Area Source Types ISCST has the ability to simulate four source types point stack area volume and open pit This section discusses the treatment of non point source emissions types For each source the following parameters are required as input emission rate coordinates UTM or relative to user orig
52. monitoring SBCAPCD 1990 It is important to note that the the wind is blowing must be reversed 180 degrees to conform with the average flow vector the direction toward which the wind is blowing Stability class is to be obtained in a manner consistent with EPA document Guideline on Revised July 1986 USEPA 1986 Twice daily mixing heights are available from Point Mugu and Vandenberg If unavailable hourly mixing heights can be estimated from Holzworth 1972 Air Quality Models db Calm Scenarios a All wind speeds less m sec prior to input b The CRSTER preprocessor than 1 m sec must be converted to 1 to the ISCST model which may be utilized deals with calm winds hourly mean wind speed approaching 0 in the following manner wind speeds less than 1 m sec are set equal to 1 m sec the wind direction is set equal to the value for the last non calm hour The meteorological shown in Table 2 TABLE 2 Variable data file must use th Fortran e default ASCII format as Meteorological Data Format Format Columns 12 AQIAGDLS WP5 JUNE 1996 Rev 2 C KE ORA OE WA igits I2 I2 I2 I2 Ambient Temperature K A 1 B 2 F 6 IV Modeling Onshore Point Sources with RTDM A General Information This section outlines District requirements for inert pollutant
53. on California Air Resources Board December 1984 50 AQIAGDLS WP5 JUNE 1996 Rev 2 H TSD DOCS AQIAGLDS WP5 51
54. ources produced from a single source or a receptors should be placed onshore at degree radials centered on the source or If sources are more widely spaced a cartesian grid of receptors will be necessary to calculate maximum impacts This cartesian grid should comply with the general requirements outlined above Receptors for offshore source simulations should begin at the shoreline and continue as far inland as necessary to cover the area s of maximum impact X Modeling of Emission Reduction Credits Offsets To the extent the source s t possible offsets will be included in the AQIA I to be used as offsets was operating during the air quality preconstruction monitoring period then the contribution of the offset t source s to the background air quality values used in the AQIA may be considered for being backed out of the appropriate air quality background value Backing out is to be considered only if it can be determined that the offset source s impacted the air qualit ty monit tor s during the time period when the background air quality value s used in the AQIA were measured Contact If the source s Dis trict s taff for guidance on this matter to be used as offsets were modified so as to implement an emissions reduction strategy during the year of preconstruction monitoring for air quality then no further consideration on
55. r The refined run is to be made with a more detailed receptor set in the vicinity of those areas where high concentrations are expected The initial receptors are to be constructed at 250 meter intervals on a cartesian grid centered near the source with additional receptors placed every 100 meters apart around the facility boundary No receptors are required within the property It is important that the procedure used to select the height and location of receptors is consistent with that used for obtaining the terrain profiles The locations are to be in UTM coordinates km and the elevations are to be in feet a Preliminary Run This run is very useful to confirm whether all the proper options have been used as well as providing an indication of the highest 18 AQIAGDLS WP5 JUNE 1996 Rev 2 impacts and locations This allows the user to properly design the receptor grid e g increase or decrease the density of the receptors The preliminary run is to be made using a meteorological data set consisting of 36 wind directions one every 10 degrees from 10 to 360 degrees with wind speeds set to 1 m s mixing heights at 500 meters stability class 6 and temperature 65 F Source and terrain inputs are to be specified as outlined in Sections IV B 1 and IV B 2 parameter options are given in Section IV C 1 DY Refined Run After the preliminary run is made a refine
56. r Second MMS Minerals Management Servic MPTER Multiple Point Guassian Dispersion Algorithm with Optional Terrain Adjustment NTIS National Technical Information Service NSR New Source Review OCD Offshore and Coastal Dispersion Model OCS Outer Continental Shelf ppm Parts Per Million PTFUM A Single Source Fumigation Model PSD Prevention of Significant Deterioration ROW Right of Way RTDM Rough Terrain Dispersion Model SCREEN Screening Procedures for Stationary Sources UNAMAP User s Network for Applied Modeling of Air Pollution This Poll disp stat evi evi tan document presen ution Control Di ersion modeling ionary sources sion to the Oc ty Impact t Processing Ma sions d alone cover ts the strict to asse The do tober 20 Analysis nual OVERVIEW Cu SS cu from In rrent Santa Barbara Co District m 1987 version the guidelines have been brou An Air Quality Impact Analysis emis Regu nona asse ambi For Cali Thes conj anal sions threshol lations i e ttainment pollut ssed an AQI ent air qual the evalua fornia and e analyses unction wi Li Na musi allo amou in anal Air dispersion models generall Inert pol le reactive iner Gaussian assumptions whil are simulated with Lagrangian or E lutant model g can be obtained documen emical Modeling only poll Reso Docu Sec tion ysis
57. r to performing the AQI air quality values will be added comparison to ambient air quality standards quality is Using data as input to the model d the preconstruction monitoring A Background to project impacts for Background air to be added to project impacts as follows the year of preconstruction monitoring meteorological termine the maximum modeled concentration for each pollutant and averaging period in 44 AQIAGDLS WP5 JUNE 1996 Rev 2 question Review the year of preconstruction monitoring air quality data to determine the maximum ambient air quality values measured for each pollutant and averaging period in question For each pollutant and averaging period add the results of the previous steps to obtain the total pollutant concentration which is to be compared with ambient air quality standards B Use of Background Air Quality for NO2 The ozone limiting method should be applied as follows to convert one hour modeled NO concentrations to NOs concentrations Cole and Summerhays 1979 Using a minimum of one year of most recently available District approved and site representative meteorological data as input to the model determine the maximum one hour NO concentrations NOXMAX Using a minimum of one year to a maximum of three years all data in the maximum required three year period must be used if available of air q
58. rections Each meteorological condition will have a wind speed of 1 m s mixing height of 500 m stability class 6 and temperature of 65F This worst case 14 AQIAGDLS WP5 JUNE 1996 Rev 2 meteorological data set is to be used with the preliminary run of RTDM to determine the high impact areas The second meteorological data set is to be used with the refined run of RTDM to perform a more detailed impact analysis This data set will consist of site specific hourly observed values of wind direction wind speed mixing height stability class and ambient temperature Missing values must be specified as 999 in the input file The initial persistent values to be used in case a value for any meteorological parameter missing in the first hour to be used in the EXECUTE section must be approved by the District before making any RTDM runs Cx RTDM Options The RTDM input run stream consists of five main components Each component or section consists of a group of input data defining the RTDM run These input data sections are preceded by the corresponding keyword and are stacked in the following order PARAMETERS STACKS POINTS TERRAIN c EXECUTE Each input data section is concluded with a line containing 9999 in columns 1 5 1 PARAMETERS Keyword RTDM has 25 parameter options available under the P
59. s Option Description Option Specification Ignore Option 1 Use Option IOPT 1 Use terrain adjustments 1 IOPT 2 DO NOT use stack tip downwash 0 IOPT 3 Do NOT use gradual plume rise 0 IOPT 4 Use buoyancy induced dispersion 1 IOPT 5 Overland meteorological data 0 or 1 0 formatted 1 unformatted filename is LMET DAT IOPT 6 Read hourly emissions Filename is EMIS DAT 0 IOPT 7 Specify significant sources 0 IOPT 8 Read radial distances to generate polar 0 coordinate receptors PRINTED OUTPUT OPTIONS IOPT 9 Delete emissions with height table IOPT 10 Delete met data summary for avg period IOPT 11 Delete hourly contributions 31 IOPT 12 IOPT 13 IOPT 14 concentrations IOPT 15 IOPT 16 IOPT 17 IOPT 18 IOPT 19 0 IOPT 20 Oy ky Gr 2 IOPT 21 0 IOPT 22 0 IOPT 23 IOPT 24 0 6F ak IOPT 25 AQIAGDLS WP5 JUNE 1996 Rev 2 Delete met data on hourly contributions Delete case study printout of plume transport and dispersion on hourly contributions Delete hourly summary of receptor 1 Delete met data on hourly summary Delete case study printout of plume transport and dispersion on hourly summary Delete avg period contributions Delete averaging period summary Delete avg concentrations and hi 5 table OTHER CONTROL AND OU
60. s averaging periods are to be obtained directly from the modeling results of each construction activity The annual average is then obtained by summing the scaled annual average impact from each separate construction activity The annual average impact is not necessarily a calendar year but is the running year during which the maximum construction impacts would occur 2 Onshore Construction Fugitive Emissions Fugitive dust emissions occurring as a result of construction activities are to be modeled consistent with the protocol for construction combustive emissions except that the fugitive emissions are to be modeled for all 24 hours of the day This is consistent with the district protocol of calculating average fugitive dust emissions based on a 24 hour day which includes periods of active construction as well as periods of inactivity The keyword EMISFACT under the Source pathway is not used in this case a Onshore Operational Fugitive Emissions ROC Operational fugitive ROC emissions are assumed to be constant and not a function of time of day The keyword EMISFACT under the Source pathway is not used in this case Air quality impacts for all averaging periods are to be modeled using th ntire year of preconstruction monitoring PCM meteorological data b Onshore Operational Fugitive
61. s 919 541 5742 When obtaining an air quality model from somewhere other than the District it is imperative that the model be the most up to date version available Please consult with District staff to assure that the correct version is being used AQIAGDLS WP5 JUNE 1996 Rev 2 TABLE 1 Generic Project Scenarios and Required Modeling Analyses rr ee Preliminary Screening Analysis Screening Anal Refined Onshore Analysis Point Sources in Simple Terrain Building Downwash Analysis Area Volume Line Sources construction and fugitives Point Sources in Complex Terrain Refined Offshore Analysis All Sources Alternative model xx Complex projects with both onshore and offshore components may have to perform multiple modeling analysis AQIAGDLS WP5 JUNE 1996 Rev 2 E Submittals to the District Upon completion of the model runs the applicant must provide the District on hard copy and magnetic media IBM compatible 3 5 high density diskettes all material leading to and including the final output s This would include but not be limited to all input files control files output files pre and post processor programs and their input output and control files and all models used In short supply all the information needed to duplicate the work submitted by the applicant II Screening Analysis A General Information A screen
62. simulate lutants ar pho leria ling from t entitled CARB ul to so cludin tion in y standards existing tional standards are the established criteria consider the background air q uality levels in consumption ich to limit the area All increment two types of pollutants e commonly modeled using tochemical pollutants n schemes This document Guidance on reactive the California Air Technical Guidance 1990 me general aspects of the g discussions on the lowed while performing an AQIA what models where to an the pr the ozone limiting me obtain the models and d OCD Section VII oper use of background thod Sections VIX and X discuss the proper placement of receptors and the use of offs Sect ets in the AQIA ion XI respec tively Ref rences are provided in AQIAGDLS WP5 JUNE 1996 Rev 2 Ts Introduction A General Procedures An inert pollutant modeling assessment will normally involve a two phased approach The first phase of the assessment is to apply a simple screening procedure to determine if either The source clearly poses no air quality problem or The potential for an air quality problem exists If the screening procedures indicate that there may be a potential air quality problem a refined analysis must be undertaken Both screening and refined analyses are d
63. t are not collocated can be run separately with the same receptor grid and the resulting concentrations can then be added together using the postprocessor ANALYSIS program Bau Model Inputs Ly Source Inputs For each pollutant source modeled the following inputs are required Source UTM coordinates Km and elevation ft Stack height m Stack diameter m Stack exit gas temperature K Stack exit gas velocity m s emission rate g s 28 Terrain Profile Input RTDM must be informed of the terrain surrounding a source in terms of a terrain profile This terrain profile contains terrain heights up to 19 along each of the 36 wind directions at 10 degree intervals These terrain heights are to be obtained from 7 5 minute USGS topographical maps Terrain profiles are to be constructed following the procedures outlined in the RTDM manual in Section 2 14 and Section 5 1 4 It is important to note that for each direction an appropriate elevation contour increment should be selected based on the lowest and highest elevations downwind Terrain profiles are entered through the TERRAIN section in RTDM 54 Meteorological Inputs There are two different meteorological data sets that are to be used in RTDM runs The first meteorological data set represents worst case meteorological conditions and consists of 36 hours corresponding to 36 wind di
64. tack Emissions Data Do not use this option PRO25 Verbose Output Set this to 1 to produce verbose output for the preliminary run and set to 0 for the refined run 2 STACK Keyword 17 AQIAGDLS WP5 JUNE 1996 Rev 2 This section is used to describe the source characteristics in terms of its location emission rate pollutant and stack parameters A maximum of 35 sources can be input to RTDM An applicant must follow the format listed in Section 5 1 2 in the RTDM user s guide Si POINTS Keyword POINTS section is used to identify receptors by their coordinates elevation and names Please follow the format specified in Section 5 1 3 in the user s guide 4 TERRAIN Keyword This section defines terrain around a source An applicant must input terrain values in each of 36 wind directions in 10 degree intervals Please follow the procedure for constructing the terrain profiles outlined in Section 5 1 4 in user s guide Dig EXECUTE Keyword This is the last keyword used in RTDM input run stream This keyword terminates the reading of the input run stream and initiates program execution Please follow the input format described in Section 5 1 5 in the user s guide D Running RTDM 1 Discussion Two model runs are required for each source a preliminary run and a refined run The preliminary run is needed to obtain an indication of where the highest impacts are likely to occu
65. the maximum ambient concentration for screening purposes In general the full meteorology option should be run However if a source operates only certain hours during a day it may be more appropriate to set specific stability and wind conditions For receptors the automated distance array option should generally be selected The shortest distance from the source to its property boundary should be input as the minimum receptor distance but in no case should the minimum distance be less than 100 m The maximum distance should be selected such that the maximum impact has been covered for the source of interest The model will calculate the distance to maximum impact within the distance range input Cr Averaging Time Conversions The screening procedure outlined in this section will estimate both 1 hour and 24 hour concentrations are 3 hour 8 hour and annual average standards AQIAGDLS WP5 JUNE 1996 Rev 2 For some pollutants there The applicable conversion factors to be used are summarized below a Simple Terrain Modeling Result Desired Averaging Time Conversion Factor Hour 3 Hour 0 90 Hour 8 Hour 0 70 Hour 24 hour 0 40 Hour Annual Avg 0 10 b Complex Terrain Modeling Result Desired Averaging Time Conversion Factor 24 Hour 24 Hour LL A 1 Hour 4 0 Annual Avg 0 4 Modeling Point Sources with ISCST
66. tion to the annual average ambient NO2 value obtained from the period of air quality data IX Receptor Grid Spacing A General Requirements Each of the models discussed in these guidelines requires th input of receptor data The complexity of the receptor data will vary according to the model being used and the project being analyzed Some general requirements for receptor data are listed below Receptors should be placed at 250 meter intervals on a cartesian grid Receptors should be placed at specific discrete points to ensure that maximum potential impact is modeled for example on facility boundary line or on sub grid size terrain features Receptors should not be placed inside the applicant s facility boundaries Receptors should be placed starting at discrete points along the facility boundary line 100 meter intervals or along an arc 100 meters away from the nearest source s depending on which distance is greater from the source in question All receptor data location elevation are to be obtained from 7 5 minute USGS or more detailed topographic maps The receptor grid should be large enough in extent to cover region s of significant impact s The following sub sections discuss some model specific requirements for receptor placement B Model Specific Requirements ile SCREEN SCREEN provides the user an option to use an automated d
67. titude of the source region The actual height at which the wind data used in modeling were taken should be specified as the anemometer height HANE Surface roughness lengths ZOL for various types of terrain are listed in Table 4 A weighted average roughness length for the source receptor area should be used based on the distribution of terrain and vegetation types The minimum height of the plume above terrain ZMIN should be set to 10 0 meters Ez Point Source Description Information The following inputs are required for each source of emissions modeled source location Universal Transverse Mercator UTM coordinates pollutant emission rate width and height of 30 AQIAGDLS WP5 JUNE 1996 Rev 2 tallest building at or near stack location height of stack top above reference level stack gas temperature stack inside diameter stack gas exit velocity deviation of stack angle from the vertical and the source ground level elevation All of these parameters must be reviewed by the District engineering staff prior to submission of modeling results Maximum hourly emission rates are to be used in modeling all averaging periods less than or equal to 24 hours Annual average emission rates are to be used in modeling all annual average concentrations Emission rates are described in Section I B of this manual TABLE 3 Main Model Options for OCD Simulation
68. uality data from the same site used above determine the five highest ozone days recorded for the period Eliminate extreme ozone days from the period of data as follows 1 year of data discard highest day from period 2 years of data discard 2 highest days from period 3 years of data discard 3 highest days from period Review the remaining period of air quality data to determine the maximum simultaneous hourly sum of ozone and NO2 Assume that ten percent of the NO emissions are in the form of NO2 at the stack 0 1 NOXMAX Compare the remaining NO 0 9 NOXMAX to the ozone concentration during the hour which contained the maximum sum of ozone plus NO2 If the ozone concentration is greater than 0 9 NOXMAX then total conversion to NO is assumed NOXMAX NO If not then the NO concentration is set equal to the ozone concentration and added to the stack NO portion The calculated NO concentration resulting from the source is then added to the NO concentration during the hour which contained the maximum sum of ozone plus NO2 45 AQIAGDLS WP5 JUNE 1996 Rev 2 Compare the value obtained in the above step to the one hour CAAQS for NO2 For annual NO concentrations use the same period of meteorological data as input to the model and determine th maximum annual NO concentration Assume 100 percent conversion of NO to NO2 and add the resultant NO concentra
69. ures must be clearly described so that District staff can approve the methodology being proposed This protocol process saves both time and money if used correctly B Source Parameters For each source of pollutants modeled required Emission rates used as input must be the appl Source occurred or will are colleci other permiti source coordinates UTM pollutant emission rate g s stack height m stack gas exit temperature K stack gas exit velocity m s source elevation m All emission capacity a included in Maximum ho calculations All of District engineering st Cx Models For iner u implemented ar SCREEN ISCST less ISCST occur after ted must be included ted sources which were not the time of preconstruction monitoring must be the modeling t pollutant modeling as follows rly emission rates are averaging periods less than or equal to 24 hours emission rates are to be used for these parameters taff prior to exec For modeling inert point sources which impac than the height of must also be used increases from to be annual AQIAGDLS WP5 JUNE 1996 Rev 2 the following inputs are to the models for a proposed source icable emission increases from the stationary the source which have the preconstruction monitoring data Additionally
70. us United States U S Environmental Protection Agency Report No AP 101 Paine Robert J and Bruce A Egan 1987 User s Guide to the Rough Terrain Diffusion Model RTDM Rev 3 2 Doc No P D535 585 Pierce T and D Bruce Turner 1980 User s Guide for MPTER Santa Barbara County Air Pollution Control District Air Quality Monitoring Protocol for Preconstruction and Postconstruction Monitoring in Santa Barbara County California 8 November 1985 TRC Environmental Consultants Inc 1986 Industrial Source Complex ISC Dispersion Model User s Guide Second Edition Volume 1 Prepared for The Environmental Protection Agency Research triangle Park NC PB86 234259 U S Environmental Protection Agency Guideline on Air Quality Models Revised July 1986 49 AQIAGDLS WP5 JUNE 1996 Rev 2 U S Environmental Protection Agency 1986 User s Network for Applied Modeling of Air Pollution UNAMAP Computer Programs on Tape National Technical Information Service Springfield VA U S Environmental Protection Agency 1977 Guidelines for Air Quality Maintenance Planning and Analysis Volume 10 revised EPA 450 4 77 001 U S Environmental Protection Agency 1977 User s Manual for Single Source CRSTER Model EPA 450 2 77 013 Wagner Kit K 1984 User s Guide to the California Air Resources Board Air Quality Modeling Section Fumigation Models Technical Support Divisi

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