This page lists some known alternative models to the perferred/recommended models listed in the that can be used in regulatory applications with case-by-case justification to the Reviewing Authority (Section 3.2 of Appendix W). However, inclusion here does not confer any unique status relative to other alternative models that are being or will be developed in the future. The models in this section include,.

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Alternative Models and DocumentationADAMAir Force Dispersion Assessment Model (ADAM) is a modified box and Gaussian dispersion model which incorporates thermodynamics, chemistry, heat transfer, aerosol loading, and dense gas effects. Release scenarios include continuous and instantaneous, area and point, pressurized and unpressurized, and liquid/vapor/two-phased options.Model Code(271 K)Model Documentation(1 K)ADMS-3Atmospheric Dispersion Modeling System (ADMS-3) is an advanced dispersion model for calculating concentrations of pollutants emitted both continuously from point, line, volume and area sources, or discretely from point sources.

Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere.It is performed with computer programs that include algorithms to solve the mathematical equations that govern the pollutant dispersion.

The model includes algorithms which take account of the following: effects of main site buiding; complex terrrain; wet deposition, gravitational settling and dry deposition; short term fluctuations in concentration; chemical reactions; radioactive decay and gamma-dose; plume rise as a function of distance; jets and directional releases; averaging time ranging from very short to annual; condensed plume visibility; meteorological preprocessor.The modeling system is available at no cost in selected circumstances. Potential users should contact Dr.

David Carruthers at 'David.Carruthers@cerc.co.uk' for information on acquiring the ADMS-3 modeling system. For additional information on the ADMS-3 Modeling System please link to the.AFTOXAFTOX is a Gaussian dispersion model that will handle continuous or instantaneous liquid or gas elevated or surface releases from point or area sources. Output consists of concentration contour plots, concentration at a specified location, and maximum concentration at a given elevation and time.Model Code and Documentation(173 K)(26 K)ASPENThe Assessment System for Population Exposure Nationwide (ASPEN) consists of a dispersion and a mapping module. The dispersion module is a Gaussian formulation based on ISCST3 for estimating ambient annual average concentrations at a set of fixed receptors within the vicinity of the emission source. The mapping module produces a concentration at each census tract. Input data needed are emissions data, meteorological data and census tract data.

The Emissions Modeling System for Hazardous Pollutants is needed to process the emission inputs into the ASPEN model or the model. The ASPEN model was used in estimating annual ambient concentrations for air toxics pollutant in the.Model Code(3.7 M)Model Documentation(1 pg, 30 K)(110 pp, 1.5 M, 2000). The ASPEN model and the EMS-HAP Version 3.0 emission modeling system were used to estimate the ambient concentrations for the National-Scale Air Toxics Assessment for 1999. The 2005 results are available on the. (16 pp, 145 K, 2008)DEGADISDEGADIS simulates the atmospheric dispersion at ground-level of area source dense gas (or aerosol) clouds released with zero momentum into the atmospheric boundary layer over flat, level terrain.

The model describes the dispersion processes which accompany the ensuing gravity-driven flow and entrainment of the gas into the boundary layer.Model Code(3.2 M)(266 K)(334 K)Model Documentation(12 pp, 60 K)(419 pp, 9.6 M, 1989)(114 pp, 3.5 M, 1990)Latest (1 K, 2012)HGSYSTEMHGSYSTEM is a collection of computer programs designed to predict the source-term and subsequent dispersion of accidental chemical releases with an emphasis on denser-than-air (dense gas) behavior. Available from, Order Number PB96-501960.HOTMAC/RAPTADHOTMAC is a 3-dimensional Eulerian model for weather forecasting; RAPTAD is a 3-dimensional Lagrangian random puff model for pollutant transport and diffusion. These models are used for prediction of transport and diffusion processes for complex terrain, coastal regions, urban areas, and around buildings where conventional models fail. Available from.HYROADThe HYbrid ROADway Model (HYROAD) integrates three historically individual modules that simulate the effects of traffic, emissions and dispersion. The traffic module is a microscale transportation model which simulates individual vehicle movement. The emission module uses speed distributions from the traffic module to determine composite emission factors; spatial and temporal distribution of emissions is based on the vehicle operation simulations.

The model tracks vehicle speed and acceleration distributions by signal phase per 10-meter roadway segment for use in both emissions distribution and for induced flows and turbulence. The dispersion module uses a Lagrangian puff formulation, along with a gridded non-uniform wind and stability field derived from traffic module outputs, to describe near-roadway dispersion characteristics. HYROAD is designed to determine hourly concentrations of carbon monoxide (CO) or other gas-phase pollutants, particulate matter (PM) and air toxics - in consultation with appropriate Reviewing Authority - from vehicle emissions at receptor locations that occur within 500 meters of the roadway intersections.Model Code and Documentation(13.5 M)(1.8 M)(1 M)ISC3ISC3 is a steady-state Gaussian plume model which can be used to assess pollutant concentrations from a wide variety of sources associated with an industrial complex. This model can account for the following: settling and dry deposition of particles; downwash; point, area, line, and volume sources; plume rise as a function of downwind distance; separation of point sources; and limited terrain adjustment. ISC3 operates in both long-term and short-term modes. The screening version of ISC3 is.

ISC3 also uses the Emissions Modeling System for Hazardous Pollutants to process an emission inventory for input into the model. The Building Profile Input Program and the Building Profile Input Program for PRIME can also be used with ISC3 to correctly calculate building heights (bh) and projected building widths (pbw) for simple, multi-tiered, and groups of structures. For the status of ISC3 as a preferred model, please see the below.Model Code(1.7 M)(390 K)Model Documentation(390 pp, 1.4 M, 1990)(128 pp, 570 K, 1995)Latest (29 K, 2002)Latest (45 K, 1996). The promulgation package which establishes as the preferred air dispersion model in the Agency's 'Guideline on Air Quality Models' in place of the ISC3 air dispersion model was signed by the Administrator of the US EPA on October 21. The package was then submitted to the Federal Register office and was published November 9, 2005.This rule becomes effective December 9, 2005. Beginning one year after this date, the new model -should be used for appropriate application as replacement for ISC3. During this one-year period, protocols for modeling analyses based on ISC3 which are submitted in a timely manner may be approved at the discretion of the appropriate Reviewing Authority.

Applicants are therefore encouraged to consult with the Reviewing Authority as soon as possible to assure acceptance during this period.ISC-PRIMEISC-PRIME (Plume RIse Model Enhancements) is a model with building downwash incorporated into the Industrial Source Complex Short Term Model.Model Code(217 K)(639 K)Model Documentation(8 K, 2004)(13 pp, 229 K, 1997)(162 pp, 262 K, 1997) - Graphics are not included in document. Complete copy is available from NTIS.

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(See README for ordering information.)Consequence Analysis - Available from NTIS (See README for ordering information.)(7 pp, 22 K, 1998) and (3 pp, 24 K, 1998)(47 pp, 903 K, 1998)Technical Papers(5 pp, 19 K)(4 pp, 32 K)(34 pp, 588 K)OBODMIntended for use in evaluating the potential air quality impacts of the open burning and detonation (OB/OD) of obsolete munitions and solid propellants. OBODM uses cloud/plume rise dispersion, and deposition algorithms taken from existing models for instantaneous and quasi-continuous sources to predict the downwind transport and dispersion of pollutants released by OB/OD operations.Model Code(524 K, February 9.

Dispersion modeling is generally associated with the construction permit application process and is used to predict the air quality impact of new or modified emission sources. Other uses of dispersion modeling include: analysis of monitored violations of the National Ambient Air Quality Standards (NAAQS), assistance in planning and the development of rules. The following information is provided as general guidance to help you through the air quality modeling process. Although the intent is for the information to be as complete as possible, modeling methodologies and analyses can vary on a project-by-project basis.

Please work in close consultation with the Virginia DEQ modeling staff and the appropriate as you develop your modeling protocol and air quality compliance demonstration. Air Quality ModelsThese refined dispersion models that are used for regulatory applications are listed in the and are used for State Implementation Plan (SIP) revisions for existing sources and for the New Source Review (NSR) and Prevention of Significant Deterioration (PSD) programs. EPA maintains the list of preferred/recommended models on the website.- EPA's list of preferred/recommended dispersion models for regulatory applications.- A steady-state plume model that incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concepts, including treatment of both surface and elevated sources, and both simple and complex terrain.- A non-steady-state puff dispersion model that simulates the effects of time- and space-varying meteorological conditions on pollution transport, transformation, and removal. CALPUFF can be applied for long-range transport and for complex terrain on a case-by-case basis.- Other dispersion models including BLP, CALINE3, CAL3QHC/CAL3QHCR, CTDMPLUS, and OCD. Modeling GuidanceVirginia DEQ GuidanceA copy of Virginia's primary permit modeling guidance, Virginia Modeling for Air Quality Permits, can be obtained by contacting.

Environmental Protection Agency (EPA) Guidance- This website is maintained by EPA's Air Quality Modeling Group (AQMG). The AQMG conducts modeling analyses to support policy and regulatory decisions in the Office of Air and Radiation (OAR) and provides leadership and direction on the full range of air quality models and other mathematical simulation techniques used in assessing control strategies and source impacts. Documentation and guidance for these air quality models can be found on this website, including downloadable computer code, input data, and model processors.(Adobe pdf) - EPA’s Guideline on Air Quality Models (‘‘Guideline’’) addresses the regulatory application of air quality models for assessing criteria pollutants under the Clean Air Act.(Adobe pdf) - This document provides information on the recommended use of AERMOD to address specific issues and concerns related to the implementation of AERMOD for regulatory applications. The following recommendations augment the use of experience and judgment in the proper application of dispersion models. Advanced coordination with DEQ, including the development of modeling protocols, is recommended for regulatory applications of AERMOD.(Adobe pdf) - This document was developed for use in conjunction with New Source Review (NSR) workshops and training, and to guide permitting officials in the implementation of the NSR program.

It is not intended to be an official statement of policy and standards and does not establish binding regulatory requirements; such requirements are contained in the regulations and approved state implementation plans.- The mission of OAQPS is to preserve and improve the quality of our nation's air. One facet of accomplishing this goal requires that new and existing air pollution sources be modeled for compliance with the National Ambient Air Quality Standards (NAAQS).Federal Land Managers' (FLM) Guidance(Adobe pdf) - Guidance developed by a group consisting of the National Park Service (NPS), the U.S. Fish and Wildlife Service (FWS), and the U.S. Forest Service (USFS). FLAG was formed to evaluate air pollution effects on air quality related values (AQRVs) primarily in Federal Class I air quality areas, but in some instances, in Class II areas; and to provide State permitting authorities and potential permit applicants consistency on how to assess the impacts of new and existing sources on AQRVs. Based on knowledge gained and regulatory developments since the original FLAG report was completed in December 2000, the federal land managers have revised FLAG resulting in the FLAG 2010 report. Additional information is also located on the.

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Meteorological Data and Monitoring GuidanceThis section provides information about meteorological data for regulatory air quality modeling. The OAQA has data from current and historic meteorological towers in Virginia that are suitable for use in regulatory models. Contact for available data. Approval must be obtained on a case-by-case basis before meteorological datasets are used for regulatory (e.g., air permit) modeling.(Adobe pdf) - This document provides guidance for the collection and processing of meteorological data for general use in air quality modeling applications. Such applications include those required in support of air quality regulations as specified in the Guideline on Air Quality Models.(Adobe pdf) - The purpose of this guideline is to address those items or activities which are considered essential in designing PSD air quality and meteorological monitoring networks.

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