CALPUFF Services

In April 2003, the U.S. Environmental ProtectionAgency (EPA) approved CALPUFF as the preferredmodel for air dispersion modeling analyses involvinglong-range pollutant transport or complex terrain.CALPUFF is a non-steady state Lagrangian puffmodel that allows for refined representation oflong-range phenomena such as visibility, regionalhaze, and acid deposition through the use ofadvanced meteorological data. CALPUFF generallyuses three-dimensional meteorological fieldsdeveloped by the CALMET model. Since approximately 1995, Federal Land Managers(FLMs) have requested an air modeling evaluationas part of any Prevention of Significant Deterioration(PSD) permit application for sources located within100 kilometers of a protected Class I area todemonstrate the proposed project’s impact onthose areas. Today, CALPUFF is used to modelimpacts of sources located hundreds of kilometersaway from Class I areas including regional studiesthat encompass hundreds of sources. Since the regulatory approval of CALPUFF, manyregulators are requiring applicants to utilize thismodel as the sole means of quantifying Class I areaair impacts. This requirement poses a challengefor industry, as the CALPUFF modeling systemrequires considerable expertise and computerresources to execute, and its complexity can oftendelay the permitting process. With more than 30years of experience performing air quality studiesfor industrial facilities’ regulatory and strategicplanning needs, Trinity Consultants has theknowledge, experience, and computer resourcesto properly address the intricacies associated withCALPUFF modeling. CALPUFF Modeling CapabilitiesTrinity has performed screening and refinedCALPUFF studies involving Class I and Preventionof Significant Deterioration (PSD) modeling issuesfor facilities in a variety of industries. OurCALPUFF modeling experience is distinguished byour proficiency in obtaining, processing, andquality-assuring extensive meteorological andgeophysical data inputs; our familiarity withPSD/Class I analysis guidelines established by theEPA and the Federal Land Managers (FLMs); andour ability to prepare thorough, yet focused,modeling protocols and evaluation reports. Withthis start-to-finish approach, Trinity providesturnkey CALPUFF solutions to our clients, savingthem both time and money.Documents published by the Federal LandManagers Air Quality Related Values Work Group(FLAG) and the EPA Interagency Workgroup on AirQuality Modeling (IWAQM) guide long-rangetransport modeling conducted with the CALPUFFmodeling system. Trinity has experience applyingboth the FLAG and IWAQM guidance documents toCALPUFF modeling projects. However, becausethe FLAG and IWAQM documents have noregulatory authority, local and state groups oftenchallenge them. Trinity has worked extensivelywith Federal Land Managers (FLMs) throughoutthe nation to develop protocols and negotiateterms for projects used to assess air quality impacts.SERVICES REGULATORY COMPLIANCECALPUFF MODELING FOR LONG RANGE ANALYSISTrinity’s modelers have the meteorological expertise to handle CALPUFF’s extensive meteorological data requirements.CONSULTINGMeteorological Data Processing CapabilitiesStringent FLM assessment thresholds often dictatethat facilities complete a full CALPUFF analysis todemonstrate compliance with Class I area ambientthresholds. A full CALPUFF analysis requiressignificant meteorological data analysis prior torunning the models,including the use of acomplex prognosticmeteorologicalmodel. For theseanalyses, MM4 orMM5 meteorologicaldata is typically used. Based on EPA’sAppendix W finalrule, CALPUFFrequires 3-years ofmeteorological datawith mesoscale data,or 5 years of NationalWeather Service(NWS) data withoutmesoscale data.Trinity has stream-lined meteorologicaldata acquisition andprocessing, includingmesoscale data sets.Trinity has acquiredand processed severalnationwide mesoscaledata sets including the 80km x 80km 1990 MM4,80km x 80km 1992 MM5, and 36km x 36km 1996MM5 data sets. Moreover, Trinity has developedmore recent and refined MM5 data sets for regionaland specific project domains. Because Trinity hasthe expertise and computer resources to processand store the vast amount of data associated withthe MM5 format, Trinity has completed MM5CALPUFF analyses with a quick turnaround despitethe complexity and processing requirements. CALPUFF’s more accurate characterization ofatmospheric dispersion, especially with MM5 data,can lead to less conservative modeling results thanother models provide. This increased accuracymay provide increased operational flexibility forfacilities as compared to traditional, lesssophisticated models such as AERMOD and ISC. Air Quality and Dispersion Modeling Expertise Trinity can be of particular value to clientsbecause of our expertise and focus on air qualityregulatory issues. Trinity is widely recognized forskills in conducting dispersion modeling studies tosupport permit applications, compliance demonstrations, emergency response planning,and impact and feasibility assessments. Asregulatory dispersion modeling undergoes asignificant transition with the implementation ofnew state-of-the-art dispersion models, Trinity hasinvested in the intellectual and computingresources to maintain unparalleled modelingexpertise. Trinity also provides CALPUFF trainingtaught by senior-level consultants with extensiveair quality modeling and CALPUFF experience.(800) 229-6655Offices nationwidetrinityconsultants.comISC Concentration Predictions CALPUFF Concentration PredictionsThis simulation compares the predicted concentrations from a 500 tpy emission source, asevaluated with ISC and CALPUFF. In ISC, every hour corresponds to a beam of color – thedarker the color, the greater the concentrations. ISC treats every hour as a separate meteorological event that continues indefinitely, generating unrealistic concentrations.CALPUFF also models hourly areas of concentration but accounts for the effect of the meteorological data on the next hour, which creates amorphous areas of impact. Consequently,CALPUFF may predict a lower maximum concentration than ISC, as is the case here. Copyright 2006. All rights reserved.