**9 th** **Conference on Air Quality Modeling – A&WMA AB3** **Comments on CALPUFF Presented by** **Gale F. Hoffnagle, CCM,QEP TRC Environmental Corporation** **21 Griffin Road North Windsor, CT 06095** **ghoffnagle@trcsolutions.com Comment Areas** **• CALPUFF fulfills an important modeling need • EPA Concerns about CALPUFF** **• EPA control of model development and coding • Use at less than 50 kilometers** **• Use at greater than 200/300 kilometers CALPUFF Fulfills an Important** **Modeling Need • Many applications require air quality impacts** **from individual stacks for long distances • Need a 3-D Lagrangian model – Eulerian model** **will not work well for individual sources. Current subgrid scale modules in Eulerian models are** **too simplistic. • CALPUFF is a model with substantial user** **community experience • Better handling of low wind speed cases,** **stagnation, coastal, complex terrain and flow reversals.** **• Better handling of deposition EPA Concerns about CALPUFF** **• EPA concerned that near field evaluations of CALPUFF has been somewhat limited, especially** **in near field (8 new studies) • Some aspects of the approved model are now** **about 25 years old – Substantial EPA resources may be needed to** **evaluate and approve upgrades as opposed to EPA working on consideration of newer** **alternative models – Chemistry fine for NOx,SO2 and PM.** **EPA Doesn’t Have Direct Control of the CALPUFF Code – Advantages** **• EPA has control of the “regulatory” code • Developer has multiple funding sources and the** **resources to provide for advances in this model • Developer provides training courses for** **CALPUFF • Developer provides continuous support for** **model maintenance, expanded GUI’s, etc. which EPA would not be able to do.** **• AWMA supports an independent Workgroup EPA Doesn’** **t Have Direct Control of the CALPUFF Code – Disadvantages** **• EPA has not been able to supply any funding to provide modeling updates that EPA** **wants • As a result, EPA says...** **– CALPUFF user guide lags far behind updated code releases - last user guide (v.5.8) released in 2006** **– Some of the latest guidance is only available if y ou** **attend a course given by TRC (v 6 users guide awaiting EPA approval of code)** **– Code changes made without EPA oversight and funding require extensive EPA review.** **– Coordination between EPA and TRC needs to be improved** **CALPUFF at Less Than 50 Kilometers** **• Why 50 kilometers? Should be based on transport time.** **• Requiring “equivalency” is too restrictive • Better method is to define more precisely** **when “complex winds” require puff modeling as suggested previously** **• Adding bells and whistles to AERMOD will not make it Lagrangian** **CALPUFF at greater than 200/300 Kilometers** **• CALPUFF comparisons to long range transport studies have shown relative** **accuracy to 200 kilometers • FLAG says to use out to 300 kilometers** **• Many States, RPOs and Regions are using out to 600 kilometers and more** **• Either there should be a defined outer limit or more LRT field studies should be** **conducted AWMA Specialty Conference** **• “Guideline on Air Quality Models: Next Generation Models”** **• RTP October 26-30, 2009 • Call for Papers out soon. Look for it at** **www.AWMA.org**