On Tuesday, October 28, CPP Vice President Dr. Ron Petersen will be presenting at the 54^th Annual Conference of the Pacific Northwest International Section (PNWIS) of the Air & Waste Management Association (A&WMA). His talk is titled, “Implications of Accurate Source Characterization On Permitting for the 1-hour NAAQS.”

The 2013 EPA Draft SO₂ NAAQS Designations Modeling Technical Assistance Document states that it is critical to characterize the modeled facility accurately. According to the document, inaccurate building information will produce inaccurate downwash information when using AERMOD. Dr. Petersen’s presentation will discuss two generic facilities, modeled with AERMOD:

• The first has a 31m-high long, narrow, solid building and a single stack that is 1.5 times the building height,
• The second has two 50m-high porous structures located near a single stack of the same height.

Accurate building information was assembled for these two facilities and input into BPIP.  The BPIP AERMOD input file was analyzed and the following problems were found: 1) building widths and/or lengths outside the range of AERMOD theory; and 2) the porous structures were assumed to be solid. Although the site information was accurate, BPIP generated building dimensions for AERMOD input did not result in accurate predictions.  For comparison, an EPA “Source Characterization” study was conducted where Equivalent Building Dimensions (EBD) were defined that more accurately modeled the dispersion for these two sites.  AERMOD was then run using the original BPIP determined inputs and the refined inputs based on a more accurate “Source Characterization.”

By refining BPIP inputs, the maximum 1-hr concentrations decreased by factors of 2 to 3.5  Due to the stringent nature of the 1-hr NAAQS, a more accurate source characterization study should be high on the list of refined modeling options.

About the speaker

Dr. Ron Petersen is Vice President of Environmental Services at CPP and a pioneer in the physical modeling of exhaust behavior. He is a Certified Consulting Meteorologist and internationally recognized as a leader in his field. He has more than 30 years of experience performing physical modeling, mathematical modeling, and analyses to accurately assess industrial emissions.

Dr. Petersen can be reached at ron.petesen@cppwind.com or 970 221 3371.