DSHW-2012-005802 - 0901a068802f23ee

25 July 2012
8200-FY13-019
Mr. Scott T. Anderson, Executive Secretary
State of Utah Department of Environmental Quality
Division of Solid and Hazardous Waste
195 N.1950 W.
P.O. Box 144880
Salt Lake City, Utah 84114-4880
Re: ATK Launch Systems-Promontory EPA ID number UTD009081357
Revised Air Dispersion Modeling Assessment Report for Open Burn and Open
Detonation Treatment Units
Dear Mr. Anderson:
Enclosed is the Revised Air Dispersion Modeling Assessment Report for the Open Burn
and Open Detonation treatment units located at ATK's Promontory facility. As discussed
with your Division, this modeling assessment is a tiered approach. This modeling review
has been conducted using the Open Burn/Open Detonation Model (OBODM) and
represents an initial screening level assessment using a very conservative modeling
approach with an older model with limited source dispersion and deposition capability.
ATK requests that the next step in this tiered modeling assessment be conducted using a
"hybrid" modeling approach. This hybrid incorporates the source algorithms from
OBODM as an input parameter into the dispersion model AERMOD. AERMOD is then
used to evaluate the dispersion and deposition parameters need to conduct the OB/OD
human health risk assessment. AERMOD is a recommended/preferred dispersion model
by the US EPA and allows a more refined modeling analysis for the National Ambient
Air Quality Standards (NAAQS), Utah Toxic Screening Levels (TSLs), and a better
assessment in complex terrain. ATK requests written concurrence from the Division to
proceed with the "hybrid modeling analysis." After receiving the Divisions concurrence
ATK will submit an addendum to the Dispersion Modeling Protocol for the "hybrid
modeling analysis."
Please contact me if you have any questions concerning this report. My telephone
number is [phone] or you can contact Blair Palmer at [phone].
Sincerely
Robert Ingersoll, Director
Environmental Services
cc: JeffVandel
Division of
Solid and Hazardous Waste
JUL 2 5 2012
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