Air Dispersion Modeling of HAP Emissions from SSFL

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Air Dispersion Modeling of HAP Emissions
from SSFL
Prepared by Lyle Chinkin Patrick A. Ryan,
Ph.D. Neil J. M. Wheeler, CCM Sonoma Technology,
Inc. Petaluma, CA
Presented at UCLA SSFL Public Health Initiative
Information Meeting Grand Vista Hotel Simi
Valley, CA August 19, 2003
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Purpose

• Simulate how emissions from the SSFL may have
  been transported and dispersed in the atmosphere
• Provide spatial patterns of potential atmospheric
  exposure to emissions from the SSFL for further
  analysis by UCLA

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Dispersion Models

• Represent mathematically the transport (movement)
  and dispersion (spreading and dilution) of gases
  or particles emitted into the atmosphere

Emissions
Model
Air Quality
Meteorology
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Area

• The modeling domain is centered on the SSFL and
  extends more than 50 kilometers in all directions

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Emission Sources Modeled

• Rocket engine exhaust
• Cleaning and degreasing agents at test stands
• Open burning
• Stripping towers
• Applicable to radioactive sources

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How Emission Sources Were Modeled

• 24-hours per day
• daylight hours only
• increasing activity throughout daylight hours

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Meteorology

• Four years (1994 to 1997) of on-site meteorology
  from Area IV
• Evaluated Representativeness by
• Comparing to Area I winds (partial year)
• Comparing to Canoga Parks winds
• Reviewing 1949 to 2002 rainfall
• Visually inspecting facility wind patterns

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Wind Roses
Daytime winds mostly out of the Northwest
North
700 AM to 8 00 PM
20
16
12
8
East
West
Wind Speed (mph)
gt24
15-24
13-15
6-13
3-6
1-3
South
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Wind Roses
Winds equally out of the Northwest and Southeast
North
SSFL Area IV 1994 - 1997 All hours
15
12
9
6
East
West
Wind Speed (mph)
gt24
15-24
13-15
6-13
3-6
1-3
South
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Dispersion Modeling

• EPA approved puff dispersion model
• Unit emission rate to represent the source types
• Four (4) year simulations
• Annual averages calculated from hourly values

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Results

• Annual air quality patterns align with wind
  patterns
• Maximum ambient
  concentrations are
  located toward the SE
  lesser toward NW

Simi Valley
SSFL
LA Metro Area
Agoura Hills