Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 1 Barbara Roach Non-Title V Permit Engineer Maricopa Quality Air Quality Department (602)

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 2 Collocated Rock Products Plants Interim modeling procedure for two or more “collocated sources” Procedure does not include “clustered sources” “Clustered sources” operate independently but are located in close proximity to each other

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 3 Definition of Source “Any building, structure, facility, or installation that may cause or contribute to air pollution.” [Rule 100 § 200] All pollution-emitting equipment that belong to same industrial grouping, located on contiguous or adjacent property, and under common control are considered one source.

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 4 Definition of Collocation Collocated sources will meet the following criteria: Operate under common control –site management with decision making authority over operations – contract for service – a support/dependency relationship (over 50% of production) – same owner

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 5 Definition of Collocation Are located on contiguous or adjacent property Have the same major Industrial Grouping (SIC code) –Support activities are part of the same industrial grouping even if they have two different SIC codes (e.g. sand & gravel mining, SIC code 14 and asphalt production, SIC code 29)

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 6 Todd Martin Non-Title V Permit Engineer Maricopa Quality Air Quality Department (602)

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 7 Dispersion Modeling Permittee shall conduct a dispersion model analysis for PM-10 Purpose: Determine whether source will contribute to a violation of any National Ambient Air Quality Standard (NAAQS): –Annual PM-10 standard = 50 µg/m 3 –24 hour PM-10 standard = 150 µg/m 3 Modeling: –Is performed on the air emissions from the entire facility –Covers releases occurring during normal business operation; it does not cover catastrophic or accidental releases –Takes background concentrations into consideration, to understand possible cumulative effects

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 8 Modeling Process A screen model may be run to determine the maximum off site concentration Incorporate background concentrations from nearest Maricopa County monitoring station –Background = Annual average –Available on MCAQD web site (Air Monitoring) If the modeled concentrations are greater than the NAAQS, then more refined modeling may be performed (AERMOD)

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 9 Modeling Guidelines EPA Guideline on Air Quality Models (40 CFR Part 51 Appendix W, November 2005) ADEQ Air Dispersion Modeling Guidelines for Arizona Air Quality Permits (December 2004)

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 10 AERMOD Modeling Process Submit a modeling protocol to the Department –Project background –Regional characteristics (model parameters) Geology Metrology Facility layout Emission profiles for each source of PM-10 Stack parameters Other modeling assumptions used MCAQD Approval of Protocol

Maricopa County Air Quality Department 1001 North Central Ave. Phoenix, Arizona Maricopa County Air Quality Department Protecting and improving our most basic resource 11 Dispersion Model Analysis Ambient PM-10 impact is based on: 1.Annual: The highest estimated annual average concentration determined from annual averages of individual years; 2.24-Hour: The highest, second-highest estimated concentration; 3.Add: The annual average PM-10 concentration from nearest monitoring station 4.Compare result with NAAQGS If model indicates an exceedance of NAAQGs, MCAQD reserves the right to deny the Permit Application