A Land Use Tool for AERMOD Urban/Rural Classification John Glass South Carolina – BAQ

1. A Land Use Toolfor AERMOD Urban/Rural ClassificationJohn GlassSouth Carolina – BAQ

2. EPA 40 CFR Part 51, Appendix WRural-Urban Classification • Section 7.2.3: • c. Land Use Procedure: • (1) Classify the land use within the total area, Ao, circumscribed by a 3km radius circle about the source using the meteorological land use typing scheme proposed by Auer 73; • (2) if land use types I1, I2, C1, R2, and R3 account for 50 percent or more of Ao, use urban dispersion coefficients; otherwise, use appropriate rural dispersion coefficients. • d. Population Density Procedure: • (1) Compute the average population density, p per square kilometer with Ao as defined above; • (2) If p is greater than 750 people/km2, use urban dispersion coefficients; otherwise use appropriate rural dispersion coefficients. • e. Of the two methods, the land use procedure is considered more definitive.

3. SC-BAQ before 2008 • AQ modeling guidelines (2001): ”With few exceptions, all of SC is considered to be rural. Typically, the areas in the large metropolitan areas of the state (Greenville/Spartanburg, Columbia, and Charleston) will meet one of the … definitions of urban.” ►Limited population-based checking by SC-BAQ for facilities claiming “Urban” near metro “cores”

4. SC-BAQ starting in 2008 • Objective “Urban-Rural” Tool • Based on preferred LAND USE method • Uses GIS/ArcView • “Bridge” from Auer’s scheme to NLCD 2001

5. Auer vs. NLCD 2001

6. User’s Basic Steps 1. Open “Land Use” tool in ArcView 2. Enter Lat/Lon of facility 3. Create buffer (circle) at r=3 km 4. Activate % land use algorithm 5. Sum % for NLCD categories 23 & 24 (≥50%=URBAN, <50%=RURAL)

7. Example: Downtown Columbia

8. Results - % Land Use Algorithm 50% "Urban"

9. Compare 2 downtown locn’s

10. COMMENTS ?? • QUESTIONS ?? John Glass, 803-898-4074, glassjp@dhec.sc.gov