Environmental Justice Enhancement I-4: Localized Significance Thresholds – Staff Proposal

1. Environmental Justice Enhancement I-4: Localized Significance Thresholds – Staff Proposal June 19, 2003

2. Localized Significance Thresholds - Background • EJ Initiative #4 – Establish Stakeholder Working Group to revise Handbook • Stakeholder Working Group identified localized significance thresholds (LSTs) as a topic to include in the Handbook • Developed concept of LST Lookup Tables • February 1, 2002 – Governing Board directed staff to continue developing LST • September 13, 2002 – Governing Board adopted EJ Enhancements: Enhancement I-4 directs staff to continue developing LSTs

3. Significance Threshold - Approaches

4. Localized Significance Thresholds - Methodology • AAQS Exceedance Approach for Attainment Pollutants - NO2 & CO • Emissions contribution from the project added to ambient concentrations • Localized thresholds in mass daily emissions developed by SRA, size of emissions source (< 5 acres) & receptor distance

5. Localized Significance Thresholds - Methodology (Cont.) • CO Basis • Highest 1-hr & 8-hr CO background conc. over 3-year rolling average (1999-2001) • Single table developed from the lower emissions allowed by either the 1- or 8-hr conc. • NO2 Basis • Highest 1-hr NO2 background conc. over a 3- year rolling average (1999-2001) • Gradual NO to NO2 conversion

6. Localized Significance Thresholds - Methodology (Cont.) • PM10 - Construction • Applicable primarily to fugitive dust activities • Would encompass PM10 from all emission sources – dust and combustion • Significance threshold consistent with Rule 403 • Back calculates mass emission that cause an exceedance of Rule 403-equivalent threshold of 10.4 µg/m3 (24-hour average)

7. Localized Significance Thresholds - Methodology (Cont.) • PM10 - Operation • Significance threshold consistent with Rule 1303 modeling requirement of 2.5 µg/m3 • Back calculates mass emissions that cause an exceedance of 2.5 µg/m3 • Applies to all emission sources

8. Intent of Localized Significance Thresholds Tables • Similar to Rule 1401/212 guidance, users have the option of using screening (look-up) tables for projects < to 5 acres or performing project-specific modeling (Tiers III or IV) • Consistent with modeling for Reg. XIII • Users of criteria pollutant screening tables would need less resources

9. Localized Significance Thresholds - Conclusion • Staff proposal for LSTs would implement EJ enhancement I-4 • Provides another indicator of A.Q. significance for CEQA analysis • Would be incorporated into revised Handbook • LSTs are guidance, not mandatory • Tiered approach to assess localized impacts • Lead agencies can use LST look-up tables (< 5 acres) • Or perform site-specific modeling

10. Localized Significance Thresholds – Conclusion (Cont.) • Using LST look-up tables • Requires less resources • No additional emission calculations necessary to use LST Look-up tables • More conservative (based on conservative assumptions) • Site specific modeling • Requires more resources • More flexibility • More precise results • Staff to continue identifying mitigation measures as part of revised Handbook & on a project-specific basis

11. Localized Significance Thresholds - Schedule • Public Consultation Meeting 6/19/03 • Accepting comments until 6/26/03 • Scheduled for Public Hearing and consideration by Governing Board 7/11/03