San Luis Obispo County APCD

The San Luis Obispo County Air Pollution Control District's CEQA thresholds are in its CEQA Air Quality Handbook, which the APCD Board adopted in April 2012 with its CEQA thresholds. The district has since layered administrative updates onto it: a November 14, 2017 Clarification Memorandum, 2021/22 updates, and the 2023 update now posted as the current Handbook, which mainly changes Section 3.5.6 on greenhouse gases. The criteria pollutant numbers below are the Board-adopted 2012 values; the 2023 GHG thresholds are recommended for adoption by local jurisdictions.

Construction thresholds

Table 2-1, Thresholds of Significance for Construction Operations:

The values rest on the California Health and Safety Code and CARB's Carl Moyer Guidelines, and a footnote warns that a grading area over 4.0 acres of worked area can put dust past the 2.5 ton quarterly level. Mitigation starts when a level is equaled or exceeded:

• ROG + NOx. 137 lb/day: Standard Mitigation Measures, however short the job (a policy since October 2016). 2.5 tons a quarter: those plus Best Available Control Technology (BACT) for construction equipment; off-site mitigation may be required if feasible measures are not implemented or none are feasible. When emissions still exceed 6.3 tons a quarter after standard measures and BACT, Section 2.3.3 requires a Construction Activity Management Plan (CAMP) and off-site mitigation.
• Diesel PM. For construction expected to finish in less than one quarter, exceeding 7 lb/day requires standard measures. For construction lasting more than one quarter, exceeding 0.13 tons a quarter requires standard measures and BACT; exceeding 0.32 tons a quarter adds a CAMP and off-site mitigation. Section 2.3.3 applies the CAMP and off-site requirements to emissions remaining above Tier 2 after standard measures and BACT.
• Dust. 2.5 tons a quarter: fugitive PM10 measures and possibly a CAMP.
• GHG. Total construction GHG is divided by project life, 30 years for residential and mixed use and 25 for commercial, and added to annual operating emissions.

Off-site mitigation is priced at "$30,000 per ton" of ROG + NOx above the threshold for the length of the exceedance, plus a 15 percent administration fee (the 2012 rate) when the district runs the projects; a footnote ties the rate to the Carl Moyer cost-effectiveness values current when each phase starts. Standard measures bar diesel idling and staging within 1,000 feet of sensitive receptors. Dust controls come as a short list for grading under 4 acres away from sensitive receptors and an expanded list for larger sites or those within 1,000 feet.

Operational thresholds

Table 3-2, Thresholds of Significance for Operational Emissions Impacts:

The values rest on Health and Safety Code section 40918 and, for DPM, the Carl Moyer Guidelines. Table 3-2's winter CalEEMod instruction applies to the ROG + NOx and DPM rows.

• ROG + NOx. At 25 lb/day or more the project is potentially significant and goes to the district. Table 3-4 applies to combined ROG + NOx or PM10 and scales on-site mitigation: 25 to under 30 lb/day, at least 4 measures; 30 to under 35, at least 8; 35 to under 50, at least 10; 50 or more, all feasible measures. A project GreenPoint rated or LEED certified with third-party verification needs 3, 6, 8 or 12 additional measures, respectively. Measures used for the rating or certification cannot also count toward these totals. Both categories require all feasible measures at or above the annual threshold. At 25 tons per year or more the Handbook requires an EIR, and off-site mitigation if emissions stay above it after all feasible on-site measures.
• DPM. Over 1.25 lb/day, on-site BACT, and a health risk assessment may be required with sensitive receptors within 1,000 feet.
• Dust. Over 25 lb/day or 25 tons per year, permanent dust controls or district-approved off-site mitigation.
• CO. Section 3.5.5 requires modeling above 550 lb/day in a confined or semi-confined space. It also requires CO modeling wherever vehicle activity occurs in a confined or semi-confined space, without attaching that requirement to the mass threshold. A predicted violation of the state standard requires mitigation or redesign.

For projects paying an operational off-site mitigation fee, Section 3.8.3 converts emissions above the daily threshold from pounds per day to tons per year and divides by the daily-to-annual equity ratio of 5.5. That divisor does not apply to exceedances calculated against the annual threshold. The excess annual tons are multiplied by project life and the current Carl Moyer cost-effectiveness value; the footnote adds a 15 percent grant administration fee. Smaller projects can screen out with the updated Table 1-1, which covers operating years 2020 through 2045, or the district's single and mixed-use screening spreadsheet; neither suits heavy diesel or dust-heavy projects, which go to CalEEMod.

Greenhouse gases

The 10,000 metric tons CO2e per year threshold still applies to stationary sources that need a district permit to operate. For new residential, commercial and mixed-use development, the 2012 thresholds of 1,150 MT CO2e per year or 4.9 MT CO2e per service population per year were tied to 2020; the district's August 9, 2023 memo describes a 2015 California Supreme Court decision as invalidating AB 32 thresholds for projects with planning horizons beyond 2020 and recommends a bright-line and an efficiency value for each operating year from 2020 to 2045 (Table 2, printed with "DRAFT" in its title). Either kind may be used. Selected years, with the efficiency row the table adjusts for new development:

The memo applies the test to each project or project phase. Emissions at or below the value for that project's or phase's first operating year represent its fair share toward the SB 32 target if that year is 2030 or earlier, and toward carbon neutrality by 2045 if later. Amortized construction GHG is added, and sectors CalEEMod reports but the county inventory left out, such as refrigerants, are removed before comparing. The district asks lead agencies to adopt Table 2 under CEQA Guidelines section 15064.7, with a policy on which kind applies. A project consistent with an adopted qualified GHG reduction plan is presumed not significant. Excess emissions are mitigated on site first, then by local off-site projects, then by offsets, before the occupancy permit. For the efficiency test, service population means population plus employment. To calculate lifetime offsets, the memo recommends annual CalEEMod runs against each year's applicable threshold until emissions fall below it or the runs cover the project life, then summing the annual excess emissions.

Toxics, odor and other tests

• Ambient standards. A project whose emissions are predicted to cause or add to a violation of any standard is significant; the district says when a project must model.
• Toxics. For a new source near sensitive receptors, a Type A project, excess cancer risk is significant at 10 in a million. Since the California Supreme Court's December 17, 2015 decision in California Building Industry Association v. Bay Area Air Quality Management District, the district no longer requires risk assessments for new receptors near existing sources, though it may recommend disclosing the risk.
• Odor. Table 3-3 screens at 2 miles from a petroleum refinery and 1 mile from the other listed uses, such as landfills, oil fields and wastewater treatment plants. New receptors near an existing source are significant if they would sit as close as any spot with more than one confirmed complaint a year, or three unconfirmed a year, averaged over three years.
• Clean Air Plan. Section 3.2 requires a consistency analysis for program-level review and may require one for project-level review. The analysis compares the proposal with the plan's land use and transportation control measures and strategies.
• Cumulative. The analysis takes in all planned construction within one mile.

What this means for a report

A San Luis Obispo County report calculates construction emissions by day and by quarter and operating emissions by day and by year, compares them with Tables 2-1 and 3-2, and states the mitigation each exceedance brings. Operating ROG + NOx of 25 tons per year or more means an EIR. For GHG, amortized construction plus operating emissions are compared with the Table 2 value for the first operating year of the project or project phase, where the lead agency has adopted those thresholds.

Where the thresholds are published

San Luis Obispo County Air Pollution Control District, CEQA Air Quality Handbook: A Guide for Assessing the Air Quality Impacts for Projects Subject to CEQA Review, 2023 Administrative Update Version to the APCD Board Adopted April 2012 Version, final version, with the 2017 Clarification Memorandum and the October 2016 Policy Updates for Ozone Precursor Mitigation and Type B Health Risk Assessments (Sections 1.4, 1.5, 2.1, 2.3, 2.4 and 3.1 through 3.8; Tables 2-1, 3-2, 3-3 and 3-4). CEQA Greenhouse Gas Thresholds & Guidance for the San Luis Obispo County Air Pollution Control District's 2012 CEQA Air Quality Handbook, August 9, 2023 (Table 2). District web pages Land Use Regulation, Permitting & CEQA and APCD CEQA Handbook; neither shows a modified date.