Monterey Bay Air Resources District
The Monterey Bay Air Resources District's CEQA guidance covers the North Central Coast Air Basin: Monterey, Santa Cruz and San Benito Counties. Its thresholds are in the CEQA Air Quality Guidelines, prepared under the district's earlier name, Monterey Bay Unified Air Pollution Control District. They were adopted in October 1995 and revised in February 1997, August 1998, December 1999, September 2000, September 2002, June 2004 and February 2008, and an addendum on acrolein dated July 15, 2008 heads Chapter 9. The preface calls the guidelines advisory and says they set out the district's adopted thresholds of significance. The district's CEQA page links this PDF as its CEQA Guidelines.
Construction
Table 5-1 sets one construction threshold: 82 lb/day of PM10 from direct emissions. Section 5.3 applies it to activities such as excavation, grading and on-site vehicles near and upwind of sensitive receptors, and district-approved dispersion modeling can refute or confirm it: if modeling shows that project emissions, together with existing emissions where present, would not exceed the state PM10 standard of 50 micrograms per cubic meter over 24 hours at existing receptors, the impact is not significant. The table's source line is dated 2000.
Ozone precursors from typical construction equipment, such as dump trucks and bulldozers, are accommodated in the emission inventories of the state and federal air plans and are not significant; Section 7.2 says calculating them is not necessary. Sections 5.3 and 7.2 call for district consultation on other equipment, including grinders and portable equipment.
Table 5-2 turns the PM10 threshold into a screening level, assuming 21.75 working weekdays a month and daily watering; the guidelines say it is not a definitive threshold.
| Activity | Potential threshold |
|---|---|
| Construction site with minimal earthmoving | 8.1 acres per day |
| Construction site with earthmoving (grading, excavation) | 2.2 acres per day |
Operations
Table 5-3, Thresholds of Significance for Criteria Pollutants of Concern, Operational Impacts:
| Pollutant | Threshold of significance |
|---|---|
| VOC | 137 lb/day (direct + indirect) |
| NOx, as NO2 | 137 lb/day (direct + indirect) |
| PM10 | 82 lb/day (on-site); AAQS exceeded along unpaved roads (off-site) |
| CO | LOS at intersection/road segment degrades from D or better to E or F or V/C ratio at intersection/road segment at LOS E or F increases by 0.05 or more or delay at intersection at LOS E or F increases by 10 seconds or more or reserve capacity at unsignalized intersection at LOS E or F decreases by 50 or more; 550 lb/day (direct) |
| SOx, as SO2 | 150 lb/day (direct) |
Unless a pollutant-specific criterion says otherwise, the thresholds apply to all direct and indirect emissions, whether or not the district permits the source: the guidelines say that after Communities for a Better Environment (2002), meeting a district rule no longer shows emissions are not significant. VOC and NOx are each compared on their own: 100 lb/day of direct VOC plus 55 of indirect VOC is significant, while 100 of VOC plus 55 of NOx is not. Chapter 2 traces them to offset levels. Neither Table 5-1 nor Table 5-3 has a PM2.5 row.
The operational PM10 tests cover on-site emissions and exceedances along unpaved roads. Where existing PM10 emissions are present, Section 5.4 calls for modeling project plus existing emissions against the state 24-hour standard at existing or reasonably foreseeable receptors. The CO traffic tests use peak-hour LOS after mitigation; the reserve-capacity test uses the turning movement with the worst reserve capacity. Section 5.4 also covers substantial heavy-duty truck traffic or substantial traffic along urban street canyons or near a major stationary CO source. Any of these calls for CO modeling; if it shows no exceedance, the impact is not significant. Section 7.5 recommends the screening procedure in the Caltrans Transportation Project-Level Carbon Monoxide Protocol, then CALINE4 if needed. A source directly emitting 550 lb/day or more of CO, or 150 lb/day or more of SOx, is significant unless modeling shows no violation of the standards.
Table 5-4, Indirect Sources with Potentially Significant Impacts on Ozone, lists sizes at which a land use could reach 137 lb/day of VOC or NOx before mitigation in the year 2005, from URBEMIS2002 and for illustration only: for example, 810 single family dwelling units or 930,000 sq. ft. of general office.
The negative declaration test
Section 5.6 sets the conditions for a Negative Declaration with the same numbers and tests, and adds that the project violates no other standard, is consistent with the Air Quality Management Plan and has no other significant effect, such as odors. Figure 5-1, the district's checklist, says a yes on any question after mitigation means an EIR must be prepared.
Cumulative impacts and plan consistency
A project inconsistent with the Air Quality Management Plan has a significant cumulative ozone impact unless its emissions are totally offset. The Association of Monterey Bay Area Governments makes consistency determinations for population-related projects, and the district makes all others. For residential projects, the consistency test compares the project's population plus existing population and population from approved but unbuilt projects with the forecast for the next five-year increment covering project completion. Section 5.5 uses the jurisdiction's forecast generally, but countywide forecasts for projects in Monterey County.
Toxic air contaminants and odor
Under Section 9.4, a carcinogen whose emissions can cause a cancer risk greater than one incident per 100,000 population is significant, in construction or operation. Non-carcinogens could be significant above a threshold based on the best available data: the acute (1-hour) or chronic (annual) reference exposure level, with PEL/420 added for operations; the district is to be asked which applies. Operational equipment that complies with Rule 1000 is not significant. A project next to a toxics source not covered by Rule 1000 may also be significant and need modeling. The July 15, 2008 addendum suspended use of the acute acrolein reference exposure level through the end of 2008; it does not establish a continuing exemption.
Odors in substantial concentrations could be significant if they "would cause injury, nuisance, or annoyance to a considerable number of persons or would endanger the comfort, health, or safety of the public." Section 7.3 points to ASTM methods E679 and E1432.
Construction dust practices
Section 8.2 lists the district's feasible PM10 measures, among them watering active areas at least twice daily, stopping grading when wind is over 15 mph, stabilizing areas idle for at least four consecutive days, keeping at least 2 feet of freeboard on haul trucks, and posting a public sign naming who takes dust complaints, with corrective action within 48 hours and the district's number shown for Rule 402 (Nuisance). Table 8-2 rates watering at 50 percent, wheel washers at 50 percent, paving site roads at 90 percent and street sweeping at 34 percent, and says reductions within a source category are not additive.
Greenhouse gases
The 2008 guidelines carry no greenhouse gas threshold. Chapter 12, Climate Change and Assessment of Project Impacts from Greenhouse Gases, holds one line saying the chapter is reserved. The district's CEQA page does not address greenhouse gases.
What this means for a report
Daily pounds are the unit throughout, and each pollutant is compared on its own, VOC and NOx as direct plus indirect. Construction has one mass threshold, PM10. A PM10, CO or SOx finding can be overturned by modeling against the ambient standards; the guidelines offer no such route for VOC and NOx. A yes on the Figure 5-1 checklist after mitigation means an EIR. The thresholds date from the February 2008 revision or earlier, Table 5-4 rests on URBEMIS2002 and the year 2005, and the district's page now recommends CalEEMod (see what CalEEMod is and how to read its report).
Where the thresholds are published
Monterey Bay Air Resources District, CEQA Air Quality Guidelines, prepared as the Monterey Bay Unified Air Pollution Control District, adopted October 1995 and last revised February 2008: Sections 2.2 and 2.3; Table 5-1, Threshold of Significance, Construction Impacts; Table 5-2, Construction Activity with Potentially Significant Impacts; Table 5-3, Thresholds of Significance for Criteria Pollutants of Concern, Operational Impacts; Table 5-4, Indirect Sources with Potentially Significant Impacts on Ozone; Sections 5.3 to 5.6 and Figure 5-1, Checklist for Significance of Air Quality Impacts; Sections 7.2, 7.3 and 7.5; Section 8.2 and Table 8-2, Mitigation Measures, Construction Emissions; Section 9.4; Addendum re Acrolein to Chapter 9, July 15, 2008; Chapter 12, reserved. The district's CEQA page, no modified date shown. The page also links Appendices A, B and C to the guidelines, a CEQA Implementation document and a Consistency Procedure, which this handbook did not open.