Monterey Bay Unified Air Pollution Control District
24580 Silver Cloud Court
Monterey, CA 93940

September 4, 1997

Bruce Kaneshiro, Project Manager
c/o Environmental Science Associates
225 Bush Street, Ste. 1700
San Francisco, CA 94104


Dear Mr. Kaneshiro:

Staff has reviewed the Initial Study and Negative Declaration for the proposed project and has the following comments:

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  1. Mitigation Measures - Section 4.5.a.2 of the Negative Declaration states, "PG&E agrees that the transfer of title for Morro Bay Power Plant will not occur until either Rule 431 or the plant is permit to operate has been modified." This section should reference the Moss Landing Power Plant rather than Morro Bay Power Plant and correct the typo, i.e., "plant is permit".


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  1. Nonattainment Status - Table 4.5.2 should be revised to reflect the following attainment status of the NCCAB:
Pollutant Federal State
Ozone Attainment Nonattainment
Carbon Monoxide


San Benito-Unclassified
Santa Cruz-Unclassified
Nitrogen Dioxide


Sulfur Dioxide Unclassified Attainment
PM10 Unclassified Nonattainment


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  1. 1991 AQMP - Page 4.5.12 should be revised to indicate that the 1991 AQMP was updated in 1994, that the 1994 AQMP addresses attainment of the State ozone standard only, and includes a revised design value which reduced emission reductions needed to achieve the State ozone standard from 30% to 20%. With the revised design value, no additional control measures were needed beyond those adopted between 1991 and 1994.


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  1. Predominant Winds - Page 4.5.19 states that the predominant winds at Moss landing are from the NNW with speeds averaging 4-8 mph. Based on wind frequency data from the Moss West site, obtained during our Moss Landing Air Monitoring study, prevailing winds were from the W, as a result of the day time sea breeze. An important secondary component from the ESE was also evident, largely due to the reverse land breeze or drainage flow which occurs primarily at night. This pattern is consistent with a classical sea breeze/land breeze situation. There was very little occurrence of winds from the NNW. In addition, annual average winds averaged about 8 mph with substantially higher winds during the afternoon when the sea breeze is strongest.


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  1. Capacitance - Page 4.5.19 indicates that in 1993 Units 6 and 7 were utilized together approximately 54.4% of the time. It is not clear how to interpret this statement. In particular, it would be useful to clarify if this figure represents how often the two units operated simultaneously or if it represents simple operational service hours irrespective of load or if it is the combined capacitance factor of the two units, which is related to the plant's capacity to generate steam. The capacitance factor is more useful because it indicates how close to generating capacity the units were actually operating during a given period of time.


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  1. County Level Comparisons - In Table 4.5.5, emissions from the Moss Landing Power Plant (MLPP) are compared to those of Monterey County alone. For air basin planning purposes, emissions for important categories are generally compared to the totals for the entire air basin, which in the case of the North Central Coast Air Basin, also includes Santa Cruz and San Benito Counties.


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  1. Mobile Source Inventory - In Table 4.5.5, annual criteria emissions for mobile sources in Monterey County are presented and are then compared with 1993 emissions from the MLPP. In comparing these figures with Monterey county mobile source emissions presented in the 1993 Emission Inventory, published by the Air Resources Board in June of 1995, it appears that the emission figures for on-road motor vehicles were based on an older version of the on-road vehicle emission estimation model. The model that was current in June of 1995 was known as EMFAC7F1.1. Emission estimates from the current model (MVEI7G) are significantly higher which could affect the comparisons, particularly for NOx.


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  1. Natural Emissions - Emissions estimates for natural sources presented in Table 4.5.5 appear to be significantly underestimated. Again in comparing these figures with ARB's published 1993 Emission Inventory, it appears that the natural source figures are based on an incomplete total which only includes wildfires. Had the other sub-categories been included, particularly biogenic wildfires. Had the other sub-categories been included, particularly biogenic ROG emissions from vegetation, the totals would be substantially higher. Since this category appears to be incomplete, it would probably be best to completely omit it from the table.


Thank you for the opportunity to review the document. Please do not hesitate to call if you have any questions.


Janet Brennan
Supervising Air Quality Planner
Planning and Air Monitoring Division


c: Nicolas Papadakis, AMBAG
Fred Thoits, MBUAPCD
Bob Nunes, MBUAPCD