1-1 The issues regarding health effects from particulate matter are addressed in response to Comment F74.

The comment states that background levels of PM-10 are nearly 100 percent over the state standard. The maximum 24-hour average background (57 micrograms per cubic meter) is actually 14 percent over the standard (see Table 4.5-29 of the DEIR). This measured background level is considerably lower than the Federal standard, which is 150 micrograms per cubic meter (38 percent of the standard), and is less than the new PM-2.5 Federal standard of 65 micrograms per cubic meter. The maximum background level reported on Table 4.5-29 represents the average of the highest second high observed concentrations over the years 1994-1996 at the Arkansas Street station. These maximum levels are 65, 48 and 59 micrograms per cubic meter, respectively.

1-2 The issues regarding secondary particulate matter are discussed in the responses to Comments U14 and U22.

1-3 Please see the responses to Comments U11 and U15.

1-4 Impact 4.5-5 specifically addresses the issue of whether the project would be inconsistent with the regional air quality plan, the BAAQMD’s ’97 Clean Air Plan. The ’97 Clean Air Plan was developed to address the "nonattainment" status of the Bay Area with respect to the state ozone standard. The DEIR concludes that this impact would be significant. Emissions projections from the Potrero power plant were included in the aggregate emissions projections used as the basis for the discussion and analysis of Impact 4.5-5. Please also see the response to Comment U14.

1-5 Please see the response to Comment U31.

1-6 As described on page 3-9 of the Draft EIR, capacity factors used in the report were derived using the SERASYM™ unit-specific, California-wide data set, which was processed by the SERASYM™ production cost model to forecast plant operations. The computer modeling was conducted by Sierra Energy and Risk Assessment, Inc. (SERA), a California company that developed the model and has been running it for more than a decade. In developing modeling assumptions, SERA used the best and most reliable data available to the CPUC during the preparation of the Draft EIR. Tables G-1 to G-20 of Attachment G summarizes this modeling by showing the modeled capacity factors and resultant criteria air emissions for every power plant unit being divested in every scenario that was modeled. Section 4.5 (Air Quality) of the Draft EIR carries these projections forward by analyzing the emissions for the power plants (Impact 4.5-1, beginning on page 4.5-51), analyzing the resulting local concentrations of air pollutants (Impact 4.5-2, beginning on page 4.5-61), analyzing the effect of toxic air contaminants (Impact 4.5-3, beginning on page 4.5-71), and the effect of the project on regional air quality plans (Impact 4.5-5, beginning on page 4.5-77). Some of the detailed analyses conducted actually go beyond the requirements of CEQA, and all analyses satisfy such requirements.

1-7 Please see the response to Comment U21.

1-8 Please see the responses to Comment U23, U24, and U25.

1-9 The atmospheric dispersion modeling analysis for the Potrero Power Plant was conducted using information from an earlier PG&E modeling study of the power plant area. This PG&E study identified numerous sensitive receptors in the vicinity of the plant that represented the nearest local schools, residential complexes, nursing homes, etc., in the local Potrero area. Included in this group of receptors were sensitive sites within the Bayview/Hunters Point area (some 2.5 to 3.5 km south of the Potrero Power Plant). These same sensitive receptors were used for the atmospheric dispersion modeling analysis performed for the DEIR. Model-predicted concentrations of criteria pollutants were developed for these sensitive locations and maximum concentrations from these receptors were analyzed and presented in the DEIR. Since the maximum concentrations for these sensitive receptors were presented, concentrations at all other sensitive receptor locations (including those in the Bayview/Hunters Point area) would be less than the maximum. In fact, a receptor located atop Hunters Point Hill representing the nearby Earl P. Mills Community Center, Growth and Development Center (a child care center), and the Jedediah Smith Elementary School, was determined to be the point of maximum concentration from the atmospheric dispersion modeling analysis performed for this DEIR. Since model-predicted maximum concentrations were less than significant, concentrations at all other sensitive receptors would also be less than significant. Thus, presentation of maps showing concentration gradients is not necessary. Finally, the modeling analysis considered one entire year of hourly meteorological conditions representing a total of 8,760 hours of varying time periods and meteorological conditions.

1-10 Please see the responses to Comments U14 and U16.

1-11 The DEIR identifies a number health effect endpoints from exposure to air pollutants. Some of the health effects from exposure to particulate matter are described on page 4.5-31 of the DEIR. Mortality is one of the effects identified from exposure to particulate matter. The relative risks for particulate matter exposure that were cited in the DEIR show a wide range of values, both for morbidity (health impairment effects) and mortality. However, generally the values for morbidity were higher. This is explained further in response to comments F66 and F74. Since some of the morbidity and mortality relative risks overlapped, the evaluation included both types of endpoints. With respect to the project impacts, maximum contributions of particulate matter emissions to ambient air levels are well below levels determined to cause significant health effects, both mortality and morbidity. The maximum short term increases range from 0.5 micrograms per cubic meter to 3.6 micrograms per cubic meter, which are well below short-term increases that showed measurable health effects in the cited studies.

1-12 The identity of the potential bidders is not publicly known at this time, although identity of the firms that successfully bid on the first round of power plant divestitures provides some insight into the characteristics of the new owners, as described in Attachment C of the DEIR (pages C-19-20). Chapter 5 (page 5-4, last sentence of the first paragraph) of the DEIR does specifically consider the possibility that a new 480 MW plant would be located at or near the Potrero plant site, and the subsequent analysis of environmental impacts presented in Chapter 5 considers that possibility. Repowering Potrero would be essentially the same as locating the new plant at (rather than near) the Potrero site. (In either case, the new 480 MW of generation is assumed to supplement existing generation at Potrero.) Please see the response to Comment U37.

1-13 The EIR preparers are confident that this EIR presents sufficient information for the decision-makers to be fully informed of the environmental consequences of their actions, and for the public to make an independent, reasoned evaluation of the project’s impacts and of the reasoning of the decision-makers. The detailed air quality analysis presented in the DEIR documents the existing pollutant concentrations both in the vicinity of the power plants and in the emissions from the power plants themselves. The discussion both acknowledges and quantifies potential increases in emissions of pollutants that would result from the project. A conservative approach (i.e., one that exaggerates the adverse effects that would occur) was taken in which baseline operations were compared to an Analytical Maximum Scenario where the maximum possible increase in operations would occur under the proposed project. However, for a variety of reasons presented in Section 3.6.2 of the DEIR, it is very unlikely that operations would reach the levels modeled under the Analytical Maximum Scenario. To calculate the projected emissions increases, the dispersion model ISCST3 (Industrial Source Complex Short Term 3, version 97363) model was run. This model is approved and recommended by the U.S. Environmental Protection Agency for estimating potential human health risks associated with facilities where combustion of materials produces residual amounts of pollution that may be released to the environment. As documented in the DEIR, the model results demonstrate that while potential increased operations under the proposed project would result in increased pollutant emissions from the power plants, the increases would not exceed ambient air quality standards or any of the other significance criteria defined on pages 4.5-50 through 4.5-51 of the DEIR. Therefore, the DEIR does not ignore the fact that more pollution will be produced in an area already affected by chemicals in the environment, nor does it attempt to present only information that supports a conclusion of no significant impact; rather, the results of the detailed analysis objectively lead to the conclusion of no significant impact.

1-14 The air quality significance criteria were developed to be consistent with (then current) CEQA Guidelines’ Appendix G, which stated that an air quality impact may be considered significant if it would result in a violation of an ambient air quality standard or a substantial contribution to an existing or projected violation. The revised CEQA Guidelines, released in October 1998, include the same criterion in the environmental checklist. In both cases, the CEQA Guidelines distinguish between substantial contributions (considered to be significant) from non-substantial contributions (considered not significant) to areas where violations of standards already occur.

As an additional point of clarification, the commenter’s observation that 24-hour PM-10 concentrations at the Arkansas Street monitoring station are nearly double the State standard is misleading. Table 4.5-7 of the DEIR indicates that there has been only one sample (93 micrograms per cubic meter) measured in San Francisco over the past five years that could reasonably be described as "nearly double" the state standard of 50 micrograms per cubic meter. The next highest measured concentration over the past five years was a value of 81 micrograms per cubic meter, which is 62 percent above the standard. Over the past five years, approximately 5 percent of the PM-10 samples (16 of 305 samples) exceeded the state standard and approximately one-half of the exceedances (i.e., 7) were within 20 percent of the standard.

The commenter also asserts that there is not enough information in the DEIR to evaluate the significance of emissions of such pollutants as ozone, sulfur dioxide, and carbon monoxide. Each of these criteria pollutants is discussed in the DEIR in Section 4.5, Air Quality, and the State and Federal attainment status of the pollutants in each of the regional air basins in which the plants to be divested are located is discussed. Project emissions of each of these pollutants were modeled along with the other criteria pollutants and the 1999 and 2005 analytical maximum emissions were compared to the 1999 baseline emissions. Project emissions were evaluated according to the significance criteria defined in Section 4.5.4, starting on page 4.5-50. Therefore, information has been provided and the analysis has been conducted in accordance with the requirements of CEQA. It should be noted that some of the discussion in Section 4.5 addresses ozone precursors (ROG and NO_X), rather than ozone itself.