Although the EIR identifies a potential for increased operation of the Potrero Power Plant, the electric generating steam boiler (Unit 3) will continue to use natural gas exclusively as a fuel (as required by Regulation 9, Rule 11 since 1995), which is the cleanest burning of the fossil fuels (see DEIR page 4.5-1), and the predominant winds blow the emissions out over the bay. Please see also responses to Comments 4-2 and F70.

Please see response to Comment F30 regarding the suggested mitigation measures for limiting Potrero plant operations and/or obtaining air emission credits.

Finally, with respect to the commenter’s main concern about potential health effects related to particulate emissions (i.e., PM-10), some studies have indicated that any incremental increases in PM-10, such as during particular 24-hour periods when the ambient air already exceeds PM-10 standards, can cause health impacts. An in-depth study of those potential effects is not believed to be necessary or appropriate for review in this EIR, but may be necessary or appropriate in connection with reviews of environmental and community impacts of any development or expansion plans for these or other power plant sites. In addition, the purchase and sale agreement for these plants requires the owner to consult in good faith with the City and County of San Francisco about the impacts of any planned expansion or development of the Potrero Power Plant site.

Detailed responses to the commenter’s concerns regarding potential health effect issues are provided in responses to Comments F62, F63, F66, F67, F68, F73, and F74.

F2 Table S-3 (page S-13 in the DEIR) shows that the EIR assumes that the Pittsburg District Energy Facility (PDEF) will be on line by 2005 (as analyzed in Cumulative Variant 2) and that another new power plant in San Francisco will also be on line by 2005, either a new 480 MW power plant (analyzed in the primary cumulative impacts analysis) or a new 240 MW power plant in San Francisco, together with a new transmission line (under 2005 Cumulative Variant 1). It was considered too speculative to determine more precisely the year in which these plants would first be on line. The timing of plant retirements that are assumed to occur under various scenarios can be determined from data presented in Table 5.2 (see pages 5-17 and 5-18 of the DEIR).

As indicated in Chapter 5 (page 5-3) of the DEIR, it appears reasonably foreseeable, in light of the June 9, 1998 agreement between PG&E and the City and County of San Francisco, that generation and/or transmission facilities to serve the City of San Francisco and replace the Hunters Point Power Plant would be in place by 2005. Footnote 1 (page 5-3) explains that, since permitting for new generation or transmission facilities normally takes about two to three years and construction of new facilities requires approximately two years, it is reasonable to forecast that such activities would be complete by 2005. However, as footnote 1 also explains, it is possible that the Hunters Point Power Plant will not have closed precisely by 2005, in which case it is presumed that PG&E would continue to operate the Hunters Point plant at the minimum level necessary for reliability purposes, until the conditions necessary for closure of the plant were satisfied. As noted, the cumulative impacts analysis of the DEIR does not depend on the projects assumed within it having occurred by any particular year. If the Hunters Point plant were to be replaced by 2007 rather than 2005, for instance, the analysis would remain valid and applicable.

F3 The commenter suggests that tables (G-1 to G-20) in Attachment G should include notes as to where in the DEIR the data are used. This would be a very time consuming and complex process since these tables are used as background or supporting data in varying ways and in many places throughout the DEIR. However, for the sake of clarity, the following changes are hereby added:

To Table S.1 (and Table 3.1) the title is changed as follows:

And the following footnote is added:

To Table S.3 (and Table 5.2) the title is changed as follows:

And the following footnote is added:

To Table S.5 (and Table 6.1) the title is changed as follows:

And the following footnote is added:

Information in Tables S.4 and S.6 is not directly correlated to the tables found in Attachment G. Therefore, Tables S.4 and S.6 remain unchanged.

F4 Please refer to the responses to Comments F53 and F61.

F5 Except for the unique differences being analyzed in Alternatives 2A and 2B (as explained on pages 6-16 and 6-17 of the DEIR), the underlying assumptions and data for the Year 2005 (Alternatives 2A and 2B) are the same as for the 2005 Cumulative Scenario, as described on pages 3-3 and 3-13 of the DEIR and also in Attachment G, pages G-7 to G-9.

F6 The environmental impacts associated with Alternative 2B (no bundling of plants for sale) would generally be increased over those of the project, and not decreased as indicated by the commenter. The environmental impacts of Alternative 2A (bundling the fossil-fueled plants for sale) would be decreased compared with the impacts of the project to the extent that the magnitude of the project’s impacts are based on the potential for plant operation levels to rise under divestiture. This is because the tendency of new owners to generate more electricity than PG&E would be somewhat reduced under Alternative 2A compared to the project as proposed. (Please see page 6-16, third paragraph, of the DEIR for a more detailed explanation of this.) As an example, because it is assumed that power generation under Alternative 2A would be less than under the proposed project, there would be less change in the use of water resources by the plants and discharges into receiving water bodies would be less, resulting in reduced impacts to water quality and temperature and to aquatic biological resources. Similarly, decreased operations under Alternative 2A could result in reduced noise levels in the vicinity of the plants compared to the project. The precise amounts by which the impacts of Alternative 2A may be lessened in comparison to the project is not quantifiable. The analytical maximum capacities of the plants are the same under both the project and Alternative 2A; the implementation of Alternative 2A would merely lessen the likelihood that the plants would operate at such capacities. All of the impacts of Alternative 2 are discussed in Section 6.4 of the DEIR, pages 6-9 through 6-28. The discussion on page S-16 referenced in the comment is intended as a brief summary of Section 6.4. For additional details on impacts of the alternatives, the reader is referred to that section.

Regarding the phrase "the levels of significance of the impacts would be identical," this means that while the magnitude of impacts under Alternative 2A would be reduced, the significance level identified for each project impact would be the same under the alternative. In other words, while the impacts to water quality, for example, would be less under Alternative 2A than under the proposed project, the impact would be less than significant for both the alternative and the project. Table S.6 of the DEIR illustrates this relationship between the project and each alternative for all impacts identified in the environmental analysis.

F7 Please see response to Comment F30.

F8 As discussed in the response to Comment F6, Table S.6 of the DEIR illustrates the comparative magnitude of impacts between the proposed project and the project alternatives. The "L" indicates that the magnitude of the impact under the alternative would be less than under the project. Conversely, a "G" indicates that the impact would be greater under the alternative. Table S.6 is intended only as a summary/overview of the impacts of the project and alternatives. Substantial details on the impacts are provided in Chapter 4 for the project and in Chapter 6 for the alternatives.

F9 In order to reflect the City’s comment and for clarification, Figure 4.1-1 (page 4.1-3) and Figure 4.1-4 (page 4.1-8) are hereby amended as follows: The property boundary around the site will no longer include the pipeline to the Pier 70 Marine terminal and the terminal from the Potrero plant site. Please see the revised Figures 4.1-1 and 4.1-4 below. The commenter is correct that the lease (which is included in the sale) must be transferred by PG&E to the new owner, subject to approval by the Port of San Francisco.

F10 The significance criteria listed in Section 4.4.3 are all of the water resources related criteria from CEQA Appendix G. The water resources changes associated with the project are from the potential operation of the plants at higher levels and from construction of minor facilities such as access roads and fences. The nature of the project is such that there would be no impacts to flooding and stormwater runoff quantity (effects on stormwater quality from construction is discussed). The environmental setting and effects on public water supplies are discussed in Section 4.12, Utilities and Service Systems. The setting for water quality, most importantly the NPDES permit limits and groundwater, are described in Section 4.4.2.

F11 There are no project-related impacts on groundwater at the Potrero plant. Changes in cooling water use would not affect groundwater, since the water is taken from, and discharged to, Lower San Francisco Bay. Construction of the minor facilities or the remediation of soils may require groundwater dewatering. Any water quality concerns from these activities would be addressed in complying with the required permit conditions.

F12 The DEIR contains descriptions of the discharge sources and the types of chemicals discharged from these sources in Section 4.4.2. A summary of the NPDES permits is provided in Section 4.4.1; the new owners would be required to comply with the existing permit conditions.

F13 The significance criteria listed on page 4.4-13 of the DEIR are hereby amended as follows:

F14 CEQA requires an EIR to focus on the significant or potentially significant effects of a project. The project would not result in substantial flooding, contamination of a public water supply, or any of the other occurrences identified as significance criteria in Section 4.4.3. It is therefore not required and it is unwarranted in the interest of conciseness (also mandated by CEQA) to include a series of impact statements declaring that no impact on flooding, water supply, etc. would occur with implementation of the project. Similarly, it is also unnecessary to provide separate impact statements and discussions for each of the power plants when the impacts identified and the discussions supporting them apply to each of the plants.

F15 Impact 4.4-2 on page 4.4-15 is hereby amended to add the following after the fourth paragraph:

F16 Given the way the DEIR is organized, the information related to groundwater contamination at the Potrero Power Plant is all in Section 4.9, Hazards, so the appropriate cross reference would be to that section. The following sentence is added to the DEIR at the end of the first paragraph on page 4.4-1.

F17 The DEIR assumes that the Hunters Point Power Plant would be operating only to meet reliability. The commenter is correct that such operational regime is consistent with Version C of the Must Run Agreement.

F18 On October 8, 1998, the CPUC issued Decision 98-10-029, which approved the agreement between PG&E and the City and County of San Francisco regarding the Hunters Point Power Plant. This agreement is summarized within the second complete paragraph on page 1-4 of the DEIR. The DEIR analysis is consistent with the terms of the agreement. Please see response to Comment F20 regarding DEIR assumptions with respect to future Hunters Point plant operations.

F19 On page G-6 of Attachment G, the following statement is made:

During visits to each of the power plants during the winter and spring of 1998, the EIR preparers confirmed that the Proposed Retrofit Technology shown in Table B-2 of PG&E’s Fossil Plant PEA was already installed or would be installed during 1998, and would be operable on each specified unit no later than January 1999.

It is noted that emissions estimates can be presented in various forms, such as tables or charts. The DEIR used the former, while the commenter requests that the former be supplemented with the latter in the Final EIR. Either form is adequate; thus, no supplementary charts have been prepared. However, since all comment letters become part of the Final EIR, the particular charts prepared by the commenter will become part of the Final EIR.

F21 As discussed in the DEIR in the third paragraph on page 4.5-61, the project was found to cause some increase in emissions of criteria pollutants relative to existing and baseline cases. It is also noted in the same paragraph that these emissions are covered by existing air permits with the local air pollution control district. These existing permits already require the operator of a pollution source to both monitor its emissions and regularly report those emissions to the permitting agency. It is primarily by these means that these agencies ensure compliance of permitted sources with applicable air quality standards. These emissions data are available from these agencies for public review. The commenter expresses concern that actual emissions from the sources might exceed those stated in the DEIR and seeks some means of ensuring that this not occur. Since two of the fundamental bases for the analysis of air quality impacts from the project are that the Analytical Maximum capacities represent very conservative measures of potential future plant operations and that the sources could and would not exceed their permitted emission levels, this by itself assures that actual emissions would not exceed those stated in the DEIR.

F23 The DEIR did consider special circumstances for significance criteria. Even though the power plants proposed to be sold would continue to be governed by existing air quality permits, and would operate within the parameters of such permits, the EIR did not assume that compliance with all regulations would automatically mean that the project’s impact on air quality was less than significant. Particularly in light of agency and community concerns over air emissions and potential health impacts, the five significance criteria shown on page 4.5-50 and 4.5-51 were used to analyze the air quality effects of the project.

F24 Significance criterion #1 on page 4.5-50 of the DEIR distinguishes between two different circumstances. Under circumstances where the background concentration of a given pollutant is less than the corresponding ambient air quality standard, the ambient air quality standard itself becomes the significance criterion. Under circumstances where the background concentration of a given pollutant is greater than the corresponding ambient standard, a concentration-based threshold identified under Prevention of Significant Deterioration (PSD) provisions is used as the significance criterion. In the Bay Area, the second circumstance applies to PM-10. (Note that standards for ozone are also violated in the Bay Area, but PSD provisions do not contain an ozone threshold. This is because ozone is evaluated in a fundamentally different way using emissions estimates rather than dispersion modeling techniques. It should also be noted that PSD provisions do not directly apply to the project because the project would not require the power plants to apply for new air quality permits. Specific PSD provisions are used to provide a quantitative basis for evaluating qualitative significance criteria listed in the CEQA Guidelines.)

Under the second circumstance, PSD concentration-based thresholds were used as the significance criteria, because such thresholds provide the basis for evaluating dispersion modeling results (which are also defined in terms of concentrations). PSD provisions are included in BAAQMD Regulation 2, Rule 2, which is known as New Source Review (NSR). NSR also includes emissions-based criteria (e.g., pounds per day), but such criteria cannot be directly compared to concentration estimates.

The DEIR does, however, cite additional significance criteria, some of which are emissions-based. Significance criterion #2, for example, cites the BAAQMD-recommended emissions-based criteria for evaluating the significance of emissions increases from indirect sources. The BAAQMD CEQA Guidelines distinguishes between indirect sources, such as autos and trucks, which do not operate under BAAQMD permits, and direct sources, like power plants, which generally do operate under BAAQMD permits (BAAQMD, 1996). The emissions-based criteria cited as significance criterion #2 apply to indirect sources, not to direct sources. The DEIR air quality analysis adopts the BAAQMD approach.

Finally, page 4.5-51 of the DEIR describes significance criterion #5, a criterion developed specifically for this DEIR to address the issue of "nonattainment." It achieves this purpose by linking power plant emissions changes to corresponding emissions forecasts contained in the BAAQMD’s ’97 Clean Air Plan. The ’97 Clean Air Plan was prepared specifically to address regional "nonattainment" for the state ozone standard, but it also contains PM-10 emissions forecasts and control measures that would address PM-10 concerns as well (BAAQMD, 1997).

F25 The concentration-based PM-10 significance thresholds cited in the discussion of significance criterion #1 on page 4.5-50 of the DEIR were derived from BAAQMD Regulation 2, Rule 2, paragraph 2-2-233 (Significant Air Quality Impacts, PSD).

F27 Please see responses to Comments U14 and U22.

F29 The commenter makes a valid point. The DEIR is revised to eliminate the idea that the cumulative impact can be presumed to be less than significant because the project-specific impact would be less than significant. However, the conclusion of "less than significant" is rooted in other bases. For example, the DEIR on page 4.5-75, first full paragraph, cites the Mission Bay SEIR, which notes that no authoritative regulatory body has adopted any standard to determine whether the risks posed by existing levels of toxic air contaminants should be considered acceptable and, in turn, whether cumulative increases in ambient risks should be considered significant. Without a scientifically accepted methodology or criterion, a conclusion regarding significance of the cumulative impact would be speculative. Some of the difficulty related to determining cumulative toxic effects relates to the methodology of determining Maximally Exposed Individual (MEI) locations and exposure levels for individual projects. This methodology is not practical for a future scenario with multiple regional stationary and mobile sources.

The lack of a criterion for evaluating cumulative air toxics impacts contrasts with criteria air pollutants (e.g., ozone, carbon monoxide, and nitrogen dioxide). With criteria air pollutants, both project-specific and cumulative impacts can be evaluated with reference to particular values, known as ambient air quality standards, since those values represent concentration levels below which public health and welfare effects can be presumed to be negligible. In contrast, the project-specific air toxics criterion of "10 in a million" risk does not represent a "safe" level where public health and welfare effects can be presumed to be negligible, but rather, the "10 in a million" criterion represents a policy decision by the air district as to the circumstances under which it will require emissions control technology of individual stationary sources. In addition, another possible source of cumulative air toxics criteria is the state’s Air Toxics "Hot Spots" Information and Assessment Act (AB 2588), Under AB 2588, commercial and industrial facilities emitting air toxics were required to prepare toxics emissions inventories, and based on those inventories, certain of those facilities were required to prepare health risk assessments. Based on the results of the health risk assessments, facilities were placed in one of three categories if their calculated risks exceeded 10 in a million: Level 1 (between 10 and 100 in a million risk), Level 2 (between 100 and 500 in a million risk), and Level 3 (greater than 500 in a million risk). For facilities whose risk levels are calculated to be less than 10 in a million, no formal public notification measures were required; thus, the criterion of 10 in a million is a benchmark under state law to distinguish among facilities on the basis of air toxics. But, once again, it is noted that health risk assessments prepared under AB 2588 are facility-specific and that the categorization is made of each facility individually, not to a group of facilities in a given area on a cumulative basis. As such, the "10 in a million" criterion does not lend itself to cumulative air toxics impact assessment.

Also, it is noted that the project’s contribution to the cumulative impact would not be cumulatively considerable. This can be demonstrated by comparing the ambient background risk with the Potrero Power Plant’s contribution at the maximally exposed individual (MEI) location. The average background risk from toxic air contaminants was estimated by BAAQMD to be 303 in a million in 1995 (see page 4.5-12 of the DEIR). Eliminating the Potrero plant entirely would reduce the background risk at the MEI location by only 0.2 to 0.3 in a million (see Table 4.5-34 on page 4.5-73 of the DEIR), which essentially would leave the background risk unchanged. Recent changes to the CEQA Guidelines support the conclusion that such a contribution would not mean that cumulative impacts associated with the project would be significant. Paragraph (a)(4) of Section 15130 of the CEQA Guidelines now states that an EIR may determine that a project’s contribution to a significant cumulative impact is de minimus and thus is not significant. A de minimus contribution means that the environmental conditions would essentially be the same whether or not the proposed project is implemented. As explained above, with or without the Potrero Power Plant, the risk from toxic air contaminants in ambient air in the vicinity of the plant would be expected to be on the order of 303 in a million and, therefore, the project’s contribution would be de minimus.

Page 4.5-75 of the DEIR (first full paragraph) is hereby revised as follows:

In addition, the following paragraph is hereby added after the third full paragraph on page 4.5-74 of the DEIR:

F30 The commenter suggests that additional mitigation measures (e.g., restricting operating hours or requiring air emission offsets) be included in the Final EIR to ensure that air quality impacts will be less than significant. Subsequent to submission of this comment letter, the commenter provided another letter addressing this same issue (see Comment F79). That later, clarifying correspondence requested "a discussion of mitigation measures, to the extent such measures are available or appropriate," and specifically deferred to the CPUC’s responsibility to make the determination of whether any additional "mitigation measures are necessary or appropriate." As indicated in the discussion below, it does not appear that such potential additional mitigation measures are necessary or appropriate because they are not needed to address environmental impacts and/or are otherwise infeasible.

As noted in the comment, the DEIR identifies Impact 4.5-5 (inconsistency with the ’97 Clean Air Plan) as a temporary unavoidable significant impact. Mitigation Measure 4.5-5 would eliminate the inconsistency by 2003. Mitigation Measure 4.5-5 is consistent with the strategy identified by the BAAQMD in Comment Letter E (see the second paragraph of page 1 of its letter dated September 23, 1998). The letter indicates that the BAAQMD is committed to modifying its Regulation 9, Rule 11 so that the rule will continue to apply to these power plants, regardless of ownership. The intent of the modification would be to achieve NOX reductions at least equivalent to the current rule, with the same emission limits and deadlines as the current system-wide schedule. The modification on oil burning (to minimize PM-10, PM-2.5, and toxic emissions) would be retained.

Limiting operating capacities has been considered for mitigating project effects, but as explained in some of the points below, such limitations would not be necessary or appropriate. Acceleration of the Regulation 9, Rule 11 schedule for NOX emission rate reductions has also been considered, but has been rejected for the reasons given below. Based on many considerations, the EIR has determined that more restrictive limitations are not warranted to address the temporary inconsistency with the ’97 Clean Air Plan that would result if the plants operated at their Analytical Maximum capacities. The following points further elaborate on reasons (including policy, cost, schedule, technical and legal issues) that further mitigation (beyond that identified in Mitigation Measure 4.5-5) is not considered feasible.

F32 The commenter refers to the 2015 cumulative analysis for carbon monoxide presented in the DEIR. Such analysis was prepared in response to a request by City and County of San Francisco staff to analyze that year as an extension of the (2015) cumulative analysis presented in the Mission Bay SEIR. With respect to concentration estimates, the Mission Bay SEIR evaluates only carbon monoxide, not the other criteria air pollutants, and thus, the extension of that evaluation in the DEIR evaluates only carbon monoxide.

The DEIR’s analysis year for cumulative effects, with the exception noted above, is year 2005. Please see Tables 4.5-29, 4.5-31, and 4.5-32 and the corresponding discussion on page 4.5-70 of the DEIR for an evaluation of cumulative (2005) concentrations of criteria air pollutants, including carbon monoxide, nitrogen dioxide, sulfur dioxide, PM-10, and PM-2.5. The tables mentioned above were prepared with a method designed to account for mobile and stationary sources of air pollution. As explained in footnote "a" in these tables, a conservative background concentration is assumed for the criteria air pollutants by using the 2nd highest value recorded over a three year period at a BAAQMD monitoring station. These values are actual measured values of recent outside air that include air pollutants from all sources. The 2005 cumulative project increment is then added to these background levels. The 2005 cumulative project increment added is for the stationary sources at the power plants because the mobile sources from the power plants are already accounted for in the current background used to project the future background and Section 4.6 (Transportation and Circulation; page 4.6-2) of the DEIR found that possible increases from the project would be negligible in comparison to existing traffic volumes. The inclusion of other cumulative mobile and stationary source emissions in 2005 is accounted for by the conservative nature of the future background concentrations that are used. There is no information to indicate that other future projects would result in creating higher 2005 background levels than are forecasted in the EIR, and, for the most part, criteria air pollutant levels seem to be trending downward in the regions being analyzed.

F33 PG&E’s contractor, Fluor Daniel GTI, has completed a Phase II Environmental Site Assessment and Risk Assessment for each plant to be divested, including the Potrero Power Plant. The findings of the Phase II Environmental Site Assessment and Risk Assessment for the Potrero Power Plant are summarized here. Results of the Phase II Environmental Site Assessment and Risk Assessment for the Geysers Power Plant are summarized in the response to Comment T10. Findings of the Phase II Environmental Site Assessment and Risk Assessment for the Pittsburg and Contra Costa Power Plants are summarized in the staff-initiated text changes in Chapter 4 of this document.

Page 4.9-6 of the DEIR (second complete paragraph) is hereby revised as follows:

The findings and conclusions of the Phase II investigations do not modify the analysis nor conclusions of the DEIR. However, page 4.9-6 of the DEIR (following second complete paragraph) is amended as follows to reflect the information presented in Fluor Daniel GTI’s Phase II Environmental Site Assessment for the Potrero Power Plant:

Refer to Comment F36 for the proper Phase II reference citation.

F34 Page 4.9-1 of the DEIR (paragraph 1) is hereby revised as follows:

Page 4.9-3 of the DEIR (at end of Regional Setting) is hereby amended with a new paragraph as follows:

As the commenter noted, summaries of environmental conditions at each plant were not included in the Regional Setting section of the DEIR. These summaries are instead provided individually in the Local Setting, Section 4.9.2. For the Potrero Power Plant, the discussion of local environmental conditions begins on page 4.9-3.

According to information presented in the Phase I Environmental Site Assessment for the Potrero Power Plant, the plant site currently has no underground storage tanks. (This information can be found on page 5-11 of the Phase I report.)

The presence of subsurface PAHs at the Potrero plant site is known and was mentioned in the DEIR on page 4.9-5 (bottom paragraph), and again on page 4.9-6 (second full paragraph). PAHs were reported in the Phase II Environmental Site Assessment report for the Potrero Power Plant, as is described in the response to Comment F33.

F35 The presence of asbestos-containing materials and PCBs at the Potrero Power Plant had been noted as "material recognized environmental conditions" in the Phase I Environmental Site Assessment for the Potrero Power Plant. This was mentioned on page 4.9-6 (second full paragraph) of the DEIR. Asbestos-containing waste and PCB-containing waste at the Potrero Power Plant are handled according to existing hazardous waste regulations. For a discussion of the findings of the subsequent Phase II Environmental Assessment, please refer to the response to Comment F33.

For a discussion of lead-based paint, please see the response to Comment F47.

Electromagnetic fields are discussed separately as Impact 4.9-6 of the DEIR, which is found on page 4.9-24.

F36 Page 4.9-25 of the DEIR is hereby amended with the following additional reference:

Also please see the response to Comment F33.

F37 No remediation schedule for the Potrero Power Plant site has been set as yet.

F38 The PEA done by PG&E for the Potrero Power Plant discussed hazardous materials and potential site contamination at the plant site. (This discussion can be found on pages 4-85 through 4-87 of the PEA.) Pertinent information presented in PG&E’s PEA regarding hazards is included in the DEIR in the discussion of potential site contamination beginning on page 4.9-5. The PEA found that the site does not pose any current hazards to human health or the environment.

F39 The current status of the "material recognized environmental conditions" at the Potrero Power Plant remains as described in the DEIR on page 4.9-6. For a discussion of site information presented in the subsequent Phase II Environmental Assessment, please refer to the response to Comment F33.

F40 PG&E performed the Phase II Site Assessment and the Risk Assessment for the Potrero Power Plant site voluntarily. The relationship between the Phase I Assessment, Phase II Assessment and Risk Assessment is discussed in the DEIR on page 4.9-15 (third paragraph). PG&E was not directed to prepare these documents by a regulatory agency.

The need for site cleanup on the basis of risks to human health or to the environment is to be determined by the findings of the Risk Assessment, as is described in the DEIR, page 4.9-17. This Risk Assessment has now been completed, as is discussed in the response to Comment F33. Cleanup would be done in accordance with remediation plans drawn up by PG&E’s remediation contractor, in consultation with the San Francisco Department of Public Health and the San Francisco Bay Regional Water Quality Control Board. A timetable for cleanup would be prepared at that time.

F41 Environmental contaminants are known to be present at the plants to be divested, but cleanup of contamination on private property is required by government agencies only if, in the judgment of those agencies, the contaminants pose a threat to site occupants, to public health, or to the environment. At present, such conditions do not occur at the Potrero Power Plant or at any of the other plants to be divested. Divestiture, therefore, is the primary process that is promoting accelerated cleanup at these plant sites.

Divestiture is expected to accelerate remediation because site cleanup has been factored into, and is an integral part of, the divestiture process. PG&E has been planning for remediation since the divestiture process was initiated. The Phase I and Phase II Environmental Site Investigations have been completed and published, remedial options have been developed and are under discussion, and funds have been set aside by PG&E to pay for the cleanup. All of these actions were taken with divestiture in mind. PG&E has assumed responsibility for legally required remediation of all existing areas of contamination at the plants, as is discussed in the DEIR starting at the bottom of page 4.9-16.

Please also see the response to Comment F42.

F42 The California Environmental Protection Agency (Department of Toxic Substances Control) or the San Francisco Department of Public Health could require site remediation if either agency determined independently that conditions at the Potrero Power Plant posed a threat to public health or to the environment. The San Francisco Bay Regional Water Quality Control Board could require site remediation if it determined that conditions at the Potrero Power Plant posed a threat to water quality. The Department of Toxic Substances Control is currently overseeing the Potrero plant site with respect to environmental issues.

Other laws, ordinances, and regulations, including asbestos regulations, lead-based paint regulations, San Francisco’s Maher Ordinance, the City’s underground storage tank regulations and so on, control the scope and extent of cleanup work at active project sites, but do not trigger site remediation per se.

Should PG&E’s Risk Assessment and subsequent agency discussions determine that site remediation is warranted at the Potrero Power Plant, the "Site Designation Process Under the Unified Agency Review of Hazardous Material Release Sites" would be used to guide the process. This is described on page 4.9-17 of the DEIR (top paragraph).

Also please see the response to Comment L36.

F43 The divestiture process has included the identification of site contamination as part of due diligence, as witnessed by the Phase I Environmental Site Investigation, the Phase II Environmental Site Investigation, and the Risk Assessment. The findings of the Phase II report and Risk Assessment for the Potrero Power Plant are summarized in the response to Comment F33. Under terms of the Purchase and Sale Agreement, PG&E has agreed to be responsible for any legally required remediation of existing contaminated soil and groundwater at the divested plants and therefore will be financially responsible for such remediation activities. Current "must-run" provisions will be considered in remediation planning. The determination of which particular remediation strategies will be ultimately pursued, and how such strategies relate to system reliability, will not be affected by divestiture. The issue of how remediation activities are carried out while system reliability is maintained will need to be addressed regardless of who owns the Potrero Power Plant when such activities are undertaken.

F44 The current situation at the Potrero Power Plant regarding site contamination was described in the DEIR starting on page 4.9-5. Supplementary information generated by the Phase II Environmental Site Assessment is summarized in the response to Comment F33, above.

This setting information indicates that the Potrero plant site does have areas of contamination, and that those areas have been contaminated for years. Although PG&E has accepted responsibility for cleanup of existing contamination, PG&E would have little incentive to accelerate environmental cleanup without divestiture. Even though the Department of Toxic Substances Control is overseeing the Potrero plant site with respect to environmental issues, PG&E is currently under no regulatory mandate to perform remediation.

With regard to costs, all funds necessary to perform remediation would be set aside in advance through the divestiture process. The fact that PG&E has accepted responsibility for site cleanup means that the new owners will not have to pay any of the remediation costs for soil and groundwater contamination existing prior to sale. Divestiture would not create any new potentially responsible parties as to existing contamination.

Divestiture is expected to promote timely and efficient site remediation. The Phase I and Phase II investigations were driven by the divestiture process. Please refer to the response to Comment F41 for further elaboration on why divestiture will promote remediation.

Regarding possible loss of access to records, all environmental documentation is being provided to bidders as well as to interested public agencies, thus divestiture is not expected to result in "loss of access to records," as stated by the commenter. Under Mitigation Measure 4.9-3, PG&E will provide to the new owner copies of all safety-related documentation. Although the new owners will be responsible for ensuring that their operations are in compliance with applicable laws, this informational material may assist new owners in understanding worker health and safety issues and procedures and in meeting all safety and legal obligations regarding hazardous materials handling, emergency plans and storage. For further clarification, the bolded Mitigation Measure 4.9-3 that appears on page 4.9-21 of the DEIR, and in Table S.2 on page S-36 of the DEIR, is hereby revised as follows:

Because the above information is now reflected in the mitigation measure statement, the first sentence of the first full paragraph on page 4.9-21 of the DEIR is hereby deleted.

F45 The commenter is concerned that "PG&E’s proposed responsibility for cleanup could be transferred, diluted, or avoided as a result of the divestiture unless PG&E enters into binding remediation commitments prior to sale."

Each purchase and sale agreement for the plant sites will specify all cleanup provisions for which PG&E is assuming responsibility. Each purchase and sale agreement will be reviewed by the CPUC prior to its approval of the sale, ensuring that PG&E’s commitments to remediation will be spelled out in the agreement and understood by all parties involved, and will be enforceable.

The CPUC review process will ensure that PG&E complies with the environmental responsibilities. Remediation will be done by PG&E under full regulatory agency oversight. As is described on page 4.9-17 of the DEIR, the appropriate lead agency at each plant would be selected by means of the "Site Designation Process Under the Unified Agency Review of Hazardous Material Release Sites." Moreover, Mitigation Measure 4.9-1 requires PG&E to provide to the CPUC written evidence that the Risk Assessment has been provided to not only the buyer of the plant, but to the Department of Toxic Substances Control, the local county health department, and the relevant Regional Water Quality Control Board (RWQCB).

Also, please see the response to Comment F41.

F46 Page 4.9-19 of the DEIR (first bulleted paragraph) describes the properties of petroleum-based products; the paragraph is hereby revised as follows:

Page 4.9-20 of the DEIR (bulleted paragraphs) is hereby amended to include the following:

See the response to Comment N47 for additional amendments to page 4.9-20 of the DEIR.

F47 The commenter expresses concern regarding the presence of lead-based paint at the Potrero Power Plant. Lead-based paint is no longer used at the plant, but some surfaces are still coated with lead-based paint that was applied years ago. Lead-based paint can therefore be considered a potential site contaminant.

Page 4.9-6 of the DEIR (middle of the page, at the end of the Potential Site Contamination section) is hereby amended as follows:

F48 As is described on page 4.9-21 of the DEIR, PG&E intends to provide the new owners with all of PG&E’s nonprivileged informational materials and training documents regarding worker health and safety, emergency plans, and hazardous materials handling and storage. This disclosure will be made during the bidding process.

The commenter has misunderstood the "three day" provision of Mitigation Measure 4.9-3. The requirement "at least three business days prior to transfer of title" that is specified in the mitigation measure refers only to the disclosure form to be signed by the new owner documenting that the mitigation has been performed as required.

Furthermore, as is described on page 4.9-21 of the DEIR, PG&E personnel will continue to operate the divested plants for two years after the sale, which would give the new owners ample time to familiarize themselves with the documents.

F49 The issue that concerns the commenter—proper disposal of hazardous waste generated by remedial activities—would be covered in the Site Remediation Plan that guides each cleanup. The Site Remediation Plan would be subject to review by the lead agency. Divestiture would act to accelerate the process of remediation, but would not change the amount of waste that would ultimately result from any remediation.

Page 4.9-17 of the DEIR (first full paragraph, first sentence) is hereby revised as follows:

F50 The nature and significance of electromagnetic fields, including a summary of CPUC policy regarding this issue, are discussed in the DEIR under Impact 4.9-6 on page 4.9-24. Electromagnetic fields are not power plant "emissions." As is discussed in the DEIR, the existence of electromagnetic fields generated by electrical equipment does not constitute a significant project impact that would require mitigation. The reduction of EMF field using no- and low-cost methods as proposed by the commenter is applicable to newly constructed or upgraded utility facilities. The divestiture of the power plants does not include new or upgraded facilities

F51 The list of projects presented in Table 5.1 was originally provided by PG&E on April 2, 1998. Within a week prior to publication of the DEIR, each of the planning jurisdictions, including the San Francisco Planning Department, were contacted to update the list. Consequently, Table 5.1 was up to date as of publication time. In response to the comment, the San Francisco Planning Department and the Port of San Francisco were contacted and an additional list of projects was obtained. As noted below, these projects have been added to Table 5.1. Please see response to Comment F52 for a discussion of an updated cumulative effects analysis.

Table 5.1 of the DEIR (page 5-12) is hereby amended to include the following additional projects known or anticipated by the San Francisco Planning Department and the Port of San Francisco:

F52 The updated list for the Mission Bay/Potrero/Bayview-Hunters Point area includes a wide variety of projects. Some are very small in size and would clearly have a negligible impact on air quality. Others are larger in size, such as the Bayview-Hunters Point Redevelopment Area and Mission Bay projects, but would generate PM-10 primarily through mobile sources. Mobile-source emissions of PM-10 would be distributed over a wide geographic area, not just in the immediate vicinity or even just in San Francisco. The geographic area of impact would be defined by the locations of the origins and destinations of individual vehicle trips generated by these projects. In other cases, the projects themselves would reduce the number of stationary PM-10 sources by converting industrial land uses into residential or commercial land uses.

However, among the projects listed in Table 5.1 (as supplemented in response to Comment F52), there are six that would have the potential to significantly affect local PM-10 concentrations because they include stationary sources that could potentially generate substantial amounts of direct PM-10. These six projects include: (1) the Construction and Building Materials Supply Center at Piers 90 and 92, which would include a concrete recycling facility and two ready mix batch plants; (2) the RMC Lonestar Pier 90 Lease, which would include a concrete ready-mix facility; (3) Crushcom, which would include a concrete/rock-crushing operation; (4) Tidewater Sand and Gravel Facility, which would extract sand and gravel from the Bay and dry it on site; (5) Bedrock RediMix, which would include a concrete batch mixing facility; and (6) Specialty Crushing, Inc., which would include a concrete crushing facility.

PM-10 emissions generated by these projects would depend upon a number of variables including the exact industrial processes to be used, the size of the equipment and machinery, and the amount of material throughput. Also, PM-10 emissions and corresponding cumulative PM-10 concentrations would be affected by conditions and limitations set forth in air permits issued by BAAQMD. Unlike the projects generating only mobile-source emissions, these projects would include substantial new stationary emissions sources, and as such, these projects would be subject to BAAQMD regulations that will require implementation of Best Available Control Technology (BACT) and may also require offsets if certain trigger levels would be met. BACT, in this context, could include use of fine sprays or filters or other techniques to reduce direct PM-10 emissions.

Since the variables cited above and the specific emissions controls that would be required by BAAQMD are unknown, an estimate of the cumulative PM-10 concentration from these six sources cannot be made at this time. However, given BAAQMD’s regulatory authority and control over the PM-10 emissions sources associated with these projects, it is not clear whether their cumulative effect would be significant. Nonetheless, when further defined, these projects would be subject to separate, project-specific environmental review by the City and County of San Francisco and/or the Port of San Francisco and other agencies with jurisdiction over their operation, at which time the potential for these impacts to occur would be fully evaluated.

The local background concentrations of PM-10 do occasionally exceed the 24-hour state standards and the project would contribute PM-10 to the environment. However, the small additional amount of PM10 contributed by the project should not be considered cumulatively significant even in light of the arguably serious nature of the already existing problem. Furthermore, the state 24-hour PM-10 standard is only one-third of the federal 24-hour PM-10 standard. By adopting the more restrictive standard, California has increased the controls on PM-10, but this strict standard is being met in only one county (Lake County) of the 58 counties in California. In light of the recently reviewed federal 24-hour PM-10 standard (which remains 150 µ g/m³), a background level of 50 µ g/m³ may not be a severe environmental condition.

In any event, the proposed divestiture’s contribution to cumulative PM-10 impacts would not be cumulatively considerable. Recent changes to the CEQA Guidelines support the conclusion that just because the total of the proposed divestiture in combination with other cumulative projects (in addition to the background concentration) would be above the 24-hour state PM-10 standard, 50 µg/m³, does not mean that the project’s contribution to a significant cumulative impact is cumulatively considerable and, thus, significant. Paragraph (a)(4) of Section 15130 of the CEQA Guidelines now states that an EIR may determine that a project’s contribution to a significant cumulative impact is de minimus and, thus, is not significant. A de minimus contribution means that the environmental conditions would essentially be the same whether or not the proposed project is implemented.

Table 4.5-29 shows that PM-10 concentrations would be higher under the 2005 Cumulative Analytical Maximum scenario than the 1999 baseline conditions. However, since the modeled cumulative increase (difference between the two scenarios) in local PM-10 concentrations would essentially be the same with or without the project’s negligible contribution of 0.8 µg/m³, the project’s contribution to any significant cumulative impact would be considered de minimus given that the background concentration is estimated to be 57 µg/m³. Because this project would result in less than a 1 µg/m³ increase on the maximum day (which is even less than the PSD annual average significance limit), the effect of the project is clearly de minimus with respect to PM-10. On this basis, it is determined that the project would not result in a cumulatively considerable impact to local PM-10 concentrations. It is also that the 5.0 µg/m³ significance threshold used in the DEIR for evaluating PM-10 concentration impacts was used in determining the significance of PM-10 impacts in the CEC’s decision on the San Francisco Energy Company’s Cogeneration Project (Docket No. 94-AFC-1). The CEC decision notes that U.S. EPA characterized the 5.0 µg/m³ increment as the "level below which it would not require any impact analysis on the ground that such impact levels are simply insignificant, even ‘in [the] most stringent regulatory context (i.e., the 24-hour average).’"

F53 The likelihood that new owners of the fossil-fueled plants would tend to operate at higher levels than PG&E, and the methods used to evaluate this potential change, are discussed in the DEIR in Chapter 3. Refer to Section 3-5 for discussions of the factors that could produce change as a result of divestiture, including incentives for new owners to operate at higher levels.

The commenter argues that subjective considerations were used to develop the concept of the "Analytical Maximum" scenario that were used in the analysis. However, the Analytical Maximum case was carefully developed in the DEIR to take into account all three possible reasons for future higher operation rates by new owners: the portfolio effect, fuel procurement practices, and the new owner’s ability immediately to participate in the direct access market. As to the portfolio effect, the modeling assumed that the plants were owned by single owners. Regarding direct access, the modeling assumed that the new owners would have the opportunity to participate in that market. The model assumed that low gas prices would simulate extraordinarily beneficial fuel procurement practices.

The Analytical Maximum case was developed to represent a very high, but still plausible, level of hourly operations consistent with each plant’s forced outage rate and maintenance schedule. On an hour-by-hour basis, the Analytical Maximum would not violate the reliability constraints (e.g., scheduled outages for maintenance), supply/demand constraints, or transmission constraints that could never be intentionally ignored in the real world. In balancing hourly loads and resources it was assumed that, regardless of new ownership, generation from the divested plants would not be able to displace must-run, must-take hydro, and very low-priced coal-fired generation. Thus, the Analytical Maximum scenario was employed to determine a realistic maximum level of generation for a new owner whose operations rate would always be constrained by demand for electricity.

The most straightforward way to implement each Analytical Maximum forecast presented in the DEIR was to lower the hypothetical fuel cost so much that operation of the fossil-fueled plants being divested would essentially be preferred over all other fossil-fueled plants not being divested. The lower gas prices reflect not only potential access to discounted gas contracts, but also lower transaction and cycling costs due to greater potential for direct access sales and a lack of a generation portfolio to support cycling operations. (Please see the response to Comment E2 for additional information.) These assumptions produced an Analytical Maximum level of operations that was reduced from each plant’s physical maximum only to a degree necessary to reflect inviolate, real-world impediments.

In any event, in the case of the Potrero Power Plant, the Analytical Maximum and the physical maximum cases would be very similar. In neither case can the three combustion turbines (CTs) run more than 10 percent of the time due to BAAQMD rules. It is implausible that the CTs would operate even as much as 10 percent of the time because they run on diesel, must continue to contribute to the demands of the San Francisco Operating Criteria, and are dispatched as Must Run Category C units by the ISO. The physical maximum capacity factor for the Potrero 3 boiler unit in 1999 would be 88 percent when forced and planned outages and deratings are taken into account. Thus, the physical maximum possible capacity factor for the entire Potrero plant (including the CTs) would be 54.6 percent, only about 10 percent higher than the 1999 Analytical Maximum case. In this instance, because the Potrero plant operating at its physical maximum would produce such a small amount of additional generation when viewed in the context of the State of California as a whole, the Analytical Maximum is not very much less than the physical maximum and certainly captures the maximum potential environmental impacts of divestiture.

F54 Please see the response to Comment F53. The Analytical Maximum capacity factors used in the DEIR are less than the corresponding physical maximum values. The physical maximum, however, is not an appropriate measure to use in analyzing project effects because of its real-world implausibility. The likelihood of a plant running at its physical maximum is nil given the system constraints, the limitations on electricity demand (e.g., low demand in the middle of the night limits plant potential output), and the economic considerations faced by any owner.

In addition, calculating the physical maximum might be done easily, but the results could not easily be incorporated into the SERASYMÔ model to assess hypothetical cumulative impacts. The analytical maximum takes into account system constraints and therefore is realistic; the physical maximum does not and is not.

F55 The commenter notes that we live in a changing world and that "very little with respect to the PX and ISO stays constant these days." It is agreed that the operations of the PX/ISO may change in the future. However, no plausible potential changes of which the EIR preparers are aware would do away with requirements for system reliability or with the objective of procuring minimum cost generation. The case evaluated in the Analytical Maximum scenario in the DEIR considered that plant operations would increase to an extent that would fully capture any credible foreseeable changes in system operations. Please see the responses to Comments F53 and F54.

F56 The modest transmission modifications that PG&E is now completing with respect to imports into the City are reflected in the 1999 Baseline and the 1999 Analytical Maximum cases. These are described in the DEIR in Chapter 3 and summarized on pages S-7 and S-8.

More significant transmission projects are reflected in the 2005 Cumulative Impacts case entitled "Variant 1." This variant is described in the DEIR on page 3-13, bottom paragraph. It is also explained in Table 5.2 in the DEIR, starting on page 5-17 (refer to note "e"). The results of the 2005 Cumulative Impacts case, including all variants, are presented in the DEIR in Table 5.2.

F57 The commenter correctly acknowledges that there is uncertainty as to where and when new power plants will be added to the power grid in the western region. Chapter 5, Cumulative Impacts, of the DEIR, addresses the potential for environmental impacts to occur from the development of new power plants in combination with the divested PG&E power plants in 2005. Specifically, Section 5.2.2 (pages 5-3 to 5-7 of the DEIR) discusses reasonably foreseeable future power plant development throughout California (including new generation to replace the Hunters Point Power Plant in San Francisco). In recognizing the uncertainty surrounding the development of these plants, the DEIR states on page 5-5 that "it is unknown at this time which of these power plants, if any, will eventually be constructed." To avoid underestimating the localized effects of the proposed project together with cumulative projects, most of the power plants that are discussed in Section 5.2.2 as proposed new plants were excluded from the detailed cumulative modeling and analysis on pages 5-16 to 5-42 of the DEIR. First of all, the development of these plants was considered to be too speculative to include them in the analysis. Secondly, as described on pages 5-2 and 5-7 of the DEIR, development of new power plants would increase the overall generation capacity in California, thereby decreasing the likelihood that the plants proposed for divestiture would operate at higher levels in the future. As described on page 5-2 of the DEIR, the exception to this premise is that all future projects deemed necessary to support localized demand for electricity by 2005 are carried forward into the analysis. The discussion under Section 5.3, Potential Cumulative Impacts, on page 5-16 of the DEIR, summarizes those power plants that are assumed to be developed under the various cumulative scenarios.

As mentioned above, the DEIR explains that an increase in overall generating capacity resulting from the development of new power plants would decrease the tendency of new owners of the divested power plants to increase operations at such plants. This suggests that an increase in the number of new power plants being developed would result in a decrease in generation at the divested power plants. Conversely, the development of fewer new power plants would increase the tendency for the new owners of the divested plants to maximize the operation of those plants. This concept is illustrated in Table 5.2 (pages 5-17 and 5-18 of the DEIR), which shows annual plant capacity factor estimates for each of the four plants being divested under various cumulative scenarios. Of the three cumulative scenarios shown in Table 5.2, the Variant 2 scenario represents the scenario with the greatest overall generating capacity in terms of number of plants and the size of plants. When compared to the basic 2005 Cumulative Analytical Maximum, the annual plant capacity factor at each of the divested power plants decreases. If the excluded power plants described in Section 5.2.2 were included in the modeling, it is anticipated that the annual plant capacity factor of the divested plants would be even lower than is shown in Table 5.2.

Following publication of the DEIR, subsequent SERASYM™ modeling was completed for San Diego Gas and Electric Company’s (SDG&E) proposed divestiture of its electric generating facilities, a refueling facility and long-term power supply contracts. The results of these modeling efforts are presented in SDG&E’s Mitigated Negative Declaration and Initial Study California Public Utilities Commission, San Diego Gas and Electric Company’s Application No. 97-12-039, Proposal for Divestiture, published on October 13, 1998. The analysis determined that because of increased transmission capability into the San Diego region, not known at the time of DEIR publication, the proposed Otay Mesa Power Plant described in Section 5.2 of the DEIR would not be needed to meet projected demands. The modeling completed for SDG&E’s proposed divestiture showed that the removal of the Otay Mesa Power Plant, in addition to other system-wide upgrades, resulted in no increase in capacity factors at the PG&E plants being divested from the capacity factors presented in the DEIR. In summary, the conclusions of these more recent modeling efforts would not affect the conclusions in the DEIR.

F58 Section 3.4 of the DEIR (pages 3-4 and 3-5) (not of Attachment C) must be read in context with Section 3.5 of the DEIR. Section 3.4 does not list these factors "as too speculative to consider at this time." Section 3.4 lists and discusses the types of factors that could produce environmental change, e.g., changes in the amount of energy generated at a particular plant or in the number of employees at such plant. Section 3.5 then describes the DEIR’s assumptions concerning the changes that divestiture would reasonably foreseeably effect, e.g., new owners having a tendency to generate more electricity than PG&E. The Analytical Maximum capacity factors go beyond capturing these reasonably foreseeable changes so as to conservatively depict the potential impact of the project.

F59 The analysis to the extent feasible accounts for the possible range in changes from restructuring. Attachment C discusses the rationale for how the effects of restructuring were separated from those of divestiture, and how the incentives of new owners might differ from those of PG&E. Note that the sentence quoted by the commenter relates to restructuring, and not to divestiture.

F60 The commenter suggests that the use of the physical maximum in the Final EIR would capture all of the effects of changes in operating mode and fuel costs, rendering use of the Analytical Maximum unnecessary. Please see the responses to Comments F53 and F54 regarding the Analytical Maximum and physical maximum concepts.

The change in fuel prices that was used in the Analytical Maximum case was misunderstood by the commenter. The fuel price used in the analysis was 25 percent cheaper than the cheapest natural gas projected to be available in California in each month considered. In each month of 1999 and 2005 where the Analytical Maximum estimates were made, the cheapest gas was projected to be available to the Cool Water plant in the Mojave desert. This projection is due to the near complete absence of inter- and intra-state gas transmission charges. Since gas service to the plants projected for divestiture incurs much larger gas transportation charges, the forecasted monthly price of natural gas fuel for the PG&E plants proposed for divestiture are significantly higher in the basecase. Thus, the reduction in fuel price employed in the Analytical Maximum cases was significantly more than 25 percent below (depending upon the month and year) the fuel price assumed in the baseline case if PG&E were to retain the plants.

In addition, the operational studies using the Analytical Maximum scenario have already been completed, making the suggested implementation of the physical maximum an unnecessary exercise that would not affect the conclusions of the DEIR.

F61 Please see the responses to Comments F53 and F54. The commenter provides no reasonable rationale for why use of the hypothetical physical maximum could more accurately account for future uncertainties in plant operations. On the other hand, the DEIR analysts, CPUC staff, and commenters have not identified any scenario that would allow future generation levels to exceed the Analytical Maximum scenario that was evaluated in the DEIR. The Analytical Maximum approach yields a realistic upper bound on possible generation without considering the highly implausible physical maximum levels of generation.

F62 The approaches used in the DEIR to address the health impacts from exposure to increases in PM-10 and PM-2.5 emissions go beyond those typically carried out under CEQA. The levels chosen were not based on administrative rules, but were based on levels that have shown to cause statistically significant health effects. EIRs usually compare the estimated concentration increases with the ambient air standards to test for significance. This was done in the EIR when comparing increases from divestiture with baseline emissions to determine if the project would contribute to a violation of a standard. In the case of particulate matter, background measurements indicated that the state PM-10 standard has already been exceeded on occasion. Therefore, the significance threshold identified in significance criterion #1 (see DEIR page 4.5-50) was used, which is based on the BAAQMD definition for a measurable contribution to a standard violation. For criterion #1, the significance threshold is 5 micrograms per cubic meter for a 24-hour average increment and 1 microgram per cubic meter for an annual average increment.

To be conservative, the DEIR also compares contributions from the entire plant emissions (existing emissions plus emissions from divestiture) with PM-10 increases that are considered to cause significant health effects based on relative risk coefficients for particulate matter exposure. Although the DEIR did not use a rigid statistical approach, the preparers relied on the information on relative risks that were reported by EPA in the Particulate Matter Criteria Document (USEPA, 1996a) and in the EPA-OAQPS Staff Paper (USEPA, 1996b) to determine if the contributions from the plants would result in acceptable levels. The PM-10 concentrations reported in the DEIR are for worst-case receptors and are not indicative of typical exposure levels in the region. Average levels around the plants, which are actually more representative of public exposure, are about one-tenth of these maximum levels. This is principally because the public is usually not located within the prevailing wind direction from the plants. The DEIR does not ignore the breadth of human health effects related to particulate matter exposure. It does not state that there is a threshold below which there are no impacts, nor does it reject the possibility of a linear dose-response effect extrapolated to zero, even though the studies cited in the literature do not conclusively reject the potential for a threshold exposure level (see USEPA, 1996a, Vol. III, pp. 12-22 through 12-24). Instead, the DEIR relies on the information pertaining to relative risk coefficients reported in the literature to establish exposure levels that may cause significant health effects. The ranges showing significant effects were increases of 20 to 50 µg/m³. There is even greater uncertainty when increases range from 10 to 20 micrograms per cubic meter. This uncertainty is described further in response to Comment F74.

References:

U.S. Environmental Protection Agency, Air Quality Criteria for Particulate Matter, EPA/600/P-95/001cF, April 1996a.

U.S. Environmental Protection Agency, Review of the National Ambient Air Quality Standards for Particulate Matter, Policy Assessment of Scientific and Technical Information, EPA-452/R-96-013, July 1996b.

F63 The impact analysis used the ambient air standards which are health-based. Therefore, it was not necessary to carry out separate risk assessments for the criteria pollutants. For criteria pollutants, such as PM-10, that already exceed the state ambient air standards, strict limitations on concentration increases which are related to measurable thresholds as identified in the BAAQMD PSD regulation were used to determine whether the project would cause health effects. Since the ambient air standards for the other criteria pollutants (NO₂,SO₂, and CO), which are health-based, were not exceeded as a result of the project, the health effects were considered less than significant.

F64 The DEIR focused on the worst-case potential impacts from plant emissions, which involved local receptors. The modeled impacts from the plant emissions on receptors farther away in the region were found to be considerably lower than the local impacts and thus do not require further analysis.

F65 The DEIR focused on the worst-case off-site receptors at residences and at locations that included sensitive receptors, such as schools. Since the modeled concentrations at these receptors were found to be less than significant, levels at sensitive receptors farther from the plants would be even lower. Therefore, further analysis for all exposed populations was not carried out because the levels are less than significant. Please also see response to Comment F67 regarding identification of exposed populations.

F66 The approaches used to assess the health effects from the project considered the most sensitive health outcomes. For toxic substances that are not criteria pollutants, the EIR used the methods consistent with AB 2588. For criteria pollutants, the ambient air standards were used to assess impacts, since they are health-based standards. For criteria pollutants that occasionally exceed an ambient air standard, such as particulate matter, more restrictive concentration increases were used, based on measurable concentration thresholds and relative risk coefficients. However, studies in the literature that are cited in the EIR show large variations and uncertainties in relative risks for various endpoints, especially for moderate increases in particulate matter. Since the relative risks for many of these endpoints overlap, the risks for all endpoints were grouped together, and the general term "respiratory-related health effects" was considered in the DEIR. Various health effect endpoints from exposure to particulate matter were described on pages 4.5-7, 4.5-31, and 4.5-32 of the DEIR.

F67 Based on discussions with staff at the BAAQMD in determining the proper CEQA analyses, it was agreed that population health burden should not be included in the analysis, because of uncertainties in the population demographics and greater uncertainties in estimating actual exposure by these populations. Instead, it was agreed that the EIR should focus on the maximum incremental risk at the worst-case receptor and to determine if the estimated increases are significant.

F68 Studies cited in the literature indicate that health impacts from acute and chronic exposure to particulate matter are closely related. The EPA Criteria Document states that long-term exposure often reflects the net sum of acute events that took place in a year (USEPA, 1996, V III, P 12-138 and 12-139). Thus, long-term (chronic) health effects associated with exposure to particulate matter are likely to reflect some combination of acute and chronic effects.

The paragraph in the DEIR referred to in the comment describes some of the effects of exposure to particulate matter. It was not intended to provide an exhaustive description of all of the health effects, many of which are very similar. The literature cited in the paragraph in the DEIR are examples of the numerous studies that have been carried out. Many of these studies relied on the same data sets with slightly different interpretations. The EPA Criteria Document for particulate matter and the EPA Staff Assessment report are good compendia of these studies. The last paragraph on page 4.5-7 is hereby amended as follows to include these compendia:

Several studies that EPA relied on for their staff report have shown an association between exposure to particulate matter, both PM-10 and PM-2.5, and respiratory ailments or cardiovascular disease (Pope et al., 1992; Thurston et al., 1992; Burnett et al., 1995). Other studies have related particulate matter to increases in asthma attacks (Whittemore and Korn, 1980; Pope et al., 1991). In general, these studies have shown that short-term and long-term exposure to particulate matter can cause acute and chronic health effects. The EPA Criteria Document and the EPA Staff Report on Particulate Matter (USEPA, 1996a, and 1996b) are compendia of the many studies related to health effects from particulate matter exposure. Fine particulate matter (PM-2.5), which can penetrate deep into the lungs, causes more serious respiratory ailments. These studies, along with information provided by EPA in the 1996 staff report, were used as the basis for evaluating the impacts of PG&E emissions of PM-10 and PM-2.5, on public health.

F69 The following language is hereby added to the end of the last sentence of the first full paragraph on page 4.5-12 of the DEIR:

…(pages 4.5-26 through 4.5-32).

The commenter also requests that Appendix G be cross referenced for risk assessment methodology information. Upon inspection, there is no risk assessment or methodology information contained within Appendix G and, thus, no further response is required.

F70 As related to the wind rose (Figure 4.5-2 of the DEIR) for the Potrero Power Plant, the nearest residences and population centers are located to the west and southwest (e.g., Potrero Hill) and south (e.g., Bayview/Hunters Point) of the plant sites. This can be seen to some extent on Figure 2.2 and, for the immediate plant vicinity, Figure 4.1-4 provides local zoning designations surrounding the site. Per the predominate winds shown on Figure 4.5-2 (southwest, west-southwest, west and west-northwest), the areas downwind of the site are all off-shore in San Francisco Bay. Only a few percent of the days annually are winds observed that would cause the nearby population centers to be down wind of the power plant (i.e., winds from the east). Please see the response to Comment 4-2, for which a special wind rose was developed further illustrating this point. The commenter suggests that the approximate population sizes of these areas be stated. Population data is presented in Section 4.2.2 of the DEIR on the local population size for the Potrero area.

F71 The sentence was intended to give a general description of some of the potential effects of exposure to particulate matter and was not intended to include all possible health effects. However, it does identify both respiratory and cardiac related effects as possible outcomes. A more comprehensive description is given earlier in the document (DEIR page 4.5-7, third through fifth paragraphs) in which both acute and chronic respiratory effects and cardiovascular effects are identified. The sentence in the DEIR that is referred to by the commenter identifies mortality as one of the outcomes from exposure to particulate matter, and was not intended to downplay this potential effect.

F72 The sentence referred to (second full paragraph on page 4.5-31 of the DEIR) does not state that only areas with high short-term levels of particulate would result in health effects. It does cite several prominent studies that show health effects in cities during air pollution episodes. In several of these studies, short-term (24-hour average) levels exceeded 300 micrograms per cubic meter. The statement in the second paragraph that refers to typical annual average background levels ranging from 18 to 58 micrograms per cubic meter in these cities is not inconsistent with the high particulate matter levels that were observed during episodes. These differences between annual average concentrations and high short-term levels are typical for many urban areas.

The second sentence of the second full paragraph on page 4.5-31 of the DEIR is amended as follows:

Most Many of these studies have shown relationships between particulate matter exposure and cardio-pulmonary effects during air pollution episodes in major metropolitan areas, where daily ambient air concentrations exceeded 300 micrograms per cubic meter µg/m³.

F73 Page 4.5-31 of the DEIR (third full paragraph) is hereby amended as follows:

"A draft study report released by the Bayview Hunters Point Health and Environmental Assessment Task Force (Aragon and Grumbach, 1997) reported that 1992 hospitalization rates for asthma, hypertension, diabetes and congestive heart failure are were higher in this area Bayview Hunters Point than any other part of San Francisco. However, the draft study does did not identify the cause(s) of the observed increased respiratory problems, and does did not consider individual pollutant exposure. To better understand the causes of the increased incidences hospitalization rates, a detailed study would have to be carried out..."

F74 By citing the relative risks that were reported for a 20-25 microgram per cubic meter increase in PM-2.5 concentration, the DEIR does not reject the possibility of a linear relationship between exposure and health effect, although the EPA Criteria Document on Particulate Matter (USEPA, 1996a) indicates that the interpretation of specific concentration-response relationships is the most problematic issue when determining if the response is linear. This is due to the absence of clear evidence on the mechanisms for various health effects at lower concentration exposure levels (USEPA, 1996a, p. 13-87). Although most models assume a linear, no-threshold underlying relationship that potentially extend to zero concentrations, the existing data do not rule out the possible existence of an underlying non-linear, threshold relationship. The studies reported in the EPA Criteria Document indicate that there is considerable variability in the relative risks with estimates varying by a factor of 5 when concentration increases of 10 micrograms per cubic meter are considered. Information in the Criteria Document showed less variability in relative risks for a 20–25 microgram per cubic meter increase. In addition, Volume III of the Criteria Document (pages 10A-12 through 10A-17) states that total respiratory tract deposition of particulate matter reaches a minimum in the size range between 0.2 microns and 1.0 micron. The information on deposition in the Criteria Document is confirmed by another study (Raabe, 1984). This is important because it is the size range expected for a considerable portion of particulate matter emissions from gas-fired steam boilers (U.S. EPA, 1998). In effect, of all particle sizes, these particles are the least likely to be trapped in the lungs and the most likely to be expelled from the lungs during breathing. This information adds to the uncertainty of health effects from exposure to emissions from gas-fired boilers at the PG&E units, although this factor would reduce concern from particles of this size.

In choosing levels that could be used to judge the health effects from the project emissions, the EIR followed the methods used by EPA when establishing new fine particulate matter standards. In its Policy Assessment of Scientific and Technical Information for Particulate Matter (USEPA, 1996b), the Office of Air Quality Planning and Standards states on page VII-1:

A final decision (on PM-2.5 standards) must draw upon scientific information about health effects and risks, as well as judgments about how to deal with the range of uncertainties that are inherent in the scientific evidence and analyses. The Staff’s (EPA) approach to informing these judgments is based on a recognition that the available health effects evidence generally reflects a continuum consisting of levels at which scientists generally agree that health effects are likely through lower levels at which the likelihood and magnitude of the response becomes increasingly uncertain. This approach is consistent with the requirements of the NAAQS provisions of the Clean Air Act and with how EPA and the courts have historically interpreted the Act. These provisions do not require the Administrator to establish NAAQS at a zero-risk level but rather at a level that avoids unacceptable risks and, thus, protects public health with an adequate margin of safety.

With regard to evaluating the significance of changes in plant operations due to divestiture (direct project impacts as opposed to total plant operations), the more restrictive significance criterion #1 was used (as defined on page 4.5-50 of the DEIR), in which 24-hour PM-10 concentration increases exceeding 5 micrograms per cubic meter was considered to be significant.

CEQA analysis depends upon determining what is a significant environmental impact and does not assume that any increase is significant, even if the increase is linear or could be linear. With this in mind this EIR does not use a standard that a one particle increase in PM-10 would be a significant impact. Rather, the EIR uses significance standards based on concentrations that have shown more certain health effects.

Reference:

Raabe, O., Deposition and Clearance of Inhaled Particles, chapter in Occupational Lung Disease, Gee, J, K. Morgan, and S. Brooks, Editors, Raven Press, 1984.

F75 The PM-10 significance criteria mentioned on numbered item 1 on page 4.5-50 are taken from BAAQMD Regulation 2, Rule 2 as mentioned in the second sentence of that DEIR paragraph. Thus, there is no need to modify this text.

F76 Please see response to Comment F74 for the first part of the comment regarding how 24-hour average and annual average significance criteria were selected. The significance levels identified in the comment were used to evaluate the consequences of total plant operations (existing plus project impacts). The cumulative effect is included, since the EPA information on relative risks coefficients was based on concentration increases over typical urban background levels, which included other sources.

The increases for PM-10 are not less than those for PM-2.5. They are the same, because it is assumed that all of the emissions from the plant are less than 2.5 microns. The incremental increases mentioned in the comment regarding criterion #1 are for both PM-10 and PM-2.5. The increases referred to in criterion #1 are related increases from divestiture as compared with the baseline environmental conditions. The concentration increases identified in criterion #1 are more restrictive than criterion #4, because #1 deals with emissions changes from the divestiture project, whereas #4 includes total plant emissions (baseline plus divestiture. The response to Comment F74 provides an explanation on the rationale for choosing the numerical targets, and it cites the documents that were relied upon.

The comment regarding the number of days exceeding 20 micrograms per cubic meter refers to Tables 4.5-30 and 4.5-33 in the DEIR. These tables show the number of days that the contributions from the plants (baseline plus divestiture) are expected to exceed certain intervals. The frequencies on the tables identify the number of days in a year that specified threshold levels would be exceeded at the worst-case receptor if a year of daily operations were input to the model. The year of daily operations was derived from SERASYM™ model runs based on energy demand. Tables 4.5-30 and 4.5-33 show that there are no days in which the 20 microgram per cubic meter threshold would be exceeded.

F77 The change in designation for the national ozone standard does not affect significance criterion #5 (on page 4.5-51 of the DEIR) since that criterion was developed to assess consistency of the project with the ’97 Clean Air Plan, which was prepared to address the nonattainment status of the Bay Area with respect to the more stringent state ozone standard, not the national ozone standard.

F78 The PM-2.5 values shown in Table 4.5-29 represent the specific time period and the value added to the representative background value. For example, 1999 Baseline PM-2.5 values listed in Table 4.5-29 as 1.2/1.2 indicate that, for the first value of 1.2, the expected 1999 Baseline value for Potrero would be 1.2 µg/m3. The second 1.2 indicates that the Potrero plant contribution, when added to the background value of "ND" (i.e., no data), is also 1.2 µg/m3. Any confusion stems from the fact that there are no values currently available for PM-2.5 backgrounds, and there will be none available for several years until the BAAQMD completes its initial PM-2.5 monitoring program. To eliminate any confusion, Table 4.5-29 (and similar values for Tables 4.5-31 and Table 4.5-32) is hereby amended to read as follows:

For particulate matter (PM-2.5), 24-hour values for the following columns are all changed to read:

F79 Please see responses to Comments F30 and F31.