State of California AIR RESOURCES BOARD State Office Building Room 1194 455 Golden Gate Avenue San Francisco, CA September 20, 1976 10:00 a.m. AGENDA 76-17-1 Approval of Minutes of August 10 Board Meeting. 76-17-2 Emergency Plan - Consideration of Traffic Reduction Strategies During Oxidant Emergency Episodes and Criteria for Combination Oxidant - Sulfur Dioxide Emergency Episodes. 76-17-3 Staff Report on San Diego Gas and Electric Company Encina No. 5 Power Plant. 76-17-4 Other Business - (a) Executive Session - Personnel and Litigation (b) Research Proposals ITEM NO.: 76-17-2 Emergency Plan (a) Consideration of Traffic Reduction Strategies During Oxidant Emergency Episodes, and (b) Criteria for Combination Oxidant - Sulfur Dioxide Emergency Episodes. RECOMMENDATION This is an informational report requested by the Board. No specific action is required. SUMMARY (a) The University of San Diego statistical study shows that, at certain inland locations where high oxidant concentrations occur frequently in the summer months, the concentrations observed on weekends are statistically significantly lower than concentrations observed on weekdays, suggesting that a strategy of creating weekend traffic patterns when oxidant emergency conditions are forecast would be effective in reducing or preventing Stage II and III conditions. Such strategy would not be equally effective at locations near the coast and might be counter productive during the winter. (b) The Department of Health has recommended that a 0.1 ppm cutoff be applied to the SO2 concentrations as well as the oxidant concentrations in the criteria for combined SO2-oxidant emergencies. Analysis of 1975 air quality data for the South Coast Air Basin suggests that the proposed criteria would result in a few Stage II episodes which would not have occurred under the oxidant criteria alone. It would appear that these episodes would result from adding relatively low concentrations of SO2 to near episode concentrations of oxidant, rather than vise versa. The Board asked the staff to ask the oil companies and power companies in the South Coast Air Basin to outline their plans to meet the Emergency Plan requirements to reduce SO2 emissions. The staff report summarizes the comments of the companies that have responded. ITEM NO.: 76-17-3 San Diego Gas & Electric Company Encina 5 Power Plant. SUMMARY San Diego Gas and Electric Company has started construction of a fifth generating unit at their Encina power plant and plans to erect a 400-foot stack to disperse the pollutants from all five generating units so as to avoid violating the state 24-hour SO2 and one-hour NOx air quality standards at the site of the power plant. RECOMMENDATION The staff believes that adequate data is not presently available to accurately project the total impact on basin wide air quality from the use of tall stack dispersion methods such as the 400-foot stack being constructed at Encina 5. The staff therefore recommends that it conduct further studies to determine the following: (1) Whether the studies conducted by Stanford Research Institute and Bechtel Power Corporation accurately reflect the total volume and composition of pollutants which would be emitted from the 400-foot stack at Encina 5, particularly in light of recent developments in the availability and cost of low sulfur fuel oil. (2) Whether the studies conducted by the San Diego Air Pollution Control District accurately reflect the total basin wide impact of the emissions from the 400-foot stack at Encina 5 on ambient air quality in the San Diego Air Basin. (3) Whether the anticipated emissions from the 400-foot stack at Encina 5 are likely to interfere with the attainment and maintenance of ambient air quality standards in the San Diego Air Basin or other basins. (4) Whether existing standards for measurement of SO2 and NOx emissions accurately document the impact of such emissions on basinwide ambient air quality. (5) Whether regulations are necessary to require the use of best available control technology to control the volume of emissions from tall stacks in order to prevent such emissions from interfering with the attainment and maintenance of ambient air quality standards.