ARCHIVED REPORTS LEC APPLICATION FOR CERTIFICATION

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5.1 AIR QUALITY 5.1.1.3.9 Airborne Lead The majority of lead in the air results from the combustion of fuels that contain lead. Until 30 years ago,motor gasolines contained relatively large amounts of lead compounds used as octane-rating improvers,with the result that ambient lead levels were relatively high. Beginning with the 1975 model year,however,manufacturers began to equip new automobiles with exhaust catalysts,which are poisoned by the exhaust products of leaded gasoline. Thus,unleaded gasoline became the required fuel for an increasing fraction of new vehicles, and the phase out of leaded gasoline began. As a result, ambient lead levels decreased dramatically, and for several years California air basins,including the San Joaquin Valley Air Basin,have been in attainment of state and federal airborne lead standards for air quality planning purposes. Table 5.1-10 lists the state air quality standard for airborne lead and the levels recorded in the Stockton-Hazelton station between 1998 and 2003.Table 5.1-10 indicates that airborne lead levels have been well below the ambient air quality standard of 1.5 µg/m3 for the period 1998 through 2003. TABLE 5.1-10 Airborne Lead at Stockton-Hazelton, Stockton, 1998-2003(µg/m3) 1998 1999 2000 2001 2002 2003 Highest Daily Average 0.02 0.02 0.03 0.02 0.02 0.02 Number of Day Exceeding Federal Standard (1.5 Ng/m3) 0 0 0 0 0 0 Source: AIRData, EPA 5.1.2 Project Description 5.1.2.1 Current Facility The equipment at the existing NCPA STIG plant consists of one 49 MW GE LM-5000 natural gas-fired, steam-injected (STIG) combustion gas turbine and one 240 HP Cummins diesel fire pump engine. There is also a small cooling tower at the facility,which is exempt from permitting under the SJVAPCD rules because its circulation rate is less than 10,000 gallons per minute (Rule 2020,Section 6.2). The only change to be made to the existing facility is the relocation of the exempt cooling tower. 5.1.2.2 Proposed Facility The proposed combined-cycle unit will consist of a General Electric PG7241FA combustion turbine, a heat recovery steam generator with duct firing, and a 95 MW (nominal) condensing steam turbine,for a total nominal plant output of 255 MW. The CTG will use "Rapid Response" technology. The Rapid Response package,which includes a modified HRSG design and an auxiliary boiler,is designed to allow earlier startup of the steam turbine by decoupling the gas turbine from the HRSG,thereby reducing startup emissions. The project will also include a cooling tower. The combustion turbine, duct burners and auxiliary boiler will be fueled exclusively with natural gas. The combustion turbine will be equipped with an inlet air evaporative cooling system to maintain turbine output across the full range of ambient temperatures. Based on operation at an ambient temperature of 61.2°F,with evaporative cooling of the CTG inlet air to 55.8°F and without duct firing,the facility will have a heat rate of approximately 5.1-20 SAC/371322/082410013(LEC_5.1_AIR_QUALITY.DOC)