EXHIBIT 4-2_55A_BRISTOL WIDENING TECHNICAL STUDIES

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I J 3.2 Air Quality Impact Analysis f Two types of air pollutant sources must be considered with re- .! spect to the proposed project: stationary sources and mobile sources. Stationary source considerations include emissions on- site from construction activities as well as emissions at the power plant associated with the electrical requirements of the project. Mobile source considerations include exhaust emissions resulting from short -term construction activities and long -term traffic changes associated with the project. Short- -Terre Impacts Short -term impacts on air quality will occur during the construc- tion activities required to implement the proposed project. These temporary impacts will include: 1) particulate (fugitive dust) emissions from construction activities on -site; 2) exhaust emissions from the construction equip- - meat used on -site as well as the vehicles used to transport the equipment to and from the site; and 3) exhaust emissions from the motor vehicles of the construction crew. On a short -term basis, large dust particles (30 -100 microns in diameter) that settle to earth within a few hundred feet of the construction area could create a temporary localized nuisance problem. Additionally, fine - grained particles (less than 30 microns in size) may be emitted and dispersed over greater dis- tances, occasionally annoying adjacent receptors especially dur- ing Santa Ana wind conditions. An average particulate emission factor for heavy construction activities of 1.2 tons of dust per month of activity per acre disturbed has been cited by the EPA in AP -42. Fugitive dust generation can be reduced by half through dust suppression tech- niques such as regular watering during construction (particularly on unpaved areas used by construction vehicles). Diesel construction equipment constitutes approximately 90 per- cent of the heavy construction machinery in use today. It emits on the average about one -half pound of NOx (and smaller amounts of CO and THC) for each gallon of fuel burned (EPA, AP -42). Con - struction equipment emission rates on very active days may total several hundred pounds of contaminants per hour. Construction of the proposed project is expected to begin in 1989, although no start -up date has been firmly established. It has been estimated that completion of the project could require an estimated 24 construction vehicles over a 6 month period, with construction activities occurring continuously. 3 -6