75B - PH - AMEND DEVELOPMENT AGMT 2005-02

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MacArthur Project Modification - Santa Ana - Air Quality Assessment KPC Environmental, Inc. 5.0 Air Quality Impact Analysis Air quality impacts/emissions associated with a project can be placed into two categories, temporary (short-term) or long-term emissions. Temporary (short-term) emissions are generally associated with the demolition, grading, and construction activities of the project while long-term emissions are associated with the day-to-day operation, use, and area emissions from such activities as vehicle use, consumer product use, and energy generation/consumption. Short-term emissions will be covered under section 5.1 Construction Emissions while long-term emissions will be covered under section 5.2 Area and Operational Emissions. The emissions estimates for the proposed projects present the "worst-case" scenario with limited mitigation included in the modeling and PM-10 (fugitive dust) from grading activities calculated at the worst-case level of 20 lbs. /day instead of the average 10 lbs. /day. The construction schedule is based on 260-working days for all construction related activities (excavation/grading, trenching, construction, and architectural coating). The emissions calculations assume that the majority of the equipment is operating 5-days per week for 6 to 8-hours each day. It is highly unlikely that the majority of the equipment on-site will be operated at this projected schedule producing the calculated emissions each day. Modeling of emissions from the proposed project is based on the square footage calculations and information presented on the project site plan with construction equipment estimates and scheduling based on URBEMIS Defaults or modified based on familiarity of similar projects. The type and number of equipment and length of schedule chosen for each phase has been selected to present a "worst-case" scenario for construction related emissions. The area and operations emissions were generated with no mitigation measures to present the "worst-case" scenario for the site's impact on the local area. Mitigation measures that shall be employed along with additional mitigation measures that could be employed to further reduce emissions of the construction and operation of the proposed project will be discussed in section 6.2 of this assessment. 5.1 Construction Emissions: Construction emissions can be distinguished as either onsite or offsite. Onsite emissions generated during construction principally consist of exhaust emissions (CO, ROGNOC, NOx, SOX, PM10, CO2 and PM2.5) from construction equipment, fugitive dust (PM10 and PM2,5) from grading and excavation, and ROG emissions from asphalt paving and architectural painting. Offsite emissions during construction typically consist of exhaust emissions from truck traffic and worker commute trips; road dust associated with traffic to and from the construction site; and fugitive dust (PM1o and PM2_5) from trucks hauling materials, construction debris, or excavated soils from the site. 02/02/11 12 75B-120