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6.B. - Page 13 of 28 Appendix 1: AQ/HRA SOW not limited to, California Air Resources Board (ARB) EMission FACtors (EMFAC) model (EMFAC2017), ARB Off -Road Equipment Emission Factor Databases, and US Environmental Protection Agency (EPA) AP -42 Compilation of Air Pollutant Emission Factors. Where project -specific motor vehicle information is not available (e.g., employee or resident commute trips), typical fleet mix data will be used. The analysis will assume one emergency generator for each parcel containing office space. Air quality default modeling assumptions will be used for any construction and operational data not provided by the project applicant. The health risk assessment (HRA) will evaluate known construction and operational TAC emissions on existing nearby off-site and future on-site sensitive receptors using methods recommended by BAAQMD. BAAQMD recommends that any proposed project that includes the siting of a new source or sensitive receptor assess impacts within 1,000 feet, taking into account both individual and nearby cumulative sources. The BAAQMD Recommended Methods for Screening and Modeling Local Risks and Hazards provides additional guidance on methodology for the TAC analysis. The HRA will satisfy the requirements of the Downtown Precise Plan EIR. The American Meteorological Society/EPA Regulatory Model (AERMOD) dispersion model (Version 18081) will be used to estimate pollutant concentrations at specific distances from emission sources. These include the adjacent EI Camino Real corridor and nearby Caltrain corridor. The modeled concentrations will then be used to estimate the long-term effects of TACs on nearby off-site and future on-site sensitive receptor locations. Dispersion modeling for annual exposure to particulate matter less than 2.5 microns (PM2.5) will be conducted using AERMOD with PM2.5 emission rates from exhaust generated by CalEEMod. HARP2 software will be used to assist in the development of emissions inventories, dispersion modeling, and risk assessment. Maximum hourly and period -average files generated by AERMOD will be input to HARP2 (Version 18159) with corresponding TAC emission rates for each phase of construction to calculate project concentration contributions at off-site sensitive receptors. HARP2 will be used solely to estimate cancer risk, chronic non -cancer risk, and acute hazard index (HI) consistent with the exposure factors and guidance from BAAQMD and the Office of Environmental Health Hazard Assessment (OEHHA). The operational HRA may be performed in one of two ways: 1) A screening approach using existing HRA output from BAAQMD screening tools and/or recent HRA documents for vehicle emissions on EI Camino Real, Caltrain diesel emissions, nearby existing source emissions, and the diesel generator screening tool for any new generators to determine if the PM2.5, cumulative cancer risk, chronic non -cancer risk and acute HI are less than the cumulative thresholds. 2) A refined modeling approach using the exhaust parameters, locations and emissions to conduct modeling in AERMOD and HARP2 to determine if the cumulative thresholds are exceeded. Consultant will prepare an Air Quality Technical Report that will include the description of the existing conditions, a brief summary of the regulatory framework that guides the decision-making process, thresholds for determining impact significance, analysis of impacts, mitigation measures if needed, and level of significance after mitigation. The emission estimates, supporting calculations, model inputs and outputs will be included as an appendix to the Air Quality Technical Report. Deliverables and Schedule The technical analysis will be presented to City as a draft report in Word and PDF formats. The Consultant will complete the draft report 6 weeks after receiving the requested project data. ATTY/AGR/2019/AMENDMENTS/AMEND NO.1 - AECOM REV: 06-17-19 PR Page 7 of 22 34