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I ~ I I I I I I . I I I I I I I. I I "!z., The CO monitoring analysis requires numerous assumptions regarding meteorology and vehicle operations. The following modeling assumptions are generally considered to be worst case assumptions for this type of analysis. o Wind speed of 1.0 meters per second. o Analysis of 36 wind directions at 10 degree increments o Ambient temperature of20 degrees Fahrenheit o Atmospheric stability class D o 20.6 percent of vehicles operating in a cold-start mode and 27.3 percent of vehicles operating in a hot start mode. o The analysis utilized year 2000 emission factors to represent the first year of operation of any portion of the business park, o Vehicle age mix consistent with Metropolitan area 1990 vehicle registration. o Vehicle type mix was the national average mix taken from the MOBll.E5a model. o One-hour average CO concentrations are predicted based on the PM peak hour traffic volume forecasts documented in the traffic section, o Eight-hour average CO concentrations are predicted based on the peak one-hour concentrations, multiplied by a persistence factor of 0.7. The persistence factor accounts for the lack of persistence of the worst-case meteorological conditions for eight consecutive hours. o The analysis assumes the roadway improvements documented in the traffic section. Analysis was conducted of both the CR I and CR J interchanges with 1-35W. These interchange areas will experience the highest traffic volumes in the vicinity of the project and will therefore have the highest CO concentrations. Receptor sites were selected in the vicinity of each interchange to represent locations where people may be present for time periods consistent with air quality standards. The receptor sites are described below: Receptor RI - Truck terminal north of CR J between 1-35W and the 1-35W west service drive Receptor R2 - Proposed retail development south of CR J, east of the northbound off-ramp from 1-35W Receptor R3 - Truck terminal north of CR J, east of the northbound off-ramp from 1-35W Receptor R4 - Residence north of CR I, east of the west 1-35W ramp terminal Receptor R5 - Residence north of CR I, just west of 1-35W Receptor R6 - Trailer home south of CR I, west of the 1-35W southbound on-ramp. The results of the analysis are shown in the following table. WISP ARK Rice Creek Corporate Park Draft EIS December 10, 1998 Page 79