75D - PH ZONING ORD AND CUP CALIFORNIA PALMS

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TABLE S NOISE LEVEL MEASUREMENTS i'EIdSUS PRF.D7CTEn MnnFr. uFCrtr Te Monitorln Location NR-3 (Soft Site) Measured dBA 67 9 Modeled Le (dBA ~ 67.4 Di erence (dBA 0.5 . NR-3 (Hard Site) 69.2 1.3 Modeling of Existing 71"ajy1C Volumes Noise within the project azea is dominated by vehicles traveling along Harbor Boulevazd. In order to assess the potemial for mobile-source noise impacts, it is necessary fo determine the noise currently generated by vehicles traveling through the area. Average daily traffic volumes (AD'I) are based on data provided by Bob Kahn of RK Engineering Group as per his discussion with the Orange County Transportation Authority (OCTA). Mr. Kahn reports that OCTA estimates that Harbor Boulevazd currently carries 42,000 ADT and could carry 47,000 ADT at General Plan build out. To determine the CNEL noise level produced by this traffic, the percentage contribution from each hour of traffic was determined from an Orange County, year 2005 model run of the California Av Resources Boazd's EMFAC2002 computer model used in the projection of vehicle emissions. The model predicts the volume of vehicles and miles generated for each of the 24 hours of the day. The ratio of each hour of traffic to the total daily traffic was then calculated from the model data. Traffic between the hours of 7:00 p.m. and 10:00 p.m. was assigned a 5-dBA penalty whereas the traffic predicted between 10:00 p.m. and 7:00 a.m. was assigned a 10-dBA penalty. The resultant noise associated with each hour was then logarithmically summed and averaged so that a "correction" factor could be ascertained and applied to the entire vohune of traffic as if it were to occur in a 1-hour period. Under these premises, this CNEL value is 10.2 dBA less than the model results that are predicted if the entirety of the ADT volume were modeled to occur in a 1-hour period. As such, the CNEL can be represented by modeling the ADT as if it were to occur in a 1-hour period and subtracting 10.2 dBA from the resultant value. For the purposes of this analysis, the ratio of automobiles, medium trucks, and heavy trucks is based on the vehicle counts observed along Harbor Boulevazd in the field study during noise reading NR-3. In all, 597 vehicles were coumed during the field reading. Of these vehicles, 571(95:64 percem) were autos, 22 (3.69 percent) were medium trucks, and four (0.67 perceut) were heavy trucks. Vehicle speeds are based on the posted speed limit of 40 mph. Table 6 presents the projected noise level along Harbor Boulevard, as well as the distances to the 70, 65, and 60 dBA CNEL noise contours. The modeling assumes "soft" site conditions that shows a better correlation with field observation. Based on the distance to the proximate on-site structures (approximately 65 feet from the cernerline of the road), exterior noise at the nearest rooms is approximately 71 dBA CNEL. Based on the measurements obtained in Room 462, the stnrcture is estimated to provide approximately 20 dBA of attenuation. TABLE 6 EXISTING TRAFFIC-GENERATEDNOISELEYELS THROUGHTHEPItO.IECTAREA' Existing Sristing Distance Distance Distance Street Name Location Speed (mph) ADT CNEL (dBA to 70 io 65 to ti0 Volumes @ 50 Feet) CNEL CNEL CNEL Harbor Boulevazd S/O McFadden 40 42,000 72.4 (Feet 73 Feet) 156 Feet 335 1 A.. ~___ __~ c._.. _ ~_.. aaa`uayycu ualui tIIG t%GIILGIime Or me rOaa. II 75D-131