2 - EIR18-01; DA18-01; GPA18-06; AA18-10_2525 N MAIN STREET

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TABLE 1: REFERENCE NOISE LEVEL MEASUREMENTS Noise Source Duration (hh:mm:ss) Ref. Distance (Feet) Noise Source Height (Feet) Hourly Activity (Mins)7 Reference Noise Level (dBA L50) @ Ref. Dist. @ 50 Feet Roof-Top Air Conditioning Unit1 96:00:00 5' 5' 39 74.4 54.4 Trash Enclosure Activity2 00:00:32 5' 5' 60 69.0 49.0 Pad-Mounted Transformer3 -3 6' 5' 60 56.0 37.6 Parking Lot Vehicle Movements4 01:00:00 10' 5' 60 44.0 33.5 Courtyard Activity5 00:08:00 10' 4' 60 73.8 59.8 Outdoor Pool/Spa Activity6 00:10:00 5' 4' 60 68.7 48.7 Roof-Top Parking4 00:10:00 5' 4' 60 68.7 48.7 1 As measured by Urban Crossroads, Inc. on 7/27/2015 at the Santee Walmart located at 170 Town Center Parkway. 2 As measured by Urban Crossroads, Inc. on 5/3/2018 at a commercial and office park trash enclosure in the City of Costa Mesa. 3 Source: NEMA TR 1-2013 Transformers, Step Voltage Regulators and Reactors, Table 2 sound level for a 500 kVA transformer. 4 As measured by Urban Crossroads, Inc. on 8/24/2016 in the parking lot of the Windemere Apartment community in the City of Riverside. 5 As measured by Urban Crossroads, Inc. on Saturday night, September 21, 2019 in the City of Newport Beach. 6 As measured by Urban Crossroads, Inc. on 7/5/2017 at the Covenant Hill Clubhouse pool in Ladera Ranch. 7 Anticipated duration (minutes within the hour) of noise activity during typical hourly conditions expected at the Project site based on the reference noise level measurement activity. The basic noise attenuation equation shown below is used to calculate the distance attenuation based on a reference noise level (SPL1): SPL2 = SPL1 - 20log(D2/D1) Where SPL2 is the resulting noise level after attenuation, SPL1 is the source noise level, D2 is the distance to the reference sound pressure level (SPL1), and D1 is the distance to the receiver location. Table 2 indicates that the hourly noise levels associated with the roof-top air conditioning units, trash enclosure activity, pad-mounted transformers, parking lot vehicle movements, outdoor courtyard activity, outdoor pool/spa activity and roof-top parking activities are expected to range from 31.4 to 46.9 dBA L₅₀ at the sensitive off-site receiver locations. The operational noise level calculation worksheets are included in Appendix A and include barrier attenuation provided by intervening structures between each noise source and the receiver locations, where applicable, from the existing noise barriers and planned Project buildings. 2-191