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Veneklasen Associates New Lake Elmo Elementary School Noise Study; Lake Elmo, Minnesota Property Noise Measurement Summary; Veneklasen Project No. 8512-002 October 28, 2024; Page 4 of 9 Month Day, Year; Page 4 of 9 www.veneklasen.com closer to the nearby roadways and the average hourly levels are therefore generally louder unless influenced by higher amounts of gunfire activity. Note that the maximum hourly level at L1 is louder at L1 than all other positions due to gun fire activity. Acoustic Modelling To verify the accuracy of acoustic measurements at the positions noted above, Veneklasen created an acoustic model of the gun club and proposed school property. The 2023 version of the SoftNoise Predictor acoustic modelling software was used to build the noise propagation model, specifically using the ISO 9613 noise calculation method. This software allows the incorporation of geographical conditions across both sites, atmospheric affects, effects of existing structures, and other attributes that affect how sound levels change as they propagate from the gun club to the proposed school properties. Once all four noise monitors, as discussed above, were running, Veneklasen had club members conduct several test shots at each of the five shooting bays and conducted short-duration calibration measurements within 15-feet of each of these shooting locations. These measurements were used to show the accuracy of the acoustic model discussed above to verify that the terrain, foliage, atmospheric conditions, etc. were all modeled appropriately such that the model represented real-world measurement conditions. The maximum deviation between modelled analysis results versus measured results was 0.9 decibels at the L4 position, which is the furthest position away from the sound source and well within the acceptable margin of error for an acoustic model. As noted above, acoustical measurements took place in July of 2024 when the gun club is only open to the public on weekends. However, during the months of October and November, the club is open to the public seven days a week. Per conversations with gun club ownership, these months are the most populus and generally when they have the highest patronage. Once a suitable acoustic model was constructed, it was pertinent to evaluate anticipated noise level changes based on increased occupancy from summer to fall. This includes both the effects of increased number of people as well as higher caliber firearms. Acoustic models were created for each condition. Increased Occupancy The gun club does not track number of rounds fired per day. They do, however, track the number of patrons who attend per day and were able to provide Veneklasen with occupancy data for July of 2023, October through November of 2023, and July of 2024. Veneklasen utilized a formula to calculate the anticipated change in measured sound level based on changes in occupancy from summer to fall. This formula format is a logarithmic change formula used often in acoustics for other applications (e.g., changes in traffic noise): 𝛥[𝑐𝐵] =10 log10 𝑜𝑐𝑐𝑒𝑎𝑙𝑙 𝑜𝑐𝑐𝑟𝑢𝑙𝑙𝑒𝑟 To model the increases in measured noise level, Veneklasen input the occupancy data collected from July of 2024 and the fall of 2023 into the formula above. Figure 2 shows predicted noise with increased occupancy in the fall at the same measurement locations shown in Figure 1. Numeric results below are shown in one hour dBA values with a maximum value of 60dBA, which is below the allowable 63dBA criterion.