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HomeMy WebLinkAboutEXHIBIT_055q{ Williamson Marijuana Growing Facility February 20,2020 Page I of4 ffc0il$lr[$ lIt February 20,2020 Bricklin & Newman, LLP 1424 Fourth Avenue, Suite 500 Seattle WA 98101 Subject Williamson Marijuana Growing Facility Noise Study Review Ladies & Gentlemen: This letter presents peer review comments on the January 16,2020 environmental noise study prepared by The Greenbusch Group. As stated in the report introduction, the purpose of the Greenbusch study was to evaluate the noise levels associated with the fans planned for the marijuana growing and processing facility. The conclusion of the Greenbusch noise study is that no noise mitigation is required. Based on my review of the Greenbusch noise study, I cannot agree with the conclusion that noise mitigation is not required. My conclusion is based on the following facts: The project site and the adjoining properties to the north, east, and south are all zoned rural residential. The maximum allowable noise levels are specified in WAC 173-60, and the allowable noise levels are based on the site zoning, not on the site use. Therefore, the maximum allowable noise level from this project on adjacent property is 55 dBA during the day and 45 dBA at night (defined as l0 PM to 7 AM). Table 7 of the Greenbusch noise study presents a predicted noise level of 47 dBA at the south property line, which (if accurate) exceeds the noise ordinance nighttime limit by 2 dBA. 2. Existing sound levels were measured at the site from Tuesday, January 7 to Friday, January 10,2020. The problem with the noise measurements is that they were collected in the wrong location. Figure 2 of the Greenbusch noise study indicates that the measurements were taken near Coyle Road. The noise study report does not indicate the distance from the measurement microphone to Coyle Road, but Photo I makes it appear that the distance was less than 50 feet from the road centerline. This is not an acceptable noise measurement location, because it is too close to the road. When the road traffic is the primary ambient noise source (as confirmed by the paragraph below Figure 3), the noise level will decrease by at least 6 dB every time the distance to the roadway is doubled. Therefore, it is 5266 NW Village Park Drive Issaquah, WA 98027 (425) 649-9344 (voice) emai I : jerry@j glacoustics.com JGL Williamson Marij uana Growing Facility February 20,2020 Page 2 of 4 Ic0tlsttE$ ilrI likely that the ambient noise level at the location of a future home on the lot north and south of the proposed project will be substantially lower than the sound levels presented in Table 5 and Figure 3. For example, the existing homes on the east side of Coyle Road are located 350 feet east of Coyle Road and 500 feet west of Blueberry Hill Drive. Clearly, these homeowners do not want to put their homes close to the roadway. It is therefore reasonable to assume that future homes built on the properties north and south of the proposed site could easily place their homes at least 350 feet from Coyle Road. If the existing ambient noise measurements shown in Figure 3 were taken at a distance of 50 feet from Coyle Road, then we can expect that the daytime ambient noise level at these future homes would be about l7 dBA lower than the levels presented in the Greenbusch noise study. In that case the daytime average noise levelof approximately 62 dBA near Coyle Road would actually be 45 dBA or less at a future home site. In the nighttime hours noise levels would be even lower. These ambient noise levels are low enough so that noise from the ventilation fans could easily be audible at these future residential locations. 3. There is insufficient information presented in the ANALYSIS section of the Greenbusch noise study (pages 8-9) to verify that the analysis and predicted noise levels from the proposed fans are accurate. The second sentence ofthe first paragraph in the ANALYSIS section indicates that the analysis assumes that there will be a minimum of 5 feet of acoustically lined ductwork with an elbow on two of the fans (SF-l and SF-2). It does not indicate the size of these ducts, the ihickness of the duct liner, or whether the lining is on one or both sides of the fan. Without these details it is not possible to determine the noise mitigation that will be provided by this ductwork. I must point out that the conclusion of the Greenbusch noise study is that no noise mitigation is required, yet the analysis assumes noise mitigation (lined ductwork with elbows) on two of the fans. 4. According to Table 4, SF-l is one of the smaller fans (FKD l4) and SF-2 is one of the larger fans (FKD l6). This does not make any sense. If the elbow and duct liner provide sound attenuation, I would think that it would be applied to the two larger fans (FKD l6). I am guessing that Table 4 is in error, and all ofthe EF fans should be the smaller fans (FKD l4) and SF-l and SF-2 would both be the larger fans (FKD l6). This error should be corrected. Figure 3 shows the predicted noise contours in color coded zones from the 8 fans. It appears that the two fans at the west end of the building that is oriented east-west in the center of the property generate the highest noise levels (note the red and yellow colored areas). According to Figure 2, these two fans are SF-3 and SF-4, which are two of the smaller fans. The larger (and noisier) fans (SF-l and SF-2) are shown as located at the south end of the building oriented north-south. This, however, conflicts 5266 NW Village Park Drive Issaquah, WA 98027 (425) 649-9344 (voice) emai I : j erry@j glacoustics.com JGL I Williamson Marijuana Growing Facility February 20,2020 Page 3 of4 0c0tslt[$ lllI with the noise contours presented in Figure 3. This leads me to suspect that SF- I and SF-2 were originally located as shown in Figure 2,but had to be moved to the other building to avoid excessive noise at the south property line. Besides, it does not make sense that one building would have both of the noisy fans and the other building would have none of the noisy fans. I am guessing that a mechanical engineer has not been involved to assist in the facility design. 5. The noise analysis does not show any noise radiating from the two buildings. There are no architectural drawings showing the exact location and construction of these buildings, so there is no way of calculating the noise radiated from these structures. I must assume that these buildings will have doors and ventilation openings in the roof which can radiate noise. I suspect that these buildings will also require heat. In a previous project in which I was hired to prepare a noise study for a similar facility, I found that the gas-fired heaters were a major noise source that had to be considered. It appears that this important element has been totally neglected. In my professional opinion, this noise study must be completely redone if compliance with the noise ordinance is to be ensured and if the noise impact is to be fully mitigated The revised noise study should include: l. A correct assessment of the source property zoning (EDNA Class A), 2. Ambient noise measurements conducted at least 350 feet from Covle Road with the results showing the hourly L.q, L.*, Lqo, and the Lan. 3. Fan noise levelpredictions based on the correct fan size and fan location with calculated sound power levels based on ductwork (if any) shown on the mechanical drawings, 4. Calculation of noise radiated by the two buildings. This would require architectural drawings of the two buildings showing the proposed construction, location of doors and ventilation openings and the location of heaters and humidifiers, 5. Predicted noise levels at the north and south property lines from trucks, tractors, and other vehicles on the site. While noise from motor vehicles is exempt from the noise ordinance while the vehicles are operated on public highways, they are not exempt from the noise ordinance while operating on private property, 5266 NW Village Park Drive Issaquah, WA 98027 (42s) 649-9344 (voice) email : j erry@j glacoustics.com JGL JGL f Williamson Marijuana Growing Facility February 20,2020 Page 4 of 4 tt0llslt[$ lIE 6. Predicted noise levels with and also without the recommended mitigation, and 7. A clear and full description of the recommended noise mitigation. Without a totally revised noise study as described above, there is no way to ensure that the proposed project will not adversely impact the surrounding property and be in compliance with the noise ordinance. If you have any questions regarding these review comments, do not hesitate to contact me at my office. Very truly yours, JGL Acoustics, Inc. &", @ e.ti,0n Jerry G. Lilly, P.8., FASA President Member INCE (Bd. Cert.), ASHRAE, ASTM, NCAC 5266 NW Village Park Drive Issaquah, WA 98027 (425) 649-9344 (voice) email: jerry@jglacoustics.com