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approximately 5 dBA. To compensate for the lower air flow, the timing for a car to be dried
<br /> would increase from 60 seconds to 90 seconds. Table 4 also reflects the calculated noise levels
<br /> for the quiet dryers at various distances.
<br /> The chosen vacuum system for the 7-Eleven Car Wash Project was the IVS Power Vacuums,
<br /> which is manufactured by Industrial Vacuum Systems, Inc. Measured noise level data were
<br /> provided by the manufacturer at various distances and are also shown in Table 4. For the noise
<br /> data of the vacuum system, ambient noise levels from street traffic, etc., were approximately 65
<br /> dBA with the vacuum unit not running. In addition to the blower and vacuum noise data
<br /> provided us by the manufacturers, Table 4 shows the combined noise levels at various distances.
<br /> Using the data from Table 4 and carwash blower directivity information supplied by other
<br /> manufacturers, maximum (Lmax) levels for the AeroDry Systems blowers and the IVS Power
<br /> Vacuums combined systems were calculated at 30 feet in the various directions towards the
<br /> identified noise-sensitive receptors.
<br /> TABLE 4 Noise Levels for the AeroDry Systems, LLC, Blower, the IVS Power
<br /> Vacuums & the Combined Noise Levels
<br /> lw 1.�..3i.ua G�1`� G�. -ti"'
<br /> . 1 � r g 1 � 1 , a�.r n�
<br /> 1 1 r' I Y�i 1 1 tt 7 101. ,17-°``'7'" zrg.Y ,y,xrx.-n 2 7` �� ri..� k �s
<br /> v 1 W}G t ..:. .'a•a. -�-.r--�,.�tk .mss-. ,tri le �'!, r .i Wyk 1 i� 43.."" .'.;7,...,7..I l 1 i i , ;..1:,�.r
<br /> t t! '7 i }x � e x�e�s � tin, 1 � 1 r,� f
<br /> ,,;1:41,*-,� 1 - �ql;",,L7 C' ii}� i, rti.z 1 11111•9`.rF tf�'.0l!!;•:1 ;� r40! �H .` : y'{� ;n a
<br /> . 1 fit,.nd.°,ZOAA.`.,9 1.N:La4iLik 1 �p /Lt ,e� l': x r ti 4 .d Hitt' lF �r .� �.Y
<br /> n.;�Y.f1��a�1�'�'J141Y rt'4 t �f � i q � Lt, .
<br /> 5 feet 82.5 �>b.. � .a:b.�. .�,�.: ����.��.t+�, �'� `.
<br /> 77.5 -- "'
<br /> 10 feet 81.5 76.5 75.0 82.4 --
<br /> 20 feet 79.4 78.8
<br /> 74.4 72.0 80.1 76.4
<br /> 30 feet 75,9 70.9 67.0 76.4
<br /> 40 feet 73.4 68.4 72.4
<br /> 65.0 74.0 70.0
<br /> 50 feet 71.4 66.4 65.0 72.3
<br /> 68.8
<br /> To determine the more distant blower noise levels at the receptors, the rate of sound propagation
<br /> between the operations at 30 feet and the noise sensitive receptor locations was established. For
<br /> simple, single sources, such as fixed equipment, the divergence of the sound wave would be
<br /> hemispherical in nature, producing a reduction of 6 dB with each doubling of the distance. Other
<br /> effects can modify these fall-off rates, such as partial shielding from buildings or topography,
<br /> atmospheric attenuation of sound, ground absorption, and meteorological effects. These effects
<br /> almost always reduce the noise, in addition to that due to sound divergence. As most of these
<br /> effects would vary with time due to changing environmental conditions, the most conservative
<br /> approach would be to assume only attenuation due to divergence for outdoor activities. From
<br /> these propagation calculations, the maximum noise levels (Lmax) for the combined blower and
<br /> vacuum systems were estimated at each noise-sensitive receptor in the vicinity of the project site.
<br /> Table 5 summarizes these levels.
<br /> The hours of operation for the carwash would be limited to daytime hours (i.e., 7:00 a.m. to
<br /> 10:00 p.m.). A conservative estimation for the number of vehicles to be washed in a day would
<br /> be approximately 30 to 75 vehicles, with 80 vehicles in a day being considered a very successful
<br /> day of business. Each vehicle would take approximately I to 2 minutes per wash/dry cycle.
<br /> Considering these usage characteristics and the Lmax noise levels shown in Table 4, the resulting
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