SSA Letter 09182009SSA. _
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September 18, 2009
Mr. Paul Long
Site Acquisition Coordinator
Goodman Networks
8815 122nd Avenue NE
Kirkland, WA 98033
Re: Acoustical Report — AT &T WA580 Yelm
Site: 11247 Morris Road SE, Yelm, WA 98597
Dear Paul,
This report presents a noise survey performed in the immediate vicinity of the proposed
AT &T telecommunications facility at 11247 Morris Road SE in Yelm, Washington. This noise
survey extends from the proposed equipment to the nearest properties. The purpose of this
report is to document the existing conditions and the impacts of the acoustical changes due
to the proposed equipment. This report contains data on the existing and predicted noise
environments, impact criteria and an evaluation of the predicted sound levels as they relate
to the criteria.
Ambient Conditions
Existing ambient noise levels were measured on site with a Larson -Davis 820 sound level
meter on September 16, 2009. Measurements were conducted as close to the proposed
location as possible and the property lines in accordance with the State of Washington code
for Maximum Environmental Noise Levels WAC 173 -60 -020. The average ambient noise
level was 41 dBA, due primarily to a light breeze. The weather during the measurements
was overcast with no precipitation.
Code Requirements
The site is located within the Thurston County Zoning jurisdiction. The site is on Rural
Residential property. The nearest receiving property is also Rural Residential.
The proposed new equipment consists of equipment support cabinets, which are expected to
run 24 hours a day.
Thurston County Code Chapter 21.57.030 incorporates Washington Administrative Code
Chapter 173 -60 in its entirety by reference, and further designates all residences as Class A
EDNA. Under WAC 173 -60, noise from equipment on a Class A EDNA (Residential)
property is limited as follows:
SSA Acoustics, LLP
222 Etruria Street, Ste 100
Seattle, Washington 98109
t. 206.839.0819 f. 206.839.0824
AT &T Wireless
WA580 Yelm
Class A EDNA Receiver: Noise is limited to 55 dBA during daytime hours. During nighttime
hours, between the hours of 10 p.m. and 7 a.m., the maximum permissible sound level is
decreased by 10 decibels. Since the support cabinets are expected to operate 24 hours a
day, they must meet the 45 dBA nighttime limit.
Predicted Equipment Sound Levels
The proposed equipment includes one AT &T Wireless UMTS Cabinet and three Argus TE -40
Cabinets. According to manufacturer data, the AT &T Wireless UMTS iBTS Outdoor Cabinet
has a sound pressure levels of 58 dBA at 3 feet and the Argus TE -40 Outdoor Battery
Enclosure produce a sound pressure level of 64 dBA at 3 feet. The total sound pressure
level from all four cabinets is 69 dBA at a distance of 3 feet.
To predict equipment noise levels at the receiving properties, this survey used the methods
established by ARI Standard 275 -97. Application factors such as location, height, and
reflective surfaces are accounted for in predicting the sound level at the nearest receivers.
The equipment cabinets are to be located on a concrete equipment pad within an existing
equipment compound. The nearest receiving property is approximately 240 feet west of the
equipment location. The predicted sound level at the nearest property is shown in Table 1
below.
Table 1
Application Factors and Predicted Noise Levels
Proposed New Equipment
Line
Application Factor
West
1
Combined Sound Pressure Level at 3 ft. (dBA), L 1
69
2
Distance Factor (DF)
-38
Inverse-Square Law Free Field): DF = 20lo d1 /d2
240 ft
3
New Equipment Sound Pressure Level at Receiver, Lpr
Add lines 1 and 2
31
As shown in Table 1, the combined sound pressure level from the proposed equipment
cabinets at the nearest receiving property is predicted to be 31 dBA. This complies with the
45 dBA night -time noise limit to a residential property. Since the equipment noise will be
loudest at the nearest receiving property line, we predict that the noise levels will not exceed
code limits at all other receiving property lines.
Please contact us if you have any questions or require further information.
Sincerely,
SSA Acoustics, LLP Reviewe by,
Joel Esselstrom
Senior Technician
Page 2
Alan Burt
Acoustical Consultant