HomeMy WebLinkAbout713013001 Acoustical Study(rLS�acoustics
November 4, 2015
Mariah Stevens
Ryka Consulting
918 South Horton Street Suite 1002
Seattle, WA 98134
Re: Acoustical Report — T -Mobile SE05630A US 101 Dowans Creek/ATC
Site: 846 Dowans Creek Road, Forks, WA 98331
Dear Mariah,
This report presents a noise survey performed in the immediate vicinity of the proposed
T -Mobile telecommunications facility at 846 Dowans Creek Road in Forks, 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 exterior ambient noise levels were measured on site with a Larson -Davis 820 sound level
meter on November 3, 2015. Measurements were conducted on site in accordance with the State
of Washington code for Maximum Environmental Noise Levels WAC 173-60-020. The average
ambient noise level was 42 dBA.
Code Requirements
The site is located within the Jefferson County Zoning jurisdiction on property designated with a
CF (Commercial Forestry) zoning. The nearest receiving properties are also zoned CF. WAC
173-60 identifies agricultural properties used for the production of crops, wood products or
livestock Class C EDNA.
The proposed new equipment consists of equipment support cabinets, which are expected to
run 24 hours a day.
According to Jefferson County Code Chapter 18.42.090.1.g noise generated by a wireless
facility shall not exceed the maximum environmental noise levels set forth WAC 173-60.WAC
173-60 limits noise from equipment on a Class C EDNA property as follows:
Class C EDNA Receiver: Noise is limited to 70 dBA 24 hours a day.
222 Etruria Street. Suite 100
Seattle, WA 98109
P: 206.839 0619
T -Mobile Page 2
SE05630A US 901 Dowans Creek/ATC
Predicted Equipment Sound Levels
The equipment includes (1) Purcell RAC57 Power Cabinet.
The following table presents a summary of the equipment and their associated noise levels:
Table t
The equipment will be located at grade within an equipment compound surrounded by a chain
link fence. The nearest receiving property is approximately 230 feet south of the equipment
location.
To predict equipment noise levels at the receiving properties, this survey uses the methods
established by ARI Standard 275-2010 and ASHRAE. Application factors such as location,
height, and reflective surfaces are accounted for in predicting the sound pressure level.
The predicted sound levels at the nearest receiving property is shown below in Table 2 below.
Table 2
ADDlication Factors and Predicted Noise Levels
1 Equipment Sound Pressure Level of 5 ft. (dBA), L 1 68
2 Distance Factor (DF) -33
Inverse -Square Law Free Field): DF = 2010 d1/d2 230 k
3 New Equipment Sound Pressure Level at Receiver, Lpr 35
Add lines 1 —2
As shown in Table 1, the sound pressure level from the proposed equipment will meet the 70 dBA
code limit at the nearest receiving property.
Please contact us if you have any questions or require further information.
Sincerely,
SSA Acoust' s, LLP
Alan Burt, P.E.
ASSOCIATE PARTNER
ACOUSTICAL CONSULTANT