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(206) 378-0569 www.greenbusch.com
1900 W Nickerson St., #201, Seattle, WA 98119 2262 N Albina Ave., #340 Portland, OR 97227
Memorandum
DATE: November 17, 2022
TO: Olivia Wright – Lynx Consulting, Inc.
FROM: Justin Morgan, INCE
RE: SE06105A PT Anderson Lake/Pope Noise Study
INTRODUCTION
The intent of this Noise Study is to evaluate sound levels associated with the new
emergency back-up generator planned for installation at the T-Mobile SE06105A PT
Anderson Lake/Pope site (Site), located at 4938 Highway 20 in Port Townsend,
Washington. This Noise Study includes predicted sound levels at nearby properties and
an assessment of compliance with local noise regulations.
SUMMARY
Sounds produced by the emergency generator set are likely exempt from codified sound
limits under the Jefferson County Code Chapter 8.70.060. However, if it is found that the
generator must comply with sound limits, predicted sound levels are within regulatory
sound limits at all nearby properties without the inclusion of additional noise mitigation.
ZONING AND REGULATORY CRITERIA
The Site and all nearby properties are within unincorporated Jefferson County; therefore,
the Jefferson County Code (JCC) will govern noise emissions from the Site.
The JCC Chapter 8.70 is a public disturbance noise ordinance with no quantifiable sound
level limits. However, sounds originating from a property that exceed the sound limits
permitted under Chapter 173-60 of the Washington Administrative Code (WAC) are
considered a “public disturbance noise” under JCC Chapter 8.70.050(1). Furthermore,
JCC Chapter 18.42.090(1)(g) prohibits noise created by wireless facilities from exceeding
the sound limits set forth in the WAC.
The frequent, repetitive, or continuous noise from starting, operating, repairing, or testing
any internal combustion engine is prohibited between the hours of 10:00 PM and 7:00
AM Sunday through Thursday and 11:00 PM and 7:00 AM on Friday and Saturday under
JCC Chapter 8.70.050(3). Therefore, it is recommended that testing and exercising the
generator set occur outside of these hours.
JCC Chapter 8.70.060 provides the following exemptions which may apply to the Site:
November 17, 2022
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SE06105A PT Anderson Lake/Pope Noise Study
(206) 378-0569 www.greenbusch.com
1900 W Nickerson St., #201, Seattle, WA 98119 2262 N Albina Ave., #340 Portland, OR 97227
JCC Chapter 8.70.060(8) – “Emergency equipment and work necessary in the
interests of law enforcement or for the health, safety, or welfare of the community”
JCC Chapter 8.70.060(10) – “The installation or repair of essential utility services
or work necessary to protect the public health, safety, or welfare”
JCC Chapter 8.70.060(11) – “Generators during periods when there is no electrical
service available from the primary supplier due to power outage, where a generator
is the only available source of electrical power, and the normal periodic testing of
generators during daylight hours”
JCC Chapter 8.70.060(19) – “Sounds exempted under Chapter 173-60 WAC, as
the chapter now exists or as it may hereafter be amended”
o WAC 173-60-050(4)(f) provides the following exemption from codified
sound limits “Sounds created by emergency equipment and work necessary
in the interests of law enforcement or for health safety or welfare of the
community.”
Under the exemptions provided by the JCC Chapter 8.70.060, the emergency backup
generator set proposed for installation at the Site is exempt from codified sound limits.
However, it is unclear if Chapter 18.42.090(1)(g) includes the exemptions provided by
JCC Chapter 8.70.060 and WAC 173-60-050(4)(f), or if sounds from the generator must
comply with sound limits defined in the WAC.
It is likely that generator set is exempt, however, as a conservative measure this analysis
assumes that operation of the generator set must comply with WAC limits. Details
regarding the WAC 173-60 are provided below.
Sound limits in the WAC are based upon the Environmental Designation for Noise
Abatement (EDNA) classification of the property containing the sound source and the
EDNA classifications of the properties receiving the sound. EDNA classifications in the
WAC are based on present, future, and historical land use, and take into consideration
the usage of other properties in the vicinity. EDNA classifications are defined in WAC 173-
60-030 as follows:
Class A EDNA – Lands where human beings reside and sleep. Typically, Class A
EDNA will be the following types of property used for human habitation:
o Residential
o Multiple family living accommodations
o Recreational and entertainment (camps, parks, camping facilities and
resorts)
o Community service (group homes, assisted living facilities, hospitals, health
and correctional facilities)
November 17, 2022
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SE06105A PT Anderson Lake/Pope Noise Study
(206) 378-0569 www.greenbusch.com
1900 W Nickerson St., #201, Seattle, WA 98119 2262 N Albina Ave., #340 Portland, OR 97227
Class B EDNA – Lands involving uses requiring protection against noise
interference with speech. Typically, Class B EDNA will be the following types of
property:
o Commercial living accommodations
o Commercial dining establishments
o Motor vehicle services
o Retail services
o Banks and office buildings
o Miscellaneous commercial services, property not used for human habitation
o Recreation and entertainment, property not used for human habitation
(educational, religious, governmental, cultural and recreational facilities)
Class C EDNA – Lands involving economic activities of such a nature that higher
noise levels than experienced in other areas is normally to be anticipated. Persons
working in these areas are normally covered by noise control regulations of the
department of labor and industries. Uses typical of Class A EDNA are generally
not permitted within such areas. Typically, Class C EDNA will be the following
types of property:
o Storage, warehouse, and distribution facilities
o Industrial property used for the production and fabrication of durable and
nondurable goods
o Agricultural and silvicultural property used for the production of crops, wood
products, or livestock
Maximum permissible sound levels are defined in WAC 173-60-040 and are shown in
Table 1.
Table 1. WAC Sound Limits, dBA
EDNA of Noise
Source
EDNA of Receiving Property
Class A Class B Class C
Class A 55 57 60
Class B 57 60 65
Class C 60 65 70
Source: WAC Chapter 173-60-040
Modifications to the sound limits shown in Table 1 are also identified in WAC 173-60-040.
These modifications include a 10 dB reduction to permissible sound levels received at
Class A EDNA properties between 10:00 PM and 7:00 AM.
The Site and properties south and east of the Site are undeveloped and zoned
Commercial Forest (CF-80) and Inholding Forest (IF-20) and are considered Class C
EDNA. The parcel directly north of the proposed generator location is also currently
undeveloped and zoned Inholding Forest (IF-20). Properties north and west of the Site
are zoned Rural Residential (RR-5 and RR-10) and Rural Forest (RF-40). Many of these
parcels contain single-family homes and are considered Class A EDNA. The zoning and
EDNA classifications of nearby properties are shown in Figure 1. The resulting sound
limits for noise emanating from the Site and received at Class A EDNA properties are 60
November 17, 2022
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SE06105A PT Anderson Lake/Pope Noise Study
(206) 378-0569 www.greenbusch.com
1900 W Nickerson St., #201, Seattle, WA 98119 2262 N Albina Ave., #340 Portland, OR 97227
dBA during the day (7:00 AM to 10:00 PM) and 50 dBA at night (10:00 PM to 7:00 AM).
The sound limits at Class C EDNA properties are 70 dBA at all times. If the exemptions
provided by the JCC Chapter 8.70.060 are determined to not apply to the Site, then sound
emissions from the emergency generator would need to comply with these sound limits.
Figure 1. Jefferson County Zoning and EDNA Classifications
ACOUSTICAL MODEL
The primary tool used to predict sound levels at nearby properties was the 3-D computer
noise modeling software environment, Cadna/A. Cadna/A utilizes the CADNA (Control of
Accuracy and Debugging for Numerical Applications) computation engine developed by
the Pierre et Marie Curie University of Paris. The model used for this project utilized the
International Organization for Standardization 9613 Part II algorithms, implemented in the
Cadna/A software, which accounted for the effects of distance, topography, and surface
reflections on sound levels. The acoustical model is typically accurate to within 3 dB.
Conservative assumptions were used in the model created for this project to ensure
sufficient design margin within the predicted sound levels. Therefore, predicted sound
levels can be compared to applicable criteria directly, without consideration of additional
design margin.
The location of the generator was determined from drawings provided by Lynx Consulting,
Inc. Property line locations were obtained from Jefferson County Geographical
Information System data downloaded in November 2022 and topographical information
was based on 2019 Washington State LIDAR data.
November 17, 2022
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SE06105A PT Anderson Lake/Pope Noise Study
(206) 378-0569 www.greenbusch.com
1900 W Nickerson St., #201, Seattle, WA 98119 2262 N Albina Ave., #340 Portland, OR 97227
ANALYSIS
The generator was placed in the computer noise model based on the location shown in
the drawings provided by Lynx Consulting, Inc. Sound data for the 48-kW generator
housed in an enclosure were published by Generac, and provided to our office by Lynx
Consulting, Inc. Sound data for the emergency generator is shown in Table 2.
Table 2. Generator Sound Pressure Level
Equipment Sound Pressure Level at 23 Feet
Generac RD048 3.4L
G0071940 Diesel Generator 65 dBA at rated load
Source: Generac
RESULTS
Predicted sound levels at adjacent properties are shown in Table 3 and predicted sound
levels 5-feet above grade are illustrated in Figure 2. These predicted sound levels do not
include contributions from the existing or future ambient noise environment, or any
existing equipment installed at the Site.
Table 3. Predicted Sound Levels, dBA
Property Line Project Sound
Limit (day/night)1
Predicted Sound
Level
North 60/50 3
North of Generator Location 70/70 56
South 70/70 35
East 70/70 14
West 60/50 33
1. The sound limits shown do not apply if the generator is exempt from sound limits under JCC Chapter
8.70.060
November 17, 2022
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SE06105A PT Anderson Lake/Pope Noise Study
(206) 378-0569 www.greenbusch.com
1900 W Nickerson St., #201, Seattle, WA 98119 2262 N Albina Ave., #340 Portland, OR 97227
Figure 2. Predicted Sound Levels
Although sounds from the emergency generator set are likely exempt from regulatory
criteria under JCC 8.70.060, sound levels are predicted to comply with WAC daytime and
nighttime sound limits at all nearby properties.
CONCLUSION
Sound created by the emergency generator is likely exempt from codified sound limits.
However, if it is determined that the generator must adhere to the sound limits defined in
the WAC, sound from the generator is predicted to comply with WAC sound limits at all
nearby properties. No additional noise mitigation is required.
Respectfully submitted;
Justin Morgan, INCE
Lead Noise & Vibration Consultant