PZ - Winco Chinden Linder Noise AnalysisMULLINS
ACOUSTICS
October 31, 2018
Ronald R. Schrieber II
Project Manager
Winco Foods
650 N. Armstrong Place
Boise, ID 83704
architectural
environmental
and industrial
noise control
Subject: New Store, Meridian, ID -- Noise Analysis project # 3737
Dear Ron:
I performed a noise study for this proposed store at Chinden and Linder Roads in
October 2017. Since the original noise report was prepared, the site has been
redesigned, now placing the Winco store closer to Linder Road. This also puts the
loading dock considerably further from homes and in a much more favorable orientation.
You asked me to review the new design and revise my report accordingly, for
submission to the City of Meridian.
The new store will be located on the southwest corner of the lot, closer to North Linder
Road. The Winco store will be part of a larger shopping center development. The entire
parcel will be annexed into the City of Meridian as part of the approval process. The store
setback from the near edge of Linder Road is 255 feet to the corner of the building. Homes
to the west across Linder Road (on West Rattlesnake Court) are located about 340 feet
west from the Winco store location, and their backyards are set back from the near edge of
Linder Road only by about 50 feet. These homes are close to the fire station and some are
close to existing pad stores that are not part of this new development located along Chinden
Boulevard (Dollar Store, coffee shop, Sprint, etc),
There are existing residential neighborhoods (along Bacall Street and N. Arliss Avenue) are
about 371 feet to the nearest corner of the new store building, and on a slant distance of
581 feet from the trash compactor corner of the building. The store building itself will further
act as a very effective noise barrier protecting these homes.
This analysis still focuses on the Arliss and Bacall homes, since they are considerably
closer to the store. Homes to the west of Linder Road are much closer to the road and will
be far more affected by traffic noise on Linder Road and by noises associated with the fire
station, than by noise associated with a new Winco store. Meridian Fire Department station
#5 is located near those homes, with direct driveway access onto Linder Road.
The primary concern is how much noise the store might make at nearby homes, including
loading dock operations and delivery trucks, and how that compares to pre-existing noise
levels in the area from traffic on these major arterial roadways.
10400 Overland Road #211 -- Boise, ID 83709
www.mullinsacoustics.com 208-514-6264
SUMMARY
Noises from the loading dock are expected to be considerably less than the current ambient
sound levels in the area. When the new noise is comparable to or less than the pre-existing
noises, that is generally considered to create no adverse noise impact.
At the Arliss homes, noise levels from the loading dock are predicted at Leq = 28 dBA and
L10 = 31 dBA. At the Rattlesnake Drive homes, loading dock noise levels are predicted at
Leq = 31 dBA and L10 = 34 dBA. (See definitions on last page).
Ambient noise in the area is Leq = 45-53 and L10 = 59 dBA during the early morning hours,
for comparison.
Since the predicted noises associated with the store will be at least 8 decibels below
the typical ambient noises, we conclude that there will be no adverse noise impact on
the nearby homes. Most store noises will be inaudible versus the ambient
conditions.
NOISE ORDINANCE
The City of Meridian has noise requirements stipulated in Municipal Code section 6-3-6,
titled "NOISES CREATING PUBLIC DISTURBANCE". Specific language includes:
A. Prohibited Acts:
Between the hours of eleven o'clock (11:00) P.M. and six o'clock (6:00) A.M., or at
any time so as to unreasonably disturb or interfere with the peace, comfort or
enjoyment of others, it is unlawful for any person to cause, or for any person in
possession of property to allow to originate from such property, sound that is a public
disturbance noise. The following sounds are determined to be public disturbance
noises:
4. Noise From Buildings: The creation of frequent, repetitive or continuous sounds
which emanate from any building, structure, apartment, or condominium, or from any
fixture or apparatus attached thereto, which unreasonably interfere with the peace,
comfort, and repose of owners or possessors of real property....
B. Exceptions:
6. Sounds caused by safety warning devices required by law.
7. Sounds caused by devices or machinery that is part of the use within the confines
of the particular zoning designation that the device is located or pursuant to a
conditional use permit (i.e., drive-through window speakers, car lot PA systems).
In this case the receivers are single family homes. The facades of the nearest homes at
Bacall and Arliss will be located about 581 feet from the proposed loading dock and trash
compactor area. For homes located across Linder on Rattlesnake Drive, the distance from
the loading dock is 340 feet.
Exception B.6 exempts safety warning devices required by law, which would apply to
OSHA -mandated backup beepers on trucks and forklifts. B.7 could be interpreted to mean
that noises associated with a grocery store would be normally permitted in areas that are
zoned for such land uses which would be the case based on the future zoning.
The Meridian ordinance would be referred to in technical terms as a nuisance ordinance.
No numerical noise limits are stipulated, only that a noise should not "disturb a reasonable
person", or create a nuisance.
In the absence of stipulated numerical limits, we next compare the noises expected from the
store against the pre-existing ambient noises as a way to assess potential impact at the
nearest noise -sensitive location.
AMBIENT (BACKGROUND) NOISE
The pre-existing background noises are called the ambient noise environment. This area is
subject to noteworthy and continuous levels of traffic noise from both Chinden Road and
Linder Road, intermittent local traffic in the subdivisions, Rocky Mountain High School (the
football field lights were on and crowd noise as audible during the Monday evening site
visit), aircraft flyovers on approach or departure from Boise Airport, and occasional sounds
from the nearby fire station (Meridian Station #5).
Ambient noise was measured by placing a 24-hour data logging sound meter near the site,
located at the north end of Arliss Street, just north of Bacall, along the common property
line. The meter was placed on Monday afternoon SEP 25, 2017 and logged sound levels
hourly until after 4 pm on Tuesday SEP 26, 2017. The attached chart shows the Leq
(hourly average) the L10 (10% level) and the L90 (90% percent levels) logged during the
measurement. Definitions of these terms appear at the end of this report. The L10 is the
most salient data concerning assessment of loading dock noise.
In addition to the data logging meter, live observations (spot measurements) of sound were
made nearby using a second sound meter between 9:00 pm and 11:00 pm on Monday
evening, concurrent with the monitor. Live observations allow us to document the
momentary sound levels and sources of typically occurring noises in the area. The
following data was noted:
live observations
noise monitor
Leq L10 L90
Leq L10 L90
9 pm 46 51 42
45 47 41
10 pm 47 53 39
42 44 39
The discrepancy between the monitor and the spot measurement Leq during the 10 pm
hour was due to an ambulance siren passing by on Linder northbound within the last three
minutes of the measurement period. This single event skewed the Leq and L10 upward, in
part because the monitor position was partially shielded from ambulance noise by the
homes on Arliss as it travelled northbound on Linder. The logged data was also averaged
over the entire hour, versus a 30 minute average for the live observations, so the single
loud ambulance passby contributed more to the spot measurement average (Leq).
Spot measurements were also made during the 3-4 pm hour on Monday after the data
logging meter was programmed to begin. Both the afternoon and evening spot values
agreed quite well with the data logged on the 24-hour monitor near the homes.
Since the store is now closer to Linder, supplemental spot measurements were made at the
approximate setback of the nearest homes on Rattlesnake Court on Friday October 12,
2018. During the morning hour of 6-7 am on Monday October 15, 2018, traffic noise levels
were Leq = 55-57 dBA, and L10 = 59-61 dBA. Traffic on Linder dominated, but traffic on
Chinden determined the background noise "floor" or minimum noise levels. There was also
a noteworthy amount of local traffic in and out of this residential neighborhood on Gertie
Place after 6 am, not affiliated with the nearby businesses.
During the October 12, 2018 morning measurements, we also observed three garbage
trucks serving the dumpsters for various businesses along Gertie Place. There are already
garbage trucks and delivery trucks passing through the area for commercial purposes that
are not related to weekly trash service for homes.
The key data to consider is the L10 during the early morning hours, from 4 am to 7 am.
This is a time when the ambient traffic noise is minimal and when the loading dock will be
most active — the worst case acoustically. Loading dock noises tend to be of short duration
and intermittent, and are therefore best represented by the L10.
For this analysis the ambient levels at homes are:
on Arliss Street
L10
4 am 45 dBA
5 am 45
6 am 51
7 am 53
on Rattlesnake Court
L10
om
As the morning progresses, there is a natural increase in traffic counts on Chinden and on
Linder, with a corresponding increase in traffic noise approaching and during the peak
morning traffic hour and most daytime hours.
LOADING DOCK NOISE
Noise levels were measured at the loading dock behind an existing Winco store at 8200 W.
Fairview Avenue in Boise. Loading dock measurements were made on Wednesday SEP
27 between 4:45 am and 7:00 am. The typical noise level from loading dock activity
(including some truck arrivals and departures) was Leq 48 at 48 feet when measured for a
one-hour period.
We observed a number of semi -trucks and smaller straight trucks making deliveries, noises
from forklifts and roll -up doors at the rear of semi -trailers, noises from hydraulic equipment
(presumably cardboard compactors, lift gates, and forklifts), and some noises from rolling
delivery carts while unloading smaller trucks.
When adjusted for the setback distance of the homes on Arliss and Bacall, the predicted
levels associated with the loading dock will be:
momentary Leg L10 ambient L10
semi -trucks 45-53 28 34 45-53 early am hours
straight trucks 34-39 28 30
loading dock activities 29-36 28 29
These predicted numbers include the considerable barrier effect of the store's southwest
corner and the newly increased distance to homes. The loading dock is now placed where
the 24 foot high store building itself will shield against loading dock noise. An 8 foot high
screen wall around the trash compactor will also act as a very effective and very tall noise
barrier for homes to the west and south. Barrier calculations using this new geometry
indicate attenuation of 10 dBA minimum. Extra distance accounts for another 8 dB of
attenuation.
For comparison, ambient noises include traffic on Chinden and on Linder that created levels
at the nearest Arliss Street homes observed at 47-57 dBA for cars and pickup trucks,
motorcycles were 46-48 dBA, and large trucks were 47-55 dBA from Chinden Road.
Aircraft overflights were 45-52 dBA, and a paramedic unit that passed northbound on Linder
had a siren that measured 70 dBA as it passed by the site at 10:27 pm. The siren was 50-
54 at distance (presumably while approaching major cross streets) and while moving away
northbound past the Chinden / Linder intersection.
For the Rattlesnake Court area, ambient traffic noises were 55-73 dBA for vehicles. The
quietest level observed between 5:30 — 7:00 am was 46 dBA.
For reference, normal conversations across a table are typically about 65 dBA, a raised
voice is 70-80 dBA, the sound level inside a luxury vehicle at freeway speed is 70-75 dBA.
A busy urban street averages 72-74 dBA on the sidewalk, with momentary events of 80-85
dBA from trucks and buses or from motorcycles accelerating away from traffic lights. A dog
bark from across a street is often 70 dBA, and birds chirping in the trees overhead are 45-
60 dBA. The lawnmower in the neighbor's yard is 76 dBA measured at 50 feet.
The L10 levels expected from the loading dock, when adjusted for the distance of the
nearest homes, will be much lower in level than the pre-existing ambient noises (L10) that
the area currently experiences during the early morning hours.
Signs were noted at the existing Winco loading dock prohibiting idling trucks and the use of
engine -driven refrigeration units on trailers not powered by shore power. Engine driven
compressors on board the trailers can create significant constant noise, but refrigeration
equipment is much quieter when powered electrically.
The new design includes a secondary landscape berm / barrier and 8 foot high screen wall
which will shield loading dock noises from homes to the west on Rattlesnake Court.
CONCLUSIONS
• The new site design relocates the Winco store further to the west and will serve to
greatly reduce noise levels at homes from the previously predicted levels. The new
design also places the loading dock farther from homes and uses the store building and
supplemental screen walls as barriers to further reduce noise.
• The October 2017 study also concluded that loading dock and store -related noises for
the old design would not create an adverse impact on nearby homes, and the predicted
levels with the new site design are considerably lower.
• Based on this information, we expect that noises from the loading dock will be lower in
magnitude than the pre-existing ambient sound levels in the area, even during the
quieter nighttime hours. When the new noise is less than (or even comparable to) the
pre-existing noises, that is generally considered to create no adverse noise impact.
• Some louder or distinct sounds from the store such as slow moving semi -trucks may be
intermittently audible and identifiable. This applies to the Arliss / Bacall homes and at
homes west of Linder Road along Rattlesnake Court. The magnitude, number, and
duration of these noises will be well below the frequent pre-existing sounds. There are
numerous delivery trucks, garbage trucks, fire vehicles, and other noises that occur
routinely in the area already.
Let me know if there are any questions about this information.
Sincerely,
Earl Mullins, PE
attached: site maps, 24-hour chart
DEFINITIONS
LeQ (Equivalent Level) is the measure typically used in environmental noise analysis. Since
noise varies over time, an overall descriptor is needed. The Leq is determined by summing
the total sound energy each second, then dividing the total accumulated energy by the total
time. While not mathematically precise, think of Leq as the "average" sound level that
occurred during the measurement, usually a one hour period.
L10 is the sound level that is exceeded 10% of the time, or six minutes out of a given hour.
L10 generally represents the loudest repeating sound levels that occur, such as trucks and
buses versus cars. Loading dock activities are sporadic in nature and limited in duration,
therefore, L10 is an appropriate basis of comparison.
L90 is the opposite of the L10. Noise in the area is louder 90% of the time, or quieter during
only 10% of the hour. L90 is generally considered to be the effective "noise floor" in the
area, since it is only quieter during atypical and unusual moments without any traffic, wind,
aircraft, dog barks, or other local noises.
dBA (A -weighted sound pressure level in decibels)
A -weighting is the standard way to measure sound for judging loudness and annoyance.
Humans hear different frequencies better than others. It takes a much higher level of very
low frequency sound (thunder, bass guitar) to sound equally as loud as a high frequency
sound (cymbals, whistles, turbines, squeals). The "A" weighting filter on the sound meter
applies a correction factor to certain frequencies that correspond to perceived loudness.
Two sources like a diesel railroad locomotive and a cymbal, both measuring 80 dBA, will
sound similarly loud despite the radical difference in frequency content.
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