HomeMy WebLinkAbout20201823.tiffWaveEngineering
May 26, 2020
Mr. J.C. York, P.E.
J&T Consulting, Inc.
305 Denver Avenue, Suite D
Fort Lupton, CO 80621
Acoustics, Noise & Vibration
Re: Bennett Gravel Pit — Sound Monitoring Report
Wave #1979A
Dear J.C.,
Wave Engineering has measured sound levels around the Bennett Gravel Pit. Sound levels were
measured at four locations from Tuesday, May 5, through Friday, May 8, 2020. The intent of the
measurements was to determine the sound levels around the Bennett Gravel Pit property and
compare these sound levels to the Weld County noise limits. The sound levels presented in this
report are ambient sound levels. That is, they include the sound associated with the Bennett
Gravel Pit as well as traffic, aircraft, animals, and other sound sources in the area.
Sound Level Measurements
Sound levels were measured around the Bennett Pit facility from Tuesday, May 5, through
Friday, May 8, 2020. The measurements spanned four days and included two full 24 hour days.
The Bennett Gravel Pit is not yet fully operational but there were two CAT wheel loaders and
one 40 -ton haul truck operating, as well as the on -road semi -trucks loading up and leaving the
site. This was confirmed by Chris Zadel as well as through personal observation on site. The test
equipment, locations, conditions, and results are described below.
Measurement Procedures and Locations
Four sound meters were set up to continuously record a series of 15 -minute duration
measurements. The overall A -weighted equivalent sound level (average) was measured as well
as the minimum, the maximum, and a series of statistical sound levels. Octave band and one-
third octave band data are available if needed. The four locations are shown in Figure 1.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
(±gcnmon iCc'ctlons
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Mr. J.C. York
May 26, 2020
Page 2
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Figure 1: Measurement Locations
Measurement Locations 1 and 2 are within ten feet of the Bennett Pit boundary.
Location 3 was located on the east side of the home at 10808 Co Rd 23, west of the pit. Location
4 was located on the east end of the earth berm, north of the Bennett Pit entrance road.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
Mr. J.C. York
May 26, 2020
Page 3
Test Equipment
The following test equipment was used.
Location 1: Meter M5 (SoundAdvisor)
Larson Davis Model 831C sound level meter S/N 10640, Type 1 per ANSI S1.4
PCB preamp PRM831, S/N 058373
PCB '/2" microphone Model 377B02, S/N 310349
Location 2: Meter M6 (SoundAdvisor)
Larson Davis Model 831C sound level meter S/N 10951, Type 1 per ANSI S1.4
PCB preamp PRM831, S/N 63658
PCB %2" microphone Model 377B02, S/N 315212
Sierra Wireless Airlink RV50 cellular modem
Location 3: Meter M3
Larson Davis Model 831 sound level meter S/N 0004081, Type 1 per ANSI S1.4
PCB preamp PRM831, S/N 036934
PCB '/2" microphone Model 377B02, S/N 153301
Location 4: Meter M2
Larson Davis Model 831 sound level meter S/N 0001119, Type 1 per ANSI S1.4
PCB preamp PRM831, S/N 026106
PCB '/2" microphone Model 377B02, S/N 138652
System calibration was checked in the field before and after the measurements with a Larson
Davis CAL200 acoustic calibrator S/N 11780. Laboratory calibration certificates for the
equipment are available upon request. All of the sound level meters meet the requirements of
ANSI S1.4 Class 1, IEC 60651 Type 1, and IEC 61672 Class 1.
Windscreens and bird spikes were used on all microphones.
Sound Level Limits
Weld County has set the maximum allowable residential property sound level limit at 55 dBA
during daytime hours, and 80 dBA for Industrial areas or Construction Activities during daytime
hours. Daytime hours are between 7:00 am and 9:00 pm. As the Bennett Gravel Pit is only
scheduled to operate during daytime hours, these are the sound level limits we will be comparing
our results against.
We applied the 80 dBA sound level limit to Locations 1, 2, and 4, and the residential 55 dBA
sound level limit to Location 3.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
Mr. J.C. York
May 26, 2020
Page 4
Weather Conditions
Weather and meteorological conditions can influence the transmission of sound outdoors and
have a significant effect when sound travels distances greater than about 300 feet. Wind speed
and direction, and the presence of a temperature lapse or inversion, have the most influence on
sound transmission between distant points. Wind and rain can also have a significant effect on
measured sound levels due to the sound from rustling leaves, grass, rainfall, etc. Sound levels
that are measured when the wind is greater than 8 to 10 mph are more likely affected by the
noise of wind blowing leaves and grass. Wind at these speeds can also affect measurements by
creating noise as it blows across the microphone and windscreen. This can be heard on the audio
recordings when it occurs.
All four measurement locations are susceptible to sound levels that change with wind direction
and other atmospheric conditions. Locations 1 and 2 are the closest to noise producing
equipment and should experience the least variation due to weather. Location 4 is the furthest
from the plant and so we expect the most variation due to wind and weather.
Weather data from Weather Station KCOFORTLI7 was referenced online through the Weather
Underground website (wunderground.com).
The weather conditions for the week are plotted in Figures 2, 3, 4, and 5.
As shown in the figures, there were periods of time during Thursday, May 7th (nighttime) and
Friday, May 8th (morning) where the meters experienced wind speeds near 30 mph. Because of
the high wind speeds, the sound levels measured during this time were heavily impacted by the
wind. Sound levels taken during this time are not valid ambient sound level measurements due to
the high winds.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
Mr. J.C. York
May 26, 2020
Page 5
May 5. 2020
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May 6. 2020
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■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
Mr. J.C. York
May 26, 2020
Page 6
May 7. 2020
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May 8, 2020
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Figure 5: Temperature, Wind Speed/Direction, and Precipitation (May 8th)
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
72O -446 -WAVE (9283)
www.WaveEngineering.US
V
Mr. J.C. York
May 26, 2020
Page 7
Sound Level Measurement Results
Sound levels were measured at four locations over a span of four days that included two full 24 -
hour days. The sound level meter cannot discriminate between sound generated by the Bennett
Gravel Pit, traffic, animals, or other sources such as aircraft. However, we can often use the
recorded audio files to identify the source of spikes or increases in sound levels.
The Equivalent sound level (LAEQ) in dBA and the 90% percentile level (LAS90) in dBA are
plotted in Figures 6 through 10. Each plotted data point is a 15 -minute measurement.
The LAEQ (equivalent sound level) is essentially the average sound level for a given time period.
The time period, or interval, for these measurements is 15 -minutes.
The LAS90 is the sound level that is exceeded 90% of the time. The LAS90 is usually close to the
minimum measured sound level and is used to indicate the steady "residual" sound level without
the influence of passing cars, aircraft overflights, occasional wind gusts, etc. Again, the
measurement duration is 15 -minutes.
At Location 4, traffic was heavy on the Bennett Pit entrance road and this increased the LAS90 as
well as the LAEQ sound levels, except late at night and early in the morning when traffic was
light.
The sound of Bennett Gravel Pit equipment was audible, at least at certain times, at all four
locations. In some locations, the sound from the pit was faint, while in other locations, the sound
was easily noticeable. There were also times when sound from the gravel pit was not audible at
the measurement locations due to passing cars, trucks, wind, etc.
Traffic from nearby roads was audible at all locations and the sound levels varied due to wind
direction and atmospheric conditions.
There were several times when wind affected the measurements and increased sound levels
(when the wind speed was consistently over 10 mph). Those times are noted on Figures 6-10
with a black bar and the data taken during these times are not valid for evaluating noise from the
pit operations.
The orange dashed lines in Figures 8 and 10 mark the 55 dBA limit, and the red dashed lines in
Figures 6, 7, 9, and 10 mark the 80 dBA limit. We attempted to identify the cause of sound level
"spikes". Note that while the sound level did go over 55 dBA at certain times in all locations,
there were no times when the measured sound levels exceeded 80 dBA.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
Mr. J.C. York
May 26, 2020
Page 8
West Property Line (South) - Location 1
Sound Pressure Level (dBA)
90
80
70
60
50
40
30
20
10
0
Frogs, overhead
aircraft, and music
from unknown
source
Bird chirping
near
microphone
Hel
Wind East/NE/SE
icopter
noise
4
Frogs, birds
chirping, and
music from
unknown source
Birds chirping,
and nearby
Truck/Tractor
■
Wind,
frogs, and
birds
chirping
Wind West/NW
Wind North/NE/East
Wind,
frogs, and
birds
chirping
LAeq (dBA)
LAS90 (dBA)
r.,
0
00
O
Tuesday
May 5th
0
O
rn
O
NJ
O
Wednesday
May 6th
00
0
0
O
Thursday
May 7th
x
Friday
May 8th
Figure 6: Sound Levels at Measurement Location 1
Location 1 was northwest of the Bennett Pit near the boundary. Noise due to pit operations was
audible at certain times but was not the dominant noise source. Moreover, there was no clear
dominant noise source as most of the noise sources had a similar dBA level. Other common
ambient noise sources included nearby traffic noise on WCR 23, frogs, horses, birds, aircraft,
and nearby farm equipment.
The LAEQ levels were generally below 55 dBA and were completely below the 80 dBA limit.
We were able to identify the cause of most of the noises that exceeded 55 dBA and they are
indicated by the key notes. The noise of high wind speeds on the night of Thursday, May 7th, and
morning of Friday, May 8th, increased the noise levels.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
N
G
Mr. J.C. York
May 26, 2020
Page 9
West Property Line (North) - Location 2
Sound Pressure Level (dBA)
90
80
70
Bird
60 chirpi
50
30
20
10
U
o
O
Bird landing
near
microphone
A
Tuesday
May 5th
Bird
chirping
rn
0
0
Wind East/NE/SE
Bird chirping,
helicopter noise
I
N
O
O
Wednesday
May 6th
Helicopi
er noise
isa
03
O
O
sot
Figure 7: Sound Levels at Measurement Location 2
Bird
chirping
n
1
12,
C
a
1
■
Wind West/NW
Increased S_
noise due
to wind
r.,
Thursday
May 7th
r
Wind North/NE/East
Bird
chirping
N.
1
Aircraft
noise
LAeq (dBA)
LAS90 (dBA)
rn
J
O
Friday
May 8th
Location 2 was located northwest of the Bennett Pit. Noise due pit operations was audible at this
location at certain times but was not the dominant noise source. Common noise sources included
nearby traffic noise, birds, aircraft, and nearby farm equipment.
The LAEQ levels were generally below 55 dBA and were completely below the 80 dBA limit.
We were able to identify the cause of most of the noises that exceeded 55 dBA and they are
indicated by the key notes. High wind speeds on the night of Thursday, May 7th, and morning of
Friday, May 8th, led to increased noise levels.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
Mr. J.C. York
May 26, 2020
Page 10
Neighbor's House - Location 3
Sound Pressure Level (dBA)
90
80
70
60
50
40
30
20
10
0
N
O
O
Bird
chirping
and
insects
4
Es
p.
00
O
O
Tuesday
May 5th
Mower
Wind East/NE/SE
Bird
chirping
and
helicopter
a
.
O
O
Wednesday
May 6th
A
Increased
noise due
to wind
N
O
O
Thursday
May 7th
Wind West/NW
Tr
O
O
O
O
O
O
JO
O
O
Wind North/NE/East
lf;v1
V''
O
0
LAeq (dBA)
LAS90 ((IBA)
Friday
May 8th
Figure 8: Sound Levels at Measurement Location 3
Location 3 was northwest of the Bennett Pit, on a neighboring property at 10808 Co Rd 23.
Noise due to Bennett Pit work was faintly audible at this location at certain times but was not the
dominant noise source. The loudest noises were from trucks on WCR 23. Other common noise
sources included nearby traffic noise, birds, dogs, aircraft, and equipment from the nearby house.
The LAEQ levels were generally below the 55 dBA residential limit. The limit was exceeded at
times, but none of these occurrences appeared to be due to noise from Bennett Pit work. We
were able to identify the cause of most of the exceedances and they are indicated by the key
notes. The noise of high wind speeds on the night of Thursday, May 7th, and morning of Friday,
May 8th, increased the noise levels.
■
1 100 W. Littleton Blvd. #420
Littleton, CO 80120
72O -446 -WAVE (9283)
www.WaveEngineering.US
Mr. J.C. York
May 26, 2020
Page 11
Northern Earth Berm - Location 4
Sound Pressure Level (dBA)
90
80
70
60
50
40
30
20
10
0
N
O
O
Truc
k
noise
and Bird
chirping
Tuesday
May 5th
0
O
a'
O
O
Wind East/NE/SE
,AAPA
N
O
O
Wednesday
May 6th
Truck
noise
and Bird
chirping
Figure 9: Sound Levels at Measurement Location 4
ick
noise
and Bird
chirping
■
Increased 4
noise due
to wind
NJ
C
Thursday
May 7th
Wind West/NW
Wind North/NE/East
Bird _
chirping
J
rruck
noise
and Bird
p chirping
LAeq (dBA)
LA590 (dBA)
Friday
May 8th
Location 4 was located north of the Bennett Pit, on the east end of the earth berm. Noise from pit
operations was faintly audible at this location at certain times but was not the dominant noise
source. Noise from the trucks passing on the access road was the dominant noise source at this
location. Other common noise sources at this location included frogs, birds, and aircraft.
The LAEQ levels were generally below 55 dBA and were completely below the 80 dBA limit.
We were able to identify the cause of most of the noises that exceeded 55 dBA and they are
indicated by the key notes. The noise of high wind speeds on the night of Thursday, May 7th, and
morning of Friday, May 8th, increased noise levels.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
N
O
O
Mr. J.C. York
May 26, 2020
Page 12
Locations 1- 4
Sound Pressure Level (dBA)
90
80
70
60
50
40
30
20
10
0
9
a
c
S
Tuesday
May 5
Wednesday
May 6
x
U
g
Wind West/NW Wand North/NE/E
I
i
Location 1 - M5
----Location 2 - M6
Location 3 - M3
Location 4 - M2
Thursday
May 7
O
C
ast
Friday
May 8
0
Figure 10: LAEQ Sound Levels at Measurement Locations 1-4
The LAEQ sound levels of all four measurement locations are plotted together for comparison on
Figure 10.
Table 1 below shows the daily average of sound levels for the four test locations. The averages
shown in the table are logarithmic averages. Only days with a full 24 hours of data are shown.
Note that these averages also include the data from the high wind hours.
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
Mr. J.C. York
May 26, 2020
Page 13
Table 1.0 Daily Averages and Location Averages (full days only)
Date
5/6/2020
5/7/2020
Location
Location
Average
1
53
57
56
2
50
56
54
3
47
54
52
4
57
61
59
Conclusions
Sound levels were measured at four locations near the Bennett Pit property from May 5 to May
8, 2020. The sound levels remained consistently below the 55 dBA at the Location 3 residence
and completely below 80 dBA near the Bennett Pit boundary, which meets sound level limits
established by Weld County.
There were short "events" at Location 3 where the 55 dBA limit was exceeded, but these events
did not appear to be due to noise from the gravel pit. We did our best to identify these noise
sources in the charts above. The 80 dBA limit, which applies to Locations 1, 2, and 4, was never
exceeded at any of the measurement locations.
We understand that there have been complaints of back-up beepers at the pit, possibly before
7:00 a.m. We listened to the available audio files between 5:00 a.m. ad 7:00 a.m. and were not
able to hear back-up beepers at any of the measurement locations before 7:00 a.m. We could hear
them at times during the day.
Please let me know if you have any questions or would like to discuss this report.
Sincerely,
Digitally signed by Nathaniel Flanagin
DN: C -US,
.
Nathaniel Flana �• �j nathanielf Eewaveengineenng us.
9 O=Wave Engineenng, CN=Nathaniel
Flanagin
Date 2020.05 26 17 32 41-06'00'
Nathaniel Flanagin
Staff Consultant
■
1100 W. Littleton Blvd. #420
Littleton, CO 80120
720 -446 -WAVE (9283)
www.WaveEngineering.US
Jeff Kwolko
ko
Digitally signed by Jeff
Kwolkoski
DN: C=US,
sk• E=jeffk@waveengineering.us,
i O=Wave Engineering, CN=Jeff
Kwolkoski
Date: 2020.05.26
17:33:54-06'00'
Jeff Kwolkoski, P.E., INCE Bd. Cert.
President
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