P2542 Kevin Manley - Summary Report for West End Trap Club Noise Monitoring, May 14, 2019 ver 1 esi engineering
May 14, 2019
Mr. Kevin Manley
6238318 1h Street
Canon Falls, MN 55009
Subject: Summary Report for
Trap Club Noise Monitoring
Eagan, Minnesota
Dear Mr. Manley:
We understand that you are planning to develop a residential neighborhood of 10 homes near
the West End Trap Club in Eagan, Minnesota. As shown in Figure 1, the development will be
located approximately 200' south of the club, bounded on the east by Brooklyn Lane and on
the west by S. Robert Trail.
The City of Eagan is concerned about gun noise from the trap club and requested that noise
measurements be performed to confirm the site will met the Shooting Range Protection Act.
ESI performed noise monitoring at the nearest residential property line over a 7-hour period
while the trap club was operating (measurement location shown in Figure 1 below). The
following is a summary of the results.
N
SHOOTING -
s « : AREAS T� �• �/
MEASUREMENT
J LOCATION
3 4
v' 2 fi 7 8 9 10 6
Figure 1 —Aerial view of the West End Trap Club and the Manley residential development.
Structures I Vibration I Noise I Monitoring
ESI Engineering Inc. 7831 Glenroy Road Suite 430, Minneapolis, MN 55439
952.831.4646 1 esi-engineering.com
Mr. Kevin Manley May 14, 2019
Trap Club Noise Monitoring Page 2
Noise Code Requirements
The State of Minnesota passed the Shooting Range Protection Act in May 2005, which is
currently in Minnesota Statues, Chapter 87A Shooting Ranges. The intent of the act is "to
provide shooting ranges with the ability to maintain their operating capacity, if local opposition
to an existing shooting range facility arises." Section 87A.05 Noise Standards describes the
allowable noise levels for the operation of a shooting range. It states that "allowable noise
levels for the operation of a shooting range are the levels determined by replacing the steady
state noise L101 and L502 state standards for each period of time within each noise area's
classification with a single LeQ(h) standard for impulsive noise that is two dBA lower than that of
the L 10 level for steady state noise. The noise level shall be measured outside of the range
property at the location of the receiver's activity according to Minnesota Rules, parts
7030.0010 to 7030.0080...Leq(h) means the energy level that is equivalent to a steady state
level that contains the some amount of sound energy as the time varying sound level for a 60-
minute time period."
Section 87A.04 Mitigation Area describes "a change in use, new development, or construction
of a structure subject to this section may be approved if the person seeking the approval or, at
the discretion of the governing body, the approving authority agrees to provide any mitigation
required to keep the range in compliance with this chapter. The person requesting an approval
subject to this section is responsible for the mitigation if the failure to provide the
documentation or required mitigation is the sole basis for the range being out of compliance
with the shooting range performance standards...With the permission of the range operator,
any mitigation required under this section may be provided on the range property."
To explain what the above language means, we have included references and explanations
below. First, Minnesota Rule 7030: Noise Pollution, prepared by the Minnesota Pollution
Control Agency (MPCA), has requirements for maximum allowable sound levels by receiving
land use evaluated at the point of the nearest receiver. Table 1 shows the Rule 7030 L10 and
L50 noise limits per noise area classification (NAC). NAC 1 is residential and recreational land
use, NAC 2 is commercial, and NAC 3 is industrial.
Table 1 - MPCA Code Requirements
Noise Area Receiver Daytime(7AM - 10PM) Nighttime(10PM-7AM)
Classification Type L10 L50 L10 L50
1 Residential 65 dBA 60 dBA 55 dBA 50 dBA
2 Commercial 70 dBA 65 dBA 70 dBA 65 dBA
3 Industrial 80 dBA 75 dBA 80 dBA 75 dBA
L10 is the sound level that is exceeded 10%of the time during a measurement period.
2 L50 is the sound level that is exceeded 50%of the time during a measurement period.
Mr. Kevin Manley May 14, 2019
Trap Club Noise Monitoring Page 3
The protection act says that instead of using the L10 and L50 from the MPCA rules, the L10
level minus 2 dBA shall be used for the requirement. In the case of this project, the shooting
range is only operating during the daytime hours, which has an MPCA requirement of 65 dBA
at the nearest residential property receiver, which means that the trap club requirement is
63 dBA. Leq(h) is the hourly Leg' level, which shall be used for comparison to the 63 dBA
requirement.
If it is determined that any hourly level during the noise monitoring (while the trap club is in
use) exceeds 63 dBA, mitigation needs to be provided. Mitigation options include physical
barriers (like berms, walls, fences, or buildings to block line of sight and reduce noise) and
increased distance from the noise source.
Outdoor Noise Monitoring Results
The monitoring location was set back approximately 200' from the shooting areas (shown in
Figure 1). This measurement location was chosen due to it having line of sight to 3 of the 4
shooting areas and it is near the northern edge of the residential property line of House 3,
making it a worst-case scenario for gun noise.
The monitoring period started Sunday, April 28th, 2019 at approximately 9 AM and ended on
at approximately 4:30 PM. Figure 2 shows a picture of the monitoring system looking
northeast at the West End Trap Club. The system collected sound data continuously for over
7 hours. One hour from 9 AM to 10 AM was used to determine the ambient (background)
noise level without the trap club, and six hours from 10 AM to 4 PM were used to evaluate the
trap club noise. The sound measurement data is provided in Attachment A.
Traffic noise (from S. Robert Trail to the west) contributed to some of the ambient level.
However, in our opinion, traffic did not significantly affect the levels when the trap club was in
use. There was no precipitation during the monitoring period. Although winds were
moderately high, they did not have a negative impact on the noise levels.
3 Leg is the preferred method to describe sound levels that vary over time,resulting in a single decibel value which takes into
account the total sound energy over the period of time of interest.
Mr. Kevin Manley May 14, 2019
Trap Club Noise Monitoring Page 4
TRAP CLUB '
- SHOOTING AREA C�UBHO. SE
imp
JL-
Now
-,0-�--ta
MONITORING
e
a
i . r
Figure 2— Photo looking northeast showing the monitoring equipment and the trap club.
Table 2 summarizes the hourly Leq(h) measurement results, the noise level requirement, and
the weather data for the monitoring period. The monitoring was performed approximately
200' from the middle of the 4 shooting areas. The loudest hourly level measured (from 10 AM
to 11 AM, the first hour the range was open) represents the worst case level at the nearest
home in the future development, which was an Leq(h) of 70 dBA. This is 7 dBA above the
protection act limit, and therefore mitigation is needed.
Table 2— Hourly Monitoring Levels Compared to Code Limit
Measurement Protection Act
Results,dBA Limit Trap Club Weather Conditions
Date Hour Leq(h) L10-2 dBA Conditions Temp Wind Precip
9:00 AM 53.0 Ambient(no guns) 53°F 17 mph N/A
10:00 AM 70.0 53°F 20 mph N/A
11:00 AM 66.0 53°F 17 mph N/A
Sunday, 12:00 PM 66.0 63.0
April 28,2019 Trap Club In Use 52°F 20 mph N/A
1:00 PM 67.0 51 °F 18 mph N/A
2:00 PM 65.0 50°F 16 mph N/A
3:00 PM 59.0 1 1 50°F 23 mph N/A
Mr. Kevin Manley May 14, 2019
Trap Club Noise Monitoring Page 5
Mitigation Recommendations
In our opinion, the most effective mitigation option at this site is a barrier between the noise
source (guns) and the receivers (location of nearest outdoor residential activity). Trees or
other vegetation are not an option as they do not provide significant attenuation unless it is a
really deep and thick forest.
We understand that the proposed houses will be walk-out style, with either 2 or 3 floors
exposed to the trap club (which includes the basement level). The houses may also have
elevated decks in the future. Because of this, we determined the worst-case residential
outdoor receiver may be someone on their deck while the gun range is open. The next worst-
case receiver would be someone in their backyard. We understand that the shooting areas
are at an elevation of approximately 933', the front of the house lots will be at 960', and since
they are walk-out style, the back of the house lots will be at an elevation of 952', which is 8'
lower than the front of the lot and 19' above the shooting area elevation. Figure 3 illustrates
the site in elevation, with the source, receiver, and important elevations noted.
Calculations were performed to determine the minimum barrier wall height needed to reduce
the loudest measured hourly noise level (70 dBA) to the protection act requirement of 63 dBA,
calculated at the elevated deck location and the backyard location. We assumed a deck
height of 10' and a receiver height of 6' (total of 35' above the shooting area elevation for the
deck receiver, or 25' above the shooting area elevation for the backyard receiver). The
calculations are included at the end of this report in Attachment B.
For a deck receiver, the calculations determined that a barrier wall needs to be constructed
with a height of 16' above the backyard elevation (for a total of 35' above the shooting area
elevation). The elevation of someone on their deck is the main factor for this barrier wall
height. We recognize that a 16' tall fence is not practical. Therefore, if decks are built, they
will need a barrier on the sides of the deck facing the trap club. If a 7' tall barrier is built on
the side(s) of the deck facing the trap club, the calculated noise level of a receiver on the deck
is 60.2 dBA, which meets the noise requirement. This is a reduction of about 12 dB in the
noise level from the range, which includes a safety margin of about 3 dB. This barrier must be
a required condition if future homeowners in this development plan on building a deck on the
back of their house. The barrier needs to be 7' tall when measured from the top of the deck.
For outdoor receivers in the backyards during trap club operating hours, our calculations
determined that the barrier wall along the north property line should have a height of 8'. This
barrier can consist of a berm with a fence or wall along the top of the berm. For instance,
there could be a 2' tall berm along the north property line, and then a 6' wall on top of that.
If an 8' tall barrier (berm and fence) is constructed, we calculate the hourly noise level to be
around 59.4 dBA if measured in the backyard of house 4. This is a reduction of about 13 dB in
the noise level from the range, which includes a safety margin of about 3 dB.
Mr. Kevin Manley May 14, 2019
Trap Club Noise Monitoring Page 6
Person on Future Deck(Assumed Height of 10'Above Backyard),Worst Case Residential
Outdoor Activity Location Due to High Elevation,Deck Barrier Wall Must Block Line of
Sight to Gun Noise&Provide Enough Attenuation to Reduce Noise to 63 dBA
Walk-Out Style House
with Rear Deck Deck Barrier Wall,Minimum Height of 7'Above Deck to
Block Line of Sight to Shooting Areas and Reduce Noise
to Below 63 dBA Requirement on Deck
People in Backyard,Noise Mitigated By Shooting Area
c c Property Line Barrier
ca is Property Line Barrier Wali,Minimum Height of B'to
' ___
Block Line of Sight to Shooting Areas and Reduce
Front of Home Lot • .............. to Below 63 dBA Requirement in Backyards
Elevation 960'
------------------
-------•• o
Back of Home Lot 4 -- ----- ..- .- --.. .n
Elevation 952' r^
Approx.; ----- - -
? ;North
in Measurement -
Location; ;Property Line iia - -- ---__
Shooting Area
Elevation 933' 30'-0" I 190'-0"
20'4" S 200'-0"
Figure 3- Elevation view looking west showing the source, receivers, noise paths, and important elevations.
Mr. Kevin Manley May 14, 2019
Trap Club Noise Monitoring Page 7
For both the deck barrier and the property line barrier, they need to be solid and must be one
continuous barrier, with no holes, gaps or openings. For example, a wood fence with non-
airtight gaps between boards and a gap at the bottom of the fence would not be effective as
noise will leak through all openings.
Some material options for the deck barrier and property line barrier are wood (as long as all
boards are tight and flush with one another; no air gaps), metals (e.g. steel, aluminum,
stainless steel), masonry blocks (CMU), concrete, or stucco finished fence. The minimum
thickness of material used depends on the mass and weight of the material. If wood is used,
the minimum material thickness should be at least 3/4" plywood/OSB, or the equivalent weight
of 2.35 pounds per square foot (psf). Any thinner or lighter, then there will be a noise
transmission issue through the barrier itself and the noise requirement may not be met at the
outdoor receivers.
As mentioned above, the deck barriers should be on the side of the deck facing the trap club.
For houses 4 through 10, this means that the north side of the deck should include a barrier.
For houses 1 through 3, the barrier will need to be on portions of the north and east sides of
the deck, so that the barrier blocks line of sight to the trap club from all locations on the deck.
The property line barrier should run from the west edge of house 2's backyard to the east
edge of house 10's backyard (shown with the red line in Figure 4 below). This length of
barrier will attenuate noise to all backyard receivers in the development, so that the
protection act requirement is met at each house.
r N
BARRIER WALL
LOCATION -
3 4
5
Z 5 7 S 9 10
1
Figure 4-Aerial view showing the location of the recommended barrier wall.
Mr. Kevin Manley May 14, 2019
Trap Club Noise Monitoring Page 8
Conclusions
ESI was asked by you to perform noise monitoring at the proposed residential development
site south of the West End Trap Club in Eagan, Minnesota. The City of Eagan has requested
that noise levels be measured to determine if the Shooting Range Protection Act requirements
will be exceeded if the new development is constructed.
At a distance of approximately 200' from the shooting areas, the measurement results
showed that outdoor trap club noise levels exceeded the Shooting Range Protection Act
requirement of 63 dBA a majority of the time the club was operating on Sunday, April 28t",
2019. The loudest hour was the 10 AM hour, which had an hourly Leq of 70 dBA, which was
7 dBA above the requirement.
We recommend that a 7' tall barrier be built on the trap club sides of elevated decks, so that
the barrier blocks line of sight to the trap club from all locations on the deck. This barrier
must have no air gaps, holes, or openings. We expect this barrier to reduce the hourly level
by approximately 12 dB, which will reduce the trap club noise below the state requirement of
63 dBA.
We also recommend that an 8' tall barrier wall be constructed along the northern edge of the
residential development property line. This barrier can be a combination of a berm and an
uninterrupted wall, with no air gaps, holes, or openings. We expect this barrier to reduce the
hourly level by approximately 13 dB if measured in the backyards, which will also reduce the
trap club noise below the state requirement of 63 dBA.
We appreciate the opportunity to work with you on this project and remain available to assist
in the resolution of these and any other matters. Please let us know if you have any questions
or need more information.
Sincerely,
A� 7 Vb,J,
Andrew A.J. Schmitt Anthony J. Baxter, P.E.
Consulting Engineer Principal
ESI Engineering, Inc. ESI Engineering, Inc.
Attachments
File: P2542 Kevin Manley-Summary Report for West End Trap Club Noise Monitoring, May 14, 2019 ver 1
Attachment A
7-Hour Outdoor Noise Monitoring Data
Trap Club Noise Monitoring - May 14, 2019
ill I) esi engineering Acoustic Test Results
Minneapolis,Minnesota I o:952.831.4646 1 esi-engineering.com
Project No: P2542 Analyzer: Larson Davis 831 s/n 3553
Project: Kevin Manley-Gun Club Noise Preamplifier: Larson Davis PRM831 s/n 029391
Location: Eagan, Minnesota Microphone: Larson Davis 3771320 s/n 137686
Engineer: A.A.J. Schmitt Calibrator: Bruel & Kjaer 4231 s/n 3009047
Last Calibrated: February 19, 2019
Location: Site 3 Edge of Backyard Meteorology: Temperature: 49-54°F
Date: 4/28/2019 Wind Speed/Dir.: 12-23 MPH/SSE
Start Time: 8:52:21 AM Humidity: 28-35%
End Time: 4:26:52 PM Calibration Check: Calibration Frequency: 1 kHz
Run Time: 27271.0 seconds Initial Calibration: 93.9 dB
Final Calibration: 93.9 dB
Measurements: One Second and Hourly Ambient Noise Levels Last Cal. Check: 4/28/19 @ 4:28 PM
A-Weighted Results-Sunday,April 28th,2019
Monitor.001-LAF
Monitor.001-Leq
10
4:26:52 PM
dg 46.8 dBA
60.8 dBA
9
9
8
8
m
Zx
0
N
PTO
7
J 6
m co 60
a
a
c
0 5 I
50
45-
40-
35--
30-
9:00:00
4339:00:00 AM 10:00:00 AM 11:00:00 AM 12:00:00 PM 1:00:00 PM 2:00:00 PM 3:00:00 PM 4:00:00 PM
Time,h.m.s AM/PM
Noise Monitoring
Measured Hourly Leq Data
Time Leg Time Le
9:00:00 AM 53 dBA 1:00:00 PM 67 dBA
10:00:00 AM 70 dBA 2:00:00 PM 65 dBA
11:00:00 AM 66 dBA 3:00:00 PM 59 dBA
12:00:00 PM 66 dBA 4:00:00 PM 61 dBA
Figure Al
Attachment B
Noise Barrier Calculations
Trap Club Noise Monitoring - May 14, 2019
Client: Kevin Manley May 9, 2019
esi engineering Project: Gun Club Noise Control Prepared By:AAJS
Project No.: P2542 Checked By: AJB
Barrier Affect Calculation
References:
1. Architectural Acoustics: Principles and Design,
Madan Mehta, James Johnson and Jorge Rocafort, Prentice Hall, 1998
2. Acoustics
Leo L. Beranek, McGraw-Hill Book Company, 1954
3. Sound and Vibration Design and Analysis,
National Environmental Balancing Bureau (NEBB), 1994
4. Noise Control: From Concept to Application,
Colin Hansen, Taylor & Francis, 2005
5. Handbook of HVAC Applications,
American Society of Heating, Refrigeration and Air-Conditioning Engineers, 2011
Noise Control Constants:
dBA Scale Corrections Octave Bands Used Wavelengths
—26.2 1 63 17
—16.1 2 125 9
—8.2 3 250 4
dBA:_ —3.2 OctBnd:= 4 f.— 500 A _ 1 100 ft A— 2 ft
0 5 1000 f 1
1.2 6 2000 1
1.0 7 4000 0
—1.1 8 8000 J 0
Octave Band Sound-Pressure Levels Defining Noise Criterion (NC) Curves
47 51 54 57 60 64 67 71 74 77 80 83
36 40 44 48 52 56 60 64 67 71 75 79
29 33 37 41 45 50 54 58 62 67 71 75
NC:= 22 26 31 35 40 45 49 54 58 63 68 73
17 22 27 31 36 41 45 51 56 61 66 71
14 19 24 29 34 39 44 49 54 59 64 69
12 17 22 28 33 38 43 48 53 58 63 68
11 16 21 27 32 37 42 47 52 57 62 67
Specific NC-Levels
NC15 :=NC NC20 :=NC NC25 :=NC NC3 p :=NC NC35 :=NC NC4 p :=NC
i i,1 1 i,2 1 i,3 1 i,4 i i,5 1 i,6
NC45 :=NC NC5 p :=NC NC55 :=NC NC60 :=NC NC65 :=NC NC7 p :=NC
i i,7 1 i,8 1 i,9 1 i,10 i i,11 1 i,12
Page B - 1
Client: Kevin Manley May 9, 2019
esi engineering Project: Gun Club Noise Control Prepared By:AAJS
Project No.: P2542 Checked By: AJB
Loudest Hour Sound Data:
Leq 1/1 Octave Data: Safety Factor : SF:=2.9
60.6 37
63.8 Check dBA Level : 51
63.8 59 Lp.Leq dBA
s
LpLeq:= 61.4 +SF LpLeq.dBA:=Lp.Leq+dBA= 61 LdBA.Leq:=10•log 10 'o
64.8 68 =1
65.6 70
60.0 64 LdBA.Leq=73.0 dBA
-------------
51.0 53
20' distance correction. Measurement was taken approximately 200 ft from middle of 4
shooting pads. Northern edges of residential property lines are all approximately 200 ft from
each shooting pad, but a person on a deck is set back approximately 20':
Q:=2 d:=200 ft
107
110
1 10 L`",LeQ,+dBA
l s
Lw.Leq:=Lp.Leq+20•log l fJ-10•log(Q)+0.7= 108 LwA.a:=10•log 1: 10 10
l
112 L 117 dBA
107 wA.a=
-----------
98
r:=220 ft Q:=4 for instance of
house reflections
66 39
69 53
r l 69 61
Lp.Deck°=Lw.Leq—20•lOgI I+lo.log (Q)—0.7= 660
Lp Deck.deA:=Lp.Deck+dBA= 70
l f 71 72
65 66
56 55
Lp.Deck.d3A
8
LdBA.Deck:=10•log �7 10 10
i-1
LdBA.Deck=75.2 dBA
Page B - 2
Client: Kevin Manley May 9, 2019
esi engineering Project: Gun Club Noise Control Prepared By:AAJS
Project No.: P2542 Checked By: AJB
Barrier Wall Attenuation -Gun Club Noise to Residential Outdoor Receiver(Person on Deck,
House 3 or 4, no deck barrier/screen):
Sound A k Q
source
0 Reaelver
he �?r
Figure 7.3 Geometry of Sound Propagation Path over
or around a Barrier
a:=190 ft distance between source and
barrier
hs:=6 ft height of source above
ground
b:=30-ft distance between receiver and barrier hby:=19•ft height of backyard
above shooting area
hr:=hby+16 ft=35( fthr—hs/llheight of receiver above ground
\
hb:=a•tan�tanh +hs hb=31.0 ft minimum barrier height to cut off line of sight
H:=35•ft H=35 ft barrier height
A:— a2 +(H—hs` z A=192 ft built barrier height
/) Hb:=H—hby=16 ft
z
8:= b2 +(H—hr) 8=30 ft
D:=V(a+b�+ (hr—h,� distance between source and receiver D=222 ft
r A+B—D —(A+B—D)l
S:=if H>hb, JI difference between the defracted path and the direct path
ft ft
S=0.3
N:= 2•5•ft Fressnel Number NT=�O 0 0 0 1 1 2 4�
A
2•�r•N
IL :=if N <-0.2,0,20•log +5 ILT=[6 6 7 9 11 13 16 19] 6
tanh( �7r
l 6
J 7
Ab :=if rIL >24,24,IL 1 Ab= 9
l J 11
13
16
19
Page B - 3
Client: Kevin Manley May 9, 2019
esi engineering Project: Gun Club Noise Control Prepared By:AAJS
Project No.: P2542 Checked By: AJB
Calculated Sound Level After Barrier Wall Attenuation:
34
47
54 Lp.D-k-t
Lp.Deck.mit'_Lp.Deck.dBA—Ab= 55 $ 10
59 LdBA.mit:=10•log 10
58 -1
50 LdBA.mit=63.4 dBA
36
This meets the Shooting Range
Protection Act Leq(h) requirement of
63 dBA, but includes a safety factor of
—3 dB for house reflections or
increased shooters/gun shots.
LdBA.mit'=LdBA.mit—SF
LdBA.mit=60.5 dBA
-------------
Without the safety factor, this is below the
Shooting Range Protection Act Leq(h)
requirement of 63 dBA.
Page B - 4
Client: Kevin Manley May 9, 2019
esi engineering Project: Gun Club Noise Control Prepared By:AAJS
Project No.: P2542 Checked By: AJB
Barrier Wall Attenuation -Gun Club Noise to Residential Outdoor Receiver(Person on Deck,
House 3 or 4,with deck barrier/screen on sides facing trap club):
Sound A H g
Source
D Reaalver
h$ hr
h ----� -�
Figure 7.3 Georn0y of Sound Propagation Path over
or around a Barrier
a:=219 ft distance between source and
barrier
hs:=6 ft height of source above
ground
b:=3•ft distance between receiver and barrier hby:=19•ft height of backyard
above shooting area
hr:=hby+16 a �tanh
(hr—hs/llft=35 ft height of receiver above ground
\
hb:=
•tan +hs hb=34.6 ft minimum barrier height to cut off line of sight
H:=36•ft H=36 ft barrier height
A:= az +(H—hs` z A-221 ft built barrier height
/) Hb:=H—hby-10 ft=7 ft
z
8:= b2 +�H—hr� 8=3 ft
D:=V(a+b�+ (hr—hs� distance between source and receiver D=224 ft
r A+B—D —(A+B—D)l
S:=if H>hb, JI difference between the defracted path and the direct path
ft ft
6=0.32
N.— 2-5-ftT [— Number Nr=�O 0 0 0 1 1 2 5�
A
2•�r•N
IL :=if N <-0.2,0,20•log +5 ILT=[6 6 7 9 11 14 17 20] 6
tanh( �7r
l 6
J 7
Ab :=if(IL >24,24,IL 1 Ab= 9
l — J 11
14
17
20
Page B - 5
Client: Kevin Manley May 9, 2019
esi engineering Project: Gun Club Noise Control Prepared By:AAJS
Project No.: P2542 Checked By: AJB
Calculated Sound Level After Barrier Wall Attenuation:
34
47
53 Lp.Deck—t
Lp.Deck.mit'_Lp.Deck.dBA—Ab54 $= 10
59 LdBA.mit'=10.109 10
58 -1
49 LdBA.mit=63.1 dBA
35 _____________
This meets the Shooting Range
Protection Act Leq(h) requirement of
63 dBA, but includes a safety factor of
—3 dB for house reflections or
increased shooters/gun shots.
LdBA.mit'=LdBA.mit—SF
LdBA.mit=60.2 dBA
-------------
Without the safety factor, this is below the
Shooting Range Protection Act Leq(h)
requirement of 63 dBA.
Page B - 6
Client: Kevin Manley May 9, 2019
esi engineering Project: Gun Club Noise Control Prepared By:AAJS
Project No.: P2542 Checked By: AJB
Barrier Wall Attenuation-Gun Club Noise to Residential Outdoor Receiver(Person in Backyard,
House 3 or 4,shorter barrier wall):
Sound A H g
Source
D Reaalver
h$ hr
h ----� -�
Figure 7.3 Georn0y of Sound Propagation Path over
or around a Barrier
a:=190 ft distance between source and
barrier
hs:=6 ft height of source above
ground
b:=30-ft distance between receiver and barrier hby:=19•ft height of backyard
above shooting area
hr:=hby+6 ft=25((fthr—hs/llheight of receiver above ground
\
hb:=a•tan�tanh +hs hb=22.4 ft minimum barrier height to cut off line of sight
H:=27•ft H=27 ft barrier height
z built barrier height
A:=V��+(H—hs� A=191 ft g
Hb:=H—hby=8 ft
z
8:= b2 +(H—hr) 8=30 ft
D:=r(a+bF+(hr—hs� distance between source and receiver D=221 ft
r A+B—D —�A+B—D)_l
b:=ifl`H>hb, JI difference between the defracted path and the direct path
ft ft
S=0.4
N:= 2-5-ftT [— Number Nr=�O 0 0 0 1 1 3 6�
A
2•�r•N
IL :=if N <-0.2,0,20•log +5 ILT=[6 6 8 9 12 15 18 21 6
tanh( �7r
l 6
J 8
Ab :=if rIL >24,24,IL 1 Ab=
9
l J 12
15
18
21
Page B - 7
Client: Kevin Manley May 9, 2019
esi engineering Project: Gun Club Noise Control Prepared By:AAJS
Project No.: P2542 Checked By: AJB
Calculated Sound Level After Barrier Wall Attenuation:
34
46
53 Lp.Deck—t
Lp.Deck.mit'_Lp.Deck.dBA—Ab54 $= 10
58 LdBA.mit'=10.109 10
57 -1
48 LdBA.mit=62.3 dBA
34 _____________
This meets the Shooting Range
Protection Act Leq(h) requirement of
63 dBA, but includes a safety factor of
—3 dB for house reflections or
increased shooters/gun shots.
LdBA.mit'=LdBA.mit—SF
LdBA.mit=59.4 dBA
-------------
Without the safety factor, this is below the
Shooting Range Protection Act Leq(h)
requirement of 63 dBA.
Page B - 8