HomeMy WebLinkAbout1.01 Noise ReportNoise Analysis
for the proposed
North Hangs Pit
June 28, 2021
Prepared for:
Western Slope Materials
Prepared by:
Hankard Environmental, Inc.
...
Ht:=ONMENTAL
~ -c::::::: -=-:::::.,. ~
ACOUST ICS AND V I BRA TION C ONSULT I NG
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental
June 2021 i
Contents
Executive Summary ................................................................................................................................... ii
1. Introduction ........................................................................................................................................... 1
2. Applicable Noise Standards ................................................................................................................ 2
Time of Day ........................................................................................................................................... 2
Land Use ................................................................................................................................................ 3
Noise Level Compliance Locations .................................................................................................... 4
Construction Noise Limits ................................................................................................................... 4
3. Noise Modeling Methodology ............................................................................................................ 5
Noise Sources ........................................................................................................................................ 5
Noise Receptors and Contours ........................................................................................................... 6
Terrain and Ground Effect .................................................................................................................. 6
Atmospheric Conditions ...................................................................................................................... 7
Noise Barriers ........................................................................................................................................ 7
4. Noise Level Results............................................................................................................................... 8
Noise from Pre-Mining Construction ................................................................................................ 8
Noise from Mining Operations ........................................................................................................... 8
5. Conclusions.......................................................................................................................................... 12
Figures
Figure 1-1. General Location of the Proposed North Hangs Pit ......................................................... 1
Figure 3-1. 3D View of the SoundPLAN Noise Model ........................................................................ 5
Figure 4-1. Predicted Noise Level Contours for the Proposed Operations .................................... 10
Tables
Table 3-1. Source Sound Levels Used in Analyses ............................................................................... 6
Table 4-1. Assessment of Noise Compliance for the Proposed Operations ...................................... 9
Table 4-2. Predicted Worst-Case Noise Levels from Proposed Operations at Residences ........... 11
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental
June 2021 ii
Executive Summary
A noise study was conducted for the North Hangs Pit (Project) to be located near Silt in Garfield
County, Colorado. This Project is proposed to include aggregate mining, aggregate processing,
and a concrete ready-mix plant. The mining is anticipated to last for 15 to 20 years with the
processing facility and concrete ready-mix plant to remain active beyond this timeframe. A total
of three pits will be mined including two smaller ones to the south and one larger one to the north
with operations commencing at the pits in the south before the northern pit. Land use in the area
immediate surrounding the Project consists primarily of vacant land and an existing aggregate
mining operation immediately south. The nearest residence is located approximately 1,600 feet
from any proposed mining operation. Existing noise levels in the area are dominated by traffic
on Interstate 70 and US 6, as well as intermittently from railroad and mining activity.
Noise from this Project is subject to Garfield County’s Land Use Resolution Code, Article 7-1001:
Industrial Use, which references the Colorado Revised Statutes (CRS) §25-12 regarding maximum
permissible noise levels for the surrounding land use zones including residential (55 dBA), light
industrial (70 dBA), and industrial (80 dBA). Sources of noise from the Project include that from
excavators, bulldozers, aggregate crushers and screens, aggregate wash plant, haul trucks, and
operation of a concrete ready-mix plant.
Worst-case (loudest) noise levels were predicted assuming mining would take place in only one
pit at a time. Thus, for each individual pit simultaneous operation of all the equipment was
assumed (e.g., processing area, ready mix plant, mining operations) with the mining equipment
located at the existing surface and not below grade where the terrain can act as a barrier to noise.
It was also assumed all noise berms and aggregate stockpile barriers were already constructed as
recommended. Noise levels were predicted at the compliance locations 25 feet inside the adjacent
parcels, and, while not required for compliance, at the nearest residences (structures) themselves.
The predicted noise levels at the compliance locations are all below the applicable noise level limit
for their land use zone. Additionally, the predicted noise levels at the nearest residential locations
range from 44 to 51 dBA, which are below 55 dBA residential limit.
The Project proposes to construct ten-foot-tall noise berms along the southern boundary and near
the concrete ready-mix plant. The noise analysis indicated the need for a 125-foot-long extension
of the berm on the western property line near the concrete ready-mix plant. It was also found that
the aggregate processing facility should be blocked to the north with twenty-foot-tall aggregate
stockpiles.
Provided that all the recommendations and assumptions as defined herein are followed, noise
from the construction and operation of the proposed Project is predicted to be in compliance with
Garfield County’s Land Use Resolution Code, Article 7-1001: Industrial Use.
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 1
June 2021
1. Introduction
This report describes a noise analysis conducted by Hankard Environmental for the proposed
North Hangs Pit (Project). As shown in Figure 1-1, the 72.8-acre site is located near Silt, Colorado
in Garfield County on the north side of Interstate 70. Immediately north of the site is the Colorado
River and railroad tracks with US 6 to the north of that. Otherwise, the surrounding area is mostly
vacant land with existing gravel mining operations in the general area including one immediately
to the south. The nearest residence is located approximately 1,600 feet from proposed mining
operations. Existing daytime noise sources in the area include traffic on Interstate 70 and US 6, as
well as the railroad and other mining activity.
The proposed operations on the site include the mining of aggregate, processing of aggregate, a
ready-mix concrete batch plant, and the loading of gravel and concrete trucks to deliver the
processed materials off-site. The proposed hours of operation will be Monday through Saturday
from 7:00 am to 7:00 pm for 200 days per year between mid-April to mid-October. The mining
operations are anticipated to last 15 to 20 years with the processing facilities to remain permanent.
The major noise-producing equipment associated with the operation of the Project include
excavators, bulldozers, aggregate crushers and screens, aggregate wash plant, haul trucks, and a
concrete ready-mix plant. The Project will operate using electrical line power versus standalone
generators. The louder aggregate processing will be shielded from the nearest residential areas
to the north using aggregate stockpiles.
Figure 1-1. General Location of the Proposed North Hangs Pit
ProjedAnta
\'--•
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 2
June 2021
2. Applicable Noise Standards
Noise from the operation of the proposed Project is subject to Garfield County’s Land Use
Resolution Code, Article 7-1001: Industrial Use. The County’s code references the Colorado
Revised Statutes (CRS) §25-12 regarding maximum permissible noise levels. CRS §25-12 noise
limits are shown in Table 2-1. The applicable limit depends on the time of day and the zone of
land adjacent to the project. Zones are defined by their land use, which are defined in Section 102
of CRS §25-12. Below provides a summary of each land use zone. Refer to Appendix A for more
detailed information regarding the applicable resolution and statute.
"Residential zone" means an area of single-family or multifamily dwellings where
businesses may or may not operate in such dwellings.
“Commercial zone” is an area where offices, clinics, and the facilities needed to serve them
are located.
“Light industrial and commercial zone” is an area containing: clean and quiet research
laboratories, warehousing, and is free from concentrated industrial activity.
"Industrial zone" means an area in which noise restrictions on industry are necessary to
protect the value of adjacent properties for other economic activity but shall not include
agricultural, horticultural, or floricultural operations.
TABLE 2-1. Maximum Permissible Noise Levels – Colorado Revised Statutes §25-12
Land Use Zone
Maximum Noise Level (dBA)
Daytime (1) (2)
(7:00 am to 7:00 pm) Nighttime (2)
(7:00 pm to 7:00 am)
Residential 55 50
Commercial 60 55
Light Industrial 70 65
Industrial (3) 80 75
(1) During the daytime, noise levels can increase by 10 dBA for 15 minutes in any one-hour period
(2) Noise level limit decreased by 5 dBA for intermittent shrill-type sounds
(3) For construction and development operations, the Industrial limits apply to all zones.
Time of Day
It is our understanding that the proposed processing facility will be constructed and will operate
only during daytime hours, as defined by CRS §25-12 (7:00 am to 7:00 pm.) Therefore, it is only
the Daytime limits shown in Table 2-1 that are applicable, and these limits may increase by 10
dBA for 15 minutes in any one hour. Thus, for example, on residential-zoned land, the daytime
operational noise limit is 55 dBA, but can increase to 65 dBA for up to 15 minutes in any one hour.
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 3
June 2021
Land Use
The strongest determinant of the applicable noise limit is existing adjacent land use. Figure 2-1
provides the parcel owner, existing land use, and land use zone that best applies. Note that in
previous noise studies for Garfield County, agricultural, vacant, and grazing land uses were
designated as “light industrial.” In summary:
The most restrictive limit of 55 dBA is to the north-northwest, where the parcel is largely
vacant land, but does have a residence on the western portion.
The least restrictive limit of 80 dBA applies to the parcels to the east and south where the
Town of Silt has water treatment facilities and Gypsum Ranch is an existing gravel mine.
The remaining parcels are all vacant lands with no known existing uses. As discussed
above, these were assigned a limit of 70 dBA for light industrial.
Interstate 70 does not have an applicable use and thus has no noise limit.
Figure 2-1. Surrounding Zoning and Noise Level Limits
24
-----
----------
1 17908100 194
Aspiri Enterprises LLC
Residential -55 dBA
2 17908 100527
Shidelerosa LLLP
Light Industrial -70 dBA
2 17908100527
Shidelerosa LLLP
Light Industrial -70 dBA
...
217909200106
CO Division of Wildlife
Light Industrial -70 dBA
1 17909200085
Gypsum Ranch Co LLC
Industrial -80 dBA
2 179093007 16
5401 ft
9
-54~;---------co Division o~Wildlife
Light Industrial -70 dBA
2179091000 18
2 179
2 17
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 4
June 2021
Noise Level Compliance Locations
The noise level compliance locations for these noise limits are defined as twenty-five feet outside
the Project’s property line, or twenty-five feet inside a receiver’s property line. The regulations
are not applicable to Interstate 70, therefore the compliance locations for the parcel south of
Interstate 70 is 25 feet inside that receiver’s property line on the south side of Interstate 70.
Construction Noise Limits
During construction, the industrial noise level limit of 80 dBA applies to all receiving land uses.
Construction activities generally include the initial grading of the site, installation of the
processing facilities, construction of roadways, and construction of noise barriers such as berms
and aggregate stockpiles.
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 5
June 2021
3. Noise Modeling Methodology
Noise levels were predicted per International Organization for Standardization (ISO) 9613-2: 1996
– Acoustics – Attenuation of Sound During Propagation Outdoors using the SoundPLAN v8.2
software model. ISO 9613-2:1996 predicts noise levels assuming slight downwind conditions
(wind blowing from source to receptor) with an accepted accuracy of ±3 dB out to 3,280 feet (1,000
meters). A sample view of the acoustical model is provided in Figure 3-1. The following describes
how the ISO method was applied on this Project.
Figure 3-1. 3D View of the SoundPLAN Noise Model
There are several parameters in the ISO 9613-2:1996 method, including the locations of the noise
sources and receivers, noise source level and frequency characteristics, terrain and ground type,
and atmospheric propagation conditions. The ISO method assumes optimal acoustic propagation
in all directions, specifically that a “well-developed, moderate ground-based temperature
inversion” is present or, equivalently, that all receptors are downwind of all noise sources at all
times. The specific ISO 9613-2:1996 settings used in this analysis are described below.
Noise Sources
Table 3-1 lists the A-weighted sound power levels and sound pressure levels at 50 feet away from
the source assuming spherical radiation for all modeled noise sources in the Project. Noise sources
include fixed and mobile equipment across the site. For fixed equipment, there will be an
aggregate processing facility (three screens and two crushers), a concrete ready-mix plant, and a
wash plant. For mobile equipment, this will include three excavator/loaders, two bulldozers, a
water truck, and up to five rock haul trucks. The sound power levels for each piece of equipment
or operation were determined from sound level measurements conducted by Hankard
Environmental. Note that the sound power level is independent of the distance from the source,
ground type, etc. and represents all of the sound energy into one point. Each noise source was
\..
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 6
June 2021
modeled at 10-feet above the ground except the concrete ready-mix plant facility which was
modeled at 20-feet above the ground which was the approximate height of the dominant source
of noise (baghouse blower) determined from previous measurements made by Hankard
Environmental of another ready-mix facility.
Table 3-1. Source Sound Levels Used in Analyses
Noise Source Sound Power Level (dBA)
Sound Pressure Level at 50 feet Away (dBA)
Reference
Excavator Loading Haul Truck 108 73 Measured
Bulldozer 112 77 Measured / Specification(1)
Concrete Ready-Mix Plant – Facility 114 79 Measured
Concrete Ready-Mix Plant - Load Out 113 78 Measured
Haul Trucks 105 70 Measured
Water Truck 108 73 Measured
Excavator Loading Hopper 108 73 Measured
Aggregate Crusher 121 86 Measured
Aggregate Screen 114 79 Measured
Wash Plant 105 70 Measured
(1) Overall level from Caterpillar Specification and frequency spectrum from measured Cat D10
Noise Receptors and Contours
In the SoundPLAN model, receptors (prediction points) were located at the existing residences
and 25 feet outside the property line. Noise contours were also predicted to provide a graphical
representation to help show compliance.
Terrain and Ground Effect
The terrain in the Project area was modeled by importing a digital elevation model from the USGS
and merging with the Project’s planned ten-foot tall berms. The acoustical effect of the ground
can be modeled using ground factors from 1.0 (completely absorptive) to 0.0 (completely
reflective). For this Project we assumed an average ground factor of 0.5 for the entire model with
0.2 used for the mining and processing areas. The worst-case (loudest) predictions will occur
when the initial stripping and overburden removal occurs at the existing elevations while there
are still grasses. Note that the Project proposes to only mine during non-winter (frozen ground)
months.
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 7
June 2021
Atmospheric Conditions
The air temperature, relative humidity, and atmospheric pressure were set to conditions of 10°C,
70%, and 1 atmosphere, respectively. These values represent the lowest amount of atmospheric
absorption of sound available in the ISO 9613-2:1996 method, and result in the highest levels of
sound reaching the receptors.
Noise Barriers
The Project initially proposed to construct ten-foot-tall screening berms along the southern edge
of the property line. Based on this noise analysis, a 125-foot extension of the southwestern berm
along the western property line was added. Additionally, the twenty-foot-tall aggregate
stockpiles were rearranged to more effectively block the noise from the processing facility to the
one residential zoned area to the north. These are described further in the results and conclusions
section of this report.
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 8
June 2021
4. Noise Level Results
Noise levels were estimated for the temporary pre-mining construction and more directly
predicted for the longer duration mining and processing operations. These level were then
compared to the applicable noise level limits at the compliance locations which are 25 feet outside
the property line.
Noise from Pre-Mining Construction
Prior to commencement of mining operations, grading of the processing facility site and concrete
ready-mix site will be conducted and line power will be installed on the site. During this grading
process, ten-foot tall noise berms will be constructed at various locations in the Project site as
shown in Figure 4-1. Upon completion of the grading process, a mobile aggregate processing
facility will be located in a similar position as shown in Figure 4-1 and a concrete ready-mix plant
will be constructed in the far southwest corner of the site. Finally, as is common with aggregate
processing, 20-foot-tall (minimum) aggregate stockpiles will be constructed to act as noise
mitigation for the processing area.
These temporary construction activities are anticipated to last 30 to 60 days. The primary noise
sources associated with berm construction will be an excavator and haul trucks. Construction of
the concrete ready-mix plant will require the use of a crane. Construction noise is limited to 80
dBA during the daytime hours with an allowance of 10 dBA louder for up to 15 minutes in any
one-hour period at a location 25 feet outside the property line. It is anticipated that the equipment
will generally not be closer than 25 feet to the property line which is 50 feet from the compliance
location. Per Table 3-1 the anticipated noise levels from this equipment at 50 feet are
approximately 70 to 77 dBA. In the rare instance that the equipment is close to the property line,
the anticipated noise levels could approach 80 dBA at a location 25 feet outside the property line.
Note that the nearest residence to any berm construction is approximately 1,500 feet away where
noise levels are expected to remain below 45 dBA, which is well below the 80 dBA construction
noise limit.
Noise from Mining Operations
Noise from mining operations is anticipated to be loudest off-site when operations are occurring
at the existing ground level. As mining proceeds below ground the terrain acts as a noise barrier
and off-site noise levels will decrease (e.g., Phase 1). Each of the three pits will be mined one at a
time with operations commencing at the two smaller pits in the south. Noise levels were predicted
from operations at each pit, assuming all of the mining equipment is operating at its loudest level.
More specifically, the operation of the processing area, ready mix plant, and one active mining
area in one of the pits which could include up to two excavator loading haul trucks and two
bulldozers mining aggregate and removing overburden were assumed to be operating
concurrently at peak noise emissions. Other noise sources such as the operation of the water truck,
slow moving haul off trucks and vehicles on and off the site are inconsequential to these other
noise sources. To estimate the worst-case noise levels from activity in the mining area, these
mobile noise sources were moved around the edges of the each of the three pits. Refer to Figure
3-1 for one of the noise model layouts in the larger pit to the north.
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 9
June 2021
In order to assess compliance with the applicable noise limits, noise level predictions were made
at locations 25 feet inside each adjacent parcel. Table 4-1 provides a summary of these predictions
and an assessment of compliance based on the applicable noise limits described in Section 2.
Noise level contours were predicted to provide a graphical representation of the predicted levels
with respect to the adjacent parcels as shown in Figure 4-1. These predictions include the Project’s
initially proposed ten-foot tall screening berms on the southern property line as well as an
additional 125-foot long extension of the southwestern berm along the western property line.
Additionally, the aggregate processing equipment and twenty-foot tall stockpiles should be
similarly arranged in order to mitigate noise to the north as shown in Figures 3-1 and 4-1. Per
Table 4-1, the predicted noise levels are 1 to 24 dBA below the applicable limits and in compliance
with Garfield County’s Land Use Resolution Code, Article 7-1001: Industrial Use which
references the Colorado Revised Statutes (CRS) §25-12.
Table 4-1. Assessment of Noise Compliance for the Proposed Operations
Property Line
Compliance
Location
Predicted Noise
Level (dBA)
Applicable Noise Limit
(dBA)
Minimum
Difference (dBA) In Compliance?
North
(Residential) 50 to 54 55 -1 Yes
Northeast
(Light Industrial) 51 to 62 70 -8 Yes
East
(Industrial) 47 to 56 80 -24 Yes
South
(Industrial) 47 to 62 80 -18 Yes
West
(Light Industrial) 51 to 68 70 -2 Yes
Noise Analysis for the Proposed North Hangs Pit
Hankard Environmental 10
June 2021
Figure 4-1. Predicted Noise Level Contours for the Proposed Operations "' Receptors Parcel Zoning -Stockpile D Residential -Berms -Project Boundary . . D Light Industrial T Aggregate Processing Industrial V Concrete Redi-Mix Plant 25 ft Offset Compliance Line Noise Level Contours Mining and Removal of Overburden = 55 dBA Processing Area = 70 dBA -sodBA
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 11
June 2021
While not required to show compliance with County or State regulations, operational noise levels
were predicted at the nearest residences (structures). The location of each residence identified is
shown in Figure 4-1. The predicted noise levels are shown in Table 4-2. The noise levels at 13 of
the 14 residences are below 50 dBA. Noise levels at one residence is 51 dBA. Generally, daytime
noise levels are limited to 55 dBA at residences in places where they are regulated.
Table 4-2. Predicted Worst-Case Noise Levels from Proposed Operations at Residences
Residential Location Predicted Noise Level (dBA)
R01 49
R02 48
R03 48
R04 47
R05 44
R06 47
R07 47
R08 48
R09 49
R10 44
R11 48
R12 46
R13 46
R14 51
Noise Analysis for the Proposed
North Hangs Pit
Hankard Environmental 12
June 2021
5. Conclusions
Provided that the noise management and mitigation measures recommended below are followed,
noise from the construction and operation of the proposed Project is predicted to be in compliance
with Garfield County’s Land Use Resolution Code, Article 7-1001: Industrial Use which
references the Colorado Revised Statutes (CRS) §25-12 (Noise).
1. Mining activities should take place during daytime hours only (7:00 am to 7:00 pm).
2. Equipment and facility noise emission factors should not exceed those listed in Table 3-1.
3. The Project initially proposed 10-foot-tall terrain screening berms along the southern
property line as well as a corner berm wrapping around onto the western property line for
the concrete ready mix plant. A 125-foot long, ten-foot tall extension along the western
property line is necessary for compliance near the ready mix plant. Refer to Figures 3-1 and
4-1.
4. Aggregate stockpiles and processing equipment should be located in similar orientation as
shown in Figures 3-1 and 4-1 with the stockpiles being maintained at no less than 20 feet
tall. This is necessary for compliance to the northern property line.
5. The use of ambient-controlled broadband back-up alarms is recommended for all
excavating equipment. Backing up by contractor vehicles not outfitted with these types of
alarms should be minimized.
6. Good communication with interested surrounding residents/landowners is recommended,
including providing a telephone number to call for information or to lodge a complaint.
7. No blasting should occur on site.
Western Slope Materials
Response to NTC
Noise Mitigation
Memo on response to Noise Mitigation Factors from Noise Study
1. Mining activities should take place during daytime hours only (7:00 am to 7:00 pm).
[WSM agrees and our hours of operation are 7am to 7pm Monday thru Saturday]
2. Equipment and facility noise emission factors should not exceed those listed in Table 3‐1.
[WSM agrees Equipment and facility noise emission factors will not exceed those listed in
Table 3‐1]
3. The Project initially proposed 10‐foot‐tall terrain screening berms along the southern
property line as well as a corner berm wrapping around onto the western property line for
the concrete ready mix plant. A 125‐foot long, ten‐foot tall extension along the western
property line is necessary for compliance near the ready mix plant. Refer to Figures 3‐1 and
4‐1.
[WSM will complete the screening berms as designed, note that the ready mix plant has been
moved East and will not require the additional berming per the attached memo updating the
noise report.]
4. Aggregate stockpiles and processing equipment should be located in similar orientation as
shown in Figures 3‐1 and 4‐1 with the stockpiles being maintained at no less than 20 feet
tall. This is necessary for compliance to the northern property line.
[WSM plans on maintaining stockpiles no less than 20 feet tall to maintain compliance, this
will be evaluated monthly by our management team during inventory measurement with
drone cameras.]
5. The use of ambient‐controlled broadband back‐up alarms is recommended for all excavating
equipment. Backing up by contractor vehicles not outfitted with these types of
alarms should be minimized.
[WSM already uses ambient‐controlled broadband back‐up alarms on our sites and will
continue to use them on the North Hangs site. WSM will also minimize contractor vehicles
not outfitted with these types of alarms.]
6. Good communication with interested surrounding residents/landowners is recommended,
including providing a telephone number to call for information or to lodge a complaint.
[WSM agrees and will keep lines of communication open with interested surrounding
residents and landowners as well as provide contact information for complaints and/or
comments]
7. No blasting should occur on site.
[No Blasting will occur at this site]
Please contact me at 970‐309‐1515 or tjs@ws‐materials with any further questions.
Prepared By: Travis Stewart
COLORADO • WISCONSIN
phone (303) 666-0617 • www.hankardinc.com • phone (608) 345-1445
February 7, 2022
Western Slope Materials
14682 CO-82
Carbondale, Colorado 81623
Re: Addendum to the Noise Analysis for the Proposed North Hangs Pit
Dear Western Slope Materials,
Hankard Environmental revised the noise analysis for the proposed North Hangs Pit (Project) to
address the relocation of the concrete ready-mix batch plant from the southwest corner of the
property to a more central location. As shown in Figure 1, the batch plant was relocated
approximately 1,000 feet to the northeast to the central processing area. Please refer to our report
Noise Analysis for the Proposed North Hangs Pit, Hankard Environmental, June 28, 2021 for a
description of the methods and results of the noise impact analysis for the Project as then
configured. Other than the relocation of the batch plant all other aspects of the noise analysis
remain the same.
Figure 1 – Relocation of Concrete Batch Plant to Processing Area
Noise emissions from the Project must meet the requirements of Garfield County’s Land Use
Resolution Code, Article 7-1001: Industrial Use, which references the Colorado Revised Statues
(CRS) §25-12 regarding maximum permissible noise levels for surrounding land use zones. Per
CRS §25-12 noise level compliance is assessed 25 feet outside the Project property boundary.
Table 1 lists the predicted noise levels from the original analysis (batch plant in the southwest
HANKARD
ENVIRONMENTAL
~...::::::--~~
ACOUST ICS AND V I BRATION CONS ULT I NG
Addendum to the Noise Analysis for the North Hangs Pit Page 2
February 7, 2022
corner), as well as those predicted for the batch plant’s currently planned location near the
processing area. Per Table 1, the maximum predicted noise levels increase by 0 to 2 dBA due to
the relocation, but levels remain in compliance with applicable limits. The predicted noise levels
for the relocated batch plant are shown as noise level contours in Figure 2. As can be seen, the
predicted noise levels are lower than the limit in each land use zone that surrounds the Project.
TABLE 1 – Predicted Noise Levels Along Property Line and Assessment of Compliance
Property Line (25 ft. Outside)
Predicted Noise Level (dBA) Noise Limit (dBA) In Compliance? Batch Plant in
SW Corner
Batch Plant near
Processing Area
PL - North
Residential 50 to 54 50 to 55 55 Yes
PL - Northeast
Light Industrial 51 to 62 54 to 63 70 Yes
PL - East
Industrial 47 to 56 48 to 58 80 Yes
PL - South
Industrial 47 to 62 48 to 62 80 Yes
PL - West
Light Industrial 51 to 68 51 to 68 70 Yes
Figure 2 also shows the locations of the nearest residences. While not required for compliance,
noise levels were predicted at these locations and those levels are listed in Table 2. The predicted
levels at residences are generally the same for each batch plant location with levels unchanged or
changing by no more than 1 dBA.
TABLE 2 - Predicted Noise Levels at Residences with Different Locations for Batch Plant
Residential Location
Predicted Noise Level (dBA) Change In Noise Level Residential Location
Predicted Noise Level (dBA) Change In Noise Level SW Corner Processing
Area SW Corner Processing
Area
R01 49 49 0 R08 48 48 0
R02 48 48 0 R09 49 49 0
R03 48 48 0 R10 44 44 0
R04 47 47 0 R11 48 48 0
R05 44 45 1 R12 46 46 0
R06 47 48 1 R13 46 46 0
R07 47 48 1 R14 51 51 0
,c::::--c:::::::::._...::::..... =--~--==--
ACOUST ICS AND VIBRATION CONS ULTING
I I
I i
I i
I i
Addendum to the Noise Analysis for the North Hangs Pit Page 3
February 7, 2022
Figure 2 - Predicted Noise Level Contours with the Batch Plant Relocated to the Processing Area Parcel Zoning f'l Receptors D Residential -Stockpile -Project Boundary D Light Industrial r--Berms Noise Level Contours 25 ft Offset Compliance Line = 55 dBA Mining and Removal of Overburden c:=-70 dBA Processing Area -80 dBA [~\ = ~ t!j~ ii ~ ~ > I 0 ;; z ; ; ! z c I ,.., ~·,, ~
Addendum to the Noise Analysis for the North Hangs Pit Page 4
February 7, 2022
In conclusion, noise levels from the operation of the North Hangs Pit with the concrete batch
plant relocated to the central processing area are predicted to be in compliance with Garfield
County’s Land Use Resolution Code.
Please call if you have any questions.
Sincerely,
Jeff Cerjan
Senior Acoustical Consultant
Cc: Mike Hankard, Hankard Environmental
,c::::--c:::::::::::._...:::: =--~--==--
ACOUST ICS AND VIBRATION CONS ULTING