HomeMy WebLinkAbout1.04 Supplemental Application Materials 12.08.2022
December 9, 2022
Glenn Hartmann
Principal Planner
Garfield County Community Development Department
ghartmann@garfield-county.com
RE: Responses to the Garfield County
Glenn:
SGM has prepared the following responses to the September 28, 2022, Staff Recommendations included
in Section VII, specifically Items #1, #3a-#3c, and #9.
Item #1 - Prior to the issuance of the Land Use Change Permit the Applicant shall revise the site
plan as follows:
a. Revise site plans to show the standard 35 ft. waterbody setback from all wetland areas.
b. Revise site plan to show the standard 100 ft. industrial Use setback from all property lines.
c. Revise site plan to include additional details on internal vehicle circulation and the office,
water and wastewater facilities.
d. Revise site plan to show electric utility connection for the site.
Attachment A provides a revised sheet that depicts the 35-foot setback from the delineated wetland
boundaries and 100-foot setback from the property line. IHC-Scott, will include a revised site plan with
Items #1c and #1d upon approval of this revised berm detail (wetland and industrial setbacks).
Item #3 – Prior to the consideration of the Application by the board of County Commissioners the
Applicant shall:
a. Updated the Environment Study to include consultation with the U.S. Fish and Wildlife on
endangered aquatic and vegetative species and protection of aquatic resources from no n-
native species. See Attachment B.
b. Provide additional documentation on the screening effectiveness of the perimeter berm.
See Attachment C.
c. The Applicant shall provide an updated noise model/assessment to demonstrate
compliance with the noise standards contained in the Table 7-1002 of the Land Use and
Development code including any mitigation required to maintain compliance. See
Attachment D.
Item #9 – Prior to operation of the facility, the subject parcel shall be assigned an address as
approved by Colorado River Fire Rescue and Garfield County. The assigned address for the Rifle
Pit Property is (Garfield County, Mr. Matt Provost): 5127 North County Road 346, Rifle, Colorado
81650
www.sgm -inc.com
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We appreciate your help with this application. Please contact me at angief@sgm-inc.com or 970-384-
9027 if you have any additional questions.
Sincerely,
Angie Fowler, PE
SGM Water and Environmental Sector Leader
Project Manager
cc: Chris Hurley, IHC Scott, Inc.
Tony Roberts, IHC Scott, Inc.
Alex Nees, SGM
Attachment A – Revised Plan Sheet with Berm Detail
Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By:
Project Milestone:Of :2019-341.002RPFRPFRiflePit-ExhibitsABF8118 West Sixth Street, Suite 200
Glenwood Springs, CO 81601
970.945.1004
www.sgm-inc.com Graphic ScaleIn U.S. Feet : 1" = 200'0100200400IHC Scott, Inc. 13Permit Set (Not For Construction)Mining ProgressionExhibit - 100%Rifle Pit Gravel Pit #110/25/2022
Attachment B – U.S. Fish and Wildlife Documentation
GLENWOOD SPRINGS 118 West Sixth St, Suite 200 | Glenwood Springs, CO 81601 | 970.945.1004
IHC Scott’s Rifle Pit #1 – Informal USFWS Consultation
TO: Glenn Hartmann, Principal Planner
Planning Division – Community Development
Garfield County
FROM: Alexander Nees
Senior Ecologist
DATE: December 1, 2022
SUBJECT: NTC Item 3a: Documentation of informal consultation with USFWS regarding
impacts to Endangered Colorado River fish associated with gravel pit construction
Dear Glenn:
I have completed consultation with the U.S. Fish and Wildlife Service (USFWS) regarding any concerns
that the USFWS may have regarding the construction of the Rifle Pit #1 in proximity to occupied habitat
for federally-listed species protected under the Endangered Species Act (ESA). I completed this
consultation in response to the Staff Recommendations developed following the Planning Commission
meeting of September 28, 2022.
As your office is aware, the project does not have a federal nexus (e.g. a federally-issued permit or other
federal regulatory authority). Therefore the consultation was undertaken on an informal basis, rather
than through a formal ESA Section 7 or Section 10 consultation process. Project descriptions and maps
were provided to the USFWS Ecological Services office in Grand Junction, Colorado, along with a
request for their assessment of the project’s potential to impact ESA-listed species, and management
recommendations if any.
I corresponded directly with Kurt Broderdorp – USFWS, who also consulted with other staff in the office.
Email communication and project descriptions were provided on October 25 and 31. Consultation
occurred on November 7, resulting in a preliminary determination of “no concerns”, and final
confirmation of “No concerns or additional management recommendations” was provided on November
21.
In summary: Although IHC Scott has no intention of managing the gravel pond as a recreational facility
or allowing sportfishing, concerns had been expressed that sport fish (particularly smallmouth bass and
tiger muskie) might be introduced accidentally into the gravel pit pond, establish a permanent
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reproductive population in the pond, and then disperse downstream into occupied habitat for ESA-listed
species in the Colorado River mainstem. I requested any recommendations that Kurt – USFWS might
offer with regard to protective measures needed to mitigate the potential for this to occur. Kurt and
USFWS staff had only two suggestions:
1. A request that no direct surface connection be allowed between the pond and downstream
waters. As you know, this is already a key component of IHC Scott’s design, and has also been
requested by CPW. Therefore this recommendation is fully incorporated into the existing
proposal.
2. A request that some type of perimeter berm be maintained around the portion of pond that is
located in the Colorado River floodplain, so that relatively-common flood events (e.g. a 10-yr
event) would not inundate the pond and flush fish into the river. As you know, there is a
perimeter berm already proposed which meets this need, in addition to multiple permit
requirements for screening and floodplain operation associated with your department’s
development permit and the DRMS mine operation permit. The perimeter berm includes not only
the portion of the operation in the floodplain, but the entire perimeter of the mine area. Therefore
this recommendation is fully incorporated into the existing proposal.
Kurt and USFWS confirmed that, with the incorporation of these design features, they had no further
comment on the proposal.
Thank you for your attention in this matter.
Sincerely,
Alex Nees
Senior Ecologist & Team Leader
Attachment C – Visual Screening Documentation
December 9, 2022
Glenn Hartmann
Principal Planner
Garfield County Community Development Department
ghartmann@garfield-county.com
RE: Responses to the Garfield County Staff Recommendation #3b – Visual Screening
Glenn:
Item #3b in the September 28, 2022, Staff Memo to the Garfield County Planning Commission requests
the following:
Prior to the consideration of the Application by the board of County Commissioners the Applicant shall:
b. Provide additional documentation on the screening effectiveness of the perimeter
berm.
This memorandum provides a few conceptual schematics of the proposed Rifle Pit property with a berm
height of 5 feet (Figure 1) from four Viewpoints (Figure 2) during the 30% (Figure 3 through Figure 7) and
100% mined conditions (Figure 8 through Figure 12). Figure 13 depicts typical specifications for the
largest modeled piece of equipment.
These images were generated using InfraWorks, a 3D model which integrates the publicly available
Oracle (GIS) databases. These GIS databases are based on the CO83 Survey Datum (Contour and
Elevation information can have a 5 foot +/- difference from true surface elevations). The ground imagery
is provided using Bing Mapping.
Figure 1. Revised Berm Detail Reflecting 35-foot and 100-foot setbacks for Wetlands and Industrial Uses, respectively.
Figure 2. Overall Site Perspective with Viewpoints #1 through #4.
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Figure 3. Overview of Rifle Pit for the 30% Mined Condition.
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Figure 4. View Looking North from near Viewpoint #1 for the 30% Mined Condition
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Figure 5. View Looking West from Viewpoint #2 for the 30% Mined Condition
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Figure 6. Looking West from Viewpoint #3 for the 30% Mined Condition
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Figure 7. Looking West from Viewpoint #4 for the 30% Mined Condition
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Figure 8. Overview of Rifle Pit for the 100% Mined Condition.
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Figure 9. View Looking North from near Viewpoint #1 for the 100% Mined Condition.
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Figure 10. View Looking West from Viewpoint #2 for the 100% Mined Condition.
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Figure 11. Looking West from Viewpoint #3 for the 100% Mined Condition.
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Figure 12. View Looking Northeast from Viewpoint #4 for the 100% Mined Condition.
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Figure 13. Vehicle Specifications used for the Visual Concepts (Large Speclog for 374D L CAT Hydraulic Excavator, HEHH4376-
02 (EAME), found here: https://s7d2.scene7.com/is/content/Caterpillar/C633458).
Attachment D – Noise Modeling Documentation
GLENWOOD SPRINGS 118 West Sixth St, Suite 200 | Glenwood Springs, CO 81601 | 970.945.1004
IHC Scott’s Rifle Pit #1 – Noise Standard Compliance
TO: Glenn Hartmann, Principal Planner
Planning Division – Community Development
Garfield County
FROM: Alexander Nees
Senior Ecologist
DATE: December 1, 2022
SUBJECT: NTC Item 3c: Documentation of compliance with LUDC noise standards for gravel
operations
Dear Glenn:
SGM has completed additional noise modeling to determine compliance with the noise standards
contained in Table 7-1002 of the Land Use and Development Code (LUDC). This additional modeling
was completed in response to the Staff Recommendations developed following the Planning
Commission meeting of September 28, 2022. It is meant to replace, rather than supplement, the noise
assessment that was reviewed in that meeting (Land Use Permit Application, May 9, 2022 [Revised
August 2022], Section 2.12.3).
The Rifle Pit #1 operation is surrounded by residential uses, and Table 7-1002 establishes an A-
weighted decibel threshold of 55 dB(A) as the maximum allowable daytime noise impact, measured at
25 feet beyond the subject property. IHC Scott is not proposing nighttime operations, so only daytime
standards are addressed here.
In summary, our analysis indicates that the proposed gravel extraction operation would be conducted in
such a manner that the volume of sound generated would not constitute a public nuisance or hazard,
and in compliance with the threshold standards in Table 7-1002.
• The stationary location of the gravel processing (see Sound Propagation Map, attachment A) has
been moved to a location approximately 750 feet from the nearest adjacent property.
• The noise generated by the processing equipment has been measured at 94.3 dB under real-
world operating conditions (see field-collected noise data, attachment B).
• Calculations for the attenuation of sound propagation in the outdoor setting (using ISO 9613
standards) indicate that distance attenuation alone is sufficient to ensure that the sound levels at
adjacent properties are well below the 55 dB(A) threshold requirement.
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• Perimeter berms, surface absorption, screening vegetation, and existing background noise would
further reduce the effective apparent noise impact to adjacent properties, but are not modeled in
detail here since they are not necessary to show compliance with the standards in Table 7-1002.
Design Alterations
Since the original noise assessment was provided to your office, several substantive design changes
have been made to the proposal that drastically alter the noise considerations, and that necessitate a
new noise assessment as provided in this memo. These changes are generally driven by the transition
from the originally-proposed dry-mining design to the current proposal for wet mining, and include the
specific relevant issues:
• The crushing operation has been moved to the south side of the property, and will be stationary
throughout the mine’s operation phase. Unlike a standard dewatered pit operation, the wet
mining process does not allow for mobile processing equipment, since excavated areas are
allowed to fill with water immediately. Therefore the stationary noise generator location needs to
be modeled at the appropriate specific location (see Sound Propagation Map, attachment A).
• The processing operation will take place essentially at grade, rather than within the excavated
pit, again due to the requirements of the wet mining process. Therefore, the noise levels are not
attenuated due to a below-grade location as is typical in a standard dewatered gravel operation.
• IHC Scott has slightly changed the processing equipment, including a newer, quieter crusher
than was originally proposed. The anticipated noise production can also be further refined
through comparison to substantially-similar, currently operating gravel mines (see Data
Collection below).
Data Collection
To generate the most realistic estimate for anticipated noise production levels at the Rifle Pit #1, IHC
Scott measured the actual noise produced at their currently-operating nearby gravel operation, located
on leased property at 6533 346 County Road, Silt, CO 81652. This gravel operation uses a suite of
equipment that is substantially-similar to that proposed for the Rifle Pit #1, including crusher, processor,
and trailer-contained generating equipment. The noise readings were collected along six transects, all
centered on the center of operations (see attachment B). The highest reading collected was 94.3 dB,
which was used for the point source model described below. Note that the data collection was
performed at typical dewatered pit site, where the processing equipment is located below grade. Sound
reflection off the sides of the pit are likely to amplify noise standards above what would be expected in
an at-grade operation such as Rifle Pit #1. The noise levels collected at the 346 County Road site are
therefore likely to be a slight over-estimate of noise production at the Rifle Pit #1 site.
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Modeling Approach
The sound modeling was completed with the use of 3D computer sound modeling software. All models
in this report were performed with the dBmap.net noise mapping tool1, using the ISO 9613 standard for
outdoor sound propagation.
• A single 94.3 dB point noise source was placed at the location of the processing facility on the
Rifle Pit #1 property.
• Linear distances to the receiver points for the adjacent properties were calculated in a GIS and
imported into the model. Receiver points were located at the closest possible point to the noise
source that was 25 feet within the subject property.
• The software calculated noise attenuation due to distance and provided anticipated noise impact
levels for each adjacent property as follows:
o Colorado River Ranch (North side): 35.8 dB
o Shidelerosa (East side): 39.5 dB
o Ward (South side): 41.5 dB
o Nicola (South side): 40.65 dB
o Robinson (West side): 39.7 dB
Sound levels at the specified receiver points are predicted solely based on the location of the
sound source (the processing facility) and the linear distance to the specified receiver points. The
topography and reflective properties of the local terrain, buildings and barriers, and existing noise
levels are not included in the analysis. The predicted sound levels only take into consideration
the sound produced by the processing facility and do not account for other sources, such as
traffic, other human activity, or environmental factors. No discussion is provided regarding the
relative prominence of the facility noise within the existing soundscape, although previously-
collected data indicate a relatively high level of existing noise, associated predominantly with
traffic on Interstate 70 at the south boundary of the project.
Modeling Approach, Assumptions, & Limitations
The modeling used the following assumptions, all of which are conservative estimates that would
generally increase the estimated noise impacts. The reported dB levels therefore generally
represent a worst case scenario for noise levels apparent at the adjacent properties.
• No topography or screening berms were included. A perimeter berm will be part of the
site as mandated by regulation, but is not necessary to achieve noise compliance.
• The absorption of sound due to vegetation or soft ground surface is not included: the
model uses the assumption of a perfectly-reflective and flat ground surface, which
dramatically increases the propagation of noise produced at the site.
• No allowance is made for the impact of Interstate 70’s noise levels or facilities (frontage
lanes, jersey barriers or other components).
In conclusion, our analysis indicates that the proposed gravel extraction operation would be in
compliance with the threshold standards in Table 7-1002, based solely to the distance between the
processing facility and adjacent properties. Additional mitigating factors that are present but not included
1 Provided by MAS Environmental LTD, available online at https://noisetools.net/dbmap/
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in our calculations include the perimeter berm, ground absorption, and existing background noise
associated with Interstate 70. The fact that the facility achieves compliance with the LUDC standards of
55 dB threshold even without the incorporation of mitigating factors adds significant confidence to the
conclusion that the Rifle Pit #1 operation will be within the LUDC standards.
Sincerely,
Alex Nees
Senior Ecologist & Team Leader
Attachments:
A. Revised Sound Propagation Map
B. Field-Collected Noise Data