HomeMy WebLinkAbout1.03 General Application Materials_Part404/18/22
C01-1204/19/22MMLRDBISSUED FOR GARFIELD COUNTY REVIEW0-------------------------JOB NO.
SCALEDATEREVISIONSNO.DATEDWN.CHK.ELECTRIC POWER ENGINEERING, INC.12600 W. COLFAX AVE, STE. C500LAKEWOOD, CO 80215(303) 431-7895 www.neieng.com1691 300 COUNTY ROAD, PARACHUTE, CO-
3704.002 CIVILSITE DETAILSHIGH MESA-1
MINIMUM ULTRAVIOLET STABILITY
MINIMUM GRAB TENSILE STRENGTH
IN THE MACHINE DIRECTION
MINIMUM GRAB TENSILE STRENGTH
IN THE CROSS MACHINE DIRECTION
MAXIMUM APPARENT OPENING SIZE
EQUIVALENT STANDARD SIEVE
MINIMUM PERMITTIVITY
ASTM D 4355 70%
ASTM D 4491 0.05 SEC
ASTM D 4751 NO. 30
100 LBS.
120 LBS.
ASTM D 4632
ASTM D 4632
VALUE *METHOD
MAXIMUM APPARENT OPENING SIZE
IN THE CROSS MACHINE DIRECTION
MINIMUM GRAB TENSILE STRENGTH
IN THE MACHINE DIRECTION
MINIMUM GRAB TENSILE STRENGTH
TEST REQUIREMENT
-1
MAXIMUM PERMITTIVITY ASTM D 4491 0.135 SECOR 10 gpm/sq ft at 50 mm
constant head.
MINIMUM SPECIFIED VALUES.)
THE AVERAGE OF MINIMUM TEST RESULTS ON ANY ROLL IN A LOT SHOULD MEET OR EXCEED THE
* ALL NUMERICAL VALUES REPRESENT MINIMUM/MAXIMUM AVERAGE ROLL VALUES. (FOR EXAMPLE,
PERCENTAGE OF STRENGTH RETAINED
AFTER 500 HOURS OF EXPOSURE
NOTE:
1.THE GEOTEXTILE FABRIC SHALL BE PLACED IN THE EXCAVATED TRENCH, BACKFILLED, AND COMPACTED TO THE
EXISTING GROUND SURFACE.
2.WOODEN SUPPORT STAKES SHALL BE A MINIMUM DIMENSION OF 1-1/8" x 1-1/8" AIR OR KILN DRIED OF HICKORY
OR OAK AND 4 FEET LONG. STEEL POSTS SHALL BE STUDDED "TEE" OR "U" TYPE WITH A MINIMUM WEIGHT OF 1.3
POUNDS PER LINEAL FOOT AND 5 FEET LONG. POST SPACING SHALL BE A MAXIMUM OF 8 FEET FOR WOVEN
FABRIC AND 3 FEET FOR NON-WOVEN FABRIC.
3.THE GEOTEXTILE FABRIC SHALL BE ATTACHED DIRECTLY TO THE UPSLOPE SIDE OF WOODEN POSTS WITH 0.5
INCH STAPLES IN AT LEAST 3 PLACES, OR WITH WOODEN LATH AND NAILS. ATTACHMENT TO STEEL POSTS WILL
BE BY WIRE FASTENERS OR 50 POUND PLASTIC TIE STRAPS ON THE UPSLOPE SIDE.
4.THE GEOTEXTILE FABRIC SHALL CONSIST OF EITHER WOVEN OR NON-WOVEN POLYESTER, POLYPROPYLENE,
STABILIZED NYLON, POLYETHYLENE, OR POLYVINYLIDENE CHLORIDE. NON-WOVEN FABRIC MAY BE NEEDLE
PUNCHED, HEAT BONDED, RESIN BONDED, OR COMBINATIONS THEREOF. ALL FABRIC SHALL MEET THE
FOLLOWING REQUIREMENTS:
TYPICAL SECTION
EXISTING SOIL18" MIN.
6"
GEOTEXTILE FABRIC
SEE NOTE 4 FILL SLOPE
TOE ANCHOR
8'-0" MIN.
COMPACTED BACKFILL
6"
FLOW DIRECTION
FLOW DIRECTIONGEOTEXTILE FABRIC
WOOD POSTSTAPLE ALL AROUNDSTAPLE ALL AROUND
SUPPORT STAKE
SEE NOTE 2
*MAINTENANCE*
1.INSPECT ROLLED EROSION CONTROL PRODUCTS AT
LEAST WEEKLY AND AFTER EACH SIGNIFICANT (1/2 INCH
OR GREATER) RAIN FALL EVENT REPAIR IMMEDIATELY.
2.GOOD CONTACT WITH THE GROUND MUST BE
MAINTAINED, AND EROSION MUST NOT OCCUR BENEATH
THE RECP. ANY AREAS OF THE RECP THAT ARE
DAMAGED OR NOT IN CLOSE CONTACT WITH THE
GROUND SHALL BE REPAIRED AND STAPLED.
3.CHECK FOR GENERAL SIGNS OF EROSION, INCLUDING
VOIDS BENEATH THE MAT. IF VOIDS ARE APPARENT, FILL
THE VOID WITH SUITABLE SOIL AND REPLACE THE
EROSION CONTROL BLANKET, FOLLOWING THE
APPROPRIATE STAKING PATTERN.
4.CHECK FOR DAMAGED OR LOOSE STAKES AND SECURE
LOOSE PORTIONS OF THE BLANKET.
5.IF EROSION OCCURS DUE TO POORLY CONTROLLED
DRAINAGE, THE PROBLEM SHALL BE FIXED AND THE
ERODED AREA PROTECTED.
6.MONITOR AND REPAIR THE RECP AS NECESSARY UNTIL
GROUND COVER IS ESTABLISHED.
3
8 4
5
2
7
6
1
* HORIZONTAL STAPLE SPACING SHOULD BE ALTERED
IF NECESSARY TO ALLOW STAPLES TO SECURE THE
CRITICAL POINTS ALONG THE CHANNEL SURFACE.
** IN LOOSE SOIL CONDITIONS, THE USE OF STAPLE
OR STAKE LENGTHS GREATER THAN 6" (15 CM) MAY
BE NECESSARY TO PROPERLY ANCHOR THE BLANKETS.
A. OVERLAPS AND SEAMS
B. PROJECTED WATER LINE
C. CHANNEL BOTTOM/SIDE
SLOPE VERTICES
CRITICAL POINTS6"(15CM)4"-6"
(10CM-15CM)
12"
(30CM)
6"
(15CM)6"(15CM)6"(15CM)4"
(10CM)4"(10CM)2"-5"
(5CM-12.5CM)
C
BA
B
C
A
NOTES:
1.INSTALLATION TO BE COMPLETED IN ACCORDANCE WITH
MANUFACTURER'S SPECIFICATIONS.
2.IN LOOSE SOIL CONDITIONS THE USE OF STAPLE OR STAKE
LENGTHS GREATER THAN 6" (15CM) MAY BE NECESSARY TO
PROPERLY SECURE THE BLANKETS.
2
4
5
3B
1
3A
SLOPE INSTALLATION
2"-5"
(5CM-12.5CM)12"
(30CM)6"(15CM)6"
(15CM)
3"
(7.5CM)
NOTES:
1.INSTALLATION TO BE COMPLETED IN ACCORDANCE WITH MANUFACTURER'S SPECIFICATIONS.
2.IN LOOSE SOIL CONDITIONS THE USE OF STAPLE OR STAKE LENGTHS GREATER THAN 6" (15CM) MAY
BE NECESSARY TO PROPERLY SECURE THE BLANKETS.
1.PREPARE SOIL BEFORE INSTALLING BLANKETS, INCLUDING ANY NECESSARY APPLICATION OF LIME,
FERTILIZER, AND SEED.
2.BEGIN AT THE TOP OF THE SLOPE BY ANCHORING THE BLANKET IN A 6" (15CM) DEEP X 6" (15CM)
WIDE TRENCH WITH APPROXIMATELY 12" (30CM) OF BLANKET EXTENDED BEYOND THE UP-SLOPE
PORTION OF THE TRENCH. ANCHOR THE BLANKET WITH A ROW OF STAPLES/STAKES
APPROXIMATELY 12" (30CM) APART IN THE BOTTOM OF THE TRENCH. BACKFILL AND COMPACT THE
TRENCH AFTER STAPLING. APPLY SEED TO COMPACTED SOIL AND FOLD REMAINING 12" (30CM)
PORTION OF BLANKET BACK OVER SEED AND COMPACTED SOIL. SECURE BLANKET OVER
COMPACTED SOIL WITH A ROW OF STAPLES/STAKES SPACED APPROXIMATELY 12" (30CM) APART
ACROSS THE WIDTH OF THE BLANKET.
3.ROLL THE BLANKETS (A.) DOWN OR (B.) HORIZONTALLY ACROSS THE SLOPE. BLANKETS WILL
UNROLL WITH APPROPRIATE SIDE AGAINST THE SOIL SURFACE. ALL BLANKETS MUST BE SECURELY
FASTENED TO SOIL SURFACE BY PLACING STAPLES/ STAKES IN APPROPRIATE LOCATIONS AS
SHOWN IN THE STAPLE PATTERN GUIDE. WHEN USING OPTIONAL DOT SYSTEM, STAPLES/STAKES
SHOULD BE PLACED THROUGH EACH OF THE COLORED DOTS CORRESPONDING TO THE
APPROPRIATE STAPLE PATTERN.
4.THE EDGES OF PARALLEL BLANKETS MUST BE STAPLED WITH APPROXIMATELY 2"-5" (5CM-12.5CM)
OVERLAP DEPENDING ON BLANKET TYPE. TO ENSURE PROPER SEAM ALIGNMENT, PLACE THE EDGE
OF THE OVERLAPPING BLANKET (BLANKET BEING INSTALLED ON TOP) EVEN WITH THE COLORED
SEAM STITCH ON THE PREVIOUSLY INSTALLED BLANKET.
5.CONSECUTIVE BLANKETS SPLICED DOWN THE SLOPE MUST BE PLACED END OVER END (SHINGLE
STYLE) WITH AN APPROXIMATE 3" (7.5CM) OVERLAP. STAPLE THROUGH OVERLAPPED AREA,
APPROXIMATELY 12" (30CM) APART ACROSS ENTIRE BLANKET WIDTH.
SLOPE INSTALLATION
CHANNEL INSTALLATION
3
NTS
SILT FENCE INSTALLATION
C01-12
2
NTS
ROLLED EROSION CONTROL PRODUCT INSTALLATION
C01-12
PLAN VIEW
PIPE NOTES:
1) L = LENGTH OF THE RIPRAP APRON.
2) L₂ = RIPRAP TO BE INSTALLED UNDERNEATH 1/3 THE
LENGTH OF FLARED END SECTION (FES).
3) d = 1.5 TIMES THE MAXIMUM STONE DIAMETER BUT NOT
LESS THAN 6 INCHES.
4) IN A WELL-DEFINED CHANNEL EXTEND THE APRON UP THE
CHANNEL BANKS TO AN ELEVATION OF 6 INCHES ABOVE
THE MAXIMUM TAILWATER DEPTH OR TO THE TOP OF THE
BANK, WHICHEVER IS LESS.
5) A FILTER BLANKET OR FILTER FABRIC SHOULD BE
INSTALLED BETWEEN THE RIPRAP AND SOIL FOUNDATION.
RIPRAP
APRON
SECTION 'A-A'
FILTER
FABRIC
d
L
PIPE
L₂
1
1SEE NOTE 4
FES
FES
4
NTS
PIPE OUTLET TO WELL-DEFINED CHANNEL
C01-12
LC
10'1:11:
1
4:1 SLOPE TO
EXISTING
GROUND
4:1 SLOPE TO
EXISTING
GROUND
2% SLOPE (TYP), MIN 1%EDGE OF GRAVELEDGE OF GRAVELPROPERLY COMPACTED AGGREGATE BASE
COMPACTED SUBGRADE
GEOTEXTILE SEPARATION FABRIC (MIRAFI 140N OR
EQUAL)
10'
6" MIN
NOTES:
1.4:1 MAXIMUM SLOPE FROM EDGE OF GRAVEL TO EXISTING GROUND.
2.AGGREGATE BASE COMPACTED TO A MINIMUM OF 95% OF THE SOIL'S MODIFIED
PROCTOR MAXIMUM DRY DENSITY.
3.AGGREGATE BASE COURSE SHOULD CONSIST OF A BLEND OF SAND AND GRAVEL
WHICH MEETS COLORADO DEPARTMENT OF TRANSPORTATION (CDOT) CLASS 5 OR 6
SPECIFICATIONS
4.SUBGRADE TO BE A MINIMUM 12-INCHES OF SCRIFIED, MOISTURE CONDITIONS, AND
RECOMPACTED SOIL.
5.ROAD GRADES ARE TYPICALLY INTENDED TO MATCH ADJACENT GRADE ALLOWING
DRAINAGE TO SHEET FLOW ON AND OFF ROADS EVENLY. FIELD ADJUST ROAD GRADES
OR DITCHE LOCATIONS AS NECESSARY TO PREVENT RUNOFF FROM CONCENTRATING
ALONG ROAD EDGES CAUSING EROSION.
6.ROADS SHALL HAVE 2" OF AGGREGATE BASE ADDED EVERY 5 YEARS, OR AS NEEDED TO
MAINTAIN MINIMUM DEPTH. ROADS SHALL UNDERGO SEMI-ANNUAL MAINTENANCE.
2% SLOPE (TYP), MIN 1%
1
NTS
20 FT WIDTH SOLAR ACCESS ROAD DETAIL
C01-12
NOTES:
1.EXCAVATE TO 4 INCHES BELOW THE PROPOSED PIPE ELEVATION.
2.PROVIDE 4 INCHES STONE BEDDING AND 4 INCHES STONE BACKFILL.
3.WHERE BELL AND SPIGOT PIPE IS USED, PROVIDE RECESSES TO RECEIVE PIPE BELL.
4.UNDERCUT UNSUITABLE MATERIAL AS DIRECTED BY THE ENGINEER AND BACKFILL WITH STONE OR
OTHER APPROVED MATERIAL.
5.WHERE NECESSARY, TEMPORARILY DIVERT SURFACE WATER TO MAINTAIN A DRY CONDITION IN THE
PIPE FOUNDATION. DIRECT THIS TEMPORARY FLOW INTO SUITABLE EROSION CONTROL DEVICES.
BACKFILL INITIAL LIFT: 12"MAX. NON TRAFFIC AREAS:12" MAX. LIFTS TRAFFICAREAS: 6" MAX. LIFTSCOMPACTION: 95% MAX.DRY DENSITY (STANDARDPROCTOR)
NO. 5, 57, OR 67 STONE
12" BED OF COMPACTED CRUSHER RUN
5
NTS
CULVERT CROSSING FILL AND COVER
C01-12
04/19/2022
04/18/22
C01-1304/19/22MMLRDBISSUED FOR GARFIELD COUNTY REVIEW0-------------------------JOB NO.
SCALEDATEREVISIONSNO.DATEDWN.CHK.ELECTRIC POWER ENGINEERING, INC.12600 W. COLFAX AVE, STE. C500LAKEWOOD, CO 80215(303) 431-7895 www.neieng.com1691 300 COUNTY ROAD, PARACHUTE, CO-
3704.002 PV CIVILSITE DETAILSHIGH MESA04/19/2022
20'-0"
40'-0"5500549454965498550255045492
FRONT VIEWRIGHT VIEW
ISOMETRIC VIEW
04/18/22
C01-1404/19/22MMLRDBISSUED FOR GARFIELD COUNTY REVIEW0-------------------------JOB NO.
SCALEDATEREVISIONSNO.DATEDWN.CHK.ELECTRIC POWER ENGINEERING, INC.12600 W. COLFAX AVE, STE. C500LAKEWOOD, CO 80215(303) 431-7895 www.neieng.com1691 300 COUNTY ROAD, PARACHUTE, COAS SHOWN
3704.002 PV CIVILSITE DETAILSHIGH MESAMODULES
20' GRAVEL ACCESS ROAD
O&M SHED CONCRETE PAD
6"
3'-0"
MIN
2% SLOPE (TYP)
4:1 SLO
P
E
VARIES BASED ON GRADE SLOPE
WORKING SURFACE ELEVATION
(4" ROAD BASE GRAVEL)
FINISH FLOOR ELEVATION
(MIN 1' ABOVE FLOODPLAIN)
GRASS COVER
PLAN VIEWSECTION VIEW
2
NTS
TYPICAL EQUIPMENT PAD GRADING DETAIL
C01-14
1a
1"=20'
O&M SHED - GRADING DETAIL
C01-14
DCCOMMLVHVLVAUXXFMRBESSAXBESSBXHVX.XX MVAXFMRLVMTS INVERTERSDCCOMMLVHVAC 2HVAC 1HVAC 2HVAC 138'-0"70'-0"
WORKING SURFACE
4'-6"
6'-6"
3'-0"
6'-0"
8'-6" MAX
EQUIPMENT HEIGHT
40'-0"7'-11.98"
SWITCHGEAR INVERTER/
BESS PAD
3
NTS
VISUAL SCREENING BERM DETAIL
C01-14
BACKFILL
2:1 SLO
P
E
2:1 S
L
O
P
E
26'-0"
2'-0"
6'-0"
1b
NTS
O&M SHED - ASSEMBLY DETAIL
C01-14
04/19/2022
12'-0"
PRESS TREATED WOOD
POST 6" TO 7" DIA.
12.5 GAUGE DOUBLE WRAPPED HIGH
TENSILE DIAGONAL BRACE WIRES WITH
CLASS 3 GALVANIZED COATING (TYP.)
PROP. END BRACE SPECS
NOT TO SCALE
PRESS TREATED WOOD
POST 5" TO 6" DIA.
15'-0"
PRESS TREATED WOOD
POST 5" TO 6" DIA.
PROP. LINE POST SPECS
NOT TO SCALE
PRESS TREATED WOOD
POST 5" TO 6" DIA.
8'-0"
3'-0"
12'-0"
PRESS TREATED WOOD
POST 6" TO 7" DIA.
PRESS TREATED WOOD
POST 5" TO 6" DIA. (TYP.)
12'-0"
8'-0"
3'-0"
12.5 GAUGE DOUBLE WRAPPED HIGH
TENSILE DIAGONAL BRACE WIRES WITH
CLASS 3 GALVANIZED COATING (TYP.)
PRESS TREATED WOOD
POST 6" TO 7" DIA.
8'-0"8'-0"
8'-0"
4'-0"
KNOX BOX OR SIMILAR
RAPID ENTRY SYSTEM
PRESS TREATED WOOD
POST 6" TO 7" DIA. (TYP.)
12.5 GAUGE DOUBLE WRAPPED HIGH
TENSILE DIAGONAL BRACE WIRES WITH
CLASS 3 GALVANIZED COATING (TYP.)1691 300 COUNTY ROAD, PARACHUTE, CO04/18/22 NTS
3704.002 PV CIVILSITE DETAILSC01-15HIGH MESA04/19/22MMLRDBISSUED FOR GARFIELD COUNTY REVIEW0-------------------------PRELIMINARY
NOT FOR CONSTRUCTION
FOR REVIEW & APPROVAL ONLY JOB NO.
SCALEDATEREVISIONSNO.DATEDWN.CHK.ELECTRIC POWER ENGINEERING, INC.12600 W. COLFAX AVE, STE. C500LAKEWOOD, CO 80215(303) 431-7895 www.neieng.comNOTE:
1.DETAILED FENCING AND GATE SPECIFICATIONS TO BE SUPPLIED BY
FENCING CONTRACTOR.
2.FENCING TO BE SUBSTANTIALLY SIMILAR TO THE REPRESENTATIVE
DETAIL SHOWN ON THESE PLANS. GUIDELINES FOR EXCLUSION FENCING
DERIVED FROM "FENCING WITH WILDLIFE IN MIND" DOCUMENT FROM
COLORADO PARKS AND WILDLIFE (CPW)
04/19/2022
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 27
Solar Energy facilities are low-profile, unobstructive developments with very little impact to the
surrounding lands or uses. While visible from within the property lines, neighboring parcels lack
significant viewshed of the Project given its location on a low mesa above surrounding valley properties.
Further, there is little in the profile or nature of the solar array once installed that would result in
negative impacts to adjacent property, provided its quiet and emission-free operation with limited
maintenance visits by technicians. In the case of this project, the solar facility will be sited on vacant
land with plenty of distance to either nearby rights-of-way or residences. At its closest point, the solar
array will be approximately 70ft from the edge of Richardson Road’s 30ft easement, and at least 250ft or
more from the Klebold’s’ residence.
At a distance of nearly 3.5 miles to more populated parts of Parachute and at an elevation nearly 400’
higher than the valley floor and town limits, visual impact from the installation is deemed to be
negligible. On the property, AES is proposing to install an 8ft tall, wildlife-friendly game fence around
the facility as detailed in the Site Plan in Section B2 on page C01-11. This will serve to soften the visual
impact of the installation and will present a less industrial aesthetic than standard chain link fencing
while meeting electrical code and operational safety requirements. The proposed fencing is of the
specification employed by Colorado Department of Transportation along public right-of-way in the area,
and as such will not look out of place.
Given the lack of adjacent property owners with views to the Project coupled with the arid natural
setting, this application is not proposing any additional landscaping measures beyond those
recommended in the weed and revegetation management plan detailed in the following section;
however, AES and the Klebolds have agreed to installation of a six foot tall earthen berm along the
irrigation ditch running the Project’s perimeter closest to their residence in the northwest section of the
property.
Please see Section B2 and page C01-05 for the location and C01-10 of the Site Plan for a cross section
of the proposed earthen berm.
LANDSCAPING PLAN
Section B3
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 28
Please see the following pages for the Weed Management and Re-Vegetation plan prepared by HDR
Consulting.
WEED MANAGEMENT AND RE-VEGETATION PLAN
Section B4
MARCH 2022
Vegetation Management Plan
Holy Cross Photovoltaic + BESS Portfolio High Mesa Solar Project
Garfield County, Colorado
Prepared for:
Prepared by:
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
March 2022 | i
Abbreviations and Acronyms
AES AES High Mesa Solar, LLC
BESS Photovoltaic + Battery Storage
C.R.S. Colorado Revised Statutes
CDA Colorado Department of Agriculture
GCVM Garfield County Vegetation Management
GPS Global Positioning System
MW Megawatt
NRCS Natural Resources Conservation Service
VMP Vegetation Management Plan
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
March 2022 | ii
Contents
Acronyms and Abbreviations ............................................................................ Inside Front Cover
1 Introduction and Project Description ..................................................................................... 1
2 Purpose and Need ............................................................................................................... 1
2.1 Project Responsibilities ................................................................................................ 3
2.1.1 AES (Project Proponent) ...................................................................................... 3
2.1.2 Construction Contractor ....................................................................................... 3
2.1.3 Reclamation Contractor ....................................................................................... 3
2.1.4 Garfield County (Regulatory) ............................................................................... 3
3 Reclamation and Revegetation Measures ............................................................................ 4
3.1 Proposed Native Seed Mix .......................................................................................... 4
3.2 Seeding Approach ....................................................................................................... 4
3.3 Reclamation Success Criteria ...................................................................................... 5
4 Weed Management .............................................................................................................. 7
4.1 Recorded Weed Occurrences ...................................................................................... 7
4.2 Integrated Weed Management ..................................................................................... 7
4.3 Chemical Control ......................................................................................................... 9
4.4 Mechanical Control ...................................................................................................... 9
4.5 Cultural Control .......................................................................................................... 10
4.6 Wash Stations ........................................................................................................... 10
5 Monitoring, Reporting, and Remedial Action .......................................................................11
5.1 Revegetation ............................................................................................................. 11
5.2 Noxious Weeds Management .................................................................................... 11
5.3 Reporting and Remedial Actions ................................................................................ 12
6 References ..........................................................................................................................13
Appendices
Appendix A: Control Methods for Project Weed Species
Figures
Figure 1. Project Area Location .................................................................................................. 2
Figure 2. Project Area Vegetation .............................................................................................. 6
Tables
Table 1. Seed Mixes and Application Rates (Upland Mix) .......................................................... 4
Table 2. Weed Species Detected in the Project Area ................................................................. 7
Table 3. Integrated Weed and Vegetation Management Techniques ......................................... 8
Table 4. Project Contacts ..........................................................................................................12
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
March 2022 | 1
1 Introduction and Project Description
AES High Mesa Solar, LLC (AES) is proposing a paired Photovoltaic + Battery Storage (BESS) project
(Project) to support Holy Cross Energy’s 2030 goal of using 100 percent renewable energy. The
Project involves the development of a greenfield solar array in Garfield County, Colorado, targeting up
to 16 megawatt (MW) direct current / 10 MW alternating current plus 20 megawatt hours of battery
storage. The proposed Project site is approximately 4 miles southwest of Parachute, Colorado within
Section 35, Township 7 South, Range 96 West (see Figure 1). Construction is scheduled to begin
after May 1, 2022 and conclude within 6 to 8 months.
2 Purpose and Need
This document serves as the Vegetation Management Plan (VMP) for the Project. This VMP
comprises three main sections: (1) reclamation and revegetation; (2) weed management; and (3)
monitoring, reporting, and remedial action.
For the purposes of this VMP, noxious weeds are defined as those plants listed under the Colorado
Noxious Weed Act, Colorado Revised Statue (C.R.S) 35-5.5-101-119. The Colorado Department of
Agriculture (CDA) is responsible for the monitoring and control of noxious weeds in the state. The
species of concern are categorized as A-, B-, or C-rated plants according to their current level of
infestation and threat, with A-rated being of highest concern. Generally, the categories are defined as
follows.
• A-Rated: Species in Colorado are designated for eradication wherever they are found.
• B-Rated: Those species for which management is designed to eradicate, contain, or suppress
in portions of the state designated by the commissioner in order to stop their continued spread.
• C-Rated: Widespread and well-established noxious weed species for which control is
recommended but not required, although local governing bodies may require management.
The purpose of this VMP is also to identify and detail the necessary measures to achieve Project site
reclamation and revegetation. The following procedures and standards would be implemented and
upheld toward the successful reclamation of construction-related disturbances:
• reclamation performance standards as defined by Garfield County and the State of Colorado
• environmental conditions pertinent to reclamation activities and success
• vegetation and soil management techniques
• reclamation procedures, including site preparation, mulching, and seeding
• reclamation measures for disturbance on wetland (avoidance) and upland habitats
(revegetation)
• monitoring and reporting requirements
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
March 2022 | 2
Figure 1. Project Area Location
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
March 2022 | 3
2.1 Project Responsibilities
Compliance with this VMP is contingent upon Project planning and execution of the following roles
and responsibilities.
2.1.1 AES (Project Proponent)
AES would be responsible for the following:
• Ensure the appropriate reviews, approvals, and implementation of this VMP
• Appoint and manage a qualified, licensed reclamation contractor
• Coordinate with the reclamation contractor and Garfield County regarding scheduled
vegetation management activities
2.1.2 Construction Contractor
The construction contractor would be responsible for the following:
• Project construction related activities
• Oversee the various subcontracted construction companies working on the Project
• Implement applicable pre-construction and construction phase restoration (e.g., recontouring
and stabilization) and impact minimization measures (e.g., stormwater control measures)
• Identify and maintain weed wash stations
• Ensure that vehicles and materials are clean prior to Project site entry or exit
2.1.3 Reclamation Contractor
The reclamation contractor would be responsible for the following:
• Implement and monitor revegetation of Project disturbances
• Weed management planning, implementation, and monitoring
• Conduct weed treatments and manage herbicide application records
• Implement and monitor the efficacy of weed treatments
• Annual mowing in late June or early July
• Coordinate with Garfield County to document weed treatments
2.1.4 Garfield County (Regulatory)
Garfield County would be responsible for the following:
• Approve this VMP and other Project management plans
• Attend annual meetings (as necessary) with AES and the reclamation contractor
• Approve seed mixes and herbicides used on the Project site
• Inspect the Project site for compliance and provide regulatory guidance
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
March 2022 | 4
3 Reclamation and Revegetation Measures
3.1 Proposed Native Seed Mix
AES is responsible for controlling soil erosion and gullying in the Project area during construction and
operation. The Project design would avoid the accumulation of excessive heads of water and
encroachment on streams. AES would revegetate or otherwise stabilize all ground where the soil has
been exposed as a result of construction activities, maintenance, and operation. AES will also
construct and maintain necessary preventive measures to supplement the vegetation. A native seed
mix for the Project area is provided in Table 1 below. This seed mix was identified in coordination with
the Natural Resources Conservation Service (NRCS).
Seeds used for revegetation would be certified noxious weed free. This would be accomplished by
purchasing seed mixes from county approved vendors or testing seed lots through an independent
laboratory. The results of the seed testing would be presented to the Garfield County vegetation
manager prior to use on the Project. Approved seed mixes would be free of noxious weeds, common
weeds, and crop weeds. Unless purchased from a trusted vendor, manufacture labels on seed bags
are insufficient proof of certified weed free seed.
Table 1. Seed Mix and Application Rates (Upland Mix)
Seed Mix Species Cultivar Percent of
Seed Mix
Total PLS
(lbs)
PLS
(lbs/acre)
PLS
(seeds/ft2)
Western wheatgrass (Pascopyrum smithii) arriba 20% 618 8 3.20
Blue grama (Bouteloua gracilis) alma 20% 95 8 0.49
Galleta grass (Hilaria jamesii) viva 15% 107 6 0.56
Indian ricegrass (Achnatherum hymenoides) Paloma 10% 143 4 0.74
White sage (Artemisia ludoviciana) wild 10% 13 4 0.07
Western yarrow (Achillea millefolium) wild 10% 12 4 0.06
Bottlebrush squirreltail (Elymus elymoides) tusas 5% 88 2 0.45
Blanketflower (Gaillardia aristata) wild 5% 84 2 0.44
Sandberg bluegrass (Poa secunda) wild 5% 19 2 0.10
TOTAL 100% 1179 40 6.11
Source: NRCS 2021; PLS = Pure Live Seed
3.2 Seeding Approach
The reclamation contractor would identify areas requiring seeding and would determine the necessary
level of effort and approach based on surface disturbance, soil compaction, and the condition of
underlying root systems after construction. A drill seed approach will be used, as applicable to the
particular area(s), to reseed after disturbed soils are recontoured and/or roughened for seeding. Sites
where soils are not physically displaced during construction would typically retain the root systems
and native seed bank, which would permit natural regrowth of existing vegetation. Therefore, areas
such as access roads and staging areas would be assessed on a site-specific basis for prescribed soil
preparation and reseeding efforts.
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Vegetation Management Plan
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Soil preparation would occur prior to reseeding to promote maximum seed germination. All soil ripping,
soil harrowing, and seeding operations would be performed as close to parallel to the topographic
contours as possible. Following seeding, the surface would be dragged, harrowed, and/or hand raked
as needed based on site conditions. After seeding, cleared vegetation would be spread throughout
reclaimed areas to imitate natural colors and textures in the landscape and to create microclimates
that promote vegetation establishment and plant diversity.
Seeding success is influenced by temperature, precipitation, wind, aspect/slope, soil type, and other
environmental factors. The best germination occurs when temperatures are above freezing and during
high precipitation. In Colorado, optimal seeding conditions for cool-season species usually occur in
the late fall and early spring. Therefore, seeding should be conducted between October 25 and April
30. However, seeding would not be conducted during windy conditions or when the ground is
excessively wet, frozen, snow covered, extremely dry, cloddy, hard, or otherwise untillable. The
reclamation contractor would consider the collective environmental factors when seeding application
is conducted across the Project site. Site reclamation is anticipated to be achieved within four growing
seasons or when the Project area has reached around 70 percent of pre-construction vegetation
density. The reclamation contractor would monitor revegetation progress until such time that
reclamation success is approved by the Garfield County vegetation manager.
The revegetated site would be mowed annually between June 15 and July 15 for the duration of the
solar facility’s operational lifespan. Annual mowing in early summer would help to mechanically control
weeds while minimizing damage to native plants. Most native plants would mature in mid- or late
summer. This is expected to support the native plant community and promote natural competition of
the native community with weed species (see Figure 2, page 6).
3.3 Reclamation Success Criteria
The goal of post-construction reclamation is to return the land to a state approximating pre-
construction conditions. This includes reclamation of the landform and natural vegetative communities,
hydrologic systems, visual resources, and wildlife habitats. Successful reclamation would meet the
following reclamation success criteria:
• Erosional features are equal to or less than those in the surrounding area. Water infiltrates the
soil rather than running off the surface.
• Noxious weed species’ cover is equal or less than that present before construction.
• Temporary soil disturbances are recontoured to the original topography and grade.
• Disturbances to soils and vegetation are not obvious to the untrained eye, with the exception
of permanently disturbed areas, such as access roads.
• Revegetated plant densities (not including weed species) are at least 70 percent of
representative pre-construction plant cover. The percentage threshold would be compared to
representative vegetation communities of grasses, forbs, and sub-shrubs. Shrubs and tree are
not a component of the seed mix.
• Grasses, forbs, and sub-shrubs must be resilient, as demonstrated by vigor with well-developed
root systems and the ability to produce viable seed.
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
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Figure 2. Project Area Vegetation
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
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4 Weed Management
4.1 Recorded Weed Occurrences
Surveys were conducted within and adjacent to the Project area boundary. During the surveys
conducted on November 4, 2020, and May 25, 2021, three noxious weed species were documented
in the Project area. List A noxious weed species were not observed within or near the Project area.
The recorded noxious weeds were concentrated along roadsides and adjacent to the center-pivot
agricultural field (see Table 2 and Figure 2). Weeds recorded in undisturbed areas were primarily
limited to downy brome (Bromus tectorum).
Table 2. Weed Species Detected in the Project Area
Species Name CDA Weed
Listing
Population Size in
Project Area Occurrence Pattern and Location
Downy brome
(Bromus tectorum) C Large –Thousands
of plants
Concentrated along roadsides, agricultural
areas, and disturbed areas. Also occurs to a
lesser degree among sagebrush.
Musk thistle
(Carduus nutans) B Small – A few dozen
plants
Small occurrences in disturbed areas
associated with drainages. Isolated plants
occur along the mapped drainage channel in
the Project area
Russian thistle
(Salsola tragus) No Status Large – Thousands
of plants
Concentrated along roadsides, surrounding
agricultural areas, and other disturbed areas
Source: CDA 2021
4.2 Integrated Weed Management
Integrated Weed Management is the implementation of multiple weed control measures into a focused
weed management approach. Preventing the spread of noxious weeds is the VMP’s first priority. AES
would conduct its construction activities consistent with the objective of minimizing the potential for the
introduction and spread of noxious weed species. An integrated weed management strategy would be
used to control weeds during construction and operation of the Project.
AES would adhere to the following weed management guidelines:
• Weed control would include a combination of mechanical, chemical, and cultural methods.
• Remove all excess soil and plant debris from construction equipment before entering the
Project area to reasonably ensure that noxious weed seeds or plant parts are not introduced.
• All erosion control devices, straw, mulch, soils, aggregate, and seed would be noxious weed
free or otherwise inherently free of weeds prior to use on the Project.
• Seed mixes would be purchased from a county approved vendor or would otherwise be
submitted for lab analysis prior to use on the Project.
• Minimize ground disturbance during construction. Upon completion of construction, disturbed
areas would be reseeded between October 25 and April 30.
• Bi-annual (spring and fall) noxious weed surveys and treatment are recommended.
• Noxious weed treatment and monitoring would occur in conjunction with revegetation
inspections for four years post-construction. Additional seeding and herbicide treatments
would occur as needed during annual inspection events.
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Vegetation Management Plan
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In general, weed management would be consistent with the Colorado Noxious Weed Act, Garfield
County standards for reclamation and weed management, and applicable federal regulations. While
AES is only responsible for treating weeds that occur within the Project area, consideration would be
given to the threat posed from integrated weed treatment on other sensitive resources, such as
special-status species and aquatic features. Furthermore, AES would coordinate with landowners to
identify any specific restoration measures, avoidances, risk assessment notifications, or other
requests. The Project area would be inspected and treated (as needed) for weed occurrences during
the construction and post-construction phases.
If construction begins in the spring or otherwise during the growing season, weed treatment with
herbicides prior to the start of construction would help limit the spread of weeds throughout the Project
area during construction. AES would focus on the treatment and control of concentrated populations
of noxious weeds located in areas proposed for disturbances. Construction would start in weed-free
areas and then move to infested areas to minimize the potential spread of weed seeds and plant parts.
Biological means of weed management have not been proposed for use on the Project because other
integrated weed control measures would be more effective and/or no reliable biological control exists
for the specific weed species in the Project area.
The Project would adhere to treatment methods recommended by the Garfield County vegetation
manager and outlined within the county noxious weed management plan (GCVM 2016). Methods to
control weeds in the Project area would include an integrated approach using mechanical, chemical,
and cultural measures. These three measures are detailed in the following sections and in Table A.1
(Appendix A). Because weed control methods and approved herbicides can change intermittently, the
reclamation contractor is encouraged to contact the Garfield County vegetation manager annually to
confirm the recommended control methods. The integrated weed management techniques are
summarized in Table 3 and discussed further in Section 4.3 through 4.6.
Table 3. Integrated Weed and Vegetation Management Techniques
Activity Date1 Responsibility Comment
2022 (Construction)
Noxious weed
inspection / herbicide
application
spring and fall Reclamation
Contractor
• 30 days prior to construction and based
upon weed species’ growing season
• Fall to control seeding of weeds
Post-herbicide
application inspection
10 to 14 days after
treatment
Reclamation
Contractor
Application form/report documenting
herbicide treatment and efficacy submitted
to Garfield County
Wash stations During Construction Construction
Contractor
Stations would be located at project site
entry and exit points
Post-Construction (up to 4 seasons)
Reclamation
inspections and noxious
weed treatments
spring and fall
(up to 4 seasons)
Reclamation
Contractor
Application form/report documenting
herbicide treatment and efficacy would be
submitted to Garfield County
Native Seed Mix
application
Post-construction
(Oct 25 to April 30)
Reclamation
Contractor
May require more than one round of seed
application
Annual mowing /
mechanical vegetation
maintenance
June 15 – July 15 Reclamation
Contractor
Activities would be ongoing for the life of the
solar facility
1 – The precise application date(s) would be determined by the contractor based upon the target species and other
seasonal and environmental conditions
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Vegetation Management Plan
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4.3 Chemical Control
It is important to treat small infestations of weeds chemically (List A and B species to be eradicated)
as soon as possible. Table A.1 lists which weed species respond best to chemical control. Herbicides
are most effective when sprayed at specific stages of a weed’s lifecycle (GCVM 2016). The application
of herbicide to control noxious weeds would occur each year, as needed, in the late spring or early
summer. Specific chemical recommendations are available from the Garfield County Vegetation
Management (GCVM) Department. All herbicide applications would comply with applicable labels,
laws, regulations, and permit stipulations. Furthermore, any use of an herbicide inconsistent with the
label can lead to injury of crops, humans, animals, and the environment. Therefore, chemical
treatments would be conducted by a licensed herbicide applicator according to individual chemical
and label requirements.
All herbicides are required to have a Human Health Risk Assessment. Notification of registered
pesticide-sensitive persons must be given in accordance with C.R.S 35-10-112, and Part 12 of the
Pesticide Applications Act. Applicators are required to notify registered individuals prior to applying
herbicides on adjacent properties. For information about the registry, call the Colorado Department of
Agriculture at 303-239-4146. Furthermore, the reclamation contractor would provide Garfield County
a list of proposed herbicides to be used for treatment efforts each year. The herbicide list is subject to
change due to current site conditions, efficacy of treatments, availability of new herbicides, and other
factors. Recommended herbicides can be found within the Garfield County Noxious Weed
Management Plan (GCVM 2016).
Chemical application equipment would vary according to the time of year, plant phenology, size of
infestation, chemical being applied, non-target species present, and weed cover in the infested area.
The equipment chosen would provide the most effective weed control while also reducing unnecessary
environmental impacts, such as application outside of infested areas. ATVs and trailered sprayers
would be used for most herbicide application. Spot applications would be used preferentially to avoid
non-target plants or limit contamination of sensitive resource areas (i.e., wetlands or stream). Digital
copies of herbicides, labels, and safety data sheets would be managed by the reclamation contractor
and available upon request.
AES would initiate noxious weed management efforts for high-priority species and concentrated weed
occurrences. Treatment efforts would be limited to the property for which AES has management
responsibility, which consists of the Project area, access roads, and other areas used for staging
materials or equipment. In addition, AES would prepare and submit reports to Garfield County detailing
all weed treatments (see Section 5.3).
4.4 Mechanical Control
Mechanical control would include mowing, cutting, and hand removal of weeds. Table A.1 lists and
details which weed species respond best to mechanical control. The extent of the infestations across
the Project area would limit the effectiveness of post-construction mechanical control methods to spot
control. Also, mechanical control methods used across large areas could increase soil erosion and
encourage additional weed species’ colonization or spread. However, small infestations (less than 0.5
acre) can be controlled effectively using mechanical control methods.
Although not a primary method of weed management, mechanical control would be used when
chemical control is ineffective or otherwise prohibited. Mechanical control would be used during the
construction process when existing vegetation is removed to permit for the installation of the
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
March 2022 | 10
underground conductor, aboveground conductor panels, and associated design infrastructure.
Roadbase aggregate would be used on the Project area interior access roads. Disturbed soils and
vegetation would not be removed from the site as a result of access road work (grading and
recontouring). Sagebrush vegetation would be mowed, chipped, and spread onsite to create
microhabitat and help retain topsoil, encourage the regrowth of existing native vegetation, and promote
reclamation of reseeded areas. Prescribed burns and grazing would not be used as a method of
mechanical control on the Project.
4.5 Cultural Control
Cultural control methods or management practices are those that favor the growth of desirable plants
over noxious weeds, including maintaining optimum fertility and plant moisture status, revegetating at
optimum density and spatial arrangement, and planting species most suited to a particular area.
Techniques include dense seeding, fertilization, mulching, careful irrigation practices, sensible grazing
regimes, and improved land management practices (GCVM 2016).
Where possible, the Project would limit the establishment of new weed infestations by minimizing
disturbance and weed seed dispersal while maintaining the native vegetation community.
Disturbances would be revegetated with an approved native seed mix. Using native plants or seeds
to revegetate disturbed areas helps to control the degradation of native ecosystems, limit the need for
herbicides, and conserve water. Project construction would also avoid disturbances on wetlands and
streams, thereby minimizing the potential spread of weed species associated with mesic soils. Table
A.1 lists which weed species respond best to cultural control.
4.6 Wash Stations
Equipment and vehicle cleaning is an important weed control component of Project activities. Mud and
soil on equipment and vehicles have the potential to carry weed seeds or propagative plant parts to or
from the Project area. Implementing the following proactive measures and approaches to weed
management would significantly reduce the potential for Project activities to spread noxious weed
species:
• Vehicles would be inspected and washed to remove all mud and soil that could harbor weed
parts (i.e., roots, seeds, and vegetation) prior to entering or exiting the Project area.
• Wash and inspection stations would be located at Project area entrance points.
• Clean equipment may enter or exit the Project area without washing, assuming the
equipment has been properly inspected.
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5 Monitoring, Reporting, and Remedial Action
Monitoring revegetation and noxious weed occurrences in the Project area would occur annually for
four years post-construction. Surveys would be conducted by qualified personnel at least once a
season to ascertain the nature and distribution of existing and new noxious weed occurrences.
Noxious weed occurrences would be evaluated using the management guidelines described in
Section 4, and appropriate management methods would be implemented to control further spread and
encourage the growth of native vegetation.
5.1 Revegetation
The reclamation contractor would conduct annual reclamation monitoring, reporting, and remedial
action after construction is complete. Annual monitoring and reporting of progress for all reclaimed
areas would occur for four years or until the revegetated areas reach 70 percent cover as compared
to pre-construction native vegetation. Monitoring would consist of qualitative assessments at sites
where revegetation progress and soil stabilization would be compared to adjacent native plant
community conditions. Monitoring sites used to prove attainment of reclamation standards would be
identified by the reclamation contractor. Reclamation success would be approved by Garfield County
when disturbed areas meet the reclamation success criteria listed in Section 3.3.
Annual qualitative and quantitative performance monitoring would be conducted by the reclamation
contractor to determine reclamation effectiveness and revegetation of reseeded areas. Post-
construction monitoring would begin in the growing season in the first year following construction and
would occur annually until conditions meet the success criteria. Post-construction monitoring would
qualitatively assess the following ecosystem indicators as compared to adjacent native vegetation
conditions:
• bare ground percentage, including rocks, woody debris, biotic soils, and leaf litter
• plant cover percentages, vegetation composition, and soil stability
• noxious weed species (new and existing populations)
5.2 Noxious Weeds Management
Management and monitoring activities within reclaimed Project areas are expected to require ongoing
and integrated noxious weed control. Monitoring weed occurrences would primarily involve inspections
of previously treated areas but would also inspect other areas to minimize the spread and
establishment of weed species. Monitoring would occur 10-14 days after the implementation of weed
control measures to determine the efficacy of control methods. As required, additional control
measures would be conducted by the reclamation contractor to manage noxious weed occurrences.
Guidelines for monitoring and integrated weed management would include the following:
• Monitoring would be conducted using a qualitative, visual assessment of the previously
implemented management control(s) efficacy.
• At each detected noxious weed occurrence, surveyors would record species, relative
population size, and location (including GPS coordinates).
• Additional control measures would be implemented to control existing weed occurrences and
minimize their potential to spread into reclaimed Project areas.
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Vegetation Management Plan
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5.3 Reporting and Remedial Actions
The reclamation contractor would submit ongoing weed treatment reports (i.e., herbicide application
records) to the Garfield County vegetation manager after each weed treatment event. These reports
would include the control method, amount and type of herbicide used (if any), date of application,
treated acreage, weed species treated, GPS location of treated area(s), and other pertinent
information. Application forms would be submitted within a month of treatment.
Other maintenance activities would consist of the installation, replacement, or removal of erosion
control measures, as necessary, throughout the maintenance, monitoring, and reporting period. All
plastic silt fence, straw wattles, and rock socks would need to be replaced intermittently and removed
after reclamation is complete. Plastic becomes litter and a hazard to wildlife even if the item is
marketed as “UV degradable.” It is therefore recommended that fully biodegradable stormwater control
measures are used to avoid the potential hazard to wildlife. All non-biodegradable materials that are
not permanent would need to be removed completely before reclamation monitoring is complete.
Seasonal precipitation and related runoff could affect overall plant cover within and adjacent to
drainage features. With the installation of erosion control devices (e.g., silt fencing, straw wattles) at
reclamation sites, seasonal runoff events are not anticipated to reduce the potential to meet the
reclamation success criteria. However, if reclamation progress is being affected by runoff and erosion,
then remedial actions would be implemented as necessary to address the issue(s). These actions
would consist of recontouring, additional erosion control measures, and/or supplementary seeding.
Drought conditions caused by low precipitation and prolonged unseasonal temperatures could
negatively affect reclamation and revegetation progress. Drought could result in reduced plant
regrowth and establishment, higher plant mortality, or an increased potential for noxious weed
infestations. Remedial measures for prolonged drought would include strategic reseeding prior to
precipitation events; extension of the maintenance, monitoring, and reporting period; and potential
adjustment of the performance success criteria for drought conditions. These and additional remedial
measures would be implemented by the reclamation contractor and approved by Garfield County
vegetation manager (see Table 4).
Table 4. Project Contacts
Location Title Name Email Phone
AES
Louisville Project Manager Joshua Mayer joshua.mayer@aes.com O: 720-514-2957
Louisville EPC Project Manager Jason Owens jason.owens@aes.com M: 303-883-5207
HDR
Denver Biologist Andrew Phillips andrew.phillips@hdrinc.com O: 719-272-8816
Denver Project Manager Melinda Lee Melinda.leer@hdrinc.com O: 303-524-8376
Regulatory Agencies
Garfield County Vegetation Manager Steve Anthony santhony@garfield-
county.com O: 970-945-1377
NRCS Rangeland Specialist Christine Prins christine.prins@usda.gov O: 970-361-3776
NRCS Resource
Conservationist Allison Hearne Allison.Hearne@usda.gov O: 970-529-8364
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
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6 References
CDA 2021 Colorado Department of Agriculture (CDA). 2021. Noxious Weed Species ID. Available
online: <https://ag.colorado.gov/conservation/noxious-weeds/species-id#d>.
Bokan et al.
2021
S. Bokan, K. Crumbaker, and G. Beck. (2021). Identification and Management of Kochia
and Russian Thistle. Colorado State University Extension. Available online:
<https://extension.colostate.edu/docs/pubs/natres/06314.pdf>.
GCVM 2016 Garfield County Vegetation Management (GCVM). 2016. Garfield County Noxious Weed
Management Plan. Prepared by GCWM and the Garfield County Weed Advisory Board.
Available online: <https://www.garfield-county.com/vegetation-
management/filesgcco/sites/29/2019/11/Garfield-County-Noxious-Weed-Management-
Plan-Adopted-Feb-2016.pdf>.
NRCS 2021 Personal Communication between Christine Prins (Rangeland Specialist, NRCS), Allison
Hearne (Resource Conservationist, NRCS) and Andrew Phillips (HDR, Biologist)
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
A Control Methods for Project Weed Species
AES High Mesa Project | Garfield County, Colorado
Vegetation Management Plan
March 2022 | A-1
Table A.1. Control Methods for Project Weed Species
Species CDA
Rank
Recommended Control Methods 1 Control Methods ^
Mechanical Chemical Cultural
Downy
brome
(Bromus
tectorum)
C No Yes Yes Mechanical: Mechanical methods are best for small infestations. Mowing is not recommended as it leaves
roots intact, stimulates flower production, disperses seeds, and can expand the size of the infested area.
Chemical: Herbicides are effective but are often impractical for larger populations and can affect grasses
that would otherwise compete with downy brome.
Cultural: Revegetating with a perennial grass promotes natural competition and effective control.
Recommended Approach: Integrated management using cultural and chemical control methods.
Musk thistle
(Carduus
nutans)
B Yes Yes Yes
Mechanical: Tilling, hoeing, and digging are effective for occurrences smaller than about 0.5 acre. Mowing,
chopping, and deadheading requires consecutive years of treatment and often stimulates more flower
production. All flower buds and heads must be collected, bagged, and destroyed as seeds can mature and
germinate if left on the ground.
Chemical: Herbicide applied on spring rosettes, early bolting growth stages, or on fall rosettes.
Cultural: Minimizing soil disturbances, revegetating with competitive grasses, and strategic avoidance of
disturbances on mesic areas.
Recommended Approach: Mechanical, cultural, and spot chemical control methods.
Russian
thistle
(Salsola
tragus)
No
Rank
Yes Yes Yes Mechanical: Pulling or light tillage during early growth can be effective for small infestations. Mowing must
occur just before blooming to prevent regrowth.
Chemical: Most effective if applied in the spring during early growing.
Cultural: Promoting competition using native vegetation.
Recommended Approach: Mechanical, cultural, and chemical control methods.
^ Annual treatments for four years post-construction
Note 1 – Biological controls are not proposed or recommended for the weeds in the Project area
Source: CDA 2021, Bokan et al. 2021, GCVM 2016
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 29
Please see the following pages for the Traffic Study prepared by HDR Consulting, updated in October
2021, addressing the existing road system’s and driveway’s compliance to the Road Standards and
Section 7-107. All on-site driveway and interior road improvements are documented in the civil plan
sets in Section B2.
TRAFFIC STUDY
Section B5
_________________________________________________________________________________________________________
_________________________________________________________________________________________________________
1
Traffic Impact Letter
Date: Tuesday, October 4, 2021
Project: Garfield County Solar Projects
To: Garfield County
From: John Seyer, HDR
Subject: High Mesa Site Traffic Impact Review
____________________________________________________________________________
1 Introduction
In partial fulfillment of the Garfield County Land Use Change permitting requirements, HDR has
completed this Traffic Impact Report for the proposed High Mesa solar development site located
near Parachute, Colorado in Garfield County. This report was developed to provide traffic-related
information and to identify potential impacts to the roadway network adjacent to the project. The
following information is included in this report:
• Project Location, Components, and Construction Schedule
• Designated Travel Route
• Daily Vehicle Trip Generation
• Conclusions
2 Project Location, Components, and Construction Schedule
Location
The High Mesa site is located approximately four miles south of the Town of Parachute, Colorado
at 1691 County Road 300 (Parcel ID 2409-351-00-136). This parcel is approximately 340 acres
with a project size of 84 acres. The location of the site is shown in Figure 1.
Components
The High Mesa site will house a 10-megawatt solar facility coupled with lithium ion battery storage.
There will be four battery storage units, each of which is anticipated to be approximately the size
of an industrial shipping container. HVAC units will be included and used for cooling.
Schedule
It is anticipated that the Land Use Change Permit will be issued by Garfield County in or before
February 2022. Accordingly, the construction mobilization date is tentatively May 1st, 2022. Based
on this mobilization date, the preliminary construction schedule is:
Land Use Change Permit Schedule – High Mesa Start Date End Date
Component Delivery 5/1/2022 9/1/2022
Perimeter Fence Installation 7/1/2022 9/1/2022
Solar Panel Foundation Installation 7/1/2022 9/1/2022
Solar Panel Installation 7/15/2022 10/1/2022
Transformer and Inverter Installation 7/15/2022 10/1/2022
_________________________________________________________________________________________________________________________________________________
_________________________________________________________________________________________________________________________________________________
2
Figure 1: Project Location and Designated Access Route
High Mesa
Solar Site
Access Route
_________________________________________________________________________________________________________
_________________________________________________________________________________________________________
3
3 Designated Access Route
The designated access route for the High Mesa site is: I-70 to Exit 72 (West Parachute); south on
Old US Highway 6 (2.5 miles); east on Stone Quarry Road (1.9 miles); then east on Richardson
Road (0.5 miles). This route is illustrated in Figure 1. A brief description of the road segments
along the access route is provided below.
• Old US Highway 6: This 2.5-mile segment of Old US Highway 6 is a two-lane (one per
direction) roadway extending from a dumbbell interchange with I-70 to Stone Quarry Road
to the southwest. The posted speed limit along this segment is 50 miles per hour. This
roadway segment is asphalt-paved and has a travel width of approximately 24 feet with
shoulder widths from zero to 12 feet. The pavement appears to be in good condition.
• Stone Quarry Road: The 1.9-mile segment of Stone Quarry Road included in the access
route is a two-lane road with a posted speed limit of 35 miles per hour. At its junction with
Old US Highway 6, Stone Quarry Road crosses active train tracks. The travel width along
this segment is approximately 24 feet with unpaved shoulders that range from zero to 12
feet in width. Weight limits are posted at the north end of this segment: 54,000 pounds for
3-axle vehicles and 80,000 pounds for 5-axle vehicles. Overweight vehicles are allowed
by permit only. Striping condition varies. According to County Road and Bridge, this road
is reaching its useful life because the pavement is beginning to deteriorate. The County
intends to perform a mill and overlay to rehabilitate the road surface sometime within the
next few years.
• Richardson Road: One-half mile west of the High Mesa solar site, vehicles will bear off
to the right onto Richardson Road. This 0.5-mile segment has a paved surface and a
posted speed limit of 15 miles per hour. The roadway width ranges from 18 to 24 feet.
According to County Road and Bridge, similar to Stone Quarry Road, this road is reaching
its useful life because the pavement is beginning to deteriorate. The County intends to
perform a mill and overlay to rehabilitate the road surface sometime within the next few
years.
The designated access route for the High Mesa site after construction will be the same access
route described above that will be used during construction. It is understood that access permits
for the temporary construction access and permanent access will be obtained from the County as
required and that an Access Permit from CDOT is not required for use of the I-70 ramps or Old
US Highway 6.
According to the County’s latest traffic volumes, Stone Quarry Road carries 505 vehicles per day
and Richardson Road carries 205 vehicles per day. Per Table 7-107 of the Garfield County Land
Use and Development Code (LUDC), Stone Quarry Road would be classified as a Minor Collector
and Richardson Road would be classified as a Secondary Access.
_________________________________________________________________________________________________________
_________________________________________________________________________________________________________
4
4 Daily Vehicle Trip Generation
The project can be divided into three phases: Delivery, Installation, and Maintenance/Operations.
The estimated maximum and average vehicle trips per day by vehicle type and project phase are
summarized in Table 1.
Table 1: Daily Vehicle Trip Generation
Project Phase
(Time Period) Vehicle Type Estimated Gross
Vehicle Weight
Vehicles
per Day
Vehicle Trips
per Day
Delivery
[3 weeks]
Conex Containers and
Delivery Trucks 30,000-50,000 lbs. 2-4 4-8
Equipment Hauling
Trucks 20,000-40,000 lbs. 1-2 2-4
Maximum: 12
Average: 6
Installation
[Approx. 10 months]
Passenger Vehicles 2,000-10,000 lbs. 20-30 40-60
Fuel Truck 20,000-30,000 lbs. 1 2
Material Delivery Truck 20,000-30,000 lbs. 1 2
Maximum: 64
Average: 44
Maintenance
and Operations
[Ongoing]
Utility Vehicle 2,000-10,000 lbs. 1 per month
or less 0-1
Maximum: 1
Average: 0
As shown in Table 1, most heavy vehicle traffic is expected over the three-week delivery period.
This traffic will include delivery of 53 Conex containers. Other equipment and components will
account for approximately 50 deliveries spread over the 6-8-month installation period. Most of this
traffic will travel to and from the project site between 9:30AM-12:00PM and 1:30PM-4:00PM so
as to not affect peak hour traffic. Impacts to operations during peak demand periods (7:00AM-
9:00AM and 4:00PM-6:00PM) are not expected to be significant.
Most passenger vehicle traffic will be generated during the 6-8-month installation period. This will
primarily be site worker and project management traffic. It is expected that during peak installation
there will be a maximum of 30 employees at the site per day, equating to a maximum of 60 light-
duty vehicle trips per day. Ongoing maintenance/operations are expected to generate one trip per
month or less.
Per Table 7-107 of the Garfield County LUDC, the High Mesa access driveway is designated as
a “Semi Primitive” road, as its Operational Average Daily Traffic is anticipated to be up to 77
vehicles per day. Adding the anticipated daily traffic demand to the existing traffic volumes along
Stone Quarry Road and Richardson Road noted in the previous section will not exceed the volume
threshold of each roadway classification; Stone Quarry Road will remain a Minor Collector and
Richardson Road will remain a Secondary Access. All standards within Table 7-107 are reflected
in the design documents submitted to Garfield County.
_________________________________________________________________________________________________________
_________________________________________________________________________________________________________
5
Per County Road and Bridge, the County intends to rehabilitate the roadway surfaces of Stone
Quarry Road and Richardson Road within the next few years. After reviewing the anticipated
loading from the traffic projections in Table 1 with Road and Bridge, it was determined that
added traffic from High Mesa development would not likely cause enough damage to accelerate
the need for these repairs, so it’s not anticipated that improvements would need to be made to
these two roadways at this time.
_________________________________________________________________________________________________________
_________________________________________________________________________________________________________
6
5 Conclusions
1. Mobilization is expected on May 1st, 2022. Conex containers will be delivered over a three-
week period, then the installation period is expected to last for approximately 6-8 months
and will generally entail infrequent deliveries of other equipment and components.
2. Over the three-week delivery period, it is expected that approximately 55 Conex container
deliveries will be made, along with some initial equipment. This is estimated to result in a
maximum of six deliveries, or 12 trips, per day. Most of these trips will be made outside of
the peak periods so as to avoid impacts to daily traffic operations.
3. Over the 6-8-month installation period, it is expected that a maximum of 30 employees will
be on-site each day. This is estimated to result in between 40 and 60 passenger vehicle
trips per day, all of which are expected to be in light-duty vehicles.
4. Material delivery will be spread throughout the 6-8-month installation period, with a total
of approximately 50 deliveries. This equates to one or fewer deliveries, or up to two vehicle
trips, per day.
5. Ongoing maintenance/operations during the solar development’s lifespan are expected to
result in one utility vehicle trip per month or less.
6. Per Table 7-107 of the Garfield County Land Use and Development Code, the site access
driveway is designated as a “Semi Primitive” road with estimated daily traffic during
maintenance and operations up to 77 vehicles per day. The classifications of Stone Quarry
Road and Richardson Road will remain as they are today. County Road and Bridge
anticipates that the projected traffic loading detailed in Table 1 of this TIA will not require
improvements to these two roadways ahead of the County’s planned pavement
rehabilitation in the next few years. All standards within Table 7-107 are reflected in all
documents submitted to the County.
7. As proposed, the High Mesa solar development delivery and installation phases are not
anticipated to create adverse impacts to traffic operations along public roadways in
Garfield County. Based on the anticipated vehicle types and weights, adverse impacts to
pavement along Garfield County roadways are not expected.
We trust that this traffic impact letter for the High Mesa solar project is acceptable and complete.
Please contact me at john.seyer@hdrinc.com or at 970.416.4407 if you have questions or need
clarification on anything in this letter.
Sincerely,
John M. Seyer, PE, PTOE
Traffic Engineer
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 30
Access and Roadways (7-107)
The designated access route as shown in the attached Traffic Memo for the High Mesa site will be used
both during and after construction and is granted to AES High Mesa Solar, LLC, via the terms in the
Memo of Purchase Option provided in Section A3 (see part D).
It is understood that access permits for the temporary construction access and permanent access will be
obtained from the County as required and that an Access Permit from CDOT is not required for use of
the I-70 ramps or Old US Highway 6. Also, as proposed, the High Mesa solar development delivery,
installation and operation phases are not anticipated to create adverse impacts to traffic operations or to
the pavement and roadway surfaces along public roadways in Garfield County.
Please refer to Section B5 - Traffic Study for further details on road classifications and impact analysis.
The Point of Interconnection (POI) to the Holy Cross distribution system for the Project is located on the
property along the recently upgraded three phase power line pathway and easement that provides service
to the Klebold’s residence, which had previously only been single phase until HCE moved forward in
Summer 2021 with the upgrades to accommodate the Project. The Project will no longer have to traverse
the ravine to the east towards the originally intended POI near the High Mesa Compressor Station;
therefore, no additional easements are required to support the Project.
ACCESS PERMITS, EASEMENTS, AND ACCESS ROADWAY DETAILS
Section B6
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 31
Improvements Agreement Waiver
Provided that the High Mesa Solar project is not seeking or requiring public improvements in services as
part of its development, AES respectfully requests a waiver on the Improvements Agreement described
in Article 4-203.K.
IMPROVEMENTS AGREEMENT
Section B7
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 32
Development Agreement Waiver
Provided that the High Mesa Solar project will be built in one continuous phase beginning as soon as
May 1, 2022 but extending through 2022 with an expected completion no later than December 31st,
2022, AES respectfully requests a waiver on the Development Agreement described in Article 4-203.J.
DEVELOPMENT AGREEMENT
Section B8
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 33
Wastewater Infrastructure Waiver
The planned solar facility will be unmanned during operation with all site monitoring during operations
being managed remotely. Scheduled visits for landscaping or equipment maintenance are expected to be
less than 6 times per year unless more visits are necessary to replace faulty equipment. As such and with
no permanent employees onsite, there is no need for permanent wastewater collection or treatment
onsite during the operational phase of the facility as it will not generate wastewater. A waiver from the
wastewater system requirements of either a public sewer system extension or onsite wastewater
treatment system as detailed in Sec 7-105. B is hereby requested.
For the construction period, AES has secured a Will Serve letter from Redi Services, LLC, for
wastewater services for personnel. For porta-johns, typically one facility is provided for every ten site
workers.
See the following pages for the Will Serve letter.
WASTEWATER PLAN
Section B9
9/16/2021
Page 1 of 1 Redi Services, LLC
2143 Airport Road
Rifle, CO 81650
970-625-0233
AES Clean Energy,
Will Serve Letter for High Mesa Solar, LLC. Located at 1691 County Road 300 Parachute Colorado 81635
To whom it may Concern,
Redi Services, LLC will provide Waste Management services as needed for as long as required for the project described
as High Mesa Solar LLC and located at 1691 County Road 300 Parachute Colorado 81635. Redi Services has sufficient
personnel and resources to serve this project and is located within Garfield County at 2143 Airport Road Rifle, Colorado
81650. All waste streams created would be disposed of at Garfield County Landfill Located at 0075 Co Rd 246, Rifle, CO
81650. If you have any questions, please feel free to contact me.
Respectfully,
Craig Abernathy
Regional Director - Western Colorado, Wyoming, Utah, Idaho
REDI SERVICES since 1982
Safety and excellence in industrial services
2143 Airport Rd, Rifle, CO 81650
t (970) 625-0233 | c (970) 309-1234 | f (970) 625-0232
e cabernathy@RediUSA.com
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 34
Water Distribution System Waiver
The planned solar facility will be unmanned during operations with all monitoring being managed
remotely. As such and with no permanent employees onsite, there is no need for permanent water
distribution service to the facility. Any needs for water during construction (e.g. dust suppression) will
be served by trucking in water. If the operator decides to clean the solar arrays, de-ionized water will be
required and will be trucked in for that purpose. A waiver from the distribution system requirements as
detailed in Sec. 7-105. A is hereby requested.
For the construction period, AES has secured a Will Serve letter from Rifle Creek Pure Water for
requisite water supply. Water supply amounts and frequencies for construction needs is still to be
determined by the final contractor.
See the following pages for the Will Serve letter.
WATER SUPPLY PLAN
Section B10
From:Jason Owens
To:Joshua Mayer
Subject:FW: Service Confirmation Email from Rifle Creek Pure Water
Date:Friday, October 8, 2021 1:07:29 PM
Here’s the Will service email from Rifle Creek Pure Water in Rifle.
Let me know if this is what you need for Garfield County. JO
From: Jeremy Young <rcpw2018@gmail.com>
Sent: Friday, October 8, 2021 12:09 PM
To: Jason Owens <jason.owens@aes.com>
Subject: Service Confirmation Email from Rifle Creek Pure Water
USE CAUTION: External Sender
Jason,
Rifle Creek Pure Water services all areas from around Grand Junction, Co to Edwards, CO, potable
and non-potable needs. NOTE: all water hauled IS Domestic Water.
this includes:
Peace Bear Ranch
2714 CO RD 331
Silt, CO 81652
and
High Mesa Site
1691 CO RD 300
Parachute, CO 81635
Thank You!
~Jeremy
Rifle Creek Pure Water
PO Box 1392
Rifle, CO 81650
(970) 319-6622
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 35
LUDC Article 7 Standards 1, 2 & 3 and 7-1101
7-101: Zone District Use Regulations: The Land Use Change for High Mesa solar facility will comply
with Article 3, Zoning, and any applicable zone district use restrictions and regulations
7-102: Comprehensive Plan and Intergovernmental Agreements: The Land Use Change is in general
conformance with the Garfield County Comprehensive Plan 2030 (GCCP) and, to the best of AES’
knowledge, complies with any applicable intergovernmental agreement. The GCCP encourages the
development of renewable energy generation resources for the benefit of individuals, communities and
the County as a whole. The proposed site is outside the Urban Growth Area for Parachute CO, but
within the designated 3-mile influence area for Parachute, and the proposed use is compatible with the
low-density residential (10+ac) future use designation. In terms of scale, this use is low in profile. Solar
energy generation is, by nature, a passive use of energy generation technology and is consequently low
in intensity in comparison to other uses. The facility will not be a significant source
of dust, glare, noise, air or light pollution, and will not generate heavy traffic over its expected lifetime.
As such the proposed use, at a significant distance away from the rural residences nearby, is a good fit
on this property which is also bordered by oil and gas activities and vacant land.
Please see Appendix C7 for the SolarForge Glare Study that AES performed for the site indicating that
there are no anticipated incidences of “yellow” or “green” glare from observational points to the Project.
7-104: Compatibility: Solar farms are passive facilities that operate in silence, emissions-free, and
absent of daily traffic. Provided that the property siting the Project is in an area of high-density oil and
gas operations, including on the property itself, the proposed facility would be keeping in line with the
natural resource focus of land use in the area. Furthermore, given its location several miles from the
Town of Parachute on elevated land above the valley floor, there are few nearby points from which the
project is in public view.
7-104: Source of Water: The proposed solar facility will not require water for operation. Any water
required for construction or maintenance will be supplied by a licensed water hauler. Please refer to the
Will Serve letters provided in Sections B9 and B10 from Redi Services, LLC and Rifle Creek Pure
Water.
7-105: Central Water Distribution and Wastewater Systems: The proposed use, as an unmanned
facility, will not require central water distribution or wastewater systems.
7-106: Public Utilities: Proximity to electrical distribution infrastructure is the prime factor in selecting
this site for the proposed use. There is a three-phase line operated by Holy Cross Electric approximately
NARRATIVE RESPONSE TO ARTICLE 7 STANDARDS 1, 2, 3 AND SECTION 7-1101
Section B11
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AES High Mesa Solar – Garfield County 36
100 feet to the west of the proposed solar array areas to which the Project will interconnect. The utility
will draft, and the landowner will execute, any necessary easements for the installation and maintenance
of utility equipment required for the interconnection of the solar facilities to the power grid, such as
power lines and associated equipment. It is expected that the utility transformers and other similar
equipment will be mounted above ground on concrete pads, and that any power lines connecting the
facility to the adjacent power line will be underground. Such utility easements will not be dedicated to
the public. There are no prior legal encumbrances on the parcel that would conflict with the likely path
of such easements.
Please see Appendix C8 for a Letter of Attestation from Holy Cross Energy and confirmation of
interconnection capability to their distribution system.
7-107: Access and Roadways: The subject parcel already has legal access to the proposed array areas
from I-70, Old US Highway 6, Stone Quarry Road, and Richardson Road which will adequately and
safely serve the proposed use. Improvements to the above-mentioned roads will not be necessary and
traffic generated by the construction or operation of the facility is not anticipated to cause any significant
impacts to public rights-of-way.
Please refer to Section B5 for the Traffic Study detailing this further.
7-108: Use of Land Subject to Natural Hazards: AES has conducted desktop analysis and various
studies on the land and does not believe the designated solar array areas to be subject to significant risk
from natural hazards such as floods, avalanches, landslides, or earthquakes.
7-109: Fire Protection: All equipment installed at the proposed solar facility will be new, of good
quality, UL-listed, and will meet all established testing and safety parameters, including compliance
with NFPA 855 and UL 9540. The solar facility will be primarily constructed from non-combustible
materials such as glass, aluminum and steel. Electrical fires at solar generation facilities are rare and
there are safeguards built into the system design to shut down operations should dangerous conditions be
detected. Most fire concern with solar installations of this nature comes from the possibility of the
installation being impacted by brush fires that originate elsewhere but shift to threaten the equipment.
Mitigation of fire danger will be achieved by keeping the vegetation under the arrays and within the
perimeter fence trimmed and ensuring regular maintenance of the solar generation equipment. Sufficient
space of a minimum 15 ft. will be left between the solar array perimeter and the perimeter fence to allow
for access in case of fire, and the dedicated array driveways will be able to safely accommodate fire-
fighting trucks and equipment. The local fire protection district will be provided with the gate code for
access should it be required, and AES will follow the recommendations of district staff after their review
of this application.
Furthermore, AES leverages our 24/7 Remote Operations Center (ROC) as our “supervising station”.
The ROC uses a high security communications link to our Data Acquisition System (DAS) to monitor
sites and receive alarms. Alarms related to fire suppression systems, such as high internal air
temperature and impairment or discharge of fire suppression elements, are prioritized as “Critical”.
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 37
Upon receipt of a Critical alarm, the ROC will immediately contact the Project’s respective field
services technicians via phone call, regardless of the time of day. The technicians will be equipped with
local emergency contact information through prior consultation with local first responders and, upon
receiving notification from the ROC about a fire suppression system-related alarm, will notify those
local contacts.
Please see Appendix C9 for AES’ Fire Risk Assessment report for the proposed battery storage
configuration for AES High Mesa Solar.
Prior to operation, AES will also provide first responders with a site orientation and presentation on the
facility and provide links to third party resources should further training on firefighting around electrical
system, including PV arrays, be desired.
See Appendix C12 for the standard Operations and Maintenance Schedule planned for AES’ facilities,
detailing frequencies with which systems, componentry, and vegetation need be inspected and managed
to ensure optimal performance and reduced likelihood of system failure or fire hazard.
7-201: Agricultural Lands: There is no known adverse effects of solar installations on adjacent or
nearby lands. In fact, it is possible to conduct agricultural activities on the same footprint concurrently
with solar operations, although that is not the intention for the Project. The system operator will follow
all county regulations, if applicable, regarding the control of domestic animals; maintenance of the
perimeter fence; and road maintenance and dust control.
It is not believed that this project has any nexus with the standards for irrigation ditches described in 7-
201.E, most specifically since none of the ditches on the property belong to the jurisdiction of a formal
ditch company, rather are private in nature and belong to the Klebold family. Still, per the conditions
defined in the Purchase Agreement Section 20. (excerpt follows) between AES and the Klebolds, a
minimum of 20’ setback will be maintained along the full length of existing ditches and access will not
be impeded. In the only section where the ditch is to be encompassed within the perimeter fence, the
ditch will be piped to avoid complications for maintenance and access. All crossings will be to code and
not impede hydraulic flow characteristics.
See the Site Plan in Section B2 for further detail.
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 38
“
”
If this excerpt from the executed Option to Purchase Agreement is not proof enough of landowner
consent, then AES can provide a specific letter at the County’s request.
7-202: Wildlife Habitat Areas:
In all, 11 federally listed species under the ESA and 7 state special status species were identified with the
potential to occur, at least seasonally, in the Project area. Of the federally listed species, suitable habitat
for the Colorado Hookless Cactus (CHC) occurs within the Project area. A focused survey was conducted
in the Project area during the CHC flowering season (May 1 to July 1) on May 25, 2021. The survey did
not detect the federally protected cactus species; therefore, the CHC is unlikely to occur in the Project area
or be impacted by Project activities. None of the other federal listed species would be impacted as a result
of the Project.
Habitat for two state species of special concern (midget faded rattlesnake and northern leopard frog) was
noted to occur in the Project area. However, these two species are unlikely to occur in the Project area or
be impacted by Project activities because the available habitat is of lower quality and/or would only be
used for transient movement. Foraging habitat for the peregrine falcon and Townsend’s big-eared bat was
also noted to occur within the Project area. Bald eagle nesting sites occur in the vicinity, but not within or
close enough to the Project area to result in effects to nesting eagles. However, there is suitable nesting
habitat for other raptors species and migratory birds. In order to avoid violating federal law (BGEPA and
MBTA), nesting surveys are recommended prior to Project activities if construction is scheduled to occur
inside of the nesting season (February 15–July 15 for raptors and May 1–August 31 for other migratory
birds) (CPW 2020b).
The Project area contains habitat for big game species, including mule deer (Odocoileus hemionus) and
Rocky Mountain elk (Cervus canadensis). Specifically, the Project area contains severe winter range and
winter concentration area for elk and mule deer. In order to minimize disturbances on elk and mule deer,
no Project activities would occur between December 1 to April 30 (CPW 2021e). Exceptions to this time
limitation for construction or related Project activities would not be permitted for this Project (CPW
2021f). CPW would require that off-site mitigation occur at a 1:1 ratio to offset the loss of functional
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 39
habitat due to the Project (CPW 2021e; CPW 2021f). As the Project proceeds, AES would continue to
coordinate with CPW regarding an off-site mitigation strategy in an effort to identify a habitat
improvement project(s) that would aid local wildlife (CPW 2021f).
The Project is not expected to result in the death of individual special status species (federal or state listed)
but would result in the loss of some habitat, primarily for big game species. Therefore, the Project would
require three key impact minimization measures for protecting big game wildlife, including: (1) wildlife
exclusion fencing, (2) seasonal construction limitations, and (3) mitigation for functional habitat loss.
Please see Appendix C2 for the complete Biological Resources report detailing USFWS and CPW
consultations and analysis, including the USFWS IPaC report, site photos, and vegetation and wildlife
habitat maps.
Please also refer to Section B4 for the revegetation plan detailing an appropriate seed mix and application
rate recommended for the Project’s location from the Natural Resources Conservation Service (NRCS),
featuring mostly Western wheatgrass, Indian rice grass, Bluebunch wheatgrass, and Galleta grass, among
others.
7-203: Protection of Waterbodies: The facility has been designed to avoid impacts on wetland areas in the
Project area. Please refer to the included site plans and its 35’ setback recommendations. The construction
of the solar array will not require the removal of vegetation within the setback area, or the permanent
alteration of the current surface drainage characteristics. There will be no permanent storage of hazardous
chemicals or road salt within the Project area.
Please see Appendix C1 for a formal wetland delineation of the site.
7-204: Drainage and Erosion: As detailed in the Stormwater Memo and Management Plan, the
installation of the solar arrays will disturb much of the project footprint during construction prior to
revegetation efforts and will produce 40,370 sf (0.93 acres) of impervious area which covers 1.23% of
the project site. The project will be subject to the CDPHE NPDES permit requirements, an application for
which was submitted November 8th, 2021. Onsite drainage patterns will be maintained with exception to
minor grading related to proposed gravel roads, therefore a Drainage Report is not required per county
standards. Stormwater Management (treatment & detention) are not required because the proposed
impervious area is not expected to significantly alter stormwater quality and quantity and existing
drainage patterns are maintained. Using a grass seed mix to restore all areas of disturbance, stormwater
quality will be improved through a native seed mix. The mix will also decrease the quantity of stormwater
runoff previously experienced on site. The proposed access road will require the installation of culverts.
Initial sizing has been provided and will be refined as the site design develops.
For further details, please see Section B2 for the Site Plan and page C1-06 for the Drainage and Erosion
plan. Also reference Appendix C6 f or the Stormwater Memo and Appendix C6a for the receipt of
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 40
submission to CDPHE. The full Stormwater Management Plan submitted to the CDPHE will be sent to
the County as a separate addendum given its size.
7-205: Environmental Quality: The completed facility is expected to have zero negative impact to air
quality, and no permanent storage of hazardous materials will occur onsite.
7-206: Wildfire Hazards: The subject property is designated as “Moderate to High” fire danger
according to the Wildland Fire Susceptibility provided by Garfield County. That said, the facility will
consist primary of noncombustible materials such as steel, glass and aluminum and vegetation will be
maintained to reduce potential fuels and associated fire danger, in addition to providing setbacks of at
least 15’ between perimeter fencing and array locations and the siting of gravel interior access roads
near key equipment as another form of fire break. The battery storage containers include their own fire
suppression equipment as detailed in Appendix C9.
Please see the attached Wildland Fire Susceptibility Index map from Garfield County in Appendix C10.
7-207: Natural and Geologic Hazards: The proposed site is not known to be marked as a Hazard Area
for avalanche, landslide, or rockfall. Construction is not proposed in an alluvial fan area or on slopes of
20% gradient or greater, or otherwise unstable slopes, nor within any designated mudflow areas or over
any known faults. A geotechnical investigation of the area revealed a low to moderate potential for
corrosive soils to be present onsite. All concrete slab and driven steel foundations will be designed with
sufficient protection to allow the facility to meet its design life expectations according to the native
soils’ corrosive and/or expansive properties as detailed in the geotechnical report.
Please see Appendix C11 for the Geotechnical Engineering report prepared by Terracon.
7-208: Reclamation: After construction, all disturbed areas within the site fence line will be over-seeded
with the proscribed seed mix consisting of native, low-growth plant species and established in
accordance with County standards. No major changes to the existing site topography are proposed.
Please refer to the Site Plan in section B2 and the comprehensive Vegetation Management Plan in
section B4 for more details.
7-301: Compatible Design: Project area is zoned Rural, with Rural zoning on the North, South and West
adjacent sides with Public Lands adjoining the Easterly sides. The proposed use is considered to be low-
impact both with regard to the land on the subject parcel and to neighboring parcels. Outside of the
relatively short construction period, where some noise, fumes, and dust can be expected from the
operation of construction equipment, the facility will not be a significant source of dust, odors, gas,
fumes or glare throughout its operational life. The solar facility will be sited at a minimum of 100 ft
setback from property lines in compliance with its categorization as an Industrial Use per 7-1001 B.
Please see Section B-12 - Impact Analysis for discussion of glare potential at the project location.
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 41
7-302: Off-Street Parking and Loading Standards: The proposed use of a Solar Energy System – Large
is not found in Table 7-302.A. As an unmanned facility, permanent parking is not necessary for this use.
Designated areas for parking will be identified during construction, and no street or right-of-way
shoulder parking will be permitted either during the construction or operational phases of the project.
Site design is proposed to allow for trucks delivering equipment and construction materials to pull
completely off Richardson Road before unloading. Permanent loading bays are not appropriate for this
use as there is no building proposed that could accommodate loading bays, and very few additional
deliveries of equipment or materials are anticipated during the operational life of the facility.
7-303: Landscaping Standards: Applicant has prepared a vegetation management plan for all disturbed
areas within the solar array fence lines, with recommendations for the planting and establishment of
ground cover depending on the season in which construction is completed. All species will be selected
as native, drought-tolerant grass species with a relatively low growth profile, to minimize the potential
for shading of the solar arrays and to minimize susceptibility to fire danger. The land in question is dry,
with poor soils, significant sun exposure and very little rainfall. As such, the planting of additional trees
or shrubs is not recommended in keeping with 7-303.C, where landscaping must be consistent with the
unique ecosystem and specific environment local to the development. There is very little likelihood that
such larger vegetation would be able to establish itself or thrive in such an environment, as shown by the
sparse vegetation currently present on the parcel.
Please see Section B4 for the Vegetation Management plan.
7-304: Lighting Standards: Perimeter or security lighting is not proposed for this facility. It is likely that
each equipment pad will feature a single task light with a manual switch, to be used if maintenance or
repair to the electrical equipment is required to take place outside of daylight hours. Such task lighting
will be downcast to illuminate the electrical equipment area and will not be oriented toward neighboring
properties.
7-305: Snow Storage Standards: Given that the facility will be unmanned, with no permanent parking
and a trip frequency of less than 1 vehicle per month during operations, there is no need for snow
storage at this facility.
7-306: Trail and Walkway Standards: Due to the remote location of the proposed facility far away from
shopping parks, schools, parks, trails and greenbelts, the inclusion of trails, walkways or other similar
improvements as part of this development is not considered to be recommended or necessary.
7-1101: Solar Energy Systems: There will be signage installed at the gate and at regular intervals along
the perimeter fence of each array, warning of electrical shock hazard, as shown on the site plans and
required by 7-1101.A. The remainder of the standards discussed in 7-1101.B are for Accessory Solar
Energy Systems and do not apply to this application
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 42
Impact Analysis to Items in Section 4-203G
Adjacent Land Use
Adjacent lands are primarily used for oil and gas extraction to the east and south, otherwise there are
few other residential properties in proximity to the project area, just a couple to the southwest across the
unnamed ravine and largely out of site of the Project. BLM exists to the northeast and east and some
agricultural lands are situated to the north and will not be impacted in any way nor have observation of
the Project.
Site Features
The property is approximately 340.01 acres and consists of two primary areas situated on a flat top
plateau. The northern area is used for crop growth and residence, in addition to hosting two oil/gas pad
infrastructure areas. The southern area is vacant and wooded. Away from the project area to the east, a
ravine features prominently as a steep, vacant, and wooded area that contains underground natural gas
lines. The Project will be sited on the flat portions of the property to avoid steep areas and any need for
significant grading, as well as water features such as ditches or ponds. Floodplains are situated at much
lower elevations below the property and far from the Project area.
Please see Appendix C2 – Biological Resource report for more in depth description of site features.
Soil Characteristics
See the summary of soils in the Project area as excerpted from the Biological Resources Report. There are
no hydric soils within the project area or areas considered Prime Farmland without the aid of irrigation,
however, soil disturbances would be minimized to the extent possible and Best Management Practices
employed to minimize soil erosion/transport and control the spread of non-native plant species. Soils types
found on site are not preventative to effective construction and operation of the solar farm and will not be
altered.
Please see Appendix C2 - Biological Resources report and C11- Geotech Engineering report for further
detail on soils and geology at the site.
NARRATIVE RESPONSE TO IMPACT ANALYSIS (SECTION 4-203G)
Section B12
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AES High Mesa Solar – Garfield County 43
Geology and Hazards
In relation to Section 7-207, page C01-04 of the Site Plan illustrating Pre-existing Conditions in Section
B2 shows the various categories of slopes in the project area, denoting them as less than 20%, 20% - 30%,
and greater than 30%. As can be seen in the site plan, no portion of the solar array or access infrastructure
will be placed in the areas greater than 20%, and therefore does not prompt applicable Slope Development
minimum requirements and standards for steeper slopes.
Furthermore, there are no significant geological features or constraints that the Project would encounter
that would prove insurmountable to appropriate engineering design and professional recommendations.
The following excerpt from the Geotech Report summarizes model layers of subsurface formations:
Please see Appendix C11 for the Geotech report for further detail on soils and geology at the site.
Groundwater and Aquifer Recharge Areas
As drainage patterns will not be altered and there is a limited change of impervious surface area to 0.93-
acre total, or 1.23% of the property, the Project is not expected to have any impacts to groundwater
resources. There will be no on-site waste or sewage disposal to affect such resources, and there will be
no generation of other wastes or effluents to affect surface runoff from natural conditions.
Environmental Impacts
Flora and Fauna
As detailed in the Biological Resources report, the Project has adhered to CPUC Rule 3668 and
conducted pre-development wildlife surveys to identify, avoid, and minimize potential impacts to
wildlife and their habitats. HDR on behalf of AES has coordinated extensively with Colorado Parks and
Wildlife (CPW) to verify conclusions on limited wildlife impact and appropriate construction practices
and mitigation approaches.
Suitable habitat occurs in the project area for the Colorado Hookless Cactus - CHC (Sclerocactus
glaucus), two state species, and migratory birds. An in-season survey was conducted within the
proposed site on May 25, 2021 but did not detect the CHC. Suitable habitat occurs in the project area for
two state listed species of special concern (not a statutory category), the midget faded rattlesnake
(Crotalus concolor) and northern leopard frog (Lithobates pipiens). However, the project will not impact
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
AES High Mesa Solar – Garfield County 44
key components of suitable habitat (aquatic features and rocky outcroppings), thereby avoiding adverse
effects on the two state listed species. No other federal or state protected species have the potential to
occur in the proposed site or be impacted by project activities.
Furthermore, per CPW’s Recommendations to Avoid and Minimize Impacts to Wildlife from Land Use
Development in Colorado, and the presence within the Project area of severe winter range and winter
concentration area for elk and mule deer, AES will not conduct construction activities between
December 1 to April 30 in those areas identified in the maps in the Biological Resources report. The
Project will also employ wildlife-friendly fencing and ongoing consultation will be maintained with
CPW on their recommendation of 1:1 habitat improvement elsewhere for lost grazing habitat.
No nesting sites for eagles or other raptors were detected during the site survey or otherwise occur
within the project area or within a 0.5 mile radius of the project boundary. Therefore, no impacts on
nesting raptors would occur as a result of the project. However, as construction is scheduled to occur
within of the general nesting season (May 1 – July 31) for most migratory birds, then clearance surveys
for nesting activity would be performed no more than one week prior to the start of project activities.
With the implementation of pre-construction clearance surveys for nesting birds and a strategic
construction approach and design, no adverse effects would occur on state or federal protected species
and migratory birds.
Lastly, use of native and drought tolerant seed mixes detailed in the Vegetation Management plan
should result in improved quality of grass and plant populations at the site and a decline in invasive
weed species. The current site plan does anticipate some clearing of juniper trees in the southern section
of the project area due to impacts of the 100 ft setback requirement for industrial uses in Rural zoned
areas; however, to the extent it can be avoided, AES will seek to do so.
Please see Appendix C2 for the Biological Resources report prepared by HDR on behalf of AES and our
response to 7-202 Wildlife Habit for further analysis and conclusions on impact assessment and
avoidance.
Wetlands
The delineation of waters of the US within the project area is based on the best professional judgement
of HDR’s team of wetland delineators. The wetland delineation identified three unconsolidated bottom,
emergent wetlands totaling 0.499 acre, and two irrigation ditches with ephemeral flow, one ephemeral
stream, one irrigation ditch with intermittent flow, and one intermittent stream totaling 1.389 acres. The
survey and analysis do not constitute an Approved Jurisdictional Determination, which can only be
officially rendered by the USACE Regulatory Branch through the formal review process. However,
none of the aquatic features identified in the project area are believed to be a water of the US. Please
refer Section 6.0 Discussion to the formal project delineation report for specifics pertaining to why the
aquatic features are believed to be non-jurisdictional. Still, effects on aquatic features in the project area
would be avoided during construction by use of 35-foot setbacks to wetlands and 20-foot setbacks to
ditches.
AES High Mesa Solar – Land Use Change – Major Impact permit application (10/22/2021)
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See Appendix C1 for the Delineation and Proposed Jurisdictional Determination of the US – AES High
Mesa Solar, LLC wetland report conducted in November 2020 and published in February 2021.
Nuisance
Solar energy projects operate quietly, unmanned without daily traffic, and without emissions, water
usage, or input fuels outside of natural sunshine. As a clean, renewable energy system, there are no
emissions produced from the Project itself.
Air Quality
AES will use best practices to manage dust during construction. The emissions from construction are
anticipated to be below thresholds set by the Colorado Department of Public Health and Environment
(CDPHE) for Colorado’s Air Pollutant Emission Notice (APEN) system. The site access roads will be
graveled for long-term use, and during the six-to-eight-month construction period appropriate measures
will be taking to minimize dust from the delivery trucks and tracking of mud, when traffic will be at its
peak of the Project’s lifetime.
Glare
With regards to concerns over glare from the solar farm, the solar panels are tracking in nature, which
means that they will rotate to face the sun as it passes overhead. This factor, combined with the solar
panel’s anti-reflective coating, will minimize any reflected light (glare). Modern PV modules use a
sophisticated anti-reflective (AR) coating to nearly eliminate the reflection of sunlight off the module
face. A typical human eye reacts to light wavelengths from 390 to 700 nanometers and in that spectrum,
the AR-coated glass on a module will have a transmittance of at least 93%. Transmittance is the percent
of radiation (light) that travels through a surface. Having such a high level of transmittance is valuable
because it means that more light is traveling through the glass and onto the solar PV cells rather than
reflecting off the surface. With transmittance values higher than a body of water or a glass window
without an AR coating, the potential for glare is lower for a solar farm compared to these other surfaces.
Please see Appendix C7 for the SolarForge Glare Analysis performed specifically for the High Mesa
project’s location, taking in several observational points adjacent to the project including homes and
roadways. ForgeSolar tools are used throughout the world by industry, academia, and military to
evaluate PV glare. Based on the R&D 100 Award-winning SGHAT technology, ForgeSolar
accommodates FAA, zoning, and other regulatory requirements.
No green or yellow category glare was detected in the analysis from any point. This is in large part due
to the east-west tracking nature of the facility and fluctuating tilt of the panels so that in no instance are
they ever oriented directly at any homes or road ways at discernible heights. The location of the Project
is far from Rifle airport and outside of the 2-mile flight path.
Noise
No action necessary. Installation of solar arrays create minimal amount of noise and vibrations.
Typically, the PV inverters and transformers will emit minimal noise at ~50 decibels when standing
within 10 feet, which is equivalent to a conversation level within that range. During operations the
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facilities will be unmanned and will operate quietly and automatically with only infrequent maintenance
visits.
Hours of Operation
The Project once in operation, will operate 24/7 but will be unmanned and remotely monitored for
performance and alerted for necessary maintenance. Maintenance trips to the site will be no more than
once per month by a small crew of technicians, and likely even less than that frequency. During
construction, work hours will be limited to daytime hours and within 7am-7pm time frame, and
primarily on weekdays unless circumstances require weekend work. AES will comply with any working
hour restrictions that the county indicates outside of these standards conditions.
Lot Coverage
While the Project will conform to the listed setback requirements for an Industrial Use in the the Rural
Zone District, AES notes that Zone District Dimensions per Table 3-201 include a 15% Maximum Lot
Coverage in such districts. The Pre-Application Summary mentions that the Land Use Development
Code (LUDC) does not specify requirements on lot coverage specific to solar facilities and will be
decided appropriately by the Board of County Commissioners (BOCC).
In any case, the following calculations exerpted from Appendix C6 – Stormwater Memo demonstrate
that the total coverage ratio of the Project to that of the property to be far short of the maximum lot
coverage requirement.
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Please see the following pages for the Delineation and Proposed Jurisdictional Determination of Waters
of the US – AES High Mesa Solar, LLC wetland report conducted in November 2020 and published in
February 2021.
DELINEATION & PROPOSED JURISDICTIONAL DETERMINATION
OF WATERS OF THE US
Appendix C1
Delineation and Proposed
Jurisdictional Determination
of Waters of the US
AES High Mesa Solar, LLC
Klebold Parcel
Garfield County, Colorado
February 2021
AES High Mesa Solar, LLC | Klebold Parcel
Delineation and Proposed Jurisdictional Determination of Waters of the US
TOC-i
CONTENTS
1.0 BACKGROUND AND INTRODUCTION.............................................................................. 1
2.0 REGULATORY FRAMEWORK ........................................................................................... 1
3.0 ENVIRONMENTTAL SETTING .......................................................................................... 1
3.1 Location .......................................................................................................................... 1
3.2 Climate ........................................................................................................................... 1
3.3 Vegetation ...................................................................................................................... 1
3.4 Soils ............................................................................................................................... 2
3.5 Hydrology ....................................................................................................................... 2
4.0 DELINEATION METHODOLOGY ....................................................................................... 2
4.1 Wetlands and Streams ................................................................................................... 2
5.0 RESULTS ........................................................................................................................... 3
5.1 Wetlands ........................................................................................................................ 3
5.2 Streams .......................................................................................................................... 4
6.0 DISCUSSION ..................................................................................................................... 5
7.0 REFERENCES ................................................................................................................... 7
Appendices
Appendix A. Figures
Appendix B. Antecedent Precipitation Tool
Appendix C. Ordinary High Water Mark Datasheet
Appendix D. Site Photographs
Tables
Table 1. Wetlands Within the Study Area .................................................................................. 3
Table 2. Streams Within the Study Area .................................................................................... 4
Table 3. Proposed Jurisdictional Determination ......................................................................... 4
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1.0 BACKGROUND AND INTRODUCTION
AES High Mesa Solar, LLC is in the preliminary stages of land acquisition in Garfield County,
Colorado for future photovoltaic array facilities construction, hereafter referred to as the project.
The proposed lands are situated in a rural, agricultural area in the western slope of Colorado,
approximately 3.5 miles southwest of Parachute, Colorado (see Appendix A, Figure 1). The
approximately 257-acre Klebold Parcel (Study Area) is located on the southeast side of County
Road (CR) 300 (also known as Stone Quarry Road), just northeast of CR 306 (also known as
Wallace Creek Road) in Sections 35 and 36 of Township 7 South, Range 96 West. The Study
Area consists primarily of agricultural land with irrigation ditches and impoundments throughout.
The purpose of this report is to document the type, size, and location of aquatic resources in the
Study Area, including wetlands and waters of the US. Based on a desktop analysis and site
survey conducted in November 2020, there are three wetland features totaling 0.499 acre. In
addition to the wetlands, there are two ephemeral irrigation ditches, one ephemeral stream, and
two intermittent streams totaling 1.392 acres (7,326 linear feet).
2.0 REGULATORY FRAMEWORK
The Navigable Waters Protection Rule: Definition of “Waters of the United States” (NWPR)
became effective on June 22, 2020. However, at the time of the delineation, a court-issued stay
is in place for NWPR in the State of Colorado. As a result, waters of the US in Colorado are
defined according to 33 CFR Part 328.3 prior to NWPR and the most recently approved
guidance from the US Army Corps of Engineers (USACE) and US Environmental Protection
Agency (EPA), which was published December 2, 2008 (USACE and EPA 2008). The guidance
was issued pursuant to the US Supreme Court findings in the Rapanos and Carabell cases and
is herein referred to as the Rapanos Guidance.
3.0 ENVIRONMENTTAL SETTING
3.1 Location
The project is located within the Parachute, CO United States (2019) Geological Survey
quadrangle unit. The center coordinates are 39.39585, -108.07320 (World Geodetic System
[WGS] 84).
3.2 Climate
The Study Area is also within the Warm Central Desertic Basins and Plateaus Major Land
Resource Area (MLRA). This MLRA receives most of its annual precipitation (6 to 10 inches)
from snowfall in higher elevations and convective storms in late summer. The average annual
temperature ranges from 41 to 54 degrees Fahrenheit. The freeze-free period averages 160
days and ranges from 110 to 235 days (Natural Resources Conservation Service [NRCS],
2006).
3.3 Vegetation
Vegetation observed within the Study Area is consistent to that of disturbed agricultural
landscapes in Colorado and includes: Utah juniper (Juniperus osteosperma), crested
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Delineation and Proposed Jurisdictional Determination of Waters of the US
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wheatgrass (Agropyron cristatum), big sagebrush (Artemesia tridentata), rubber rabbitbrush
(Ericameria nauseosa), kochia (Bassia scoparia), cocklebur (Xanthium strumarium), squirreltail
(Elymus elymoides), Russian thistle (Kali tragus), curlycup gumweed (Grindelia squarrosa), and
fourwing saltbush (Atriplex canescens).
Wetland and riparian vegetation includes plains cottonwood (Populus deltoides), sandbar willow
(Salix exigua), spikerush (Eleocharis sp), and smartweed (Persicaria sp.).
3.4 Soils
The Web Soil Survey maps seven soil map units within the Study Area (see Appendix A, Figure
4):
• Ildefonso stony loam, 25 to 45 percent slopes;
• Niill channery loam, 25 to 45 percent slopes;
• Potts loam, 3 to 6 percent slopes;
• Potts loam, 6 to 12 percent slopes;
• Potts-Ildefonso complex, 12 to 25 percent slopes;
• Potts-Ildefonso complex, 25 to 45 percent slopes; and
• Torriorthents-Camborthids-Rocky outcrop complex, steep.
According to NRCS, none of the seven soils are considered hydric based on the field indicators
known to be associated with soils that meet the definition of a hydric soil (NRCS 2020a, NRCS
2020b).
3.5 Hydrology
The majority of the Study Area drains east to Pete and Bill Creek and north to the Colorado
River, approximately 2 miles north of the Study Area. The Colorado River flows west and
empties into the Gulf of California approximately 665 miles southwest of the Study Area.
4.0 DELINEATION METHODOLOGY
4.1 Wetlands and Streams
HDR, Inc. (HDR) conducted an on-site routine delineation for wetlands and other waters of the
US in the Study Area on November 4, 2020 in accordance with the 1987 Corps of Engineers
Wetlands Delineation Manual (Environmental Laboratory, 1987), A Field Guide to the
Identification of the Ordinary High Water Mark (OHWM) in the Arid West Region of the Western
United States (USACE 2008a), the Regional Supplement for the Arid West (USACE 2008b),
and the Updated Datasheet for the Identification of the Ordinary High Water Mark (OHWM) in
the Arid West Region of the Western United States (USACE 2010).
According to the USACE Antecedent Precipitation Tool (APT), the Palmer Drought Severity
Index indicated Severe Drought conditions at the time of the delineation (see Appendix B).
Additionally, the APT indicated drier than normal conditions were present at the time of the
delineation in November. Drier than normal conditions were also present during the months of
August, September, and October (USACE 2020). According to the NRCS Agricultural Applied
Climate Information System (AgACIS) Altenbern, CO recorded less than average precipitation
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for the month of October. The 20-year average is 1.99 inches of precipitation. In November
2020 the station recorded 1.05 inches (AACIS 2020). As a result, observed areas may have
been drier than average and flow rates within the identified waterways may have been less than
normal.
Prior to field delineations, a desktop analysis was conducted using National Wetlands Inventory
(NWI) maps (USFWS 2020), the National Hydrography Dataset (NHD) (USGS 2014), NRCS
Soil Survey (NRCS 2020), and USDA NRCS color aerial photographs (USDA 2020) to identify
aquatic resources (see Appendix A, Figure 4).
Wetland boundaries were mapped in the field using sub-meter GPS technology and were
classified according to Classification of Wetlands and Deepwater Habitats of the United States
(Cowardin et al., 1979). The average Ordinary High Water Mark was delineated (USACE 2007)
and recorded on a form provided in Appendix C. Representative photos of the Study Area,
including aquatic resources, are provided in Appendix D.
5.0 RESULTS
The results are presented in two sub-sections: wetlands and streams. The results are also
provided in Appendix A, Figure 3. The Ordinary High Water Mark datasheet is provided in
Appendix C and Site Photographs are available in Appendix D.
5.1 Wetlands
The delineation resulted in the identification of three emergent wetlands, totaling 0.499 acre
within the Study Area (see Table 1).
Table 1. Wetlands Within the Study Area
Wetland
ID
Wetland Classification
(Cowardin)*
Area
(acres)
W-1 PEM 0.27
W-2 PEM 0.04
W-3 PEM 0.19
TOTAL 0.5
Notes:
*Cowardin et al., 1979 Classification: PUB = Unconsolidated Bottom, non-tidal
wetland dominated by persistent emergent vegetation
Emergent wetlands W-1, W-2, and W-3 are located in the western portion of the Study Area.
These wetlands are classified as unconsolidated bottom wetlands with a subclassification of
mud and organic matter and are seasonally flooded (Cowardin et al, 1979). These wetlands are
the result of creating impoundments on contour for agricultural purposes. The wetlands receive
hydrology from overland flow after precipitation events, possibly from groundwater pumping,
and were dry at the time of the delineation. The wetlands are dominated by a combination of
upland plants including squirreltail (Elymus elymoides), curlycup gumweed (Grindelia
squarrosa), cocklebur (Xanthium strumarium), plains cottonwoods (Populus deltoides), and also
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wetland plants such as sandbar willow (Salix exigua) and smartweed (Persicaria sp.). Within the
Study Area, wetlands W-1, W-2, and W-3 are 0.27, 0.04, and 0.19 acre in size, respectively.
These wetlands were delineated by OHWM and the hydrophytic versus upland vegetation
cover.
5.2 Streams
The November 2020 survey identified two ephemeral irrigation ditches, one ephemeral stream,
one intermittent irrigation ditch, and one intermittent stream within the Study Area (see Table 2).
Table 2. Streams Within the Study Area
Channel
ID
OHWM
Width
(Feet)
Type
Channel
Length (LF)
Channel
Area (acre)
S-1 2 Irrigation Ditch (Ephemeral Flow) 2,358 0.108
S-2 1 Irrigation Ditch (Ephemeral Flow) 42 0.001
S-3 6 Irrigation Ditch (Intermittent Flow) 1,022 0.136
S-4 13 Intermittent Stream 3,737 1.13
S-5 4 Ephemeral Stream 167 0.014
TOTAL 7,326
1.389
Ephemeral streams S-1 and S-2 are unnamed irrigation ditches that distribute water to
agricultural fields in the center of the Study Area. At the time of the survey there was no water in
the channels. Within the Study Area, streams S-1 and S-2 have an average OHWM of 2 feet
and 1 foot, respectively, and are 0.108 acre (2,358 LF) and 0.001 acre (42 LF) in size,
respectively.
Streams S-3 and S-4 are intermittent stream features in the southeastern portion of the Study
Area. Stream S-3 is a constructed irrigation ditch that flows from, alongside, and back into
intermittent stream S-4. Stream S-4 is a naturally occurring intermittent stream and tributary of
the Colorado River named Pete and Bill Creek. Riparian vegetation included western
wheatgrass, squirreltail, curly cup gumweed, cocklebur, rubber rabbitbrush, fourwing saltbush,
and plains cottonwood. Stream S-4 contains a hillside seep that contributes to the stream’s
hydrology. At the time of survey, a small, 1-foot channel of water was flowing in the wider
6-foot-wide average OHWM. Within the Study Area, streams S-3 and S-4 have an average
OHWM of 6 and 13 feet, respectively, and are 0.136 acre (1,022 LF) and 1.13 acres (3,737 LF)
in size, respectively.
Stream S-5 is an ephemeral stream feature in the southeastern portion of the Study Area.
Stream S-5 converges with intermittent stream S-4 and flows north. At the time of the survey
there was no water in the channel. Within the Study Area, stream S-5 has an average OHWM
width of 4 feet and is 0.014 acre (167 LF) in size.
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6.0 DISCUSSION
The delineation identified three unconsolidated bottom wetlands, two irrigation ditches with
ephemeral flow, one ephemeral stream, one irrigation ditch with intermittent flow, and one
intermittent stream.
According to the 1986/1987 definition of waters of the US and post-Rapanos regulatory
guidance, none of the aquatic resources except streams S-3, S-4, and S-5 would be considered
waters of the US (see Table 3). The three unconsolidated bottom wetlands and two ephemeral
irrigation ditches are considered non-jurisdictional features because they were
excavated/created in uplands, do not replace or impound a tributary of a traditional navigable
water, and do not have a significant nexus to a traditional navigable water (51 Fed. Reg. 41,217
[November 13, 1986]; USACE and EPA 2008). Intermittent stream S-4 and ephemeral stream
S-5 would be considered jurisdictional since they are considered tributaries of the Colorado
River. Additionally, intermittent irrigation ditch S-3 would be considered jurisdictional since it has
a significant nexus, in that it contributes flow to significantly affect the chemical, physical, and
biological integrity of a traditional navigable water (i.e., the Colorado River).
If NWPR goes into effect in the state of Colorado, wetlands W-1, W-2, and W-3 would not be
considered waters of the US since they are artificial lakes and ponds used for irrigation and/or
stock watering, were constructed in uplands, and are not an impoundment of a jurisdictional
water. Ephemeral irrigation ditches S-1 and S-2 would not be waters of the US since they were
constructed in uplands and do not replace a tributary or adjacent wetland considered to be a
water of the US. Ephemeral stream S-5 is not considered a water of the US since it is an
ephemeral feature, which includes ephemeral streams, swales, gullies, rills, and pools (85 Fed.
Reg. 22340 [April 21, 2020]). Intermittent stream S-4 would be considered a water of the US
since it is considered a tributary according to NWPR. Intermittent irrigation ditch S-3 would also
be considered jurisdictional since it is considered a relocated tributary by flowing from
intermittent stream S-4 and back into intermittent stream S-4.
Table 3. Proposed Jurisdictional Determination
Aquatic
Resource ID Post-Rapanos1 NWPR2
W-1 NJD NJD
W-2 NJD NJD
W-3 NJD NJD
S-1 NJD NJD
S-2 NJD NJD
S-3 JD JD
S-4 JD JD
S-5 JD NJD
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Aquatic
Resource ID Post-Rapanos1 NWPR2
1 Based on the 1986 definition of waters of the US and associated
regulatory guidance, including the Rapanos Guidance (USACE and
EPA 2008)
2 Based on the Navigable Waters Protection Rule at 85 Fed. Reg.
22,250 (April 21, 2020)
Notes:
JD: Jurisdictional (i.e., water of the US)
NJD: Non-Jurisdictional (i.e., not a water of the US)
See paragraphs above for explanation of the jurisdictional
determination
This delineation and proposed jurisdictional determination of waters of the US within the Study
Area is based on the best professional judgement of HDR’s team of wetland delineators, who
have extensive experience with delineation and permitting of wetlands and other aquatic
resources in the southwest region of the US. However, it does not constitute an Approved
Jurisdictional Determination, which can only be officially rendered by the USACE Regulatory
Branch through the formal review process.
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7.0 REFERENCES
Agricultural Applied Climate Information System (AACIS). 2020. Shoshone, CO WETS Station.
Accessed November 2020. http://agacis.rcc-acis.org/?fips=31153.
Cowardin, et al. 1979. Classification of Wetlands and Deepwater Habitats of the United States.
FWS/OBS-79/31. US Department of the Interior, Washington D.C.
Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual. Technical
Report Y-87-1. US Army Engineer Waterways Experiment Station. Vicksburg,
Mississippi.
Natural Resources Conservation Service (NRCS). 2020a. Web Soil Survey. United States
Department of Agriculture. Accessed November 2020.
https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm.
. 2020b. National Hydric Soils Listed by State: New Mexico. Accessed November 2020
online at http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/use/hydric/.
United States Army Corps of Engineers (USACE) and United States Environmental Protection
Agency (EPA). 2008. Clean Water Act Jurisdiction Following the US Supreme Court's
Decision in Rapanos v. United States & Carabell v. United States. December 2008.
Accessed November 2020. https://www.epa.gov/sites/production/files/2016-
02/documents/cwa_jurisdiction_following_rapanos120208.pdf.
USACE. 2007. US Army Corps of Engineers Jurisdictional Determination Form Instructional
Guidebook. Appendix H RGL 05-05 Ordinary High Water Mark (OHWM) Identification,
May 30, 2007.
. 2008a. Regional Supplement to the Corps of Engineers Wetland Delineation Manual:
Arid West Region (Version 2.0), ed. J. S. Wakeley, R. W. Lichvar, and C. V. Noble.
ERDC/EL TR-08-28. Vicksburg, MS: US Army Engineer Research and Development
Center.
. 2008b. A Field Guide to the Identification of the Ordinary High Water Mark (OHWM) in
the Arid West Region of the Western United States – A Delineation Manual, Robert W.
Lichvar and Shawn M. McColley. ERDC/CRREL TR-08-12. Hanover, NH.
. 2010. Updated Datasheet for the Identification of the Ordinary High Water Mark
(OHWM) in the Arid West Region of the Western United States, ed. K.E. Curtis and R.W.
Lichvar. ERDC/CRREL TN-10-1. Vicksburg, MS: US Army Engineer Research and
Development Center.
. 2020. Antecedent Precipitation Tool, version 1.0. Accessed November 2020.
https://github.com/jDeters-USACE/Antecedent-Precipitation-Tool/releases/tag/v1.0.3.
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USFWS. 2020. “Overview.” National Wetlands Inventory Mapper. US Department of the Interior,
Fish and Wildlife Service, Washington, D.C. April. Accessed November 2020.
http://www.fws.gov/wetlands/.
US Geological Survey (USGS). 2014. National Hydrography Dataset. Accessed November
2020. https://viewer.nationalmap.gov/advanced-viewer/index.html?p=nhd.
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Delineation and Proposed Jurisdictional Determination of Waters of the US
Appendix A.
FIGURES
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Delineation and Proposed Jurisdictional Determination of Waters of the US
Appendix B.
ANTECEDENT
PRECIPITATION TOOL
Apr
2020
May
2020
Jun
2020
Jul
2020
Aug
2020
Sep
2020
Oct
2020
Nov
2020
Dec
2020
Jan
2021
Feb
2021
Mar
2021
0.0
0.5
1.0
1.5
2.0
2.5
Rainfall (Inches)2020-11-04
2020-10-05
2020-09-05
Antecedent Precipitation vs Normal Range based on NOAA's Daily Global Historical Climatology Network
Daily Total
30-Day Rolling Total
30-Year Normal Range
30 Days Ending 30th %ile (in)70th %ile (in)Observed (in)Wetness Condition Condition Value Month Weight Product
2020-11-04 0.902362 2.058661 0.283465 Dry 1 3 3
2020-10-05 1.235433 2.625197 1.169291 Dry 1 2 2
2020-09-05 0.985827 1.609449 0.799213 Dry 1 1 1
Result Drier than Normal - 6
Coordinates 39.395703, -108.073058
Observation Date 2020-11-04
Elevation (ft)5502.11
Drought Index (PDSI)Extreme drought
WebWIMP H2O Balance Wet Season
Weather Station Name Coordinates Elevation (ft)Distance (mi)Elevation Weighted Days (Normal)Days (Antecedent)
ALTENBERN 39.4992, -108.3808 5637.139 17.909 135.029 10.477 11253 90
BATTLEMENT MESA 0.8 WSW 39.4368, -108.0383 5363.845 3.392 138.265 1.995 2 0
PARACHUTE 3.5 E 39.4537, -107.9869 6040.026 6.099 537.916 6.026 4 0
DE BEQUE 7.1 SSE 39.2408, -108.1538 5605.971 11.54 103.861 6.392 1 0
RIFLE .96 NNW 39.5483, -107.7873 5425.853 18.533 76.257 9.753 61 0
RIFLE GARFIELD CO AP 39.5264, -107.7264 5529.856 20.579 27.746 9.832 32 0
AES High Mesa Solar, LLC | Klebold Parcel
Delineation and Proposed Jurisdictional Determination of Waters of the US
Appendix C.
ORDINARY HIGH
WATER MARK
DATASHEET
Arid West Ephemeral and Intermittent Streams OHWM Datasheet
Project: Date: Time:
Project Number: Town: State:
Stream: Photo begin file#: Photo end file#:
Investigator(s):
Y / N Do normal circumstances exist on the site?
Y / N Is the site significantly disturbed?
Location Details:
Projection: Datum:
Coordinates:
Potential anthropogenic influences on the channel system:
Brief site description:
Checklist of resources (if available):
Aerial photography
Dates:
Topographic maps
Geologic maps
Vegetation maps
Soils maps
Rainfall/precipitation maps
Existing delineation(s) for site
Global positioning system (GPS)
Other studies
Stream gage data
Gage number:
Period of record:
History of recent effective discharges
Results of flood frequency analysis
Most recent shift-adjusted rating
Gage heights for 2 -, 5 -, 10 -, and 25-year events and the
most recent event exceeding a 5 -year event
Procedure for identifying and characterizing the floodplain units to assist in identifying the OHWM:
1. Walk the channel and floodplain within the study area to get an impression of the geomorphology and
vegetation present at the site.
2.Select a representative cross section across the channel. Draw the cross section and label the floodplain units.
3. Determine a point on the cross section that is characteristic of one of the hydrogeomorphic floodplain units.
a) Record the floodplain unit and GPS position.
b) Describe the sediment texture (using the Wentworth class size) and the vegetation characteristics of the
floodplain unit.
c) Identify any indicators present at the location.
4. Repeat for other points in different hydrogeomorphic floodplain units across the cross section.
5. Identify the OHWM and record the indicators. Record the OHWM position via:
Mapping on aerial photograph GPS
Digitized on computer Other: