HomeMy WebLinkAbout1.18 Land Suitability Analysis
LAND SUITABILITY
ANALYSIS
RIVER EDGE COLORADO
GARFIELD COUNTY, COL ORADO
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Land Suitability Analysis
River Edge Colorado, Garfield County, Colorado
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LAND SUITABILITY ANALYSIS
RIVER EDGE COLORADO
GARFIELD COUNTY, COL ORADO
TABLE OF CONTENTS
I. INTRODUCTION ........................................................................... 4
A. BASIS .................................................................................................... 4
B. PURPOSE AND SCOPE OF ANALYSIS ........................................................ 4
C. REFERENCES .......................................................................................... 4
D. SUMMARY OF ANALYSIS ........................................................................ 4
II. PROJECT LOCATION AND DESCR IPTION .......................................... 5
A. PROJECT LOCATION ........................... ERROR! BOOKMARK NOT DEFINED.
B. PROJECT DESCRIPTION ...................... ERROR! BOOKMARK NOT DEFINED.
III. LAN D SUITABILITY ANALYS IS ......................................................... 5
A. PUBLIC ACCESS TO SIT E ......................................................................... 5
B. ACCESS TO ADJOINING ROADWAYS ........................................................ 6
C. EASEMENTS .......................................................................................... 7
D. TOPOGRAPHY AND SLOPE ...................................................................... 8
E. NATURAL FEATURES ............................................................................... 8
F. DRAINAGE FEATURES ............................................................................. 9
G. WATER .................................................................................................. 9
1. POTABLE WATER SUPPLY AND SOURCE ..................................................... 9
2. IRRIGATION WATER ................................................................................. 10
3. IRRIGATION WATER RETURN FLOWS ....................................................... 10
H. FLOODPLAINS ...................................................................................... 11
I. SOILS .................................................................................................. 11
J. HAZARDS ............................................................................................ 12
1. EVAPORITE SINK HOLES ........................................................................... 12
2. STEEP TERRACE ESCARPMENTS ............................................................... 13
3. ACTIVE STREAM BANK EROSION ............................................................. 13
4. DEBRIS FLOW AND FLOODS ..................................................................... 13
5. EARTHQUAKES ......................................................................................... 14
6. RADIATION ............................................................................................... 14
K. NATURAL HABITAT ............................................................................... 15
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1. VEGETATIVE COVER ................................................................................. 15
2. HABITAT AREAS AND GENERAL WILDLIFE USE ........................................ 16
3. SPECIFIC SPECIES OF SPECIAL IMPORTANCE ........................................... 18
L. RESOURCE AREAS ................................................................................ 20
APPENDICES
APPENDIX A: VICINITY MAP AND PROJECT SITE LOCATION
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I. INTRODUCTION
A. BASIS
This Land Suitability Analysis ("Analysis") has been prepared in support of an application
for PUD Plan Review ("Rezoning") and Subdivision Review ("Preliminary Plan") for the
proposed River Edge Colorado ("Project", "REC", "REC PUD", or "development") in
accordance with the requirements of the Garfield County Unified Land Use Resolution of
2008 ("ULUR"), as amended. This Analysis specifically addresses the standards of Section
4-502.D as required by Section 5-501.G.8 and 6-301.B.5.c of the ULUR. The Analysis is
supported by other referenced documents submitted as part of the REC rezoning and
preliminary plan applications including the River Edge Colorado PUD (Rezoning) and
Subdivision (Preliminary Plan) Drawing Package ("Drawing Package"). For a complete
understanding of this Analysis and its findings, this Analysis should be reviewed in
conjunction with the other materials submitted as part of the REC rezoning and
preliminary plan applications.
B. PURPOSE AND SCOPE OF ANALYSIS
This Analysis supports the review of the Project. The intent of this Analysis is to provide
Garfield County with an understanding of the existing land and development conditions
and constraints associated with the Project Site (as herein after defined) that should be
considered in the design of the Project. The scope of this Analysis is limited to the land
suitability analysis components outlined in Section 4-502.D of the ULUR.
C. REFERENCES
As stated in Section I.A of this Analysis, this Analysis relies upon several documents that
were submitted concurrently with this Analysis as part of the REC rezoning and
preliminary plan applications. The associated documents include the following:
Existing Conditions and Land Suitability Plan, Series EC01 of the Drawing
Package (See also Data Sources)
Water Supply Report, 8140 Partners, LLC, January 14, 2011
Impact Analysis, 8140 Partners, LLC, January 14, 2011
D. SUMMARY OF A NALYSIS
The information presented in Section III of this Analysis identifies the access to the site,
access to adjoining roadways, easements, topography and slope, natural features,
drainage features, water, floodplain, soils, hazards, natural habitat and resource areas.
These features and conditions were used as a basis for planning and laying out the
Project. The Impact Analysis assess the relationship of the Project to these features and
conditions, while a variety of design reports address the specific issues resulting or
influencing the preliminary design of the Project and associated facilities and
infrastructure.
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II. PROJECT LOCATION
The Project is located along State Highway 82 ("SH 82") between the City of Glenwood
Springs and Town of Carbondale near the junction of County Road 110/113 ("CR 113")
and SH 82. The property is located almost entirely west of the Roaring Fork Transit
Authority ("RFTA") right-of-way and east of the Roaring Fork River and the Roaring Fork
Conservancy ("RFC") Conservation Easement (i.e., Grant of Conservation Easement
dated February 3, 2000, recorded at Reception Number 559036 and survey map,
recorded December 24th, 2008, recorded at Reception Number 760571 in the real
property records of Garfield County, Colorado). The Project straddles Cattle Creek which
is also located within the RFC Conservation Easement. A vicinity map is provided as
Exhibit 1 in Appendix A1. The Project covers approximately 160 acres ("Project Site") as
shown and described on the Project Site drawing [Exhibit 2(a-d), Appendix A1]. The
Project is proposed by Carbondale Investments, LLC ("CI").
III. LAND SUITABILITY ANALYSIS
This section of the Analysis details the existing conditions as identified in Section 4-
502.D of the ULUR. The Analysis is ordered in accordance with Section 4-502.D of the
ULUR. The land suitability information referenced by the following sections is, where
appropriate, depicted on Existing Conditions and Land Suitability Plan, Series EC01 of
the Drawing Package.
A. PUBLIC ACCESS TO SIT E
The Project Site takes access from SH 82, but does not directly adjoin the highway
except for Tract AY which is within a RFTA open space easement. Access is provided
across the RFTA right-of-way which abuts the Colorado Department of Transportation
("CDOT") right-of-way directly.
A State Highway Access Permit will be required to take access to SH 82 at CR 113. The
access will also require a crossing of the RFTA right-of-way immediately west of SH 82.
All permitting will be done via the State and RFTA process at time of final plat. The Level
III Traffic Study will be prepared prior to final plat and needs to include the standard
Level 3 Traffic Study documentation and recommendations for the entire intersection,
including the east half of the intersection. The intersection design may include short
term recommendations if the final intersection layout is not appropriate to construct at
until sometime after the Project begins or if some improvements are not the
responsibility of CI. Addressing CR 113 will require additional coordination between CI,
the County, and CDOT as the design progresses.
The RFTA right-of-way crossing required by the entry road at CR 113 and SH 82 is
covered by an Easement Grant providing at-grade access to the Project Site. The
easement for access to the Project Site at this location was granted by RFRHA (now
RFTA) in Book 1142 at Page 963 (amended Book 1217 at Page 588) in the records of the
Garfield County Clerk and Recorder (See Appendix H of the Impact Report). Several
other access and utility agreements and licenses are also noted on the ALTA (Series V01)
and Existing Conditions and Land Suitability Plan (Series EC01) of the Drawing Package.
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These licenses are not proposed for use at this time, but are also granted to adjacent
properties and may support future development adjacent to the Project Site.
The access is proposed as a private access. No through traffic is currently provided for
by the REC PUD and no public uses are proposed within the REC PUD. As such, no public
need exists for access to or through the development and public ownership and
maintenance of the roads with in the development are not warranted. In the event, the
private roads are converted to public access, a public entity meeting the requirements
of Part 7 Rules Regulating Railroads, Rail Fixed Guideways, Transportation by Rail, and
Rail Crossings of 4 Code of Colorado Regulations ("CCR") 723-7 ("PUC Rules")
administered by the PUC would be required to take over control of the crossing and
comply with any other applicable laws. The private access will be required to be
designed and constructed to RFTA standards as a future at-grade rail crossing.
Emergency Vehicle Access ("EVA") agreements are in place provides for construction of
a 20 foot EVA across the property to a point along SH 82 as is convenient for the
development of the adjacent property.
Access to the site is generally limited to the locations specified unless new provisions
are made for access. Project analysis must consider the design of these locations.
Development may be limited by the ability of these access locations to meet Project
demands.
B. ACCE SS TO ADJOINING ROAD WAYS
Exhibit 1 in Appendix B shows the existing road network in the vicinity of the Project and
proposed access point.
The Project will likely take access from SH 82, a State Highway, at CR 113. The current
access to the site exists at this point. SH 82 is a median divided rural highway with two
lanes in each direction. Auxiliary turn lanes exist at full movement intersections as well
as acceleration and deceleration lanes. The speed limit along SH 82 in the vicinity of the
Project varies from 55 to 65 miles per hour. SH 82 is classified as an Expressway,
Category E‐X by CDOT. According to the State of Colorado Access Code, direct access
service to abutting land is subordinate to providing service to through traffic
movements. CR 113 intersects CR 110 and Frontage Road prior to intersecting SH 82 on
the east side of SH 82. Commercial uses exist along CR 110 and Frontage Road. The
intersection of SH 82 and CR 113 is an unsignalized full movement access.
Two additional access points to SH 82 of importance to the Project, although not utilized
by the Project, are located at Mirand Road and Spring Valley Road (CR 114/154), both
located north of the Project Site. The closest major access to SH 82 south of the Project
Site occurs at Diamond A Ranch Road at Aspen Glen, nearly two miles south of the
Project Site.
The intersection of CR 114/154 and SH 82 is a full movement signalized intersection with
designated left turn lanes. On the west side of the intersection is a small park–n‐ride lot
for the transit stop that is located at the intersection. East of the intersection are
industrial and commercial uses. Marand Road is located near the northern tip of the
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Project Site and is a local 2 lane access roadway on the east side of SH 82, providing
access to industrial and commercial uses. Across SH 82 from Marand Road access exists
to a former restaurant site which is currently vacant. The access is unsignalized and full
movement.
SH 82 is one of two north-south connections between CR 114/154 and Carbondale. The
other north-south connection is CR 109. Only one east-west connection across the
Roaring Fork River is provided between CR 154 and Carbondale (SH 133). This
connection occurs on private roads through Aspen Glen along Golden Bear Drive,
Midland Loop, Bald Eagle Way, and Diamond A Ranch Road. CR 109 serves the areas
west of the Roaring Fork River between these points and SH 82 serves properties east of
the Roaring Fork River.
The RFC Conservation Easement located immediately west of the Project Site allows a
bridge connection across the Roaring Fork River near the northern most end of the
easement. Currently, all roads north and west of the Project that could feasibly connect
to connect to REC facilities are private roads.
Access to the site is generally limited to the locations specified unless new provisions
are made for access. Project analysis must consider the design of these locations.
Development may be limited by the ability of these access locations to meet Project
demands. Accommodations for access to the adjacent properties should be considered
by the development plan.
C. EASEMENTS
All recorded easements are identified on the ALTA (Series V01) and Existing Conditions
and Land Suitability Plan (Series EC01) of the Drawing Package. Easements of
significance, other than the RFTA access easements discussed in parts A and B of this
Section above, include
The Glenwood Ditch Easement (Book 1292, Page 61). The Glenwood
Ditch currently diverts water from the Roaring Fork River, south of the
Aspen Glen development, to be used for land irrigation. The ditch is
piped and enters the Project Site along the southeastern edge of the
Project Site paralleling the RFTA Right-of-Way until it reaches Cattle
Creek. From that point, it traverses the Project Site in a northwesterly
direction and exits the Project Site prior to discharging back to the
Roaring Fork River.
The RFTA Open Space Easement (Book 1143, Page 593, as amended
Book 1217, Page 593). The 50' open space easement about the RFTA
Right-of-Way, which forms the east edge of the Project Site. The open
space easement is a mitigation buffer for activities including rail and
recreational trail uses within the right-of-way. It requires the placement
of landscaping and berms within the area to limit impacts to RFTA
activities and protect RFTA's ability to utilize their right-of-way.
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The RFC Conservation Easement (Book 1171, Page 929). The RFC
Conservation Easement, while technically forming the western edge of
the Project Site and providing a protective buffer along Cattle Creek, has
conditions and restrictions concerning construction activities and
landscaping that extend onto the Project Site.
An access easement (Book 1217, Page 610) to a property located west
of the Project Site. The easement provides access through the Project
Site across all roads to a property located west of the western most
edge of the Project Site.
Easement conditions must be included or integrated into any development plan. Where
the conditions associated with an easement cannot be met, the easement must be
modified, as appropriate.
D. TOPOGRAPHY AND SLOPE
The existing topography in the area is shown by the contour lines and steep slopes by
shading on the Existing Conditions/Land Suitability Plan, Series EC01 of the Drawing
Package. These contours represent the post-grading contours associated with grading
activities conducted by Bair Chase in 2005 as part of the Sanders Ranch PUD. As
discussed in the Geotechnical Engineering Study (Appendix J of the Impact Report), the
proposed 160 acre development area is located mostly on nearly level river terraces
that stand between about 50 to 80 feet above the Roaring Fork River. The terraces have
an average down-valley slope of less than one percent. Steep escarpments separate the
original terrace levels. These escarpments typically have slopes of up to 60 percent. The
escarpments between some terrace levels were obliterated during previous grading.
The current topography is significantly modified due to past grading, and nearly 80 years
of agricultural activities even before the most recent development activities.
E. NATURAL FEATURES
The 160 acre Project Site is located mostly on nearly level river terraces that stand
between about 50 to 80 feet above the Roaring Fork River. Steep escarpments exist
along the western edge of the Project Site and to a lesser extent along portions of Cattle
Creek and generally form the boundary between the RFC Conservation Easement and
the Project Site.
Wetlands exist along both Cattle Creek and the Roaring Fork River. Wetlands do not
generally extend off the RFC Conservation Easement onto the Project Site except in very
small pockets at the southern end of the site and along portions of Cattle Creek. No
wetlands are present on the upper or mid-level terraces within the Project Site.
Few other natural features exist on the Project Site. During the past 80 years or so, this
site was used as a cattle ranch, and the broad, flat terraces were irrigated pastureland.
During the summer of 2005, the Project Site was graded for the Sanders Ranch PUD.
Midway through grading, the project was terminated, which left the majority of the
Project Site with a cobbly surface. Topsoil was salvaged by this early grading process and
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stored in large piles on the property. The Existing Condition and Land Suitability Map,
Series EC01 of the Drawing Package show the areas of disturbance, soil stockpiles, and
vegetative cover on the Project Site.
The Project design should consider the pre-grading site conditions and whether terrace
conditions can or should be restored to some degree.
F. DRAINAGE FEATURES
The Roaring Fork River flows from the south to north just west of the Project Site
through the RFC Conservation Easement. The Roaring Fork River is a large perennial
river with a very large drainage basin to the south. The 160 acre Project Site is located
mostly on nearly level river terraces that stand between about 50 to 80 feet above the
Roaring Fork River.
Cattle Creek crosses through the Project Site from east to west and roughly divides the
property in half. Cattle Creek is a moderate sized perennial stream with a large drainage
basin to the east. Cattle Creek joins the Roaring Fork River about mid-way along the
western edge of the Project Site.
Small alluvial fans are present on the terrace surfaces in the eastern part of Project Site.
The upper parts of all of these fans have been removed by grading for Highway 82 and
development to the east of the highway. The fans developed at the mouths of small
drainage basins on the eastern side of the Roaring Fork River Valley. These basins
support ephemeral streams that only flow following heavy rainfall and snowmelt.
Lakes or ponds were excavated on the Project Site as golf features as part of the
proposed Sanders Ranch PUD but never completed, and do not hold water.
The site drainage has been disrupted. Careful consideration of impacts to major
drainage should be considered in Project design and layout.
G. WATER
The following is drawn from the letter report prepared by Water Resources Engineer
Michael J. Erion, P.E. of Resources Engineering, Inc. [Appendix B of the Water Supply
Report ("Resources Engineering Report")] which presents the water rights and water
supply plan for the Project. Water appears to be available to support up to 1200 EQRs
worth of development and irrigation of 260 acres.
1. POTABLE WATER SUPPLY AND SOURCE
As documented in the Resources Engineering Report, the legal water supply for
the potable water system is based on the water court decrees in Case No.
01CW187, 07CW164 (pending) and 08CW198 (pending). In Case No. 01 CW187,
a legal water supply for 349.55 EQR's and 3 acres of irrigation was adjudicated.
The decree utilizes 62.6 acre feet of Basalt Water Conservancy District ("BWCD")
contract water for diversion at the RFWSD Aspen Glen Well Nos. 1-7, Coryell
Ranch Well Nos. 1-14, and the Coryell Ranch Roaring Fork Diversion. The
pending decree in Case No. 07CW164 provides for an additional 850.45 EQR's
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and 4 acres of irrigation. Points of diversion for include RFWSD at the Robertson
Ditch, Posy Pump and Pipeline, RBC Well Field, and the RBC Roaring Fork
Diversion. The pending decree in Case No. 08CW198 provides for the 349.55
EQRs and 3 acres of irrigation to be diverted at the additional points of diversion
identified in Case No. 07CW164. River Edge Colorado has amended BWCD
Contract No. 381 for a total of 75.4 acre feet as required for all three water
court decrees. The current Project demands 375 of the 1200 EQRs adjudicated
or in pending decrees.
The potable water supply could be provided by the RFWSD alluvial wells located
in the Aspen Glen and Coryell Ranch subdivision if the Project is served by the
RFWSD, and surface diversions from the Roaring Fork River using the Robertson
Ditch Rose Ranch Enlargement, Posy Pump and Pipeline (Iron Bridge
Subdivision), or the RBC Roaring Fork Diversion (River Edge Colorado). The RBC
Roaring Fork Diversion (River Edge Colorado) would be utilized if the Project is
served by an alternative system as described in the Water Supply Report.
Resource Engineering, Inc. notes that the yield of the physical water supply from
the RFWSD alluvial wells and from the Roaring Fork River are not affected by dry
year hydrologic conditions.
2. IRRIGATION WATER
Also as documented in the Resources Engineering Report, the Glenwood Ditch is
decreed for 50 cfs for irrigation uses and Staton Ditch is decreed for 5.18 cfs for
irrigation uses. The water court Case No. W-2206 for the Unocal Sanders Ranch
determined that the historic consumptive use is 439 acre feet on 260 irrigated
acres of which the Project Site represents approximately 150 acres of the total
irrigated areas. CI also holds reliable irrigation water rights in the Glenwood
Ditch (12.23 c.f.s.), represented by 367 shares of capital stock in the Thompson
Glen Irrigation Company, and in the Staton Ditch (4.69 c.f.s.).
The physical source of water will be from the Roaring Fork River via diversion
into the Glenwood Ditch and from Cattle Creek via diversion into the Staton
Ditch. Historically, the Glenwood Ditch has had a full water supply, even in
critically dry years. The Project's buildout irrigation use is estimated at
significantly less than the overall irrigation water available to the Project. Water
delivery will utilize a raw water distribution system feed by the Glenwood Ditch
and Cattle Creek.
3. IRRIGATION WATER RETURN FLOWS
The fields associated with the Project Site were flood irrigated when under
production. Return flows entered Cattle Creek and the Roaring Fork River as
evidenced by piping along the steep terrace escarpment (further discussed
under Hazards, Section J) and the location of cottonwoods and other vegetation
along the western edge of the Project Site.
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H. FLOODPLAINS
The floodplains associated with both the Roaring Fork River and Cattle Creek generally
do not extend onto the Project Site except along small portions of Cattle Creek. These
areas should be avoided by development and encroachments should be generally
limited to facilities that cannot avoid areas subject to flooding such as bridge structures
and utility crossings. The floodplains are shown on the Existing Conditions/Land
Suitability Plan, Series EC01 of the Drawing Package.
I. SOILS
Hepworth-Pawlak Geotechnical, Inc. (HP Geotech) completed an assessment of soils and
geologic conditions including the identification of geologic hazards for the REC PUD in
November 2010. The following discussion concerning the soil conditions is summarized
from the Geotechnical Engineering Study (Appendix J of the Impact Report).
The main landforms at the Project Site related to the site's surficial materials include (1)
post-glacial alluvial terraces along the Roaring Fork River and Cattle Creek, (2) Pinedale
glacial outwash terraces along the Roaring Fork River and related alluvial terraces along
Cattle Creek, and (3) coalescing alluvial fans. A small part of the Project Site is located on
the post-glacial alluvial terraces and the remaining area sits on the Pinedale glacial
outwash terraces. An alluvial fan overlays a small area near the southern end of the
Project Site.
The topsoil was stripped from most of the Project Site and stockpiled in 2005 by Bair
Chase in association with the Sanders Ranch PUD approved by Garfield County. The
areas stripped of topsoil and stockpile sites are shown on the Existing Conditions/Land
Suitability Plan, Series EC01 in the Drawing Package. The previous grading consists of
both cut and fill areas. The fill areas are mostly composed of coarse-grained terrace
alluvium. The terrace topsoil and upper fine-grained deposits were separated during
grading and were placed in the soil stockpiles. The character of the coarse- and fine-
grained terrace alluvium is described in the Pinedale Terraces as described in the
Geotechnical Engineering Study.
The post-glacial terraces are located as two terraces. The lower terrace stands about 5
feet above the river and the higher terrace stands about 13 feet above the river. The
alluvium is described as a clast-supported deposit of silty sand with occasional bouldery,
pebble and cobble gravel interbedded and often overlain by sandy silt and silty sand.
Shallow groundwater is expected to be present in these areas. A small part of the
southern part of the Project Site is located on the upper terrace. Elsewhere the Project
Site is located on the higher Pinedale terraces.
The Pinedale outwash terraces along the Roaring Fork River and the associated Cattle
Creek terraces occur in several levels that formed at different periods. Grading in 2005
removed all of the mid level terraces. The alluvium under the Pinedale terraces
associated with the Roaring Fork River and Cattle Creek are a clast-supported deposit of
rounded gravel, cobbles and boulders in a silty sand matrix. Pedogenetic soil profiles are
well developed in the Pinedale terraces. This indicates these surfaces have been stable
with respect to erosion and deposition for over about 5,000 years.
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With respect to disturbed soils and revegetation, Rocky Mountain Ecological Services in
Appendix A of the Reclamation Plan (Appendix U) have noted that "soils have been
stockpiled for upwards of 5 years and the soil microbial populations, nutrient levels, and
mycorrhizal fungi populations will be highly altered." This could result in difficulty in
reestablishing native vegetation.
Careful consideration of soil erosion and surface water control measures to control
water infiltration and concentrated flows since the surficial materials are susceptible to
piping. Also with respect to disturbed soils and revegetation, Rocky Mountain Ecological
Services in Appendix A of the Reclamation Plan (Appendix U) have noted that they
recommend that soil samples be sent to Colorado State University for nutrient analyses
prior to the revegetation activities and appropriate treatments be undertaken as part of
pre-development reclamation to enhance potential success of revegetation efforts. The
most cost effective means of influencing mycorrhizal populations on large projects is to
provide suitable soil conditions such as using soils with higher soil organic matter and
avoiding heavy fertilization. The stockpiled topsoils on the property may or may not
have adequate levels of organic matter and may also require enrichment.
J. HAZARDS
HP Geotech completed an assessment of geologic conditions including the identification
of geologic hazards for the REC PUD in November 2010. The Geotechnical Engineering
Study is included in Appendix J of the Impact Report. Five primary hazards affecting the
Project Site were identified in the Geotechnical Engineering Study. These hazards
include evaporite sink holes, steep terrace escarpments, active stream bank erosion,
debris flows and floods, and earthquakes. The following key information and
considerations are drawn from in the study. Important hazard areas are identified on
Existing Conditions/Land Suitability Plan, EC01 Series of the Drawing Package.
1. EVAPORITE SINK HOLES
HP Geotech notes that the near surface formation rock in the area is the Eagle
Valley Evaporite. The evaporite between Carbondale and about 3 miles south of
Glenwood Springs is part of the Roaring Fork diapir which coincides with the
Grand Hogback monocline that marks the western limit of the Carbondale
evaporite collapse center. The Carbondale evaporite collapse center is the
western of two regional evaporite collapse centers present in the western
Colorado evaporite region. As much as 4,000 feet of regional ground subsidence
is believed to have occurred during the past 10 million years as a result of
dissolution and flowage of evaporite from beneath the region. HP Geotech
notes that it is uncertain if the regional subsidence and evaporite deformation
along the Roaring Fork diapir are still an active geomorphic process or if
evaporite deformations have stopped. If still active, present deformations are
likely occurring at rates similar to past long-term rates of between 0.5 and 1.6
inches per 100 years.
HP Geotech identified nine general sinkhole areas in the field and on aerial
photographs in and close to the Project Site. These locations are identified on
the Existing Conditions/Land Suitability Plan, EC01 Series of the Drawing
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Package. Evaporite sinkholes in western Colorado are typically 10- to 50-foot
diameter, circular depressions at the ground surface that result from upward
caving of a soil rubble pipe to the ground surface. The soil rubble pipe is formed
by subsurface erosion (piping) of near surface soils into subsurface voids.
Sinkhole development is still an active geomorphic process. The Project Site is
potentially subject to new sinkhole development or reactivation of existing
sinkholes as is consistent with the regional geology. Appropriate investigations
and mitigation will be necessary as part of design. Areas where sinkholes have
been identified should be avoided by development where practical as opposed
to being mitigated. Generally, mitigation methods are available to address the
issues associated with these hazards.
2. STEEP TERRACE ESCARPMENTS
Steep terrace escarpments that commonly have slopes of about 60 percent and
vary from 40 to 80 feet high are present along the Roaring Fork River and the
lower reaches of Cattle Creek. These escarpments are potentially unstable and
in some cases have been further destabilized due to piping associated with
irrigation water from the previous agricultural activities on the Project Site. The
escarpments are located along the western most property line and encroach
into the RFC Conservation Easement. These areas can contribute to sediment
production during rain and flood events or in association with excessive
irrigation. As with identified sinkholes, these areas should generally be avoided
by development and mitigation measures may be appropriate to implement as a
means of reducing deformation.
3. ACTIVE STREAM BANK EROSION
Active stream bank erosion during high flood flow is occurring along the Roaring
Fork River and Cattle Creek within the RFC Conservation Easement. In several
areas, where these streams flow along the base of the steep terrace
escarpments they can result in further destabilizing the steep terrace
escarpments. These areas contribute to sediment production during rain and
flood event and can result in more catastrophic inputs to the Roaring Fork River
when failures occur. These areas all lie outside the boundaries of the Project
Site. However, correction of these areas could be beneficial in stabilizing steep
escarpments and reducing further deformation or failure.
4. DEBRIS FLOW AND FLOODS
HP Geotech noted that coalescing alluvial fans developed at the mouth of the
numerous, small drainage basins on the east side of the Roaring Fork River
Valley where the ephemeral streams in these basins discharge on terrace
surfaces. Before construction of SH 82 and development to the east of the
highway, the alluvial fan formed a continuous apron at the terrace-valley side
transition. Most of the upper parts of the fans have been removed by grading
for these facilities. Swell-consolidation tests show that the deposits do not have
a high collapse potential (settlement after wetting under a constant load) and
are moderately compressible under increased loading after wetting. This
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River Edge Colorado, Garfield County, Colorado
14
indicates that the fans are geologically young landforms and are still potential
sites of debris flow and flood deposition provided flows are able to reach these
areas prior to deposition at SH 82 and the RFTA right-of-way benches. These
areas should generally be avoided by development. However, if development is
proposed, mitigation measures are generally available to address these hazards.
5. EARTHQUAKES
HP Geotech details the faults present in the vicinity of the Project. They
conclude that geologically young faults related to evaporite tectonics are
present in the Carbondale evaporite collapse center in the vicinity of the Project
Site, but considering the nature of evaporite tectonics, these faults are not
considered capable of generating large earthquakes.
The closest geologically young faults considered capable of generating large
earthquakes are located in the Rio Grande rift between 62 and 67 miles east of
the Project Site. For firm rock sites with shear wave velocities of 2,500 fps in the
upper 100 feet, the U. S. Geological Survey 2002 National Seismic Hazard Map
indicates that a peak ground acceleration of 0.06g has a 10% exceedance
probability for a 50 year exposure time and a peak ground acceleration of 0.22g
has a 2% exceedance probability for a 50 year exposure time at the Project Site.
This corresponds to a statistical recurrence time of about 500 years and 2,500
years, respectively. HP again concludes that at these distances large
earthquakes on the two closest geologically young fault zones should not
produce strong ground shaking at the Project Site. HP concludes that
earthquake risk is consistent with other areas of the Roaring Fork Valley. Limited
risks to development are associated with earthquakes and mitigation measures
are generally determined to be unnecessary.
6. RADIATION
The Project Site lies in Region 8 part of the Colorado Plateau Province and
determined by the Environmental Protection Agency (EPA) to have moderate
radon potential (Map of Radon Zones: Colorado, EPA, September 1993, pg. iii-6).
In accordance with this report, the Colorado Plateau Province in Region 8 has a
band of high radon potential and a core of moderate radon potential. The band
of high radon potential consists largely of: (1) the Uravan Mineral Belt, a
uranium mining district, on the east; (2) the Uinta Basin, which contains
uranium-bearing Tertiary rocks, on the north; and (3) Tertiary volcanic rocks,
which have a high aeroradiometric signature, on the west. The moderate radon
potential zone located in the interior part of the province, within which the
Project Site is located, is underlain primarily by sedimentary rocks, including
sandstone, limestone, and shale, which have a low aeroradiometric signature.
County average screening indoor radon levels in the Colorado Plateau are
mostly greater than 2 pCi/L (EPA). However, indoor radon levels within the area
surrounding the Project Site are often below this level (EPA). In addition, the
Geotechnical Engineering Study concludes "the project site is not located on
geologic deposits that would be expected to have high concentration of
radioactive minerals" (Geotechnical Engineering Study, pg. 18).
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River Edge Colorado, Garfield County, Colorado
15
K. NATURAL HABITAT
Rocky Mountain Ecological Services prepared the Wildlife & Vegetation Assessment
Report ("Wildlife Report") dated December 2010 (Appendix K Impact Report). The
following information is drawn from that report. The habitat areas and vegetation as
depicted in the report are identified on Existing Conditions/Land Suitability Plan, EC01
Series of the Drawing Package.
1. VEGETATIVE COVER
As noted in the Wildlife & Vegetation Assessment Report (Appendix K of the
Impact Report), the current state of the vegetative cover over much of the
Project Site reflects several recent and historical impacts. While the area within
the RFC Conservation Easement along the Roaring Fork River is still dominated
by native woody species, much of the upland portion of the Project Site was
cleared of native vegetation around 100 years ago to plant non–native hay
grasses and/or provide for livestock and farming activities. The riparian
vegetation along Cattle Creek itself is highly altered. The impacts from past year-
round grazing practices are also still apparent as very little woody vegetation
occurs along much of Cattle Creek on the upper benches. Any remaining
pockets of native sagebrush shrublands also show little species diversity. The
introduction of noxious weed species along the Roaring Fork River’s riparian
corridor probably occurred during the agricultural operation of the area as well.
In 2005, the upland topsoils on Project Site were removed and salvaged with
heavy equipment and most of the property was re-contoured and taken down
to subsoil in preparation for development. Partway through these efforts, the
development was abandon. The acres of newly denuded, very cobbly subsoils
were colonized by ruderal, non-native weed species such as white sweetclover
(Melilotis alba), flixweed (Descurainia Sophia) and Russian thistle (Salsola
collina). Several noxious weeds also took residency, including kochia (Bassia
sieversiana), common tansy (Tanacetum vulgare), plumeless thistle (Carduus
acanthoides), Russian knapweed (Acroptilon repens), cheatgrass (Anisantha
tectorum), houndstongue (Cynoglossum officinale), and scotch thistle
(Onopordum acanthium). The graded areas are essentially devoid of vegetation
except for weeds. The Existing Condition and Land Suitability Map, Series EC01
of the Drawing Package show the areas of disturbance, soil stockpiles, and
vegetative cover on the Project Site.
Vegetation outside the previously irrigated and graded areas is mostly sage, oak
and other brush on the fans and terrace escarpments. Cottonwood trees, grass
and willows are present on the lower terraces adjacent to the Roaring Fork River
and Cattle Creek. As noted in the Wildlife & Vegetation Assessment Report
(Appendix K of the Impact Analysis), historically, the site was likely dominated
by basin sagebrush flats (Artemisia tridentata var. tridentata), with patches of
mountain sagebrush (Artemisia tridentata var. pauciflora).
Overall, vegetative cover is of poor quality, limited diversity, and highly
impacted by previous agricultural and development activities across most the
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River Edge Colorado, Garfield County, Colorado
16
Project Site. Reclamation, revegetation, and noxious weed control measures
could have some benefit to the habitat areas. However, as noted below, other
constraints at the Project Site would still result in marginalized use of the
habitat areas by most species.
2. HABITAT AREAS AND GENERAL WILDLIFE USE
The Project Site and adjacent lands are located in two habitat areas described
by Rocky Mountain Ecological Services. These include an Upland Habitat area
and Riparian Habitat area. The Upland Habitat area constitutes a majority of the
area being utilized by the Project. The Riparian Habitat area is generally located
adjacent to the Project Site in the RFC Conservation Easement but does enter
the Project Site in small areas. The following description is extracted from the
Wildlife & Vegetation Assessment Report (pgs. 8-9, 12-13, and 39).
The Upland Habitat, which constitutes a majority of the Project Site, is highly
damaged from over 80 years of agricultural use and grading for the Bair Chase
project in 2005. During this process, topsoils on the property were salvaged and
stored in large stockpiles on the property. These topsoil stockpiles are currently
dominated with a variety of ruderal early seral plant species. CI began treating
noxious weeds in 2007, but some noxious weeds persist. CI has also began
seeding topsoil stockpiles and graded areas with a temporary seed mix,
consisting of native grasses and annual grasses to increase soil cover, reduce
erosion, and help reclaim areas from weeds. The graded areas are essentially
bare, and have very low aerial cover of plant species. Current vegetation cover
on the graded areas is approximately 5 to 15%, with the densest vegetation
being stands of cheatgrass and kochia. Moderate to large cobble-sized material
dominate the surface soils stratum.
Rocky Mountain Ecological Services notes that wildlife use of the Upland Habitat
is currently limited by vegetation types and cover. The most commonly
observed species on the property is the Wyoming ground squirrel
(Spermophilus elegans), which has colonies near the railroad grade. The
presence of this squirrel likely attracts incidental foraging by great-horned owls,
red-tailed hawk, red fox, gray fox, and coyote; however predator use of the
property is likely incidental, as predators would likely prefer to hunt and forage
on surrounding higher quality habitats. Bird use in the uplands is limited to a
few species that can utilize the existing habitat conditions. This is generally
limited to mourning dove, meadowlark and mountain bluebird. However, many
other species may be observed within the uplands as they pass through the
property to other more suitable habitats in the area.
The Riparian Habitat areas along the Roaring Fork River and lower Cattle Creek,
largely outside the Project Site, are dominated by mixed deciduous overstories,
with understories dominated by noxious weeds and non-native agricultural
grasses. Overstories are dominated by narrowleaf cottonwood (Populus
angustifolia), silver buffaloberry (Shepherdia argentea), river birch (Betula
fontinalis), alder (Alnus incana) hawthorne (Cratagus rivularis & C. saligna),
boxelder (Acer negundo), Rocky Mountain juniper (Sabina osteosperma), and
Land Suitability Analysis
River Edge Colorado, Garfield County, Colorado
17
intermittent ponderosa pine (Pinus ponderosa). Many of the cottonwoods were
established in association with the historic flood irrigation practices. As a result,
many of the cottonwood trees in the area have become decadent, and are dying
off due to the cessation of flood irrigation and use of more controlled forms of
irrigation. Riparian understory vegetation is dominated by canarygrass
(Phalaroides arundinacea), and agricultural cultivars such as orchard grass
(Dactylis glomerata), smooth brome (Bromis inermis), timothy (Phleum
pratense), and native shrubs such as skunkbrush (Rhus aromatica sbsp trilobata)
and wild rose (Rosa woodsii). Noxious weeds include common tansy, field
bindweed, Canada thistle (Cirsium arvense), scotch thistle, plumeless thistle,
common mullein (Verbascum thapsis), and Russian olive trees (Elaeagnus
angustifolia). Cattle Creek supports canarygrass along its entire length. The
general conditions of the understory in riparian systems along lower Cattle
Creek and along the Roaring Fork River are very poor due to high levels of
disturbance resulting in noxious weeds and a prevalence of aggressive,
agricultural grasses and canarygrass.
During wetland delineations in July of 2010, the Federally Threatened Ute
ladies-tresses orchid (Spiranthes diluvialis) was identified in the inundation zone
adjacent to the Roaring Fork River. The Project Site does not have any orchid
populations or habitats.
Cattle Creek was heavily impacted in the past by grazing practices. The upper
section of Cattle Creek crossing the Project Site is dominated by non-native
species, including common tansy and canary reed-grass. The current habitat
condition is poor with little habitat diversity. Most species observed in this area
were upland bird species. Common riparian bird species are lacking due to the
paucity of structural diversity of habitats. Some nighttime use by deer, elk, and
other species is likely.
Lower Cattle Creek (near the confluence with the Roaring Fork) is of a better
habitat quality and condition than the upper section. The lower section includes
various shrub and tree plant species and more native vegetation. The
understory vegetation is dominated by graminoid species, which somewhat
diminishes the habitat conditions. More wildlife species utilize this area than the
upper section due to widespread wetland habitats, and the structural diversity
provided by taller shrubs (e.g., silver buffaloberry [Shepherdia argenteus]).
The Roaring Fork River supports diverse riparian woodlands and shrublands.
Most of the trees along the river are somewhat decadent, and there is a general
lack of younger trees along the river. A couple of the larger ponderosa pine
(Pinus ponderosa) trees along the river are currently providing nesting for a
small to moderately sized Great Blue Heron rookery. One of the three rookery
trees fell down into the Roaring Fork in the spring of 2009 due to high
springtime flows and bank scour on the western bank. The riparian habitats
along the river provide habitat for a number of bird species, as well as habitat
for many mammal species.
Land Suitability Analysis
River Edge Colorado, Garfield County, Colorado
18
Overall, the Upland Habitat areas that make up a majority f the site are in very
poor condition and only provide for marginal utilization by animal species.
Lower areas of the site adjacent to the RFC Conservation Easement could be
utilized as buffers to conserve use of the Riparian Habitat areas along the
Roaring Fork River. Cattle Creek utilization is highly impacted by the Elk fencing
placed along SH 82 which has limited movement through the Project Site
between the east and west sides of SH 82.
3. SPECIFIC SPECIES OF SPECIAL IMPORTANCE
Species of key consideration and discussion in the Wildlife & Vegetation
Assessment Report include mule deer, elk, bald eagle, heron, and Lewis's
woodpecker. In addition, the Federally Threatened Ute ladies-tresses orchid
(Spiranthes diluvialis) was identified in the inundation zone adjacent to the
Roaring Fork River as discussed previously.
No critical wildlife habitat areas were identified within the Project Site by Rocky
Mountain Ecological Services. However, five species subject to the critical
wildlife habitat definition detailed in the Impact Report are known to utilize the
Project Site. These species include the mule deer, elk, bald eagle, heron and
Lewis's woodpecker.
According to the Wildlife & Vegetation Assessment Report, the Project Site is
within Elk Winter Range. Elk Severe Winter Range lies east of SH 82 (Wildlife &
Vegetation Assessment Report, pg. 35). The Project Site is also located between
Mule Deer Winter Range located west of the Roaring Fork River and Mule Deer
Severe Winter Range located east of SH 82, but the Project Site is not located
within either of these ranges (Wildlife & Vegetation Assessment Report, pg. 17).
As a result, none of the Project Site is classified as an Elk or Mule Deer habitat
type considered to be critical.
The Project Site supports low-density year-round levels of mule deer. The
adjacent areas within the RFC Conservation Easement near the Roaring Fork
River which contain shrubby vegetation, would likely meet criteria as Mule Deer
Winter Range (Wildlife & Vegetation Assessment Report, pg. 17). Deer do utilize
the flat terraces despite the lack of quality vegetation, but there is definitely
more deer within the RFC Conservation Easement. The use of Rio Grande Trail
has likely deterred deer use of areas within 100 meters of the trail (Wildlife &
Vegetation Assessment Report pg. 17).
Elk primarily use the Project Site as a loafing area since the property only
supports marginal foraging opportunities. The Project Site supports reasonable
numbers of elk during the winter months. Rocky Mountain Ecological Services
notes that during the past few winters, due to very marginal grazing
opportunities, many of the elk likely moved to other areas for feeding, but
reasonably high numbers of elk persist on the Project Site through the winter,
likely utilizing the property as a loafing area during the daytime hours, or when
snows covered foraging opportunities on other properties (Wildlife &
Vegetation Assessment Report, pg 35). The Rio Grande Trail was opened for
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River Edge Colorado, Garfield County, Colorado
19
winter use during 2009. The trail has introduced daily walkers, dog walkers, and
sometimes bicyclists and cross country skiers through the middle of this
property. The opening of the Rio Grande Trail combined with the construction
of the elk fence along SH-82 has noticeably reduced the number of elk observed
wintering on the REC property (Wildlife & Vegetation Assessment Report, pg
35).
As previously noted, a heron rookery ("heronry") is present in the RFC
Conservation Easement adjacent to the Project Site. Heron generally arrive in
the valley in mid March. At this time, 2 ponderosa pine trees comprise the
heronry (a third tree fell down in 2009 due to bank erosion on the Roaring Fork
River), with the tree on the east bank of the Roaring Fork River having
approximately 10 nests, and the tree on the western side of the river having 15
nests (Wildlife & Vegetation Assessment Report, pg. 41). This heronry is fairly
productive given the limited size of area it occupies, when compared to the
heronry at Rock Bottom Ranch (9 nests in 2008) and Woody Creek (15 nests
in2008) (Wildlife & Vegetation Assessment Report, pg. 41). The heronry is
located adjacent to the Project Site and meets the definition of critical habitat.
The heronry has been located by a pair of Golden Eagles, who killed a majority
of the young in 2010. This could lead to abandonment in future years, as has
been the case in other locations in the region.
With respect to the bald eagle, the closest bald eagle nest site is located on the
Aspen Glen subdivision. Nesting at the site has been successful for the past 5
years. The Wildlife Report finds that bald eagles primarily use the RFC
Conservation Easement adjacent to the Project Site for roosting on trees near
the river and hunting for fish. The Aspen Glen bald eagles are believed to be the
only bald eagles utilizing the area (Wildlife & Vegetation Assessment Report, pg.
47). The bald eagle utilizes areas adjacent to the Project Site for roosting which
is considered a component of the critical habitat.
Finally, Rocky Mountain Ecological Services notes that the Project Site and RFC
Conservation Easement are home to the Lewis's Woodpecker. Lewis’s
Woodpeckers are migratory, arriving in breeding and summer ranges in May
and departing again in early to mid-September. Lewis’s Woodpeckers from the
Project Site, likely migrate westward towards the lower Uncompahgre,
Gunnison, and Colorado River valleys, but some birds may migrate as far south
as northern Mexico. Their migration is slow and is diurnal. Important aspects of
breeding habitat include an open canopy, a brushy understory offering ground
cover, dead or downed woody material, available perches, and abundant
insects. Three principal habitats are open ponderosa pine forest; open riparian
woodland dominated by cottonwood; and logged or burned pine forest (Wildlife
& Vegetation Assessment Report, pg. 48). The Lewis's Woodpecker is
considered by the local United State Forest Service ("USFS") as a sensitive
species. The habitat available adjacent to the Project Site is not considered
critical habitat pursuant to the applicable definition.
Land Suitability Analysis
River Edge Colorado, Garfield County, Colorado
20
Overall, the wildlife influences at the site are important considerations but
limited with respect to overall potential impacts to the species of importance.
Providing open space buffers between development areas and RFC
Conservation Easement could be beneficial to continued utilization of the RFC
Conservation Easement by all species. Elk fencing along SH 82, the lack of
forage, and use of the Rio Grande Trail has significantly reduced use of the
Project Site by Elk and Mule Deer over the past several years. Upland Habitat
areas which make up a majority of the Project Site are considered poor quality
habitat for Elk and Mule Deer and generally only utilized as loafing areas. Buffer
areas for heron should be considered along with other protective controls when
developing the Project Site as outline in the Wildlife Report (pg. 50-53).
L. RESOURCE AREAS
Maps and records on file at the State Office of Archaeology and Historic Preservation
Office ("SHPO") were checked for any recorded historic and/or prehistoric sites in or
immediately around the Project Site. There are no recorded sites inside the Project Site,
or in the immediate vicinity. A majority of the Project Site was used for agricultural
purposes for nearly 80 years and was regraded in 2005. As such, any resources that may
have been present are likely to have been removed or significantly damaged beyond
repair as part of these activities.
The barn associated with the old ranch was removed from the Project Site in 2005. The
barn may have had important architectural attributes and been viewed, by some, as
significant to the valley's character. However, no remnants exist today. At present, the
only clearly identifiable potential historic resource located near the Project Site is a
trestle carrying the RFTA trail over Cattle Creek within the RFTA right-of-way. Although
the trestle is not listed as an historic resource by the SHPO in their list of rail and historic
resources, the trestle clearly has several characteristics that are important and might
meet the general standards for preservation. The resource is not located on the Project
Site but can be viewed from the Project Site and SH 82.
APPENDIX A: VICINITY MAP AND PROJECT SITE LOCATION
App. A-1
12/01/10VICINITY MAPExhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.5325App. A-2
Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. A-3
Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. A-4
Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. A-5
Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. A-6
Land Suitability Analysis
River Edge Colorado, Garfield County, Colorado
APPENDIX B: TRANSPORTATION SYSTEM MAP
App. B-1
Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. B-2