HomeMy WebLinkAbout3.03 Geologic Hazards Rpt
Article 4-203.G.4
Geologic and Soils Hazard
Report
Ursa Operating Company LLC
Speakman A Injection Well
OA Project No. 013-3151
NATURAL AND GEOLOGIC HAZARDS
ASSESSMENT REPORT
URSA OPERATING COMPANY
SPEAKMAN A CLASS II UIC WELL
NE ¼, SW 1/4 SECTION 24, T7S, R96W, 6TH P.M.
GARFIELD COUNTY, COLORADO
PREPARED FOR
URSA OPERATING COMPANY
1050 17TH STREET, SUITE 2400
RIFLE, COLORADO 81650
PREPARED BY
OLSSON ASSOCIATES
4690 TABLE MOUNTAIN DRIVE, SUITE 200
GOLDEN, COLORADO 80403
FEBRUARY 2014
PROJECT NO. 013-3151
Geologic Hazard Report i Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
Natural and Geologic Hazard Report Preface
Garfield County, Colorado, finalized the Land Use and Development Code (LUDC) with an
effective date of July 15, 2013. According to Section 7-108 Use of Land Subject to Natural
Hazards of the Garfield County LUDC “Land subject to identified Natural and Geologic Hazards,
such as falling rock, landslides, snow slides, mud flows, radiation, flooding, or high water tables,
shall not be developed unless it has been designed to eliminate or mitigate the potential effects
of hazardous site conditions as designed by a qualified professional engineer and as approved
by the County.”
The LUDC requires a Natural and Geologic Hazard Study be prepared by a qualified
professional geologist be submitted with a development plan or plat. The LUDC defines a
geologic hazard as “A geologic phenomenon that is so adverse to past, current, or foreseeable
construction or land use as to constitute a significant hazard to public health and safety or to
property.”
The LUDC defines a Hazard Area as “An area that contains or is directly affected by a geologic
hazard, including but not limited to the following types of areas.”
A. Avalanche Area. “A mass of snow or ice and other material that may become
incorporated therein as such mass moves rapidly down a Slope.”
B. Landslide Area. “An area with demonstrably active mass movement of rock and
soil where there is a distinct surface rupture or zone of weakness that separates
the landslide material from more stable underlying material.”
C. Mudflow Debris Area. “An area subject to rapid mud and debris movement or
deposit occurring after mobilization by heavy rainfall or snowmelt runoff. Such
areas are formed by successive episodes of deposition of mud and debris.”
D. Radioactive Area. “An area subject to various types of radiation emission from
radioactive minerals that occur in natural or manmade deposits of rock, soil, or
water.”
E. Potentially Unstable Soils. “An area of land identified as having soils that may
cause damage to structures, such as buildings and roadways, as a result of over
saturation or some other outside influence.”
According to the Garfield County LUDC Section 4-203 Description of Submittal Requirements,
the professional qualifications for preparation and certification of certain documents required by
this Code are as follows:
“Geologist. Geology reports shall be prepared by either a member of the American
Institute of Professional Geologists, a member of the Association of Engineering
Geologists, or a qualified geotechnical engineer licensed in the State of Colorado.”
Geologic Hazard Report ii Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
A search of the Colorado Department of Regulatory Agencies (DORA) Licensed Professionals
and Businesses indicates that Colorado licenses “professional engineers” and “engineer interns”
but does not appear to have a license specific to “geotechnical engineers.” Currently, the State
of Colorado does not require licensure or registration of geologists. Colorado Revised Statutes
do require that geologic reports be prepared or authorized by a professional geologist.
However, “Professional Geologist” is a term defined in Colorado Statutes.
The references for these Statutes are shown here:
34-1-201. Definitions. As used in this part 2, unless the context otherwise requires:
(1) “Geologist” means a person engaged in the practice of geology.
(2) “Geology” means the science which treats of the earth in general; the earth’s
processes and its history; investigation of the earth’s crust and the rocks and other
materials which compose it; and the applied science of utilizing knowledge of the
earth’s history, processes, constituent rocks, minerals, liquids, gases, and other
materials for the use of mankind.
(3) “Professional geologist” is a person who is a graduate of an institution of higher
education which is accredited by a regional or national accrediting agency, with a
minimum of thirty semester hours (forty-five quarter) hours of undergraduate or
graduate work in a field of geology and whose post baccalaureate training has been in
the field of geology with a specific record of an additional five years of geological
experience to include no more than two years of graduate work.
(4) 34-1-202. Reports containing geologic information. Any report required by law or by
rule and regulation, and prepared as a result of or based on a geologic study or on
geologic data, or which contains information relating to geology, as defined in Section
34-1-201 (2), and which is to be presented for any state agency, political subdivision
of the state, or recognized state or local board or commission, shall be prepared or
approved by a professional geologist as defined in Section 34-1-201(3).
Geologic Hazard Report iii Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
Professional Geologist Certification
By means of this certification, I attest that:
- I am qualified to prepare a Natural and Geologic Hazard Study in accordance with
the provisions of Section 7-207 of the Garfield County LUDC, and that I am a
member of the American Institute of Professional Geologists per LUDC 4-203.
- Although I have not visited the proposed Site, I am familiar with the geology and
have performed field work in the area of the proposed Ursa Operating Company LLC
Speakman Pad A UIC Well located in the NE ¼ SW ¼ Section 24, Township 7
South, Range 96 West, 6th Principal Meridian in Garfield County, Colorado.
- Although the Colorado Geological Survey does not currently have a licensing or
registration program for professional geologists practicing in the state of Colorado,
there are requirements within local and State statutes that require that geologic
reports be prepared by a professional geologist. I attest that I meet the requirements
of the Colorado Geological Survey’s definition of a professional geologist having
completed and met the educational requirements of the Colorado Geological Survey
definition.
- I am a licensed Professional Geologist and Professional Geoscientist in other States,
including Utah and Wyoming which do have licensing programs for professional
geologists.
- I have reviewed published geologic maps and reports applicable to this area and
have considered the implications of these conditions in the context of the proposed
development.
- This report has been prepared in accordance with good scientific principles and
engineering practices including consideration of applicable industry standards, and
with consideration of the requirements of the National Association of State Boards of
Geology. The conclusions and recommendations contained in this report are based
on information available and known to me at the time of this report. Good scientific
principles and standard engineering practices were taken into consideration to in
arriving at the conclusions and recommendations made in this report.
James W. Hix
Senior Geologist
Date: __02/06/2014____________
Note: The PG’s certification does not relieve the owner/operator of the facility of the duty to review this report or fully implementing
the recommendations in accordance with all applicable Federal, State, and local requirements in order to achieve the desired goals
or objectives.
Geologic Hazard Report iv Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
TABLE OF CONTENTS
Natural and Geologic Hazard Report Preface ............................................................................... i
Professional Geologist Certification ............................................................................................. iii
TABLE OF CONTENTS ............................................................................................................... iv
FIGURES ..................................................................................................................................... iv
1.0 EXECUTIVE SUMMARY ..................................................................................................... 1
2.0 GENERAL SITE LOCATION AND BACKGROUND ............................................................ 2
2.1 Project and Site Description ............................................................................................ 2
2.2 Structural Geology ........................................................................................................... 2
2.3 Site Geology .................................................................................................................... 3
2.4 Soil ................................................................................................................................... 3
2.5 Hydrologic Setting ............................................................................................................ 4
2.6 Aquifers ............................................................................................................................ 4
3.0 NATURAL AND GEOLOGIC HAZARD ASSESSMENT ...................................................... 5
3.1 Utilities ............................................................................................................................. 5
3.2 Avalanche Hazard Area ................................................................................................... 5
3.3 Landslide Areas or Potential Landslide Hazard Areas .................................................... 5
3.4 Rockfall Areas .................................................................................................................. 6
3.5 Alluvial Fan Hazard Areas ............................................................................................... 6
3.6 Unstable or Potentially Unstable Slopes .......................................................................... 6
3.7 Corrosive or Expansive Soils and Rock ........................................................................... 6
3.8 Mudflow and Debris Fan Areas ....................................................................................... 7
3.9 Development Over Faults and Risk of Seismic Activity ................................................... 7
3.10 Flood Prone Areas ........................................................................................................... 8
3.11 Collapsible Soils .............................................................................................................. 8
3.12 Mining Activity .................................................................................................................. 8
3.13 Radioactivity .................................................................................................................... 8
4.0 CONCLUSIONS AND RECOMMENDATIONS .................................................................. 10
5.0 REFERENCES ................................................................................................................... 11
FIGURES
List of Figures
Speakman A UIC Surface Ownership Map
Geology Map
NRCS Soils Map
Surface Water Map
A Floodplain Map
Geologic Hazard Report 1 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
1.0 EXECUTIVE SUMMARY
Olsson Associates (Olsson) was contracted by Ursa Operating Company to assess natural and
geologic hazards potentially present in the area of the proposed Speakman Pad A Class II
Underground Injection Control (UIC) well located in the NE ¼, SW ¼ Section 24, Township 7
South, Range 96 West, of the 6th Principal Meridian, Garfield County, Colorado. The site is at
an elevation of about 5,160 feet above mean sea level (amsl) as shown on the attached
Speakman A UIC Surface Owner Vicinity Map.
The purpose of this report is to identify geologic conditions that may pose hazards to a land
development project in order that appropriate mitigation or avoidance techniques may be
implemented as described in the Garfield County LUDC. According to the Garfield County
LUDC, Section 7-207, the types of natural and geologic hazards identified pertain to the
following:
A. Utilities;
B. Development in Avalanche Hazard Areas;
C. Development in Landslide Hazard Areas;
D. Development in Rock-fall Hazard Areas;
E. Development in Alluvial Fan Hazard Areas;
F. Slope Development;
G. Development on Corrosive or Expansive Soils and Rock;
H. Development in Mudflow Areas; and
I. Development Over Faults.
This report presents Olsson findings following an evaluation of these and other geologic
hazards potentially affecting the site and proposed development. The Ursa Operating Company
(Site) was found to be suitable for the proposed development with consideration of the following
identified geologic hazards.
Slope is a limitation associated with the Potts and Potts Ildefonso complex soils.
Community development and recreation are limited by low strength, shrink-swell
potential in addition to slope. It is expected that these limitations can be mitigated
through proper engineering, design, and construction practices.
According to the Preliminary Geologic Map of the Grand Valley Quadrangle, Garfield
County, the proposed Site is located on Quaternary age (Holocene) “pre-historic” earth
flow and soil creep, and landslide deposits. Therefore, the Site is in a potential landslide
area. However, the well is proposed to be drilled on an existing well pad that has
several producing natural gas wells installed.
The Speakman Pad A UIC well can be constructed to compensate for these limitations and
potential hazards. This report should be read in its entirety, including but not limited to the
conclusions and recommendations in section 4.0.
Geologic Hazard Report 2 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
2.0 GENERAL SITE LOCATION AND BACKGROUND
Ursa Operating Company LLC (Ursa) contracted Olsson Associates (Olsson) to conduct a
natural and geologic hazards assessment as part of the proposed development of the
Speakman Pad A UIC Well. The proposed facility will be used to store and dispose of produced
water and other approved E&P water wastes. The following sections provide information about
the proposed development and the site geologic setting. The site surface and bedrock geology
is shown on the Geology Map.
2.1 Project and Site Description
The proposed Speakman Pad A UIC well pad is located to the southwest of the town of
Parachute, Colorado off of County Road 300. The site is located in the NE ¼ SW ¼ Section 24,
T7S, R96W, 6th P.M. and is located in parcel # 240924400124. The surface land is owned by
James and Monique Speakman. The site is located near the intersection of Stone Quarry Road
(County Road 300) and Daybreak Drive, southwest of the community of Battlement Mesa.
2.2 Structural Geology
The Speakman Pad A UIC well pad Site is located in the southeastern part of the Piceance
Basin. The Piceance Basin is an irregularly-shaped elongated basin formed by tectonic forces
associated with the Laramide orogeny. These forces down warped the earth’s crust and formed
the Piceance Basin as a result of the uplift of the surrounding Colorado Rocky Mountains and
the Colorado Plateau.
The Piceance Basin is the major structural geologic feature in the region. It is bound to the east
by the Grand Hogback monocline, the White River Uplift to the northeast, the Gunnison Uplift to
the south, the Uncompahgre Uplift to the south and southwest, the Douglas Creek Arch to the
west-northwest, and the axial basin uplift to the north (Grout and Verbeek, 1992).
Sedimentary rocks in the southwestern Piceance Basin gently dip to the north - northeast
except where this regional dip is interrupted by low-amplitude folds. Numerous small sub-
parallel northwest trending folds have been identified in the Green River Formation within the
basin. The Divide Creek and Wolf Creek anticlines are two gentle, north-northwest trending,
gas producing intrabasin folds located near the eastern margin of the Piceance Basin.
There are no mapped faults shown in the area of the site on the Geologic and Structure Map of
the Grand Junction Quadrangle, Garfield County, Colorado (Cashion, 1973) or on the
Preliminary Geologic Map of the Grand Valley Quadrangle, Garfield County, Colorado (Donnell,
Yeend, Smith, 1986). A fault is a fracture in rock along which movement has occurred.
Mountains are bound by faults and are a visible indication of a structural weakness in the earth’s
crust. The Colorado Rocky Mountains are bound by faults; however, these faults are not always
visible at the ground surface either because the fault trace is ‘blind’ meaning that the fault does
not have surface expression since it does not cut across overlying sedimentary bedrock units, or
that it has been buried and concealed by unconsolidated sediments deposited over the area
where the faults are present. There are no known major faults that have been mapped in the
area of the Site.
Geologic Hazard Report 3 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
2.3 Site Geology
According the Preliminary Geologic Map of the Grand Valley Quadrangle (Donnell, Yeend,
Smith, 1986), the bedrock mapped in the project area consists of the Eocene and Paleocene-
age Shire Member of the Wasatch Formation which consists of purple, lavender, gray, and
brown claystone, with minor beds of fine- to medium-grained sandstone. The maximum
exposed thickness of the Wasatch is approximately 1,200 feet.
The bedrock in the area of the Site is covered with unconsolidated sediments of Quaternary age
consisting of earthflow and soil creep deposits, and landslide deposits. These deposits are
poorly sorted and are comprised of boulder, cobble, and pebble gravel in a matrix of greenish-
gray sandy silt. Some basalt boulders derived from older glacial till, landslide, and colluvial
deposits are contained within these earthflow and soil creep deposits. Other clasts within the
unit are comprised of angular fragments of sandstone, siltstone, and claystone derived from the
Wasatch and Green River Formations. The maximum thickness of these deposits is
approximately 30 feet. Other units in the area consist of modern alluvium and colluvium
deposited along the Colorado River flood plain and its tributary drainages.
2.4 Soil
The Natural Resources Conservation Service (NRCS)Soils Map shows the area soil types.
Soils, consisting of the following units, are within the study area around Speakman Pad A UIC
well:
Potts Loam, 6 to 12 % slopes, Map Symbol 56: The Potts loam is a deep, well drained,
moderately sloping to rolling soil found on mesas, benches, and the sides of valleys at
elevations between 5,000 feet and 7,000 feet. The soil formed in alluvium derived from
sandstone, shale, or basalt. Permeability is moderate, and the available water capacity
is high. Community and recreational development are limited by low strength, shrink-
swell potential, and slope. Dwellings and roads can be designed to overcome these
limitations.
Potts Ildefonso Complex, 12-25% slopes, Map Symbol 58: The Potts Ildefonso complex
are described as strongly sloping to hilly soils that are found on mesas, alluvial fans, and
the sides of valleys at elevations ranging from 5,000 feet to 6,500 feet. The Potts soils
are as described above, while the Ildefonso soil formed in strongly calcareous, basaltic
alluvium, with small amounts of eolian material. The unit is deep, and well drained. The
Ildefonso soil typically has a stony surface layer of brown loam, while the underlying
material is white, calcareous, and very stony. Permeability is moderately rapid, surface
runoff is medium, and the erosion hazard is moderate. Community and recreational
development is limited by low strength, shrink-swell potential and very steep slopes.
The Potts soil makes up approximately 60% of the unit, and the Ildefonso soil makes
about 30% of the unit, with the Morval and Lazear soils making up the remaining 10%.
The Morval soils are at higher elevations and the Lazear soils are shallow and are found
on ridge crests and steep mountain sides.
Geologic Hazard Report 4 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
2.5 Hydrologic Setting
The Site is located on a terrace above the Colorado River flood plain. The Colorado River is
located approximately 2,000 feet to the north-northwest. The Dry Creek drainage is located
approximately 1,645 feet to the west. There is an unnamed drainage that runs along the base
of the High Mesa located approximately 700 feet to the northeast of the Site. These surface
water features are shown on the Surface Water Map.
2.6 Aquifers
The shallow aquifer in the area of the proposed Site consists of earthflow, soil creep, landslide,
and fan gravels of the Grand Mesa formation as mapped by Yeend and Donnell (1968). The
estimated groundwater flow direction is likely to be sub-parallel with the Colorado River, flowing
north-northwest toward the Colorado River through the center and northern part of the proposed
site. These deposits are shown on the Geology Map.
Shallow ground water is also present within the alluvial gravels of the Colorado River, and its
tributary drainages. Based on a review of permitted water wells in the vicinity of the site, static
water levels range between 43 feet and 85 feet below ground surface (bgs).
Geologic Hazard Report 5 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
3.0 NATURAL AND GEOLOGIC HAZARD ASSESSMENT
The following sections present the assessment of geologic hazards in the vicinity of the
proposed Water Impoundment. The Surface Owner Vicinity Map shows the location of the
Speakman Pad A UIC Well Site in relation to the affected parcel and local roads.
3.1 Utilities
Above-ground utility facilities located in Hazard Areas are to be protected by barriers or
diversion techniques approved by a qualified professional engineer. The determination to locate
utility facilities above ground shall be based upon the recommendation and requirements of the
utility service provider and approved by the County. Above-ground utilities, such as
transformers, are not expected to be affected by geologic or other natural hazards.
Trenches for water pipelines, natural gas pipelines, and electrical lines are expected to be
associated with the proposed development. The slopes and depth to shallow bedrock may
pose technical challenges to the installation of these utilities; however, it is expected that these
limitations can be overcome with proper design and installation.
There are existing natural gas wells in the area, an overhead power line to the north of the Site,
Stone Quarry Road and houses to the north of the Site, and Daybreak Drive to the west of the
Site.
3.2 Avalanche Hazard Area
Winters are cold in the mountainous areas of Garfield County, and valleys are colder than the
lower parts of adjacent mountains due to cold air drainage. Average seasonal snowfall in
Garfield County is 50 inches. The greatest snow depth at any one time during the period of
record from 1951 to 1974 was 29 inches recorded at Rifle, Colorado approximately 25 miles to
the east-northeast of the proposed site.
Avalanches are not expected to affect the proposed injection well Site since it is located at an
elevation of approximately 5,160 feet amsl. Areas in eastern Garfield County are at higher
elevations, receive more snow pack, and are therefore more prone to avalanches in certain
years.
Avalanches are the most dangerous geologic hazard in Colorado resulting in injuries, loss of
life, and about $100,000 in direct property damage, and indirect economic losses in the millions
of dollars annually. However, the avalanche prone areas include the Park Range and Flat Tops
in northeastern Garfield County, Colorado, to the north of Glenwood Springs. Glenwood
Springs, near the east edge of the area, averages about one degree cooler than Rifle and
receives about five inches more precipitation per year (Harman and Murray, 1985).
3.3 Landslide Areas or Potential Landslide Hazard Areas
The Site is located on earthflow, soil creep, and historic landslide deposits, and is therefore
within a landslide area or potential landslide hazard area. Landslides in western Colorado are
typically associated with areas of significant slopes covered with unconsolidated sediments.
Geologic Hazard Report 6 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
Landslides are natural and ongoing events in these areas. Landslides can be triggered by
human activities disrupting the land and periods of precipitation which increase the chances of
landslide occurrence.
The Site is on an existing well pad, with producing natural gas wells. There is an overhead
power line to the north of the Site and Stone Quarry Road was constructed along the base of
the slope of these Holocene landslides. There are houses to the north and northeast of the Site.
3.4 Rockfall Areas
The Site is not located within an area that has been mapped as having rockfall or potential for
rockfall. Potential rockfall areas may be present along the steep drainages incised by Dry
Creek to the southwest or at higher elevations to the south on Battlement Mesa.
3.5 Alluvial Fan Hazard Areas
The Site is not located within an alluvial fan hazard area. According to the Preliminary Geologic
Map of the Grand Valley Quadrangle (Donnell, Yeend, Smith, 1986), there are alluvial terrace
and fan deposits to the west of the Site. These deposits are about 100 feet to 200 feet above
the Colorado River flood plain, and are approximately 160 feet thick.
3.6 Unstable or Potentially Unstable Slopes
According to the Garfield County Slope Hazard Study Areas 1, 2, & 3 map, parts of the area
north of the Colorado River and the town of Parachute, Colorado have been mapped as being in
an area of major slope hazard. The map does not include the area south of the Colorado River
in the vicinity of the Site.
The slope hazard map recommends that site specific investigations should be conducted to
assess active landslide areas. Geologic studies may include intensive drilling and sophisticated
strength testing, stability analyses, and monitoring of soil, rock, and groundwater conditions.
Mitigation may be possible, but likely will be expensive, may require special siting, and will
involve some risk. Avoidance may be recommended for projects of lower economic value
(Garfield County, Slope Hazard Study 2002).
The Potts and the Potts Ildefonso complex soils were formed on 6% to 12% slopes.
Engineering, design, and construction practices of the proposed development are expected to
mitigate the limitation of slopes at the Site since the site is an existing well pad, graded and
constructed for this purpose, and is in an area with slopes that are not as steep as surrounding
areas.
3.7 Corrosive or Expansive Soils and Rock
According to the Soil Survey of the Rifle Area, the Potts and the Potts Ildefonso soils are slightly
acidic to slightly alkaline, but generally have a neutral pH ranging from 6.6 to 7.8 standard pH
units. Sedimentary rock containing high salt content, such as chloride or sulfate, and soils
derived from these rock types, may be corrosive to concrete or metal, causing damage to
structures built upon them. These conditions are not expected to be a hazard present in the
vicinity of the Site.
Geologic Hazard Report 7 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
Some Tertiary and Cretaceous age sedimentary rocks with high clay content are capable of
accepting water into their chemical structure and expand many times their volume when dry.
These sedimentary rocks, and soils formed from these rock types, may expand or contract as
they become wet and then dry out resulting in damage to structures built upon them.
The Potts soils have shrink-swell potential which pose a limitation for some community and
recreational development, but are not expected to adversely impact the proposed UIC well
construction.
3.8 Mudflow and Debris Fan Areas
The Site is located in an area of earth flow and soil creep deposits located on terraces above
the Colorado River drainage. These deposits are Holocene in age and future slides are a
potential hazard. The proposed Speakman A Class II UIC well is located on an existing well
pad, and there is other development in the area including a power line and Stone Quarry Road
to the north, and Daybreak Drive to the west. There are several homes in the area.
3.9 Development Over Faults and Risk of Seismic Activity
There are no major faults shown in the Grand Valley area on the Geologic and Structure Map of
the Grand Junction Quadrangle, Colorado and Utah (Cashion, 1973). There are no mapped
faults shown on the Preliminary Geologic Map of the Grand Valley Quadrangle, Garfield County,
Colorado (Donnell, Yeend, and Smith, 1986) in the immediate vicinity of the Site.
The Piceance Basin and other Tertiary age basins of the Colorado Plateau are defined by
monoclines, at least along one margin. The Grand Hogback, to the east near the town of Rifle,
is such a monocline which is thought to have formed by reactivation of pre-existing, steeply
dipping fault zones in the Precambrian basement rock. Recent seismic data suggests that
some of the monoclines, especially in the Rocky Mountain foreland near the boundary with the
Colorado Plateau, overlie a west-, southwest-, or south-directed thrust fault system. These
blind thrust faults transect older Mesozoic and Paleozoic sedimentary rocks that resulted from
two major deformational events associated with the uplift of the ancestral Rocky Mountains.
The Grand Hogback monocline formed above the tip of a blind, Precambrian basement rock
thrust fault wedge which moved southwest and west-southwest into the Piceance basin (Grout
and Verbeek, 1992).
Colorado is considered a region of minor earthquake activity; however, there is uncertainty due
to the relatively short historic record. According to the USGS Colorado Earthquake History
online, newspaper accounts were the primary source of earthquake data in Colorado prior to
1962. Few earthquakes have been reported in this part of Colorado. A very minor earthquake
occurred in the northwestern part of Colorado on November 22, 1982 at 3:09 a.m. MST. The
magnitude 2.9 earthquake was located about 18 miles northeast of the town of Rifle and was
felt at a fish hatchery in the area.
The largest quake in the area occurred on April 22, 1984 and had a magnitude of 3.1 on the
Richter scale. The quake was felt in Carbondale and in Glenwood Springs. Of the hundreds of
quakes that occurred in the Carbondale area during that time period, 12 were reported as felt.
Geologic Hazard Report 8 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
3.10 Flood Prone Areas
The facility is not within a FEMA flood hazard zone and there are no surface waters located in
the vicinity of the project. The Colorado River flood plain is located to the north and northwest
of the Site, but is at lower elevation and is not expected to be a hazard associated with the
proposed development. The terraces lie at elevations of 100 feet to 200 feet above the
elevation of the Colorado River flood plain. The flood plain along the Colorado River is shown in
relation to the Speakman A pad on the attached Flood Plain Location Map.
3.11 Collapsible Soils
Collapsible soils are another type of subsidence that occurs in parts of western Colorado where
unconsolidated sediments are present. This ground settlement can damage man-made
structures such as foundations, pavements, concrete slabs, utilities, and irrigation works.
Collapsible soils have not been mapped in the area and are not expected to be encountered in
the vicinity of the Site.
3.12 Mining Activity
A review of the Grand Valley 7.5-minute quadrangle did not show any significant mining
activities in close proximity to the proposed UIC well Site. Oil shale mining was conducted north
of the town of Parachute, and there are sand and gravel operations along the Colorado River.
There are no mining activities shown in the immediate area of the Site. Natural gas wells are
shown in the surrounding areas of the proposed UIC well Site.
3.13 Radioactivity
Naturally occurring radioactive materials are not expected to be an issue at the Site. Colorado
oil and gas operations are not known to have a significant problem with naturally occurring
radioactive materials (NORM) or technologically enhanced naturally occurring radioactive
materials (TENORM); however, there have been some instances where pipe scale has
contained radium and associated radon gas. A NORM survey including site specific testing
could be performed to further assess the radon potential at the Site to serve as a baseline
assessment if used pipe or pipe scale is to be disposed offsite in the future.
Olsson reviewed the Colorado Bulletin 40, Radioactive Mineral Occurrences of Colorado which
states that nearly all of Garfield County’s uranium production came before1954, and most of
that came from the Rifle and Garfield mines, located along the same ore body near the town of
Rifle. These occurrences were all hosted in the Jurassic Morrison and Entrada Formations, and
the Triassic-Jurassic Navajo Sandstone, or the Triassic Chinle Formation which are known to
contain uranium and vanadium deposits in the county and in the Colorado Plateau in general
(Nelson-Moore, Collins, and Hornbaker, 1978). These formations lie at great depth in the
vicinity of the Site and are stratigraphically below the depth of the Wasatch Formation.
The Colorado Department of Public Health and Environment (CDPHE) has posted a statewide
radon potential map on their website based on data collected by the EPA and the U.S.
Geological Survey. Garfield County and most of Colorado has been mapped as being within
Zone 1 – High Radon Potential, or having a high probability that indoor radon concentrations will
exceed the EPA action level of 4 picocuries per liter (pCi/L).
Geologic Hazard Report 9 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
Radon is not expected to be a significant problem at the proposed site since the development
will not include any permanent structures, personnel will not be onsite for extended periods, and
the site will not be developed with structures containing basements or substructures in which
radon can accumulate.
Geologic Hazard Report 10 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
4.0 Conclusions and Recommendations
The following conclusions and recommendations were made following a review of the available
site data for natural and geologic hazards in the vicinity of Speakman Pad A UIC Well Site
located in Garfield County, Colorado.
Geological hazards are not expected to be associated with the installation of buried
utilities. Slopes may be a limitation to this construction, but this limitation should be able
to be overcome with proper engineering, design, and construction.
Avalanche conditions are not expected to be present in area of the Site.
The site is located on pre-historic earthflow and soil creep deposits having the potential
to be a geologic hazard affecting the Site. There are existing wells on the location and
there is other development in the area.
Rockfall areas are not present in the area of the Site. Rockfall areas are present in parts
of the steep canyons and narrow drainages incised by area streams, but are not
expected to be a hazard in the vicinity of the Site.
The Site is not in an alluvial fan hazard area. Alluvial fans are present to the northwest
between the site and the Colorado River drainage.
Slope is a limitation associated with the Potts and the Potts Ildefonso complex soils and
certain types of development. The Speakman Pad A UIC well construction is not
expected to be adversely affected by the slopes in the area.
Corrosive or expansive soils and rock are not expected to be present in the vicinity of the
proposed water impoundment Site. Rocky soils may exist in the vicinity of the site which
may impact the proposed development.
Collapsible soils are not present in the vicinity of the proposed UIC Well Site.
No significant faulting is known in the UIC Well Site.
No flood prone areas are mapped in the vicinity of the site. Flash flooding is an issue for
lower elevations along Dry Creek and areas along the Colorado River located to the
north and west are prone to flood risks.
There are no mining activities shown in the vicinity of the site. Natural gas well drilling
has been conducted in the area since the 1960s.
There are no significant radioactive mineral deposits known in the immediate area of the
site. The presence of NORM may be an issue with exploration and production and could
be an issue with used pipe scale or used equipment. Radioactive materials are not
expected to pose a significant hazard at the Site.
Geologic Hazard Report 11 Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO February 2014
5.0 References
Cashion, W.B., 1973, Geologic and Structure Map of the Grand Junction Qudrangle,
Colorado and Utah, USGS, Map I-736, scale 1:250,000
Donnell, J.R., Yeend W.E., Smith M.C., 1986, Preliminary Geologic Map of the Grand
Valley Quadrangle, Garfield County, Colorado, scale 1:24,000
Grout, M. A. and Verbeek, E.R., 1992, U.S.G.S. Bulletin 1787-Z, Fracture History of the
Divide Creek and Wolf Creek Anticlines and Its Relation to Laramide Basin-Margin
Tectonism, Southern Piceance Basin, Northwestern Colorado, 32 p.
Fischer, R.P., 1960, Vanadium-Uranium Deposits of the Rifle Creek Area, Garfield
County, Colorado, U.S.G.S. Bulletin 1101, 52 p.
Hail, W.J., Jr., 1992, U.S.G.S. Bulletin 1787-R, Geology of the Central Roan Plateau
Area, Northwestern, Colorado, 26 p.,
Harman, J.B. and Murray, D. J., 1985, Soil Survey of Rifle Area, Colorado, Parts of
Garfield and Mesa Counties, Colorado: U.S. Department of Agriculture, Soil
Conservation Service, in cooperation with the Colorado Agricultural Experiment Station,
149 p. two plates, and 20 map sheets.
Nelson-Moore, J.L., Bishop Collins, D., Hornbaker, A.L., 2005, Colorado Geologic
Survey, Bulletin 40, Radioactive Mineral Occurrences of Colorado, pp 154-158 (CD)
Robson, S.G. and Banta, E.R., 1995, U.S.G.S. Hydrologic Investigations Atlas 730-C,
Groundwater Atlas of the United States, Segment 2, Arizona, Colorado, New Mexico,
Utah, 32 p.
Topper, R., Spray, K. L., Bellis, W.H., Hamilton, J.L., Barkman, P.E., Ground Water Atlas
of Colorado, Colorado Geologic Survey, 2003, Special Publication 53, 210 p.
Online References
Colorado Oil and Gas Conservation Commission http://cogcc.state.co.us/
Natural Resources Conservation Service - Soil Survey http://www.nrcs.usda.gov/
Garfield County
Slope Hazards: http://garfield‐county.com/geographic‐information‐
systems/documents/6439291200422slopehaz.pdf
Soil Hazards: http://garfield‐county.com/geographic‐information‐
systems/documents/64335291200423soilhaz.pdf
Surficial Geology of Garfield County: http://garfield‐county.com/geographic‐
information‐systems/documents/geologic‐hazards/24surfgeo.pdf
Colorado Geological Survey website: http://geosurvey.state.co.us/hazards
Colorado Geological Survey website: http://geosurvey.state.us/land/Pages/Professional
Geologist
Colorado Oil and Gas Conservation Commission website:
http://dnrwebcomapg.state.co.us/mapguide2010/
Geologic Hazard Report Olsson Associates
Ursa Operating Company Speakman A UIC Golden, Colorado
Garfield County, CO January 2014
FIGURES