HomeMy WebLinkAbout4.9.1 Oxy CC 604 12 13 Annex GeoHaz Rpt FNL Binder 012215NATURAL AND GEOLOGIC HAZARDS
ASSESSMENT REPORT
OXY 604-12-13 ANNEX
SW 1/4 NW 1/4 SECTION 4, T6S, R97W, 6TH P.M.
GARFIELD COUNTY, COLORADO
PREPARED FOR
OXY USA WTP LP
760 HORIZON DRIVE, SUITE 101
GRAND JUNCTION, COLORADO 81506
PREPARED BY
OLSSON ASSOCIATES
4690 TABLE MOUNTAIN DRIVE, SUITE 200
GOLDEN, COLORADO 80403
JANUARY 2015
PROJECT No. 014-2740
O\OLSSON®
ASSOCIATES
TABLE OF CONTENTS
TABLE OF CONTENTS i
FIGURES i
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 Bedrock Geology 3
2.4 Site Surficial Geology and 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 5
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 7
3.10 Flood Prone Areas 7
3.11 Collapsible Soils 8
3.12 Mining Activity 8
3.13 Radioactivity 8
4.0 Conclusions and Recommendations 10
5.0 Natural and Geologic Hazard Report Background 11
6.0 Professional Geologist Certification 13
7.0 References 14
FIGURES
List of Figures
Location Map
Geology Map
Soils Map
Surface Water Map
Geologic Hazard Report
OXY 604-12-13 Annex
Garfield County, CO
i
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
1.0 EXECUTIVE SUMMARY
Olsson Associates (Olsson) was contracted by OXY USA WTP LP (Oxy) to assess natural and
geologic hazards potentially present in the area of the proposed 604-12-13 Annex in Garfield
County, Colorado. The site will be used to store oilfield equipment including pipe, fittings,
valves, and tanks. No structures are planned to be constructed onsite. The site lies at an
elevation greater than 8,630 feet above mean sea level (amsl). The Location Map shows the
general location of the 604-12-13 Annex.
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
1. 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 site was found to be
suitable for the proposed development, but is in an area of steep slopes northeast of Cascade
Canyon. A slope hazard analysis was prepared for the 604-12-13 annex site by D.R. Griffin &
Associates, in Rock Springs, Wyoming. The area to the west of the site shows slopes greater
than 30%. D.R. Griffin also prepared a Drainage Report for the Cascade Creek 604-12-13 site.
The site is located on a topographic high and there is a potential for unstable or potentially
unstable slopes and associated rock fall and slides to impact the development. Steep slopes
are found in areas to the northeast and east of the 604-12-13 Annex Site. The mitigation should
be designed by a qualified and licensed professional engineer in accordance with Section 4-203
and Section 7-108 of the LUDC. A qualified licensed professional engineer should make the
final determination on how to best mitigate these risks, but the site should be able to be
developed for its intended use.
There is an existing storage pad located to the southwest of the existing Cascade Canyon 604-
12-13 well pad. Access roads to the well pad are located on the northeast side of the existing
equipment storage pad. Steep slopes are located on all sides of these facilities. This report
should be read in its entirety, including but not limited to the conclusions and recommendations
in Section 4.0.
Geologic Hazard Report
OXY 604-12-13 Annex
Garfield County, CO
1
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
2.0 GENERAL SITE LOCATION AND BACKGROUND
Oxy contracted Olsson Associates (Olsson) to conduct a natural and geologic hazards
assessment as part of the proposed development of the 604-12-13 Annex Site. The following
sections provide information about the proposed development and the site geologic setting.
2.1 Project and Site Description
The Oxy 604-12-13 Annex Site will be used as an equipment and materials storage facility. The
Site is located near Cascade Canyon north of the town of DeBeque in western Garfield County,
Colorado. The site is located in the SW 1/4 NW 1/4 Section 4 and Lot 13 (SE 1/4 NE 1/4 ) Section 5,
Township 6 South, Range 97 West, of the 6th Principal Meridian.
2.2 Structural Geology
The proposed Site is located in the southeastern part of the Piceance Basin; an irregularly
shaped elongated basin formed by tectonic forces associated with the Laramide orogeny.
Tectonic forces down warped the earth's crust to form the Piceance Basin as a result of the
uplift of the surrounding Colorado Rocky Mountains and the Colorado Plateau. The site is
located on the Roan Plateau in the proximity of Cascade Canyon. The site is located on the
Circle Dot Gulch 7.5 -minute topographic map.
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 southwest, the Douglas Creek Arch to the west-
northwest, and the axial basin uplift to the north (Grout and Verbeek, 1992). The central Roan
Plateau area covers an area of approximately 230 square miles in Garfield and Rio Blanco
Counties in the south-central part of the Piceance Basin in northwestern Colorado.
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 project site is located approximately a mile south of the axis of the Crystal Creek
anticline. The 604-12-13 Annex Site is also located near the axis of the Clear Creek syncline
which passes through the southwest quarter of Section 5. The Crystal Creek anticline and the
Clear Creek syncline are a northwest trending fold system that start near the Colorado River
and extend for a distance of approximately 30 miles. The Crystal Creek anticline forms the
southeastern element of an anticlinal fold that trends across the southwestern part of the
Piceance Basin. The Clear Creek syncline is a parallel fold located to the southwest (Hail,
1992).
A fault is a fracture in rock along which movement has occurred. No significant faulting is
known in the project area, but some jointing may occur in proximity to the folds. Three narrow
down -dropped block valleys, known as grabens and bound by normal faults, are present along a
northwest trending fracture zone in the northern part of the area. The maximum stratigraphic
displacement on these faults does not exceed 120 feet and most displacements are
Geologic Hazard Report
OXY 604-12-13 Annex
Garfield County, CO
2
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
considerably less. Small northwest striking faults between the graben in the central part of
Township 4 South, Range 97 West and the graben in southwestern part of Township 4 South,
Range 96 West suggest that the grabens lie along a single fracture zone that extends for a total
distance of approximately nine miles (Hail, 1992).
2.3 Site Bedrock Geology
As shown on the attached Geology Map, the bedrock underlying the proposed Site is
composed of the Unit D of the Tertiary age Uinta Formation. This unit consists of brown
weathering siltstone and fine-grained to medium -grained sandstone; light -brown to light -gray
weathering marly siltstone and silty marlstone, subordinate oil shale and minor limestone and
coarse-grained to conglomeratic sandstone. The Unit D is nonresistant and weathers to
rounded slopes. The maximum thickness is approximately 540 feet.
The Unita Formation is underlain by the Tertiary age Green River Formation. These units are
composed of claystone, siltstone, shale, and marlstone. The Roan Cliffs expose hundreds of
feet of the Green River Formation. The Green River Formation has been subdivided into four
members which include the basal Douglas Creek member, Garden Gulch member, the Anvil
Points member, and the Parachute Creek Member. Underlying the Green River Formation are
the early Eocene and Paleocene Wasatch and Fort Union Formations as well as the Cretaceous
Mesaverde Group (Robson and Banta, 1995).
The lower part of the Green River Formation is comprised of the Douglas Creek and Garden
Gulch members and is considered a confining unit that separates the overlying Lower Piceance
Basin aquifer in the Anvil Points Member from the underlying Fort Union and Mesaverde
aquifer. A thin layer of modern alluvium associated with the Conn Creek drainage covers the
bedrock near the site.
2.4 Site Surficial Geology and Soil
The proposed 604-12-13 Annex Site is located on Pleistocene and Holocene deposits that
include alluvium, alluvial fans, talus, and slope wash. These surficial deposits consisting of silt,
sand, and clay were derived primarily from the weathering of the Uinta Formation. Erosional
processes dominate in this setting, as the weathered soils are drawn toward the surrounding
canyons by precipitation, snowmelt, and wind.
The Soils Map shows the soil types beneath the site and surrounding properties. The proposed
Site is underlain by soils mapped by the U.S. Natural Resources Conservation Service as the
Parachute-Irigul complex , which is a shallow to deep, well -drained soil found on mountains
ridges and on the crests and sides of hills occupying 5 percent to 30 percent slopes, at
elevations of 7,600 to 8,800 feet. It is formed in colluvium and residuum derived dominantly
from sandstone, siltstone, and hard shale. Typically the surface layer is grayish brown loam and
is about 10 inches thick. The subsoil is a brown very channery loam about 15 inches thick.
Fractured bedrock lies at depths of about 25 inches. Permeability is moderate, and the available
water capacity is very low. Runoff is medium or rapid, and the hazard of water erosion is
moderate to very severe.
Geologic Hazard Report
OXY 604-12-13 Annex
Garfield County, CO
3
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
2.5 Hydrologic Setting
Surface water features within two miles of the project site include Cascade Creek,
approximately 950 feet to the southwest. The confluence of Cascade Creek and Conn Creek is
located approximately two miles to the southwest. The proposed 604-12-13 Annex Site will be
located adjacent to existing facilities. There are intermittent drainages located to the north and
south of the Site.
The site is shown on the USGS 1:24,000 topographic map (Circle Dot Gulch Quadrangle).
Cascade Creek has perennial flow, although no flow records are available to determine the flow
conditions in these drainages. Evaluation of aerial imagery in Google Earth° taken in June
2014 shows water flow in Cascade Canyon down in the bottom of the canyon near the proposed
storage facility. The Surface Water and Hydrologic Map shows the site in proximity to
Cascade Canyon.
2.6 Aquifers
The 604-12-13 Annex Site is located on a ridge top above the rim of Cascade Canyon. The
Uinta — Animas aquifer in the Piceance Basin consisting of the Uinta Formation and the
Parachute Creek Member of the Green River Formation lie topographically and stratigraphically
beneath the Site. The bedrock in the area of the 604-12-13 Annex Site consists of the Unit D of
the Uinta Formation.
The depth to groundwater is variable. There are no permitted water wells shown in Section 4 or
Section 5 nor in the immediate vicinity of the Site. There are permitted water wells as monitoring
holes in Section 5 listed as belonging to Williams or WPX Energy located northwest of the site
at elevations of less than 8,400 feet amsl. Groundwater may be present at depths of 25 feet
below ground surface (bgs) based on area water well records from the Colorado Division of
Water Resources for nearby wells. The presence and quantity of shallow groundwater is
controlled by the thickness of alluvium along major stream drainages. The presence of
groundwater in bedrock is controlled by fractures and interconnection of fractures in bedrock, as
well as the presence of less permeable layers that are exposed in the drainages and along
canyon walls. Springs are shown on the Circle Dot Gulch topographic map in parts of Section 5
at approximately 8,160 feet to 8,200 feet amsl in the bottoms of the drainages that drain to the
Cascade Canyon.
Geologic Hazard Report
OXY 604-12-13 Annex
Garfield County, CO
4
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
3.0 NATURAL AND GEOLOGIC HAZARD ASSESSMENT
The following sections present the assessment of geologic hazards in the vicinity of the
proposed 604-12-13 Annex Site. This site was previously developed for use as an existing
storage facility and adjacent to an active well pad.
3.1 Utilities
Installation of buried utilities may be affected by the relatively shallow depth to sedimentary
bedrock and fractures within the bedrock substrate. The 604-12-13 Annex Site is to be used for
the storage of equipment, so buried utilities are not expected to be associated with the Site. A
pipeline right-of-way appears to be located to the north of the facility and crosses access roads
located on either side of the existing storage facility.
3.2 Avalanche Hazard Area
The site is not located in a known 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.
The 604-12-13 Annex Site is located at an elevation of approximately 8,200 feet, but is not
expected to be within an avalanche prone area. Therefore, avalanches are not expected to
pose a hazard to the proposed development.
3.3 Landslide Areas or Potential Landslide Hazard Areas
The site and access road are not located within an area that has been mapped with landslide
hazard areas. It is on a ridge near the rim of Cascade Canyon in an area surrounded by steep
slopes composed of the Uinta Formation and Green River Formation. It appears that there are
slide areas located within Cascade Canyon to the southwest of the 604-12-13 Annex Site based
on site photographs and aerial photography. Debris fans appear at the base of the slopes and
appear to have mature vegetation covering them. It is possible for future slides and rock fall to
occur in this area.
3.4 Rockfall Areas
The Site and access road are in an area with potential for rockfall. Rockfall areas are present to
the southwest in the steep precipices. The site is located between two drainages that flow
toward the Cascade Canyon. There are apparent rockfall areas along the steep sides of the
canyon that have occurred in the past, and therefore have the potential for future rockfalls.
The Site will be constructed with a buffer area around the perimeter to protect it in the event of
rock falls. According to Slope Hazard Analysis prepared by D.R. Griffin & Associates, of Rock
Springs, Wyoming, dated 11/06/2014, the 604-12-13 Annex is surrounded by slopes that are
greater than 30 percent. A qualified licensed professional engineer in accordance with Section
Geologic Hazard Report
Oxy 604-12-13 Annex Facility
Garfield County, CO
5
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
4-203 and 7-108 of the LUDC should make the final determination on how to best mitigate
rockfall risks.
3.5 Alluvial Fan Hazard Areas
The Site is not located in a mapped alluvial fan hazard area. Alluvial fans are present at the
mouths of the canyons where they discharge onto the Colorado River floodplain, but are not
present in the immediate vicinity of the 604-12-13 Annex Site.
3.6 Unstable or Potentially Unstable Slopes
Much of the area immediately north and west of the towns of DeBeque and Parachute is
considered to have major slope hazards. An area of major hazard, such as an active landslide
area, may require more investigation which includes geologic study, intensive drilling, and
sophisticated strength testing stability analyses, and monitoring of soil, rock, and groundwater
conditions during the engineering and design phase of the project. Mitigation may be possible,
but also may 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 Slope Hazard Analysis prepared by D.R. Griffin & Associates shows the areas surrounding
the site have greater than 30% slope. As stated in the previous sections, the 604-12-13 Annex
Site is not expected to have any above grade structures constructed on it and will be used for
the storage of equipment and materials. D.R. Griffin & Associates also prepared a Drainage
Report for the Cascade Creek 604-12-13 Site. The Site was previously graded and constructed
for use as a gas well pad. The Site has access roads located to the east and southeast. Slopes
to the north and west are potentially unstable. Engineering controls may be able to mitigate
some small rockfall, slides, or debris flows, so the Site should be suitable for its intended use.
3.7 Corrosive or Expansive Soils and Rock
The 604-12-13 Annex Site and access roads are not located in an area known to have
expansive soil or rock types, although building site development for local roads and streets is
very limited due to slope, depth to hard bedrock, and frost action. Shallow excavations are very
limited due to slope, depth to bedrock, and cutbank caving. Sedimentary rock containing high
salt content, such as bicarbonate, chloride or sulfate, and soils derived from these rock types,
may be corrosive to concrete or metal, causing damage to structures built upon them. The
potential for the Parachute-Irigul complex soils have pH ranges from 6.6 to 7.8 standard units
and are not known to have a high salinity or SAR. According to the Soil Survey of the Douglas -
Plateau Area, Colorado, the Parachute-Irigul complex soils have a moderate potential of
corrosion to uncoated steel, but a low potential of corrosion to concrete.
This is not expected to be an issue with the proposed development, since the project involves
construction of an equipment storage annex. This site was previously developed for use as a
storage facility and is adjacent to the Cascade Canyon 604-12-13 well pad.
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.
Geologic Hazard Report
Oxy 604-12-13 Annex Facility
Garfield County, CO
6
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
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. Expansive
conditions are not expected. This condition does not pose a hazard, since occupied structures
are not expected to be constructed onsite.
3.8 Mudflow and Debris Fan Areas
The 604-12-13 Annex Site is not located in an area mapped as having mudflows or debris fans.
However, it appears that there are drainages on the north side and south side of the ridge on
which the 604-12-13 Annex Site is located. The ridge on which the site is located appears to be
supporting vegetation based on a review of June 2014 aerial photographs. There are slide
areas and debris fans to the southwest of the Site along the Cascade Canyon.
3.9 Development Over Faults
No significant faulting is known in the project area, but some jointing may occur in proximity to
the folds mentioned in the structural geology section. Three narrow down -dropped block valleys,
known as grabens and bound by normal faults, are present along a northwest trending fracture
zone several miles north of the 604-12-13 Annex Site. The maximum stratigraphic displacement
on these faults does not exceed 120 feet, and most displacements are considerably less. Small
northwest striking faults between the graben in the central part of Township 4 South, Range 97
West and the graben in southwestern part of Township 4 South, Range 96 West suggest that
the grabens lie along a single fracture zone that extends for a total distance of approximately
nine miles (Hail, 1992).
According to the Geologic and Structure Map of the Grand Junction Quadrangle, 1:250,000
scale, there are no mapped faults in the immediate vicinity of the proposed site. The Preliminary
Geologic Map of the Circle Dot Gulch Quadrangle Map, 1:24,000 scale (Hail, 1982), does not
show any faults in proximity to 604-12-13 Annex Site.
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. The Roan Plateau is not
in an area of known seismic activity; and therefore, earthquakes are not expected to present a
significant hazard.
3.10 Flood Prone Areas
According to available information from the Federal Emergency Management Agency (FEMA)
National Flood Insurance Program, Flood Insurance Rate Map (FIRM), the site is not located
within the 100 -year floodplain or 500 -year floodplain. The Floodplain map prepared for the
vicinity of the town of DeBeque and along the Colorado River. It is not in close proximity to the
604-12-13 Annex Site.
Flash floods could pose a hazard for the small intermittent drainage located to the north and
south of the Site, but are not expected to pose a hazard to the Site itself.
Geologic Hazard Report
Oxy 604-12-13 Annex Facility
Garfield County, CO
7
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
3.11 Collapsible Soils
Collapsible soils are another type of subsidence that occurs in parts of Colorado where
unconsolidated sediments are present. This ground settlement can damage man-made
structures such as foundations, pavements, concrete slabs, utilities, and irrigation works.
Hydrocompactive soils are the most common type of collapsible soils. The presence or
introduction of water causes the soils to compact once they become wet. Hydrocompactive soils
form in semi -arid to arid climates in the western United States and large parts of Colorado in
specific depositional environments.
Collapsible soils have a low density and low moisture content where the grains are not packed
tightly together. These soils are strong in dry conditions, where the loose, skeletal fabric of
these soils is preserved because the grains are "tack -welded" due to the presence of binding
agents, such as clay or silt, soil suction pressures, or in some cases, other binding agents that
can break, soften, disperse, or dissolve when wet causing subsidence or settling. Silty clay and
clayey sandy soils onsite are potentially collapsible, although less likely onsite than subsidence
due to expansive soils.
Collapsible soil conditions may be present in alluvial fan, alluvial, colluvial, and eolian
depositional environments and are found in some areas along the Colorado River drainage
where fine-grained sediments have been deposited from higher elevations, but are not expected
to be present in the vicinity of the 604-12-13 Annex Site.
3.12 Mining Activity
A review of the Circle Dot Gulch 7.5 -minute topographic map shows several drill holes for
exploration of oil shale, but does not show underground mining of oil shale in the vicinity of the
604-12-13 Annex Site. No structures are planned for construction on the site; and therefore,
subsidence is not expected to be a geologic hazard affecting the 604-12-13 Annex Site.
3.13 Radioactivity
According to Colorado Geologic Survey Bulletin 40, Radioactive Mineral Occurrences of
Colorado, the only naturally occurring radioactive mineral occurrences in Garfield County
include uranium and vanadium deposits that occur near the town of Rifle (Nelson -Moore,
Collins, Hornbaker, 2005). These deposits are located in older Jurassic age sediments, are not
exposed in the vicinity of the site, and lie stratigraphically below the zones that are developed
for oil and gas production. Therefore, radioactivity is not expected to pose a hazard.
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).
Radon is not expected to be a hazard at the 604-12-13 Annex Site since the site will generally
not be occupied for extended periods and will not have buildings containing basements or
substructures in which radon can accumulate. Colorado oil and gas operations are not known
Geologic Hazard Report
Oxy 604-12-13 Annex Facility
Garfield County, CO
8
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
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.
Therefore, NORM/TENORM may be an issue with exploration and production and could
be present in scale found in used pipe, tanks, or vessels
Geologic Hazard Report
Oxy 604-12-13 Annex Facility
Garfield County, CO
9
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
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 the Oxy 604-12-13 Annex Site
located in Garfield County, Colorado.
• Geologic hazards were identified in the immediate vicinity of the Oxy 604-12-13 Annex
Site. These include steep slopes and potential for slides; however, the Site should be
suitable for development for its intended use if engineering controls are properly
designed and installed.
• Avalanche areas are present in the northeastern parts of Garfield County in parts of the
Park Range and Flat Tops mountain range. Avalanche conditions are not expected to
be a hazard in area of the 604-12-13 Annex Site.
• Landslide areas have not been mapped in the vicinity of the 604-12-13 Site. However,
there is evidence of slides or debris flows located to the southwest of the 604-12-13
Annex Site along the steep walls of the Cascade Canyon.
• Rockfall areas are present to the south-southwest along steep cliff faces of the Cascade
Canyon. Rockfall mitigation should be designed by a qualified licensed professional
engineer in accordance with Section 4-203 and 7-108 of the LUDC.
• Alluvial fan hazard areas are not present in the vicinity of the 604-12-13 Annex Site, but
are present further to the south in some areas along the Colorado River drainage.
• Slope development is not expected to be an issue on the 604-12-13 Annex Site, since
there are existing facilities located adjacent to the proposed Site. There are steep slopes
to the south and east of the Site. Engineering controls may be needed to control rock
fall and slides.
• Corrosive or expansive soils and rock are not present in the vicinity of the 604-12-13
Annex Site.
• Collapsible soils are not present in the vicinity of 604-12-13 Annex Site.
• No significant faulting is known in the 604-12-13 Annex Site.
• No flood prone areas are mapped in the vicinity of the 604-12-13 Annex Site. Flash
flooding is an issue for lower elevations along Cascade Canyon, major creek drainages
in the area, and areas along the Colorado River are prone to flood risks.
• There are no mining activities shown in the vicinity of the 604-12-13 Annex Site.
• There are no naturally occurring radioactive mineral deposits known in the site area.
NORM/TENORM may be an issue with exploration and production and could be present
in scale found in used pipe, tanks, or vessels.
• As stated in the previous sections, the 604-12-13 Annex Site is not expected to have any
occupied structures constructed on it, and will be used for the storage of oil and gas field
equipment and materials. Slopes to the north and west are steep and could become
potentially unstable if vegetation is disturbed. Access roads have been constructed on
either side of the existing storage. Engineering controls may be able to mitigate rockfall,
slides, or debris flows from steep slopes to enable the site to be developed. Appropriate
risk mitigation design should be determined by a qualified, licensed professional
engineer and performed as a part of this development.
Geologic Hazard Report
Oxy 604-12-13 Annex Facility
Garfield County, CO
10
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
5.0 Natural and Geologic Hazard Report Background
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 oris 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
Oxy 604-12-13 Annex Facility
Garfield County, CO
11
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
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.
"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
Oxy 604-12-13 Annex Facility
Garfield County, CO
12
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
6.0 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.
I am familiar with the geology of the area of the proposed Oxy located in the SW 1/4
NW 1/4 of Section 4 and Lot 13 SE %, NE'/, Section 5, Township 6 South, Range 97
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 have a Bachelor of Science degree from Colorado State University and have been
employed as a professional geologist since 1991.
I am a licensed Professional Geologist and Professional Geoscientist in other States,
including Texas, Utah, and Wyoming which do have licensing programs for
professional geologists.
Although I have not visited this Site, I have reviewed site work provided by Olsson
personnel, and I have performed other field work in the area of the Site.
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.
Prepared by Reviewed by
James W. Hix, PG - "Kevin J. Tayl
Senior Geologist Senior Geologis
Date: 01/19/2015 Date: 01/20/2015
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 al! applicable Federal, State, and local requirements in order to achieve the desired goals
or objectives.
Geologic Hazard Report
Oxy 604-12-13 Annex Facility
Garfield County, CO
13
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
7.0 References
• Alstatt, D.K., 2003, Soil Survey of Douglas -Plateau Area, Colorado Parts of Garfield and
Mesa Counties, U.S. Department of Agriculture, Soil Conservation Service, in
cooperation with the Colorado Agricultural Experiment Station 355 p., 1 pl, 46 map
sheets
• Czyzewski, G., Chapter 12 — The Piceance Creek Basin, Colorado Ground -Water
Association, Ground -Water Atlas, 1999 p 63-66.
• D.R. Griffin & Associates, Inc. Oxy Cascade Creek 604-12-13 Pad Slope Hazard
Analysis, November 6, 2014
• D.R. Griffin & Associates, Inc. Drainage Report Cascade Creek 604-12-13 Storage Area
Garfield County, Colorado, December 22, 2014, 29 p.
• 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.
• Hail, W.J., Jr., 1982, Preliminary Geologic Map of the Circle Dot Gulch Quadrangle,
Garfield County, Colorado, U.S.G.S., Map MF -1293; scale 1:24,000
• Hail, W.J., Jr., 1992, U.S.G.S. Bulletin 1787-R, Geology of the Central Roan Plateau
Area, Northwestern, Colorado, 26 p.,
• 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.
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://Barfield-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://dnrwebcomapq.state.co.us/mapouide2010/
Geologic Hazard Report
Oxy 604-12-13 Annex Facility
Garfield County, CO
14
Olsson Associates
Golden, Colorado
January 2015
Project #014-2740
FIGURES
PROJECT NO: 014-2740
DRAWN BY: JWH
DATE: 01/22/2015
OXY Cascade Creek 604-12-13 Annex
Site Location Map
Section 4 & Section 5, T6S, R97W, 6 P.M. Garfield County, Colorado
ON, OLSSON
ASSOCIATES
4690 Table MountainpDrive
Golden, COTorado 80403
TEL 303.237.2072
FAX 303.237.2659
FIGURE
L-1
LEGEND:
o Gas Well Location
Structural
Contour
Tu - Uinta
Formation
Tge — Green
River Formation
Evacuation
Creek Member
Tgp — Green
River Formation
Parachute
Member
—Fn— Mahogany
Bench
Tgg — Green
River Formation
Garden Gulch
Member
PROJECT NO: 014-2740
DRAWN BY: JWH
DATE: 01/22/2015
OXY Cascade Creek 604-12-13 Annex
Geologic Map
Section 4 & Section 5, T6S, R97W, 6 P.M. Garfield County, Colorado
ON, OLSSON
ASSOCIATES
4690 Table MountainpDrive
Golden, COTorado 80403
TEL 303.237.2072
FAX 303.237.2659
FIGURE
G-1
LEGEND:
Soil Unit
Boundary
hTa{ Unit Leclund
3
Douglas -Plateau Area, Colorado, Parts of
Garfield and Mesa Counties (C0582)
Map Map Unit Name Acres PerceH[
Unit in of AOI
Symbol AOI
52 WorthwaterAdel complex, 5 74.6 22.7%
to 50 percent slopes
55 Parachute-Irigul complex, 5 68.5 22.094,
to 30 percent slopes
56 Parachute-Trigul-Rhone 165,5 53.296
association, 25 to 50 percent
slopes
53 Silas loam, 1 t 12 percent 6.4 2.1%
sl apes
Totals for Area of Interest 311.0 100.0%
Map adapted from the USDA NRCS Websoil Survey
PROJECT NO: 014-2740
DRAWN BY: JWH
DATE: 01/22/2015
OXY Cascade Creek 604-12-13 Annex
Soils Map
Section 4 & Section 5, T6S, R97W, 6 P.M. Garfield County, Colorado
q=_OLSSON
ASSOCIATES
4690 Table Mountain Drive
Golden, &c do 80403
TEL 303.237.2072
FAX 303.237.2659
FIGURE
S-1
LEGEND:
• Gas Well
Location
Permitted
Water Well
Location
.9 Spring
,--) V! r
.�. I a e ,
7F/11/
T , ..5•lr�,r �Ci�irE201
/ ffff F
,�
'
^sem,r t l
r�.
y
I._1 i
; OX'fTF
Location f ? % r
Intermittent '" --- r 7
Stream
Location
PROJECT NO:
/,
`Cascade
Q,S. id,a eCrtof 691;65.5$B1" 1 r
'r , vA Ca de c{Z`ek�-7-45-bA r
/\.
/ f r rr Cascade,,Cr-- 16 �053'A
I f`
asc e- 7-0`
` EEK 71-67E9 ' r ,
E�E�t 97/5 -DEI /' r,` ' \ �_.e'
EI
23 / i ri J
1k e
/rr I IIr{1
i97;5:596, CAS6
g5'9760P r6:APre
el
tI
r \
7S V1/4 lk
11.,I , i. f S r
i r r
G \ti-: / 1
�. �\ ::::
iaE F .E
: REEK697-3-41'� CASC, DL•_CF E
IK
)fl7)/ ) 1
f 7l / iff
J f-� ,") I
014-2740
DRAWN BY: JWH
DATE: 01/22/2015
''5.2—case
/
, @ASC,
132'` ibASC�
7 0.. 76ba
ret ,,koterr-
• CASGAI E
f
OXY Cascade Creek 604-12-13 Annex
Surface Water and Hydrologic Map
Section 4 & Section 5, T6S, R97W, 6 P.M. Garfield County, Colorado
loidi
'
AS AC/2'C
C
K.6
ON- OLSSON
ASSOCIATES
4690 Table Mountain Drive
Golden, Conrado 80403
TEL 303.237.2072
FAX 303.237.2659
f !
FIGURE
SWH-1