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HomeMy WebLinkAbout4.9 Oxy CC 697 16 16 Annex GeoHaz Rpt FNL Binder 012215NATURAL AND GEOLOGIC HAZARDS ASSESSMENT REPORT OXY 697-16-16 ANNEX NE 1/4 NE 1/4 SECTION 16, 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 Floodplain Map Geologic Hazard Report OXY 697-16-16 Annex Garfield County, CO i Olsson Associates Golden, Colorado December 2014 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 697-16-16 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 8,200 feet above mean sea level (amsl). The Location Map shows the general location of the 697-16-16 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 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 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 697-16-16 annex site by DR Griffin & Associates, in Rock Springs, Wyoming. The area to the west of the site shows slopes greater than 30%. 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 697-16-16 Annex Site. Rockfall and slide 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. There is an existing storage pad located to the north of the existing Cascade Canyon 697-16-16 natural gas well pad. Access roads to the well pad are located on either 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 697-16-16 Annex Garfield County, CO 1 Olsson Associates Golden, Colorado December 2014 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 697-16-16 Annex Site. The following sections provide information about the proposed development and the site geologic setting. 2.1 Project and Site Description The Oxy 697-16-16 Annex Site will be used as an equipment 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 southeast quarter of the southwest quarter of Section 16, 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 downwarped 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 697-16-16 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 697-16-16 Annex Garfield County, CO 2 Olsson Associates Golden, Colorado December 2014 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 697-16-16 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-Rhone association, which is a shallow to deep, well -drained soil found on the tops of mountains and ridges and on the crests and sides of hills occupying 25 percent to 50 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 rapid, and the hazard of water erosion is very severe. Geologic Hazard Report OXY 697-16-16 Annex Garfield County, CO 3 Olsson Associates Golden, Colorado December 2014 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 697-16-16 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 Map shows the site in proximity to Cascade Canyon. 2.6 Aquifers The 697-16-16 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 697-16-16 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 16 nor in the immediate vicinity of the Site. Groundwater may be present at depths of 15 feet below ground surface (bgs) or may lie at depths of more than 695 feet 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 15 at approximately 8,200 feet amsl in the bottoms of the drainages that drain to the Cascade Canyon. Geologic Hazard Report OXY 697-16-16 Annex Garfield County, CO 4 Olsson Associates Golden, Colorado December 2014 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 697-16-16 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 697-16-16 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 697-16-16 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 697-16-16 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 of rockfall or 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 DR Griffin & Associates, of Rock Springs, Wyoming, dated 11/06/2014, the 697-16-16 Annex is surrounded by slopes that are greater than 30 percent. A qualified licensed professional engineer in accordance with Section Geologic Hazard Report Oxy 697-16-16 Annex Facility Garfield County, CO 5 Olsson Associates Golden, Colorado December 2014 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 697-16-16 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 697-16-16 Annex Site is not expected to have any above grade structures constructed on it and will be used for the storage of equipment. Slopes to the north and west are potentially unstable. The Site has access roads. Engineering controls may be able to mitigate some small rockfall, slides, or debris flows. 3.7 Corrosive or Expansive Soils and Rock The 697-16-16 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-Rhone soils have pH ranges from 6.6 to 7.8 standard units are not known to have a high salinity or SAR. According to the Soil Survey of the Douglas -Plateau Area, Colorado, the Parachute-Irigul-Rhone 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 697-16-16 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. 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 Geologic Hazard Report Oxy 697-16-16 Annex Facility Garfield County, CO 6 Olsson Associates Golden, Colorado December 2014 Project #014-2740 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 697-16-16 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 697-16-16 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 697-16-16 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 697-16-16 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 was prepared for the vicinity of the town of DeBeque and along the Colorado River. It is not in close proximity to the 697-16-16 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 697-16-16 Annex Facility Garfield County, CO 7 Olsson Associates Golden, Colorado December 2014 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 697-16-16 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 697-16-16 Annex Site. No structures are planned for construction on the site; and therefore, subsidence is not expected to be a geologic hazard affecting the 697-16-16 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 697-16-16 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 697-16-16 Annex Facility Garfield County, CO 8 Olsson Associates Golden, Colorado December 2014 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. Geologic Hazard Report Oxy 697-16-16 Annex Facility Garfield County, CO 9 Olsson Associates Golden, Colorado December 2014 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 697-16-16 Annex Site located in Garfield County, Colorado. • Geologic hazards were identified in the immediate vicinity of the Oxy 697-16-16 Annex Site. These include steep slopes and potential landslides, debris flow, and rock fall. • 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 697-16-16 Annex Site. • Landslide areas have not been mapped in the vicinity of the 697-16-16 Site. However, there is evidence of slides or debris flows located to the southwest of the 697-16-16 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 697-16-16 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 697-16-16 Annex Site, since there are existing facilities located adjacent to the proposed Site. There are steep slopes to the north and west 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 697-16-16 Annex Site. • Collapsible soils are not present in the vicinity of 697-16-16 Annex Site. • No significant faulting is known in the 697-16-16 Annex Site. • No flood prone areas are mapped in the vicinity of the 697-16-16 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 697-16-16 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. As stated in the previous sections, the 697-16-16 Annex Site is not expected to have any occupied structures constructed on it, and will be used for the storage of oil field equipment. 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 the north and west. Appropriate risk mitigation design should be determined by a qualified, licensed professional engineer should be performed as a part of this development. Geologic Hazard Report Oxy 697-16-16 Annex Facility Garfield County, CO 10 Olsson Associates Golden, Colorado December 2014 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 697-16-16 Annex Facility Garfield County, CO 11 Olsson Associates Golden, Colorado December 2014 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 697-16-16 Annex Facility Garfield County, CO 12 Olsson Associates Golden, Colorado December 2014 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 site located in the NE 1/4, NE 1/4, Section 16, 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 James W. Hix, PG Senior Geologist Date: 01/22/2015 Reviewed by Kevin J. Ta Senior Geo Date: 01/22/2 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 Oxy 697-16-16 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. • DR Griffin & Associates, Inc. Oxy Cascade Creek 697-16-16 Pad Slope Hazard Analysis, November 6, 2014 • 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://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 Oxy 697-16-16 Annex Facility Garfield County, CO 14 Olsson Associates Golden, Colorado December 2014 Project #014-2740 FIGURES P ®XV USA WTP LP OXY 760 Horizon Drive, Suite 101 '/ Grand Junction, CO 81506 98W 604-12-13 Annex r Storage Area Proposed Storage Areas Access Road Map Revised: Nov 3, 2014 Garfield County, Colorado 0 0.5 1 1.5 2 2.5 Miles 697-16-16 Annex Storage Area 98W 97W 96W 96W Proposed Storage Areas StorageAreaAccessRoad Unimproved Public Road Gravel Public Road 01%0 Paved Public Road 41%," Interstate 70 LEGEND: • Gas Well Location Structural Contour Tu - Uinta Formation Tge — Green River Formation Evacuation Creek Member Tgp — Green River Formation Parachute Member m Mahogany Bench Tgg — Green River Formation Garden Gulch Member 4.1 • PROJECT NO: 014-2740 DRAWN BY: JWH DATE: 01/22/2015 OXY Cascade Creek 697-16-16 Annex Geologic Map Section 16, 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 ; DougII2-Plataiu Arra, Colorado, Parti of Garfield and Men Counties (00682) Map Map Unit Meme Acres Percent Unit In of AOL Symbol AOL 46 Happle-Rockcutacp 7.1 4.2% association, 25 to 65 percent slopes 52 Narthwater-Adel complex, 5 372 21.9% to 50 percent slopes 56 Parachute-Iri9ul-Rhone 124.6 73A% associatiohn, 25 to 50 percent slopes 71 Utso-Rack outcrop complex, 0.9 0.5% 40 to 90 percent slopes Totals for Area of I me rest 1 .7 1110.0% Map adapted from the USDA NRCS Websoil Survey PROJECT NO: 014-2740 DRAWN BY: JWH DATE: 01/22/2015 OXY Cascade Creek 697-16-16 Annex Soils Map Section 16, T6S, R97W, 6 P.M. Garfield County, Colorado OLSSON ASSOCIATES 4690 Table Mountain Drive Golden, Coloraado 80403 TEL 303.237.2072 FAX 303.237.2659 FIGURE S-1 LEGEND: • Gas Well Location Permitted Water Well Location .9 Spring Location Intermittent Stream Location ACAIFy-9": V�F.'4•�•Gv .�1 'Cf EEK -61C1-22-43 eek, . 97-O8 ek 697-08=,4 ek 1197-CiBr 37A'• CA_ 6s4adpeC7tsi?LLk 6 7-0$-35A scae Creek 7-0A3-§, 8 Eascade Creek 637-q8;& ,CA$CADE'CREE K697 s FCescade r,ek.19-�••7- -2r KAP Castada 7;L18-2 c 61--46'x' / / Cad,ree,C'69 Casca • '-ekOcAr CFRE 0 ; ,}. t .•CA Ct4 cRE e" Creek 697-08-54A C ssa r k $97}0 9019911 7-17-23A _ Fees,3de c•48,444•697 4 QASCAD "CRE�FIfff 7-4 • 7 E'r 1.'P -1`13.:P-39 • GAS ` Cad `"Cre4k -CAS GR t 7 1 11 A - • .' 0.-42V a�saCfeelc � - • 0-426 Cascade Creek 6971 1--,.O1 Cascade Cr'ek 15=1'1 G'DE .CREEK Fj94715D 1 t GAgp jb ' • REf ADE c'RVEk'` j1-,0 ---- CAOE 1 RFPR697,15- 4 '- CASCAISE EEK 69�� ;1$-"3C 116-1$D fa. .r;�.� e�� - �. , , , {CASCADE Cf EK 6973-15-3117.-4, CASE CF,EEK {99715.2 4-46;--2-8k------ , -_-_-- , �%,`�f' CASCADEt•Reit q97-ii5 z A ,'''IR: ebb -1,5:2, 11697-15 u 16y Fledvr ; IA �, ,�' •• r' r ✓.- ' t 637/5-57 1 Oxy F. edetl 697-15-6A 697715-444 , 'G FeUeral 69771 .42B. - r I` JCA5C+91DE CREEK 697 16-29b CA.;?CAO GIS 46 c Gascaue Gree _r 7 1x7 54g ��r :' l l S A 'C E C,`, 4$A 1 i a cade Creek 697-''£}-291 'i •ascad- C(-.- 48B . •G`ascade CreerlE 697. 7 Pcde Crega, 696-1 tt��sca . \, Cas Creek 697-: • A SCAQE CREAK 69 -16-1.7$ I. -CA3C DE CRE] (4.797-1. CASCADE CREK697 ade Cr ek+697-17 54A , ��� $ 5 69746,4901 CASCA[ 'GREEK 697% C. • • ! 5 4'ti'c,7 %C li ./ EC EEK 6.97 -16 -Std CAISCAf3 1 � yr 4 Gi?}Y FEIDERAL•21-i5• Cascade Creek 7-15.4 �• _Cascade Creek Cascade C' reek 697-15 1 t ascacic CFee Cascade Creek, 697-15,66 , -Cascade Cree1E- 4pYitt.[jY t 1144" r y Sri. 15=,39 750 i }SOD 3000` + rri -� -fir?'" `P• { CSC'6 6tc7.2L�k• -R, • - t.(• PROJECT NO: 014-2740 DRAWN BY: JWH DATE: 01/22/2015 OXY Cascade Creek 697-16-16 Annex Surface Water and Hydrologic Map Section 16, T6S, R97W, 6 P.M. Garfield County, Colorado ON, OLSSON ASSOCIATES 4690 Table Mountain Drive Golden, Colorado 80403 TEL 303.237.2072 FAX 303.237.2659 FIGURE SWH-1 " OXY USA WTP LP OXY 760 Horizon Drive, Suite 101 Grand Junction, CO 81506 - 697-16-16 Annex Storage Area Floodplain Map Revised: Oct 20, 2014 0 1 2 Garfield County, Colorado 3 4 Miles 697-16-16 Annex Storage Area l Floodplain - 697-16-16 Annex Storage Area Oxy responsible road Unimproved Public Road Gravel Public Road Paved Public Road