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HomeMy WebLinkAbout1.17 Geohaz ReportArticle 4-203.G.4 Geologic and Soils Hazard Report Ursa Operating Company Battlement Mesa Land Investments Major Impact Review Application Battlement Mesa PUD Phase I BMC D OAProject No. 014-1829 NATURAL AND GEOLOGIC HAZARDS ASSESSMENT REPORT URSA OPERATING COMPANY BMC D PAD WELL SITE E 1/2, NW 1/4 SECTION 18, T7S, R95W, 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 OCTOBER 2014 PROJECT No. 014-1829 O\OLSSON ASSOCIATES 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, last amended September 2, 2014. 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 Ursa Operating Company BMC D Pad Garfield County, CO Olsson Associates Golden, Colorado October 2014 A search of the Colorado Department of Regulatory Agencies (DORA) Licensed Professions 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, and the term "Professional Geologist" is 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 Ursa Operating Company BMC D Pad Garfield County, CO ii Olsson Associates Golden, Colorado October 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 BMC D Pad Well located in the E 1/2 NW 1/4 Section 18, Township 7 South, Range 95 West, 6th Principal Meridian in Garfield County, Colorado (Parcel #240708100152). - 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 Texas, 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. Prepared by: Reviewed by: James W. Hix, PG Kevin J. Taylor, PG Senior Geologist Senior Geologist Date: 10/03/2014 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 Ursa Operating Company BMC D Pad Garfield County, CO Olsson Associates Golden, Colorado October 2014 TABLE OF CONTENTS Natural and Geologic Hazard Report Preface Professional Geologist Certification TABLE OF CONTENTS iv FIGURES iv 1.0 EXECUTIVE SUMMARY 1 2.0 GENERAL SITE LOCATION AND BACKGROUND 3 2.1 Project and Site Description 3 2.2 Structural Geology 3 2.3 Site Geology 4 2.4 Soil 4 2.5 Hydrologic Setting 5 2.6 Aquifers 5 3.0 NATURAL AND GEOLOGIC HAZARD ASSESSMENT 6 3.1 Utilities 6 3.2 Avalanche Hazard Area 6 3.3 Landslide Areas or Potential Landslide Hazard Areas 7 3.4 Rockfall Areas 7 3.5 Alluvial Fan Hazard Areas 7 3.6 Unstable or Potentially Unstable Slopes 7 3.7 Corrosive or Expansive Soils and Rock 8 3.8 Mudflow and Debris Fan Areas 8 3.9 Development Over Faults and Risk of Seismic Activity 8 3.10 Flood Prone Areas 9 3.11 Collapsible Soils 9 3.12 Mining Activity 9 3.13 Radioactivity 10 4.0 Conclusions and Recommendations 11 5.0 References 12 FIGURES List of Figures Adjacent Land Use Map Geology Map NRCS Soils Map Topographical Map Showing Surface Water Floodplain Map Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO iv Olsson Associates Golden, Colorado October 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 BMC D production well pad located in the, E 1/2 NW '/4 Section 18, Township 7 South, Range 95 West, of the 6th Principal Meridian, Garfield County, Colorado. The Site is at an elevation of about 5,280 feet above mean sea level (amsl). The site setting is shown on the attached BMC D Adjacent Land Use 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. The soils in the vicinity of the Site are corrosive to steel and moderately corrosive to concrete due to high salt content. The soils have a low to moderate shrink -swell potential so expansive soils are not considered a hazard affecting the Site. According to the Preliminary Geologic Map of the Grand Valley Quadrangle, Garfield County, the proposed Site is located on Quaternary age (Holocene) mud flow and fan gravel deposits. These are related to prehistoric flow associated with Battlement Creek. The Site is not mapped as being in an Alluvial Fan Hazard area, but is located on alluvial fan deposits associated with Battlement Creek and unnamed intermittent drainages. The Site is not mapped within the FEMA 100 -year flood plain, but is located within 650 feet of the Colorado River. There is an unnamed drainage 520 feet to the northeast and another unnamed drainage 760 feet southwest of the BMC D Pad. The areas immediately adjacent to the banks of these drainages are prone to flash floods. Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO 1 Olsson Associates Golden, Colorado October 2014 The BMC D Pad 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 Ursa Operating Company BMC D Pad Garfield County, CO 2 Olsson Associates Golden, Colorado October 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 BMC D Well Pad. The proposed facility will be used to drill for and produce natural gas. 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 BMC D well pad site is located to the south of the town of Parachute, Colorado off of County Road 300. The site is located in the E 1/2 NW '/4 Section 18, T7S, R95W, 6th P.M. and is located in parcel # 240913406004. The surface land is owned by Battlement Mesa Partners. The site is located west of the intersection of Battlement Parkway (County Road 300) and River Bluff Road (County Road 302), in the community of Battlement Mesa. 2.2 Structural Geology The BMC D 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. 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 Ursa Operating Company BMC D Pad Garfield County, CO 3 Olsson Associates Golden, Colorado October 2014 2.3 Site Geology According the Preliminary Geologic Map of the Grand Valley Quadrangle (Donnell, Yeend, Smith, 1986), bedrock mapped to the east of 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 mud flow and fan gravel deposits. Weak claystone in the upper Wasatch Formation are responsible for the slope failure which resulted in slides and debris flows during a time when the climate was much wetter. These mudflow and fan gravel deposits consist of pebble, cobble, and boulder gravel in a gray matrix of coarse sand. The unit is poorly sorted and contains angular to subangular clasts of primarily unweathered basalt, but contains some sandstone, marlstone, siltstone, and claystone. The unit was largely derived from solifluction deposits located to the east of the quadrangle. Modern alluvium, alluvial, and floodplain deposits consisting of mud, silt, sand, and gravel are also present along the Colorado River drainage covering the fan gravel deposits in the vicinity of the site. The alluvial and floodplain sediments are locally derived from coalescing fan deposits and sheet -wash deposits form terraces along the active Colorado River drainage, and also contain well-rounded, well -sorted, non -locally derived crystalline rocks transported from areas to the east. The gravel commonly ranges in thickness from 10 feet to 60 feet thick; however, it is locally up to 100 feet thick, especially near the Colorado River (Yeend, 1969). Alluvial terrace and fan gravel deposits are present to the southwest of the site and in the northeast corner of Section 18. These deposits consist of grayish brown sandy -gravel consisting primarily of basalt and locally derived slabby siltstone, marlstone, and sandstone clasts that are moderately to poorly sorted, poorly stratified. The maximum thickness of this unit reaches 200 feet. 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 BMC D well pad: Potts Loam, 6% to 1% slopes, Map Symbol 56: The Potts loam is a deep, well drained, moderately sloping to rolling soil formed on mesas, benches, and the sides of valleys at elevations between 5,000 feet and 7,000 feet above mean sea level. The Potts loam soil formed in alluvium derived from sandstone, shale, or basalt. Typically the surface layer is a brown loam about four inches thick, the subsoil is a reddish brown clay about 24 inches thick, and the substratum is a pinkish white loam to a depth of 60 inches. Permeability is moderate, and available water capacity is high. Surface runoff is medium, and the erosion hazard is severe. The Potts loam soil is corrosive to steel and moderately corrosive to concrete. Community development is limited by low strength, shrink -swell potential, and slopes. Buried piping and structures onsite will need to have adequate cathodic protection to prevent corrosion due to the salinity of these soils. Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO 4 Olsson Associates Golden, Colorado October 2014 2.5 Hydrologic Setting The site is located on a terrace approximately 180 feet above the Colorado River flood plain. The Colorado River is located approximately 650 feet to the north-northwest. The Monument Gulch creek drainage is located approximately 4,000 feet to the southwest. There is an unnamed intermittent drainage 520 feet to the northeast of the site, and another unnamed intermittent drainage located approximately 760 feet to the southwest of the site. These surface water features are shown on the Surface Water Map. Battlement Creek is located approximately 2.5 miles to the northeast. 2.6 Aquifers The Wasatch Formation locally yields water to wells in some areas, but is generally considered a confining unit. The Tertiary sedimentary rocks in the Piceance Basin are generally fine- grained and well cemented resulting in very small hydraulic conductivity in the rock matrix. Sandstone and siltstone generally occur in lenticular bodies and locally have moderate hydraulic conductivities ranging from 0.001 to 0.01 feet per day. These lenses of sandstone and siltstone are often widely spaced and not interconnected which further limits the volumes of groundwater the formation can yield to wells. In some areas, fracturing during the structural deformation that occurred when the Piceance Basin was uplifted and through dissolution of cementing minerals has enhanced the permeability and hydraulic conductivity in parts of the Piceance Basin aquifer system (Topper et al, 2003). Water well depths in the area typically range from 250 feet to 300 feet below ground surface (bgs) along the terraces above the Colorado River. Static water levels reportedly range between 20 feet and 60 feet bgs based on a review of permitted water wells in the vicinity of the site. Surficial aquifers are present in the alluvium along the Colorado River and its major tributaries. The depth to groundwater is expected to be less than 20 feet in close proximity to the Colorado River. This alluvium is typically too thin, narrow, and discontinuous to be considered a major aquifer, although in some areas the alluvium is locally important as surficial aquifers (Banta and Robson, 1995). Groundwater within the unconsolidated sediments in the area of the proposed site is controlled by the thickness of the sediments and the depth to the top of the Wasatch bedrock. The estimated groundwater flow direction in the vicinity of the site 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. Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO 5 Olsson Associates Golden, Colorado October 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 Adjacent Land Use Map shows the location of the BMC D Well Pad 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 will be based upon the recommendation and requirements of the utility service provider and approved by the County. Except for potential flash flooding, above- ground utilities, such as transformers, are not expected to be affected by geologic or other natural hazards. Trenches for water pipelines and natural gas pipelines are expected to be associated with the proposed development. The slope of the Potts soil 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. River Bluff Road (County Road 307) is located to the west of the site. Housing developments are located to the east, northeast, and southeast of the site. The Battlement Mesa waste water treatment facility further to the southwest 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 natural gas well site since it is located at an elevation of approximately 5,280 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). Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO 6 Olsson Associates Golden, Colorado October 2014 3.3 Landslide Areas or Potential Landslide Hazard Areas The site is located on mudflow and fan gravel deposits. There are earthflow and soil creep deposits mapped to the south of the site in southern half of Section 19, but these deposits are not mapped in Section 18, Township 7 South, Range 95 West. Movement of the extensive earthflow and soil creep slopes has ceased, except for local occurrences of very recent slumps and mudflows. Solifluction deposits are extensive in the Rulison 7.5 -minute quadrangle located to the east, but are only found in a small area on the east side of the Parachute (Grand Valley) 7.5 -minute quadrangle (Yeend, Donnell, Smith, 1986). According to Map 24 — Surface Geology map, Geologic Hazards Identification Study (Lincoln Devore, 1975-1976), there are no landslides shown to the south of Interstate 70 in the Parachute — Battlement Mesa area. Landslide areas are shown to the northwest of the town of Parachute (Garfield County, Surface Geology, 2007). 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 are present along the steep drainages incised by Monument Creek to the south and southeast or at higher elevations to the south on Battlement Mesa. 3.5 Alluvial Fan Hazard Areas The site is not mapped as being in an alluvial fan hazard area according to the Garfield County Surficial Geology, 2007. However, the site is located on an alluvial terrace underlain by fan gravel deposits and mudflow according to the Preliminary Geologic Map of the Grand Valley Quadrangle (Donnell, Yeend, Smith, 1986). The historic mudflows and fan gravels are associated with the Battlement Creek drainage located approximately 2.5 miles to the northeast. These fan gravel and mudflow deposits lie about 100 feet above the modern Colorado River flood plain. 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 show the area south of the Colorado River and in the vicinity of the site as being identified in a slope hazard area. 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 Loam soils are found on 6% to 12% slopes. Engineering, design, and construction practices of the proposed well pad development are expected to mitigate the limitation of slopes at the site. The site is located within an area developed for other land uses, including housing developments located to the east, northeast, and southeast of the BMC D well pad. Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO 7 Olsson Associates Golden, Colorado October 2014 3.7 Corrosive or Expansive Soils and Rock According to the Soil Survey of the Rifle Area, the Potts loam soils are corrosive to steel and moderately corrosive to concrete. Sedimentary rock containing high salt content, such as chloride or sulfate, and soils derived from these rock types, may also be corrosive to concrete or metal, causing damage to structures built upon them. The Potts loam is slightly acidic to alkaline with pH ranging from 6.6 to more than 8.4 standard units. The salinity in the Potts loam is typically less than 2 millimhos per centimeter (mmhos/cm). Some Tertiary and Cretaceous age sedimentary rocks with high clay content are capable of accepting water into their chemical structure and expanding 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 shrink swell potential of the Potts loam is considered low to moderate. 3.8 Mudflow and Debris Fan Areas The site is located in an area of mud flow and fan gravel deposits partially overlain by alluvial terrace deposits. The site is located on a terrace near the Colorado River drainage. These deposits are Holocene in age and future mud slides are a potential hazard if the area were to receive heavy rains. These flows are expected to originate from higher elevations to the south and would follow the drainages to lower elevations closer to the Colorado River floodplain. Wetter conditions at the end of the last ice age were most likely responsible for the development of the extensive mudflows and fan deposits peripheral to Battlement Mesa and were deposited by historic flows from Battlement Creek. Glacial conditions that existed on the Grand Mesa during the Pleistocene did not exist on Battlement Mesa at this time. Abundant annual runoff is suspected in creating high pore -water pressures within the Wasatch Formation shale and claystone to cause slope failure, especially on north -facing slopes where evaporation was at a minimum (Yeend, 1968). More recent slumps and mud flows have occurred south of Plateau Creek near the town of Collbran. These slumps and mud flows developed in glacial till. The proposed BMC D Pad is located on an undeveloped parcel east of River Bluff Road (County Road 307) to the south and east. The Battlement Mesa waste water treatment facility is located further to the southwest of the site. There are housing development located to the northeast and southeast of the site. 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 Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO 8 Olsson Associates Golden, Colorado October 2014 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. 3.10 Flood Prone Areas The site is not shown within the FEMA 100 year flood hazard zone based on the Flood Plain Map in the Vicinity of the Town of Parachute, Garfield County, Colorado, or a Firmette Map generated from the FEMA data. The Colorado River flood plain is located approximately 650 feet to the north of the site at an elevation that is approximately 180 feet lower than that of the site. The unnamed drainages located 520 feet to the northeast and 760 feet to the southwest are shown as having Zone A — 100 -year flood plains located along their banks. These areas are also prone to flash floods. The flood plain along the Colorado River is shown in relation to the BMC D Pad on the attached Flood Plain 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 BMC D Pad 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. Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO 9 Olsson Associates Golden, Colorado October 2014 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 before 1954, and most of that came from the Rifle and Garfield mines. Both of these mines were 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). 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 Ursa Operating Company BMC D Pad Garfield County, CO 10 Olsson Associates Golden, Colorado October 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 BMC D Pad located in Garfield County, Colorado. Geological hazards are not expected to be associated with the installation of buried utilities at the BMC D Pad. Corrosive soil may be a limitation to this construction, but this limitation should be able to be overcome with proper engineering, design, and construction. Cathodic protection for buried piping may reduce corrosion resulting from salts in these soils. Avalanche conditions are not expected to be a hazard in the area of the site. The site is located on an alluvial terrace and is underlain with mud flow and fan gravel deposits. The site is within the town limits for Battlement Mesa, and there are housing developments to the east, northeast, and southeast of the site. The mud flow, terrace, and fan gravels are not expected to constitute a geologic hazard for the BMC D Pad development. Rockfall areas are not present in the area of the site, and are not expected to be a geologic hazard affecting the site. The site is not in an area mapped as an alluvial fan hazard area; however, the site is underlain by alluvium and fan gravels. The site is underlain by mud flow and fan gravels that were deposited during prehistoric times from floods associated with Battlement Creek. Alluvial fans have been deposited at the mouths of Battlement Creek, Monument Gulch, and other nearby streams. Slope is a not expected to be a geologic hazard affecting development of the BMC D Pad site. The Potts loam soils are corrosive to steel and moderately corrosive to concrete and the subsoil has a high shrink -swell potential. The Potts loam is listed as having low to moderate shrink -swell potential, so expansive soils are not expected to pose a hazard affecting the proposed BMC D Pad site. Collapsible soils are not present in the vicinity of the proposed BMC D Pad site. No significant faults have been mapped or are known in the BMC D Pad site. The site is not mapped as being within the 100 year flood plain. Flash flooding is a hazard for lower elevations along the unnamed drainages to the northeast and southwest of the proposed Site and along the Colorado River. Areas immediately adjacent to these streams are located within the 100 year flood plain and 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 Ursa Operating Company BMC D Pad Garfield County, CO 11 Olsson Associates Golden, Colorado October 2014 5.0 References Cashion, W.B., 1973, Geologic and Structure Map of the Grand Junction Quadrangle, Colorado and Utah, USGS, Map 1-736, 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. Yeend, W.E., 1969, Quaternary Geology of the Grand and Battlement Mesas Area, Colorado, USGS Professional Paper 617, 50 p, 1 plate. Online References Colorado Oil and Gas Conservation Commission http://cogcc.state.co.us/ Natural Resources Conservation Service - Soil Survey http://www.nres.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://geosurvev.state.co.us/hazards Colorado Geological Survey website: http://geosurvey.state.us/land/Pages/Professional Geologist Colorado Department of Public Health and Environment: http://co- radon.info/CO radon map.html Geologic Hazard Report Ursa Operating Company BMC D Pad Garfield County, CO 12 Olsson Associates Golden, Colorado October 2014 FIGURES BMC D Pad Surf EXEMPT -STATE -LAND-NONRES /' SPEC. PURPOSE -LAND • I I • SINGLE FAM.RES.-LAND i VACANT COMMERCIAL LOTS • 1500'. 07 Q\ PO o� ;c`• F VACANT 10 AC 41e� ^ ,�� •�'•s� `.. PUD LOTS TO L/T .' ey35 AC C EXEMPT ALL R zO OTHER LAND SINGLE FAM.RES-IMPROVEMTS• ♦• • ` /. RECREATION IMPROVEMENTS /•♦ / •1 /EXEMPT ALL / OTHER LAND Proposed BMC D Pad -List SINGLE PJ FAM.RES-IMPROVEMTS EXEMPT ALL OTHER LAND VACANT COMMERCIAL LOTS • •EXEMPT ALL OTHER LAND I • EXEMPT -COUNTY -LAND I• • \ .1 •0•\._ 5ACTO L/T 10 AC EXEMPT ALL OTHER LAND— SINGLE AND — . . Adjacent Land Use 10 AC TO L/T 35 AC 5 AC TO L/T 10 AC EXEMPT ALL OTHER LAND EXEMPT -COUNTY -LAND EXEMPT-STATE-LAND-NONRES MULTI-UNITS(9 +)-IMPRVMTS RECREATION -IMPROVEMENTS SINGLE FAM.RES-IMPROVEMTS SINGLE FAM.RES.-LAND SPEC.PURPOSE-LAND VACANT COMMERCIAL LOTS VACANT PUD LOTS Proposed BMC D Pad County Road Proposed BMC D Pipeline QTownship OSection DISCLAIMER This Geographic Information System (GIS) and its components are designed as a source of reference for answering 0 250 inquiries, for planning and for modeling. GIS is not intended, nor does it replace legal description information in the chain of title and other -� information contained in official government records such as the County Clerk and Recorders office or the courts. In addition, the representations of locations in this GIS cannot be substituted for actual legal surveys. Feet A 500 Project Number: 014-1829 Drawn By: JWH Revision Date: 9/30/2014 Adjacent Land Use Map Ursa Operating Company BMC D Pad Garfield County, CO Sec 18, T7S, R95W, 6th PM Ursa OPERATING COMPANY Figure ALU -1 Proposed BMC D PadCounty Road PUDPhasel_Pipeline Hydrography QTownship - ;- Intermittent Stream OSection 100/500 Year Combined Floodplain DISCLAIMER This Geographic Information System (GIS) and its components are designed as a source of reference for answering 0 inquiries, for planning and for modeling. GIS is not intended, nor does it replace legal description information in the chain of title and other information contained in official government records such as the County Clerk and Recorders office or the courts. In addition, the representations of locations in this GIS cannot be substituted for actual legal surveys. 250 500 Feet A Project Number: 014-1829 Drawn By: JWH Revision Date: 9/30/2014 100/500 Year Floodplain Map Ursa Operating Company BMC D Pad Garfield County, CO Sec 18, T7S, R95W, 6th PM Ursa7S,TING R95W Figure FP -1 • • HYDROGRAPHY: FEATURE PRESENT WITHIN 1,000 ft Ditch Floodplain Groundwater Depth Intermittent Stream Perennial Stream Riparian Area Spring Water Body Watershed Water Well Wetland No Yes - 622 ft Approx. 130 Yes - 301 ft Yes - 785 ft No No No No No No Notes / Comments: o .0 1,000 Feet Ursa OPERATING COMPANY Form 2A - Attachment E Topographic Map Showing Surface Waters BMC D 39.44145 -108.04075 Section 18, Township 7 South, Range 95 West Proposed Development County Roads = Proposed Access — Local Roads HRL COMPLIANCE SOLUTIONS, INC. Environmental Consultants Author: M. Spinelli Revision: 2 Date: 3/10/2015 NRCS SOILS KEY: Notes / Comments: MAP SYMBOL SERIES NAME 3 Arvada loam (1-6% slopes) 4 Arvada loam (6-20% slopes) 34 Ildefonso stony loam (25-45%) 51 Olney loam, (6-12% slopes) 55 Potts loam (3-6% slopes) 56 Potts loam (6-12% slopes) 58 Potts-Ildefonso complex (12-25%) 65 Torrifluvents (nearly level) 72 Wann sandy loam (1-3% slopes) 73 Wann sandy loam (3-6% slopes) Feet w0 1,000 Ursa OPERATING COMPANY Form 2A - Attachment H NRCS Soils Map BMC D 39.44145 -108.04075 Section 18, Township 7 South, Range 95 West Approx. Center Proposed Development Proposed Access County Roads — Local Roads tt RL COMPLIANCE SOLUTIONS, INC.I Environmental Consultants Author: M. Spinelli Revision: 0 Date: 3/10/2015 Attachment H — NRCS Soil Survey, Rifle Area Map Symbol 56 — Potts loam (6-12% slopes) Deep, well drained, moderately sloping to rolling soils found on mesas, benches and valley sides. Elevation 5,000 to 7,000 feet Average Annual Precipitation Approximately 14 inches Average Annual Air Temp Approximately 46 degrees F Frost Free Days Approximately 120 days Permeability Moderate Available Water Capacity High Effective Rooting Depth 60+ inches Surface Runoff Medium Erosion Hazard Severe Native Vegetation: Mainly wheatgrass, needleandthread, and sagebrush. Development is limited by low strength, shrink -swell potential, and slope. This soil is in capability subclass We, irrigated and nonirrigated. Map Symbol 58 — Potts-Ildefonso complex (12-25% slopes) Strongly sloping to hilly soils found on mesas, alluvial fans, and valley sides. Elevation 5,000 to 6,500 feet Average Annual Precipitation Approximately 14 inches Average Annual Air Temp Approximately 46 degrees F Frost Free Days Approximately 120 days Permeability Moderate Available Water Capacity Low Effective Rooting Depth 60+ inches Surface Runoff Medium Erosion Hazard Moderate Native Vegetation: Mainly wheatgrass, needleandthread, and sagebrush. Development is limited by steep slopes and structures are needed to divert runoff. This soil is in capability subclass VIe, nonirrigated. 1829\GIS\MXD\G-1 6 EQUIVALENT Proposed BMC D Pad County Road Proposed BMC D Pipeline Hydrography Township Intermittent Stream QSection DISCLAIMER This Geographic Information System (GIS) and its components are designed as a source of reference for answering 0 inquiries, for planning and for modeling. GIS is not intended, nor does it replace legal description information in the chain of title and other information contained in official government records such as the County Clerk and Recorders office or the courts. In addition, the representations of locations in this GIS cannot be substituted for actual legal surveys. 250 500 Feet A Project Number: 014-1829 Drawn By: JWH Revision Date: 10/10/2014 Geology Map Ursa Operating Company BMC D Pad Garfield County, CO Sec 18, T7S, R95W, 6th PM UrsaCOMPANYG Figure G-1