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Home My WebLink About1.17 GeoHaz Rpt.pdfGeological and Soil Hazards Report OXY USA WTP LP Core Pad Storage OLSSON ASSOCIATES OA Project No. 013 -0867 760 Horizon Drive, Suite 102 1 Grand Junction, CO 81506 1 TEL 970.263.7800 1 FAX 970.263.7456 OLSSON ASSOCIATES GEOLOGIC AND SOIL HAZARDS REPORT Introduction Oxy USA WTP LP proposes to construct a Storage Facility to be located in the South half of Section 9, Township 6 South, Range 97 West, of the Sixth Principal Meridian, located north of the town of Debeque, and northwest of Interstate 70 and the Colorado River, in Garfield County, Colorado (Fig. Vicinity Map). The Core Pad Storage is located in the south - eastern part of the Piceance Basin, north of Cascade Creek on the Roan Plateau. The proposed location is shown on a map provided (Fig. G -1). Structural Geology The proposed project is located in the south - eastern part of the Piceance Basin; an irregularly - shaped elongated basin formed by tectonic forces associated with the Laramide orogeny that downwarped the earth's crust as a result of the uplift of the Colorado Rocky Mountains. Areas on all sides of the Piceance Basin have been uplifted by these same tectonic forces. 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). Numerous small sub - parallel northwest trending folds have been identified in the Green River Formation within the basin. The project site is situated near the east end of the axis of one such syncline. No significant faulting is known in the project area, but some jointing may occur in proximity to the folds. The Grand Hogback monocline, approximately 25 miles to the north -east, is a sinuous feature comprised of Upper Cretaceous age bedrock of the Mesaverde Group, which includes the Williams Fork Formation and the underlying Mancos Shale. The Grand Hogback forms part of the boundary between two major physiographic provinces, the Colorado Plateau and the Rocky Mountain foreland. Bedrock Geology Two bedrock formations crop out, or are exposed in the vicinity of the proposed facility, the (Eocene) Green River Formation and the (Eocene) Uinta Formation (formerly considered the Oxy USA WTP LP Core Pad Storage May 2013 1 Olsson Associates Grand Junction, CO OA Project # 013 -0867 Evacuation Creek Member of the Green River Formation). The Green River Formation underlies surficial deposits in most of the Roan Plateau uplands, and comprises the slopes and terraces near the project site. Rocks of the Green River Formation comprise the main bulk of the uplands of the Roan Plateau, and are exposed along the steep slopes and cliffs bounding the Parachute Creek canyon, as well as Piceance Creek and its numerous tributaries. The Green River Formation is comprised of lithified lacustrine sediment deposited in a group of intermontane freshwater Eocene lake basins in Colorado, Utah, and Wyoming. Over 3,000 feet of interbedded sandstone, mudstone, siltstone, limestone, dolomite, and marlstone were deposited in the deep lake known as Lake Uinta in very fine annual layers called varves. The Green River Formation is comparatively resistant to erosion, and comprises many of the high cliffs and escarpments surrounding the Parachute Creek valley. Three distinct Members of the Green River Formation are present near the project location. The basal unit of the Green River Formation is the Douglas Creek Member, predominately sandstone, limestone, and oolite from 430 to 470 feet in thickness, but is not exposed in the project area. The Garden Gulch Member, which is approximately 700 feet thick, forms the steep gray shale and marlstone cliffs and escarpments in the canyons below the project site. The light and dark gray banded strata at the tops of the steep slopes and cliffs below the project site are formed by the nearly 1,000 foot thick Parachute Creek Member, whose kerogen rich marlstone includes the Mahogany Bench, and is the primary `oil shale' source within the Green River Formation (Donnell). The Uinta Formation consists of thin layers of sandstone, siltstone, and volcanoclastic rocks deposited as ash -fall tuff and carbonate evaporite within Lake Uinta. Interbedding and interfingering of the Uintah Formation and the Green River Formation have made identification of the boundaries between the units subject to dispute by geologists for many years. The project site lies upon soils primarily derived from the weathering of the Uinta formation. Surficial Geology The proposed Compressor Station is located on Holocene soils consisting of silt, sand, and clay 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. Geologic Hazards The processes of erosion are the principal geologic hazards on the top of Roan Plateau, with landslide processes being the most widespread hazard. The site for the Storage Facility is located in an area of Garfield County that has been mapped by Garfield County for landslides or landslide potential, and no major slope hazards have been identified in the area. Landslides and rockfalls occur in areas that are vulnerable to slope failure due to a variety of reasons. Weak rocks, high relief, steep slopes, and locally abundant moisture are all contributing factors in causing landslides. Oxy USA WTP LP Core Pad Storage May 2013 2 Olsson Associates Grand Junction, CO OA Project # 013 -0867 Natural events, including intense rainfall, rapid snow melt, frost heaving, groundwater level changes, and earthquakes, in addition to human activities, may trigger landslides and rockfalls. Human activities which may cause failure include construction projects, the use of earth fill for construction, cutting benches into hill slopes, and use of unlined pits or septic systems that change water levels or add weight to the natural slope, increasing the shear stress. No mapped flood prone areas are indicated by Garfield County or FEMA floodplain mapping, though localized flash - flooding and seasonal inundation are not uncommon along the banks and tributaries of Conn Creek and Cascade Creek. According to the Colorado Geological Survey, there have been earthquakes in the eastern part of Garfield County near Glenwood Springs and New Castle, but there are no recorded earthquakes or faults shown in the immediate vicinity of the Core Pad Storage. Soils According to information prepared by the Natural Resources Conservation Service Soil Survey, soils in the project area have been mapped as the Parachute - Irigul complex (55), and Parachute - Irigul -Rhone association (56). The Parachute - Irigul complex (55) soils comprise the ridge -top upon which part of the Core Pad Storage will be built, as seen in figure S -1. The soils in this area occupy 5 to 30 percent slopes at elevations ranging from 7,600 to 8,800 feet above mean sea level. The Parachute - Irigul complex is a shallow and well- drained soil that forms on mountain tops. The capacity of the most limiting layer to transmit water is moderately low to moderately high. Depth to water table is more than 80 inches. The parent material is weathered marlstone and sandstone. Parachute - Irigul -Rhone association (56) soils comprise the 25 to 30 percent slopes on the flanks of the ridge upon which a portion of the Core Pad Storage will be constructed. The Parachute - Irigul -Rhone association soils are moderately shallow, well- drained soils generally comprised of weathered marlstone and sandstone. The capacity of the most limiting layer to transmit water is moderately low to moderately high. Depth to water table is more than 80 inches. Radon Radon is a naturally occurring, odorless and colorless radioactive gas that is produced by the radioactive decay of radioactive minerals present in the soils and bedrock. According to the Colorado Department of Public Health and Environment (CDPHE), Colorado has a moderate to high radon potential. Since the site is a facility that does not have buildings or an area that is occupied throughout the work day, the potential presence of radon is not expected to represent a geologic hazard or a significant worker exposure issue. Garfield County Geographic Information System Olsson personnel have reviewed the relevant county maps prepared by Garfield County's Geographic Information System (GIS) Department that pertain to this study. According to the Oxy USA WTP LP Core Pad Storage May 2013 3 Olsson Associates Grand Junction, CO OA Project # 013 -0867 Flood Plain Profile, the 100 -year flood plain is not shown to be in the vicinity of the Core Pad Storage. The Slope Hazard Map provided by Garfield County, Colorado - GIS Department website, does not include the area of this project, but no major slope hazard is likely within the immediate vicinity of the Core Pad Storage. The Surficial Geology Map provided by Garfield County, Colorado — GIS Department website does not include the area of this project, but no alluvial fan deposits are present in the project area, and no landslide, mudflow, mudflow /slide areas are likely within the boundary of this geologic study. Conclusions and Summary Although information provided by Garfield County, Colorado - GIS Department does not pertain to the location of the Core Pad Storage, the overall geologic and soil hazards appear to be low. With proper engineering, the proposed location should be safe for construction and operation of the Core Pad Storage. Stormwater controls and Best Management Practices (BMPs) should take into consideration the geology and soil types present at this location. These engineering controls and practices should be used temporarily and permanently to divert stormwater away from the construction areas and to prevent additional weight which could trigger landslide. Catchment basins should be sited and designed so as not to add weight to potentially unstable areas. zavi William Monroe, Associate Geologist Oxy USA WTP LP Core Pad Storage May 2013 4 Olsson Associates Grand Junction, CO OA Project # 013 -0867 References Donnell, John R., 1961, U.S.G.S. Bulletin 1082 -L, Tertiary Geology and Oil -Shale Resources of the Piceance Creek Basin Between the Colorado and White Rivers Northwestern Colorado. Grout, Marilyn A. and Verbeek, Earl 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. Harman, Jerry B. and Murray, Donald 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. Madole, Richard F. and Streufert, Randall K., 2003, Open -File Report 01 -2 Geologic Map of the Gibson Gulch Quadrangle, Garfield County, Colorado, Colorado Geological Survey, Department of Natural Resources, Denver, CO, 18 p. and accompanying map. 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 Oxy USA WTP LP Core Pad Storage May 2013 5 Olsson Associates Grand Junction, CO OA Project # 013 -0867 Oxy USA WTP LP Core Pad Storage May 2013 6 Olsson Associates Grand Junction, CO OA Project # 013 -0867 SHELL FRONTIER i OIL & GAS IVG LYLE 'PRATHER (1 /3)i NED PRATHER (1/3) 1' '',J RICHARD L. PRATHER (1/3) LYLE PRATHER (1/3) NED PRATHER (1/3) PUCKETTLAN LitgRIFFIN & ASSOCIATES, INC. 1414 ELK ST, ROCK SPRINGS, WY82901 (307) 362 -5028 VICINITY MAP DRAWN: 4/10/13 - DEH SCALE: 1" = 5000' REVISED: N/A JOB No. 15304 OXY USA, WTP LP. PROPOSED STORAGE LIMITED IMPACT REVIEW VICIIVITYMAP SECTION9, T.6 S., R.97 W., 6th P.M., GARFIELD COUNTY, COLORADO VICINITY MAP PROPOSED LOCATION D 1 EXISTING ROAD Legend Q Project Site Geology Type Tgp - Green River Fm., Parachute Creek Member Tu - Uinta Formation 0 250 500 Feet 1,000 3 PROJECT NO: 013 -0867 DRAWN BY: Jenna Muhlbach DATE: 7/24/2013 GEOLOGY MAP OXY USA WTP LP CORE PAD STORAGE GARFIELD COUNTY, COLORADO OLSSON ASSOCIATES 760 HORIZON DR., SUITE 102 GRAND JUNCTION, CO 81506 TEL 970.263.7800 FAX 970.263.7456 FIGURE G -1 Legend Project Site Soil Type 52 - Northwater -Adel complex, 5 -50% slopes 55 - Parachute - Irigul complex, 5 -30% slopes 56 - Parachute - Irigul -Rhone association, 25 -50% slopes 57 - Parachute -Rhone loams, 5 -30% slopes 63 - Silas loam, 1 -12% slopes 0 250 500 Feet 1,000 N PROJECT NO: 013 -0867 DRAWN BY: Jenna Muhlbach DATE: 7/24/2013 SOILS MAP OXY USA WTP LP CORE PAD STORAGE GARFIELD COUNTY, COLORADO OLSSON ASSOCIATES 760 HORIZON DR., SUITE 102 GRAND JUNCTION, CO 81506 TEL 970.263.7800 FAX 970.263.7456 FIGURE S -1