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Home My WebLink About20152976 3 'EE 14 EARTH ENGINEERING CONSULTANTS, LLC May 5,2015 (Revised May 6,2015) Great Western Development Co. 2005 Howard Smith Avenue East Windsor, Colorado 80550 Attn: Mr. Erik Halverson(ehalversona'omnitrax.com) Re: Geologic Hazards and Mineral Extraction Evaluation Maan If Property —Great Western Industrial Park Weld County, Colorado EEC Project No. 1152044 Mr. Halverson: Earth Engineering Consultants, LLC (EEC) personnel have completed the geologic hazards and mineral extraction evaluation you requested for the referenced project. That evaluation was completed by reviewing readily available data concerning soil and groundwater conditions at the site, principally through review of United States Geological Survey (USGS)/Colorado Geological Survey (CGS) and United States Department of Agriculture Soil Conservation Service (SCS) published infonnation. A listing of the references reviewed as a part of the geologic hazard study is included with this report. A site observation of the property and surrounding area was performed on May 4, 2015. Maan II Property includes approximately 66 acres of land located within the East Half of the Northeast Quarter of Section 25, Township 6 North, Range 67 West of the 6`h Prime Meridian, Weld County, Colorado. It is our understanding 66 acre site is currently being rezoned with no development plans as of yet. The purpose of this evaluation is to identify potential geologic hazards and potential mineral resources which may conflict with proposed future development. The conclusions and recommendations presented in this report are based upon the acquired field data, review of the available literature, and previous experience with similar geologic conditions in this area. 4396 GREENFIELD DRIVE WINDSOR, COLORADO 80550 (970) 545-3908 FAX (970) 663-0282 Yd- - t ty-: =e ce s r -"�`c`,`a s� Earth Engineering Consult nts,LLC EEC Project No, 1152044 May 5,2015 (Revised May 6,2015) Page 2 Slopes on the site are generally gentle to the east-southeast. A small irrigation ditch was observed within the central portion of the property oriented north-south. The property currently appears to be primarily agricultural farm land, although no evidence of recent farming activity was noted during our site visit. The west and south side of the property is defined by County Road 23%and County Road 64%, respectively. The Colorado and Southern Railroad defines the northern property boundary and an agricultural field defines the east property boundary. industrial property, consisting of Vestas Blades America and Brockway Glass Container, was observed to the west of the Maan it property. Several single family residential buildings are located east and south of the proposed development parcel. One abandoned oil/gas well is located within the proposed Maan II property. RESEARCH Soil/Geologic Review The site geology presented in this report is based upon the acquired field data, review of the available literature and maps, and previous experience with similar geologic conditions in this area. The locations of geologic features are approximate and should he considered accurate only to the degree implied by the methods used to make those measurements. The project site lies in the Colorado Piedmont Section of the Great Plains Physiographic Province. The sediments which compose the Colorado Piedmont were formed when uplift of the present day Rocky Mountains in Eocene-Late Cretaceous times (30-70 million years ago) produced a large increase of stream sediments resulting in deposition of sediments on the flanks next to the mountain belt and outlying areas. The Colorado Piedmont is an elongated trough in the Great Plains, adjacent to the Front Range of the Southern Rockies. The Colorado Piedmont was formed when uplift of the area in Miocene times (5-20 million years ago) produced an increase of stream erosion resulting in scouring next to the foothills and outlying areas. The Piedmont is bordered by the southern Rockies to the west, Great Plains escarpment to the northeast,and Palmer Divide to the south. Earth Engineering Consultants,L.I.C EEC Project No. 1152044 May 5,2015 (Revised May G,2015) Page 3 Structurally, the site lies within the Denver Basin, a thick accumulation of Paleozoic and Mesozoic Era sediments involved with down-warping in the basin area and uplift of the adjacent highlands. Small anticlinal folds occur adjacent to the Front Range. It is our understanding that faulting has not taken place in the recent historic past in this area. The site was visually inspected on May 4, 2015. The U.S Geological Survey describes the bedrock underlying the site consisting of the Fox Hills Sandstone (Upper Cretaceous) Formation (Kfli). The Fox Hills Sandstone generally consists of a massive pale yellow fine grained sandstone, interbedded claystones and siltstones are common towards the bottom of the formation. The bedrock is covered by alluvial and mixed alluvial deposits. The United States Department of Agriculture Soil Conservation Su.rveyW map describes the surficial soils mainly as fine sandy loams and clay loam. The surficial soils are generally classified as exhibiting low erosion potentials with no to low shrink/swell potential. In general, the near surface soils at this site appear to range from low plasticity clay and clayey sand soils to non-plastic granular sands with varying amounts of silt. Areas of non-cohesive to low cohesive materials exist on the parcel and may be susceptible to erosion. A geotechnical investigation should be conducted at each proposed building site to identify if these conditions exist. POTENTIAL GEOLOGIC HAZARDS AND RECOMMENDATIONS Coal Mines A review of the Geologic Hazard Area Map of Potential Ground Subsidence Areas in Weld County, Colorado`', Colorado Front Range .inactive Coal Mine Data And Subsidence Information Weld County''', and the Map Showing The Extent Of Mining, Locations of Mine Shafts, Adits, Air Shafts, And Bedrock Faults, And The Thickness Of Overburden Above Abandoned Coal Mines In The Boulder-Weld Coal Field, Boulder, Weld, And Adams Counties, Colorado(4) indicate past coal mining has not occurred on this parcel. The nearest known historical coal mine operations is located approximately 15 miles east of the property within the Cretaceous age I,aramie Formation. Coal resources likely do not underlie the proposed Maan 11 Property area. • Earth Engineering Consultants,L1..C EEC Project No. 1152044 May 5,2015 (Revised May 6,2015) Page 4 Oil and Gas Potential A review of the Colorado Oil and Gas Conservation Commission (COGCC)database(a Division of the Colorado Department of Natural Resources) and Oil and Gas Fields. Map of Colorado: Colorado Geological Survey Map Series 26. Maps of oil and gas well locations created by the COGCC indicate one (1) well (abandoned) on the site. The western portion of this property is underlain by the Lapoudre Field and the eastern portion of the property is underlain by the Bracewell Field. Based on the available information, it appears the well generally extend to the "J-Sands" on the order of 7500 feet below site grades. Production, as reported prior to abandonment, appeared to be both crude oil and natural gas. Flood Plain The Federal Emergency Management Agency Flood Insurance Map (panel 0802660605D and 0802660606C) for Weld County, Colorado indicates the site is located within Zone C 'Areas of Minimal Flooding'. We understand that an updated map panel is available, although presently under review for adaptation, from The Federal Emergency Management Agency Flood Insurance Rate Map (FIRM) Panel I 504E for Weld County, Colorado. Map Panel 1504E indicates the Maan H site is located within Zone A `Special Flood Hazard Areas(SFHA's)'. • Radiation A review of the available information from the Colorado Geologic Survey (a Division of the Colorado Department of Natural Resources) indicates that deposits of uranium oxide had been identified contained within the Fox Hills Formation, north and northeast of this location near the towns of Can and Keyota in Weld County. Although known deposits are considerably north of this site, the Fox Hills Sandstone Formation is located at depths below this parcel. At this time we anticipate no radiation hazards based on our understanding of these deposits and past land usage. However, we recommend that preliminary radon mitigation measures be incorporated in the construction of any buildings at the site and that homes/buildings be tested for radon after a normal living/operating routine has been established. Eurth Engineering Consultants,LLC EEC Project No. 1152044 May 5,2015 (Revised May 6,2015) Page 5 Uranium oxide can be extracted either by traditional removal (mining) methods or by a non- intrusive, in-situ mining operation. If future energy/military demand warrant collection of uranium and if uranium is present in sufficient quantities at depths underlying this site; surface development would not impede a non-intrusive extraction method of an economic resource. Sand, Crave! and Quarry Aggregate Resource The Atlas of Sand, Gravel, and Quarry Aggregate Resources-Colorado Front Range Counties- Colorado Geological Survey Special Publication 5-B, was used to gain a general overview of the property. The COS publication indicates that the parcel is within a Stream Terrace (i'4) aggregate source area. The COS indicates that gravel deposits are located approximately twenty four (24) feet below the ground surface and that the depth of the economic gravel is approximately eight (8) feet. Due to the limited size of this property, the existing infrastructure surrounding the property, the limited depth of gravel, and the stated depth below ground surface to the gravel resource would render the extraction of the deposits are not economically viable. CONCLUSION Based on the conditions observed and researched, there are no apparent significant geologic hazards on the property. Geotechnical investigations are recommended for each building site to identify shrink/swell potential in the soils and/or bedrock strata. Pre-mitigation radon control methods, such as sub-slab piping, as well as radon tests arc recommended. Based on these conditions and our observations, it is our opinion that the rezoning and/or future development of this parcel is compatible with the geologic conditions at the site. The data presented herein were collected to help determine the feasibility of this project. • Professional judgments on design alternatives and criteria are presented in this report. These are based on evaluation of technical information gathered, partly on our understanding of the characteristics of the development proposed, and partly on our experience with geologic conditions in the area. We do not guarantee the performance of the project in any respect, only that our geologic study and judgments rendered meet the standard of care of our profession. Gant,Engweericg C@ sahairs,CL.C 3:GC Project No. 1152044 Miay 5,2015 (Revised May 5,2013) Page 6 We appreciate the opportunity to be of service to you on this project If you have any questions or require additional information,please do not hesitate to contact us. Very truly yours, yy� Earth Engineering Consultants, EEC Reviewedby: '712 � s 1v 4X/I -Afrt6'15 CceSS/CiP, Gary J,Higgins, P.G, David A. Richer, P_E. Senior Engineering Geologist Senior Geotechnical Engineer GJILDARfdla Forth Engineering Consultants,LLC EEC Project No. 1152044 May 5,2015 (Revised May 6,2015) Page 7 REFERENCES I. Soil Survey Staff, Natural Resources Conservation Service,United States Department Of Agriculture. Web Soil Survey. Available at http://websoi lsurvey.nres.usda.govi accessed [May 4, 2015 J 2. The Weld County Department of Planning Services, May 10, 1978, Geologic Hazard Area Map Of Potential Ground Subsidence Areas In Weld County, Colorado: Colorado Geological Survey in cooperation with Amuedo And Ivey - Geological Consulting Engineers. 3. l urney, J.l . and Murray-Williams, L, 1983, Colorado Front Range Inactive Coal Mine Data And Subsidence Information. Weld County, Colorado: Colorado Geological Survey, Plate 12 of 12. 4. Roberts, S.B., Hynes, J.L. and Woodward, C.L.. 2001, Maps Showing The Extent Of Mining. Locations Of Mine Shafts, Adits, Air Shafts, And Bedrock Faults, And Thickness Of Overburden Above Abandoned. Coal Mines In The Boulder- Weld Coal Fields. Boulder, Weld And Adams Counties, Colorado. U.S.G.S., Geologic Investigation Series, Map I-2735 5. Colorado Oil And Gas Conservation Commission, COGCC GIS Online. Available at http://cogce.state.co.us/accessed [May 4. 2015] 6. Schwochow, S.D., Shroba, R.R. and Wicklein, P.C., 1974, Atlas Of Sand. Gravel And Quarry Aggregate Resources Colorado Front Range Counties: Colorado Geological Survey, Special Publication 5-B. Hello