Characterization GEOLOGIC Prepared by ? TABLE OF CONTENTS Section Page 1.0 INTRODUCTION ....................................... 1 1.1 Purpose ........................................... 1 1.2 Scope of Characterization .............................. 1 1.2.1 Literature Search .... ........................... 1 1.2.2 Core Processing and Description ..................... 2 1.2.3 Reprocessing of Seismic Data ........................ 2 1.2.4 Grain Size Analysis .............................. 2 1.2.5 Geologic Report ................................ 3 1.3 Location and General Setting ...., ........................ 3 1.4 Previous Studies ...................................... 5 2.0 STRATIGRAPHY ....................................... 7 Precambrian ......................................... 2.1 7 2.2 Paleozoic And Mesozoic Sedimentary Section ................ 2.2.1 Fountain Formation (PennsylvanianPermian) ............ 7 2.2.2 Lyons Sandstone Formation (Permian) ................ 7 2.2.3 Lykins Formation (PermianrTriassic) ................. 10 2.2.4 Ralston Creek Formation (Jiurassic) .................. 10 2.2.5 Momson Formation (Jurassic) ...................... 10 2.2.6 Dakota Group (Lower Cretaceous) ................... 10 2.2.7 Benton Shale Formation (Lower/Upper Cretaceous) ....... 11 2.2.8 Niobrara Formation (Upper Cretaceous) ............... 11 2.2.9 Pierre Shale Formation (Upper Cretaceous) ............. 11 2.2.10 Fox Hills Sandstone Formation (Upper Cretaceous) ....... 12 2.2.1 1 Laramie Formation (Upper Cretaceous) ............... 12 2.2.12 Arapahoe Formation (Upper Cretaceous) .............. 12 2.3 Mesozoic and Cenozoic Sedimentary Section .Latest Cretaceousflertiary ................................... 13 2.3.1 Denver Formation (Latest Cretaceous/Paleocene) .......... 13 2.3.2 Dawson Arkose (Latest Cretixeous/Eocene) ............. 12 2.3.3 Green Mountain Conglomeraite (Paleocene) ............. 12 2.4 Quaternary Alluviums ................................. 13 2.4.1 Pediment Alluviums (Quatennary) .................... 13 ROCKY FLATS PLANT REVISXQFk 0 GEOLOGIC CHARACI'ERUATION i DATE. 7131191 TABLE OF CONTENTS - Continued Section Page 2.4.2 Valley Alluviums (Quaternary) ...................... 14 2.4.3 RecentDeposits ................................ 16 3.0 STRUCTURAL GEOLOGY ................................ 17 3.1 Tectonics.. ........................................ 17 3.1.1 Re-Laramide Tectonics ........................... 17 3.1.2 Laramide Tectonics .............................. 19 3.1.3 Post-Larmide Tectonics .......................... 21 3.2 Faulting. .......................................... 21 3.2.1 Golden Fault ................................... 21 3.2.2 Eggleston Fault ................................. 23 3.2.3 Reprocessed Colorado School of Mines Seismic Data ...... 23 4.0 GEOLOGIC MODEL ..................................... 26 4.1 Stratigraphy ........................................ 26 4.1.1 Laramie Formation .............................. 26 4.1.2 Arapahoe Formation ............................. 30 4.1.2.1 Depositional Model ....................... 32 4.1.3 Re-Wisconsin Pediment (Pleistocene) ................. 35 4.1.4 Rocky Flats Alluvium ............................ 40 4.2 Structure .......................................... 40 4.3 Fractures .......................................... 41 4.4 Geomorphologic Effects ............................... 41 4.5 Caliche Mineralization ................................ 42 5.0 HYDROGEOLOGY ...................................... 44 5.1 Introduction ........................................ 44 5.2 Aquifers .......................................... 44 5.3 Uppermost Hydrostratigraphic Unit ........................ 46 6.0 SUMMARY AND CONCLUSIONS ........................... 48 6.1 Reprocessed Colorado School of Mines Seismic Data ........... 48 6.2 Geologic Model ..................................... 48 48 6.2.1 Laramie Formation .............................. ROCKY FLATS PLANT .. REVISION: 0 GEOLOGIC CHARACTERIZAnON 11 DATE: 7/31/91 TABLE OF CONTENTS .Continued Section Page 6.2.2 Arapahoe Formation ............................. 48 6.2.3 he-Wisconsin Pediment ........................... 49 6.2.4 Rocky Flats Alluvium ............................ 49 6.3 Structure .......................................... 50 6.4 Fractures ......................................... 50 6.5 Geomorphologic Effects ............................... 50 6.6 Caliche Mineralization ................................ 51 6.7 Hydrogeology ...................................... 51 7.0 RECOMMENDATIONS ................................... 52 7.1 Drilling Recommendations .............................. 52 7.2 Seismic Recommendations .............................. 52 7.3 Surface Mapping Recommendation ........................ 53 8.0 REFERENCES .......................................... 54 ROCKY FLATS PLANT ... REVISION. 0 GEOLOGIC CHARACTERIZATION 111 DATE 7/31/91 LIST OF APPENDICES Appendix A Rocky Flats Geologic Data Appendix B Map 1: Regional Base Map: Topography, Wells, Cross-Sections, Plant, Roads - Scale: 1" = 500' Map 1A: Base Map Central Plant Area: Topography, Wells, Cross- Sections, Plant, Roads - Scale: 1" = 300' Maps 2 and 2A: Isopach Overlay - Arapahoe Sandstone No. 1: Interpretation 1 - Scales: 1" = 500' and 1" = 300' Maps 3 and 3A: Isopach Overlay - Arapahoe Sandstone No. 1: Interpretation 2 - Scales: 1" = 500' and 1" = 300' Map 4: Channel Trend Overlay - Arapahoe Sandstones 3 and 4 Maps - Scale: 1" = 500' Map 5: Top of Bedrock Elevation Map Overlay Map 6: Alluvium Isopach Map - Scale: 1" = 500' Map 7: Occurrence of Caliche Map Overlay Scale - 1" = 500' Maps 8 and 8A: Water Level Overlay - Scales: 1" = 500' and 1" = 300' Regional West to East Cross-Section Cross-Section A-A' and Site-Specific Cross-Section A-A' Cross-Section B-B' and Site-Specific Cross-Section B-B' Cross-Section C-C' Cross-Section D-D' 0- ROCKY FLATS PLANT REVISION 0 GEOLOGIC CHARA(JTERIZATI0N iv DATE 71331191 LIST OF APPENDICES - Continued Cross-SectionE-E' Cross-section F-F' Cross-section G-G' and Site-Specific Cross-Section G-G' C!ross-Jection H-H' Appendix C Amotated Bibliography on the Geology of the Rocky Flats Plant and Vicinity Appendix D Graphs of Grain Size Analyses Appendix E "Seismic Data Reprocessing," Ebasco Services, Inc. Appendix F "Visual Geologic Logging Protocol for the Geologic Characterization of the Rocky Flats Plant" Fleld Copies of the 1986 and 1987 AS1 Core Descriptions e and Descriptions of Selected 1989 Core Logged by AS1 Appendix G Clomputer Logs of 1986 and 1987 Cores ROCKYFLATSPLANT REVISION: 0 GEOLOGIC CHARAmmON V DATE: 7131191 LIST OF FIGURES Figure Number Title Page 1 Vicinity Map. .............................. 4 2 Generalized Stratigraphic Section, Golden-Momson Area ........................ 8 3 Rocky Flats Plant Site-Specific Stratigraphic Section ................................... 9 4 Erosional Surfaces and Alluvial Deposits East of the Front Range, Colorado ................15 5 Structure Map of the Denver Basin ............... 18 6 Stratigraphic Correlations during the Laranide along the Front Range .................20 7 Location of Faults between Golden and Marshall, Colorado .................................. 22 8 1975-76 CSM Seismic Project Line Location ........25 9 Paleogeography of Western Interior, U.S., during Late Fox Hills Deposition ...................... 27 10 Delta Sedimentation Model Relating Formations to Facies and to Environments of Deposition .......... 28 11 Idealized Deltaic Model for the Laramie, Fox Hills, and Pierre Formations ........................ 29 12 Idealized Fluvial System: Model for the Arapahoe Formation ................................. 33 - ROCKY FLATS PLANT REVISION: 0 GEOLOGIC CIIARACI'ERIZATION vi DATE 7/31/91 LIST OF FIGURES - Continued Figure Number Title Page 13 Sequence of Events: Late Laramie Deposition through Arapahoe Deposition ...................34 14 Generalized Isopach Map of Arapahoe Sandstone No. 1 -- Interpretation 1 .......................... 36 15 Generalized Isopach Map of Arapahoe Sandstone No. 1 .. Interpretation 2 ....................... 37 ? ROCKY FLATS PLANT REVISION: 0 e GEOLOGIC CIIARACERIZATION vii DATE: 7/31/91 LIST OF TABLES Table Number Title Page 1 Arapahoe Sandstones Giving Thickness and Distance between Sandstones ............... 31 2 Presence or Absence of Arapahoe No. 1 Sandstone in Top of Bedrock ............................ 39 3 Comparison of Hydraulic Properties .............. 48 REVISION 0 viii DATE 1/31/91 LIST OF PLATES Plate 1A: Resistivity and Newton Porosity Log with Natural Gamma Ray for B304289 (37-89BR) Plate 1B: Density Porosity Log with Caliper for B304289 (37- 89BR) e ROCKY FLATS PLANT REVISION 0 GEOLOGIC CHARACEIUZATION ix DATE 7131191 ROCKY FLATS PLANT GEOLOGIC CHARACTERIZATION 1.0 INTRODUCTION 1.1 Purpose The goal of the Rocky Flats Plant (RFP) Geologic Characterization effort is to develop a comprehensive geologic framework which can be used to define the direction, rate, and volume of ground water flow; delineate contaminant migration pathways; and characterize potential seismic risks. As a means of furthering these efforts, past geologic processes and events have been evaluated in light of current stratigraphic, structural, geophysical, and hydrogeologic data. This geologic characterization is intended to be used to formulate hydrogeologic models, design and implement ground water monitoring programs, and plan remedial activities. 1.2 Scope of Characterization This multi-faceted investigation involved conducting