Hydrogeochemistry and simulated solute transport, Piceance Basin, northwestern Colorado

Abstract

Model-calculated drawdown in layer 5 produced by pumping mine near tract C-a at 5 cubic feet per second.. 33. Model-calculated decrease in dissolved-solids concentrations in layer 2 produced by pumping mine near tract C-a at 5 cubic feet per second. ........ 3l+. Model-calculated change in di ssol ved-sol ids concentrations in layer 5 produced by pumping mine near tract C-a at 5 cubic feet per second. ........ 35-37. Graphs showing: 35. Change in model-calculated groundwater discharge and dissolved-solids concentrations in Yellow Creek valley produced by pumping mine near tract C-a at 5 cubic feet per second .

Groundwater chemistry and water-level elevations in bedrock aquifers of the Piceance and Yellow Creek watersheds, Rio Blanco County, Colorado, 2013–16

“…The primary sources of porosity and permeability in the Parachute Creek are fractures in the lean zones as well as vugs and breccias from the dissolution of nahcolite (Coffin and others, 1971). The rich oil-shale zones have high kerogen content and thus are more resistant to fracturing than the lean zones (Weeks and others, 1974;Robson and Saulnier, 1981).…”

“…2). The Mahogany zone is a regionally extensive semiconfining layer (Coffin and others, 1971;Weeks and others, 1974;Robson and Saulnier, 1981). The upper bedrock aquifer system, consisting of water-bearing rocks of the Uinta and Parachute Creek above the Mahogany zone, has unconfined and confined zones.…”

“…During the 1970s and 1980s, studies of groundwater chemistry and aquifer characterization were completed in relation to proposed oil-shale development (Welder and Saulnier, 1978;Robson and Saulnier, 1981;Slawson and others, 1982;Kimball, 1984). These studies were not meant to address the potential effects of oil and natural gas development or nahcolite mining on the bedrock aquifers.…”

Mathematical modeling of solute transport in the subsurface

“…Green River Formation (Eocene): Piceance Basin, Colorado 104 A mathematical model was developed to investigate the possible adverse effects of mine pumping and resaturation of spent shale in an abandoned mine as part of an effort to extract shale oil from sedimentary rocks of the Parachute Creek Member of the Green River Formation. Faults, joints, collapse breccia, and solution cavities are the primary source of permeability in the sand-and marlstone sedimentary rocks.…”

Discharge and water quality of springs in Roan and Parachute Creek basins, northwestern Colorado, 1981-83

“…Because lean oil-shale zones such as the A and B grooves are more fractured than richer oil-shale layers (Robson and Saulnier, 1981), they are more permeable than the richer layers. Therefore, the A and B grooves may be the most significant aquifers in the Parachute Creek Member.…”