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Executfue Summary • Preferred Alternative in response to public and agency comments on the Draft EIS. These modifications are described in Chapter 2.0 of this Final EIS. ENVIRONMENTAL CONSEQUENCES The following is a summary of potential environmental effects resulting from the proposed Yankee Gulch Project discussed by resource azea. Proposed Action, Accelerated Development and Agency Prefemed Alternatives Geology. For both the Proposed Action and the Accelerated Development Alternative, surface subsidence would range from 1 to 3 ft or less, with no visible surface cracks, and would occur slowly over geologic time. Under the Agency Preferred Alternative, impacts to geological resources would be less than those impacts associated with the Proposed Action. Through monitoring techniques identified in the Subsidence Monitoring Plan, subsurface movement would be detected, and mitigative actions would be implemented. The mineability of oil shale in the oil-rich Mahogany Zone and of dawsonite reserves throughout the oil shale would not be affected under any of the three action alternatives. Potential impacts to mineability of oil shale in the Saline Zone cannot be estimated at this time because future oil shale extraction technologies are unknown. Soils. The Proposed Action would disturb 1,562.5 acres of soils, including 128.5 acres occupied by permanent facilities, 951 acres disturbed during construction (short term), and 483 acres in mine panels (5-year increments). Much of the impact would occur to soils considered fragile because of shallow depths, susceptibility to erosion, or steep slopes. Some soil loss due to erosion, an interruption of natural soil development, and loss of productivity would occur; however, impacts would be minimized by erosion control and reclamation. If erosion control or reclamation were unsuccessful, there would be long-term adverse effects to soils. The impacts of the Accelerated Development Alternative would be similar and would involve a slightly larger azea of disturbance and a shorter period of mining operations. The azea of impact would be similaz to the Proposed Action for the Agency Preferred Alternative. The amount of soil lost through erosion would be lessened through the incorporation of soil retention techniques identified in the Reclamation Plan. Seed mixtures aze included in the Reclamation Plan that would facilitate soil stabilization and re-establishment of the plant community. Surface Water and Surface Water Drainages. No significant long-term impacts to surface water resources aze anticipated under any of the three action alternatives. Short-term increases of sedimentation would result from construction activities at all three project sites, which would be minimi~Pd with effective implementation of Best Management Practices (BMPs) and reclamation efforts. The Agency Preferred Alternative includes detailed descriptions of erosion control methods, spill response planning, and surface water monitoring. The only discharges to surface water dra' es, other thaw stormwater runoff, would be of hydrostatic test water from the natural gas pipeline and project pipelines. The water would be tested prior to dischazge to ensure that no water quality violations would occur. Approximately 1,158 acre-feet per year (1.6 • cubic feet per second [cfs]) of water from alluvial groundwater wells and the Colorado River would be consumed by production and processing activities under the Proposed Action and the ES-3