Laserfiche WebLink
CNAPTERTHREE <br />Envlrenmental Conse4uences <br />• downstream of the Unocal site, for the period of record from 1975 to 1982 is 31.74 cfs. The 1.6 <br />cfs depletion represents approximately 5 percent of the flow. This reduction in flow is not <br />considered significant enough to adversely affect the riparian habitat or aquatic habitat of <br />Parachute Creek. This analysis of effects is the same for the Agency Preferred Alternative and <br />Proposed Action. <br />3.3.2 Unavoidable Adverse Impacts <br /> <br />The Agency Prefeaed Alternative would result in some unavoidable short-term increased <br />sedimentation during the life of the project. The use of $MPs and reclamation procedwes would <br />min;m;ze these short-term effect and prevent long-term adverse effects to surface water <br />resources. <br />3.4 GROUNDWATER <br />3.4.1 Direct and Indirect Impacts <br />Piceance Site <br />The types of impacts to groundwater resowces would be similaz to those described for the <br />Proposed Action. However, potential adverse impacts would be minimized as discussed below. <br />• The Groundwater and Surface Water Monitoring Plan (Appendix G) requires monitoring of <br />24 groundwater wells to collect additional baseline data before mining begins and to assess <br />potential impacts to groundwater quality during mining operations. Mitigation measwes <br />presented in the plan should help minimize adverse, long-term impacts should any releases to <br />aquifers occw. Quality Asswance/Quality Control (QA/QC) procedwes for field sample <br />collection and laboratory analysis would also be implemented to help enswe collection of <br />representative groundwater quality data. <br />• Implementation of the Well Field Spill Response Plan would help minimize potential adverse <br />impacts to shallow alluvial aquifers should a spill occw due to well field piping failwe. <br />• Well plugging and abandonment procedwes under the Agency Preferred Alternative includes <br />cement plugging of the entire borehole from the base of the intermediate casing string to <br />within 3 feet of ground swface. Compared to the Proposed Action, this would further <br />minimi~r potential impacts to aquifers after the solution mine borehole has been plugged. <br />• Monitoring of physical and chemical parameters of process mining solutions under the <br />Agency Preferred Alternative would help to identify adverse impacts to groundwater and <br />mitigate the problem should physical parazneters exceed established thresholds or chemical <br />pazameters be detected above background levels in monitoring wells. <br />C~ <br />Groundwater 3-5 <br />