GENERAL36924 - Laserfiche WebLink

Home Browse Search

3 ~~ p. 2-17 An illustration would be helpful showing how the project will develop including plan and cross sectional views of the solution cavities. A plan view of the cavities and well fields as they relate to the location and flow patterns of groundwater resources would also be useful. p. 2-24 The mitigation proposed by BLM in section 2.4 does not adequately address the potential for brine movement into the annular space. EPA may require the applicant to modify its plan for mechanical integrity to hold sufficient air pressure at the surface to maintain the liquid/air interface in the annular space below the dissolution surface. EPA now is of the opinion that the surface pressure criteria for :shutting a well in needs to be established such that the liquid/air interface does not extend above the base of the R-6 zone. p. 2-25 It is noted that considerable additional air quality controls may be necessary for the 500,000 TPY alternative. Presumably such measures would be needed by the applicant to assure compliance with the Class II air quality increments under the Clean Air Act. Additional air quality control measures may also become necessary for the proposed action if EPA concluded from its current western states acid deposition investigations that additional sulfur and nitrogen oxide controls; are necessary to assure protection of the air quality related value<,~ of PSD Class I areas. A brief mention of EPA's current acid deposition investigation should be included in the final EIS and deference to the State of Colorado and EPA in implementing possible further controls on sulfur and nitrogen oxides noted accordingly. (Note: The Colorado Department of Health, Air Quality Control Division, received partial delegation from EPA for the PSD program on September 9, 1986.) p. 2-35 The EIS concludes that under the proposed action groundwater quality could not be significantly impacted by direct contamination partly because the area of the base of the groundwater system in contact with the mine represents only one percent of the total area of the aquifer system in the Piceance Basin. It is possible that active dissolution of nacholite is occurring over a smaller portion of the basin rather than, as suggested, the entire basin. If so, then the increased dissolution as a result of this action could produce an impact on groundwater quality different from the areal proportional relationship. p. 3-12 Based upon a report by Wright Water Engineers, the EIS indicates that the hydraulic head difference in the well field area is from 1 to 10 feet. It needs to be established that the well completions showing this difference in head were such that the upper and lower zones were completely isolated when the head differences were measured.