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<br />Furthermore, the applicant states in the permit application and the Division <br />agrees that the mixing of overburden will mitigate the toxic effects of these <br />materials. D.J. Dollhopf in "Selective Placement of Strip Mine Overburden in <br />Montana" (Chapter 5, Summary Report, 1981) suggests that if the volume of <br />toxic material is less then 15% of the total volume of material to be <br />replaced, dilution of the toxic material can be successful. <br />The applicant states (Volume 2, Tab 6, Pages 6-24 and 6-33) that due to <br />mitigative (avoidance, chemical amendments and dilutional mixing), and <br />topsoiling measures, "...the spoil should be a favorable plan growth medium. <br />The applicant is in compliance with the requirements of this section. <br />V. Ground Water Hydrology - Rules 2.04.5, 2.04.7, 2.05.6(3) and 4.05 <br />Ground water hydrology information can be found in Volumes III and IV, Tab 7, <br />and in Exhibits 7-1 through 7-7. Appendices 7-1, 7-2, 7-3, and 7-7 also <br />contain ground water information. <br />Ground water studies in conjunction with the proposed Seneca II-W site have <br />been concentrated in the Upper Mesaverde Group and alluvial aquifers. <br />Specifically, aquifer characteristics and/or water quality analyses have been <br />performed in the Wolf Creek Coal, Wolf Creek/Wadge Interburden, Wadge Coal, <br />Wadge Coal overburden, and the Hubberson Gulch alluvium. Quantity and quality <br />data have also been collected from ten springs and seeps in and adjacent to <br />the permit area. <br />The proposed Seneca II-W Mine permit area lies on the western flank of the <br />Sage Creek Anticline, a local structure located within the more regional Sand <br />Wash Basin. The Sage Creek Anticline is thought to control local ground water <br />flow, as artesian head increases with distance from the anticlinal axis. <br />The Mancos Shale, underlying the Mesaverde Group, is a relatively impermeable <br />unit which essentially separates the Mesaverde from any underlying, regional <br />aquifers. Important water bearing strata identified along the Sage Creek <br />Anticline within the Mesaverde include the Wolf Creek Coal, Wadge Coal, and <br />the Wadge Coal overburden. Recharge to these and other aquifers in the area <br />is a function of infiltration of snowmelt and rainfall at outcrops along the <br />anticline. Water table conditions prevail near the aquifer outcrops, while <br />confined conditions exist further downdip. <br />Each of the identified aquifer zones are hydraulically discontinuous with the <br />units above and below. Therefore, each aquifer will be discussed as a <br />separate entity. <br />-16- <br />