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<br />Fifteen groundwater monitoring wells are currently in opera- <br />tion within the present and proposed permit area of the Canadian <br />Strip Mine (Exhibit C-2, Appendix C, Vol. 2 of the permit appli- <br />cation). Five of these wells were installed for monitoring Pit 1 <br />and its vicinity. They are completed in the underburden, coal, <br />overburden, and alluvium in order to monitor downgradient effects <br />of the groundwater system before, during, and after mining. <br />Water levels in these wells have been and will continue to be <br />monitored on a monthly basis, with water quality sampling done <br />quarterly (p. 11, Appendix C, Vol. II of the permit application). <br />Nine new monitoring wells were installed within the Pit 2 <br />area. One well was also placed in the compacted spoil area of <br />the original pit in Section 2 to monitor groundwater beneath the <br />reclaimed area. Three of the new wells are completed in the <br />underburden, three in the coal, and three in the overburden. <br />These ten new wells will also be monitored monthly for water <br />levels and quarterly for water quality variables. <br />The water quality parameters to be sampled at every well <br />should be in accordance with those required by the Colorado MLRD <br />(see the stipulation concerning this in Chapter III, Discipline <br />Analysis - Groundwater portion of this TEA). <br />All exploration holes and drilled wells that will not be <br />used as groundwater monitoring stations will be permanently <br />abandoned in accordance with section 4.07.3 of the Colorado <br />Permanent Regulatory Program. Holes drilled in aquifers will be <br />filled to a height of at least 50 feet above the surface of the <br />aquifer (or at least of ground level) with stiff bentonite cement <br />or mud. A 5-foot cement plug will be used to cap the hole. For <br />those groundwater monitoring wells left open in accordance with <br />section 4.05.13 of the Colorado Permanent Regulatory Program, the <br />hole will be cased at a sufficient height above the ground to <br />prevent surface water or other material from entering the well. <br />-41- <br />