2008-05-01_PERMIT FILE - M2008001

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IV EXHIBIT "G" WATER INFORMATION 6.4.7 A) "Under this Exhibit, the Applicant is required to provide the locations of all permitted wells within 600 feet of the permitted area. Applicant is also required to obtain a damage mitigation agreement from all the well owners, in the event impacts occur due to the proposed operation." Response: The Applicant proposes to install a slurry wall to isolate the mining area and its dewatering operations from the surrounding ground water regime. The applicant will commit to mitigate any damage that might occur due to the installation of the slurry wall. Enclosed with this letter are the wells that are within 600 feet of the permit boundaries of both reservoirs. Please see the INFORMATION BELOW PROVIDED BY RJH CONSULTANTS, INC. THE ENGINEERING COMPANY DOING THE PROJECT ENGINEERING. The primary potential impact of construction of a below ground liner (soil-bentonite cutoff trench) to the groundwater regime is to possibly cause a rise (mounding) up gradient of the liner and a reduction (shadow) in the groundwater elevations down gradient of the liner. The general groundwater gradient at this property is generally north to south and into the Arkansas River. Although during flood stages, the gradient aver part of the property could be from south to north. Based on general groundwater hydraulics and the experience of the design engineer on similar projects, mounding and shadowing is most common near of the center part of liners that are perpendicular to the groundwater flows. Significant changes in groundwater levels are most common when the length of liner perpendicular to the groundwater gradient begins to approach a mile. Two independent liners would be perpendicular to the groundwater gradient at the north end of the site. Each of these liners is less than about 2800 feet long and are separated by about 2500 feet. These liners represent only a minor disruption to the groundwater regime. With very minor mounding in the immediate vicinity of the liner (less than a couple of feet) the groundwater gradient would begin to flow to the east and west and mitigate any significant mounding up gradient. In addition there are no current wells located within 600 feet up gradient of these two liners primarily because the area up gradient of the liner consists of the Highway 50 right-of--way and the railroad right-of--way. The groundwater elevations below the property between the rivo proposed cells would not be impacted by the liner because the groundwater gradient and flow would not be impacted by the two sections of liner that are parallel to the groundwater gradient. Any wells down gradient of the liner would not be influenced by a shadow effect because of the relatively short and discontinuous sections of the liner and because of the presence of a constant source of water from the Arkansas River.