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<br />were subsequently determined that ground water was leaking into the pit at a rate in excess of <br />3x0.03 ft'/day/ft`', the operator would be faced with the following three options: <br />• Improve the seal in the pit to meet the State Engineer's leakage criteria. <br />• Change the post mining land use and provide water to augment for ground water leaking <br />into the pit that is lost to evaporation. <br />• Backfill the pit so that water is no longer exposed to the atmosphere. <br />In the event the Division were to assume responsibility for reclamation of the pit through bond <br />forfeiture, we may be confronted with the same situation and the same three options. Of these <br />options, water augmentation in the South Platte River Basin and backfilling of the pit with inert <br />fill would be the most costly. Also, neither of these options would result in reclamation to the <br />developed water resources use. This leaves the option of assuring [hat leakage into the pit is less <br />than 3x0.03 ft'lday/ft' through reinstallation or repair of the slurry wall. <br />The Division proposes that two permitting options are suitable for assuring that the post mining <br />land use of developed water resources will be established at the Ft. Lupton Sand and Gravel Mine <br />site through the installation of slurry walls. These options are described below. <br />Reeulated Construction Option <br />The applicant may provide design drawings (current submittal is adequate) and specifications for <br />the installation of the slurry wall along with a quality assurance/quality control plan. These <br />documents would be binding under the terms of the permit, and the Division would require a <br />statement that the plans and specifications, once approved, could not be altered without consent <br />by the Division. The operator would be required to advise the Division of the schedule for <br />construction ofthe slurry wall so that inspections could be scheduled at appropriate times during <br />installation. The operator would be further required to provide a construction report detailing the <br />installation of the slurry wall, describing any problems that occurred, and listing [he results of <br />testing that was conducted under the approved quality assurance/quality control plan. A <br />certification would be required to accompany the construction report with a statement from the <br />quality assurance engineer that the slurry wall was constructed in accordance with the approved <br />plans and specifications. <br />With the level of regulatory control over the installation of the slurry wall described above, the <br />Division would gain a high degree of assurance that the design standard leakage criterion of 0.03 <br />ft'/day/ftZ would be met. With this level of assurance, contingency bonding for repair or <br />replacement of 20 percent of the total. linear feet of slurry wall would be acceptable. The number <br />of linear feet of slurry wall and the slurry wall installation costs for the site are discussed below. <br />A table summarizing a typical specification and quality control plan is attached. <br />Performance Bondine Option <br />In this option, the operators would be left to their own devises in the design, installation, and <br />testing of the slurry wall, but would be required to demonstrate that the sltitry wall limits leakage <br />into the pit in accordance with the State Engineer's criteria. In this case, the Division would not <br />have regulatory control over construction of the slurry wall, and should bond for the cost to <br />install a complete replacement slurry wall. The performance bonding option considers the worst <br />