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a iVtzmo to Greet Squire 3 June ~ I 1999 quality assurance and quality control during backfilling. QAlQC costs alone would be on thz order of 500.00 per day for each day that construction is on going. a. The applicant should provide a commitment to install the proposed french drain prior to initial placement of reservoir lining material. Otherwise, sufficient bond would have to be in-place for the Division to install the drain. An appropriate unit cost for drain installation would be 525/linear foot. 5. The applicant proposes to pass ground water around the lined pit in a french drain. For the Division to approve the french drain, the following information must be provided: a) Provide the basis for the assumption that the ground water flow to be bypassed through the drain will be 2 cfs. b) Demonstrate that the drain will provide sufficient capacity based on the diameter and roughness of the pipe and the slope and length of the drain. c) Provide a gradation, plasticity, and durability specification for the pipe bedding and demonstrate that the bedding will not clog the perforations, otherwise wrap the pipe in a geotextile sock. d) There are a number of ponds fed by ground water located directly downgradient of the proposed pit. The owner of these ponds has submitted written comments on the application expressing concern that the ground water feeding the ponds not be interrupted. Demonstrate that the french drain will function such that a ground water shadow below the pit will not adversely impact water supply to the ponds. 6. The northeast corner of the pit is within 120 feet of a sharp bend in the Cache la Poudre River and the pit is within the one percent annual chance flood plain. The applicant should demonstrate that [he reclaimed pit configuration will be stable during a flood, or should provide designs for inlet and outlet works to safely pass the flood through the pit. 7. The proposed bond amount is based on installing pit liner at the point of maximum linear feet of unlined pit under the terms of the mine plan. The u•ay that the current plan is written, the Division does not have adequate regulatory control over the installation of the liner to be assured that the liner will be effective. Under this circumstance, the Division should require sufficient bond to dewater and line the entire pit perimeter. Alternatively, the applicant could provide adequate information and regulatory control to the Division to assure that the liner installed would be functional, then the bonding proposal contained in the application would be acceptable. The information to be provided would be a concise earthwork specification and quality assurance plan for liner installation including a statement that the specification could not be modified without prior consent of the Division. In addition, the applicant must commit to advising the Division of [heir schedule for liner installation so that inspections could be scheduled, and must commit to providing a construction report including all test results and certification from the QA engineer that the approved design plan was executed.