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.. <br />EXHIBIT C <br />STATE ENGINEER GUIDELINES FOR LINING CRITERIA FOR GRAVEL <br />PITS <br />AUGUST 1999 <br />1.01 Desion Standard <br />The intent of the reservoir lining design is to achieve ground water inflow (leakage rate) into the reservoir <br />that is not greater than 0.03 ft /day/ftx (1x 10s cm'/cm=/sec) multiplied by the length of the perimeter wall in <br />feet multiplied by the average vertical depth of the perimeter wall as measured from the ground surface to <br />ttie pit bottom along the toe of the pit side slope, plus 0.0015 ft /day/fly (5x 10'' cm'/cm'/sec) multiplied by_ <br />the area of the bottom of the liner system or natural bedrock bounded by the perimeter wall. Appropriate <br />geotechnicai evaluations and analyses should be performed to indicate that the Design Standard could be <br />achieved with the proposed design to a reasonable probability. It is recommended that the applicant <br />submit design and construction plans for review to the State Engineer. <br />1.02 Construction Standards <br />The applicant must demonstrate that the constructed liner meets the requirements of the design by <br />performing appropriate quality control observations and tests. The applicant shall provide written <br />documentation of the work performed and results of quality wntrol field and laboratory tests. Tests <br />performed shall meet or exceed the standards established by the American Petroleum Institute (API) <br />and/or the American Society of Testing and Materials (ASTM) as applicable. <br />1.03 Performance Standards <br />The Performance Standard shall be three times the Design Standard as described above. The <br />Performance Standard shall be applied to an initial test of competency of the liner, as well as to the <br />ongoing operation of the reservoir. <br />3.1 Initial Liner Test <br />For mined pits: The unregulated ground water inflow to the reservoir will be tested by evacuating the <br />contents of the reservoir and observing the inflow of water over a period of ninety days. The start of the <br />test will be under essentially dry conditions. For unmined pits: The unregulated ground water inflow to the <br />reservoir will be evaluated by constructing a dewatering sump at the lowest portion of the pit and then <br />dewatertng until asteady-state condition is achieved. Once asteady-state condition exists, the amount of <br />the unregulated ground water inflow will be determined. This process will generally require the installation <br />of piezometers to be Located on the inside and outside of the lined pit in the unmined area In order to <br />determine whether asteady-state condition has been achieved. <br />A water balance must be done to demonstrate that the balance of the inflows (e.g., precipitation and <br />ground water) and outflows (e.g., evaporation) equals the change in storage volume by a minimum of a <br />90-day test. Ongoing monitoring of the water balance may also be required as determined by the Division <br />Engineer. The frequency of accounting and monitoring as well as the type and accuracy of the monitoring <br />devices shall be determined after consultation with the Division Engineer. <br />Page 1 of 3 <br />