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STATE ENGINEER GUIDELINES FOR <br />LINING CRITERIA FOR GRAVEL PITS <br />AUGUST 1999 <br />1.0 Design Standard <br />The intent of the reservoir lining design is to achieve ground water inflow (leakage rate) into <br />the reservoir that is not greater than 0.03 ft3 /day /ft2 (1x 10'5 cm3 /cm2 /sec) multiplied by the <br />length of the perimeter wall in feet multiplied by the average vertical depth of the perimeter <br />wall as measured from the ground surface to the pit bottom along the toe of the pit side slope, <br />plus 0.0015 ft3 /day /ft2 (5x 10-7 cm3 /cm2 /sec) multiplied by the area of the bottom of the liner <br />system or natural bedrock bounded by the perimeter wall. Appropriate geotechnical <br />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 <br />applicant submit design and construction plans for review to the State Engineer, <br />2.0 Construction Standards <br />The applicant must demonstrate that the constructed liner meets the requirements of the <br />design by performing appropriate quality control observations and tests. The applicant shall <br />provide written documentation of the work performed and results of quality control field and <br />laboratory tests. Tests performed shall meet or exceed the standards established by the <br />American Petroleum Institute (API) and /or the American Society of Testing and Materials <br />(ASTM) as applicable. <br />3.0 Performance Standards <br />The Performance Standard shall be three times the Design Standard as described above. <br />The Performance Standard shall be applied to an initial test of competency of the liner, as <br />well as to the 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 <br />evacuating the contents of the reservoir and observing the inflow of <br />water over a period of ninety days. The start of the test will be under <br />essentially dry conditions. <br />For unmined pits: The unregulated ground water inflow to the reservoir will be evaluated <br />by constructing a dewatering sump at the lowest portion of the pit and <br />then dewatering until a steady -state condition is achieved. Once a <br />steady -state condition exists, the amount of the unregulated ground <br />water inflow will be determined. This process will generally require <br />the installation of piezometers to be located on the inside and outside <br />of the lined pit in the unmined area in order to determine whether a <br />steady -state condition has been achieved. <br />Lining Criteria for Gravel Pits.doc 1 08/16/99 <br />