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pond on the pit floor. Based on this estimate present in the reclamation plan an <br />adequately sized water storage structure to handle the seepage. Include at a minimum <br />the dimensions, location, vegetation efforts, anticipated water fluctuations, and drainage <br />plans for conveying the seepage to the water storage area. Please note that when you <br />include contributions from precipitation (assuming one to two feet of water in the <br />pond floor over the course of a year) along with the maximum allowable seepage <br />that there would be a moderate amount of exposed water in the pit floor for at <br />least part of the year. Given this, there would be exposed groundwater and <br />precipitation for at least a portion of the year. These would constitute a loss to <br />the hydrologic system. The Applicant may need to provide an augmentation plan <br />for evaporative loss of water. Please comment. <br />2. As discussed during the inspection, the Division is concerned that the water and <br />close by soils into the pit will become saline over time. The sealing of the pond will <br />allow small amounts of water to enter, but not pass back to the groundwater. As <br />seepage and precipitation evaporate the naturally occurring salts will become <br />concentrated and saline condition in the soils and exposed water may result. <br />Please respond to this concern. <br />3. Provide construction details for the compacted clay liner and the process for installation <br />and testing of the compact liner. Essentially we aze looking for the plans, specification, <br />and design criteria of sufficient detail to ensure that the structure is stable and functions <br />as intended.. At a minimum provide the following <br />a. Office of the State Engineer requirements. <br />b. Percent material compaction. <br />c. Liner material composition, percent moisture, percent fines, and testing <br />methods. <br />d. How the liner will be keyed in the bedrock. <br />e. Lift thickness and compaction methods. <br />£ Thickness and width of the finished liner. <br />g. Any geologic investigations on the liner material and substrate bedrock. <br />h. Depth of substrate bedrock scarification. <br />i. Diagrams or drawing of the liner. <br />j. Actions to be taken if the liner does not meet OSE standazds. <br />k. Other information as needed to provide assurance that the liner is stable and <br />will operate as required. <br />1. Cost estimate for installing the liner. <br />Please note that this pit is different from other similarly constructed clay lined <br />sand and gravel pits because the proposed post-mine land use for this site is <br />rangeland not water storage. Concerns about long term maintenance, accounting <br />of evaporation from exposed water, salinity, and meeting the post-mine land use <br />have not necessarily been addressed previously. It is not clear that the same <br />criteria and standards apply. Please clarify what the applicant considers similar <br />or different from a reclamation stand point given the rangeland versus water <br />