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and will affect an additional 0.3 acres. Therefore, the total amount of encroachment will <br />be about 1.5 acres. <br />Drawing Sheet 6 provides conceptual details (but not necessarily construction - <br />ready) and specifications for the ponds and channels located at the historic buffer <br />boundary. The downstream slopes of the ponds are sloped at 3:1 to facilitate re- <br />vegetation and restoration of disturbed terrain to a pseudo - natural appearance. <br />Pond Capacity and Height Restriction <br />The ponds must also be designed to provide the required capacity as terminal <br />ponds during the most critical conditions of mine progression. That required capacity will <br />vary as mining progresses and storm water basins are sequentially changed, sometimes <br />eradicated by mining, and subsequently restored during backfill operations. For <br />example, EMP -021 will initially only accept runoff from the north as EMPO8a is <br />eradicated; followed by flow only from the south as Schist Island is backfilled and Globe <br />Hill is mined; and finally will accept flow from the north, south and east in the final <br />stages of mine life. During those periods, the area tributary to EMP -09 will also change. <br />The size of the three EMP ponds was chosen for the most critical condition for runoff. <br />Typically, the current conditions result in the highest potential for runoff, and the ponds <br />can be built and rebuilt to the volume reflecting current conditions according the <br />sequence shown on Drawing Sheet 5. <br />An additional constraint is the desire for all pond embankments to be non - <br />jurisdictional with respect to dam safety regulation. That means that they are all less <br />than 10 feet high from the center of the dam crest to the pre- existing terrain. Ponds that <br />are excavated below the pre- existing grade do not add to the jurisdictional height. <br />Therefore, the ponds are generally configured to be about 10 feet above grade (at the <br />spillway height) and excavated an additional five feet below grade to provide the <br />optimum depth of 15 feet. <br />Miscellaneous Pond Construction Requirements <br />Three of the four ponds composing EMP -09 will be eradicated by mining in 2016- <br />2017 and their function must be reconstructed by 2018 to receive runoff from the <br />backfilled zones. <br />Client: CC &V Gold Mining Co. <br />Title: Storm Water Management, MLE2 <br />2/2/12 <br />Page 14 <br />