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~~ ~~ <br />The heap leach system will use drip emitters to supply the sodium cyanide <br />solution to the ore. This system applies the solution directly to the <br />ore surface. Solution losses due to wind are extremely minimal. Any <br />solution blown from the heap's surface would probably be quickly <br />evaporated, with the cyanide degraded due to ultraviolet radiation. <br />As is normal for ail areas where sodium cyanide solution is used, the <br />ponds and heap are underlain by a dual impermeable liner system. The <br />lowest, or secondary, liner will be constructed of 12 inches. of soils <br />amended with bentonite and compacted to 10-6 cm/second (1 molecule of <br />water wil] travel through the ]finer at a rate of 0.0007 inches per hour) <br />every second under saturated conditions. This is considered to be an <br />impermeable boundary. Immediately overlying the clay liner will be <br />twelve inches of coarse sand. This is the leak detection system, also <br />referred to as the secondary recovery system. This system its designed <br />and will function to contain any chemical solutions which may leak from <br />the overlying primary liner. Any solution which enters the leak <br />detection system will flow downslope to a sump, or low lying area, which <br />will have a number of wells completed in it. The entire leak detection <br />system, including the sump, is under - and over-lain by the secondary and <br />primary liners. These wells will be monitored on a regular basis during <br />the life of the mine to detect whether cyanide solution is present. If <br />solution is found within the sump area, appropriate responses are <br />initiated depending upon the rate of leakage. The criteria and <br />corresponding actions have been defined in the permit as foVlows: <br />Heap Leach Pads <br />0 to 20 gallons/acre/day/(gpad) <br />20 to 100 gpad <br />100 to 300 gpad <br />300 to 500 gpad <br />500 gpad <br />Report to MLRD. <br />Report to MLRD, addit~~onal <br />monitoring implemented, pump <br />from sump as required. <br />Locate area of leakage, change <br />pad loading/spraying to reduce <br />leakage, pump from sump as required. <br />leakage area shutdown until <br />leaks repaired <br />leakage area shutdown, <br />replace primary liner. <br />Pregnant and Barren Ponds <br />0 to 20 gpad <br />20 to 130 gpad <br />Report to MLRD. <br />Report to MLRD, additional <br />monitoring required, pump from <br />sump as required. <br />-4- <br />