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3. The Division had granted an exemption from the use of sediment ponds for <br />drainage from underground mine workings since no mixing with surface <br />drainage would occur and due to the fact that sediment ponds were not <br />necessary for the drainage to meet effluent limitations of Rule 4.0.2 and <br />applicable State and Federal water quality standards for receiving streams. <br />However, increasing iron concentra[ions in the mine water discharge forced <br />the operator to use treatment ponds to reduce the iron to compliance limits <br />before discharge into North Thompson Creek. These discharges are from the <br />No. 1 Mine portal and airshaft area and the No. 3 Mine portal area. The <br />discharge water from the No. 1 Mine portal and airshafr area is diverted to a <br />series of treatment ponds where iron and sediment are allowed to settle out. <br />Because sediment is removed in the treatment ponds, additional residence <br />time in the sediment ponds is not required. Therefore, water from the <br />treatment ponds bypasses the sediment ponds and is directly discharged to the <br />stream. The location of the portal area is shown on Drawing D-2-5 of the <br />permit application. Prior to the middle of 1995, the mine water from the <br />Mine No. 3 portal had no history of iron or sediment problems, and was, <br />therefore, discharged directly to the stream without treatment. However, the <br />iron concentration in the Mine No. 3 discharge water began to increase <br />beyond compliance limits. Therefore, this discharge is also passed through <br />the treatment ponds in order to meet compliance limits. <br />B. Sedimentation Ponds <br />1. Alternative design criteria and specifications have been approved for use in <br />sediment pond design and/or construction. This decision is based on a <br />thorough analytical demonstration by a qualified professional engineer that the <br />resulting sediment pond will be as environmentally sound and structurally <br />stable taking into consideration physical, climatological and other <br />characteristics of the site (4.05.6(11)). The pond referenced in this section is <br />Pond P-9. Although ponds are not required for sediment control anymore. <br />Pond P-9 was not reclaimed. This pond serves a dual purpose as a sediment <br />pond for disturbed area runoff and, at times, a treatment pond for the Mine <br />No. 1 discharge water. <br />C. Impoundments <br />1. The applicant has proposed the use of alternative design criteria and <br />specifications for impoundment design and construction. The Division <br />approved of these alternative criteria and specifications based on a thorough <br />analytical demonstration by a qualified, registered professional engineer. <br />This demonstration takes into consideration physical, climatological and other <br />site characteristics, and shows that the resultant structure will be as <br />environmentally sound and structurally stable as those resulting from <br />compliance with the requirements of Rule 4.05.9 (4.04.9(12)). The ponds <br />15 <br />