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<br /> <br />The sediment control system at the mine site consists of two collection <br />ditches and a sediment pond with a capacity of one acre-foot. The sediment <br />control system drains 8.4 acres, of which 2.3 acres are disturbed by the <br />mining operation. The sediment pond is designed to detain the runoff from a <br />10-year, 24-hour storm. The pond is equipped with a dewatering device which <br />allows for 24 hours detention time. The emergency spillway will pass the <br />25-year, 24-hour storm while maintaining one foot of freeboard. All the <br />diversion and interception ditches will pass the 10-year, 24-hour peak flow <br />while maintaining 0.3 feet of freeboard. These structures were found to be in <br />compliance with the requirements of Rule 4.05. <br />There has been no recorded discharge of runoff or snowmelt from the pond <br />during the period 1981-1986. In the event of a discharge from the sediment <br />pond, water would flow through a vegetated Swale 2 miles into Carbon Creek <br />which is a tributary to Ohio Creek. Water flowing down this Swale would move <br />at non-erosive velocities because of dense vegetation and moderately permeable <br />soils. The effects of pond discharge on water quality are not quantifiable at <br />the present time because there has been no discharge from the pond. However, <br />the average computed discharge from the 10-year, 24-hour storm is small at 0.4 <br />cfs in comparison to the lti-year average flow of 89 cfs measured at a USGS <br />gaging station on Ohio Creek. Also, because the discharge point is separated <br />widely from a perennial stream, most, if not all, of the water would <br />infiltrate before it reached Ohio Creek. Therefore, any adverse effects from <br />sediment pond discharge should be negligible. <br />The operation is in compliance with the requirements of this section. <br />VII. Water Rights and Replacement - Rules 2.04.7(3), 2.05.6(3)(ii), <br />2.0 .6 2) c and 4.0 .15 <br />Information on water rights in the area can be found on page 18 and in Exhibit <br />13 of the permit renewal application, <br />The surface water system is designed so that no water rights will be adversely <br />affected by the proposed mining operation, The sediment pond is the only <br />structure that impounds water on the site. The sediment pond will be <br />dewatered within 36 hours following any runoff event thus, any possible down <br />stream users will not be affected. <br />The surface owner at the Nu Mine adit has an absolute decree for up to 0.1 cfs <br />on water leaving the Nu Mine adit. This water right is used for stock <br />watering purposes. The supply of water to this user is dependant upon the <br />water draining from the O.C. P4ine No, 2 into the abandoned Nu Mine workings. <br />As a ma*_ter of practice, the mine pumps ground water into interconnecting <br />~ workings which then allows the water to flow to the Nu Mine adit. Therefore, <br />the proposed operation will not adversely affect the water rights of this user. <br />The only foreseeable adverse effects that the mining operation could have upon <br />water rights holders would be the impoundment of water in the sediment control <br />system or an interference in the discharge of water from the Nu Mine adit. <br />-10- <br />