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collection ditches will have to be installed in order to gather and direct run -off to the sediment sumps. <br />The designs for these ditches are found below in this section as well. <br />The main sources of potential sediment on site are fines from the cutting of marble blocks from <br />underground. Fines have been placed on the roads, some slopes and a the Mud Drying Dump, as shown <br />on Map C -2. The existing marble dump areas can also be seen on Map C -2, which contain some <br />combination of marble fines or marble blocks. These areas basically lie entirely within the disturbed area <br />line on the map. Future block storage may extend beyond this current boundary. The sediment sumps <br />proposed in this plan will trap and contain all of the water from a 10 -year event on site. Each sump will <br />provide sufficient detention time to ensure that sediment drops out of the contained water within 48 <br />hours due to the granular nature of the material at the bottom of the sumps. CSQ's experience on site has <br />been that most water contained within a sump infiltrates into the underlying soil and rock. However, <br />each sediment sump is designed with a principal spillway pipe and a water discharge emergency <br />spillway to allow for water to leave the sump once sediment has dropped out or to allow discharge of <br />waters up to the 100 year event. Although no discharges are expected for any event up to 10 year <br />frequency, any discharges will be regulated under a Colorado Department of Public Health and <br />Environment (CDPHE) discharge permit. <br />The mine roads have been used in the past to store fine waste from the marble cutting. All mine road <br />runoff will be collected by the ditches and sumps, as shown on Map C -2. The roads will be graded to the <br />inside ditches at a grade no milder than 1%. <br />Yule Quarry April 2012 21 <br />