Laserfiche WebLink
The oil separator will be cleaned out as required. The oil separator will be fitted with two <br />• manholes for easy access to the oil trapping baffle. A cleanout pipe is also provided for cleaning <br />the 6 -inch line between the oil separator and the stormwater retention pond. <br />Stormwater Retention Pond <br />The stormwater retention pond is the last structure in the series of stormwater management facilities <br />proposed for the train loadout facility. All stormwater runoff from the paved containment area and <br />facility washwater passing through the sediment trap and oil separator will drain to the stormwater <br />retention pond. Stormwater runoff from the portion of the paved containment area downgradient of <br />the sediment trap will also drain to the stormwater retention pond. The stormwater retention pond <br />layout and design details are shown on Drawings 1 and 3 in Appendix A. <br />Tie stormwater retention pond is sized to contain the volume of washwater that will accumulate <br />from a week of average washdown activity (approximately 2500 cubic feet) and the stormwater <br />runoff from the paved containment area resulting from a 25 -year, 24 -hour storm event <br />•= ` <br />(approximately weekly washdown water volume was estimated from the <br />Y 3000 cubic feet). ) The wee Y <br />washwater flowmeter records provided by West Elk Mine. The volume of stormwater runoff was <br />estimated using methodology presented in Soil Conservation Service Technical Release 55, <br />Urban Hydrology for Small Watersheds, 1986. (The hydrology and sizing calculations are <br />included in Appendices B and C, respectively.) <br />As shown on Drawings 1 and 3, the stormwater retention pond is designed with two discharge <br />pipes. A gated pipe will be located on the south wall near the bottom of the retention pond. The <br />pipe will provide controlled releases from the pond as planned by West Elk personnel. An <br />emergency spillway pipe will be located on the south wall at the top of the retention pond. The <br />emergency spillway pipe will provide controlled releases from the pond during storm events larger <br />than the 25 -year, 24 -hour storm event. Discharges from both pipes will gravity -flow to an existing <br />Colorado Department of Transportation stormwater inlet located southwest of the train loadout <br />facility along Highway 133. <br />West Elk Mine Train Loadout Environmental Improvements Shepherd Miller, Inc <br />p:U i -407Veport\report.doc 5 July 1997 (Revised April 1998) <br />