PERMFILE49182 - Laserfiche WebLink

Home Browse Search

Tab 20, Backfilling and I;r ading). Replaced topsoil material should exhibit infiltration • rates comparable [o or exceeding that of premining soils. Reclamation techniques used in the topsoiled areas (select disking and deep ripping), in combination with reestablished uetershed topographies will minimize excessive rates and volumes of runoff. Stream Buffer Zones. l,nnand Drziw has been characterized in Tab 7 as principally ezhibi ling ephemeral flow excepting a two month period in the spring where intermittent flow may occur as a result of benlc storage from snowmelt. Scotchman's Gulch, which has not been formally monitored, eppea rs to exhibit similar flow behavior (based on visual ohs ervations and the fact chat channel flow ceases in the summer). It is believed that no biological communities as defined in 4.05.78(3) of the Colorado regulations are present in either drainage; houeve r, specific: biologic surveys have not been performed. Thus, a section on stream buffer zones in and adjacent to the Yoast mining area is included in Tab 16, Protection of the Hydrologic Balance. The haul road exiting the north end of the Yoast Mine and a utility road will come within 100 feet of Annand Draw at three locations in Section 8 and at one location along Scotchman's Gulch in Section 32 (see Exhibit 13-2, Sheets 1 of 2 and 2 of 2). The disturbances include three culvert crossings of Annand Draw associated with the haul road and utility road crossings and one culvert crossing of Scotchman's Gulch associated with the haul road crossing. ~~ The impacts of these crossings to the hydrologic balance of Annanld Draw and Scotchman's Gulch will be negligible. The above-referenced culverts and the associated road ditches are all designed to convey the 10-year, 24-hour runoff. The cons[ Auction used only native fill materials. Riprapping of drainage ditch downdrains and immediately up- and downstream of culverts is proposed in the facilities chapter, Tab 13. This will help minimize erosion and the entrainment of any additional suspended sediment. The disturbance areas associated with the culverts and ditches wilt be ~ seeded with mixes that promote the rapid reestablishment of vegetation. This will also minimize erosion and any potential additions of sediment to the streamf Low. No riparian vegletation has been mapped at the four disturbance areas. The culvert locations on Annand Draw have been mapped as having mesic drainage vegetation and the location on Scotchman's Gulch is mapped as alkali meadow vegetation. The seed mixes proposed to be used for revegetating these drainage disturbance areas contain the native species identified in the vegetation surveys of these areas. i I u 4