2012-10-19_INSPECTION - C1996084

Home Browse Search

October 19, 2012 C- 1996- 084 /Lorencito Canyon Mine LDS HYDROLOGIC BALANCE - Rule 4.05: Drainage Control 4.05.1, 4.05.2, 4.05.3; Siltation Structures 4.05.5, 4.05.6; Discharge Structures 4.05.7, 4.05.10; Diversions 4.05.4; Effluent Limits 4.05.2; Ground Water Monitoring 4.05.13; Surface Water Monitoring 4.05.13; Drainage — Acid and Toxic Materials 4.05.8; Impoundments 4.05.6, 4.05.9; Stream Buffer Zones 4.05.18. Pond 9/9b was dry. The embankment, primary discharge and spillway were all sound. According to Ron the pond has not discharged for at least 3 years. An erosional gully had formed on the left side (west) of the spillway, which will need to be repaired (see photos 1 -3). The silt fence, protecting the undisturbed area from runoff from the road should also be restored. Armoring in the ditch draining the slope above pond 9/9b needs some repair (see photos 1 & 4), the ditch could be widened to reduce the steepness of the sides. The steep north facing slope above pond 9/9b had fairly sparse vegetation following several dry years, making the slope vulnerable to erosion (see photos 5 -6). Some gully repair is needed here, as at several locations around the site — limited reseeding may be performed as part of this gully repair process without resetting the clock with respect to vegetative success criteria for bond release. Several years previously a diversion had been created higher in the watershed to reduce the flow to pond 9/9b, and send more water to pond 9a (see photo 7). Pond 9a was holding a little water, but was well below the discharge level, (see photo 8). The armoring in the drainage on the eastern side of fill 9a had been eroded in places and will need to be restored to limit further damage (see photo 9). On the west side of fill 9a the channel had been altered to improve the flow during large rain events and reduce the potential for ditch breaches, (see photo 10). The spillway from pond 9a was sound. Pond 7 was holding sufficient water to host a flock of ducks, but was well below the discharge level, (see photo 11). Above the west side of pond 7, near the bottom of fill 7, was a gully which will need to be monitored, (see photo 12); if access to this gully were easier, repair would be encouraged, but it is not clear that it could be accomplished without creating a larger disturbance. Since the gullies in this area appear to contain growing vegetation, there is a chance that erosion will be controlled without further intervention. There are several rills and one more significant gully on the slopes where fill 6 would have been (see photo 13). These areas should be repaired, possibly from the road above. Long distance hydro - mulching could be a good option to avoid creating further disturbance. Erosion on the spillway of pond 6 needs to be filled, possibly with pond sediment, and protected with a line of straw bales. Pond 6 was holding a little water, but well below the discharge level. Sediment traps above pond 6 were effective, but require some straw bale maintenance. • The topsoil borrow area SAE requires some straw bale maintenance. • The outlet of the culverts to the north of the reference area were partially caved in and need repair, (see photo 14) • Pond 5 was muddy. All culverts under the road were sound. The drainage could be a candidate for bond release, although a small SAE may be needed at the top of the drainage. • Pond 8 was sound (see photo 15). Most of the water that would drain to it was held in smaller gas well ponds higher up the drainage. The first culvert under the road to pond 8 needs to be cleaned. The second and third culverts were fine. These culverts, and their owners, should be identified on the map(s) generated as part of the permit renewal process. There was a very steep ditch above the road to pond 8 Number of Partial Inspection this Fiscal Year: 3 Number of Complete Inspections this Fiscal Year: 2 Page 3 of 11