_INSPECTION - C1994082 (46) - Laserfiche WebLink

Home Browse Search

Yoast Mine Phase I bond release,pg. 5 The YPM-6-2 channel is downstream of an undisturbed aspen grove and re-enters land disturbed by mining activity. The YPM-6-2 watershed includes a section of a maintenance road. Although the road was excluded from the bond release request by SCC,the slopes adjacent to the road were included. There are rilled road run-out channels in locations between the road and YPM 6-2 that require maintenance. YPM-7 was included in the proposed bond release area,but it had been severely eroded by spring runoff in 2009. Rough grading was also completed along YPM-7, but channel shaping and liner installation had not been completed. For these reasons, the DBMS believes it would be appropriate to exclude a larger, contiguous block of land in the YPM-7 and upper YPM 6-2 watersheds, due to the extent of on-going activity associated with scraper and other equipment access, as well as on-going and future reclamation and stabilization work associated with the maintenance road,the scraper route, lower Channel YPM-7, and Channel YPM 6-2. The YPM-8 watershed upstream of where YPM-8 crosses the temporary maintenance road, on the west side of the road, is not final yet and will be excluded from this bond release. The permittee plans to construct a storm water control runoff structure that directs water to YPM-8. The YPM-8 channel itself, downstream of the road crossing, washed out in 2008. As a result, SCC installed TRM material outside of and parallel to the left channel berm to function as an "ice jam overflow" channel. SCC has also installed 2-3 V-Weirs constructed of willow bundles to direct water outside of the"ice jam" overflow channel and prevent undercutting during periods of intense runoff. Some of the weirs were installed pointed upstream, and others were pointed downstream. These measures are expected to be effective, but given the recurrent erosion problems in the watershed, the DRMS believes it would be prudent to withhold Phase I bond release until the effectiveness of the installations can be observed following runoff season. We measured a representative slope of 30% at the steepest point in the channel. Ms. Brown and Ms. Talvitie walked the entire YPM-10 channel and Mr. Mathew's inspection report will reflect those observations. Measurements were taken along various segments of Channels YPM-16 and YPM-22. The channels were properly constructed and lined in conformance with the approved permit, and appeared stable. YPM-16 is lined with rip-rap and there are indications of a recent repair. We measured a representative slope of 27% in the upper portion of the channel. There is a catch- basin in the lower portion of the channel to slow runoff down. A TRM lined"ice jam overflow" channel had recently been constructed along YPM-22, due to "jump out" and associated gully erosion that occurred this spring during snowmelt. YPM-20 is a short TRM lined channel segment that was recently constructed and appears stable. We also inspected Armand Draw and found it to be stable and well vegetated. We continued at the Electrical Substation Area which has been left as part of the reclamation. The road leading to the substation has been graded,topsoiled, and seeded, but is not included in the bond release area. However;the road area approximately 40 yards past the substation is included in the bond release area. The grading of this area is good and vegetation is new but a little "weedy"with Canadian thistle. A topsoil stockpile remains at the base of the substation road junction. The permittee has included the stockpile in its bond release area, but it is not