Hertzler Stage III Tailings Impoundment
Stillwater Mining Company
Nye, MT
Construction consisted of a zoned earthfill embankment raise of 44 feet in elevation with 2.0-2.5:1 slopes and a 30 foot wide crest. A composite liner system consisting of HDPE geomembrane over a geosynthetic clay liner was installed over all the upstream slopes in order to contain the tailings and process water. The existing tailings distribution and water reclaim pipes were partially removed and relocated and a new section of pipework was installed along the downstream toe of the west embankment. The LAD Storage Pond was expanded and the pond was lined with HDPE geomembrane over geotextile. Principle features of work included:
- Excavation, placement and compaction of 1.9 million cy of material
- Clear and grub of borrow areas
- Removal, storage, and placement of topsoil
- Revegetation of disturbed areas
- Stormwater management
- Construction and maintenance of haul roads and other permanent mine roads
- Expansion of the LAD pond from 60 million gallons to 100 million gallons
- Production and placement of HDPE liner bedding material
- Installation of 100 mil HDPE liner
- Maintenance of existing game fence and construction of new game fence
- Relocation and modification of the 8” HDPE tailings distribution system piping for Stage III expansion including the electrical power distribution for the reclaim pumps
