Environmental Assessment
Volume E-6
Tailings Facility
Reclamation and Closure
Ambatovy Project
228
January 2006
Decant weirs (tailings and water basins) will be in filled and incorporated within
the embankment and a closure spillway, suitably armoured to prevent erosion and
will be constructed to redirect flows from the tailings basin into the original
valley downstream. The design will likely include gabions that will permit the
growth of vegetation and establishment of a root mass while also provide
sufficient erosion protection.
Detailed design of tailings basin embankments will include benching and
drainage channels to facilitate runoff and reduce the potential for erosion. The
final embankment raise for the Phase 3 tailings basin will occur during
operations, with the establishment of permanent benching and drainage as well as
vegetation cover. Thus the focus at final closure will be continuing the
revegetation process.
The Phase 3 water basin will be drained and the high-density polyethylene
(HDPE) liner will be removed from the basin. The embankments of the water
basin will be breached and recontoured to restore drainage and mimic the natural
environment, and any remaining disturbed surfaces will be revegetated.
Seepage collection ponds will be infilled and/or stabilized with vegetation and,
with armouring as necessary, and surface runoff will be directed into the original
valley downstream. Return pumps will be removed.
The groundwater recovery system located at the base of each tailings basin will
operate for about 15 years post-closure, when groundwater modelling has
predicted that elevated salt concentrations in groundwater will have subsided.
The recovery system pumps and pipelines will be removed and the boreholes
abandoned.
The reclaim barge will likely be salvaged for re-use at another location or for
parts. Above-grade portions of pipelines, as well as pumping systems, will be
removed at closure. Buried sections of pipelines will be drained and left in place,
as their removal would cause unnecessary disturbance.
It is expected that transportation corridors will remain in-place for a post-closure
period to facilitate site access for monitoring. Unless other users in the region
have become dependent on the access the transportation corridors provide, any
aggregate within the road base may be salvaged for use by others, the road
surfaces will be scarified, and revegetated.
Any stockpiles created during operation of the tailings facility, most likely
topsoil, will either be applied to embankments or the final tailings surfaces. If
