Environmental Assessment
Volume C-2
Slurry Pipeline
Project Description
Ambatovy Project
10
January 2006
2
PROJECT DESCRIPTION
The slurry pipeline will connect the outlets of the ore preparation slurry plant at
the mine to the process plant at Toamasina.
The pipeline is designed to handle up to 826 dry metric tonnes per hour of nickel
laterite ore. The design is based on a solids density of 35-40%. The maximum
design flow rate is 1,753 m
3
/h and the pipeline will be used approximately 350
days per year, 24 hours per day for 27 years.
The pipeline will be buried and will be about 195 km long. The material of
construction is steel, with a 550 mm outside diameter and a wall thickness of
9.5 mm. The pipeline will be equipped with cathodic protection. An increase in
wall thickness will be applied at stream or river crossings as an added safety
factor.
Photographs 2-1 to 2-4 show typical pipeline construction and reclamation stages
in pipeline development from previous tropical projects.
2.1
CONSTRUCTION
The pipeline will be buried over its entire length, except at two rivers (KP 68.6
and 70.3) and several smaller streams in deep and narrow valleys. As assessed,
the pipeline would require about 100 watercourse crossings. The majority of
crossings will be buried and will involve excavating across the channel, laying
the pipe, and back-filling the French. Where possible, water will be diverted to
one side of the channel to enable a relatively dry workspace in the opposite side.
Sub-surface directional drilling may be applied at some crossings to avoid stream
disturbances.
The route has been split into two sections – the west and east for construction
logistics and control purposes. The west section is considerably more complex
and expensive than the east section.
The west section will run from the mine site to the west bank of the Rianila River
at kilometre post (KP) 107. Access is a major concern as there are only five
access points to the area in very difficult and mountainous terrain. Right-of-way
ground grading, new access roads and improvements, construction camps, pipe
storage areas and some pipe hauling will be done during the first seasonal ‘dry
window’. The pipe laying activities will take place during the second ‘dry
window’.
