Abstract
M.Sc.
This study focuses on the rehabilitation of borrow pits on linear pipeline projects. In
the past there have been many attempts to rehabilitate borrow pits to an ecological
acceptable manner. Recently legislation has become more stringent regarding mine
closure and rehabilitation. With the introduction of the new Mineral and Petroleum
Development Act (MPRDA 28 of 2002), there has been an increase of awareness
towards the immediate environment.
As this project was a challenge in itself, there were no clear and concise methods in
the Act that provide guidelines for final rehabilitation. Normally borrow pits as used
on road concessions for material sourcing is left as different landforms like before
excavation. The main reason for this is that materials are removed from the pits and
not replaced, resulting in areas that are usually lower than their original ground levels.
Some unwanted screened material will return to these borrow pits but will not
complement what the original level should be. These borrow pits are usually clearly
visible as low lying areas filled with water alongside roads.
The Vaal River Eastern Subsection Augmentation Project (VRESAP) pipeline borrow
pits were unique in the sense that not only material from screening activities were
replaced, but also material excavated from the trench were replaced into the borrow
pits. What makes this study unique is the fact that an opportunity was presented and
clearly stipulated by the standard environmental management plan (SEMP) that
borrow pits had to be filled back to their original ground levels or an acceptable level
agreed on by the landowner.
With this unique project, unique problems arose causing excess material amounting to
327 700 m³, available from the pipeline cavity. External spoil areas had to be
promulgated and managed as part of site. This study through its various elements
addresses some of the main problems encountered on VRESAP by looking at soil
analysis, monitoring regimes, pre and post land use and other mechanisms from
literature studies used on similar projects in the mining industry.
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The study also provides recommendations to the reader for future pipeline
developments as well as conclusions made by the author. The recommendations
made, include ways of rehabilitation planning through trials and errors made on site.
Various conclusions were made that would substantiate this study in perspective to
user-friendly and practical approaches.