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| Unreinforced polypropylene (0.75mm) |
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Pages in this section include:
| Description |
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Refer Unreinforced Polypropylene (1mm).
| Experience |
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Common polypropylene applications include floating covers, landfill
liners and caps, tank liners and sewage processing ponds. No literature
reporting its effectiveness from this experience has been found,
but the manufacturer estimates a useful life of 15 years (for areas
south of 30° latitude).
Unreinforced polypropylene (PPU) (0.75mm) was trialed in 200m of
the Finley Main Channel by Murray Irrigation Limited in July 2002.
| Site
preparation |
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Subgrade preparation required:
- Channel reprofiling to achieve consistent batter slopes
and minimal protrusions.
- Silt and clod removal.
| Installation |
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Method of installation
Installation occurred during July 2002. Approximately
half a day was required for installation.
The PPU was prefabricated and came in 50m lengths
approximately 20m wide. The material was laid in
the channel and then folded out like a tarpaulin.
A crew of 10 was required to unfold and manoeuvre
the material into place. Two additional crew members
were required to weld sections together.
The liner was anchored in trenches along the channel
bank and the end treatment utilised geosynthetic
clay lining (GCL).
Figure 1 Laying the PPU
Figure 2 Channel section near completion
Specialised equipment
Material spool and joining equipment.
Installation Issues
Despite a large labour requirement, the installation was
straightforward.
Correct set-out of the material was required to ensure that the
joins matched.
Weather
considerations
Wind conditions during installation were ideal. Windy conditions
could cause installation problems, particularly with such large
sections of material.
| Durability |
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The manufacturer estimates a useful life of 15 years
(for areas south of 30° latitude).
| Seepage
reduction |
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The baseline seepage
rate at the PPU Finley
Main Channel site was
7.0L/m2/day. A pondage
test in 2003 identified
a seepage reduction of
71% (to 2.0L/m2/day).
| Cost |
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A breakdown of the costs is presented in the table below. The total
lining cost of $43,673 (2002), or $11.93/m2, is based on a supplied
surface area of 3,800m2.
Table 1 Breakdown of costs for PPU (1.0mm)
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Item
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Cost ($)
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Cost ($/m2)1
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Earth works (excavator, loader, etc.)
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$4,223 |
$1.13 |
| Materials |
$19,000 |
$5.07 |
| Delivery |
$1,800 |
$0.48 |
| Installation |
$12,508 |
$3.34 |
| MIL staff wages, on-costs, etc. |
$2,080 |
$0.56 |
| Fencing |
$5,000 |
$25.00/m |
| Misc. |
$62 |
$0.02 |
| TOTAL |
$44,673 |
$11.93 |
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1. Cost per square metre based on 3,800m2 of material supplied.
2. Cost per metre of fencing based on 200m section of channel.
Cost for materials and installation are indicative of a commercial
application to a longer section of channel. Other costs would
be expected to reduce marginally as economies of scale in
earth works, delivery, utilisation of staff, and fencing
are achieved. These costs are exclusive of GST.
| Advantages
and disadvantages |
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Advantages
- Under favourable weather conditions, the PPU was
installed in half a day. This highlights the benefits
of the technique, in that large sections can be done
quickly, but the labour requirements are high.
Disadvantages
- Windy conditions would cause significant installation
problems, particularly with large sections of material.
- The
use of prefabricated material highlighted the need
to accurately estimate the channel dimensions prior to
manufacture. In this case, the width of the channel
was
over-estimated, which meant that there was a considerable
amount of material left over.
- Exposed installations
require fencing to prevent risk of damage by animals.
| Related
pages |
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Flexible membrane lining
techniques
Flexible
membrane materials
Covered liners
High-density
polyethylene (0.75mm)
Geosynthetic
clay liners
Exposed liners
High-density
polyethylene (2mm exposed)
High-density
polyethylene (1.5mm exposed)
Linear
low-density PE and very low-density PE
(1.5mm)
DamSeal
Unreinforced
polypropylene (1mm)
Reinforced
polypropylene (1.1mm)
Butyl
rubber
Asphalt |
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