CIVIL WORKS GUIDELINES FOR MICRO-HYDROPOWER IN NEPAL
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Box 4.3 Trials of HDPE linings at El Tinte, Peru
The installation of HDPE lining at El Tinte was carried out
in a trapezoidal excavation of 1.2 m width. The material
was laid in a single sheet of 25 m length in a straight
section of the canal as shown in Photograph 4.9. The
thickness of the HDPE sheet was 6 mm. The sheet was
anchored by excavating 150 mm square anchor
trenches parallel to the main canal on each side and
then ramming earth into the anchors, as illustrated in
Figure 4.2 below.
PVC and butyl/ rubber are some of the membrane types
commonly used. Note the differences in this design with
the El Tinte HDPE lining. For example, this design has
gentler side slopes and the lining is covered with sieved
soil, which protects it from being damaged by people
and cattle. This type of plastic lining minimises seepage
loss but requires more labour time for placing it. Laying
the plastic sheet needs careful attention to ensure that it
is not punctured.
Figure 4.2 HDPE Lining at El Tinte, peru.
The labour required for this operation was one
supervisor and one assistant for one day, although a
longer section or one involving curves, would have re-
quired greater time in jointing and cutting the material.
An analysis of costs shows the HDPE-lined canal to be
US$ 10 per m2 for materials delivered to site, which
results in $20 per linear metre of completed canal includ-
ing labour costs. The additional labour cost for a canal
with curves and joints is estimated to be US$ 0.30 per
linear metre.
An estimate of the cost of a concrete canal of the same
dimensions would be around US$ 12 per linear metre.
An alternative buried membrane lining method is pro-
posed in Ref. 5. This is shown below in Figure 4.3. HDPE,
Photo 4.9 HDPE lining at El Tinte, Peru
Figure 4.3 Buried membrane lining porposed in design manual’s for Irritation Projects in Nepal.