mag

Malaysia Water Research Journal
The permeability of embankment and foundation materials adopted in the
design based on Angkasa Consulting Services S/B Consulting Engineers are as in
Table 2. Only two main parameters were adopted in this simulation study. Three
seepage measurement weirs are installed to facilitate the measurement of the
seepage water through the dam embankment, only one of the chamber was
used in this studied. The foundation and ground water at the abutments draining
into the dam toe area (which is not significant in the case of Putrajaya main dam
considering the abutment elevation is low.
Material
Table 2. Permeability of embankment and foundation materials
Rock fill 1 x 10-2
Clay core 2 x 10-9
Shoulder Material 1 x 10-8
Sand fill 1 x 10-3
Organic soils and soft clay 1 x 10-8
Alluvial silty sand 1 x 10-7
Naturally occurring residual soils 1 x 10-8
Coefficient of Permeability (m/sec)
Base on suggestion by Angkasa Consulting Services S/B, the maximum
allowable seepage value at each seepage chamber estimated is 0.5 litre/
sec. This seepage measurement chambers comprise of a 900 V-notch weir,
stick gauge (depth indicator) and basin. The objective of the V-notch weirs is
to measure the amount of dam seepage water. Base on Angkasa Consulting
Services S/B, seepage quantity is estimated using the following equation:
where,
Q = 1340 * H2.5 [1]
Q is the flow, litres/sec.
‘H’ is the head of water upstream over the bottom of the V-notch, meter. The
measured seepage rate will be compared against the permissible seepage rate
by International Committee of Large Dam (ICOLD), which is 0.5 l/s (as suggested
by Angkasa Consulting Services S/B) for each seepage chamber set by the dam
designer for dam safety evaluation. The Table shows the seepage V-notch weir
Conversion Table 3 and the dam cross section is shown in Figure 7.
Institut Penyelidikan Hidraulik Kebangsaan Malaysia (NAHRIM)
89
National Hydraulic Institute of Malaysia (NAHRIM)