In practice, these equivalents can be used to identify the correct difference in
elevation when drawing the platform.
Examples:
a) Every 20 m horizontally with a 1.5% slope, it would be enough to
multiply:
20m x 0.015 = 0.30 m.
b) Every 10 m horizontally with a 2% slope, multiply:
10m x 0.02 = 0.20m
c) Every 20m horizontally with a 2 per thousand slope:
20m x 0.002 = 0.04m.
d) Every 5m with a 4 per thousand slope:
5m x 0.004 = 0.02m
e) Every 2.50m with a 2 per thousand slope
2.50m x 0.002 = 0.005
and so on.
Other characteristics of the platform are determined by the type of soil
(geological characteristics). It is likely that limey, clayey, stony or rocky soil
will be found all along the platform; not all banks will be stable, some will be
damp and will need to be drained. In all cases, the platform must be free of
all organic matter, fill and it must be stable at all times.
Requirements for the platform layout
a) Conduct a survey of the area, from the intake weir to the forebay tank.
b) Verify the plans of the intake weir with the headrace channel, the settling
basin, the conveyance ditch, etc. The levels of each of these must be
consistent, in accordance with the slope established in each case.
c) Have the proper basic instruments and equipment available:
- Mete stick
- Tripod
- Level rods
- 20 to 30m measuring tapes
- Stakes
- Machetes
- 3 to 4 lb sledge hammers
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