140 CIVIL WORKS GUIDELINES FOR MICRO-HYDROPOWER IN NEPAL
Figure 10.3
10.6 PVC pipes
PVC pipes are frequently used by Intermediate Technology for
penstocks in its micro-hydro programme in the northern Andes.
One of the first schemes to benefit was Chalan. This project has
a capacity of 25 kW, and a head of 96 metres. The penstock
diameter is 200 mm. Connection of pipe lengths was through
glued spigot and socket joints. On commissioning, it was found
that pinhole leaks appeared in the joints, a problem that was
addressed through the application of additional resin. The
whole length of the penstock was buried for protection from
sunlight, animals and other potential sources of damage.
10.7 Anchor block design
The stability calculations for anchor block design are time
consuming. A spreadsheet program for the stability analyses
has been written by John Bywater to speed up the process. To
date there is no manual to accompany the program, nor
evidence that it has been verified. However, the program was
used to verify the guidelines given in Section 7.4.4. for sizing
anchor blocks for small schemes.
Photo 10.7 Load test of steel support pier (side elevation)
Photo 10.8 Load test of steel support pier (front elevation)