3. Intermediate station arrangement. Fig. 11.18 shows the economic site of the power house at
an intermediate section of the entire power conduit. The specific characteristic of this arrangement is
long headrace tunnel and a long tailrace tunnel. Upstream and downstream surge tanks are necessary as
shown in figure to deal with the pressure oscillations in both headrace and tailrace. If the prime mover is
impulse type, there is no interference between tailrace and headrace level and, therefore, the dimensions