Example $4\mathrm{.}11.$ The reservoir for a hydro$-$electric station is $230$ m above the turbine house. The

annual replenishment of the reservoir is $45{10}^{I0}kg.$ What is the energy available at the generating

station bus$-$bars if the loss of head in the hydraulic system is $30$ m and the overall efficiency of the

station is $85\%?$ Also, calculate the diameter of the steel pipes needed if a maximum demand of $45$

$MW$ is to be supplied using two pipes.