the vertical drainage system, If the above-mentioned principles and the tech-
nical resources of the maintenance service are taken into consideration in
drawing up the pumping regimen it can be used as the basis for drawing up
an operating schedule of the system of drain wells.

The following is the result of calculations for pumping regimens (Fig. 1)
applied to the easy lithological and hydrogeological conditions of Kagan
district in Bukhara region where the surface fine soil does not exceed 8—12
mefres and the seepage ratio is equal to 0.12—0.5 metres per day. The
system of 92 drainage wells over an area of 10,200 hectares operates 230
days a year pumping 5,074 cu.m of water per heciare and maintaining the
ground wafer table at 1.8 to 3.3 metres from the surface depending on the
season. In May and November the system is swiiched off and during the
growing pericd there is also a break in the operation of the drainage.

Fig. 2 illustrates a schedule for the operation of drainage wells in more
difficult soil and melioration conditions with the fine topsoil reaching down
to a depth of 25—30 metres and a seepage ratio of up to 0.1 metre per day.
In this case the system of 72 drainage wells operates during 288 days remo-
ving 7,267 cu.m of waler per hectare and maintaining the ground water table
а! 1.05—3.34 metres from the surface. The number of wells operating simulta-
neously to mainiain the given schedule ranges from 32 to 65. In June and
October the system is switched off completely. In both cases the breaks in
operation are used for running repairs and major overhaul of the equipment
and installations.