Program Implementation consists of
three phases:
- Selection of
Villages
- Drilling
Operations
- Installation of
New Pumps and Repair of Old Pumps
Selection of the Villages
The selected villages have a
population ranging from 50 to 450 people. Highest
priority is given to those villages where no drilled or
hand-dug wells exist and people collect water from
unprotected, rudimentary dug open holes, generally
located in river beds and depressions. Water from these
rudimentary holes becomes green-yellowish during the dry
months; frogs, snakes and insects abound in this dirty
water. Buffaloes and other animals drop their waste
around them.
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During the monsoon the
holes are filled by run-off water carrying mud
and animal dung. The mud is removed at the start
of the dry season . The water pit is redug and
used again , generally from December to June ,
the start of the rainy season, as shown on the
left. The selection of the villages is done with
the participation of a junior engineer of the
local rural development office who acts as
interpreter and organises the first village
meeting. The village water survey is carried out
by the author; borehole site selection is done
with people’s participation and approval. |
Drilling operations
Maharashtra State is covered by nearly 90% of Mesozoic and early Tertiary volcanic
rocks, characterised by a thick sequence of lava flows. Aquifers are generally shallow,
represented by weathered and fractured basalt located mainly in depressions, river sides,
flat areas. Deeper aquifers may also occur. They are, in most cases, represented by inter-
lava flow materials, exceptionally by granular rock types. Some prospects to find
groundwater is also along fault lines and dykes. As most boreholes struck water within the
first 100 feet, it was found more appropriate to drill, for the same village, two boreholes of
100 feet each rather than to insist on going deeper in a dry hole and reach 200 feet as is
usually done by other organizations; such a depth may be justified only in areas where
previous drillings have proved the existence of a deep aquifer.
The average yield of boreholes drilled by the project in volcanic rocks of Maharashtra is in
the order of 1500 litres per hour; in a few cases borehole yield reached 10,000 litres or
more per hour. Drilling is carried out by a contractor using a down-the-hole hammer
drilling. Casing is inserted only in the soft and weathered upper section of the rock
sequence. The average rate of success has been around 90% . The high rate of success is
due to:
a very accurate borehole site survey;
a constant supervision of the drilling operations and flow measurements;
the use of slotted casing, whenever appropriate; and
the installation of the bucket pump in a number of low-yielding boreholes.
Hand Pump Installation
Two types of pumps are installed by the program: the Mark II hand-pump and
the bucket pump described ahead . The Mark II pump is installed in boreholes having
good yield (generally not less than 300 litres per hour) and in villages with at least 100
people. The bucket pump is designed for villages with less than 100 people or for villages
located in remote areas inaccessible during the wet season for the regular maintenance of
hand- pumps.
Hand-pumps are installed at depths established in accordance with the:
well yield: the lower the yield, the deeper the pump is installed;
the depth of water level;
the depth of water entries;
the number of users; and
the form of the village (if houses are close to each other or sparsely located; in the first
case water withdrawal is more intense in certain hours as women like to collect water
in company of their neighbors, thus creating a fast water level drop in low-yielding
wells).
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