Water Conservation Program

GSDA is implementing schemes to improve the performance of the existing ground water sources and strengthening the sources by unconventional measure.

Sources strengthening by unconventional measures as on today

Principle and general description of the above technique is given below.

1. FRACTURE SEAL CEMENTATION

The groundwater migration through a network of shallow depth aquifer from the discharging location is arrested by this technique. It is suitable in disintegrated rock combined with fracture and granular porosity. After identifying the suitable area on the basis of geohydrological investigations, this technique is adopted. Under this process, normally one or two rows of suitable diameter boreholes are drilled to a depth of a little more than the deepest dug well in the command area of stream or all. These rows across the stream are filled by injecting cement slurry under high pressure for sealing of existing fracture. This technique is used to create an effect of “ Cut Off Wall “ as Underground band hard.

2. JACKET WELL

The construction of Jacket well around the dug well in hard rock area increases the effective diameter of the well artificially thereby increasing the storativity. Borewells of about 115 mm diameter and to a depth of open dug well or to a shallow aquifer are drilled around the supply well, either in circular or semi-circular or any other desired pattern depending upon the topographical and hydrological conditions. The blasting of these bores is carried out using slurry explosives, detonating cord and electrical detonators to create fractures and interconnection between the boreholes to increase the effective diameter of supply well and to create additional storativity of water.

3. BORE BLAST TECHNIQUE

Bore blast technique is adopted to create more storage space of Groundwater artificially in massive and crystalline hard rocks by fracturing the bed rocks.

The hydrogeological survey is carried out to locate such area where the rock can be blasted to develop cracks below the zone of weathering. The no of boreholes is calculated depending on the quantity of water to be made available. Suitable type of slurry explosive is lowered in the boreholes and is blasted using detonating cord and electrical detonators. At a time about 5 to 6 boreholes are blasted. This technique is applied in assured rainfall areas and where landforms are mostly hilly. These are most suitable for small habitations of about 100 to 150 population, where drinking water shortage occurs.

4. HYDRO FRACTURING

This technique is applied for rejuvenation of poor yielding or Unsuccessful borewells. Some of the borewells in the villages are successful and fitted with the pumping device. Poor yielding and dry borewells in the same village indicate that the fractures do not exist or if existing, they are not connected to the nearby bodies, and the fractures may be closed or sealed.

By this technique, the very high hydraulic pressure is created between the confined sections of the borewell. This very high pressure is responsible for opening the closed or sealed fractures and further connecting it to nearby bodies. When the confined section of borewell is not having existing network of fractures then the new fractures are created and these newly created fractures are further extended to connect the water bodies. In this way, borewell yield is improved substantially.

5. STREAM BLASTING

Generally, drinking water wells are situated on all banks.
However, at some places the groundwater flow through all bed is not connected to the well and therefore these groundwater goes waste as a runoff and the well-being not connected becomes dry during summer months. Such wells are possible to be rejuvenated by a technique known as “ Stream Blasting”.

In this technique, the area of all bed in the vicinity of well is studied by the geophysical and geohydrological survey. Then numbers of 115 mm borewells are drilled in the all bed to a depth of open dug well. These drilled boreholes are further charged with explosives and blasted to artificially to create fractures joints etc. Such artificially created fractures are automatically got interconnected to the well and groundwater is made available thereby improving the drinking status of the well.

6. STORAGE PIT

Normally the hilly terrain in the state receives satisfactory Rainfall. But due to steep gradient, thin soil cover, limited weathered mantle and absence of joints and fractures information cause meagre storativity for groundwater. Ultimately the habitations located in such area faces acute scarcity of drinking water in every summer. In such areas, the conventional measures have limited utility due to technical and financial factors. The measures like “ Storage Pit “ is used to collect water in required proportion with population. Small habitations ( Up to 200 souls ) are considered for this measure.

In this project, the size of the pit is fixed by volumetric analysis in accordance with population. Quantity loss due to evaporation and other permissible seepages is also taken into account. Pit of required volume is excavated and kerbed up to hard strata, same as dug well. To check the migration of stored water, pit wall at the downside is sealed by the concrete lining. Normally the pits are open, but in cases to protect the pollution and evaporation, the pit is totally filled with coarse sand, pebbles and boulders as filter media.
From the pit, water is pumped by shallow depth hand pump, which will be installed on a safe distance from the pit to avoid pollution.

These projects may be implemented in combination as per site requirements.