The Deep Tubewell Drilling Site was located at Likhu Rural Municipality, Nuwakot. The GPS Coordinate of the well drilling site is 27°54’46.53”N, 85°12’41.33”E which is about 407.5 m south road distance from Princika Krishi Firm.
After Site Mobilization, the drilling work on the site at Likhu Rural Municipality, Nuwakot was started on 2080/02/26. The drilling work was continued smoothly and achieved 120 m of penetration. After this depth, the drilling work was stopped as the well has penetrated sufficient depth. During the drilling operation, representative sample of each layer were collected. The driller has also prepared litholog on the basis of cuttings, nature of progress of the well penetration. According to driller’s lithological log & well penetration rate, the well was designed. The whole drilling work was carried in the direction and close supervised of office representative. The lithological log of the Tube well is presented .On the basis of aquifer layer presence of the well the screen pipe and casing pipe were lowered after the completion of the drilling work.
Total length of casing and screen used
200 mm MS Casing Pipe – 48 m
200 mm Perforated Screen – 24 m
150 mm MS Casing Pipe – 18 m
150 mm Perforated Screen – 30 m
Total length – 120 m
Note: +0.5 m above the ground level.
Lithology
The well development by air compressor and pump test work was done after installation of Tube well. Compressor was used during drilling time and Development of tube well by pump has been carried out immediately after installation of the pipe assembly. The well development has broad objectives:
-To repair damage done to the formation (aquifer) by the drilling operation so that the natural hydraulic properties are restored
– To alter the basic physical characteristics of the aquifer near the borehole so that the water will flow more freely to the well.
Continuous Pumping Test
The continuous test was conducted by using submersible pump. In this test, the well was pumped at constant rate for 12 hours The pumping test data and measurement taken during the pumping test are shown in Annex A. The static water level was 5.5 m. The dynamic water level after 12 hr. was 75.2 m at 2.5 lit/sec discharges and the Transmissivity is:
Transmissivity (T) = 9.16*10-5 m2/sec
Hydraulic Conductivity (K) = 1.53*10-6 m/sec
Recovery Test
After 12 hours of pump operation, constant rate pumping test was stopped. Recovery test was conducted immediately after pump had stopped. It took 1 hour 55 minutes to recover water level to initial level.
Conclusion
The well was drilled up to the depth 120 meters below the ground surface. The Perforated screen pipes were installed on the basis of aquifer presence on the well. Perforated screen of 3.2 mm screen opening size were used in well. Well was developed by air compressor for 24 hours a tube well’s performance was satisfactory and was successful.