Design and Construction Method for Deep Tubewells Considering Different Hydrological Parameters

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Sajal Kumar Dutta

Shankar Kumar Debnath

Achinto Kumar Chakrabortty



September, 2001


Surface water is abundant in the wet season in Bangladesh. But during dry season, ground water ought to be the principal dry season source of water available in many areas in Bangladesh having agriculture potential. It is generally utilized where irrigation from surface source is difficult or impossible and water demand is high. Ground water pumping was, therefore, eminent and drilling and construction of deep tubewell were getting popular in almost all the areas except few spots because of either suspected or controversial lithological characteristics.

Although groundwater in Bangladesh is said to be abundant, a considerable areas of the country faces scarcity of groundwater within suction limit in the dry season. Due to the setting up tubewells in unplanned manner and over-exploitation of groundwater for irrigation purposes, the water level declines, rendering thousands of suction modes of shallow tube wells and deep-set hand pump tubewells inoperable. This project work deals with the design of deep tubewell with reasonable specific drawdown to overcome hazardous situation for more groundwater for irrigation in the dry season.

The important aspects of the work is to describe the formation samples and designing the tube well in order to minimize the amount of head loss due to movement of water through the aquifer. The lower the head loss, the smaller the drawdowns, less fuel have to be used to pump the water. We introduced a design system, which would make the specific drawdowns of the tubewells lower and more uniform than the existing deep tubewells by giving a logical flexibility in determining screen length and well depth to the designers at the site. The drilling is normally done with 18 to 22 inches size cutter. Good aquifer of sufficient length is desirable to install single string screen, which are sufficient to produce desired discharge (2 to 3 cusec) with specific drawdown 5 to 10 ft/cusec.



Acknowledgment I
Abstract II

List of Tables III

List of Figures IV

List of Photographs V

Chapter 1 Introduction 1

1.1 General 1
1.2 Objectives 2

Chapter 2 Review of Literature 3

Chapter 3 Terminologies 5

Chapter 4 Well Drilling 11

4.1 Site Preparation and Setting up 11 4.2 Drilling Technique 15 4.3 Sample Collection 19 4.4 Sample Description 20 4.5 Sieve Analysis at Site 22 4.6 Laboratory Sieve Analysis 23

Chapter 5 Tubewell Design 25

5.1 Components of Tubewell Casing 25
5.2 Materials of Tubewell Casing 25
5.3 Historical Tubewell Design 25
5.4 Project Tubewell Design 28
5.5 Aquifer Material Permeabilities 29 6. Length of Upper well Casing Design 31
7. Specification of Upper Well Casing 34
5.8 Lower Well Casing Design 37 5.8.1 Introduction 37 5.8.2 Design and Penetration Factors 39 5.8.3 Design Calculation 41

5.9 Specification of 8 inch...