Understanding Groundwater & Wells in manual drilling April 2008 An instruction manual for manual drilling teams on hydro-geology for well drilling, well installation and well development Illustration on cover: Hydro-geology and hygiene in relation to well drilling Published by the PRACTICA Foundation Maerten Trompstraat 31 NL-2628 RC Delft …

Groundwater & Wells in manual drilling ETC Energy / UNICEF 4 April 2008 Introduction Making a well The construction of a well, using manual drilling techniques is a complicated process. Before drilling starts a good drilling site has to be selected, where experience suggests that there will be an adequate quantity of good quality groundwater. During the drilling process there are a lot of different aspects which require attention to prevent things from going wrong. Besides the practical drilling skills which are executed at ground level, at the same time attention has to be paid to important processes which are happening below ground level during drilling. Water used in drilling (working water) could flow away or worse; the borehole could collapse, burying part of the drilling equipment. And finally, once the hole has been drilled, the well casing, screen and sanitary seals have to be installed at the right depth, preventing contaminated water from entering, and ensuring a sufficient yield. In many countries manual drilling teams experience problems with site selection, loss of working water, soil determination, logging, well installation, well development, water quality and well yield (flow rate of the well). These problems may occur when the drilling process is not completely understood and important steps are missed. This instruction manual describes many of the subjects and problems which you may come across during drilling. The manual will help you to understand the drilling process at ground level and far below ground level in the drilled hole. With the information provided you will be able to understand what is taking place in the hole during drilling, and perform a professional job as you construct high quality water wells. The Manual How does this instruction manual work? In the table of contents (see previous page) an overview is given of the subjects and where to find them. Chapter 1 to chapter 8 contains all the information needed for a good understanding of the drilling process and correct well installation. In the Appendix you will find country specific regulations. These are regulations designed for communal wells and defined by the government or NGO you are working for. In the Appendix you will also find some specific geological conditions, which are unique for the area or country you work in. Furthermore, simple ‘blank’ drilling logs are included, which can be copied for use in the field. Additional information For more detailed background information for policy makers, project managers, implementing NGOs, trainers and supervisors, some useful titles of existing books and manuals are given at the end of this instruction manual.

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