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close this bookWater and Sanitation Technologies: A Trainer's Manual (Peace Corps, 1985)
close this folderSessions
close this folderSession 27 - Principles of hand-dug shallow wells
View the document(introduction...)
View the documentAttachment 27A: Large diameter tube wells

(introduction...)

TOTAL TIME

Two Hours

OBJECTIVES

* Identify factors that determine a suitable site for a hand dug shallow well


* Explain, in detail, various methods of constructing shallow tube wells


* List proper safety practices that should be followed during well construction


* Describe the construction steps necessary for a shallow well project.

RESOURCES

Small Community Water Supplies; IRC, pp. 100-131


Rural Water and Sanitation Projects; USAID, pp. 107-129


Wells Construction; Peace Corps ICE, Chapters 1-9


Attachment 27-A: "Large Diameter Tube Wells"

PREPARED MATERIALS

Newsprint and felt-tip pens


Slides or sketches of well project construction steps, slide projector and screen, copies of the Attachment for all trainees, reproductions on newsprint of Figures 1, 2 and 3 from the Attachment

FACILITATORS

One or more trainers

Trainer Introduction

This session is designed to provide detailed information about the construction of hand-dug shallow wells. It concentrates on large diameter tube wells using reinforced concrete for a lining. This is the method of construction that will be used to rehabilitate an existing shallow well during Session #30. If an alternative method of construction is more appropriate for your training program, substitute an explanation of that method(s) during Step 3.

The slide or sketch presentation should concentrate on the method of construction you plan to use during the training program. Prepare the presentation prior to the session. The reading assignment is long and therefore, trainees should be told of the assignment well in advance. Hand out the attachment prior to the session.

PROCEDURES

Step 1

5 minutes


Present the objectives and format for the session

Step 2

15 minutes


Ask trainees to identify criteria that determine a suitable well site.


List the responses on newsprint.

Trainer Note

Most of the criteria will fall under three general headings: community, hydrology, and topography. Lead a discussion about each heading. Below are factors to consider:

*HYDROLOGY

Geology: Soil type (sand, clay, gravel, boulders), water bearing capacity of soils, suitability for safe digging

Aquifer: Depth, size, water quality, recharge (test drilling may be necessary if there are no existing wells nearby)

*TOPOGRAPHY

Contamination: Locating all possible sources of contamination, listing methods to protect well or remove contamination

*COMMUNITY

Community: Well accessibility, project acceptance, project support
Labor: Availability of human and material resources for construction, operations, and maintenance.

Step 3

45 minutes


Refer to Attachment 27-A. Describe the components, construction sequence, strengths, and weaknesses of large diameter hand-dug shallow tube wells.

Trainer Note

Review the information presented in the Attachment with the trainees. Use your reproductions on newsprint of Figures 1, 2 and 3 to illustrate important points.

Step 4

20 minutes


Discuss proper safety practices during well construction.

Trainer Note

Emphasize that good safety practices are as easy to follow as poor safety practices. If good practices are instigated from the beginning, and followed by all participants, they quickly become part of the normal work routine. Here are some safety points to mention:

1. Check all equipment before construction begins. This includes ropes, pulleys, tripods, buckets, digging tools, handles, ladders and all other necessary equipment. Buying quality equipment also helps greatly. It may cost more money initially, but soon pays for itself in terms of safety and efficient use.

2. Guard the area around the well hole at all times to prevent material from falling down the hole. This is true when work is in progress and when it is not. Objects falling down the hole can seriously injure people digging. Also, an unattended and uncovered hole is a serious community hazard. Equipment should be kept in a central location and always returned there after being used.

3. A well should always be lined during excavation (unless the earthen strata is extremely stable) to prevent collapse. No more than 5 meters should be dug before the lining is put in place and for many types of soil, this figure will be even less. Once put in place (temporarily or permanently) the lining should be checked regularly.

4. Asphyxiation can be a serious problem during digging. This is especially true in deep wells or when gasoline powered pumps are lowered into a well to drain the water. Ventilation is poor in wells. Therefore, if gases have built up, no one should go down into the well until the air has cleared.

5. A lead person should be designated and always stand near the top of the well to keep in contact with those down below. This person should monitor all safety procedures.

Step 5

30 minutes


Illustrate the construction steps necessary for a shallow well project.

Trainer Note

Again, illustrate the method of construction that will be used during the training program. The following steps should be illustrated:

- Site Selection

accessibility, water quality and quantity, ease of construction

- Site Preparation

Safety procedures, collection of materials, tools and equipment

- Excavation

Safety procedures, desired depth and width

- Lining

Safety procedures, desired method of lining

- Sanitary Seal

Complete protection from contamination

- Retrieving Water

Appropriate method for community

- Operations/Maintenance

Plan and ongoing program

Step 6

5 minutes


Review the objectives and conclude the session.