Class: Senior Secondary School 2 (SS2 / SSS 2)
Term: 3rd Term
Week: 6
Age: 16 years
Duration: 45 minutes
Subject: Building Construction
Curriculum Theme: Drainage Systems
Previous Lesson: Drainage Installation: Setting out and excavation of trenches.
Topic: DRAINAGE INSTALLATION
Subject Matter: Laying of drainage (pipe laying process) (alignment and gradient control)

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define drainage installation.
Explain the importance of setting out in drainage works.
Describe methods of controlling gradient in trench excavation.
List different types of drainage pipes.
Identify various methods for testing drainage systems.

Affective Domain:

Appreciate the importance of proper drainage for public health and sanitation.
Value accuracy and precision in setting out and pipe laying.
Show interest in learning practical skills related to building construction.

Psychomotor Domain:

Demonstrate the process of setting out for a drainage trench.
Show how to establish and check the gradient of a trench.
Participate in a practical simulation of laying drainage pipes.

Collaborate effectively with peers during practical activities.
Communicate clearly when discussing drainage installation procedures.
Work safely and responsibly during practical demonstrations.

Reference Materials

The following resources were used in planning this lesson:

Senior Secondary Schools Education Curriculum
State Unified Scheme of Work
Building Construction for Senior Secondary Schools, Book 2

Instructional Materials

The teacher will teach this lesson with the aid of:

Shovel
Digger
Head pan
Measuring tape
Lines and pegs
Boning rods
Spirit level
Sample drainage pipes (PVC, concrete)

Rationale for the Lesson

This lesson helps pupils understand the practical steps involved in installing drainage systems, which is important for ensuring proper waste disposal and maintaining sanitary conditions in buildings. It provides them with practical skills relevant to the building industry and everyday life.

Prerequisite/Previous Knowledge

Pupils should have basic knowledge of site preparation, excavation, and general safety measures on a construction site.

Lesson Content/Board Summary

DRAINAGE INSTALLATION

Introduction to Drainage Installation

Drainage installation involves the systematic process of laying pipes and fittings to collect and convey wastewater and stormwater away from a building or site. Proper installation is essential for sanitation, preventing waterlogging, and maintaining the structural integrity of buildings.

Setting Out for Drainage

Setting out is the process of accurately marking the position and alignment of the proposed drainage trenches and pipe runs on the ground. It ensures that excavations and pipe laying follow the design specifications.

Key steps in setting out include:

Marking the trench centerline using pegs and lines.
Establishing the width of the trench.
Transferring levels from a known benchmark to determine excavation depths.

Gradient Control in Trenches

The gradient (or fall) is the slope of the drainage pipe, which ensures that wastewater flows by gravity. Maintaining the correct gradient is critical for efficient drainage and preventing blockages.

Methods for controlling gradient include:

Boning Rods: Three boning rods of equal length are used to establish a consistent fall. One rod is held at the start of the trench, another at the end (adjusted for the required fall), and the third is used to check intermediate points.
Spirit Level: A spirit level can be used on a straight edge to check the fall over shorter distances, often with a packing piece to achieve the desired slope.
Automatic Levels/Laser Levels: More advanced equipment provides precise level and gradient control over longer distances.

Laying of Drainage Pipes

Pipe laying involves placing the drainage pipes in the excavated trench according to the correct alignment and gradient. Joints must be sealed properly to prevent leakage.

General procedure for pipe laying:

Ensure the trench bed is firm, even, and at the correct gradient.
Lay pipes starting from the lowest point (outlet) and working upwards towards the inlet.
Ensure each pipe is accurately aligned and set to the correct gradient using a spirit level or boning rods.
Join pipes securely using appropriate fittings and jointing materials (e.g., rubber rings, solvent cement for PVC, mortar for concrete pipes).
Support pipes properly, especially at joints and changes in direction.

Types of Drainage Pipes

Various materials are used for drainage pipes, each with specific properties:

PVC (Polyvinyl Chloride) Pipes: Lightweight, easy to cut and join, corrosion-resistant, commonly used for internal and external drainage.
Concrete Pipes: Strong, durable, suitable for heavy loads and larger diameters, often used for storm drains and main sewers.
Cast Iron Pipes: Very strong and durable, resistant to high temperatures, traditionally used for soil and waste pipes, but less common now due to cost and weight.
Clay (Vitrified Clay) Pipes: Resistant to chemical attack, durable, good for underground drainage, but can be brittle.

Methods of Testing Drainage Systems

After installation, drainage systems must be tested to ensure they are watertight and functioning correctly, preventing leaks and blockages.

Common testing methods include:

Water Test: The most common method. All outlets are plugged, and the system is filled with water to a specified head. The water level is observed over a period (e.g., 30 minutes) to check for any drop, which would indicate a leak.
Air Test: The system is sealed, and air is pumped in to a specific pressure. A pressure gauge is used to monitor for any drop in pressure, indicating a leak.
Smoke Test: Smoke is introduced into the system, and if any smoke escapes from joints or cracks, it indicates a fault. Used to detect foul air leaks.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids, Practical work

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and asks them to recall previous lessons on site preparation and excavation. The teacher then introduces the topic of drainage installation and its importance.
Pupils’ Activity: Pupils respond to the teacher’s questions and listen attentively to the introduction of the new topic.
Learning Point: Pupils connect the new topic to prior knowledge and understand its relevance.

Step 2: Explanation of Setting Out

Time: 8 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher explains the concept of setting out for drainage trenches, using a diagram or a small practical area to illustrate how lines and pegs are used to mark the trench alignment.
Pupils’ Activity: Pupils observe the demonstration, ask questions, and discuss the importance of accurate setting out.
Learning Point: Pupils understand the procedure and importance of setting out for drainage.

Step 3: Understanding Gradient Control

Time: 8 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher explains the concept of gradient (fall) in drainage and demonstrates how to establish and check it using boning rods and a spirit level.
Pupils’ Activity: Pupils pay attention to the explanation and demonstration, noting the practical application of gradient control.
Learning Point: Pupils learn how to achieve and maintain the correct gradient for effective drainage.

Step 4: Laying of Drainage Pipes

Time: 7 minutes
Teaching Skill: Explanation/Practical Guidance
Teacher’s Activity: The teacher explains the step-by-step process of laying drainage pipes, emphasizing alignment, jointing, and securing pipes in the trench.
Pupils’ Activity: Pupils listen to the instructions and observe any practical examples or illustrations provided.
Learning Point: Pupils learn the correct procedure for laying drainage pipes.

Step 5: Types of Drainage Pipes

Time: 5 minutes
Teaching Skill: Lecture/Categorisation
Teacher’s Activity: The teacher explains and lists different types of drainage pipes, such as PVC, concrete, and cast iron, discussing their characteristics and uses.
Pupils’ Activity: Pupils listen and take notes on the various types of drainage pipes and their applications.
Learning Point: Pupils identify and differentiate between common drainage pipe materials.

Step 6: Methods of Testing Drainage Systems

Time: 7 minutes
Teaching Skill: Explanation/Discussion
Teacher’s Activity: The teacher explains the importance of testing drainage systems after installation and describes common testing methods like the water test and air test.
Pupils’ Activity: Pupils listen to the explanations and ask questions for clarification on the testing procedures.
Learning Point: Pupils understand how drainage systems are tested for leaks and functionality.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

What is drainage installation?
Explain the importance of setting out in drainage works.
How can the gradient of a drainage trench be controlled?
Mention three types of drainage pipes.
Describe one method of testing a newly installed drainage system.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the importance of proper drainage installation. The teacher then gives homework, asking pupils to research local regulations for drainage installation.
Pupils’ Activity: Pupils listen to the summary and copy down the homework assignment.
Learning Point: Pupils consolidate their understanding and are encouraged to continue learning.

Lesson Keywords

Drainage Installation – The process of laying pipes and fittings to remove wastewater and stormwater.
Setting Out – Marking the exact position and alignment of construction elements on the ground.
Gradient – The slope or fall given to a pipe to ensure gravity flow.
Boning Rods – Tools used to establish and check the correct gradient in a trench.
Alignment – The straightness or correct positioning of pipes in a line.
Water Test – A method of testing drainage systems for watertightness by filling them with water.

Differentiation

For pupils who grasp concepts quickly, the teacher can encourage them to research advanced drainage systems or local building codes related to drainage. For pupils needing additional support, the teacher can provide simplified diagrams and offer more direct guidance during practical demonstrations of setting out and gradient control.

Note for teachers using this lesson plan

Teachers should emphasize safety precautions during any practical demonstrations involving excavation or pipe handling. Where actual materials are not available, visual aids, videos, and detailed diagrams should be used to illustrate the processes effectively. Encourage pupils to relate the lesson to real-life applications in their communities.