Lesson Notes By Weeks and Term - Junior Secondary School 2

SUBJECT:  BASIC TECHNOLOGY       

CLASS:  JSS2

DATE:

TERM: 3RD TERM

REFERENCE MATERIALS 

• MELROSE, Basic Science and Technology Book 2
• NERDC, Basic Technology for JSS, Book 2

WEEK SEVEN

TOPIC: BUILDING CONSTRUCTION: SITE PREPARATION I

Site preparation involves the removal of trees, demolishing buildings, removing any and all old underground infrastructures, and any other things that might affect the construction process in the future or hinder the project to be done.

In various building projects, site preparation is very essential. The site may be a thick bush with big trees or a swampy and waterlogged area or a site with small hills and valley covered with stones and rock, or even a site with old and abandoned buildings.

TYPICAL HAND TOOLS IN SITE PREPARATION

Among the typical hand tools in site preparation operations are:

1. Spade: Used for digging relatively loose or soft earth
2. Shovel: Used for lifting and throwing loose materials (aggregates) or soft earth into another position and for spreading and leveling the earth.
3. Matchet: Used for cutting grasses or wood like tree branches and shrubs
4. Hoe: Used for digging usually about the surface level of the ground.
5. Axle: Used for cutting bigger branches. 
6. Chain saw: Used for felling trees and for cutting the trunk into smaller lengths

MECHANICAL TOOLS USED IN SITE PREPARATION

Mechanical tools, which are also very valuable in speedy operations of site clearing, tackle the bulk of the heavy jobs on the site. Among these are following:

1. Bulldozer: This is a very powerful machine, which can push down almost any obstacle on its way and clear them from the site. 
2. Tractor shovel (pay loader): This machine has a tipping bucket at the front. It is used for lifting large quantities of loose materials at a time and loading them into trucks or tippers. 
3. Grader is used mainly for grading, that is, for trimming of bank or edges of roads and for cutting ditches

REMOVAL OF VEGETABLE SOIL SMALL TREES AND SHRUBS

The bulldozer is moved in to push down unwanted structures like old buildings and to uproot trees and shrubs. This debris is moved away to the site where parts of the trees are later salvaged for firewood. The bulldozer then scraps or excavates the topsoil to a depth of between 150mm and 300mm for the entire surface area of the site. 

To prevent weed growth, an herbicide is applied. Herbicide is chemicals that are capable of preventing the growth of weeds when applied on a building site.

Herbicides

1. Round up:This is a general-purpose herbicide
2. Grammazon:This is another trade name for a type of herbicide used on building site.

Techniques for Grubbing out roots and stumps

It is better to first fell the trees, cut the trunk and transport to the sawmill for conversion into timber. The stump left is then tackled. Some digging is done around the tree stump to expose the roots, which are then cut either with an axe or the chain saw and the stump finally pulled out by the bulldozer.

LEVELING THE SITE

When all the tree stumps and roots have seen grubbed out and the top vegetable soil excavation to a depth of between 150mm and 300mm, a grader is moved in, to level the site. Here, earth is cut from the higher ground and moved down to fill valleys, holes and gullies.

EXTERMINATION OF TERMITES AND THEIR NESTS

When termite’s nests and anthills are found on the construction site they should be destroyed. The anthill is knocked down and some poisonous chemicals like Gamaline or antitermite chemicals are mixed and poured into the nest to kill the termites.

GENERAL EVALUATION

1. Explain Site Preparation 
2. State five (5)tools used in site preparation

READING ASSIGNMENT

Read about Setting out (NERDC Basic Tech. for JSS2 page123-126)

WEEKEND ASSIGNMENT

1. Which of the following is not a hand tools for site preparation? (a) spade (b) shovel (c) axle (d) grader
2. Which of the following is a mechanical tool used in site preparation? (a) matchet (b) bulldozer (c) chain saw  (d) hoe
3. Which of the following is used for lifting large quantities of loose materials at a time and loading them into trucks or tippers? (a) grader (b) bulldozer (c) matchet (d) chain saw
4. One of the anti-termite chemicals used to exterminate termites from sites is (a) Marline (b) Gamaline (c) Benzene (d) Ester 
5. Which of the following chemicals is used for general purpose prevention of the growth of weeds (a) Round up (b) Grammazon (c) Gamaline (d) Benzene

THEORY 

1. Explain the following processes (a) Techniques for Grubbing out roots and stumps  (b) Leveling the site. 
2. State the uses of three (3) mechanical tools used in site preparation