Exercise 30. Match the words to make phrases.

1) to be cleared; 2) proposed; 3) filled up; 4) stretching; 5) row; 6) suitable;

a) strings; b) with soil; c) of pillars; d) off; e) distance; f) foundation.

Exercise 31. Match the description of plants with their names.

1. Face shovel excavators.

2. Backactors (Backhoe).

3. Bulldozers.

4. Tractor shovel (loading shovel).

5. Clamshell excavator.

6. Powered shovel or drill.

1.________________________________	They can be cable or hydraulic operated, mounted on wheel or track. They are fitted with a bucket which faces away from the machine. They are used for loosening, excavating vertical or near-vertical soil above the machine base level. They are not suitable for horizontal or below ground excavation.
2._____________________________	They are used for below ground level excavation. They are used mainly for trench or large scale open excavation, but sometimes they are also used as loading machines.
3._____________________________	They are traditionally track mounted tractors with significant weight so that they can work easier with soil. They are usually fitted with a straight or angled blade which can be slightly raised by hydraulic action to adjust level. They are used for grading materials to levels over relatively smaller area, to cut small trees, remove surface vegetation or hard surfaces etc. The max cut is about 400 mm below base of the machine.
4. ___________________________	This machine is similar to a bulldozer but has a hydraulic operated bucket in place of the blade. Materials above the base of the vehicle can be lifted and unloaded onto a dump truck or onto a spoil heap. The bucket size varies from 0.5 m3 to 3 or 4 m3 depending on capacity of machine.
5._________________________	This is somewhat a crane, usually track mounted with a wire operated clamshell. It is used to handle or load soft soil on site. It is more useful in a very big site where a large amount of soil materials is required to remove.
6. _______________________________	This is for cutting larger boulders or rock. Usually the drill is pneumatically operated and mounted on a tracked base. Very often, it is convertible to a backactor with the bucket replaced by the drill to gain flexibility and minimize capital input.

Exercise 32. Watch the video 2.1 and answer the questions.

EXCAVATION AND TRENCHING SAFETY

https://www.youtube.com/watch?v=29lCiaj3OIk

1. What is excavation according to the video?

2. What is a trench? How is it measured?

3. What are trenching hazards?

4. When does caving occur?

5. What happens when oxygen disappears?

6. When can materials that fall into excavation cause injuries?

7. How far should objects be placed from the excavation?

8. Why is water so dangerous for excavation?

Exercise 33. Brainstorm problems that can occur during excavation and discuss solutions in the group. Complete the following table.

Excavation problems	Solutions

Exercise 34. Read the e-mail from a contractor to a project manager. Then, mark the statements as true (T) or false (F).

1. _____ The worksite was flooded by runoff.

2. _____ The crew cannot use a sump to solve the problem.

3. _____ Work cannot continue until the water table is lowered.

Dear Randy,

I just wanted to let you know about a delay in construction. We ran into a problem during today’s excavation. While drilling, we encountered a large amount of seepage from groundwater. The water table in this area was unexpectedly high. Before we can proceed, we need to extract the water.

Since this isn’t runoff or standing water, it won’t be possible to let the water collect in a sump. The best way to solve this problem is by lowering the water level with a dewatering system. We will install a series of well-points throughout the area. As the water fills the well-points, we will use a pump to empty them. We will have to lower the water table by several feet.

I expect the process to take a few days. In the meantime, our crews will check the other areas of the construction site and make sure that this isn’t a problem anywhere else.

If you have any questions, feel free to call me.

Marcus Adams