Testing drains

1.Memorise the following technical words:

ball test – проверка гладкости внутренней поверхности трубы

block – засорять, закупоривать

blockage – засорение, образование пробки

hydraulic test – гидроиспытание, проверка на герметичность

mirror and torch test – испытание трубы с целью исключения отклонения от оси

plug – пробка, заглушка; затыкать пробкой, ставить заглушку

repair – ремонт, ремонтировать

replace – заменять

secure – надежный, прочный, безопасный

top up –доливать, досыпать

2. Study the meanings of the following misleading words:

test – испытание, проверка; проверять, испытывать;

interior – внутренняя часть;

3. Read and translate the text:

Drains that carry sewage must not leak into the surrounding ground. To make sure that the joints are secure, drains should be tested before they are covered up. The test is usually set up by the builder and checked by a building inspector.

You can use three different methods to test drains:

1. the hydraulic test;

2. the ball test;

3. the mirror and torch test.

To check that the drains are watertight you follow these steps for the hydraulic or water test:

1. Plug the lower end of a drain run.

2. Insert a temporary joint and 1.5 metre length of pipe at the higher end.

3. Pour water in the drain until the upright pipe is full.

4. Leave it for two hours.

5. Check the levels.

6. Top the water levels up.

7. Check the levels again after half an hour.

The level should drop less than 6.4 mm per metre of 100 mm pipe or 4.5 mm per 150 mm pipe. If the drop in the water level is greater than this, then you must inspect the pipe for leaks and repair or replace it.

The ball test checks that the pipe interior is clear of obstructions that could cause a blockage. You roll a ball that is slightly smaller than the diameter of the drain down its length. If the ball stops, then the drain is blocked and must be cleared out.

The mirror and torch test checks that the drain is straight. If a mirror is fixed at one end of the drain and you shine an electric torch from the other end, then you should see the reflection of the torchlight in the mirror.

4. Answer the questions:

1. What are three methods for testing drains? 2. What is the hydraulic test used for? 3. What does the ball test check? 4. What does the mirror and torch test check? 5. Who carries out the test?

Text 9 (1800)

Building a manhole

1.Memorise the following technical words:

base – основание

bricklayer – каменщик

brickwork – кирпичная кладка

connection – соединение

cover=manhole cover – крышка смотрового колодца

haunching – пята трубы

open channel – лоток (канализационной трубы)

render – штукатурить, обмазывать

2. Read and translate the text:

A manhole or inspection chamber is located on a drain run at points where several drains meet or there is a change of direction. You use a manhole to inspect and clean the underground drainage system. Figure 3. shows you the construction details for a manhole.

The depth of a manhole depends on its position on the drain run. The farther it is from a building, the deeper the manhole because of the fall in the drain.

The size of a manhole depends on the depth of a drain and the number of connections. If the drains are very deep, then a manhole must have working space inside it. However, this is not com­mon in domestic drainage systems.

If the drain is straight and there are no connec­tions, then the manhole must still be a minimum size of about 300 mm.

Figure 3. Details of typical manhole construction: (a) section of a manhole excavation; (b) branch drain entering an open channel; (c) brickwork and backfill in a manhole; (d) section of a manhole showing the branch connections; (e) section of a manhole after construction.

Table 4 shows the typical recommenda­tions for manhole dimensions.

Table 4 Manhole dimensions

Depth of manhole	Length of manhole	Width of manhole	Cover size
(metres)	(mm)	(mm)	(mm)
Up to 1.0	450	450	450 x 450
1.0-1.5	1200	750	600 x 600

Making a brick manhole. You begin by excavating to the recommended depth in the correct position. The bricklayer will need enough space to work in. You should also leave space for a concrete base that is larger than the outer brickwork.

In normal conditions you should add about 100 mm to the size of the manhole cover to find the correct size for the base. For example if a manhole opening is 600 x 450 mm and the walls are 102.5 mm thick, then the overall size of the manhole should be 805 x 655mm. The base size should be 905 x 755 mm.

Table 5 describes the procedure for making a brick manhole.

Table 5 Making a brick manhole

Step	Action
1	Cast the concrete base.
2	Build up the walls and build in the drains which pass through them.
3	Bed the open channel sections and branch connections of the drains in the base.
4	Fill in the spaces between the branches with concrete (this is called haunching). The haunching in between the branches and the wall should be smooth and slope to the channels to keep the bottom of the manhole clean and dry.
5	When the brickwork is completed, render it in a 1:3 cement and sand mixture to make it watertight.
6	Make a brick shelf at the top or lay a precast concrete slab over the top of the manhole if the frame for the cover is smaller than the base.

Notes:

cast the concrete base – забетонировать основание, залить бетонное основание

3.Answer the questions:

1.What is a manhole built for? 2. What does the size of a manhole depend on? 3. What is haunching? 4. What has to be done if the frame of the manhole cover is smaller than the base?

Text 10 (2600)