Find the translation of the following terms and memorize them.

 

a single wall sheet-pile type	miscellaneous
cypress	cellular cofferdam	a crib dam
cofferdam	commonly	to bolt
to divert	circular	redwood
watertight	sheet-pile cells	crib
a pile	to tend	cedar
earth fill	mixture	shallow

 

Read the text to get the gist of it. Answer the following questions.

 

Are cofferdams permanent or temporary structures?

What timbers are the most durable?

 

Text F Miscellaneous Types of Dams

 

A timber crib dam is made of timber bolted into cribs and filled with rock. The life of a timber dam varies from 10 to 40 years depending upon climatic conditions and the type of timber used. Cedar, redwood and cypress are the most durable timbers. Where there is an adequate supply of timber, crib dams are quite inexpensive and generally satisfactory for heights not exceeding about 20 ft.

Cofferdams are temporary structures used to divert water from an area where the construction operations are to be conducted. A cofferdam must be relatively low in cost but as watertight as possible. The simplest kind of cofferdam is a single wall sheet-pile type, sometimes strengthened by an earth fill on both sides. A single wall sheet-pile cofferdam can be used only in very shallow water. For depths over about 5 ft cellular cofferdams are commonly used. These consist of circular sheet-pile cells filled with earth. A mixture of sand and clay is the best filler since clay itself tends to wash out through the gaps between the piles while sand is too permeable. Timber-crib dams are sometimes used as cofferdams. The simplest embankment often requires too much room because of the large base width necessary for an embankment of any height.

 

Comprehension Check

 

 

Decide whether the following statements are true or false according to the text.

1) A timber crib dam is made of timber bolted into cribs and filled with earth.

2) The life of timber dam is limited to 10 years.

3) Cedar, redwood, cypress are the most permanent timbers.

4) A cofferdam must be relatively low in cost but as hermetic as possible.

5) For depths over about 5 ft sheet-pile dam are commonly used.

6) A mixture of clay and sand is the worst filler.

7) The simplest embankment often requires too much place because of the large base width.

Answer the following questions.

1) What is a timber crib dam made of?

2) What does the life of a timber dam depend upon?

3) What are the most durable timbers?

4) What are cofferdams used to?

5) A cofferdam must be relatively low in cost but as watertight as possible, mustn’t it?

6) What is the simplest type of cofferdam?

7) Where can it be only used?

8) Why is the mixture of clay and sand the best filler?

9) Does the simplest embankment often require too much room? Why?

Make а short summary of text F.

Language Focus

 

Find in the text the synonyms of the following words.

 

a) mixed -...	c) hermetic -...	e) action -...
b) sufficient -...	d) solid -...	f) pervious -...

 

Find in the text the opposites of the following words.

 

a) expensive -...	c) deep -...	e) high -...
b) permanent -...	d) the worst -...	f) watertight -...

 

Build up the correct words.

Model: amd → dam

1) ibremt → …	6) ahetr → …	11) ionditcon → …
2) ircb → …	7) erlifl → …	12) ledubar → …
3) elip → …	8) veridt → …	13) poryramet → …
4) twidh → …	9) tihegh → …	14) meaperble → …
5) stoc → …	10) urextim → …	15) damferofc → …

Fill in the necessary preposition then choose any five items and make sentences.

1) to be made ___timber; 2) to use only ___ shallow water; 3) to be filled ___ rock; 4) a kind ___ cofferdam; 5) to vary ___ 10 ___ 40 years; 6) mixture ___ clay and sand; 7) to depend ___ conditions; 8) to wash out _____ the gaps; 9) to be low ___ cost; 10) to be used ___ cofferdams; 11) to be ___ watertight ___ possible; 12) because ___ the large base width; 13) to consist ___ circular sheet-pile cells; 14) to be necessary ___ an embankment ___ any kind.