60. 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?

61. Make а short summary of text F.

62. Find in the text the synonyms of the following words.

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

63. Find in the text the opposites of the following words.

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

64. 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 → …

65. 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.

66. Translate from Russian into English.

1. Из лесоматериала делается ряж, который заполняется землёй.

2. Срок службы дамбы зависит от климатических условий и типа выбранного лесоматериала.

3. Коффердам должен быть как можно более водонепроницаемым.

4. Однорядная шпунтовая перемычка может использоваться только на мелководье.

5. Самый лучший наполнитель – смесь глины и песка.

6. Даже самой простой плотине нужно много места из-за большой ширины основания, необходимой для плотины любой высоты.

67. Fill in the gaps with the right word.

a) periphery	e) moves	i) blanket
b) drainage	f) prevent	j) upper
c) less	g) Drains	k) drain
d) toe	h) water

1)______ usually consist of a rock toe or a drainage 2)______ of coarse material in which seepage water collects and 3)______ to a point where it can be safely discharged. To 4)______ movement of fine materials from the dam into the 5)______, the drain material is graded from relatively fine on the 6)______ of the drain to coarse near the centre. A 7)______ blanket extends farther under the dam than a rock 8)______ does. If a pervious foundation layer is overlain by a 9)_______ pervious layer, relief wells or drain trench through the 10)_____ layer may be necessary to permit escape of seepage 11)______.