Unit 3.2 Sewerage. Definitions

Read the text and give the tittle to it. Word the main idea of the text.

As cities have grown, the more primitive methods of excreta disposal have given place to the water-carried sewerage system. Even in small towns the greater safety of sewerage, its convenience, and freedom from nuisance have caused it to be adopted wherever finances permit.

Sewerage implies the collecting of wastewaters from occupied areas and con­veying them to some point of disposal. The liquid wastes will require treatment before they can be discharged into a body of water or otherwise disposed of without endangering the public health or causing offensive conditions.

Sewage is the liquid conveyed by a sewer. It may consist of any one or a mixture of liquid wastes which will be separately defined. Sanitary sewage, also known as domestic sewage, is that which originates in the sanitary conveniences of a dwel­ling, business building, factory, or institution. Industrial waste is a liquid waste from an industrial process, such as dyeing, brewing, or papermaking. Storm sewage is liquid flowing in sewers during or following a period of rainfall and resulting there from. Infiltration is the water that has leaked into sewers from the ground. Inflow is water which enters sewers from surface sources such as cracks in manholes, open cleanouts, perforated manhole covers, and roof drains or base­ment sumps connected to the sewers. Inflow occurs only during runoff events.

A sewer is a pipe or conduit, generally closed but normally not flowing full, for carrying sewage. A common sewer is one in which all abutting properties have equal rights of use. A sanitary sewer is one that carries sanitary sewage and is designed to exclude storm sewage, surface water, and groundwater. Usually it will also carry whatever industrial wastes are produced in the area that it serves. It is occasionally, although improperly, called a separate sewer. A storm sewer carries storm sewage, including surface runoff and street wash. A combined sewer в designed to carry domestic sewage, industrial waste, and storm sewage. A sewer s tem composed of combined sewers is known as a combined system, but if storm sewage is carried separately from the domestic and industrial wastes, it is said to be a separate system. The term sewerage is applied to the art of collecting, treating, and disposing of sewage. Sewerage works or sewage works are comprehensive terms covering all the structures and procedures required for collecting, treating, and disposing of sewage.

A house sewer is a pipe conveying sewage from the plumbing system of a single building to a common sewer or point of immediate disposal. A lateral sewer has do other common sewer discharging into it. A submain sewer is one that receives the discharge of a number of lateral sewers. A main sewer, also known as a trunk sewer, receives the discharge of one or more submain sewers. A sewer outfall receives the discharge from the collecting system and conducts it to a treatment plant or point of final disposal. An intercepting sewer is one that cuts transversely a number of other sewers to intercept dry-weather flow, with or without a determined quantity of storm water, if used in a combined system. A relief sewer is one that has been built to relieve an existing sewer of inadequate capacity.

Sewage treatment covers any process to which sewage is subjected in order to remove or alter its objectionable constituents so as to render it less dangerous or offensive. Sewage disposal applies to the act of disposing of sewage by any method. It may be done with or without previous treatment of the sewage.

Read the text again and make up a plan of it. Choose the key-words from the text to each point of your plan.

2. Look through the text again and make up a summary of it. Use the following phrases:

• The text deals with…

• It covers such points as…

• It is pointed out that…

• Much attention is given to…


Unit 3.3 Sources of Sewage

Read the text and answer the questions:

1) How are sewers classified?

2) What is called sanitary sewage?

3) What is called industrial waste?

4) What type of sewage carries all kinds of waste?

5) What are sanitary sewage and industrial waste derived from?

Sewage is defined as a combination of (a) the liquid wastes conducted away from residences, business buildings, and institutions; and (b) the liquid wastes from industrial establishments; with (c) such ground, surface, and storm water as may be admitted to or find its way into the sewers. Sewage a is frequently known as sanitary sewage or domestic sewage. Sewage b is usually called industrial waste. Sewers are classified according to the type of sewage that they are designed to carry. Sanitary sewers carry sanitary sewage and the industrial wastes produced by the community and only such ground, surface, and storm water as may enter through poor joints, around manhole covers, and through other deficiencies. Storm sewers are designed to carry the surface and storm water which runs off the area that they serve. Combined sewers carry all types of sewage in the same conduits.

The following discussion has for its purpose the development of methods of estimating the quantity of sewage that is or would be carried by sanitary sewers, i.e., wastes from residences, business buildings, institutions, industrial plants, and such water as may enter incidentally.

Sanitary sewage and industrial waste will obviously be derived largely from the water supply. Accordingly, an estimate of the amount of such wastes to be ex­pected must be prefaced by a study of water consumption, either under present conditions or at some time in the future. The proportion of the water consumed which will reach the sewer, must be decided upon after careful consideration of local conditions. Water used for steam boilers in industries, air conditioning, and that used to water lawns and gardens may or may not reach the sewers. On the other hand, many industrial plants may have their own supplies but discharge their wastes into the sewers. Although the sewage may vary in individual cities from 70 to 130 percent of the water consumed, designers frequently assume that the average rate of sewage flow, including a moderate allowance for infiltration, equals the average rate of water consumption.

1. Look through the text again and complete the following sentences:

1) Sewers are classified according to…

2) The proportion of the water consumed must be decided upon…

3) The sewage may vary in some cities from…to…

4) Designers assume that the average rate of sewage flow equals…

5) Domestic sewage is…


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