8/14/2019 87444629 PPT on Sewer Design

1/16

8/14/2019 87444629 PPT on Sewer Design

2/16

TYPES OF FLOW Dry Weather Flow

1. Domestic waste water2. Industrial waste water

3. Waste water from u!lic facilities

". #round water infiltration

Storm Water Flow

8/14/2019 87444629 PPT on Sewer Design

3/16

Factors Affecting Dry

Weather Flow

$ate of water sul%

Poulation &rowt'

(Desi&n eriod)

T%e of area ser*ed Infiltration of &round water.

8/14/2019 87444629 PPT on Sewer Design

4/16

Factors affecting infiltrationof subsoil water into sewer

lines

Det' of sewer !elow &round water le*el

Si+e of sewerLen&t' of sewer t'rou&' infiltration rone +one

,ature and t%e of soil t'rou&' w'ic' t'e sewer is

laidT%e of -oints wor/mans'i etc.

Sewer material

8/14/2019 87444629 PPT on Sewer Design

5/16

Storm water flowT'e storm water flow deends uon t'e

followin& factors

0atc'ment area#round sloe

Permea!ilit% of &round

Etent of imer*ious areaEtent of *e&etation &rowt'

$ainfall intensit%

8/14/2019 87444629 PPT on Sewer Design

6/16

Method for estimating

storm water flow

$ational met'od

4565I5$

7ere runoff or storm water flow

4 constant

6 catc'ment area in 'ectares $ intensit% of rainfall in mm er 'our

I imermea!ilit% factor.

8/14/2019 87444629 PPT on Sewer Design

7/16

Hydraulic Design Of Sewers1) Chezys Formula:

80($S)9:.; w'ere

0 0'e+%

8/14/2019 87444629 PPT on Sewer Design

8/16

2. Mannings formula:

81=n5$9(2=3)5S9(1=2).

w'ere

n mannin&

8/14/2019 87444629 PPT on Sewer Design

9/16

3)3) HazenWilliams formulaHazenWilliams formulaBB

8:.C;575($9:.A3)5(S9:.;:).8:.C;575($9:.A3)5(S9:.;:).

w'erew'ere 7 is 7a+en William

8/14/2019 87444629 PPT on Sewer Design

10/16

Minimum Veloityof flow

@inimum or self cleansin& *elocit% is t'e minimum

*elocit% reuired to re*ent deosition ? clo&&in& of

sediments.

It deends uon t'e s'ae si+e ? secific &ra*it% of

articles.

$euired at least once in a da%.

8/14/2019 87444629 PPT on Sewer Design

11/16

Ma!imum "eloity of flow

T'e maimum *elocit%

at w'ic' no scourin&

action or a!rasion ta/es

lace is /nown as non

scourin& *elocit%

Suc' a *elocit% deends

uon t'e material used

for t'e construction of

sewers

@aterial of sewer@aterial of sewer ,on scourin&,on scourin&

*elocit%(cm=sec)*elocit%(cm=sec)

Eart' c'annelsEart' c'annels A:12:A:12:

Ordinar% !ric/linedOrdinar% !ric/lined

sewerssewers1;:2;:1;:2;:

0ement concrete sewers0ement concrete sewers 2;:3::2;:3::

0ast iron sewer ies0ast iron sewer ies 3;:";:3;:";:

8itrified tile and &la+ed8itrified tile and &la+ed

!ric/s!ric/s";:;::";:;::

8/14/2019 87444629 PPT on Sewer Design

12/16

#etangular

Horse$shoe

%$sha&e

'ara(oli

1. 0ircular Sewers

2. ,on 0ircular Sewers B

Forms of sewer

8/14/2019 87444629 PPT on Sewer Design

13/16

Signifiane of Cirular Sewers

I. 0ircular section 'as least erimeter ? ma $ for

&i*en area so it is most efficient.II. It reuires minimum uantit% of materials ma/in&

it economical too.

III. 7a*in& uniform cur*ature it re*ents t'e

ossi!ilit% of deosition.

I8. T'e% are easil% manufactured

8/14/2019 87444629 PPT on Sewer Design

14/16

Crown Corrosion

H2SO4

DropsAir

H2S

Wastewater

Cement

concrete pipes

8/14/2019 87444629 PPT on Sewer Design

15/16

Measures to overcome CrownCorrosion

1.8entilatin& t'e sewers

2.Oeratin& sewers to full run

3.Pretreatment to reduce sul'ate

".Pro'i!it entr% of sul'ides

;.Linin& t'e concrete ies !% *itrified cla% !loc/s.

A.,eutrali+ation of sul'ides !% c'emicals.

8/14/2019 87444629 PPT on Sewer Design

16/16