Power Sewerage

8/13/2019 Power Sewerage

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Drawings (2D, 3D)

• Details………..

• Arch itectura l drawing: This type of drawing gives a complete view of building. It describes thelocation of a building and where to place every parts of building etc. It holds many other drawingsheets of different names. Such as plan, elevation, section etc.

Structural drawing: Its name describes about it. It explains everything about structure such as

strength of different part of structure, structural material, placement, grade and size ofreinforcement etc. It also contains many other different named drawing sheets inside it.

• Plumbin g and sanitary drawing : This type of drawings show the location of sanitary and watersupply piping and fixture and how to connect every fixture etc.

Electr ical drawing : This kind of drawings describe the location and details of electrical wiring,fixtures and sub-station etc. It also shows the electrical load calculation.

Fin ish ing drawing: It includes all drawing about finishes and out looking of building such as tiles,marble granite etc. Sometimes this type of drawing included with architectural drawing

• Missing drawing ?????

• EW……..



Flow conditions (Refer to detail calculation)

Depth of flow Hydraulic

mean depth

Full or ½ full

bore

Diameter X

0.25

¾ depth of

flow

Diameter X

0.30

2 /3 depth of

flow

Diameter X

0.29

1/3 depth offollow

Diameter X0.19

¼ depth of

flow

Diameter X

0.15



End products



Check

• Sewage is mainly a liquid waste containing

some solids, produced by humans. It

typically consists of washing water, feces,

urine, laundry waste and other materialwhich goes down drains and toilets from

households and industry. Sewage sludge

is an end product of the wastewatertreatment process. This material can be a

wonderful source of nutrients for the soil



Hydraulic mean depth; m or R

• The hydraulic mean depth of a

liquid flowing through a pipe is

equal to the sectional area ofliquid divided by the wetted

perimeter



Sewage and population equivalent

• It can be defined as; ‘The equivalent,in terms of a fixed population, of avarying or transient population (e.g.Restaurant or Airport) based upon afigure of x xx grams/BOD/hd/day and 225 litres /hd/day .

• This means in practise that 1 person

resident in a normal house is expectedto produce 225 l of sewage flowcontaining xxx g o f BOD per day . Inother words 225 l of flow containing

xxx g of BOD is equivalent to 1Population Equivalent or 1 PE. Sotherefore a house with five peopleliving in it would have a PE of 5 andwould produce:5 x 225 l = 1125 l of flow & 5 x (xxx) g= 5xxx g of BOD .



BOD

• Biochemical oxygen demand or B.O.D is the amountof dissolved oxygen needed by aerobic biologicalorganisms in a body of water to break down organicmaterial present in a given water sample at certain

temperature over a specific time period. The BOD valueis most commonly expressed in milligrams of oxygenconsumed per litre of sample during 5 days of incubationat 20 °C and is often used as a robust surrogate of thedegree of organic pollution of water .

• BOD can be used as a gauge of the effectiveness ofwastewater treatment plants

http://en.wikipedia.org/wiki/Oxygenation_(environmental)

http://en.wikipedia.org/wiki/Water_pollution

http://en.wikipedia.org/wiki/Sewage_treatment

http://en.wikipedia.org/wiki/Sewage_treatment

http://en.wikipedia.org/wiki/Water_pollution

http://en.wikipedia.org/wiki/Oxygenation_(environmental)



Effect of gradient

• Gradient = f (v…..)



Check>>>>>V, Q

Based on the following equations,

calculate the velocity of flow (m/sec)

in a 40 cm diameter sanitary sewer

pipe flowing at a depth equal to three-

quarters of the diameter when the

gradient is 1 in 100. Also, calculatethe flow rate (m3/sec) in the pipe.

Assume the pipe were made from ast

iron or DI

(i) Manning

(ii) Hazen-William(iii) Others



Effect of steeper gradient, I

• If a gradient is too steep i.e. steeper than 1 in

40, the liquid may run faster than the solids in

the sloping foul water pipe thus leaving the

solids stranded, which could then block the pipe.

• If the gradient is not steep enough, i.e. less than

1 in 110, then the pipe could still block if the

solids slow down and become stranded.



Sewerage system



Force mains



Size



Joint



Manning etc



Embedment (continued)



Embedment (Continued)



Sewer Pipelines testing



Straightness are important to

achieve the design velocity



Hydraulic design of gravity sewers

• The hydraulic design of four sewers shall be based on a sewageproduction value of 225 litres/head/day at a peak flow factor of 4.7x p-0.11 where p is the estimated population equivalent in thousands.

• The minimum design at full flow shall be 0.8m/s to allow selfcleansing

• The determination of discharge capacity of gravity pipelines iscommonly made by using the ……whereby hydraulic resistance isexpressed by various roughness coefficient which depend on the

type material and operational conditions. Tables giving velocitiesand pipe capacities at various gradients and roughness coefficient

are commonly available.



1.PE calculation (example)

• Site A, B, C and D



3.Peak flow factor, p

• =4.7 x (PE/1000) -0.11

• =……..litre/sec



5.Selection of pipe, gradient etc



6.Self cleansing velocity

• Using Manning eq (Alternative 1, 2)

• Hazen-Willians (Next week), diff %

• Based on min hidraul, ¾ full etc



Construction

• Layout (GL, RL, SIL etc.) >>>Longitudinal section

• MH no., GL, Prop. IL, Prop depth, Prop distance

Power Sewerage

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