DW and SWS Presentation

8/2/2019 DW and SWS Presentation

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10/07/2008Slide Number- 1 of 8

Delivering excellence through people

Presentation on Drinking

Water Supply System andSanitary Disposal system


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Short presentation title10/07/2008

Slide Number - 2 of 8Engineers India LtdDelivering excellence through people

DRINKING WATERSUPPLY SYSTEM


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CODES AND STANDARDS

IS : 2065 Code of practice for watersupply in buildings.

Manual on Water Supply and Treatment - byMinistry of Urban Development


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METHODOLOGY OF EXECUTION

COLLECT POPULATION DATA

COLLECT DATA FOR TYPES OF CONSUMERS VIZ.

DOMESTIC, INDUSTRIAL, ETC.

COLLECT WATER REQUIREMENT FOR HORTICULTURE

FROM OWNER/AUTHORITIES

INTERACT WITH OWNER FOR QUANTITY AND DURATIONOF SUPPLY ETC.

WORK OUT WATER DEMAND FOR VARIOUS TYPES OFCONSUMERS


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WATER REQUIREMENT

Water Requirement shall be calculated on thefollowing basis:

Plant Service : 135 litres/capita/day Township : 450 litres/capita/day


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WATER SOURCE

The source of water for drinking water supply shall be carefully

explored by considering various alternatives available.Following alternatives may be considered. a. Tube well b. Canal/river water c. Municipal water supply

d. Plant raw/service water system e. Any other source available.

The water available from various sources shall be tested forquality and necessary treatment facility shall be studied before

arriving at the final decisions regarding selection of the sourceof supply. The water to be used for drinking shall be firsttreated, if required, to achieve the acceptable limits of waterquality


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OVERHEAD STORAGE

The capacity of overhead storage reservoir shall beat least for 6 hour requirement.

The overhead tank shall preferably have twoindependent compartments to facilitate maintenance

and clearing. The staging height for the overhead storage shall be

kept at least 20 metres. This shall be furtherreviewed to ensure a residual pressure of 0.5 kg/cm2

at the remotest tap or fixture inlet including the rooftank.


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WATER DISTRIBUTION SYSTEM

The drinking water distribution system shall consist ofunderground piping network laid along the road sideor other convenient locations. The line sizing shall bedone using PIPENET software.

Preferably be laid in closed loops and isolation valvesshall be provided at junctions.

The pipe shall be laid with a clear cover of 600mm.At road crossing a clear cover of 1200mm shall be

ensured over the pipe. In case it is not possible toprovide the required cover under the road, the pipeshall pass through a sleeve.


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WATER DISTRIBUTION SYSTEM

The Drinking Water shall be chlorinated beforedistribution. The Specification for chlorination systemshall be obtained from Environment Department.


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DW PUMPS

Drinking Water FEED PUMPS are provided to fill theOHT. The capacity of DW pumps is generally fixedthat the OHT gets filled up in 2 hours time.

Pump head shall be calculated considering theFriction Loss, Static Loss and residual pressurerequirement.


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Slide Number - 11 of 8

Engineers India LtdDelivering excellence through people

MATERIAL SPECIFICATION

Pipes (up to 150mm N.B.)

G. I. conforming to IS:1239, heavy grade (Class J2A).

Valves

-C. I. gate valves conforming to IS:780.

-Gun metal valves conforming to IS:778


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REFERENCE DOCUMENTS

8-16-47-0027 Standard Guide for DrinkingWater Supply System

16-47-DM-0006 Design Manual for DrinkingWater Supply System

8-65-0069 Standard P&ID for Drinking

Water System


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SANITARY WASTECOLLECTION AND

DISPOSAL SYSTEM


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INTRODUCTION

Sanitary waste from toilet facilities of plants and non-plant

buildings are carried through closed conduits under thecondition of gravity flow (under certain conditions: pressureflow). This waste is a mixture of water and waste products,known as sewage and the closed conduit is called sanitarysewer. The sewage is conveyed to the Waste Water

Treatment Plant where it is given suitable treatment or to septictanks/ soak pits or up-flow filter as per site conditions.

Wastes like Acidic, caustics, hydrocarbons, rain water or otherchemical waste shall not be discharge to the sanitary sewer.

In case where it is not possible to provide sanitary sewer

system due to undulation of ground profile, economic reasonsor non availability of treatment plant, local treatment is given byproviding septic tank and soak pit or up-flow filter.


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INTRODUCTION

A sewerage system consists of a network of sewer pipes laid in

order to carry the sewage from individual buildings to thesewage treatment plant. This network of sewers consists oflateral sewers, branch sewers (or sub mains); main sewers etc.Manholes are provided at suitable intervals, so as to facilitatetheir cleaning and inspection.

The sewers must be of adequate size so as to avoid their

overflow and subsequent damages to properties and health. Inorder to provide economically adequate sized sewers, the likelysewage discharge shall be estimated correctly. The sewerpipes should then be designed to be laid on a slope that willpermit reasonable velocity of flow. Thus flow velocity shouldneither be too large so as to require heavy excavations and

high lift pumping, nor should be too small to cause thedeposition of solids in the sewer pipes.


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Hydraulic Design of Sewers (Flow Under Gravity)

For flow under gravity (open channel flow) Mannings formula is

used for calculating the velocity:

V= (1/n) x R2/3 x s1/2

where R=A/P,V= Velocity in m/s,

n= Mannings Coefficient,

R= Hydraulic Radius in m,

A= wetted area in m2,

P= wetted perimeter in m,

S= Slope in m/m .


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Estimation Of Design Sewage Discharge

Generally 90% of water supply may be expected toreach sewer system.

The average daily consumption may be taken as 135lit per capita for plant area.

Average daily sewage discharge=Qs =0.9 X Av. daily water consumption

=0.9 X N X 135 /1000 Cum/day

Sewers shall be designed to a capacity of 3 times the

average daily flow.

Hence, Design Flow (Qd)=3x Avg. daily discharge

B i P t F D i Of S


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Basic Parameters For Design Of Sewer

Velocity limits

Minimum velocity = 0.75 m/s at design peak flow Maximum velocity = 2.40 m/s at design peak flow,

Provision for ventilation at ultimate Peak Flow, Pipes running Half full up to a diameter of 400mm of sewer 2/3 full for diameter more than 400 mm and upto 900 mm 3/4 full for diameter above 900 MM.

Minimum size of pipeFor one Toilet block= 150 mmFor two or more Toilet blocks= 250mm

Mannings Coefficient

Salt glazed stone ware pipe 0.012 Cement concrete pipe 0.013 CI pipe 0.012 Asbestos Cement pipe 0.011


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Manholes

Manholes shall be provided at start of sewer, junction ofsewers, change of direction, change of gradient or invert levelof sewer, change of size of sewers. Apart from abovemanholes shall be provided on straight runs at followingspacing:

Diameter of Pipe Manhole Spacing (straight Run)Dia 300 mm 30 m

300


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Material for sanitary sewers

From toilet block up to Inspection chamber

- Heavy Cast Iron (IS:1729)

Sewer Pipe from first Manhole

- Conc. Pipe (IS:458) class P1 Pressure Pipe

- Centrifugally Cast (Spun) Pipe (IS:1536).

Pumps For Lifting Sewage


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Pumps For Lifting Sewage

Introduction

Sometimes sewage is required to be lifted from a lower level tohigher level at certain place in sewerage system.Sewage may have to be lifted by pumps under the followingcircumstances:

When the laying of sewers at their designed gradients may involvedeeper and deeper excavation in the forward direction of flow. Insuch circumstances, it may be economically not feasible to laythe pipe, It is advisable to lift the sewage and then to lay sewer atreasonable depth below the FGL.

When the outfall sewer is lower than the level of the treatmentplant, the sewage will have to be pumped up.

Where water table is high, it is advisable not to lay the pipe in sub-soil water.

In hard rock areas, where the excavation for laying of sewerbecomes difficult.


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SEPTIC TANK

Septic Tanks : Its Requirement And OperationSeptic Tank are generally provided due to the following reasons:-i) When disposal of sewage produced from isolated plants and non plants buildingscannot be economically connected to main sewers.ii) When ground profile of the plant area is a hindrance for flow under gravity.

A septic tank may be defined as primary sedimentation tank (Horizontal continuous flowtype) with a longer detention period ( 12 to 36 hours), and with extra provision for digestion ofthe settled sludge. The septic tank unit works on the principle of anaerobic decomposition.Due to anaerobic decomposition of settled sludge, foul gases will be evolved in the tank, andas such, a septic tank will be a completely covered tank, provided with high vent shaft forescape of gases.

It removes about 60 to 70% of the dissolved matter from it. The effluent from such a tank willbe sufficiently foul in nature, and will have to be disposed off to soak pit.

The sludge settled at the bottom of tank, and the oils and greasy matter rising to the top

surface of sewage as scum, are allowed to remain in the tank for a period of several months,during which they are decomposed by the anaerobic bacteria to form gases and liquids bythe process called sludge digestion. The resultant sludge so obtained, will consequently bemuch less. The digested sludge from the tank is periodically (at an interval of 6 to 12months) removed.

SOAK PIT


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SOAK PIT

A soak pit is a circular pit filled with brick bats,through which the effluent is allowed to be soaked orabsorbed into the surrounding soil.

FLOW ANAEROBIC FILTER


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FLOW ANAEROBIC FILTER

The up-flow filter can be successfully used for secondary treatment of

septic tank effluent in areas where dense soil conditions, high watertable and limited availability of land preclude soil absorption or theleaching system for effluent disposal. It is a submerged filter withstone media and the septic tank effluent is introduced from thebottom. The microbial growth is retained on the stone media makingpossible higher loading rates and efficient digestion. The capacity of

the unit is 0.04 to 0.05m3 per capita or 1/3 or 1/2 the liquid capacity ofthe septic tank it serves. BOD removals of 70% can be expected. Theeffluent is clear and free from odour. This unit has several advantagesviz. (a) high degree of stabilization; (b) little sludge production; (c) lowcapital and operating cost; and (d) low loss of head in the filter (10 to15 cms) in normal operation. The up-flow anaerobic filter can either

be a separate unit or constructed as an extended part of septic tanks.


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REFERENCE DOCUMENTS

8-16-47-0036 Standard Guide for

SANITARY SEWER SYSTEM

16-47-DM-0002 Design Manual forSANITARY SEWER SYSTEM


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DW and SWS Presentation

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