Introduction to Sewerage Network Design

Presented by Mazhar Alam

Basic Definitions

• Sewage

• Sewer

• Sewerage

Basic Definitions

Sewage It is mainly liquid waste containing some

solids produced by humans and industry. Foul water , waste water.Grey water-Non faecal. From washingBlack water-Contains faecal matter. It needs full treatment.

Basic Definitions

SewerAn artificial conduit (or pipe) or system of conduits used to convey sewage from source to sewage treatment facility.

Basic Definitions

SewerageThe system of sewers that conveys wastewater (sewage) to a treatment plant or disposal point.

It includes all the chambers, manholes, gravity mains, pumps, rising mains, air valves, washouts etc

Design of Sewerage NetworkInformation Required•Design Criteria

•Master Plan Layout Drawing

•Levels

Design of Sewerage NetworkDesign CriteriaIt describes the parameters to be used in design;•Sewage generated per person•Minimum, maximum & proportional velocity•Minimum slopes•Peaking factors•Pipe diameters and material etc•Minimum Backdrop height.

Design of Sewerage NetworkSewage generated per personIt depends on the type of occupancy or land use details of the facility to be served. e.g. residential, commercial, recreational.

Qasr Al Sarab sewage generated from villas - 275 l/p/d

Hotels – 298 l/p/d

Design of Sewerage NetworkMin. , Max., Proportional velocityMin. velocity is normally 0.75m/s at full capacity to allow for self cleaning.

Max. velocity is 2.5 to 3.0m/s.

Proportional velocity is the actual velocity at given flow. 0.6m/s

Design of Sewerage NetworkMinimum slopesFor a given diameter and roughness minimum slope is required to achieve min. velocity.

Dependent on the pipe diameter and roughness e.g. for dia=200 and k=0.6 the minimum slope is 1:240.

For lager dias the minimum slope is 1:1000

Design of Sewerage NetworkPeaking FactorBabbitt A/(P)^B ( A=0.176,B=5.096)

Abu Dhabi (18+sqrt(P))/(4+sqrt(P))

Harman 1+(14/(4+sqrt(P))

Design of Sewerage NetworkPipe dias & materialIn the UAE

Minimum pipe dia is 200mm for main line and

150mm for house connection pipe.

Material;

uPVC – for smaller dias

GRP – for larger dias

Design of Sewerage NetworkMinimum backdrop height•Avoid direct fall

•Splashing

•Erosion of benching

•Smooth transition

•Minimum value. 600mm to 700mm

Design of Sewerage NetworkMaster Plan Layout Drawing•Plot – types and land use details

•Road corridor – ROW for services

•Location of STP or final disposal point

Design of Sewerage Network Levels•Spot Levels

•Contours

•Finished Road Levels

Design of Sewerage NetworkSteps in design

• Marking the network on layout.

• Calculating the population

• Hydraulic design

• Final presentation drawings.

Design of Sewerage NetworkSteps in design

Marking the network on layout.• Gravitating the network• House connection chambers- at each plot• Manholes- maximum spacing• Angle b/w incoming & outgoing sewer.• Max. no. of connections to a manhole.

Design of Sewerage NetworkSteps in design

Population calculations.• Type of plot single storey or multi rise.• Type of occupancy i.e. villa, hotel, office,

school, restaurant etc.• Equivalent population.

Design of Sewerage NetworkSteps in design

Hydraulic design.

• Spread sheet - Excel

• Software – WinDes, PipeMate, Sewer CAD.

Design of Sewerage NetworkSteps in design

Final presentation drawings.

To show pipe dias, invert level, cover levels, manhole types etc.

• Manhole schedule

• Layout drawings

LINE DIAGRAM- SEWAGE NETROWK

Phase III• Commissioned in 1993• The Works provided an additional capacity of 25700 m3/d

• Client : • Sharjah Municipality Drainage Section (SMDS)

• Civil Contractor: • Six Construct

• PM /M&E RE :

• Consultant :

• M&E Contractor: • PCL

• Halcrow

• Martin Davis• Civil RE : • Stephen Smythe

LINE DIAGRAM- SEWAGE NETROWK

3D VIEW - WINDES

3D VIEW - WINDES

MANHOLE SCHEDULE – WINDES OUTPUT

LOND SECTION - WINDES

Questions