lecture to be civil & urban

8/8/2019 Lecture to BE Civil & Urban

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Technical Lecture

toFinal Year Bachelor of Civil and Urban Engineering

Department of Environmental Engineering

An Introduction to Sanitary Landfill

- A Viable Solution for

Existing Solid Waste Management

Practices in Karachi Metropolis

Dr. Mansoor Imam

Associate Professor, Department of Civil Engineering,

NED University of Engineering and Technology, Karachi


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Solid Waste Management (SWM)System

Community Based

Organisations CBOs

and other operators

(private contractors,

sweepers etc)

CollectionD

TransportationD

DisposalHierarchy of Solid Waste Management

Town

Councils

Union

Councils

Collect & Transport waste from

designated locations to disposal

sites

Collect & transfer waste from

community bins to designated

locations within the Town

jurisdiction

Formal

Informal

Collect from

streets/houses/public places

and transfer to Community

Bins Kachra Kundis

Recovery

&

Recycling

Recovery

&

Recycling

Recovery

&

Recycling

Recovery

&

Recycling

Recovery

&

Recycling


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Solid Waste Management by Informal Sector

Recovery of recyclable material from waste at various levels

Household Kabadis

Level Operator Activity

Door-to-door collection of

recyclable items; Paper,

Glass, Metal, Plastic, etc.

Street Scavengers or

waste pickersWandering in the streets and

hand-picking recyclable items Community bin

Disposal site Potters,

Contractors,

etc.

Rich organic waste is

burnt as fuel forkilns,

and metal recovery.

Dried waste forfills

Waste Recovery = 12%

Waste Recovery = 11%


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Separated at household and sold toKabadis 800 tons/day

Collected by waste pickers or scavengers 700 tons/day

Waste utilisation prior to final Disposal 750 tons/day

Estimates of Solid Waste Managed (Pre-Devolution) by

Formal and Informal Sector

Formal Sector

Managed by Metropolitan services 2,200 tons/day

Informal Sector

Unmanaged / uncollected Solid Waste 2,150 tons/day

Total Estimated Solid Waste generated 6,600 tons/day

33%

33%

33%

Source: Urban Resource Centre


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Changing Perspectives ofChanging Perspectives ofSolid Waste ManagementSolid Waste Management

Approx. 50,000 tons of solid waste is generated per day in Pakistan

~20,000 tons arises from Urban areas

~30,000 tons from Rural areas Source: NCS

Present coverage of Urban Solid Waste Management is 25%

and then to 90% by 2025

shall increase to 55% by 2010-11

US$ 25 million has been allocated for the improvement ofSWM System

Environmental Strategy 2002: IUCN


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Safe Disposal of Solid Waste most critical aspect of SWM

Open Dumping sitesUncontrolled tipping

Informal

Drains / Nalas

Empty Plots

Natural Depressions

Formal

Reclamation of land

Sanitary Landfill or Open Dumping ???

Concept ofSanitary Landfill is virtually non-existing

Sanitary Landfill sites are open dumping grounds

Jam Chakro (500 acres) Gond Pass (500 acres)

1000 tons/day 500 tons/day

Dhabeji (remote site) non operational


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Introduction to Sanitary Landfill

Landfillan engineered facility developed on a designated piece ofland that principally receives waste as a fillover a period of time until

the designated area is fully utilised. The development and operation at

the facility is usually costeffective while maintaining appropriate health,

safety andenvironmental standards.

Landfill Methods

Excavated cell or trench method Area method

Canyon or depression method

Selection of method depends upon:

Geographical features

Geohydrological characteristics

Economic constraints; Operational limitations; Post-closure use; etc.


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Development of Landfill Facility

Selection of site for Landfill

When selecting a site for landfill, following considerations are made:

Haul distance

Location restrictions

Available land area

Site accessibility

Soil conditions and Topography

Climatologic conditions

Surface water hydrology

Geologic and Geohydrologic conditions

Environmental impact of landfill site

Potential post closure use


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Establishing Design Criteria

Waste characteristics &

Quantity Operational & Design lifeD

Infiltration

Surface Water drainage

Disposal of Leachate

Production ofGas

Daily Cover design (material)

Final Cover Liner system

Leachate management system

Gas Collection & Recovery system

D

Post closure Monitoring (Leachate and Gas)

Future use and development

Facilities Development Infrastructure, Utilities & ServicesD

D


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Collection of Necessary Data for Design of Landfill

Hydrogeologic investigation

Geologic Stratigraphy

Groundwater depths and flow directions

Soil investigation Characteristics of local soil(s)

Topography and Contour mapping

Climatologic data Precipitation, Temperature,Humidity, Wind pattern, etc.

Physical data of site layout, boundary demarcation and vicinity land-use

Geotechnical investigation


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Typical components of a Sanitary Landfill

Liner system (A)

Cap system (B)

Gas management system (C)

Leachate management system (D)

Erosion & Sedimentation control

Surface water management (E)

Monitoring system (F)


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6 Topsoil

ayer

24"

arrier

rotection

ayer

Geomembrane

18"

lay

ayer

12" Gas Venting

ayer

Solid Waste(variousthickness)

24"

rimary

eachate

ollection

emoval System

Geomembrane

6"

lay

ayer or G

12" Structural

ill

12" Secondary

eachate

ollection System

Geomembrane

24"

lay 24 thick lay layer

12 thick pervious layer Secondary eachate collection

12 thick Structural fill compacted for stability

24 thick pervious layer rimary eachate collection

Solid waste

compacted in layers

(cell lift)

12 thick Gas Venting layer

Geomembrane

Geomembrane

18 thick lay layer

24 thick arrier protection layer

6 thick Topsoil layer

Geomembrane

overSystem

Waste mass

inerSystem

Typical section of a

Sanitary Landfill


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Preparation of Design Document

Design and Plans for Landfill Operations

Revision of plans according to the progress of work

Plans & specifications for Landfill system components

Preparation of Development,

Operations & Maintenance

plan

Infrastructure Development at Landfill site


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Conclusions and Recommendations

A properSanitary Landfill is the only option forsafe disposal ofsolid waste generated in Karachi Metropolis and must be developed

on priority basis.

Though the available waste management infrastructure is inadequate

to support and sustain proper sanitary landfill facility, howeverinvolvement

of private sector may provide a sustainable solution.

It would be appropriate to have more than one easily manageable

landfill sites located in vicinity of urban settlements rather than one

large facility remotely situated.

Integration of informal sector within the formal sector may

improve, managing waste efficiently. The active role of informal sector

in managing the waste should therefore, be recognised and promoted by

the civic administration.

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