Preliminary design and operation of sanitary landfill

Prof. M.R.Ezhilkumar
Assistant Professor
Department of Civil Engineering
Sri Krishna College of Engineering and Technology
Coimbatore
ezhilkumar@skcet.ac.in
I only feel angry when I see waste.
When I see people throwing away
things we could use. – Mother
Teresa
1
17CE413
SOLID AND HAZARDOUS
WASTE MANAGEMENT
3.4 – Landfill: Design and Operation

SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 2
Learning Outcomes
☼ Landfill design
☼ Landfill operations
3.4 – Landfill: Design and Operation

Video Session

Landfill Design & Operation

Cell Construction
 All solid wastes received are spread and compacted in cells or layers within a
confined area.
 Cell: compacted wastes and daily cover material (3 m high)
 Cell: rectangular in surface area, its sides sloped as steeply as practical
operation will permit. Optimum: 10%, up to 30%
 Solid wastes are spread in layers not greater than 60 cm thick

Cell Construction
 Lift: a series of adjoining cells, all same height (3~5 m)
 Orderly operations: maintain a narrow working face
 Cover material: function of surface of wastes to be covered, thickness of the
soil needed to perform the particular functions, and cell configuration

Filling Plan for Single-Lift Landfill

Filling Plan for a Multilift Landfill

Example Landfill Plan View

Waste Decomposition in Landfills
 Physical: breakdown or movement of the refuse components by physical
degradation and by the rinsing and flushing action of water movement
 Chemical: hydrolysis, dissolution/ precipitation, sorption/desorption, and ion
exchange of refuse components; generally results in altered characteristics and
greater mobility of refuse components ® more chemically uniform.
 Biological: most important process; occurs with naturally present bacteria
 Byproducts of MSW decomposition: Decomposed solid wastes, new
biomass, generated gases, contaminants into solution (leachate), and heat.

Stabilization Phases – Phase I: Initial Adjustment
 Initial waste placement
 Preliminary moisture accumulation
 Initial subsidence
 Closure of landfill area

Stabilization Phases – Phase II: Transition
 Field capacity exceeded
 Leachate formed
 Electron acceptor shifts from oxygen to nitrates to sulfates
 Trend toward reducing conditions
 Volatile acids appear

Stabilization Phases – Phase III: Acid Formation
 Volatile fatty acids predominate in leachate
 pH declines
 Substrate conversion occurs

Stabilization Phases – Phase IV: Methane Fermentation
 Methane and carbon dioxide production
 pH at minimum
 Nutrient consumption
 Precipitation of metals
 Leachate BOD/COD declines

Stabilization Phases – Phase V: Final Maturation
 Biological dormancy
 Nutrients limiting
 Gas production ceases
 Oxygen slowly reappears
 Humic substances produced

SOLID WASTE LANDFILL DESIGN – TASKS
 Determine solid waste quantities and characteristics
• Existing
• Projected
 Compile existing and generate new site information
 Perform boundary and topographic survey
• Prepare base map of existing condition on - site and near - site
• Property boundaries
• Topography and slopes • Surface water • Utilities
• Roads • Structure • Land use

 Compile hydrological information and prepare location map
 Soils (depth, texture, structure, bulk density, porosity, permeability,
moisture, ease of excavation, stability, pH, and cation exchange capacity)
 Bedrock (depth, type, presence of fractures, location of surface outcrops)
 Groundwater (average depth, seasonal fluctuations, hydraulic gradient and
direction of flow, rate of flow, quality, uses)

 Compile climatological data
• Precipitation • Evaporation • Temperature
• No. of freezing days • Wind direction
 Identify regulations (Federal, State, and local) and design standards
• Loading rates • Frequency of cover
• Distances to residences, roads, and surface water
• Monitoring • Roads
• Building codes • Contents of application for permit

 Design filling area
 Site topography and slopes
 Site soils
 Site bedrock
 Site groundwater

Landfill Design and Layout
 Sizing your landfill
 Equations for volume

 Example:
 The foot print area of a landfill is 1000 ft by 750 ft. The anticipated depth is 30
ft. What is the volume in yd3?
 Volume = 1,000 ft x 750 ft x 30 ft
 Volume = 22,500,000 ft3
 Volume = 833,000 yd3

 This analysis did not consider side slope
 How are the side slopes described at a landfill?

 Note: Slopes are sometimes referred to in %, which would correspond to
 In the case of the previous example, a 3:1 slope would be expressed as 33%.
A 4:1 slope would be 25%.
 More common when describing shallow slopes

 How do you factor side slopes into volume formula?

 Landfill capacity refers to the time that the landfill can receive waste at a given
waste filling rate

 Example: For the previous landfill volume of 660,000 yd3, what would be the
capacity (years) of the landfill if C&D debris waste accepted at 500 tons per
day and the landfill debris density was 1500 pcy?

 Specify design dimensions
 Trench width, depth, length
 Cell configuration
 Trench spacing
 Fill depth
 Interim cover soil thickness
 Final cover soil thickness

 Specify operational features
 Use of cover soil
 Method of cover application
 Need for imported soil
 Equipment requirements
 Personnel requirements

 Design facilities
• leachate controls • Gas controls
• Surface water controls • Access roads
• Special working areas • Structures
• Utilities • Fencing
• Lighting • Washracks
• Monitoring wells • Landscaping

 Prepare design package
 Develop preliminary site plan of fill areas
 Develop landfill contour plans
 Excavation plans - including benches
 Sequential fill plans
 Completed fill plans
 Fire, litter, vector, odor and noise controls
 Compute solid waste storage volume, Soil requirement volumes, and site life

 Develop final site plan showing :
Normal fill areas Special working areas
Leachate controls Gas controls
Surface water controls Access Roads
Structures Utilities
Fencing Lighting
Washracks Monitoring wells
Landscaping

 Prepare elevation plans with cross - sections of :
Excavated fill
Completed fill
Phased development of fill at interim points
 Prepare construction details
• Leachate controls • Gas controls
• Surface water controls • Access Roads
• Structures • Monitoring wells

 Prepare ultimate land use plan
 Prepare cost estimate
 Prepare design report
 Submit application and obtain required permits
 Prepare operator’s manual

Industrial vs MSW Lfs
 Few differences in design requirements
 clay liner & cap, no gas extraction
 Industrial Lfs usually are simpler in design
 Owners are usually large plants generating large waste volumes
 Papermills, coal-burning utilities, foundries
 Some specialized features, mostly with papermill sludge landfills
 Industrial owners are making major efforts to recycle or reduce most of waste
stream

Facilities at a Landfill Site
 Entrance Facilities including Weighing Scales
 Administrative & Laboratory spaces
 Waste Inspection and Sampling Facilities
 Temporary Waste Storage
 Stockpiling for Cover Materials
 Location of Landfill Leachate Management Facilities
 Location of Gas Management Facilities

Facilities at a Landfill Site
 Monitoring Wells
 Fencing and Green Belts
 Access Roads
 Equipment Shelters
 Exit and Emergency Exit facilities

Landfill operations
 Minimize open area, reach final grades as soon as possible
 Daily, alternate, intermediate cover
 alternate cover - foundry sand, geotextiles, etc.
 daily cover not req’d for industrial waste Lfs
 Initial waste placement to protect liner from damage by traffic & exposure - min
of 4 ft
 Remove leachate continuously - treat at STP
 Prohibited & banned items & special wastes
 Restrictions in local agreements

Site Operations
 Noise control
 Use of trees and berms to attenuate noise
 Proper phasing of operations to create a buffer zone or barrier between the
source and nearby residents
 Appropriate equipment maintenance
 Regulation of hours of operation to reflect adjacent land uses
 Maximize the separation distance between the active site face and residents

Site Operations
 Odor control
 Normally a seasonal problem; sources - putrescible wastes, carcasses, sludges,
landfill gas, sulfides and mercaptans, and leachate seeps
 Immediate covering, masking chemicals, a horizontal gas collection system,
proper venting and flaring of landfill gas, collection or prevention of leachate
escape

Site Operations
 Litter control measures
 Cover open loads
 Move operations to protected areas during windy conditions, plant some
windbreaks, or operate the working face so that it is opposite to the direction of
prevailing winds. Alternatively use movable fencing
 Litter control
 Unacceptable appearance, a food source for vermin, blight, and fires
 Caused by open loads, windy-day operation, operational techniques, and
dumping practices

Site Operations
 Litter control measures
 Unload solid wastes at the bottom of the slope and push materials up the slope
 Compact and cover the refuse more frequently during the day
 Confine the dumping area to a minimal surface area
 Collect the litter on an ongoing basis

Trash Containment System
 Should not tip over and release trash
during high wind conditions (50% wind
resistance at 70 mph)
 Reduce trash retrieving labor cost
 Easy to relocate on site

Site Operations
 Dust control
 Consider using all-weather roads with proper maintenance
 On dirt road, apply calcium chloride at 0.2~0.4 kg/m2 (0.4~0.8 lb/yd2); apply
water from trucks as necessary
 Limit earthmoving activities
 Use vegetation and windbreaks

Site Operations
 Bird control
 Danger to aircraft and contamination of surface water
 Use elevated wires and/or string netting over a fill
 Rodent control
 Difficult to eliminate; must be total elimination
 Eliminate food

Site Operations
 Insect control
 Flies and mosquitoes
 Cover the solid waste and exterminate

Operation Plan
 Compactor operations:- dictates cell construction, operator determines type of cell
constructed, where and when the cell is ready for finishing and covering
 Optimum density:- space saving, point of diminishing return, high capital and
operation cost of compactor, cost/benefit

Monitoring
 Leachate head within landfill
 leakage through landfill liner (groundwater)
 ambient air quality
 gas
 leachate quality
 stability of final cover

Ground water Monitoring
Based upon:
 Site-specific field collected measurements, sampling, and analysis of physical,
chemical and biological processes affecting contaminant fate and transport,
and
 Contaminant fate and transport predictions that maximize contaminant
migration and consider impacts on human health and environment

Minimum Groundwater Monitoring
 One line of three (minimum) well down gradient from landfill perpendicular to
groundwater flow, penetrating entire saturated thickness of aquifer (1/250 ft of lf
frontage at boundary of site or at surface water
 One well immediately adjacent to down gradient edge of filled area at point where
leachate plume meets GW. Screened to intercept water table
 One well in area up-gradient from landfill

Monitoring Wells

Air Monitoring
 Explosive gases control: Methane is explosive when present in a range of 5
(lower explosive limit, LEL) to 15 (upper explosive limit, UEL) percent by
volume in air. Methane is not explosive when present in concentrations greater
than 15% however, fire and asphyxiation are still a threat at these levels.

Type and frequency of monitoring
 Determined based on the following factors:
 soil conditions;
 the hydro-geologic conditions surrounding the facility;
 the hydraulic conditions surrounding the facility; and
 the location of facility structures and property boundaries.
 The minimum frequency of monitoring shall be quarterly.

Closure
 Describe closure methods
 Address final use
 financial assurance criteria
 estimate cost of closure/post closure care
 demonstrate financial assurance
 cash
 irrevocable letter of credit
 trust funds with licensed trust company or state
 surety bonds

Post closure
 30 years
 maintain integrity of cover
 maintain LCS
 monitor GW
 maintain gas monitoring system

Assessment Time
Review
Question Recommend a suitable landfill method for Coimbatore region
based on the composition of waste generated in the city.

Preliminary design and operation of sanitary landfill

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