Environmental Issues of

ovariesracialUrban and Civil

Nov 25, 2013 (3 years and 8 months ago)

96 views

Environmental Issues of
LANDFILLS


Philosophy: To contain the waste in a
environmentally sound manner



Landfill method of Solid Waste Disposal


Landfill
Siting

considerations


Liner Systems for landfills


Leachate

Collection & Removal System


Final Cover System


Leachate

& Landfill Gas Management


Environmental Monitoring


Landfill Closure


Landfills


Landfill Types


Inert Waste Landfills



Non
-
hazardous waste or MSW Landfills



Hazardous Waste



Landfills Components


A liner system at the base and sides of
the landfill


A
leachate

collection arrangement


A cover system at the top


A gas collection system


A surface water drainage system


An environmental monitoring system


A post
-
closure plan for maintenance and
utilization of the landfill after its closure



A Typical Landfill

Life Cycle of a Landfill


Landfill Preparation


GW monitoring facilities installed first of all


Liner & leachate collection pipes laid on bottom


Waste placed on the landfill


Gas collection pipes laid on the waste


Final cover placed on the top of the landfill
for landfill closure


Starting of environmental monitoring & Post
-
closure care


Site ready for alternative use


Reactions Occurring in a Landfill

Biological, physical/chemical reactions occurring in the
landfill



Physical Reactions:


Gases diffusion, leachate movement & landfill settlement



Chemical Reactions


Dissolution, suspension, evaporation, sorption, de
-
halogenation

and decomposition of chemicals



Biological Reactions


Aerobic & anaerobic, affecting the quality & quantity of
leachate & LFG


Concerns with Landfills


Landfill Gas (LFG)


causing
odour

& other potentially dangerous substances


Impact of LFG on greenhouse effect in atmosphere


Impact of
leachate

to the GW


Slope Stability for waste and other components of the landfill


Surface water contamination


Local air contamination due to fugitive dust and bad
odour
,


Other problems such as


increase in rodents and pests;


risk of fire;


bird menace; and


blockage of surface water drainage paths



GW contamination
hazard rating



Source hazard
rating

Pathway hazard
rating

Receptor hazard
rating


Waste
quantity


Waste
composition


Infiltrating
precipitation

Waste
quantity

HW fraction

Biodegradable

C&DW fraction

Precipitation

Cover system


Vadose

zone

Containment


Aquifer
zone

Sub
-
soil /
groundwater

Groundwater
users

Landfill cover
parameters



Vadose zone
parameters

Aquifer zone
parameters

GW contamination
hazard rating



Source
hazard


Pathway


Receptor

HW fraction

Biodegradable

C&DW fraction

Landfill
contamination




Landfill
Siting

Criteria


Haul Distance


Location Restrictions


Available Land Area


Site Access


Soil Conditions & Topography


Climatological

Conditions


Surface Water Hydrology


Geologic & Hydro
-
geologic Conditions


Local Environmental Conditions


Potential Ultimate Uses for the Completed Site


Leachate Management


Leachate Recycling



Leachate Evaporation



Leachate treatment



Discharge to a wastewater treatment
plant


Precipitation
Gas
Odour
Waste
Leachate
Contaminated groundwater
Litter
Dust
Bird Menace
Contaminated
Surface water
Fire &
explosion
Fig. 1.1. Environmental Impacts of a Waste Dump
Rodents
& Pests
Vadose zone

Landfill

Aquifer zone

Source

Receptors

Direction of GW flow

Pathway

Liner

Groundwater

Ground
-

water well

Rock stratum

Leachate

Movement

Determination of
leachate

strength indicator


Leachate

strength

indicator

of

wastefill

varies

with

waste

composition

and

wastefill

depth

/

height
.


It

varies

with

time

is

considered

to

be

maximum

at

the

time

waste

placement
.

Post
-
active period

Active life

Time

Considered

Expected









t
D
i
P
S
S
c
s
a
t
pa

exp
,
LR
a
F
S
S


0
0
S
Leachate strength

Landfill

Landfill..

Landfill Gas


Generated as a product of waste
biodegradation


Aerobic Biodegradation

C
a
H
b
O
c
N
d

+(4
a + b − 2c + 3d)/4 O2


aCO2


+ (
b − 3d)/
2 H2O +
dNH3.



Anaerobic Biodegradation

C
a
H
b
O
c
N
d

+ (4a
-
b
-
2
-
3d)/4 H2O → ( 4a
-
b+2c+3d)/8 CO2






+ (4a+b
-
2c
-
3d)/8 CH4 + dNH3

Landfill gas composition

Constituent

Percent

CH4

55
-
75

CO2

25
-
45

H2S

0
-
3

N2

0
-
0.3

H2

1
-
5

O2

0.1
-
0.5

CH4 is considered as a relatively important gas as compared to the


other constituents







Landfill methane generation at its peak shortly after initial waste


placement.

Phase
I
Phase
II
Phase
III
Phase
IV
Phase
v
0
40
80
0
20
40
0.0
0.2
0.4
0.6
0.8
1.0
0
200
400
600
0
2
N
2
Gas Production
CO
2
Ch
4
O
2
COD
TVA
H
2
Fig:1 Five phases of landfill stabilisation. (Adapted from Pohland and Harper, 1986.)
Incremental Gas Production, m
3
Gas Composition, % by Volume
Stabilization Time, days
COD, g/l
TVA, g/l
I-Initial Adjustment
II-Transition Stage
III-Acid Formation
IV-Methane Fermentation
V- Maturation
LFG Management


Active & Passive Control


Vacuum is induced (Active)


Pressure built
-
up in the landfill is used (Passive)



Control of VOCs emission



Passive control e.g. Pressure Relief vent



Active Control e.g. Perimeter gas extraction
&
odour

control Wells

LFG Management


Flaring of landfill gas


Thermal Destruction in presence of oxygen



LFG energy recovery system


To produce electricity


Using combustion engine or gas turbines


Moisture & H
2
S needs to be removed



Gas purification & recovery


CO2 may be separated using physical adsorption,
chemical adsorption or by membrane
seperation
.


Environmental Monitoring


Monitoring


Vadose zone monitoring for gases & liquids


Groundwater monitoring


Air Quality Monitoring


Vadose Zone monitoring


Liquid monitoring to detect any leakage of leachate from landfill
bottom


Gas monitoring to detect movement of LFG in lateral direction


Groundwater Monitoring


To detect changes in water quality due to escape of gases &
leachate


Air Quality monitoring


Monitoring of ambient air quality


Monitoring of LFG extracted from the landfill


Monitoring of gases from gas processing facility


Landfill Closure & Post
-
closure
Care


To define what is to happen to the landfill in the
future and estimating the funds required


Long
-
term closure plan


Design of landfill cover & landscaping of completed
site


Control of run
-
off, erosion control, gas & leachate
collection & treatment and environmental monitoring


Post
-
closure care


Routine inspection of completed landfill site


Maintenance of infrastructure


Environmental monitoring


Decision on whether to continue/NOT


LANDFILL OPERATION


A

phase

consists

of

cells,

intermediate

cover,

liner

and

leachate

collection

facility,

gas

control

facility

and

final

cover

over

sub

area
.



CELL
-

Volume

of

material

placed

in

a

landfill

during

one

operation

period,

usually

one

day
.



LIFT
-

Complete

layer

of

cells

over

active

area

of

the

landfill
.



DAILY

COVER

(
15

to

30
cm)

of

soil

is

applied

to

working

faces

of

landfill

at

end

of

each

operating

period
.




INTERMEDIATE

COVERS

are

placed

at

end

of

each

phase



FINAL

COVER

LAYER

is

applied

to

entire

landfill

surface

of

phase

after

all

land
-
filling

operations

are

completed
.





ENVIRONMENTAL ISSUES



WASTE CHARACTERISTICS:
Waste from all sources
tested for composition, physical, chemical, biological,
thermal, toxic and geotechnical properties.



TRAFFIC:
Heavy lorry traffic give rise to nuisance
,
damage to road surface, verges and routing
problems.
To avoid traffic congestion, routing to residential areas
be avoided, one
-
way traffic in narrow roads,
upgradation

of road, limiting vehicle movements number
and restriction of traffic movement hours are essential.


ENVIRONMENTAL ISSUES



NOISE
-

Movement
of
heavy vehicles
, fixed and
mobile
plants. May have adverse impact on local community.
Peak noise analysis at site and nearby inhabited zone
on monthly basis to be done. Peripheral noise
abatement measures may be adopted.



DUST
-

Site
preparation and
restoration, disposal
of fine
particles and traffic. Ambient air quality monitoring
particularly PM10 on a monthly basis specifically at
noon during hot, dry and windy days is essential to
protect vegetation planted on rehabilitated landfill
surface and to meet specified standards. Dust
suppression can be effected by limiting vehicle speed,
spraying roads and fine particle waste

with water.



ENVIRONMENTAL ISSUES…



FIRES


Problems of health, air quality and social
acceptance with surrounding community. Can cause
serious damage to infrastructure of landfill and can be a
major hazard for site staffs. All fires on
-
site should be
treated as potential emergency and dealt with accordingly.
All sites should have tipping area set aside from the
immediate working area for deposition of waste materials
known to be or suspected on fire.



BIRD MENACE


Attracted by food waste. They are seen
as noisy and messy, and carriers of pathogens or cause of
local nuisance through fouling of roofs and roof
-
water
supplies. Measures to mitigate bird nuisance are good
landfill practice, small active working areas, and
progressive prompt covering of waste.



ENVIRONMENTAL ISSUES…



MUD
-

Common

causes

of

public

complaint
.

Can

result

in

accidents
.

Providing

wheel

cleaning

facilities

may

prevent

mud

carry

off

site

by

vehicles
.



GROUND

WATER

MONITORING
-

Minimum

of

three

samples

from

each

aquifer

analyzed

on

monthly

basis

for

drinking

water

quality

parameters
.






ENVIRONMENTAL ISSUES…



CONTROL OF SURFACE WATER


Minimum of 3
samples from storm water drain to be analyzed for
parameters relevant to wastewater drains on monthly
basis to quantify extent of run off contamination from
completed cell by waste materials.



CONTROL OF LEACHATE
-

It has potential to
contaminate groundwater.
Leachate

quality has to be
assessed at both laboratory and field for
leachate

treatment strategy. Effective
operational practices and
engineering controls at
landfill facility is a must.

ENVIRONMENTAL ISSUES…


LITTER


Windblown litter may be due to poor

compaction or
un
-
covered waste.

Offensive to
neighbours
. It results in water
pollution and nuisance to surrounding property. Good
operational practice in terms of waste discharge, placement,
compaction and covering minimize wind blown litter.



LANDFILL GAS MONITORING
-

LFG is a hazard at landfill
sites due to its explosive and asphyxiation risk. LFG consists
of methane, CO
2
, H
2
S and other gases. Monitoring of LFG is
essential to minimize
odour

generation, to prevent off
-
site
migration of gases and gas recovery.



SAFETY ASPECT
-

Includes site safety, first aid and handling
of waste materials. Emergency safety plans should be laid
down at landfill sites.


ENVIRONMENTAL ISSUES…



PEST AND RODENTS
-

Threat to public health. Rats
and flies are main vectors which require control. Vectors
can be controlled on the landfill by not providing sources
of food and water or shelter. This can be achieved by
applying daily cover or by spraying insecticides on
exposed faces and flanks of the tipping area.



ODOUR
-

Biodegradation of organic wastes,
leachates

and
leachate

treatment system, and landfill gas. Monthly
analysis at site and at 200m intervals from landfill
boundary to nearest inhabited zone to be done. Use of
intermediate cover layers, gas extraction system, daily
cover, adequate compaction and
leachate

management
are effective
odour

control measure.





ENVIRONMENTAL ISSUES…



MAINTENANCE OF INFRASTRUCTURES
-

Routine
maintenance such as white washing, daily cleaning and
sweeping etc. should be
carryied

out at landfill site.



MANAGEMENT OF WORKING FACE


A working face
is area where waste is deposited by trucks, leveled,
compacted and where daily cover is applied. Poor
working face management has potential to result in
blowing litter and debris, greater potential for accident,
inefficient use of air space, aesthetic problems, traffic
movement problems and vector problems.






A Proposed Landfill project


A site with a total area of 9.7 ha has been selected on
territory belonging to the village.



The site, designed for the disposal of municipal waste, is
situated about 8 Km southwest from the main town of the
region.



It will serve three municipalities.



The landfill will comprise five separate cells, which shall
be built simultaneously.



The project comprises a landfill and waste transfer station.

Landfill components


External communications and access roads, water
supply, power supply, and drainage of
leachate

to the
Wastewater Treatment Plant (WWTP);



Five cells, with a road and fence, controlled drainage, a
bottom watertight seal and drainage system for
leachate

collection;



A front area including an office, traffic
-
control building,
weigh bridge; garage with repair room and store, auto
wash, an emergency generator plant, station for
purification and burning of bio
-
gas and a WWTP


Landfill components…


wells for monitoring and controlling ground
waters (three outside the landfill and three
around the station for the purification and
burning of bio
-
gas); and



machinery and equipment, including a bulldozer
(front
-
end loader) for spreading and flattening
the loose wastes and for applying the daily soil
cover; a compactor to carry out threefold
compaction of waste; a dump
-
truck for
transporting earth and other loose materials; and
a central computer.

More details


The construction of roads comprises development of an
access road to the site, as well as a site network of service
roads to allow dumping of wastes in the different sections
on a daily basis.



Watertight sealing of the bottom of the cell shall include a
clay screen, HDPE liner and sand. Drainage for
leachate

collection is placed above.



The main dike is envisaged to surround the cells with a road
and fence. To form the five cells of the landfill, the
construction of four partition dikes is planned. The dikes
shall be made out of earth and will be faced with clay and
an HDPE liner

Other Landfill Elements


Sealing:

Sealing of the bottom of the landfill
includes the following:


controlled drainage
-

the drainage system will be
installed under the bottom liner after
levelling

the
landfill;


leachate

drainage
-

a system which shall be
constructed in order to collect and drain away storm
water from the body of the landfill storm that has
infiltrated the waste. The
leachate

shall be pumped to
the WWTP. After treatment, the water shall be
discharged into the nearby drain, which meets the
river subsequently.


Other elements…


Gas abstraction system:

For abstraction of
the bio
-
gas from the landfill a gas extraction
system shall be constructed. It will consist
of:


three gas abstraction wells

which shall be
constructed continuously and parallel with
operation of the cells and the depositing of
waste. In addition, there will be a surrounding
gas pipeline for leading the gas away from gas
wells to the gas
-
purification and burning station.


Other elements…


Fence:

The fence will be constructed to
prevent uncontrolled access of people and
cattle. The fence, made of reinforced
concrete, shall surround the site.



Daily operation
:
After completion of
works, the operation of the landfill will start
with the filling in of Cell 1. Dumped waste
shall be spread and compacted in layers of
20 to 30 cm.



Other elements…



Deposition of waste shall be conducted daily in
sections of 1.8 m in height. Sections shall be
separated with soil and crushed construction waste.
After reaching a thickness of 1.8 m, the waste layer
shall be covered by a 0.2 m layer of soil.



Deposition will continue in this way until the crest of
the surrounding and partition dikes is reached.
Afterwards, the waste body will be shaped to form a
slope with an inclination towards the dike’s crest.
Operation of the other cells shall be similar.


Other elements…


Capping layer:

After reaching the planned elevation of
the waste body in each cell, the waste shall be covered
with a capping layer. This shall include humus to allow
grass to be planted.



Waste Transfer Station:

Since two out of three
municipalities that will be served by the landfill are
located at a distance of 60 km from the landfill, a waste
transfer station for these municipalities is envisaged. It
shall be constructed on the territory of one of these
municipalities, in the area of the existing waste
depositing site.


Other elements…


The terrain selected for the waste transfer station has a total area of
0.7 ha.



The vehicles transporting municipal waste are brought up through a
ramp in the transfer station.



They unload the solid municipal waste at a site located over the
press.



The waste is dumped into the press funnel and is pressed directly
into the containers.



Special vehicles transport the filled containers to the landfill for three
municipalities. A weighbridge shall be installed next to the office of
the transfer station.



Identify key environmental issues
associated with the proposed
landfill project?

Thank You!