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Case study - impact assessment of
proposed landfill site extension
Nigel Gibson
Case study - impact assessment of
proposed landfill site extension
Objectives of this case study are to
Illustrate the used of:
– Complaints data
– Olfactometric measurement
– Emission factors
– Dispersion modelling
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Background
The company operates an existing landfill site
(site 1) taking non-inert waste from London
Boroughs and Surrey. The infilling activities
revolve around an old sand/gravel pit on the
Thames flood plan.
Site 1 is permitted to accept waste until august
2002 but pre-settlement levels are likely to be
achieved before this time.
Proposed situation (1)
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An adjoining sand/gravel pit (site 2) is being
worked out.
The original planning permission for site 2
allows for landfilling of inert waste.
The Company submits a planning application:
to re-excavate under a portion of site 1 to retrieve
sand/gravel under 15 year old waste deposits. The
excavated waste is to be used to re-contour a
portion of site 1
to landfill the excavated portion of site 1 and site
2 with non-inert waste in two phases
2
Proposed situation (2)
Proposed situation (3)
Planning permission is refused on the
grounds of:
“The development by virtue of its proximity to
residential properties would give rise to
occasional and unacceptable harm to the
quality of life of the occupiers of those
properties and amenities of the locality and
would therefore be contrary to ……”
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Complaints from site 1
NQ
NO
NM
U
S
Å ç ã é ä~ áå í ë
Q
k çî
pÉé
j ~ó
j ~ê
g~ å
M
g ì ä=
O
Other sources in area
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Approach taken by operator
attribute most odour complaints to other
sources in area
measure odour emissions on site
predict concentrations using dispersion
modelling
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Test work undertaken (operator)
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Site boundary assessment
Odour sampling undertaken on:
tipping operation
tipping area
temporary covered area
excavation trial pits
Odour impact assessment
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Complaints attributed to compost
plant
Sampling methods employed
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Hood method for surface sources
Micrometeorological method for surface
sources
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plume
Micromet
mast
3 sample
collection
points on mast
Excavation trial pit
Emission rate ∝ conc. Distribution on mast and fetch
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Results summary (operator)
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Waste unloading - 55 ou.m-2S-1
Working area 8.7 ou.m-2S-1
Covered area (soil) 0.7 to 0.9 ou.m-2S-1
Covered area (plastic) 0.5 to 0.6 ou.m-2S-1
Excavated waste (pit) 1,300 ou.m-2S-1
Excavated waste (deposited) 3 ou.m-2S-1
Impact assessment
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Measured emission estimates used in
dispersion modelling exercise (AERMOD).
All sources treated as large area sources with
an emission rate = sources area * emission
estimate
odour assessment criteria of:
!
5 ou/m3 as a 98th%ile (from Newbiggin)
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Current situation-1 (operator)
Current situation-2 (operator)
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Future situation-2
Approach taken on behalf of planning
authority (AEAT)
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Assigning realistic average odour
emission factors to the various sources
on site using measured data from
assessments undertaken on other noninert landfill site.
Considers situations that could
‘reasonably be expected to occur’
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Summary of data used by AEAT
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Tipping of Fresh waste 25 ou.m-2S-1
Operational area 1.5 ou.m-2S-1
Impact assessment
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Measured emission estimates used in
dispersion modelling exercise (ADMS 3).
All sources treated as large area sources with
an emission rate = sources area * emission
estimate
odour assessment criteria of:
3 ou/m3 as a 98th%ile (from Brogborough
landfill site assessment)
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Current situation (AEAT)
Future situation (AEAT)
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Data for future (operator)
Phase A - Odour emission characteristics
emission rate
(ou/m 2/s)
Area (m 2) Day
Modelled
Unloading – WTS 25
34.2
Unloading –bin
25
7.06
Deposited material 1375
8.7
Temp cover(soil)
9795
0.91
Temp
12191
0.55
cover(soil+plastic)
Total
23411
Total (tipping area) 1425
total emission (ou/s)
night
Day
Night
0.91
0.91
0.91
0.91
0.55
855
177
11963
8913
6705
23
23
1251
8913
6705
28613
12994
16915
1297
Data for future (AEAT)
Phase A - Odour emission characteristics
emission rate
(ou/m2/s)
Area (m2) Day
Night
Modelled
Tipping area 1500
25
1.5
Temp cover 17825
1.5
1.5
Total
19325
Total emission
(ou/s)
Day
Night
37500
26738
64238
2250
26738
28988
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Additional data - 1
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Complaints records obtained from
neighbouring borough (to north east of the
site)
Complaint locations lay:
outside 5 ou.m-3 contour presented by
operator
within 5 ou.m-3 contour presented by AEAT
Complainants describe odour as ‘fruity,
citrousy’ -
Additional data - 2
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Complainants describe odour as ‘fruity,
citrousy’ Fresh waste
Bottom of dustbin,
rotten cabbage,
fruity/citrous,
acrid/putrid
Young decomposing
waste
Sweet, sulphurous,
gruity, citrousy,
gassy
Older mature waste
Citrousy (lemonlike), fruity, gassy,
pungent
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Outcome
Decision immanent 12 months after
finishing the planning appeal
Points to consider
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Data collection must reflect the range of
emission conditions likely to occur
Modelling should be targeted at assessing the
more sensitive portion of the population
especially in a new situation
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