-
Dawn Meats Ireland Unlimited
Company
Carroll’s Cross, Kilmacthomas, Co. Waterford
Appendix 7-1-3-4 -
Emissions Overview -
Impact Assessment Report
-
Air
August 2018
Redkite Environmental Ltd Registered Office: Hunter’s Moon,
Ballykeane Road, Redcross, Co. Wicklow, Ireland
Registration No: 542716
Siobhan Maher Managing Director Paul Whelan Director
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Control Sheet
Document Title: Appendix 7.1.3.4 – Emissions
Overview - Impact Assessment
Report - Air
Document
No.
P018_01_7.1.3.4
Rev Description Originator Reviewer Change Date 01 Document S.
Maher S. Maher Final 29/8/2018
Redkite Environmental Ltd Registered Office: Hunter’s Moon,
Ballykeane Road, Redcross, Co. Wicklow, Ireland
Registration No: 542716
Siobhan Maher Managing Director Paul Whelan Director
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Dawn Meats Ireland Unlimited Company Carroll’s Cross
Kilmacthomas
Co. Waterford
Appendix 7-1-3-4 – Emissions Overview – Impact
Assessment Report - Air
Contents
1. Introduction
..................................................................................................................
1
2. Methodology
...............................................................................................................
1
3. Existing Conditions
.....................................................................................................
2
4. Impact Assessment
....................................................................................................
2
5. Conclusions and Recommendations
...................................................................
3
6. References
...................................................................................................................
4
Appendices
Appendix 1 Odour Impact Assessment Report, Odour Monitoring
Ireland
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Dawn Meats Ireland Unlimited Company
Carroll’s Cross, Co. Waterford Aug 2018
Appendix 7.1.3.4 – Emissions Overview - Impact Assessment -
Air
Redkite Environmental Ltd. Page 1 of 4
1. Introduction
This attachment sets out the assessment of impacts on air
arising from the
operation of the Dawn Meats Ireland Unlimited Company (DMIUC)
facility at
Carroll’s Cross.
1.1 Statement on Emissions of Main Polluting Substances
SI 137/2013 Environmental Protection Agency (Industrial
Emissions) (Licensing)
Regulations, 2013 set out an indicative list of the principal
polluting substances
to be taken into account by the Agency when setting Emission
Limit values.
The following can be stated in this regard:
• Emissions of sulphur oxides, nitrogen oxides and particulates
can arise infrequently from the back-up boiler and emergency
generator on site.
• There are no emissions from the facility of any other other
principal polluting substances to air as listed in the
Schedule.
• The thermal input of the boiler on site is 500KW in size and
is used as a back-up only to the heat recovery system. A 2 MW
generator is present
on site however this is only for emergency use. Less than 1 m3
of gasoil
was used in 2017 thus demonstrating the insignificant potential
for
impairment of air quality from emissions of sulphur oxides,
nitrogen oxides
and particulates to air from these sources.
• There are no process point sources to air.
Accordingly, there are no significant or major point source
emissions to air.
Fugitive emissions may occur from elements of the Waste Water
Treatment
System (WWTS). Accordingly, an odour assessment is presented in
this
attachment.
A separate receiving environment report has not prepared for
this thematic
because there are no point source emissions of significance to
be assessed that
could potentially impact on the ambient air quality and the main
impact under
the thematic air is odour assessment.
2. Methodology
The odour assessment which forms the main aspect of this
attachment was
completed by Dr. Brian Sheridan of Odour Monitoring Ireland
(OMI).
The odour assessment was performed in accordance with
currently
recommended international guidance and practice for the
assessment of
odours (UK Environment Agency H4 and Irish EPA AG4 guidance
documents).
Odour sampling and measurement was conducted at the WWTS and
dispersion modelling was used to assess the predicted odour
concentrations
on the surrounding area.
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Dawn Meats Ireland Unlimited Company
Carroll’s Cross, Co. Waterford Aug 2018
Appendix 7.1.3.4 – Emissions Overview - Impact Assessment -
Air
Redkite Environmental Ltd. Page 2 of 4
A copy of the full OMI report is contained in Appendix 1
including a detailed
description of the methodology employed.
3. Existing Conditions DMIUC has not received any odour
complaints from surrounding Odour
Sensitive Locations (OSLs). Within the site boundary, odour has
been noted at
the Drum Screen Room, Settlement Ponds 1 and 2 and also in
association with
some Ponds e.g. 1 – 6.
The predicted overall emission odour rates from the existing
WWTS elements
following on site sampling has been completed by OMI. Full
details are
presented in OMI’s full report contained in Appendix 1, Table
4.1. A summary
table is provided below.
Table 1: Predicted Overall Emission Odour Rates from On-site
Sources
Odour Source Odour Emission Rate (OER)
(OuE/s)
Drum Screen Room 5,430
MBBR 888
Settlement Pond 1 1,617
Settlement Pond 2 1,621
Pond 1 10,127
Pond 2 835
Pond 3 453
Pond 4 742
Pond 5 796
Pond 6 1,533
Pond 7 3,349
Pond 8 2,012
Pond 9 916
Pond 10
927
Total OER 31,244
4. Impact Assessment
Odour Impact Criterion for Odours
The odour impact criterion chosen for the analysis of the output
data from the
dispersion model is based on recommended levels in EPA / EA
guidance for
such operations. The 1-hour average shall be less than 3.0
OuE/m3 at the 98th
percentile of worst case total annual hours, as measured at the
nearest OSL. In
order to comply with recent guidance provided by the EPA and EA,
five years
of meteorological data was screened and the worst-case year used
to present
data (yr 2015 Cork Airport was considered worst case) (AG4
Guidance
document and EA - ADMU).
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Carroll’s Cross, Co. Waterford Aug 2018
Appendix 7.1.3.4 – Emissions Overview - Impact Assessment -
Air
Redkite Environmental Ltd. Page 3 of 4
Model Output – Existing
Aermod Prime (18081) was used to determine the odour impact of
the existing
operational WWTS emission sources. The output data was analysed
to
calculate predicted odour emission contribution of the overall
existing
operational WWTS during routine operation to odour plume
dispersal at the
98th percentile for an odour concentration of less than or equal
to 3.0 OuE.m-3.
The visual assessment of the odour plume spread is shown in
Figure 7.2
contained in the OMI Report in Appendix 1. In summary, the
nearest OSLs,
Carroll’s Cross Inn (R1) to the north and Cross Electric (R2) to
the northeast are
predicted to perceive an odour concentration in the range of 2.1
– 2.6 OuE.m-
3 for the 98%ile of hourly averages which is below the
criterion.
As shown in Figure 7.2, Appendix 1, parts of the Waterford
Greenway are
predicted to be greater than 3.0 OuE/m3 for the 98%ile of worst
case total
annual hours (175 hours). Duration and frequency are important
considerations
in this context as well as the non-static nature of receptors.
Users of the
Greenway will pass by the facility quickly therefore any
negative impact will be
momentary at most. The frequency is likely to be insignificant
when considering
the frequency of occurrence (175 hours) and the frequency of use
by individual
users. Accordingly, no significant impacts are anticipated.
The modelling undertaken by OMI assessed the existing
operational conditions
of approx. 95 tonnes per day. The WWTS has adequate capacity for
additional
flows that could arise from maximum production capacity.
Existing measures
to ensure that odour is minimised will continue to be
implemented including:
• Implementation of operational manuals prepared by the MBBR and
ICW designers;
• Ensuring that the main factors affecting potential odour
generation are maintained including optimal water depths in the
ponds and ensuring
waste CAT1 material is regularly removed from the Drum
Screen.
5. Conclusions and Recommendations
There are no major point source emissions present at the DMIUC
facility at
Carroll’s Cross. The back-up boiler represents a minor emission
point (A3-1). The
emergency generator represents an abnormal emission (A4-1).
Fugitive emissions can occur from elements of the WWTS. Odour
sampling and
odour dispersion modelling were completed to assess the impact
off-site at
sensitive receptors.
The main conclusion from the assessment is that predicted level
of odour from
the operational WWTS is not likely to generate odour impact in
the vicinity of
the facility. A number of discrete OSLs (Carroll’s Cross Inn and
Cross Electric)
were incorporated into the model. Each discrete OSL will
perceive an odour
concentration in in the range of 2.10 to 2.60 OuE/m3 for the
98th percentile of
hourly averages which are below the criterion.
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Dawn Meats Ireland Unlimited Company
Carroll’s Cross, Co. Waterford Aug 2018
Appendix 7.1.3.4 – Emissions Overview - Impact Assessment -
Air
Redkite Environmental Ltd. Page 4 of 4
The existing WWTS has adequate capacity to treat wastewater
arisings from full
production capacity. Accordingly, it is not anticipated that an
odour issue is
likely to arise from a full production capacity scenario. DMIUC
implement
operational manuals for both the ICW and MBBR which include for
measures
to minimise odour generation such as maintaining optimum water
depths in the
ICW ponds.
The facility has never received any complaints from the public
regarding
odour.
6. References
Refer to OMI report in Appendix 1.
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Ap
pe
nd
ix 1
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ODOUR IMPACT ASSESSMENT OF THE WASTE WATER TREATMENT SYSTEM
LOCATED IN
DAWN MEATS IRELAND LTD, CARROLS CROSS, WATERFORD, CO.
WATERFORD
PERFORMED BY ODOUR MONITORING IRELAND ON BEHALF REDKITE
ENVIRONMENTAL LTD
PREPARED BY: Dr. Brian Sheridan ATTENTION: Ms. Siobhan Maher
DATE: 01
st July 2018 Ver.1 & 05
th July 2018 Ver.2
REPORT NUMBER: 2018297(2) DOCUMENT VERSION: Document Ver. 002
REVIEWERS: Ms. Siobhan Maher
ODOUR MONITORING IRELAND LTD Unit 32 De Granville Court, Dublin
Rd, Trim, Co. Meath Tel: +353 46 9437922 Mobile: +353 86 8550401
E-mail: [email protected] www.odourireland.com
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OwnerAttachment 9.1
Owner
-
Document No. 2018297(2) Dawn Meats Ireland Ltd
www.odourireland.com i
TABLE OF CONTENTS Section number Page number
1. Executive Summary
..................................................................................
iii 2. Introduction
................................................................................................
1 3. Materials and Methods
..............................................................................
2
3.1. Odour sampling and analysis
.........................................................................................
2 3.1.1. Odour sampling
......................................................................................................
2 3.1.2. Olfactometry
...........................................................................................................
2 3.1.3. Odour measurement in accordance with the EN13725:2003
................................... 3 3.1.4. What is an odour unit?
............................................................................................
3 3.1.5. Odour emission rate calculation.
.............................................................................
3
3.2. Model assumptions
.......................................................................................................
4 3.3. Dispersion modelling
.....................................................................................................
5
3.3.1. Atmospheric dispersion modelling of odours: What is
dispersion modelling? ........... 5 3.3.2. AERMOD Prime
.....................................................................................................
5
3.4. Odour impact criterion for odours
...................................................................................
6 3.5. Meteorological data.
......................................................................................................
6 3.6. Terrain data.
..................................................................................................................
6
4. Results
........................................................................................................
7 4.1. Odour emission dataset for Scenario 1
..........................................................................
7 4.2. Results of odour dispersion modelling for Scenario 1
..................................................... 9
5. Discussion of results
...............................................................................
10 5.1. Odour plume dispersal for Scenario 1 – Model 1
.......................................................... 10
6. Conclusions
.............................................................................................
11 7. Appendix I - Odour dispersion modelling contour results
................... 12
7.1. Facility layout, boundary and receptor locations
........................................................... 12 7.2.
Predicted odour contour plots for odour emissions for Model 1.
................................... 13
8. References
................................................................................................
14 9. Appendix III - Meteorological data examined and used in the
dispersion modelling
exercise.........................................................................
15 Total 15
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Document No. 2018297(2) Dawn Meats Ireland Ltd
www.odourireland.com ii
Document Amendment Record
Client: Redkite Environmental Ltd
Title: Odour impact assessment of the waste water treatment
system located in Dawn Meats
Ireland Ltd located in Carrols Cross, Waterford, Co.
Waterford.
Project Number: 2018297(1)
Document Reference: Odour impact assessment of the waste water
treatment system located in Dawn Meats Ireland Ltd located in
Carrols Cross, Waterford, Co. Waterford.
2018297(1) Document for review BAS JWC BAS 01/07/2018
Revision Purpose/Description Originated Checked Authorised
Date
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Document No. 2018297(2) Dawn Meats Ireland Ltd
www.odourireland.com iii
1. Executive Summary Odour Monitoring Ireland Ltd was
commissioned by Redkite Environmental Ltd to carry out an odour
sampling and odour dispersion modelling assessment of odour
emissions from the operational Waste water treatment system located
in Dawn Meats Ireland Ltd, Carrols Cross, Waterford, Co. Waterford.
The purpose of this assessment was to determine the potential for
the generation of odour impact on the surrounding population from
operations at the existing waste water treatment system. Following
a site assessment utilising odour sampling and analysis techniques,
one odour emission dataset was developed to determine the potential
odour impact of odour emissions from the operational waste water
treatment system. This included: Ref Scenario 1: Predicted overall
odour emission rate from existing operational waste
water treatment system during routine operation (see Table 4.1)
– Model 1
Details of Model 1 is described in Section 3.2. Aermod Prime
(18081) was used to determine the overall odour impact of the
operational existing waste water treatment system as set out in
odour impact criteria presented in Section 3.5. The output data was
analysed to calculate:
• Model 1 - Predicted odour emission contribution of overall
existing operational waste water treatment system during routine
operation (see Table 4.1), to odour plume dispersal at the 98
th percentile for an odour concentration of less than or equal
to 3.0 OuE
m-3
(see Figure 7.2). These computations give the odour
concentration at each Cartesian grid receptor location that is
predicted to be exceeded for 2% (175 hours) over 5 years of
screened hourly sequential meteorological data (Cork Airport 2011
to 2015 inclusive). The Cartesian receptor grid was 20 and 50 m
spaced given a total receptor number of 1894 over an area of 3.07
km
2.
The following conclusions were gathered from the study:
• With regards to Scenario 1 – Model 1, as can be observed, it
is predicted that the levels of odours from the operational waste
water treatment system is not likely to generate odour impact in
the vicinity of the facility. A number of discrete sensitive
receptors were incorporated into the model (R1 to R2). Receptor R1
and R2 will perceive an odour concentration in in the range of 2.10
to 2.60 OuE/m
3 for the 98
th percentile of hourly
averages (see Figure 7.2).
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Document No. 2018297(2) Dawn Meats Ireland Ltd
www.odourireland.com 1
2. Introduction Odour Monitoring Ireland was commissioned by
Redkite Environmental Ltd to perform an odour survey and dispersion
modelling assessment of the operational existing Waste water
Treatment system emissions located in Dawn Meats Ireland Ltd
utilising dispersion modelling software Aermod Prime (18081). Like
the majority of facilities, the operation of the WWTS is faced with
the issue of preventing odours causing impact to the public at
large. Utilising the existing site design and measured odour
emission data of the existing operations within the waste water
treatment system dispersion-modelling techniques were used to
establish the predictive odour impact beyond the boundary of the
facility in accordance with the standard requirements. One odour
emission scenario was developed to take account of routine
operations and design for the existing facility. This odour
emission rate and specified source characteristics were inputted
into Aermod Prime in order to determine the overall odour impact
beyond the boundary of the facility. This assessment was performed
in accordance with currently recommended international guidance and
practice for the assessment of odours (Environment Agency H4 and
Irish EPA AG4 guidance documents).
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Document No. 2018297(2) Dawn Meats Ireland Ltd
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3. Materials and Methods This section will describe the
materials and methods used for the odour sampling and dispersion
modelling assessment. 3.1. Odour sampling and analysis This section
will provide the materials and methods used to sample and analyse
odours from the operational WWTS.
3.1.1. Odour sampling
Point sampling In order to obtain air samples for odour
assessment, a static sampling method was used where air samples
were collected in 40 to 60 litre pre-conditioned Nalophan
NA bags using a vacuum
sampling device over a 15 minute period. The sampler operates on
the 'lung principle', whereby the air is removed from a rigid
container around the bag by a battery powered SKC vacuum pump at a
rate of 4 l min
-1. This caused the bag to fill through a stainless steel and
PTFE tube whose
inlet is placed in ambient air, with the volume of sample equal
to the volume of air evacuated from the rigid container. All
odour-sampling bags were pre-conditioned and flushed with odourous
air to remove any interference from the sample material. Area flux
hood sampling In order to measure the odour emission rate from area
odour surfaces a calibrated wind tunnel method was used. This
calibrated sampling hood allowed for the accurate determination of
odour emission rate from the surface of the tanks. In combination
with the point source static sampling method a 60-litre sample was
obtained (Jiang et al., 2002, USEPA, 1998).
3.1.2. Olfactometry
Olfactometry using the human sense of smell is the most valid
means of measuring odour (Dravniek et al, 1986) and at present is
the most commonly used method to measure the concentration of odour
in air (Hobbs et al, 1996). Olfactometry is carried out using an
instrument called an olfactometer. Three different types of dynamic
dilution olfactometers exist:
• Yes/No Olfactometer
• Forced Choice Olfactometer
• Triangular Forced Choice Olfactometer. In the dynamic dilution
olfactometer, the odour is first diluted and is then presented to a
panel of screened panellists of no less than four (CEN, 2003)
Panellists are previously screened to ensure that they have a
normal sense of smell (Casey et al., 2003). According to the CEN
standard this screening must be performed using a certified
reference gas n-butanol. This screening is applied to eliminate
anosmia (low sensitivity) and super-noses (high sensitivity). The
odour analysis has to be undertaken in a low odour environment such
as an air-conditioned odour free laboratory. Analysis should be
performed preferably within 8 to 12 hours of sampling.
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Document No. 2018297(2) Dawn Meats Ireland Ltd
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3.1.3. Odour measurement in accordance with the EN13725:2003
An ECOMA TO8 dynamic yes/no olfactometer was used throughout the
measurement period to determine the odour threshold concentration
of the sample air. The odour threshold concentration is defined as
the dilution factor at which 50% of the panel can just detect the
odour. Only those panel members who pass screening tests with
n-butanol (certified reference gas, CAS 72-36-3) and who adhered to
the code of behaviour were selected as panellists for olfactometry
measurements (CEN, 2003). Odour measurement was carried out in an
odour free laboratory in accordance with EN13725:2003. The analyses
were carried out in the laboratory of Odour Monitoring Ireland in
Trim Co. Meath.
3.1.4. What is an odour unit?
The odour concentration of a gaseous sample of odourant is
determined by presenting a panel of selected screened human
panellists with a sample of odourous air and varying the
concentration by diluting with odourless gas, in order to determine
the dilution factor at the 50% detection threshold. The Z50 value
(threshold concentration) is expressed in odour units (OuE m
-3).
The European odour unit is that amount of odourant(s) that, when
evaporated into one cubic metre of neutral gas (nitrogen), at
standard conditions elicits a physiological response from a panel
(detection threshold) equivalent to that elicited by one European
Reference Odour Mass (EROM) evaporated in one cubic meter of
neutral gas at standard conditions. One EROM is that mass of a
substance (n-butanol) that will elicit the Z50 physiological
response assessed by an odour panel in accordance with this
standard. n-Butanol is one such reference standard and is
equivalent to 123µg of n-butanol evaporated in one cubic meter of
neutral gas at standard conditions (CEN, 2003).
3.1.5. Odour emission rate calculation.
The measurement of the strength of a sample of odourous air is,
however, only part of the problem of quantifying odour. Just as
pollution from a stack is best quantified by a mass emission rate,
the rate of production of an odour is best quantified by the odour
emission rate. For a chimney or ventilation stack, this is equal to
the odour threshold concentration (OuE m
-3) of the
discharge air multiplied by its flow-rate (m3 s
-1). It is equal to the volume of air contaminated every
second to the threshold odour limit (OuE s-1
). The odour emission rate can be used in conjunction with
dispersion modelling in order to estimate the approximate radius of
impact or complaint (Hobson et al, 1995). Area source mass emission
rates/flux were calculated as either OuE m
-2 s
-1 or OuE s
-1 depending
if they are being represented as discrete point sources or area
sources in the atmospheric dispersion model. The overall odour
emission rates for the existing scenario is presented in Table
4.1.
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3.2. Model assumptions The following model assumptions were used
to construct and generate the output results from the dispersion
model. These include:
• The input data used within the dispersion model was obtained
from measurements carried out on site.
• One scenario was assessed to take account of client
requirements. Ref Scenario 1: Predicted overall odour emission rate
from existing operational waste
water treatment system during routine operation (see Table 4.1)
– Model 1
• AERMOD Prime (18081) dispersion model was used to assess the
predicted odour concentrations on the surrounding area.
• Five years of hourly sequential meteorological data was
screened within the dispersion model in order to provide
statistical sound predictions for the impact assessment. Cork
Airport 2011 to 2015 inclusive was used for the operation of the
dispersion model while Cork Airport 2015 was determined as worst
case impact year. This is in keeping with current national and
international recommendations (EPA Guidance AG4 and EA). In
addition, AERMOD incorporates a meteorological pre-processor AERMET
PRO. The AERMET PRO meteorological preprocessor requires the input
of surface characteristics, including surface roughness (z0), Bowen
Ratio and Albedo by sector and season, as well as hourly
observations of wind speed, wind direction, cloud cover, and
temperature. The values of Albedo, Bowen Ratio and surface
roughness depend on land-use type (e.g., urban, cultivated land
etc) and vary with seasons and wind direction. The assessment of
appropriate land-use type was carried out to a distance of 10km
from the meteorological station for Bowen Ratio and Albedo and to a
distance of 1km for surface roughness in line with USEPA
recommendations
• The 98th percentile of maximum hourly predicted concentrations
was used to provide the
output data from the dispersion model.
• Emissions to the atmosphere from the existing operations were
assumed to occur 24 hours each day / 7 days per week over a
standard year at 100% output for all sources.
• All building wake affects were assessed within the dispersion
model.
• Terrain effects were accounted within the model using AERMAP
software and digital data from OSI (10 m spaced).
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3.3. Dispersion modelling 3.3.1. Atmospheric dispersion
modelling of odours: What is dispersion modelling? Any material
discharged into the atmosphere is carried along by the wind and
diluted by wind turbulence, which is always present in the
atmosphere. This process has the effect of producing a plume of air
that is roughly cone shaped with the apex towards the source and
can be mathematically described by the Gaussian equation.
Atmospheric dispersion modelling has been applied to the assessment
and control of odours for many years, originally using Gaussian
form ISCST 3 and more recently utilising advanced boundary-layer
physics models such as ADMS and AERMOD (Keddie et al. 1992). Once
the odour emission rate from the source is known, (OuE s
-1),
the impact on the vicinity can be estimated. These models can
effectively be used in three different ways: firstly, to assess the
dispersion of odours and to correlate with complaints; secondly, in
a “reverse” mode, to estimate the maximum odour emissions which can
be permitted from a site in order to prevent odour complaints
occurring; and thirdly, to determine which process is contributing
greatest to the odour impact and estimate the amount of required
abatement to reduce this impact within acceptable levels (McIntyre
et al. 2000). In this latter mode, models have been employed for
imposing emission limits on industrial processes, odour control
systems and intensive agricultural processes (Sheridan et al.,
2002). 3.3.2. AERMOD Prime The AERMOD model was developed through a
formal collaboration between the American Meteorological Society
(AMS) and U.S. Environmental Protection Agency (U.S. EPA). AERMOD
is a Gaussian plume model and replaced the ISC3 model in
demonstrating compliance with the National Ambient Air Quality
Standards (Porter et al., 2003) AERMIC (USEPA and AMS working
group) is emphasizing development of a platform that includes air
turbulence structure, scaling, and concepts; treatment of both
surface and elevated sources; and simple and complex terrain. The
modelling platform system has three main components: AERMOD, which
is the air dispersion model; AERMET, a meteorological data
pre-processor; and AERMAP, a terrain data pre-processor (Cora and
Hung, 2003). AERMOD is a Gaussian steady-state model which was
developed with the main intention of superseding ISCST3 (NZME,
2002). The AERMOD modeling system is a significant departure from
ISCST3 in that it is based on a theoretical understanding of the
atmosphere rather than depend on empirical derived values. The
dispersion environment is characterized by turbulence theory that
defines convective (daytime) and stable (nocturnal) boundary layers
instead of the stability categories in ISCST3. Dispersion
coefficients derived from turbulence theories are not based on
sampling data or a specific averaging period. AERMOD was especially
designed to support the U.S. EPA’s regulatory modeling programs
(Porter at al., 2003) Special features of AERMOD include its
ability to treat the vertical in-homogeneity of the planetary
boundary layer, special treatment of surface releases,
irregularly-shaped area sources, a three plume model for the
convective boundary layer, limitation of vertical mixing in the
stable boundary layer, and fixing the reflecting surface at the
stack base (Curran et al., 2006). A treatment of dispersion in the
presence of intermediate and complex terrain is used that improves
on that currently in use in ISCST3 and other models, yet without
the complexity of the Complex Terrain Dispersion Model-Plus
(CTDMPLUS) (Diosey et al., 2002).
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3.4. Odour impact criterion for odours The odour impact
criterion chosen for the analysis of the output data from the
dispersion was based on recommended levels in EPA / EA guidance for
such operations. The 1 hour average shall be less than 3.0
OuE/m
3 at the 98
th percentile of worst case total annual hours, as measured
at the nearest odour sensitive location. In order to comply with
recent guidance provided by the EPA and EA, five years of
meteorological data was screened and the worst case year used to
present data (yr 2015 Cork Airport was considered worst case) (AG4
Guidance document and EA - ADMU). 3.5. Meteorological data. Cork
Airport met station 2011 to 2015 inclusive was used for the
operation of Aermod Prime 18081. This allowed for the determination
of dispersion for 5 years of meteorological data for the
determination of overall odour impact from the existing WWTS
operations beyond the boundary of the facility. Section 9 presents
the windrose and tabular statistics for Cork Airport meteorological
station for years 2011 to 2015 inclusive. 3.6. Terrain data.
Topography affects in the vicinity of the site were accounted for
in the model utilising topo data as gathered from OSI. All building
wake effects are accounted for in the modelling scenario (i.e.
building effects on point sources) as this can have a major effect
on the odour plume dispersion at short distances. This was
performed using the BPIP Prime algorithm.
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4. Results
This section will present the results obtained from the odour
measurement and dispersion modelling study. 4.1. Odour emission
dataset for Scenario 1 One data set for odour emission rates were
calculated to determine the potential odour impact of the existing
WWTS facility operations utilising odour emission data as gathered
on site. These scenarios included: Ref Scenario 1: Predicted
overall odour emission rate from existing operational waste
water treatment system during routine operation (see Table 4.1)
– Model 1
Aermod Prime (18081) was used to determine the overall odour
impact of the WWTS emission sources as set out in odour impact
criteria presented in Section 3.4.
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Table 4.1 illustrates the odour emission input data measured and
utilised within the dispersion model for existing scenario. The
measured overall odour emission rate from the WWTS is 31,244 OuE/s
on this day of monitoring. Table 4.1. Predicted overall odour
emission rate from existing operational Dawn Meats Ireland WWTS
(ref Scenario 1 – Model 1).
Model 1 - Existing Waste water treatment system
Odour Sources Exposed Area
(m2)
Diameter (m) Source type Average Odour threshold conc.
(OuE/m3)
Average Odour emission flux (OuE/m
2/s)
Volume flow
(m3/hr)
Odour emission rate (OuE/s)
Notes
Drum screen room1
2 m2 opening - Volume 1,448 - 3.75 5,430 -
MBBR Tank 68.80 4.68 Area - 12.90 - 888 -
Settlement pond 1 109.3 - Area - 14.80 - 1,617 -
Settlement pond 2 109.5 - Area - 14.80 - 1,621 Settlement pond 1
data was used to represent Settlement pond 2 data
Pond 1 1235.0 - Area - 8.20 - 10,127 -
Pond 2 417.6 - Area - 2.00 - 835 -
Pond 3
226.7 - Area - 2.00 - 453 Pond 2 data was used to represent Pond
3 data
Pond 4
370.9 - Area - 2.00 - 742 Pond 2 data was used to represent Pond
4 data
Pond 5 397.8 - Area - 2.00 - 796 Pond 2 data was used to
represent Pond 5 data
Pond 6 766.6 - Area - 2.00 - 1,533 Pond 2 data was used to
represent Pond 6 data
Pond 7 1674.6 - Area - 2.00 - 3,349 Pond 2 data was used to
represent Pond 7 data
Pond 8 2872.3 - Area - 0.70 - 2,011 -
Pond 9 1307.9 - Area - 0.70 - 916 Pond 8 data was used to
represent Pond 9 data
Pond 10 1323.8 - Area - 0.70 - 927 Pond 8 data was used to
represent Pond 10 data
Total OER (OuE/s) - - - - - - 31,244 -
Notes:
1 denotes leakage rate based on Valentine model and assuming and
average wind speed of 5 m/s.
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4.2. Results of odour dispersion modelling for Scenario 1 Aermod
Prime (18081) was used to determine the overall odour impact of the
existing operational WWTS emission sources as set out in odour
impact criteria in Section 3.4. The output data was analysed to
calculate:
• Model 1 - Predicted odour emission contribution of overall
existing operational waste water treatment system during routine
operation (see Table 4.1), to odour plume dispersal at the 98
th percentile for an odour concentration of less than or equal
to 3.0 OuE
m-3
(see Figure 7.2). These odour impact criterions were chosen so
as to allow for visual assessment of the odour plume spread from
the emission sources located within the waste water treatment
system. These computations give the odour concentration at each
Cartesian grid receptor location that is predicted to be exceeded
for 2% (175 hours) for worst case year Cork Airport 2015
meteorological data. The Cartesian receptor grid was 20 and 50 m
spaced. This will allow for the predictive analysis of any
potential impact on the neighbouring sensitive locations while the
facility is in operation. It will also allow the operators of the
facility site to assess the effectiveness of their odour
abatement/minimisation strategies. The intensity of the odour from
two or more sources from the facility operation will depend on the
strength of the initial odour threshold concentration from the
sources and the distance downwind at which the prediction and/or
measurement is being made. Where the odour emission plumes from a
number of sources combine downwind, then the predicted odour
concentrations may be higher than that resulting from an individual
emission source. It is important to note that various odour sources
have different odour characters. This is important when assessing
those odour sources to minimise and/or abate. Although an odour
source may have a high odour emission rate, the corresponding odour
intensity (strength) may be low and therefore it is easily diluted.
Those sources that express the same odour character, as an odour
impact should be investigated first for abatement/minimisation
before other sources are examined as these sources are the driving
force behind the character of the perceived odour.
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5. Discussion of results This section will discuss the results
obtained during the study. 5.1. Odour plume dispersal for Scenario
1 – Model 1
The plotted odour concentrations of ≤ 3.0 OuE m-3
for the 98th percentile for the existing
operational WWTS operation is illustrated in Figure 7.2. A
number of discrete sensitive receptors were incorporated into the
model (R1 to R2). Receptor R1 and R2 at these locations will
perceive an odour concentration in in the range of 2.10 to 2.60
OuE/m
3 for the 98
th percentile of hourly averages.
Table 5.1 presents the predicted odour concentration at each
receptor location for each of the Model scenario. Table 5.1.
Predicted worst case 98
th percentile odour concentrations at each sensitive
receptor
(Model 1) for worst case meteorological year – Cork Airport
2015.
Receptor identity X coordinate
(m) Y coordinate
(m)
Model 1 - 98%ile odour value worst case yr. Cork Airport
2015
(OuE/m3)
R1 644944.58 608456.43 2.20
R2 645124.20 608370.94 2.60
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6. Conclusions The following conclusions were gathered from the
study:
• With regards to Scenario 1 – Model 1, as can be observed, it
is predicted that the levels of odours from the operational waste
water treatment system is not likely to generate odour impact in
the vicinity of the facility. A number of discrete sensitive
receptors were incorporated into the model (R1 to R2). Receptor R1
and R2 will perceive an odour concentration in in the range of 2.10
to 2.60 OuE/m
3 for the 98
th percentile of hourly averages
(see Figure 7.2).
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7. Appendix I - Odour dispersion modelling contour results 7.1.
Facility layout, boundary and receptor locations
Figure 7.1. Existing Dawn Meats Ireland facility layout,
location and receptor locations
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7.2. Predicted odour contour plots for odour emissions for Model
1.
Figure 7.2. Predicted odour emission contribution of Dawn Meats
Ireland facility for Model 1 to odour plume dispersal for an odour
concentration of less than or equal to 3.0 OuE m
-3 ( ) at the 98
th
percentile of hourly averages for worst case meteorological year
Cork Airport 2015.
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8. References 1. Callan, B.T., (1993). Noses Knows Best. In
malodour measurement and control. Proceedings of
the International Tydnall School, September. 134-145. 2. CEN,
(2003). EN13725-Air-quality-Determination of odour concentration by
dynamic
olfactometry. Brussels, Belgium. 3. DOE, (1993). Report by the
Inspector on a Public Inquiry into the Appeal by Northumbrian
Water Limited for Additional Sewage treatment facilities on land
adjacent to Spitial Burns, Newbriggin-by-the-Sea, Northumberland in
March 1993. DoE ref APP/F2930/A/92/206240.
4. Dravniek, A., (1986). Atlas of odor character profiles. ASTM
Committee on sensory evaluation of materials and products, ASTM
data series. Baltimore, MD, USA.
5. EPA, (2001). Odour impacts and odour emission control
measures for intensive agriculture. Commissioned by the
Environmental Protection Agency (Ireland). OdourNet UK Ltd.
6. Longhurst, P., (1998). Odour impact assessment of an
extension to the Brogborough landfill site. IREC, Cranfield
University, England.
7. McIntyre, A., (2000). Application of dispersion modelling to
odour assessment; a practical tool or a complex trap. Water Science
and Technology, 41 (6). 81-88.
8. Sheridan, B.A. (2002). In house odour intensity and hedonic
tone profile data of different odourous sources. Unpublished.
9. Sheridan, B.A., (2001). Controlling atmospheric emissions-BAT
Note Development, UCD Environmental Engineering Group, Department
of Agricultural and Food Engineering, UCD, Dublin 2.
10. Sheridan, B.A., Hayes, E.T., Curran, T.P., Dodd, V.A.,
(2003). A dispersion modelling approach to determining the odour
impact of intensive pig production units in Ireland. Bioresource
Technology. Published.
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9. Appendix III - Meteorological data examined and used in the
dispersion
modelling exercise
Table 9.1. Tabular illustration of Cork Airport meteorological
files for Years 2011 to 2015 inclusive (5 years).
5 year Meteorological file for Cork Airport 2011 to 2015
inclusive
Dir \ Speed
-
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Figure 9.1. Windrose illustration of meteorological files Cork
Airport 2011 to 2015 inclusive.
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