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Devon County Council 22 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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and moving the earth, as well as by the movement of the vehicles on potentially dusty surfaces. Handling and storage of construction materials (aggregates) use of haulage roads and unsurfaced areas are also potential sources of dust generation. The potential dust emission magnitude for each area is described in Table 5-1.
Table 5-1 Potential Dust Emission Magnitude
Activity Comments Dust Emission Magnitude
Area 1
Demolition No building demolition required. Removal of existing road top surface Medium
Earthworks
Some embankment work close to Drumbridges roundabout. Total area is large at >10,000m2 however it is not expected to worked in its entirety simultaneously. Anticipated 5 to 10 heavy earth moving vehicles at any one time Medium
Construction The construction area is large at >10,000m2 and there is use of potentially dusty construction material, i.e. aggregates Medium
Trackout It is anticipated that a maximum of >50HDV movements could occur in one day and there is potential for the unpaved road length to exceed 100m Large
Area 2
Demolition No building demolition required. Removal of existing road top surface Medium
Earthworks
Some embankment work after the roundabout and as the lanes diverge. Total area is large at >10,000m2 however it is not expected to worked in its entirety simultaneously. Anticipated 5 to 10 heavy earth moving vehicles at any one time Medium
Construction The construction area is large at >10,000m2 and there is use of potentially dusty construction material, i.e. aggregates Medium
Trackout It is anticipated that a maximum of >50HDV movements could occur in one day and there is potential for the unpaved road length to exceed 100m Large
Area 3
Demolition No building demolition required. Removal of existing road top surface Medium
Earthworks
Some cutting excavation leading up to and after the Stover School access. Total area is large at >10,000m2 however it is not expected to worked in its entirety simultaneously. Anticipated 5 to 10 heavy earth moving vehicles at any one time Medium
Construction The construction area is large at >10,000m2 and there is use of potentially dusty construction material, i.e. aggregates Medium
Trackout It is anticipated that a maximum of >50HDV movements could occur in one day and there is potential for the unpaved road length to exceed 100m Large
Area 4
Demolition No building demolition required. Removal of existing road top surface Medium
Earthworks
Some cutting excavation either side of the access to Blatchford Farm, embankment works at The Little House. Total area is large at >10,000m2 however it is not expected to worked in its entirety simultaneously. Anticipated 5 to 10 heavy earth moving vehicles at any one time Medium
Construction The construction area is large at >10,000m2 and there is use of potentially dusty construction material, i.e. aggregates Medium
Trackout It is anticipated that a maximum of >50HDV movements could occur in one day and there is potential for the unpaved road length to exceed 100m Large
Area 5
Demolition No building demolition required. Removal of existing road top surface Medium
Earthworks
Various sections of cutting and embankment works including large area at the A382/JettyMarsh II roundabout. Total area is large at >10,000m2 however it is not expected to worked in its entirety simultaneously. Anticipated >10 heavy earth moving vehicles at any one time Large
Construction The construction area is large at >10,000m2 and there is use of potentially dusty construction material, i.e. aggregates Medium
Devon County Council 23 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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Activity Comments Dust Emission Magnitude
Trackout It is anticipated that a maximum of >50HDV movements could occur in one day and there is potential for the unpaved road length to exceed 100m Large
5.3 Sensitivity of the Area
The sensitivity of the area takes account of a number of factors:
• the specific sensitivities of receptors in the area;
• the proximity and number of those receptors;
• in the case of PM10, the local background concentration; and
• site-specific factors, such as whether there are natural shelters, such as trees, to reduce the risk of wind-blown dust.
The sensitivity of the area and the factors considered are presented in Table 5-2.
Table 5-2 Sensitivity of the Area
Sensitivity to: Comments Sensitivity
Area 1
Dust Soiling Impacts
Stover Country Park is adjacent to the area, however the amenity areas within the country park are well sheltered by a well-established tree belt. High sensitivity receptors High sensitivity residential receptors in Heathfield are more than 100m away. High sensitivity residential receptors at Ilford Park Polish Home are more than 20m away. The Caravan Park has been considered of medium sensitivity given it is not expected to be occupied year round
Low
Human Health Impacts
The PM10 background 13.4µg/m3 and there are less than 100 receptors within 20m
Low
Ecological Impacts
According to the Air Pollution Information System Stover Park SSSI site interest features are Phragmites australis swamp and reed-beds with associated dragonfly assemblage. These areas are approximately 200m from the scheme area
Low
Area 2
Dust Soiling Impacts
The Stover Golf Club is considered of medium sensitivity at the Club House area is in excess of 50m from the scheme. The Caravan Park has been considered of medium sensitivity given it is not expected to be occupied year round
Low
Human Health Impacts
The PM10 background 13.4µg/m3 and there are less than 100 receptors within 20m
Low
Ecological Impacts
There are no designated ecological habitats adjacent to this area N/A
Area 3
Dust Soiling Impacts
Stover School is considered of high sensitivity and there is the potential for 1 to 10 receptors within 20m and 10 to100 within 50m
High
Human Health Impacts
The PM10 background 14.0µg/m3 and there are less than 100 receptors within 20m
Low
Ecological Impacts
There are no designated ecological habitats adjacent to this area N/A
Area 4
Dust Soiling Impacts
There are 3 high sensitivity (residential) receptors within 20m of the scheme. The green houses (considered of high sensitivity)extend from 40m away from the scheme
High
Human Health The PM10 background 15.2µg/m3 and there are less than 100 receptors within Low
Devon County Council 24 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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Sensitivity to: Comments Sensitivity
Impacts 20m
Ecological Impacts
There are no designated ecological habitats adjacent to this area N/A
Area 5
Dust Soiling Impacts
There are approximately14 high sensitivity (residential) receptors within 20 of the scheme, on Linden Lea (DR9) Berry Knowles (DR10) and numerous on Orleigh Cross
High
Human Health Impacts
The PM10 background 14.2µg/m3 and there are less than 100 receptors within 20m
Low
Ecological Impacts
There are no designated ecological habitats adjacent to this area N/A
5.4 Risk of Impacts
The outcome of the assessment of the potential ‘magnitude of dust emissions’, and the ‘sensitivity of the area’ are combined in the table below to determine the risk of impact which is used to inform the selection of appropriate mitigation.
Table 5-3 Risk of Dust Impacts
Potential Impact Demolition Earthworks Construction Trackout
Magnitude: Medium Medium Medium Large
Area 1 Sensitivity
Dust Soiling Impacts Low Low Risk Low Risk Low Risk Low Risk
Human Health Impacts Low Low Risk Low Risk Low Risk Low Risk
Ecological Impacts Low Low Risk Low Risk Low Risk Low Risk
Magnitude: Medium Medium Medium Large
Area 2 Sensitivity
Dust Soiling Impacts Low Low Risk Low Risk Low Risk Low Risk
Human Health Impacts Low Low Risk Low Risk Low Risk Low Risk
Ecological Impacts N/A N/A N/A N/A N/A
Magnitude: Medium Medium Medium Large
Area 3 Sensitivity
Dust Soiling Impacts High Medium Risk Medium Risk Medium Risk High Risk
Human Health Impacts Low Low Risk Low Risk Low Risk Low Risk
Ecological Impacts N/A N/A N/A N/A N/A
Magnitude: Medium Medium Medium Large
Area 4 Sensitivity
Dust Soiling Impacts High Medium Risk Medium Risk Medium Risk High Risk
Human Health Impacts Low Low Risk Low Risk Low Risk Low Risk
Ecological Impacts N/A N/A N/A N/A N/A
Magnitude : Medium Large Medium Large
Area 5 Sensitivity
Dust Soiling Impacts High Medium Risk Medium Risk Medium Risk High Risk
Human Health Impacts Low Low Risk Low Risk Low Risk Low Risk
Ecological Impacts N/A N/A N/A N/A N/A
Devon County Council 25 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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5.5 Construction Vehicle Exhaust Impacts
Road traffic emissions associated with vehicle movements, particularly HDV movements, during the construction phase of the development have the potential to result in increased concentrations of combustion related pollutants, such as NO2 and PM10 in the vicinity of the development site.
The DMRB states that further assessment of potential air quality impacts should be undertaken if the following criteria are met on any link affected by a proposed development:
• increase in 24-hour AADT flow of more than 1,000-vehicles; and/or
• increase in 24-hour AADT flow of more than 200-HDV.
Detailed information on traffic movements anticipated during construction works was unavailable for the completion of the Air Quality Assessment and will be dependent on the construction scheme decided upon in consultations with the contractor awarded the work. However, the development is not anticipated to result in an increase in movements above the DMRB criteria for the duration of the construction phase.
Devon County Council 26 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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6.0 TRAFFIC EMISSIONS ASSESSMENT – EFFECTS AND SIGNIFICANCE
This section presents the potential air quality impacts associated with the operational phase of the development, including any required mitigation options.
6.1 2019 Opening Year
6.1.1 Nitrogen Dioxide Modelling Results
Assessment against annual mean AQAL
Table 6-1 presents the predicted impact at discrete receptor locations in 2019 against the annual mean AQAL of 40µg/m3. The following comments on the results can be made:
• at the majority of receptors the impact is considered to be negligible, in accordance with the stated assessment methodology;
• moderate adverse impacts are predicted at receptors DR1, DR11, and DR13 due to their proximity to the scheme and predicted percentage change of the AQAL. However the concentration at these receptors with the scheme remains less than 75% of the AQAL;
• slight adverse impacts are predicted at a number of locations within the AQMAs, DR20 (Queen Street), DR21 (Station Road), DR22 (Torquay Road) and DR28 (Broadway in Kingsteignton); and
• moderate adverse impacts are predicted at receptor DT6 on Queens Street, however concentrations are predicted to be less than the AQAL.
Figure A-3 and Figure A-4 (Appendix A) present the concentration isopleths across the scheme area for the DM and DS scenario respective.
Table 6-1 Predicted Annual Mean NO2 Concentrations at Discrete Receptors
ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DR1 13.8 22.0 20.6 55.0 Moderate Adverse
DR2 8.5 9.6 2.8 24.0 Negligible
DR3 10.5 10.5 -0.1 26.3 Negligible
DR4 10.8 10.3 -1.1 25.8 Negligible
DR5 10.2 10.2 0.1 25.6 Negligible
DR6 9.9 9.9 -0.2 24.6 Negligible
DR7 14.3 15.3 2.3 38.1 Negligible
DR8 8.9 9.6 1.7 24.0 Negligible
DR9 11.9 10.7 -3.1 26.7 Negligible
DR10 13.5 15.2 4.2 38.0 Negligible
DR11 15.2 21.3 15.2 53.3 Moderate Adverse
DR12 12.2 10.6 -4.0 26.6 Negligible
DR13 8.1 16.5 20.9 41.2 Moderate Adverse
DR14 8.4 10.7 5.8 26.7 Slight Adverse
DR15 7.8 8.6 1.9 21.5 Negligible
DR16 21.3 14.0 -18.5 34.9 Negligible
Devon County Council 27 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DR17 15.1 11.4 -9.2 28.5 Negligible
DR18 21.2 21.7 1.2 54.2 Negligible
DR19 26.3 27.1 2.2 67.8 Negligible
DR20 30.9 31.9 2.5 79.9 Slight Adverse
DR21 29.4 30.4 2.4 75.9 Slight Adverse
DR22 31.4 31.8 1.1 79.6 Slight Adverse
DR23 23.2 23.6 1.0 59.0 Negligible
DR24 23.8 24.0 0.5 60.0 Negligible
DR25 14.9 15.4 1.1 38.4 Negligible
DR26 24.1 23.4 -1.9 58.5 Negligible
DR27 14.3 13.8 -1.3 34.5 Negligible
DR28 18.6 22.4 9.6 56.0 Slight Adverse
DR29 21.9 20.9 -2.4 52.3 Negligible
DR30 15.9 15.4 -1.2 38.5 Negligible
DR31 13.5 13.1 -0.9 32.8 Negligible
DR32 16.1 14.7 -3.4 36.8 Negligible
DR33 16.4 15.8 -1.5 39.4 Negligible
DR34 12.2 11.1 -2.8 27.8 Negligible
DR35 11.0 10.4 -1.6 26.0 Negligible
DR36 11.1 10.6 -1.2 26.5 Negligible
DR37 15.7 14.7 -2.4 36.8 Negligible
DR38 5.3 5.3 0.1 13.2 Negligible
DR39 11.9 11.4 -1.1 28.6 Negligible
DR40 11.8 11.3 -1.2 28.4 Negligible
DR41 11.2 10.7 -1.1 26.8 Negligible
DR42 30.2 30.6 0.9 76.5 Negligible
DR43 11.9 12.1 0.6 30.3 Negligible
DR44 25.9 26.5 1.5 66.2 Negligible
DR45 20.3 20.1 -0.5 50.3 Negligible
DR46 8.7 8.1 -1.3 20.3 Negligible
DR47 12.8 11.8 -2.6 29.5 Negligible
DT3 29.1 28.1 -2.5 70.1 Negligible
DT6 36.5 37.7 3.0 94.3 Moderate Adverse
DT7 22.5 22.0 -1.2 55.0 Negligible
DT9 12.3 12.2 -0.2 30.4 Negligible
DT16 22.8 22.3 -1.3 55.7 Negligible
DT18 14.8 15.0 0.4 37.5 Negligible
DT19 24.1 25.0 2.1 62.4 Negligible
DT23 31.8 32.8 2.6 82.0 Slight Adverse
DT25 28.8 29.7 2.2 74.2 Negligible
DT32 19.1 22.7 8.9 56.7 Slight Adverse
DT38 24.8 24.0 -1.9 60.0 Negligible
DT54 29.5 28.9 -1.4 72.4 Negligible
DT56 15.6 15.8 0.3 39.5 Negligible
DT58 17.2 16.7 -1.3 41.7 Negligible
Devon County Council 28 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DT63 21.8 24.4 6.6 61.0 Slight Adverse
Assessment against 1-hour mean AQAL
A methodology is presented within LAQM.TG(09) to determine compliance with the hourly mean NO2 objective. This Guidance states that:
‘authorities may assume that exceedences of the 1-hour mean objective for NO2 are only likely to occur where annual mean concentrations are 60 µg/m3 or above’
As the predicted annual mean concentrations are below 60µg/m3, it can be assumed that the 1-hour mean NO2 AQAL will be met at these receptor locations.
6.1.2 PM10 Modelling Results
Table 6-2 presents the predicted impact at discrete receptor location in 2019 against the AQAL. The following comments on the results can be made:
• at all receptors the impact is considered to be negligible, in accordance with the stated assessment methodology;
• annual mean concentrations are predicted to be well below (i.e. less than 75%) the annual mean AQAL; and
• the number of 24-hour means above >50µg/m3 are predicted to be less than the objective of not more than 35 exceedences.
Table 6-2 Predicted Annual Mean PM10 Concentrations at Discrete Receptors
ID
Do Minimum Do Something Change as % of the annual
mean AQAL (%)
Do Something Concentration % of the annual mean AQAL (%)
Impact Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
DR1 14.1 0 15.3 0 2.9 38.2 Negligible
DR2 13.4 0 13.6 0 0.5 34.0 Negligible
DR3 13.8 0 14.0 0 0.3 34.9 Negligible
DR4 13.9 0 13.9 0 0.0 34.8 Negligible
DR5 14.6 0 14.7 0 0.2 36.7 Negligible
DR6 15.6 0 15.6 0 0.0 39.1 Negligible
DR7 16.6 1 16.9 1 0.9 42.4 Negligible
DR8 14.3 0 14.5 0 0.4 36.1 Negligible
DR9 15.0 0 14.7 0 -0.6 36.8 Negligible
DR10 15.3 0 15.8 0 1.3 39.5 Negligible
DR11 15.6 0 16.4 0 2.0 41.1 Negligible
DR12 14.9 0 14.6 0 -0.9 36.4 Negligible
DR13 14.1 0 15.8 0 4.4 39.5 Negligible
DR14 14.1 0 14.6 0 1.2 36.4 Negligible
DR15 14.0 0 14.2 0 0.4 35.4 Negligible
DR16 15.8 0 14.8 0 -2.6 37.0 Negligible
DR17 15.4 0 14.7 0 -1.9 36.7 Negligible
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ID
Do Minimum Do Something Change as % of the annual
mean AQAL (%)
Do Something Concentration % of the annual mean AQAL (%)
Impact Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
DR18 15.4 0 15.4 0 0.1 38.5 Negligible
DR19 17.0 1 17.2 1 0.5 42.9 Negligible
DR20 18.0 1 18.3 2 0.6 45.7 Negligible
DR21 18.1 1 18.3 2 0.6 45.8 Negligible
DR22 18.0 1 18.1 1 0.2 45.3 Negligible
DR23 16.3 0 16.3 0 0.2 40.8 Negligible
DR24 16.4 0 16.4 0 0.2 41.1 Negligible
DR25 15.2 0 15.3 0 0.2 38.3 Negligible
DR26 16.7 1 16.6 1 -0.3 41.5 Negligible
DR27 14.9 0 14.8 0 -0.2 36.9 Negligible
DR28 17.4 1 17.9 1 1.4 44.8 Negligible
DR29 18.6 2 18.4 2 -0.5 45.9 Negligible
DR30 17.2 1 17.1 1 -0.3 42.8 Negligible
DR31 16.6 1 16.5 0 -0.2 41.2 Negligible
DR32 16.9 1 16.7 1 -0.6 41.8 Negligible
DR33 16.9 1 16.8 1 -0.3 41.9 Negligible
DR34 16.6 1 16.4 0 -0.6 40.9 Negligible
DR35 16.3 0 16.2 0 -0.3 40.4 Negligible
DR36 16.2 0 16.2 0 -0.2 40.4 Negligible
DR37 17.3 1 17.1 1 -0.5 42.8 Negligible
DR38 13.1 0 13.1 0 0.0 32.8 Negligible
DR39 14.7 0 14.6 0 -0.3 36.5 Negligible
DR40 14.7 0 14.6 0 -0.3 36.4 Negligible
DR41 15.0 0 14.9 0 -0.3 37.3 Negligible
DR42 18.7 2 18.8 2 0.2 46.9 Negligible
DR43 14.5 0 14.5 0 0.1 36.4 Negligible
DR44 17.6 1 17.8 1 0.4 44.4 Negligible
DR45 15.1 0 15.0 0 -0.1 37.5 Negligible
DR46 13.5 0 13.4 0 -0.3 33.4 Negligible
DR47 17.2 1 17.0 1 -0.6 42.4 Negligible
DT3 20.3 4 20.1 3 -0.7 50.1 Negligible
DT6 19.5 3 19.8 3 0.8 49.5 Negligible
DT7 16.5 0 16.4 0 -0.3 40.9 Negligible
DT9 14.4 0 14.4 0 0.0 36.1 Negligible
DT16 16.5 1 16.4 0 -0.3 41.1 Negligible
DT18 15.0 0 15.1 0 0.2 37.7 Negligible
DT19 16.7 1 16.9 1 0.5 42.2 Negligible
DT23 18.3 2 18.5 2 0.6 46.3 Negligible
DT25 17.8 1 18.0 1 0.5 45.1 Negligible
DT32 17.5 1 18.0 1 1.3 45.0 Negligible
DT38 16.9 1 16.7 1 -0.3 41.8 Negligible
DT54 20.3 4 20.1 4 -0.5 50.3 Negligible
DT56 15.3 0 15.4 0 0.3 38.6 Negligible
DT58 17.1 1 17.0 1 -0.3 42.6 Negligible
Devon County Council 30 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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ID
Do Minimum Do Something Change as % of the annual
mean AQAL (%)
Do Something Concentration % of the annual mean AQAL (%)
Impact Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
DT63 18.0 1 18.4 2 0.9 45.9 Negligible
6.1.3 PM2.5 Annual Mean Modelling Results
Table 6-3 presents the predicted impact at discrete receptor location in 2019 against the 25µg/m3 Limit Value. The following comments on the results can be made:
• at all modelled receptors the impact is considered to be negligible, in accordance with the stated assessment methodology; and
• annual mean concentrations are predicted to be well below (i.e. less than 75% of the AQAL) the Limit Value.
Table 6-3 Predicted Annual Mean PM2.5 Concentrations at Discrete Receptors
ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DR1 9.1 9.8 2.7 24.5 Negligible
DR2 8.7 8.8 0.5 22.1 Negligible
DR3 9.0 9.0 0.3 22.6 Negligible
DR4 9.0 9.0 0.0 22.5 Negligible
DR5 9.0 9.1 0.2 22.7 Negligible
DR6 9.4 9.4 0.0 23.6 Negligible
DR7 10.0 10.2 0.8 25.4 Negligible
DR8 9.1 9.1 0.3 22.8 Negligible
DR9 9.4 9.3 -0.5 23.2 Negligible
DR10 9.6 9.9 1.1 24.8 Negligible
DR11 9.8 10.3 1.9 25.7 Negligible
DR12 9.4 9.2 -0.8 23.0 Negligible
DR13 8.9 9.9 4.0 24.8 Negligible
DR14 8.9 9.2 1.1 23.0 Negligible
DR15 8.9 9.0 0.3 22.4 Negligible
DR16 9.9 9.4 -2.4 23.4 Negligible
DR17 9.7 9.3 -1.7 23.1 Negligible
DR18 9.9 9.9 0.1 24.8 Negligible
DR19 10.8 10.9 0.4 27.3 Negligible
DR20 11.4 11.5 0.5 28.9 Negligible
DR21 11.4 11.5 0.5 28.8 Negligible
DR22 11.4 11.4 0.2 28.5 Negligible
DR23 10.4 10.4 0.2 26.0 Negligible
DR24 10.4 10.5 0.2 26.2 Negligible
DR25 9.8 9.8 0.2 24.6 Negligible
DR26 10.5 10.4 -0.3 26.1 Negligible
DR27 9.4 9.4 -0.2 23.5 Negligible
DR28 10.3 10.6 1.3 26.6 Negligible
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ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DR29 11.0 10.9 -0.5 27.1 Negligible
DR30 10.2 10.2 -0.2 25.4 Negligible
DR31 9.8 9.8 -0.1 24.5 Negligible
DR32 10.1 9.9 -0.5 24.8 Negligible
DR33 10.0 10.0 -0.2 24.9 Negligible
DR34 9.8 9.6 -0.5 24.1 Negligible
DR35 9.6 9.5 -0.3 23.8 Negligible
DR36 9.6 9.5 -0.2 23.8 Negligible
DR37 10.2 10.1 -0.5 25.2 Negligible
DR38 8.3 8.3 0.0 20.8 Negligible
DR39 9.2 9.2 -0.2 22.9 Negligible
DR40 9.2 9.2 -0.3 22.9 Negligible
DR41 9.5 9.4 -0.2 23.6 Negligible
DR42 12.0 12.0 0.2 30.0 Negligible
DR43 9.4 9.4 0.1 23.5 Negligible
DR44 11.0 11.1 0.4 27.8 Negligible
DR45 9.6 9.5 -0.1 23.8 Negligible
DR46 8.6 8.6 -0.2 21.5 Negligible
DR47 10.2 10.0 -0.6 25.0 Negligible
DT3 12.0 11.8 -0.6 29.6 Negligible
DT6 12.2 12.4 0.7 31.0 Negligible
DT7 10.4 10.3 -0.2 25.7 Negligible
DT9 9.3 9.4 0.0 23.4 Negligible
DT16 10.4 10.3 -0.3 25.8 Negligible
DT18 9.7 9.7 0.2 24.3 Negligible
DT19 10.6 10.7 0.4 26.9 Negligible
DT23 11.5 11.7 0.6 29.2 Negligible
DT25 11.3 11.4 0.5 28.4 Negligible
DT32 10.4 10.7 1.2 26.7 Negligible
DT38 10.6 10.5 -0.3 26.2 Negligible
DT54 12.0 11.9 -0.4 29.7 Negligible
DT56 9.8 9.9 0.2 24.8 Negligible
DT58 10.2 10.1 -0.2 25.3 Negligible
DT63 10.7 10.9 0.8 27.2 Negligible
6.1.4 Impact on Ecological Receptors
Critical Levels
The contribution of the scheme to critical levels for NOx at the roadside boundary of the SSSI’s is presented in Table 6-4 below. The contribution is small at less than 5% of the NOx Critical Level of 30µg/m3 at all the SSSIs and the total NOX concentration is predicted to be below the Critical Level at the all the SSSIs with the exception of Haldon Forest SSSI. The Critical Level at Haldon Forest SSSI adjacent to the A38 is exceeded in both the DM and DS scenarios and the scheme results in a 1.1µg/m3 increase, this is partially offset by a decrease at Haldon Forest SSSI adjacent to the A380 as the traffic distribution at this
Devon County Council 32 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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junction changes as a result of the scheme. The concentration will reduce (below those presented in the table) away from the roadside.
Table 6-4 Maximum Impacts on Oxides of Nitrogen Critical Levels
Name / Type
Defra Projected Back-ground
Road Contribution (µg/m3)
Concentration (µg/m3) Change
(µg/m3)
Change as % of Critical Level DM DS DM DS
Stover Park SSSI (Adj A32) 10.2 9.3 9.6 19.5 19.8 0.3 1%
Stover Park SSSI (Adj A38) 10.2 17.6 18.2 27.8 28.4 0.6 2%
Bovey Heathfield SSSI 10.4 10.5 10.9 21.0 21.3 0.3 1%
Chudleigh Knighton Heath SSSI 7.2 20.1 20.4 27.3 27.6 0.2 1%
7.2 20.1 20.4 27.3 27.6 0.2 1%
Chudleigh Caves & Woods SSSI 7.1 20.6 21.1 27.7 28.2 0.5 2%
Haldon Forest SSSI (Adj A38) 5.2 48.5 49.7 53.7 54.9 1.1 4%
5.2 48.5 49.7 53.7 54.9 1.1 4%
Haldon Forest SSSI (Adj A380) 5.1 25.0 24.8 30.2 29.9 -0.2 -1%
5.1 25.0 24.8 30.2 29.9 -0.2 -1%
Great Haldon Heaths SSSI 5.6 4.3 4.3 9.9 9.9 <0.1 <1%
Critical Loads
The contribution of the scheme to Critical Loads for nutrient nitrogen are presented in Table 6-5. The contribution is less than 1% of the lower and upper Critical Load ranges at all SSSIs, with the exception of the coniferous wood habitat at Chudleigh Caves & Woods SSSI and Haldon Forest SSSI (adjacent to the A38). The additional road contribution as a result of the scheme is 1.3% of the lower Critical Load at the SSSI habitat closest to the road. With increasing distance from the road the contribution will reduce further.
Table 6-5 Maximum Impacts on Critical Loads for Nutrient Nitrogen Deposition
Name / Type Habitat Change (kg
N/ha/yr)
Change as % of the Critical Level lower
range
Change as % of the Critical Level upper
range
Stover Park SSSI (Adj A382) Fen, marsh and swamp 0.048 0.5% 0.3%
Stover Park SSSI (Adj A38) Fen, marsh and swamp 0.033 0.3% 0.2%
Bovey Heathfield SSSI Fen, marsh and swamp 0.036 0.4% 0.2%
Chudleigh Knighton Heath SSSI Broad-leaved, mixed & yew woodland 0.069 0.7% 0.5%
Dwarf shrub heath 0.035 0.3% 0.2%
Chudleigh Caves & Woods SSSI Broadleaved deciduous woodland 0.066 0.7% 0.3%
Haldon Forest SSSI (Adj A38) Coniferous woodland 0.063 1.3% 0.4%
Dwarf shrub heath 0.032 0.3% 0.2%
Haldon Forest SSSI (Adj A380) Coniferous woodland 0.063 1.3% 0.4%
Dwarf shrub heath 0.032 0.3% 0.2%
Great Haldon Heaths SSSI Fen, marsh and swamp 0.033 0.3% 0.2%
The process contribution to acid Critical Load functions is presented in Table 6-6 below. The process contribution as a percentage of the Critical Load function has been calculated according to the formulae in Section 3.3.3. The contribution remains below 1% at all SSSIs.
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Table 6-6 Maximum Impacts on Critical Loads for Acid Deposition
Name / Type Habitat Change
(N kgeq/ha/yr)
Contribution as a % of the
Critical Load Function
Stover Park SSSI (Adj A382) Fen, marsh and swamp 0.003 0.5%
Stover Park SSSI (Adj A38) Fen, marsh and swamp 0.002 0.3%
Bovey Heathfield SSSI Fen, marsh and swamp 0.003 0.4%
Chudleigh Knighton Heath SSSI Broad-leaved, mixed and yew woodland 0.005 0.1%
Dwarf shrub heath 0.002 0.1%
Chudleigh Caves & Woods SSSI Broadleaved deciduous woodland 0.005 <0.1%
Haldon Forest SSSI (Adj A38) Coniferous woodland 0.005 0.2%
Dwarf shrub heath 0.002 <0.1%
Haldon Forest SSSI (Adj A380) Coniferous woodland 0.005 0.2%
Dwarf shrub heath 0.002 <0.1%
Great Haldon Heaths SSSI Fen, marsh and swamp 0.002 0.4%
6.2 2034 Design Year
6.2.1 Nitrogen Dioxide Annual Mean Modelling Results
Assessment against annual mean AQAL
Table 6-7 presents the predicted impact at discrete receptor location in 2034 against the annual mean AQAL of 40µg/m3. The following comments on the results can be made:
• at the majority of receptors the impact is considered to be negligible, in accordance with the stated assessment methodology;
• moderate adverse impacts are predicted at receptors DR1, DR11, and DR13 due to their proximity to the scheme and predicted percentage change of the AQAL. However the concentration at these receptors with the scheme remains less than 75% of the AQAL; and
• negligible impacts are predicted at the majority of modelled receptors within the AQMAs with slight adverse impacts predicted at receptor DT6 on Queens Street, however concentrations at this location are predicted to be less than 80% of the AQAL.
Figure A-5 and Figure A-6 (Appendix A) present the concentration isopleths across the scheme area for the DM and DS scenario respective.
Table 6-7 Predicted Annual Mean NO2 Concentrations at Discrete Receptors
ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DR1 10.9 16.6 14.5 41.6 Moderate Adverse
DR2 7.4 8.1 1.7 20.2 Negligible
DR3 9.0 8.7 -0.6 21.9 Negligible
DR4 9.1 8.6 -1.3 21.5 Negligible
DR5 8.5 8.2 -0.7 20.6 Negligible
DR6 8.5 8.4 -0.2 21.0 Negligible
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ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DR7 11.5 12.1 1.5 30.2 Negligible
DR8 8.0 8.5 1.2 21.2 Negligible
DR9 10.2 9.2 -2.4 23.1 Negligible
DR10 11.4 12.5 2.9 31.4 Negligible
DR11 12.5 18.7 15.6 46.9 Moderate Adverse
DR12 9.9 9.5 -1.0 23.8 Negligible
DR13 7.2 12.4 13.0 31.1 Moderate Adverse
DR14 7.4 8.9 3.7 22.2 Negligible
DR15 7.1 7.6 1.4 19.1 Negligible
DR16 15.8 12.0 -9.3 30.1 Negligible
DR17 11.5 9.6 -4.8 24.0 Negligible
DR18 17.6 17.9 0.9 44.9 Negligible
DR19 21.9 22.5 1.5 56.2 Negligible
DR20 26.0 26.8 1.9 66.9 Negligible
DR21 21.6 21.8 0.5 54.6 Negligible
DR22 24.3 24.5 0.6 61.3 Negligible
DR23 18.2 18.4 0.4 46.0 Negligible
DR24 18.9 18.8 -0.3 46.9 Negligible
DR25 12.5 12.6 0.2 31.5 Negligible
DR26 17.6 17.0 -1.4 42.6 Negligible
DR27 12.3 11.7 -1.5 29.3 Negligible
DR28 15.8 17.0 3.1 42.6 Negligible
DR29 19.2 18.2 -2.5 45.4 Negligible
DR30 14.8 14.2 -1.4 35.5 Negligible
DR31 12.3 11.5 -2.0 28.7 Negligible
DR32 13.7 14.1 0.9 35.2 Negligible
DR33 14.6 14.2 -0.9 35.5 Negligible
DR34 10.4 10.7 0.9 26.8 Negligible
DR35 9.5 9.7 0.5 24.2 Negligible
DR36 9.6 9.4 -0.6 23.4 Negligible
DR37 13.0 12.2 -1.9 30.6 Negligible
DR38 7.1 6.3 -2.2 15.7 Negligible
DR39 9.1 8.8 -0.8 22.0 Negligible
DR40 9.1 8.7 -0.8 21.9 Negligible
DR41 8.6 8.3 -0.8 20.6 Negligible
DR42 23.3 23.6 0.6 58.9 Negligible
DR43 9.5 9.7 0.5 24.2 Negligible
DR44 18.5 19.1 1.5 47.9 Negligible
DR45 14.7 14.6 -0.3 36.4 Negligible
DR46 7.5 7.0 -1.1 17.5 Negligible
DR47 11.1 10.4 -1.8 25.9 Negligible
DT3 24.1 22.9 -3.1 57.2 Negligible
DT6 30.3 31.3 2.4 78.2 Slight Adverse
DT7 16.8 16.3 -1.3 40.8 Negligible
DT9 10.8 10.8 -0.2 26.9 Negligible
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ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DT16 17.0 16.5 -1.3 41.1 Negligible
DT18 12.5 12.4 -0.2 31.1 Negligible
DT19 20.5 21.0 1.4 52.6 Negligible
DT23 26.6 27.4 2.0 68.6 Negligible
DT25 21.4 21.7 0.6 54.1 Negligible
DT32 16.3 17.3 2.7 43.4 Negligible
DT38 18.0 17.4 -1.5 43.5 Negligible
DT54 25.3 24.3 -2.7 60.6 Negligible
DT56 13.8 13.7 -0.3 34.2 Negligible
DT58 14.8 14.4 -0.9 36.0 Negligible
DT63 18.0 18.6 1.5 46.5 Negligible
Assessment against 1-hour mean AQAL
As the predicted annual mean concentrations are below 60µg/m3, it can be assumed that the 1-hour mean NO2 AQAL will be met at these receptor locations.
6.2.2 PM10 Modelling Results
Table 6-8 presents the predicted impact at discrete receptor location in 2034 against the AQALs. The following comments on the results can be made:
• at the majority of receptors the impact is considered to be negligible, in accordance with the stated assessment methodology, with a slight adverse impact at DR13 (close to the roundabout on the on the Jetty Marsh Link road). However the concentration is predicted to be less than 40% of the AQAL;
• annual mean concentrations are predicted to be well below (i.e. less than 75%) the annual mean AQAL; and
• the number of 24-hour means above >50µg/m3 are predicted to remain less than the objective of not more than 35 exceedences.
Table 6-8 Predicted Annual Mean PM10 Concentrations at Discrete Receptors
ID
Do Minimum Do Something Change as % of the annual
mean AQAL (%)
Do Something Concentration % of the annual mean AQAL (%)
Impact Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
DR1 14.1 0 15.6 0 3.5 38.9 Negligible
DR2 13.3 0 13.6 0 0.7 33.9 Negligible
DR3 13.9 0 14.0 0 0.5 35.1 Negligible
DR4 13.9 0 14.0 0 0.1 35.0 Negligible
DR5 14.6 0 14.8 0 0.3 36.9 Negligible
DR6 15.8 0 16.0 0 0.3 39.9 Negligible
DR7 16.9 1 17.6 1 1.7 44.0 Negligible
DR8 14.3 0 14.5 0 0.6 36.3 Negligible
DR9 15.1 0 14.9 0 -0.5 37.2 Negligible
DR10 15.5 0 16.3 0 2.1 40.8 Negligible
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ID
Do Minimum Do Something Change as % of the annual
mean AQAL (%)
Do Something Concentration % of the annual mean AQAL (%)
Impact Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
DR11 16.0 0 17.0 1 2.5 42.6 Negligible
DR12 14.8 0 14.7 0 -0.3 36.8 Negligible
DR13 13.9 0 15.9 0 5.1 39.8 Slight Adverse
DR14 14.0 0 14.5 0 1.4 36.3 Negligible
DR15 13.9 0 14.1 0 0.5 35.2 Negligible
DR16 16.0 0 15.1 0 -2.3 37.6 Negligible
DR17 15.5 0 14.7 0 -2.0 36.8 Negligible
DR18 15.4 0 15.4 0 0.2 38.6 Negligible
DR19 17.7 1 17.9 1 0.5 44.6 Negligible
DR20 19.3 3 19.5 3 0.4 48.7 Negligible
DR21 18.3 2 18.4 2 0.3 46.0 Negligible
DR22 18.7 2 18.8 2 0.2 46.9 Negligible
DR23 16.5 1 16.6 1 0.2 41.5 Negligible
DR24 16.8 1 16.8 1 0.1 41.9 Negligible
DR25 15.3 0 15.3 0 0.1 38.2 Negligible
DR26 16.8 1 16.7 1 -0.5 41.7 Negligible
DR27 15.0 0 14.8 0 -0.5 36.9 Negligible
DR28 18.2 2 18.5 2 0.7 46.2 Negligible
DR29 20.1 4 19.7 3 -0.9 49.3 Negligible
DR30 18.3 2 18.1 1 -0.6 45.2 Negligible
DR31 17.2 1 17.0 1 -0.6 42.4 Negligible
DR32 17.5 1 17.6 1 0.2 44.1 Negligible
DR33 17.6 1 17.5 1 -0.3 43.8 Negligible
DR34 17.0 1 17.1 1 0.3 42.7 Negligible
DR35 16.6 1 16.7 1 0.2 41.7 Negligible
DR36 16.7 1 16.6 1 -0.2 41.4 Negligible
DR37 18.2 2 17.9 1 -0.8 44.7 Negligible
DR38 13.6 0 13.3 0 -0.7 33.3 Negligible
DR39 14.9 0 14.7 0 -0.3 36.8 Negligible
DR40 14.8 0 14.7 0 -0.4 36.7 Negligible
DR41 15.2 0 15.1 0 -0.3 37.7 Negligible
DR42 19.5 3 19.5 3 0.2 48.9 Negligible
DR43 14.5 0 14.6 0 0.2 36.4 Negligible
DR44 17.9 1 18.2 2 0.7 45.4 Negligible
DR45 15.3 0 15.2 0 -0.2 38.0 Negligible
DR46 13.5 0 13.4 0 -0.4 33.4 Negligible
DR47 18.0 1 17.7 1 -0.8 44.3 Negligible
DT3 22.7 7 22.1 7 -1.3 55.3 Negligible
DT6 21.3 5 21.5 5 0.5 53.7 Negligible
DT7 16.6 1 16.4 0 -0.4 41.0 Negligible
DT9 14.4 0 14.4 0 0.0 36.0 Negligible
DT16 16.6 1 16.5 0 -0.4 41.2 Negligible
DT18 15.0 0 15.1 0 0.1 37.7 Negligible
DT19 17.4 1 17.6 1 0.5 44.0 Negligible
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ID
Do Minimum Do Something Change as % of the annual
mean AQAL (%)
Do Something Concentration % of the annual mean AQAL (%)
Impact Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
Annual Mean (µg/m3)
No. of 24hr means
>50µg/m3
DT23 19.6 3 19.7 3 0.4 49.4 Negligible
DT25 18.1 1 18.2 2 0.3 45.4 Negligible
DT32 18.4 2 18.6 2 0.6 46.5 Negligible
DT38 17.0 1 16.8 1 -0.5 42.0 Negligible
DT54 22.6 7 22.1 7 -1.2 55.4 Negligible
DT56 15.4 0 15.4 0 0.1 38.6 Negligible
DT58 18.2 2 18.0 1 -0.4 45.1 Negligible
DT63 19.1 2 19.2 3 0.2 48.1 Negligible
6.2.3 PM2.5 Annual Mean Modelling Results
Table 6-9 presents the predicted impact at discrete receptor location in 2019 against the 25µg/m3 Limit Value. The following comments on the results can be made:
• at all modelled receptors the impact is considered to be negligible, in accordance with the stated assessment methodology; and
• annual mean concentrations are predicted to be well below the AQAL.
Table 6-9 Predicted Annual Mean PM2.5 Concentrations at Discrete Receptors
ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DR1 8.9 9.7 3.0 24.3 Negligible
DR2 8.5 8.6 0.6 21.6 Negligible
DR3 8.8 8.9 0.4 22.2 Negligible
DR4 8.8 8.9 0.1 22.1 Negligible
DR5 8.9 8.9 0.2 22.4 Negligible
DR6 9.3 9.4 0.3 23.5 Negligible
DR7 9.9 10.3 1.5 25.7 Negligible
DR8 8.8 9.0 0.5 22.5 Negligible
DR9 9.3 9.2 -0.4 22.9 Negligible
DR10 9.5 9.9 1.7 24.9 Negligible
DR11 9.8 10.3 2.1 25.8 Negligible
DR12 9.2 9.1 -0.3 22.7 Negligible
DR13 8.7 9.7 4.3 24.4 Negligible
DR14 8.7 9.0 1.2 22.5 Negligible
DR15 8.6 8.8 0.4 21.9 Negligible
DR16 9.8 9.3 -2.0 23.2 Negligible
DR17 9.5 9.1 -1.7 22.7 Negligible
DR18 9.7 9.8 0.2 24.4 Negligible
DR19 10.9 11.0 0.4 27.6 Negligible
DR20 11.8 11.9 0.4 29.8 Negligible
DR21 11.2 11.3 0.3 28.2 Negligible
DR22 11.4 11.5 0.2 28.7 Negligible
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ID Do Minimum
(µg/m3) Do Something
(µg/m3)
Change as a Percentage of the
AQAL (%)
Do Something Concentration as Percentage of the
AQAL (%)
Impact
DR23 10.3 10.3 0.1 25.8 Negligible
DR24 10.4 10.4 <0.1 26.1 Negligible
DR25 9.6 9.6 0.1 24.1 Negligible
DR26 10.3 10.2 -0.4 25.5 Negligible
DR27 9.3 9.2 -0.4 23.0 Negligible
DR28 10.5 10.6 0.6 26.5 Negligible
DR29 11.5 11.3 -0.8 28.2 Negligible
DR30 10.5 10.4 -0.5 26.0 Negligible
DR31 9.9 9.8 -0.5 24.5 Negligible
DR32 10.1 10.2 0.2 25.4 Negligible
DR33 10.2 10.1 -0.2 25.3 Negligible
DR34 9.7 9.8 0.2 24.4 Negligible
DR35 9.5 9.6 0.1 23.9 Negligible
DR36 9.5 9.5 -0.2 23.7 Negligible
DR37 10.4 10.2 -0.6 25.5 Negligible
DR38 8.4 8.3 -0.6 20.8 Negligible
DR39 9.1 9.0 -0.3 22.6 Negligible
DR40 9.1 9.0 -0.3 22.6 Negligible
DR41 9.4 9.3 -0.3 23.3 Negligible
DR42 12.1 12.1 0.2 30.2 Negligible
DR43 9.2 9.2 0.2 23.0 Negligible
DR44 10.9 11.1 0.6 27.6 Negligible
DR45 9.5 9.4 -0.2 23.6 Negligible
DR46 8.5 8.4 -0.3 21.1 Negligible
DR47 10.3 10.2 -0.7 25.4 Negligible
DT3 12.8 12.5 -1.1 31.4 Negligible
DT6 12.9 13.0 0.5 32.4 Negligible
DT7 10.2 10.1 -0.4 25.2 Negligible
DT9 9.2 9.2 0.0 22.9 Negligible
DT16 10.2 10.1 -0.4 25.2 Negligible
DT18 9.5 9.5 0.1 23.8 Negligible
DT19 10.8 10.9 0.4 27.3 Negligible
DT23 12.0 12.1 0.4 30.1 Negligible
DT25 11.1 11.2 0.2 27.9 Negligible
DT32 10.5 10.7 0.5 26.7 Negligible
DT38 10.4 10.3 -0.4 25.7 Negligible
DT54 12.8 12.6 -1.0 31.4 Negligible
DT56 9.7 9.7 0.1 24.3 Negligible
DT58 10.4 10.4 -0.3 25.9 Negligible
DT63 11.0 11.0 0.2 27.5 Negligible
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6.2.4 Impact on Ecological Receptors
Critical Levels
The contribution of the scheme to Critical Levels for NOx at the roadside boundary of the SSSIs is presented in Table 6-10 below. The contribution is small at less than 4% of the Critical Level of 30µg/m3 at all the SSSIs and the total NOX concentration is predicted to be below the Critical Level at the all the SSSIs with the exception of Haldon Forest SSSI. The Critical Level at Haldon Forest SSSI adjacent to the A38 is exceeded in both the DM and DS scenarios and the scheme results in a 0.8µg/m3 increase, this is partially offset by a 0.4µg/m3 decrease Haldon Forest SSSI adjacent to the A380 as the traffic distribution at this junction changes as a result of the scheme. The concentration will reduce (below those presented in the table) away from the roadside.
Table 6-10 Maximum Impacts on Nitrogen Oxide Critical Levels
Name / Type
Defra Projected Back-ground
Road Contribution (µg/m3)
Concentration (µg/m3) Change
(µg/m3)
Change as % of Critical Level DM DS DM DS
Stover Park SSSI (Adj A32) 10.1 6.6 6.8 16.7 16.9 0.2 1%
Stover Park SSSI (Adj A38) 10.1 12.5 12.9 22.6 23.0 0.4 1%
Bovey Heathfield SSSI 10.5 6.7 7.1 17.3 17.6 0.3 1%
Chudleigh Knighton Heath SSSI 6.8 14.3 14.4 21.1 21.3 0.1 <1%
6.8 14.3 14.4 21.1 21.3 0.1 <1%
Chudleigh Caves & Woods SSSI 6.6 13.8 14.2 20.4 20.8 0.4 1%
Haldon Forest SSSI (Adj A38) 4.8 31.0 31.7 35.8 36.6 0.8 3%
4.8 31.0 31.7 35.8 36.6 0.8 3%
Haldon Forest SSSI (Adj A380) 4.8 16.2 15.8 21.0 20.6 -0.4 -1%
4.8 16.2 15.8 21.0 20.6 -0.4 -1%
Great Haldon Heaths SSSI 5.3 2.9 2.8 8.2 8.1 -0.1 <1%
Critical Loads
The contribution of the scheme to Critical Loads for nutrient N are presented in Table 6-11. The contribution is less than 1% of the lower and upper Critical Load ranges at all SSSIs. With increasing distance from the road the contribution will reduce further.
Table 6-11 Maximum Impacts on Critical Loads for Nutrient Nitrogen Deposition
Name / Type Habitat Change (kg
N/ha/yr)
Change as % of the Critical Level lower
range
Change as % of the Critical Level upper
range
Stover Park SSSI (Adj A382) Fen, marsh and swamp 0.032 0.3% 0.2%
Stover Park SSSI (Adj A38) Fen, marsh and swamp 0.023 0.2% 0.2%
Bovey Heathfield SSSI Fen, marsh and swamp 0.024 0.2% 0.2%
Chudleigh Knighton Heath SSSI Broad-leaved, mixed & yew woodland 0.049 0.5% 0.3%
Dwarf shrub heath 0.024 0.2% 0.1%
Chudleigh Caves & Woods SSSI Broadleaved deciduous woodland 0.043 0.4% 0.2%
Haldon Forest SSSI (Adj A38) Coniferous woodland 0.046 0.9% 0.3%
Devon County Council 40 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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Name / Type Habitat Change (kg
N/ha/yr)
Change as % of the Critical Level lower
range
Change as % of the Critical Level upper
range
Dwarf shrub heath 0.023 0.2% 0.1%
Haldon Forest SSSI (Adj A380) Coniferous woodland 0.043 0.9% 0.3%
Dwarf shrub heath 0.022 0.2% 0.1%
Great Haldon Heaths SSSI Fen, marsh and swamp 0.023 0.2% 0.2%
The process contribution to acid Critical Load functions is presented in Table 6-12 below. The process contribution as a percentage of the Critical Load function has been calculated according to the formulae in Section 3.3.3. The contribution remains below 1% at all SSSIs.
Table 6-12 Maximum Impacts on Critical Loads for Acid Deposition
Name / Type Habitat Change
(N kgeq/ha/yr)
Contribution as a % of the
Critical Load Function
Stover Park SSSI (Adj A382) Fen, marsh and swamp 0.002 0.3%
Stover Park SSSI (Adj A38) Fen, marsh and swamp 0.002 0.2%
Bovey Heathfield SSSI Fen, marsh and swamp 0.002 0.2%
Chudleigh Knighton Heath SSSI Broad-leaved, mixed and yew woodland 0.003 0.1%
Dwarf shrub heath 0.002 0.1%
Chudleigh Caves & Woods SSSI Broadleaved deciduous woodland 0.003 <0.1%
Haldon Forest SSSI (Adj A38) Coniferous woodland 0.003 0.2%
Dwarf shrub heath 0.002 <0.1%
Haldon Forest SSSI (Adj A380) Coniferous woodland 0.003 0.2%
Dwarf shrub heath 0.002 <0.1%
Great Haldon Heaths SSSI Fen, marsh and swamp 0.002 0.3%
6.3 Sensitivity Assessment Results
The sensitivity assessment results are presented in Appendix D and investigate the sensitivity of the predictions to the following model inputs
a) projected emissions factors; and b) projected backgrounds.
The sensitivity assessment focuses on annual mean NO2 concentrations given the documented uncertainty in emission factors and the low level of predicted particulate concentrations in relation to the AQAL; the findings are discussed in the sections below.
6.3.1 2019 Sensitivity Assessment
The concentration at all receptors is increased in comparison to the non-sensitivity scenarios presented in the main body of the report upon which the impact assessment is based. The impact at the majority of modelled receptors remains negligible, however as a result of larger increases or decreases resulting from use of the un-projected emission factors there is an increase in the number of receptors at which adverse impacts are predicted, and a beneficial impact predicted at one location.
Devon County Council 41 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment DRAFT - August 2015
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In the absence of the projected improvement in vehicle emissions or background NO2 concentrations, the projected increase in traffic flow in the DM scenario is predicted to lead to exceedences of the annual mean AQAL on Queen Street (locations DR20, DT6, and DT23), Station Rd (DR21), Torquay Rd (DR22) and adjacent to the A38 (DR42). The increased traffic as a result of the DS scenario increases the concentration further. At DT6 whilst the increase as a result of the scheme is small at less than 2µg/m3, the concentration is >110% of the AQAL; any increase >1% of the AQAL is considered a substantial adverse impact at locations that are 110% of the AQAL (i.e. 44µg/m3) by the IAQM guidance. It should be noted that the verification factor applied results in an over-prediction (of +17%) at DT6 compared to measured concentrations.
Concentrations approaching the AQAL (>36µg/m3) are predicted at Station Rd (DT25) and at Gestridge Rd (DT3 and DT54). The impact of the DS scenario is considered, moderate adverse at DT25, negligible at DT3 and slight beneficial at DT54.
6.3.2 2034 Sensitivity Assessment
As with the 2019 sensitivity assessment, the concentration at all receptors is increased in comparison to the non-sensitivity scenarios. The impact at the majority of modelled receptors however remains unchanged at negligible impact, with the following exceptions:
• the sensitivity assessment results in the impact increasing at DR14, DR20, DT23 from negligible to slight adverse with concentrations well below the AQAL; and
• The concentration at DT6 (Queen Street) is above the AQAL in both the DM and DS scenarios. The DT6 changes from a slight adverse to moderate adverse impact given the overall concentration however the increase as a result of the scheme remains small at less than 2µg/m3.
6.4 Significance of Local Air Quality Impacts
The EPUK and IAQM15 guidance considers a number of factors in the determination of significance of predicted air quality impacts. Such factors include:
• the existing and future air quality in the absence of the development;
• the extent of current and future population exposure to the impacts;
• the worst case assumptions adopted when undertaking the prediction of impacts; and
• the extent to which the proposed development has adopted best practice to eliminate and minimise emissions.
The scheme is considered not to lead to a significant impact on air quality for the following reasons:
• the impacts on annual mean PM10 and PM2.5 and 24-hour mean PM10 concentrations across the study area is considered negligible;
• the scheme does not lead to any exceedances of AQALs at receptors adjacent or in close proximity to the scheme and concentrations are predicted to remain significantly below the AQAL;
• the scheme does not result in any new area of exceedances of AQALs;
• the increases in annual mean NO2 concentrations in the AQMA, specifically the Queen Street area, and Station Road/Torquay Rd area are small (less than 5% of the AQAL) and therefore not considered to result in a significant worsening of air quality. The
15
Environmental Protection UK and Institute of Air Quality Management, ‘Land-Use Planning and Development Control: Planning for Air Quality', 2015.
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small increases in this area are partially off-set by predicted improvements in air quality in Kingsteignton area of the AQMA; and
• the sensitivity assessment indicates that the scheme would not result in any new exceedances of AQALs over the DM scenario.
With respect to impacts on designated habitats:
• increases in nutrient N and acid deposition are less than 1% of the Critical Loads and not considered to represent a significant increase; and
• increases in NOx are small and not anticipated to lead to exceedences of Critical Levels with the exception of Haldon Forest adjacent to the A38 (which is discussed below).
The baseline NOx concentrations at Haldon Forest adjacent to the A38 exceeds the Critical Level of 30µg/m3 in the baseline year with a concentration of 53µg/m3
. The concentration is predicted to be above the Critical Level in both DM future scenarios in areas close to the roadside. The SSSI Units adjacent to the A38 are 112 (Oxencombe Brooke) and 113 (Race Course), the latest condition reports from Natural England16 for these units report them both as ‘favourable’ with ‘no identified condition threat’. The DS scenarios will not significantly alter the situation with a concentration of 54.9µg/m3 in 2019 and 36.6µg/m3 in 2034, as such it is considered unlikely there would be a significant effect as a result of the scheme.
6.5 WebTAG Local Air Quality Results
The WebTAG local air quality assessment summary results are presented in Table 6-13 and Table 6-14 for 2019 and 2034, respectively. The results show a net decrease in NO2 exposure for both 2019 and 2034. In the case of exposure to PM10, a net decrease is predicted in 2019 with a net increase in 2034. In all cases the changes are less than 0.5% of the DM scenario.
Table 6-13 Worksheet 1b Local Air Quality – 2019 Summary
PM10 NO2
Total properties across all routes (DM) 8179 8179
Total properties across all routes (DS) 8179 8179
Do-minimum assessment across all routes(I) 119184 85054
Do-something assessment across all routes (II) 119155 84797
Net total assessment, all routes (II-I) -29 -257
Number of properties with an improvement 4160 4311
Number of properties with no change 0 146
Number of properties with a deterioration 4019 3722
16
https://designatedsites.naturalengland.org.uk/SiteUnitList.aspx?SiteCode=S1005936&SiteName=haldon&countyCode=&responsiblePerson=
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Table 6-14 Worksheet 1b Local Air Quality – 2034 Summary
PM10 NO2
Total properties across all routes (DM) 8179 8179
Total properties across all routes (DS) 8179 8179
Do-minimum assessment across all routes(I) 119103 76791
Do-something assessment across all routes (II) 119107 76775
Net total assessment, all routes (II-I) 4 -16
Number of properties with an improvement 3629 3700
Number of properties with no change 0 385
Number of properties with a deterioration 4550 4094
The TAG ‘Air Quality Valuation Workbook’ has been completed alongside this assessment to calculate the economic valuation of changes in air quality in order to inform the overall cost-benefit analysis (CBA) in the transport appraisal of the proposed scheme. The CBA entails presenting as many of the impacts of a scheme or option as possible in monetary terms, so that they can be compared in a common unit of measurement.
6.6 Regional Air Quality Impact
Table 6-15 below present the emissions from the affected road network (based on regional screening criteria) for the assessment scenarios. The scheme is predicted to result in:
• a decrease in emissions in the 2019, with the exception of NOx and PM10 in which a minor increase is predicted; and
• a decrease in emissions in 2034 with a minor increase in NOx.
Table 6-15 Regional Emissions (tonnes/yr)
Pollutant 2014 2019 DM 2019 DS Change (%) 2034 DM 2034 DS Change (%)
CO 54.3 77.2 71.3 -7.6% 119.3 111.4 -6.7%
THC 6.0 8.6 7.8 -9.5% 13.2 12.2 -7.8%
NOx 14.4 19.3 19.8 2.7% 30.6 30.8 0.7%
PM10 0.6 0.8 0.9 0.5% 1.4 1.4 -3.0%
C 2,861.7 3,830.6 3,796.7 -0.9% 6,091.8 5,913.4 -2.9%
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7.0 MITIGATION MEASURES
This section presents mitigation measures required during the construction and operational phases of the development in order to reduce the potential impact.
7.1 Construction Phase Mitigation
In order to control potential impacts, the mitigation measures presented within Table 7-1 are proposed. With the effective application of the dust mitigation measures it is considered that the impacts at all receptors will be ‘not significant’.
Table 7-1 Construction Dust Mitigation Measures
Site Application Mitigation Measure
Communications
Develop and implement a stakeholder communications plan that includes community engagement before work commences on site.
Display the name and contact details of person(s) accountable for air quality and dust issues on the site boundary.
Display the head or regional office contact information
General dust management
Develop and implement a dust management plan (DMP)
Record all dust and air quality complaints and take appropriate measures to reduce emissions
Record any exceptional; incidents that cause dust off site.
Carry out regular site inspections to monitor compliance with the DMP, record inspection results, and make an inspection log available to the local authority when asked
Ensure an adequate supply of water is available onsite for effective dust suppression
Increase the frequency of site inspections by the person accountable for air quality and dust issues on site when activities with a high potential to produce dust are being carried out and during prolonged dry or windy conditions
Minimise drop heights from loading shovels and other material handling equipment
Impose a site speed limit of 10mph on unpaved haul roads
Ensure all vehicles engines are switched off when stationary
Plan site layout so machinery is located away from receptors as far as possible
Avoid site runoff of water or mud
In close proximity to sensitive receptors erect solid screens or barriers around dusty activities or the site boundary that are at least as high as any stockpiles.
Keep site fencing and barriers using wet methods
Remove materials that have a potential to produce dust from site as soon as possible, unless being re-used on site.
In close proximity to sensitive receptors cover or fence stockpiles to prevent wind whipping
Demolition Ensure water suppression is used as required during removal of existing road surfaces operations.
Earthworks
Re-vegetate earthworks and soil stockpiles to stabilise surfaces as soon as practicable
Avoid double handling of material where possible
Cease operations during high winds in the direction of sensitive receptors
Construction Ensure aggregates are stored in bunded areas and are not allowed to dry out, unless this is required for a particular process, in which case ensure that appropriate additional control measures are in place.
Trackout
Use water assisted dust sweepers on the access and local roads to removed tracked out material is necessary
Avoid dry sweeping large areas
Implement wheel washing system as required
Ensure vehicles entering and leaving sites are covered to prevent escape of materials during transport.
Inspect on-site haul routes for integrity and instigate necessary repairs to the surface as soon as reasonably practicable.
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Site Application Mitigation Measure
Access areas to be located at least 10m from receptors where possible
7.2 Operational Phase Road Traffic Emissions
The scheme has incorporated a number of mitigation measures that have not been quantitatively assessed. However the influence of these measures is discussed in broad terms below:
• the road design incorporates best practice measures to encourage traffic to flow freely and reduce stop-start traffic. Emissions from road sources typically increase as a result of congestion (that increases the time vehicles are idling in a particular location) or stop/start driving (that may encourage heavy acceleration). Measures to increase free traffic flow include, building sufficient capacity on the network, turning lanes, roundabouts, and effective sight lines.
• the inclusion of a Cycle Path in the scheme encourages a sustainable form of transport. Transport measures that may reduce the number of cars on the road network and result in people using zero-emission modes of transport will benefit air quality in the local and wider area.
The impact on receptors adjacent to the scheme is not predicted to be significant and as such further mitigation measures along the scheme length are not required.
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8.0 CONCLUSIONS
The conclusions of the assessment are as follows:
• with respect to the construction phase, areas of the scheme in close proximity to large numbers of sensitive receptors, in particular the Stover School and at the A382 / Jetty Marsh Link II roundabout are considered to have a potentially high risk of causing dust impacts in the absence of mitigation. With the effective implementation of the defined mitigation measures however, the impacts are considered to be not significant at receptors;
• the operational phase of the scheme is considered not to lead to a significant impact on air quality for the following reasons:
o the impacts on annual mean PM10 and PM2.5 and 24-hour mean PM10 concentrations across the study area is considered negligible;
o the scheme does not lead to any exceedances of AQALs at receptors adjacent or in close proximity to the scheme and concentrations are predicted to remain significantly below the AQAL;
o the scheme does not result in any new area of exceedances of AQALs; o increases in annual mean NO2 concentrations in the AQMA, specifically the
Queen Street area, and Station Road/Torquay Rd area are small (less than 5% of the AQAL) and therefore not considered to result in a significant worsening of air quality. The small increases in this area are partially off-set by predicted improvements in air quality in Kingsteignton area of the AQMA; and
o the sensitivity assessment indicates that the scheme would not result in any new exceedances of AQALs over the Do Minimum scenario.
• although not quantitatively assessed the scheme includes measures that would reduce potential impacts on air quality including road design to encourage free flow of traffic and a Cycle Path.
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9.0 CLOSURE
This report has been prepared by SLR Consulting Limited with all reasonable skill, care and diligence, and taking account of the manpower and resources devoted to it by agreement with the client. Information reported herein is based on the interpretation of data collected and has been accepted in good faith as being accurate and valid.
This report is for the exclusive use of Devon County Council; no warranties or guarantees are expressed or should be inferred by any third parties. This report may not be relied upon by other parties without written consent from SLR.
SLR disclaims any responsibility to the client and others in respect of any matters outside the agreed scope of the work.
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APPENDIX A FIGURES
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Figure A-1
Modelled Receptor and Diffusion Tube Locations
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Figure A-2
Assessed Designated Habitats
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Figure A-3
2019 DM Scenario: NO2 Annual Mean Concentration
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