table 5-1 potential dust emission magnitude · 2016-09-15 · construction material, i.e....

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


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



Area 3


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



Area 4


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



Area 5


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



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Activity Comments Dust Emission Magnitude


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


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



Low

Ecological Impacts

There are no designated ecological habitats adjacent to this area N/A

Area 3


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



Low

Ecological Impacts


Area 4


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


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Sensitivity to: Comments Sensitivity

Impacts 20m

Ecological Impacts


Area 5


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



Low

Ecological Impacts


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


Area 2 Sensitivity

Dust Soiling Impacts Low Low Risk Low Risk Low Risk Low Risk


Ecological Impacts N/A N/A N/A N/A N/A


Area 3 Sensitivity

Dust Soiling Impacts High Medium Risk Medium Risk Medium Risk High Risk




Area 4 Sensitivity




Magnitude : Medium Large Medium Large

Area 5 Sensitivity





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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.


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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


DR12 12.2 10.6 -4.0 26.6 Negligible


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


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ID Do Minimum


(µg/m3)


AQAL (%)


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




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


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


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


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ID Do Minimum


(µg/m3)


AQAL (%)


AQAL (%)

Impact


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


mean AQAL (%)



No. of 24hr means

>50µg/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


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ID


mean AQAL (%)



No. of 24hr means

>50µg/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)


AQAL (%)


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)


AQAL (%)


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


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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%


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%


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%




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%


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%



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)


AQAL (%)


AQAL (%)

Impact


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)


AQAL (%)


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


DR12 9.9 9.5 -1.0 23.8 Negligible


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


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)


AQAL (%)


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


mean AQAL (%)



No. of 24hr means

>50µg/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


mean AQAL (%)



No. of 24hr means

>50µg/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


mean AQAL (%)



No. of 24hr means

>50µg/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)


AQAL (%)


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)


AQAL (%)


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



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


N/ha/yr)


range


range



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%


Chudleigh Caves & Woods SSSI Broadleaved deciduous woodland 0.043 0.4% 0.2%



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N/ha/yr)


range


range




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



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%





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.


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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.

Devon County Council 48 422.03019.00029 A382 Corridor Improvements – Air Quality Assessment August 2015

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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

table 5-1 potential dust emission magnitude · 2016-09-15 · construction material, i.e....

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