This document discusses air quality impacts on the Ashdown Forest SAC from the Wealden District Council local plan. It summarizes the council's HRA which found adverse impacts from increased traffic emissions. Natural England guidance is examined which advises on screening thresholds and modeling. The council proposes developer contributions to fund monitoring and research rather than direct mitigation measures. Effectiveness and certainty of mitigation delivery would need to be demonstrated for the local plan to proceed lawfully.

1. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
WEALDEN DISTRICT COUNCIL
LOCAL PLAN HRA
Dr Claire Holman
Brook Cottage Consultants

2. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Contents
1. Wealden Council and Ashdown Forest
2. Habitats Regulation Assessment (HRA) on emerging local plan 2018-2028
3. Natural England’s June 2018 Guidance
4. Mitigation in the Wealden Local Plan 2018-2028
5. Summary and Conclusions
2

3. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
How Should the Air Quality Impacts be Assessed?
• Can air quality impacts be screened out using the DMRB screening
criterion of 1,000 AADT?
• Given the unreliability of past nitrogen oxides (NOx) emissions
forecasts for road transport can we rely on a reduction in emission in an
HRA?
• What about ammonia emissions from road traffic?
• Note this addresses air quality impacts not the effects of these impacts
on habitats.

4. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Wealden District Council’s Protection of Ashdown Forest
4
• SSSI/SPA/SAC
• SAC
• Northern Atlantic wet
heaths with Erica tetralix
• European dry heaths
• One of the largest
continuous blocks of
lowland heath in SE
England
• covers 2,729 ha

5. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Why is Wealden Important – Legal Challenges
• Steel Cross (103 houses in Crowborough)
• Refused consent (2014)
• Inspector gave consent (2015)
• High Court quashed consent (appropriate assessment) (2016)
• Developer appeal refused (2017)
• Lewis and South Downs Joint Plan
• WDC Challenged HRA (2016)
• Court stated Natural England’s advice (based on Highway’s
England’s DMRB) “was plainly incorrect”
• Natural England must reconsider its advice in the light of this
judgment.
• The 1000 AADT cannot be used to screen out the need for
assessment of a project or plan alone.
• Highways England should re-examine and clarify use of DMRB
1000 AADT screening criteria

6. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
WealdenActions 2017
• March 2017
• Wider impact than just relating to the A26 as
initially considered as part of the adopted Core
Strategy - A22, A275, B2026 and B2110
also affected
• June 2017
• …we are not in a position to determine some
live planning applications within the District
which have potential to adversely affect the
SAC as a result of Air Quality impacts …period
of determination be extended until Friday 29th
September 2017,
• September 2017
• asked for confirmation that the period of
determination be further extended until Friday
19th January 2018

7. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
WealdenActions 2017-18
• Objected to planning applications in neighbouring
authorities as far away as Eastbourne (25km from the
SAC)
• Objected to the Mid Sussex draft local plan –
subsequently withdrawn.
• Submission local plan (2013-2028) published for
consultation August 2018 (includes the Steel Cross
site)
• Interim Mitigation Strategy Tariff Guidance for
residential dwelling published September 2018
(£3,100/dwelling) to raise £20m over period 2018-
2040

8. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Wealden’s Research Programme

9. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
August 2018: HRAConclusions
• Unlikely Ashdown Forest SAC to be restored to
favourable conservation status should growth as that
proposed take place.
• Should additional concentrations and deposition be
added as a result of the Wealden Local Plan and growth
elsewhere then this will result in a worsening of the
current situation which already exceeds environmental
limits.
• Wealden Local Plan both alone and in combination will
result in an adverse impact on the integrity of the site
and will create conditions that would inhibit restoration of
the annex I habitats should this growth take place
unchecked.
Note: Air quality modelling used a bespoke methodology

10. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
AQAScenarios
Traffic
• 2015 Existing traffic
• 2028 No growth (existing traffic)
• 2028 No WEDC growth (Existing traffic + amended
TEMPRO growth to 2028 but excluding WLP)
• 2028 with plan (Existing traffic + amended TEMPRO
growth to 2028 +WLP
NOx emissions per vehicle
• 2015 (for which the model has been verified against local
measurements)
• Emissions per vehicle fall - CURED 3A model
• Emissions per vehicle fall - Defra’s EFT V8.0.1
NH3 emission per vehicle
• Emissions per vehicle in 2015
Impact of WLP determined by
comparing 2028 scenarios
assuming no improvement from
2015 emissions per vehicle
Two different methodologies
used with the ‘big leaf model’ to
calculate deposition fluxes.
Deposition velocities not used

11. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
AQ Conclusions
• WLP In isolation - potential adverse impact when
considering increases in concentrations and deposition
against critical levels and critical loads.
• WLP In-combination SAC continues to exceed the critical
load for nitrogen deposition; increases deposition fluxes
and exacerbates the exceedance through higher
concentrations as well as an increased area of the SAC
predicted to be above the critical load.
• The WLP results in additional concentrations for all
pollutants and deposition fluxes across the SAC, the areas
predicted to experience the highest deposition increases
are those by the side of the roads.
This ignores
• any benefit of emission
reductions that are likely to
take place between 2015 and
2028
• Government plans to reduce
NOx emissions (2016 NECD
and 2017 Air Quality Plan)
• Traffic forecasting
uncertainties were not
considered

12. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Natural England’s Opinion
• The competent authority should assess the implications of a plan
or project against an improving background trend.
• Scenario A is wholly unreasonable
• The improvements coming forward close to roads is declining
faster than the additional inputs as part of the 10 year Local Plan.

13. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Ammonia Emissions from Vehicles
• First WDC air quality report suggested that NH3e emission will
include in the future
• NH3 used in diesel vehicle NOx abatement systems
• Traditionally though to come from petrol vehicles with three way
catalysts - this source is declining
• Uncertainty regarding where the use of NH3 (from Adblue) will
increase exhaust emissions
• Heavy duty - NH3 emission limit, but not for light duty (yet!)
• Is it important when agriculture is the main sources of NH3?

14. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Natural England’s June 2018 Internal Guidance
Guidance made public to
explain NE’s approach to
assessing the effects of
road traffic
emissions on European
Sites particularly in light
of the Wealden Judgment
2017.

15. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Natural England’sAdvice on Screening
• Step 1: Does the proposal give rise to
emissions which are likely to reach a
European site?
• Step 2: Are the qualifying features of sites
within 200m of a road sensitive to air
pollution?
• Step 3: Could the sensitive qualifying
features of the site be exposed to
emissions?
• Step 4: Application of screening thresholds
(alone and in-combination)
Care should be taken to avoid unnecessarily
combining the insignificant effects of the plan
or project with the effects of other plans or
projects which can be considered significant
in their own right. i.e. ‘don’t combine individual
biscuits (=insignificant) with full packs
(=significant)
Note: Mitigation cannot be taken into account
during screening

16. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Natural England’sAdvice on Screening
• Step 1: Does the proposal give rise to
emissions which are likely to reach a
European site?
• Step 2: Are the qualifying features of sites
within 200m of a road sensitive to air
pollution?
• Step 3: Could the sensitive qualifying
features of the site be exposed to
emissions?
• Step 4: Application of screening thresholds
(alone and in-combination)
Industrial/agricultural/road sources of air
pollution need considering – different distance
criteria

17. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Distance Criteria
• Traffic (DMRB)
• 200 m from centre of the road (DMRB)
• Point Sources (Environment Agency)
• Generally 10 km
• Some exceptions
These distance criteria should not be applied
in all cases. Professional judgement may be
needed.
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
0 10 20 30 40 50 60 70 80 90 100
NOx(µg/m3)
Distance from edge of road (m)

18. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Screening Thresholds
• DMRB
• 1,000 AADT – all traffic
• 200 AADT Heavy duty vehicles
• Environmental Permitting
• 1% of critical level/load
Explanations
• AADT = annual average daily traffic
• DMRB = Design manual for roads and
bridges
• Environment Agency/NRW use 1% of
critical level/load for environmental
permit applications (except intensive
agriculture)
• Changes more than 1% simply
identifies that further investigation is
required as part of the risk assessment
• Changes more than 1% do not mean
there is a significant .

19. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Natural England’s Opinion
• 1% of the critical level/load and DMRB
AADT thresholds - roughly equivalent
• Below this level emissions are widely
considered to be imperceptible and, in the
case of AADT, undetectable through the
DMRB model.
• Where AADT threshold exceeded but 1%
threshold not exceeded the 1% threshold
would override the 1000 AADT guideline
• The can be a high degree of confidence in
these thresholds to screen for risks of an
effect.
• Thresholds have to be used alone and in-
combination with other projects and plans
BUT
• AADT and 1% thresholds not equivalent as
based on old data - emissions have
changed but the critical loads/levels have
not
• If AADT threshold exceeded the impact of
traffic emissions would be modelled
• Note: experienced air quality professionals
would not use the publicly available DMRB
spreadsheet model - out of date

20. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Normal Practice
• If AADT is exceeded (alone or in
combination) air quality dispersion
modelling would be used.
• Modelling would for a worst case location
where there is relevant habitat/species,
• Or on a grid to provide pollution contours
(isopleths). This can be overlaid onto a plan
of the habitats to identify where the 1%
threshold is exceeded and there are
relevant habitats/species.
Good practice
• AQ and Ecology specialists should work
together at all stages of the assessment to
gain from both areas of expertise.

21. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
WDC’s Proposed Mitigation
Financial contribution for a package of measures including:
a) Air quality and ecology monitoring of Special Area of Conservation;
b) Investigation of and where suitable the potential implementation of measures to
contribute to a wider SNAP, where this is considered appropriate. This could
include measures to strengthen nitrogen sensitive habitats;
c) Investigation of measures to reduce local transport emissions from vehicles;
d) Reduction of emissions from other land uses that affect the Special Area of
Conservation;
e) Provision of electric charging points for electric vehicles within public areas;
f) Resources relevant to promotional/ instructive material regarding public and
sustainable transport use and walking; and
g) Provision of electric public transport, cycling and walking facilities and scheme to
reduce the use of petrol and diesel vehicles.

22. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
WDC’s Proposed Mitigation
h) Provide appropriate electric vehicle charging infrastructure.
i) Demonstrate that freight traffic resulting from new development will seek not o impact the
Special Area of Conservation through routing arrangements and travel plans;
j) Provide personalised travel planning; and
k) All new housing and employment development to have the ability to connect to high speed
broadband.

23. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Proposed Mitigation fund

24. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Natural England
• It is a matter for WDC, the as competent authority, to
reach its conclusion on the Appropriate Assessment,
having considered the advice provided by Natural
England.
• If WDC decides to depart from NE advice and considers
that mitigation is required, it will be necessary for the
council to demonstrate that the mitigation will be
effective and there is sufficient certainty as to its
delivery.

25. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Summary and Conclusions
1. WDC’s litigation resulted in:
• Clarity regarding the use of the 1000AADT threshold
• New guidance from Natural England
2. The WDC HRA assumes no improvement in emissions i.e. does not take into account
other relevant plans
3. WDC’s HRA used to justify developer contributions to a large (£20m) fund that will be
largely used to fund the research (monitoring) project, communication programme and staff
time – not mitigation measures (contingency is >25%);
4. Mitigation must be shown to be effective and deliverable otherwise unlawful and subject to
legal challenge.