PUBLIC INQUIRY

IN THE MATTER OF THE HIGHWAYS ACT 1980 AND THE ACQUISITION OF LAND ACT 1981

AND IN THE MATTER OF:

THE M4 MOTORWAY (JUNCTION 23 (EAST OF MAGOR) TO WEST OF JUNCTION 29 (CASTLETON) AND CONNECTING ROADS) AND THE M48 MOTORWAY (JUNCTION 23 (EAST OF MAGOR) CONNECTING ROAD) AND THE LONDON TO FISHGUARD TRUNK ROAD (EAST OF MAGOR TO CASTLETON)) COMPULSORY PURCHASE ORDER 201-

-and-

THE M4 MOTORWAY (JUNCTION 23 (EAST OF MAGOR) TO WEST OF JUNCTION 29 (CASTLETON) AND CONNECTING ROADS) AND THE M48 MOTORWAY (JUNCTION 23 (EAST OF MAGOR) CONNECTING ROAD) SCHEME 201-

-and-

THE M4 MOTORWAY (WEST OF MAGOR TO EAST OF CASTLETON) AND THE A48(M) MOTORWAY (WEST OF CASTLETON TO ST MELLONS) (VARIATION OF VARIOUS SCHEMES) SCHEME 201-

-and-

THE LONDON TO FISHGUARD TRUNK ROAD (EAST OF MAGOR TO CASTLETON) ORDER 201-

-and-

THE M4 MOTORWAY (JUNCTION 23 (EAST OF MAGOR) TO WEST OF JUNCTION 29 (CASTLETON) AND CONNECTING ROADS) AND THE M48 MOTORWAY (JUNCTION 23 (EAST OF MAGOR) CONNECTING ROAD) AND THE LONDON TO FISHGUARD TRUNK ROAD (EAST OF MAGOR TO CASTLETON) (SIDE ROADS) ORDER 201-

(‘THE M4 CORRIDOR AROUND NEWPORT SCHEME’)

PROOF OF EVIDENCE ON WATER QUALITY

OF

Dr Tristan Willmott Hatton-Ellis

FOR THE NATURAL RESOURCES BODY FOR WALES

Contents

  1. Introduction
  2. Background
  3. General
  4. Application of Water Quality Standards to the Gwent Levels
  5. Legal and policy framework
  6. Site context
  7. Issues
  8. Alternatives
  9. Conclusions
  10. References
  1. INTRODUCTION
  2. I am Dr Tristan Willmott Hatton-Ellis. I am the Senior Freshwater Ecologist in the Evidence Analysis Group of the Natural Resources Body for Wales (NRW). I am based at NRW's office in Bangor.
  3. I have a B.A. Honours degree (1st Class) in Zoology from the University of Oxford, and a Ph.D. for research into the population genetics of freshwater bryozoans from the University of Bristol.
  4. As NRW’s Senior Freshwater Ecologist, I lead on the provision of scientific advice on the management, monitoring, evaluation and impact of freshwater ecosystems in Wales. I undertake and commission research and survey projects, provide scientific advice and guidance within NRW and to external partners, and represent NRW at relevant Wales and UK fora. I have 18 years’ experience working on freshwater conservation in Wales.
  5. I have held the above position in NRW since April 2013 following its establishment from the three predecessor bodies. From 1998, I was the Rivers Ecologist in the Natural Science Support Group of the Countryside Council for Wales and in 2003 I became Senior Freshwater Ecologist at CCW. I work with UK conservation and environment agencies to develop national monitoring and management guidance; advise operational staff on the selection, designation and management of statutory sites (national and European) of freshwater interest; comment and contribute to license applications, licensing issues and high profile casework that affects freshwater species.
  6. This proof of evidence has been prepared on the basis of the evidence presented in the Environmental Statement (ES) prepared by the applicant, the supplements to the ES and the relevant proofs of evidence produced by the Welsh Government. As a reasonable public authority, NRW will review its position in the light of any new evidence admitted to the Public Local Inquiry into the M4 Corridor around Newport scheme.

BACKGROUND

1.6.General

1.6.1.This proof of evidence is in relation to the proposed M4 relief road around Newport and its potential effects on the water quality of the Gwent Levels ditch ecosystems.

1.6.2.Road traffic releases various pollutants onto the road surface during normal operation. Runoff from the road surface during rainfall events washes off these pollutants and then enters adjacent water bodies via drains. This has the potential to cause pollution events in receiving water bodies.

1.6.3.Consultants acting for Welsh Government have identified a series of mitigation measures to intercept this pollution and hence reduce its impact. These are, in sequence:

-Grass lined channels;

-Oil filters;

-Settlement lagoons;

-Reedbeds.

1.6.4.These have been assessed using the Highways Agency Water Risk Assessment Tool (HAWRAT), a standard tool for assessing the potential impacts of road pollution on water courses.

1.6.5.The Gwent Levels SSSIs are a unique system and one of the most important and extensive wetlands in the UK. Their conservation importance is explained in detail in the SSSI Proof of Evidence.

1.6.6.A key factor affecting aquatic habitats is water quality. Water pollution has been repeatedly shown to have profound and multiple effects on species, habitats and ecosystems. Pollutants include a wide range of substances including toxins (e.g. pesticides, metals); substances that affect the growth of animals and plants such as plant nutrients (especially nitrogen and phosphorus) or endocrine disruptors; and substances that alter the physico-chemical nature of the ecosystem such as sediment and salts. Some pollutants may have more than one ecological effect.

1.6.7.Pollution can have various different effects on freshwater ecosystems which can be broadly summarised as:

  • Direct effects that harm populations of individual species, for example by causing death or by affecting growth and reproduction;
  • Indirect effects on the ecosystem that (a) favours one species or group of species over another, or (b) creates altered environmental conditions such that some species can no longer survive.
  1. Water quality is dependent both on the loading of pollutants from external sources, and on the water quality and flow of the receiving watercourse. For most pollutants, dilution is important for reducing their ecological impact. In addition, the concentration of dissolved solutes such as calcium may affect the toxicity of some pollutants, especially dissolved metals.
  2. Pollution is generally regulated through the use of standards. Standards are usually values that may not be exceeded or more rarely, a minimum value (e.g. dissolved oxygen). Values may be expressed either as an annual average, or as a maximum/minimum allowable concentration. Some standards also include more than one statistic, and may also include methods to allow for natural environmental variation insofar as it affects the implementation of the standard.
  3. These are set based on reviews of available scientific evidence, usually based on laboratory experiments to determine toxicity to various organisms. Although these laboratory tests include a range of effects, more studies tend to examine mortality than sublethal effects such as growth and reproduction. Indirect effects on ecosystems are more difficult to study experimentally and hence may not be reflected in standards. A common approach to counter this uncertainty is to set the standard at some fraction of the known effect level, such as 1/10 of the lethal dose.
  1. Application of Water Quality Standards to the Gwent Levels
  2. Although there are a wide range of studies on the effects of different pollutants on freshwaters, relatively few of these have been carried out on ditch systems. This has limited NRW’s ability to provide specific advice that relates to impacts on ditches. I know of no information regarding the impact of pollutants on the SSSI feature species.
  3. Although rules for monitoring water bodies do not require NRW to routinely monitor and classify all of the Gwent Levels ditches, the Water Framework Directive nevertheless requires these water bodies to meet WFD standards where applicable.
  4. Ditch monitoring guidance designed by the Conservation Agencies (JNCC, 2005) recommends the use of now obsolete chemical monitoring methods designed by the Environment Agency for rivers. The ditch monitoring guidance is currently under review and will be updated to reflect current WFD standards.
  5. The Countryside Council for Wales previously identified a series of trigger levels designed to apply to the Gwent Levels. These are not environmental standards in the formal sense but were intended as alarm values to identify one-off pollution events. The way in which they were derived has not been documented in detail, however.
  6. For this reason, NRW has mainly used Water Framework Directive standards as the basis for assessing impacts on water quality. Although these are not necessarily optimised for ditch environments, they are technically robust and defined in Law via the Water Framework Directive (Standards and Classification) Directions (England and Wales) 2015.
  7. The standards used are predominantly those for rivers as these are considered to be the most ecologically relevant. WFD standards include allowance for natural reference conditions where relevant, so the extremely low flows in the Levels is not necessarily an obstacle in itself.
  8. However, NRW is mindful that in some cases the WFD standards may not be achievable in a ditch environment. For this reason I carried out a specific sense check using the water quality data supplied to us by Welsh Government, in order to establish whether the standards were achievable in the Levels.
  9. This exercise established that one standard, for dissolved oxygen in rivers, could not be applied in the Gwent Levels. This is not surprising as the lack of flow and high biomass of aquatic plants naturally leads to intermittent oxygen sags in small water bodies such as ponds and ditches.
  10. All other WFD standards were compliant in all or some sampling locations. Failures could reasonably be related to existing environmental pressures.
  11. A potential risk pathway is the effect of saline runoff resulting from gritting operations in winter. General information on the salt sensitivity of British plant species has been published by Hill et al. (1999). This is summarised in Appendix B and shows the Gwent Levels aquatic plant flora to be generally composed of salt-intolerant species.
  12. The best way to monitor this is by measuring chloride concentrations, but no WFD standard exists for either lakes or rivers. Initially I proposed using the WFD conductivity standard for lakes, but in discussions with Welsh Government and their consultants it was agreed to use a chloride standard. As a result, NRW proposed a simplified version of the standard used by British Columbia (Canada) with a maximum allowable concentration of 300 mg l-1. This value falls within the lower end of the range of values reported by Findlay & Kelly (2011) and was agreed with WG in December 2016.

1.7.12.The final list of standards that NRW considers applies to the Gwent Levels is set out in Appendix A. Of particular concern in the context of the M4 scheme are those for suspended solids, metals, polycyclic aromatic hydrocarbons (PAHs), and chloride as these are likely to reach problematic concentrations in road runoff.

1.7.13.Metals are highly toxic to living organisms and naturally occur at very low concentrations. In general, soluble forms of metals are much more toxic to life, but most metals are comparatively insoluble. Metals are mainly transported bound to sediment, but under certain chemical conditions they may be released into the environment. As chemical elements, metals cannot be degraded into less harmful components, but their availability can be reduced by binding to other substances such as clays and / or being physically buried.

1.8.Legislation, policy and guidance background

1.8.1.The legislation and policy background in relation to the Gwent Levels SSSI are set out in detail in the SSSI proof of evidence and are not reiterated here.

1.8.2.Water Quality standards for the Water Framework Directive are set out in the Water Framework Directive (Standards and Classification) Directions (England and Wales) 2015.

1.8.3.Section 3 of the Well-being of Future Generations (Wales) Act 2015 (‘the 2015 Act’) creates a ‘well-being duty’ by which public bodies, including the Welsh Ministers, ‘… must carry out sustainable development’.[1] The 2015 Act provides this must include setting and publishing “well-being objectives” designed to maximise its contribution to achieving each of the well-being goals and ‘taking all reasonable steps (in exercising its functions) to meet those objectives’.[2]

1.8.4.In the 2015 Act, “sustainable development” means ‘the process of improving the economic, social, environmental and cultural well-being of Wales by taking action, in accordance with the sustainable development principle […] aimed at achieving the well-being goals’.[3]

1.8.5.Section 4 of the 2015 Act sets out “well-being goals” amongst which is ‘A resilient Wales’, which is defined in the 2015 Act as:

‘A nation which maintains and enhances a biodiverse natural environment with healthy functioning ecosystems that support social, economic and ecological resilience and the capacity to adapt to change (for example climate change).’

1.8.6.Further, section 6 of the Environment (Wales) Act 2016 (‘the 2016 Act’), places a ‘biodiversity and resilience of ecosystems duty’ on public authorities exercising functions in Wales. Under section 6 of the 2016 Act, a public authority ‘must seek to maintain and enhance biodiversity in the exercise of functions in relation to Wales, and in so doing promote the resilience of ecosystems, so far as consistent with the proper exercise of those functions’.

1.8.7.In the 2016 Act, “biodiversity” is defined as ‘…the diversity of living organisms, whether at the genetic, species or ecosystem level’.[4] The 2016 Act specifies certain matters relating to the “resilience of ecosystems” which public authorities must take into account in complying with its duty under section 6:

‘… a public authority must take account of the resilience of ecosystems, in particular the following aspects—

(a) diversity between and within ecosystems;

(b) the connections between and within ecosystems;

(c) the scale of ecosystems;

(d) the condition of ecosystems (including their structure and functioning);

(e) the adaptability of ecosystems.’

1.8.8.In the exercise of their functions, the Welsh Ministers have a further, separate duty, under section 7 of the 2016 Act, to ‘take all reasonable steps to maintain and enhance the living organisms and types of habitat included in any list published under this section’.

1.8.9.Several SSSI feature species occurring in the Gwent Levels, as well as the ditch ecosystem in general, are sensitive to water quality including Great Crested Newt (for which see separate proof of Jessica Poole on Ecology and Gwent Levels SSSIs [NRW ).

1.8.10.Thus, Welsh Government has a duty to ensure this development does not pose adverse water quality impacts on the ditch features.

  1. SITE CONTEXT
  2. Relative to current WFD standards, water quality in the Gwent Levels is generally moderate to poor. The principal issue is nutrient concentrations, which are generally too high. This is likely to be a consequence of agricultural runoff and outflows from septic tanks. However, concentrations of pollutants likely to be discharged from road runoff are currently low to very low in the Gwent Levels ditches and consequently pass their environmental standards.
  3. The lack of dilution in summer is particularly important when assessing water quality impacts for the Levels. Rainfall patterns for Cardiff (the nearest Met Office weather station) show the wettest months to be October-January and the driest to be April-June (Figure 1). Climate predictions from UKCIP under a medium emissions scenario suggest that summer rainfall will reduce by about 20% in the area by the 2050s (Source: ukclimateprojections.metoffice.gov.uk)
  4. This means that any pollutants from the road not been flushed out of the system by this time will likely remain there until the following autumn (i.e. the whole growing season) during a normal or a dry year, with enhanced potential to cause ecological damage.

Figure 1. Monthly average rainfall for Cardiff Bute Park (Lat 51.488, Long -3.187), 1981-2010. Source: The Met Office,

2.4.According to Appendix 16.3 (sect 2.1.18, p.5), the grass lined channels are designed to cater for a 1 in 100 year storm event with a 30% allowance for climate change. The lagoons and culverts are also stated to incorporate an allowance for climate change, though it is not stated what this is. UKCIP09 models suggest that a 30% increase in rainfall is an appropriate threshold for this part of Wales.

2.5.The subsequent HAWRAT assessment uses a rainfall statistic of 850 mm annual rainfall which is stated to be the annual rainfall for Newport. However, this is not cited and the two nearest weather stations to Newport (Cardiff and Usk weather stations) both have annual rainfall in excess of 1000 mm (Cardiff: 1152 mm; Usk: 1076 mm). Therefore the HAWRAT modelled value represents the current situation with no allowance for climate change.

2.6.In discussion with Richard Graham, we established that a higher rainfall would result in the HAWRAT model providing a lower concentration and hence a lower estimate of impact.

2.7.However, higher rainfall would also result in more rapid and efficient transport from the road, potentially meaning that mitigation measures have insufficient capacity and hence that water treatment is less effective than predicted.

  1. ISSUES
  2. The HAWRAT tool models the likelihood of acute pollution events occurring, but is not intended to measure the scope for and impact of long-term pollutant accumulation. This risk needs to be addressed in the assessment, especially with regard to chloride and metals, both of which have the potential to accumulate in the environment.
  3. I understand that the traffic modelling has recently had to be updated. This has potential ramifications for the water quality environmental statement as increased traffic load would have consequences for pollutant loading and hence for the effectiveness of the mitigation measures.
  4. Lack of summer dilution is considered a particular risk following a dry spring punctuated by an occasional heavy rainfall event that washes pollutants from the road. Unfortunately the data Welsh Government has supplied us is only collected at quarterly intervals so it is not possible to assess this in detail.
  5. NRW is content that Welsh Government has followed best practice guidance in terms of collecting pre-project water quality monitoring data, and in terms of using an established assessment tool (the Highways Agency Water Risk Assessment Tool, HAWRAT). However, the HAWRAT manual advises that “The tool is also limited in its ability to assess the impact on streams where the flow is intermittent or seasonal.”. This does not necessarily invalidate the HAWRAT outputs, but it does reduce confidence in them.
  6. The evidence provided by Welsh Government is poorly presented and this means that I was not always able to clearly understand the basis for their conclusions.