PUBLIC INQUIRY DOCUMENTbailey.persona-pi.com/Public-Inquiries/M4-Newport/E - PI...PUBLIC INQUIRY DOCUMENT REFERENCE NO. : ID/054 revised RAISED BY: Matthew Jones DATE: 19/05/17

M4 Corridor around Newport

PUBLIC INQUIRY DOCUMENT

REFERENCE NO. : ID/054 revised

RAISED BY: Matthew Jones DATE: 19/05/17

RESPONDED BY: ‐ DATE:

SUBJECT: Surface Water Monitoring Protocol

Please attached the Surface Water Monitoring Protocol.

This document has been revised as follows Para. 3.1.8 line 4 ‘removal’ added after ‘sediment’

This ID has been sent to NRW.

Welsh Government

M4 Corridor around Newport Surface Water Monitoring Protocol

05 May 2017

CVJV/AAR 3rd Floor Longross Court, 47 Newport Road, Cardiff CF24 0AD

Welsh Government M4 Corridor around Newport Surface Water Monitoring Protocol

Contents

1 Introduction 1

1.2 Objectives 2 1.3 Monitoring Network 2

2 Monitoring 7

2.1 Surface Water Sampling 7 2.2 Quality Assurance and Quality Control 8 2.3 Reen Sediment Sampling 9 2.4 Biological Monitoring 10 2.5 Control and Trigger Levels 11 2.6 Winter Treatment Runoff 14 2.7 Monitoring Frequencies 15

3 Maintenance of Water Treatment Areas 16

4 Data Management and Reporting 18 Drawings JER6591_FigureWP1 – FigureWP12: Water Treatment Areas and proposed monitoring Appendices Appendix 1 CCW Guidance Note 4: Water Quality Monitoring on the Gwent Levels SSSI Appendix 2 NRW Trigger Levels for the Gwent Levels SSSIs Appendix 3 Water Quality Statistics for Current Baseline Monitoring Dataset Appendix 4 File Note: Grass Lined Channels Maintenance


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1 Introduction 1.1.1 The Welsh Government proposes to build the M4 Corridor around Newport

(M4CaN) to address traffic related problems around Newport. This comprises a new three lane motorway to the south of Newport and associated Complementary Measures (the ‘Scheme’).

1.1.2 It is proposed to capture, treat and discharge operational run-off from the new section of motorway to the local reen network via roadside grass lined channels linked to 12No. Water Treatment Areas (WTA). The new section of motorway and location of associated Water Treatment Areas (WTAs) is shown in Drawings JER6591_FigureWP1 – FigureWP12.

1.1.3 An assessment of the potential for impact on surface water quality arising from the proposed discharges was undertaken as part of the Environmental Impact Assessment for the proposed Scheme and presented in Chapter 16 of the March 2016 Environmental Statement.

1.1.4 This assessment concluded that concentrations within reens of pollutants of concern from operational traffic were unlikely to exceed NRW imposed Trigger Levels for the Gwent Levels SSSIs. Furthermore, the assessment concluded that existing baseline water quality of reens was unlikely to be adversely impacted, i.e. causing existing concentrations of the pollutants of concern to rise.

1.1.5 NRW in response to the Environmental Statement expressed the view that there was sufficient uncertainty in the assessments for some effects on water quality to occur.

1.1.6 The Environment Statement also proposed a number of contingency measures to reduce the risk of unacceptable operational water quality effects, i.e. breaches of NRW Trigger Levels, from materialising. A principal contingency measure was to undertake verification monitoring of the reen network to establish an appropriate evidence base to allow the timely and confident identification of any potential effects on reen water quality.

1.1.7 In addition to water quality it was also recognised that biological indicators would provide the most direct means of identifying adverse effects to the SSSIs. For this reason invertebrate taxa monitoring is also identified as an important evidence base for capture during verification monitoring.

1.1.8 The surface water monitoring protocol detailed below is therefore designed to provide a long term evidence base for the following:

• Surface water quality of the reens within the Gwent Levels, upstream and downstream of the proposed WTA discharges;

• Sediment quality upstream and downstream of the proposed WTA discharges;


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• Invertebrate taxa at the same location as the aforementioned surface water quality monitoring points to establish WHPT and PSI indices.

1.2 Objectives 1.2.1 The objective of this protocol is to define the scope of performance monitoring of

WTAs associated with the operation of the Scheme. This will form the basis of agreement between Welsh Government and NRW to satisfactorily address regulatory concern regarding water quality and therefore ecological effects within the Gwent Levels SSSIs.

1.2.2 WTA discharge point locations as defined within the Drainage Strategy (Appendix 2.2 to the March 2016 ES) are shown in Table 1.1 together with proposed upstream and downstream assessment locations and as shown on the drawings. Further to this, a frequency of monitoring (both initial and long term) is suggested in addition to an appropriate monitoring suite.

1.2.3 Statistical methods of defining management control levels for the sensitive reen network at downstream locations of the WTA are also defined.

1.2.4 Finally, options for a response to NRW concerns regarding winter treatment (rock salt) impacted runoff are provided with an additional associated monitoring strategy.

1.3 Monitoring Network 1.3.1 On instruction from Welsh Government, surface water monitoring has been

undertaken on a quarterly basis since May 2015 with the primary remit of baselining the reens that are proposed to receive discharges from the Water Treatment Areas. Further details regarding this monitoring are included within Appendix 16.2 of the Environmental Statement (March 2016).

1.3.2 In proposing water quality monitoring points for the aftercare period of the scheme, downstream locations have been selected to best represent the quality of the reen following discharge from the WTA. However, in some instances, this has been governed by land access and in such cases monitoring locations have been selected based on a current understanding of access to the reen. It is acknowledged that this may undergo revision prior to the commencement of the aftercare monitoring. This issue specifically relates to the following locations:

• WTA 1 – discharges to Pwll Bargoed Reen outside of the SSSI boundary. Proposed monitoring point is approximately 360 m downstream of the WTA outfall at the current baseline monitoring point, which is collected from the public foot path crossing of the reen.

• WTA 2 – discharges to Tyn y Bryn Reen. Proposed monitoring point is approximately 500m downstream of the outfall and also downstream of a confluence with a tributary of the reen. Pending land access


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arrangements, this will ideally be moved upstream of the confluence and closer to the WTA discharge point.

• WTA 5 – discharging to Morfa Grown Reen. Land access issues during the present monitoring period have hindered collection of monitoring data from Morfa Gronw Reen. Pending agreement, the use of the proposed NRW access tracks for the WTAs would be requested in order to obtain a representative sample closer to the WTA discharge point. The current proposal (based upon collecting a sample from a road crossing of the reen) is approximately 730m downstream of the WTA outfall.

1.3.3 The proposed monitoring network as set out in Table 1.1 is designed to allow the potential impact of the proposed Scheme drainage on baseline reen water, bed sediment and ecological quality to be quantified.

1.3.4 By making these measurements both up and downstream of each of the 15 No. proposed discharges, together with the discharge itself prior to mixing within a reen, any measurable effect of the discharge can be determined.

1.3.5 Downstream locations have been selected based upon the proposed discharge point of the WTA. Where possible, the monitoring location has been selected as near as possible to the discharge point and within the same reen.

1.3.6 For reen sediment quality, it is proposed collect a sample from the discharge point of the WTA to establish whether sedimentation is occurring and whether any of the pollutants of concern are measurably accumulating.

1.3.7 Invertebrate monitoring will be undertaken both up and downstream of each proposed discharge at the same locations as surface water quality monitoring to establish indices with which to evaluate potential adverse population effects beyond expected naturally variability at each location as observed at the upstream sample.

1.3.8 Additionally, 4 ambient sampling locations are to be located away from potential influence of the Scheme for capturing background biology indices. The precise locations of these monitoring points will be agreed with NRW but will be representative of morphology and biological potential of the reens proposed to receive WTA discharges.

1.3.9 The selected monitoring locations for the WTA can be seen on JER6591_FigureWP1 – FigureWP12 and are detailed in Table 1.1.


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Table 1.1: Monitoring protocol sampling locations defined by WTA

WTA Monitoring Point NGR Reen Name Justification Water

Quality Sediment Quality

Invertebrate Indices

WTA 1

Upstream 325537 183682 Stream north of Pwll Bargoed Reen

Monitoring point is c.90 upstream of discharge point. x x

Discharge 325601 183615 x x

Downstream 325895 183669 Monitoring point is c.330m downstream of discharge point x x x

WTA 2

Upstream 326885 183984

Tyn-y-brywyn Reen

Monitoring point is c.70m upstream of discharge point. x x


Downstream 326760 183544 Monitoring point is c.400m downstream of discharge point. x x x

WTA 4a

Upstream 328552 183571 Percoed Reen Monitoring point is c.240m upstream of discharge point x x

Discharge 328537 183397 Replacement Reen x x

Downstream 328382 183466 Replacement Reen Monitoring point is c.220m downstream of discharge point. x x x

WTA 4b

Upstream 328552 183571 Percoed Branch West Reen Monitoring point is c. 90m upstream of discharge point x x

Discharge 328497 183530 Replacement Reen

x x

Downstream 328382 183466 Monitoring point is c. 160m downstream of discharge point. x x x

WTA 5

Upstream 329510 183769

Morfa Gronw Reen




WTA 6

Upstream 334320 185453

Lakes Reen

Upstream monitoring point is c.70m upstream of discharge point. x x


Downstream 334455 185203 Downstream monitoring point is c.230m from discharge point. x x x

WTA 7

Upstream 335055 185690

Julians Reen





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Table 1.1: Monitoring protocol sampling locations defined by WTA (Continued)

WTA Monitoring Point NGR Reen Name Justification Water

Quality Sediment Quality


WTA 8

Upstream

Ellen Reen

x x


Downstream 336452 185516 Downstream monitoring is c.200m downstream of discharge point,

prior to junction of Blackwall Reen which may carry discharge of WTA 8a

x x x

WTA 8a

Upstream

Blackwall Reen

x x



WTA 9

Upstream 339876 186161 100 Perches Reen Monitoring point is c.240m upstream of discharge point on reen. 100

Perches Reen is culverted beneath Queens Way to Middle Road Reen Diversion.

x x

Discharge 339844 186006 Middle Road Reen

Diversion

x x


WTA 10

Upstream 341378 186295 Rush Wall Reen North



Downstream 341007 186240 Replacement Reen Downstream monitoring is c. 200m from discharge point. x x x

WTA 11b

Upstream

Mill Reen

Private land – Mill Reen access needs to be arranged. x x


Downstream 342490 187877

Downstream monitoring is no further than 50m downstream of discharge point.

x x x

WTA 11c

Upstream Private land – Mill Reen access needs to be arranged. x x


Downstream 342505 187506 Monitoring point is downstream of WTA 11c discharge, but prior to

discharge of WTA 11b which is located south of the current M4 x x x


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Table 1.1: Monitoring protocol sampling locations defined by WTA (Continued) WTA Monitoring

Point NGR Reen Name Justification Water Quality

Sediment Quality


WTA 12a

Upstream No wet channel upstream of proposed discharge x x


Downstream 344111 187051 Pratt Reen North Downstream point is c.250m resulting outfall from the culvert to Pratt Reen North. (TBC) x x x

WTA 12b

Upstream Vurlong Reen

Vurlong Reen currently highly ephemeral. Sampling points will require confirmation under operational status where more persistent flows will

be present.

x x


Downstream x x x


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2 Monitoring

2.1 Surface Water Sampling 2.1.1 For the first 5 years of operation, surface water quality monitoring is proposed on

a monthly basis at both upstream and downstream locations of each WTA discharge point. This frequency is appropriate to allow for the collection of a robust data set to determine baseline variability (measured at the upstream sample) and to obtain statistical descriptors.

2.1.2 Where possible, a nominal distance of approximately 50m has been applied to both upstream and downstream locations. This distance is to allow for mixing of the discharge downstream and provide a representative sample to assess any changes in resulting water quality. Shorter distances may be considered due to locations of potentially polluting local land use or pre-existing discharges or to avoid downstream connections from reens and ditches that would reduce certainty of potential effects on water quality from the WTA alone.

2.1.3 In addition to the collection of water quality samples, the following records will be recorded at each monitoring location on every sampling occasion:

• Visual / olfactory evidence of contamination or general water conditions;

• General water quality parameters collected via multi-parameter probe, e.g. pH, Eh, EC and temperature.

• Secchi depth where possible;

• Water levels within the local surface water system via use of an insitu level logger;

• A visual assessment of flow conditions of the reen;

• A photographic record of each monitoring location.

2.1.4 Collected water samples will be analysed for the following analytes:

• Chloride

• Dissolved Copper

• Dissolved Zinc

• Total Cadmium

• Total Suspended Solids (TSS)

• Calcium

• pH

• Electrical Conductivity (EC)


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• Dissolved Organic Carbon (DOC)

• Speciated PAH

• Speciated TPH

2.1.5 The surface water sampling methodology is in line with the requirements of guidance provided by former-CCW (see Appendix 1) and where appropriate shall reflect historical sampling methodologies.

2.1.6 The sampling methodology shall comprise collecting “grab” water samples from the centre of a reen using a clean, extendable sampling pole. A clean sample container, supplied by the laboratory will be used for each monitoring location to remove the potential for sample cross contamination. The following bottles will be required:

• Plastic – 1 litre

• Glass – 1 litre

• Dissolved Oxygen with associated preservatives

• BOD plastic – 500ml

• Acid Preservatives x 4 (NaOH/HCl/H2SO4/HNO3) – 250ml

• VOC Glass Vials x 2 – 40ml

2.1.7 In the event the sampling container comes into contact with the bank or vegetation the sample shall be discarded. Water quality sampling will be carried out prior to any biological sampling undertaken. This is to ensure the collection of a representative water quality sample, which has not been impacted by sediments mobilised as a result of kick sampling.

2.2 Quality Assurance and Quality Control 2.2.1 Confidence in reported data is essential to management of the WTA performance

and effects on reen water quality. Therefore the following samples shall also be taken during the monthly monitoring round for QA / QC purposes:

• Duplicate / split sample at each location – A single duplicate/split sample shall be taken using the procedures outlined above. These will not be scheduled unless the primary sample indicates a deviation from the typical baseline for each analyte thus providing rapid verification of potential laboratory error. It is recommended that 10% of the samples are duplicated for analysis at the same time to trap laboratory error or sampling bias.

• Field Blank – A single blank, made on-site using deionised water, shall be put in each cool box dispatched to the laboratory. The field blank shall be


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given a unique reference code to allow both laboratory instrument and field cross contamination to be identified; and

• Trip blank – A single trip blank shall be provided by the laboratory for each monitoring round to allow laboratory instrument calibration to be verified.

2.2.2 Water grab samples are transferred to suitable, clean sample bottles (as recommended by the laboratory) and stored in temperature controlled containers. All samples shall be transported to the laboratory for testing on the day of sampling.

2.3 Reen Sediment Sampling 2.3.1 Reen sediment chemical monitoring is proposed on an annual basis at both the

discharge point of the WTA, and the downstream locations, as identified within Table 1.1 and JER6591_FigureWP1 – Figure WP12. This is to determine any accumulations of motorway derived sediment and associated bound pollutants.

2.3.2 The sediment sampling analysis will target the principal heavy metals and hydrocarbons associated with motorway runoff, known to adsorb to sediments as follows:

• Copper

• Zinc

• Cadmium

• Speciated PAH

• Speciated TPH

2.3.3 The sediment sample should be collected from the base of the watercourse at the monitoring point. It is also recommended that during sediment sampling, surface water quality field parameters are also recorded, i.e. pH and eH to allow redox conditions to be assessed.

2.3.4 The results of annual sediment monitoring will be used to determine whether any adverse trends are developing with respect to the above chemical determinands. Assessment of sediment quality is discussed further in Section 2.5.

2.3.5 Where possible, an appraisal will be made at the time of sampling on whether reens show an indication of increasing sediment accumulation, i.e. reducing channel depths, evidence of smothering of vegetation or obvious changes in colouration of reen sediments.


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2.4 Biological Monitoring 2.4.1 The monitoring points identified in Table 1.1 are proposed on an annual basis

during a dry period of summer, between the months of June and July where possible. The locations for monitoring are upstream and downstream locations of the WTA discharge point as seen on JER6591_FigureWP1 – FigureWP12.

2.4.2 Four ambient monitoring sites, co- located with the surface water ambient monitoring points will be included.

2.4.3 A baseline round of sampling in both WTA discharge monitoring points and ambient monitoring sites is proposed for invertebrate monitoring prior to operation of the Scheme. These would be performed in the summer in line with annual monitoring to capture emergent adults and provide comparable data.

2.4.4 Biological sampling will involve the collection of invertebrate sweep netting samples, this being the accepted industry standard (WFD-UKTAG, 2014). Sampling will be carried out within areas of substrate types in proportion with their comparative occurrence. This will allow effective comparison between survey results.

2.4.5 It is also proposed to deploy beetle traps during the annual monitoring rounds in addition to sweep net sampling.

2.4.6 During biological sampling, observations will be made of physical characteristics at each monitoring point to inform interpretation of biological data. This will include photographs taken at each site, completion of a river field survey sheet and observations of sightings, field signs and/or potential for protected species such as otter and water vole.

2.4.7 Invertebrate samples will be packaged, preserved and labelled on site, with species identified in situ if possible and returned alive to the watercourse in the location of capture. Any macrofauna such as fish will be returned to the watercourse immediately and noted.

2.4.8 Invertebrate samples will be returned to the laboratory for analysis within four days, or appropriately preserved in Industrial Methylated Spirit (IMS) or similar if this is not possible.

2.4.9 Invertebrate samples will be analysed and invertebrate taxa identified to mixed-taxon level, and to species level wherever possible, to allow calculation of biotic indices. Sample analysis will be subject to quality assurance (QA) by repeat analysis by a second invertebrate ecologist at a rate of one sample in ten, or one sample if less than ten samples are collected.

2.4.10 Results of invertebrate analysis will be collated and used to calculate biotic water quality indices as follows:


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• [Revised] Biological Monitoring Working Party (BMWP) index, including the calculation of Number of Scoring Taxa (NST), total BMWP score and Average Score Per Taxon (ASPT) as indicators of biological water quality;

• Lotic invertebrate Index for Flow Evaluation (LIFE) – score to indicate the susceptibility of invertebrate community to reduced flows;

• Proportion of Sediment-sensitive Invertebrates (PSI) – score to indicate the impact of sedimentation on the watercourse; and

• Whalley, Hawkes, Paisley & Trigg (WHPT) index – an updated version of the BMWP index with more accurate scores that take taxon abundance into account – to allow comparison of data with future results.

• Comparison of Observed/Expected using the River Invertebrate Classification Tool (RICT) where appropriate to provide an accurate indication of water quality.

• Species Quality Score (SQS) and Species Quality Index (SQI) where appropriate to allow comparison with previous sampling data (Boyce, 2013).

2.4.11 Data will be compared with historical water quality data (including data collected pre-construction), where available, to assess potential effects to the watercourse and identify trends in ecological water quality. Results of chemical surface water quality assessment will also be used to inform conclusions drawn from biological data.

2.5 Control and Trigger Levels NRW Trigger Levels

2.5.1 In October 2016, NRW published revised trigger levels for surface water quality to be applied to the Scheme. These can be found in Appendix 2. NRW have stated that they have been developed for use during both the construction and operational phase of the Scheme, and designed to flag one-off pollution events.

2.5.2 The Trigger Levels are predominantly based on Water Framework Directive standards, though given the unique nature of the reens should be reviewed in conjunction with the derived control levels which, as aforementioned, will reflect the sensitivity of the reens as baseline monitoring results will be used in their development.

Derivation of Control Levels

2.5.3 Water quality control levels are proposed for derivation using chemical quality data collected from all monitoring points. The control levels act as an early warning mechanism of a potential breach of the NRW Trigger Levels (Appendix 2), agreed for the Scheme. Derived control levels will be applied to the monthly results of surface water and sediment monitoring demonstrate compliance with


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the NRW trigger levels (for surface water quality) but also to identify baseline conditions and trends so that any statistically relevant deviations can be identified and contingencies put into practice before a trigger level is potentially breached.

2.5.4 Control and trigger levels for chloride will not be utilised due to the likelihood of sudden spikes in chloride pollution due to road gritting and the difficulty of altering road gritting practices during cold weather when highway maintenance staff are fully engaged on road management. The management of chloride will therefore be undertaken through the use of alternative winter road treatment agents. This is described in Section 2.6 of this report.

2.5.5 Derivation of a control levels for single determinands can be defined using multiple methods. It is proposed, depending on baseline variance, to use a rolling average (or annual average for determinands assessed for compliance on an annual average basis) plus 10%, or a rolling average plus two standard deviations to identify the point of statistically relevant deterioration. In this way, the range of natural variation of baseline conditions can be accounted for within the data sets.

2.5.6 Appendix 3 shows the statistical descriptors for the 7 rounds of quarterly monitoring data set undertaken to date. All values recorded below the laboratory limit of detection (LOD) has been taken to be zero as this represents the most precautionary position for capturing changes to baseline conditions. Both the mean + 10% and the mean plus two standard deviation concentrations are presented.

2.5.7 Should an exceedance of the defined control level be identified following a sampling round, this will trigger an immediate re-sample of the location(s) that recorded the breach.

2.5.8 Turnaround time of monthly surface water sampling should be 7 days from time of sampling to allow timely identification of any adverse trends. Should re-sampling be required, the turnaround time for the repeat sampling should be within 3 days in order to determine quickly whether the initial exceedance was anomalous (a data spike) or if further reactive measures should be initiated. Following a repeat identification of a control level breach, weekly sampling will continue to allow a detailed event time series to be gathered to help inform the assessment and until water quality conditions have stabilised. In this way, upward trend behaviour can be captured to inform the appraisal of further mitigation measures.

2.5.9 A significant control level breach will be considered to have occurred following 3 consecutive exceedances of the control level which would be captured within a period of approximate 3 weeks as summarised in Table 2.2:

2.5.10 Such an approach allows for sporadic, non-repeating fluctuations to be observed but discounted as not in themselves considered as significant or warranting immediate corrective actions.


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2.5.11 Following the identification of a significant control level breach following consecutive exceedances of a control level, corrective action would be started. This would be agreed with NRW and detailed within the Surface Water Management Plan as part of the Construction and Environmental Monitoring Plan, but would typically involve the communication of the event to concerned parties, the instigation of further monitoring to verify conditions and further investigations of the drainage catchment to identify likely causes and to propose mitigation.

Table 2.2 Monitoring and scheduling programme in relation to a breach in a control level.

Day 1 Water sampling including duplicate and schedule analysis on single sample.

Day 8 Results following a 7 day turnaround. Schedule analysis on duplicate on breach of control level with a 3 day turnaround.

Day 11 Results of duplicate. Day 12 Re-sample in field on breach of control level and Inform NRW and

WG representatives. Schedule analysis on 3 day turnaround. Day15 Results of re-sampling. Day 16 Re-sample in field on breach of control level and Inform NRW and

WG representatives. Schedule analysis on 3 day turnaround. Day 19 Results of second re-sampling. Day 20+ On continued breach of control level, inform NRW and WG

representatives. Continue sampling until water quality parameters have stabilised within acceptable limits of variability.

2.5.12 Sediment results will be compared to trigger and control levels for pollutant concentration limits as defined by HAWRAT referred to as the Threshold Effect Level (TEL) and Probable Effect Level (PEL) respectively. These concentrations are summarised in Table 2.3.

Table 2.3 HAWRAT defined TEL and PEL concentrations for sediments.

Determinand Unit Threshold Effect Level (TEL)

Probable Effect Level (PEL)

Copper mg/kg 35.7 197 Zinc mg/kg 123 315 Cadmium mg/kg 0.6 3.5 Total PAH ug/kg 1,684 16,770 Pyrene ug/kg 53 875 Fluoranthene ug/kg 111 2,355 Anthracene ug/kg 46.9 245 Phenanthrene ug/kg 41.9 515

2.5.13 In response to a breach of sediment chemical quality thresholds as defined by DMRB HARWAT and evidence of adverse effects on aquatic invertebrates, consideration would be given to the controlled removal and disposal of the effected sediment. Agreement will be sought with NRW on a contingency plan for dredging and disposing of polluted sediments as controlled wastes.


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2.5.14 Dredging and disposing of polluted sediments would not be undertaken as part of current routine dredging activities undertaken by NRW but be managed by a separate specialist contractor. This contractor would be experienced in such activities and be able to undertake these works without risking pollution of the wider reen network by remobilisation contaminated sediments by utilising best practice methods. Should this contingency measure be required, the final approach would be undertaken under an appropriate method statement agreed with NRW and under all appropriate consents.

2.6 Winter Treatment Runoff 2.6.1 Concerns have been raised through discussions with NRW regarding the impact

on surface water quality as a result of winter road treatment comprising rock salt gritting and the associated potential risk of reen salinisation.

2.6.2 The nature of the reen network and ecology associated with it has been identified as being susceptible to increased chloride concentrations. Table 2.4 provided by NRW demonstrates the range of sensitivities of British aquatic plant species and organisms to varying degrees of chloride concentrations, with many of the flora present across the Gwent Levels defined as ‘salt-intolerant species’.

2.6.3 NRW and WG have identified the potential for calcium magnesium acetate (CMA) to be strategically deployed on the motorway network to avoid salinization of reens at times of increased biological sensitivity as CMA has minimal impact on aquatic organisms.

2.6.4 Therefore, to mitigate risk of the effects of elevated chloride concentrations on sensitive biology of the SSSI during the spring, Welsh Government will deploy CMA in place of rock salt as a winter road treatment agent on the new section of motorway between 1 March and 30 September inclusive.

Table 2.4: British plant species sensitivities to chloride concentrations after Hill et al.(1990)


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2.7 Monitoring Frequencies 2.7.1 The frequency of monitoring for the aforementioned strategies is to be monthly

for the first 5 years of operation.

2.7.2 It is anticipated that the first year of monitoring will be variable and subject to agreement in order to begin definition of baseline control levels. At this stage, it is proposed that the monitoring schedule proposed in Table 1.1 will be implemented for the first 5 years of operation.

2.7.3 At the end of the first 5 years of operation this protocol will be formally reviewed in conjunction with NRW. That review would assess the data collected to date and make recommendations to continue the monitoring regime for a further 5 year period, or to amend the number of monitoring locations and/or frequency of monitoring for an agreed period, or to cease monitoring. In all cases, the outcome of the review which would be agreed with NRW as Welsh Government’s environmental adviser would be dependent on the performance of the WTAs and compliance with NRW Trigger Levels as evidenced by the data collected. Any subsequent periods of monitoring would include a formal review in conjunction with NRW.


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3 Maintenance of Water Treatment Areas 3.1.1 Maintenance of the WTA and associated drainage channels will be completed to

the standards set out within the DMRB report HA 103/06 Vegetated Drainage Systems for Highway Runoff (Chapter 6 Maintenance and Management of Vegetated Drainage Systems) (Highways Agency et al., 2006b).

3.1.2 In response to a breach of control levels, an inspection of grass lined channels and the WTA for possible causes potentially leading to the removal of silts from grass lined channels or WTA lagoons or partial regeneration of reed beds.

3.1.3 These inspections and monitoring will be especially vital during the first five years of operation to gain an understanding of drainage treatment functionality and provide evidence to NRW of adequate levels of WTA performance and hence protection of surface water quality, whilst allowing for timely identification and intervention should significant deficiencies in WTA performance occur.

3.1.4 HA103/06 provides suggestions for maintenance and management of vegetative drainage systems recognising the requirement for a more frequent level of inspection compared to conventional drainage systems. Table 3.1 summarises the HA suggested requirements whilst acknowledging these should not be interpreted rigidly.

Table 3.1. Inspection and maintenance requirements for vegetative systems

Grass Lined Channels

Attenuation Lagoon Reed Bed

INSPECTIONS Inflow/outfalls Integrity/erosion Debris/rubbish

Quarterly or after each major storm

Annually Monthly or after each major storm

Build-up of sediment or invasive weeds Annually Annually Annually

Vegetation cover/vigour Monthly or after each major storm

Annually Annually

Check for protected species Specialist advice to be sought

ROUTINE WORKS

Clearance of rubbish/debris

Monthly or after each major storm

Quarterly Quarterly

Cutting vegetation Monthly or after each major storm

5-10 year cycle and remove

1-5 year cycle and remove

Removal of plant litter N/A N/A 5-10 year cycle if required

Removal of sediment To be determined annually

To be determined annually

To be determined annually


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3.1.5 Through these inspections and maintenance, high confidence can be maintained in the design functionality of the water treatment described systems. It is therefore important that responsibilities and maintenance routines are clearly identified at an early stage.

3.1.6 A Management Plan will be prepared setting out objectives and an annual programme of intended maintenance operations. This supports Commitment No. 161 describing ongoing long term maintenance commitment transferring to Welsh Government’s highway maintenance contractor (currently SWTRA) to be documented within a Handover Environmental Management Plan (HEMP).

3.1.7 Inspection and maintenance of grass lined channels is an integral element of the Management Plan for the scheme and represents as functionality of these SuDS features is required to maintain their effectiveness for intercepting pollutants. Additionally, because this effectiveness, over time grass lined channels will accumulate pollutants within these sediments.

3.1.8 Welsh Government has undertaken a review of options for the capture and recovery of sediments from Grass Lined Channels in order to demonstrate the practicalities of this task. This review is included at Appendix 4. The review concludes that sediment removal can be undertaken routinely using specialist plant from the hard shoulder. Whilst some loss of vegetation is predicted, this can easily be rectified by reseeding as appropriate.

3.1.9 All sediments recovered from grass lined channels would be considered to be waste to be removed from the motorway for classification and disposal following appropriate chemical testing.


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4 Data Management and Reporting

4.1.1 All laboratory analytical data and physical data collected as part of the Monitoring Strategy will be collated in a database using the industry-recognised AGS data standard. This database will be validated to ensure a consistent and complete dataset is maintained throughout the project. This enables effective integration with historical datasets and the use of automated analysis techniques to quickly interrogate, visualise and report on the results of the laboratory analysis to inform future monitoring works.

4.1.2 Tabulation of the data for the three monitoring objectives will initially allow for a calculation of a baseline control level defined for each pollutant at the 95th %ile of the baseline data set or similar in agreement with NRW, in addition to screening against relevant water quality standards (for surface water).

4.1.3 Surface water quality results will be reviewed each month and screened against the control level. An exceedance will be flagged for review and a further two sampling rounds carried out at the breached location. Should three consecutive exceedances of the baseline control level occur, investigation and necessary mitigation will begin, and NRW shall be notified.

4.1.4 Annual monitoring reports will be provided to WG and NRW to present the evidence and assessment of WTA performance and any effects, attributable to WTA, on the local reen water quality and biology. The annual reporting period will commence in April to permit a full winter to be captured by each report. The report will contain all data both as laboratory reports as well as time series plots of sampling and data logger and rain gauge measurements clearly identifying control and trigger levels and a summary of any trends and exceedances. There will also be a summary of all winter treatment applications made in the reporting period and the findings of an assessment of reen sensitivity to the winter period. These reports will be undertaken in consultation with NRW and on completion be made available to the public.

4.1.5 A review report will be produced every 5 years and make recommendations on a way forward.


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| 05 May 2017

Appendices


| 05 May 2017

Appendix 1: CCW Guidance Note Four: Water Quality Monitoring on the Gwent Levels Site of Special Scientific Interest

GUIDANCE NOTE FOUR WATER QUALITY MONITORING ON THE GWENT LEVELS SITES OF SPECIAL SCIENTIFIC INTEREST COUNTRYSIDE COUNCIL FOR WALES DRAFT - SEPTEMBER 1996 INTRODUCTION The Gwent Levels SSSIs were notified for the plant and invertebrate communities associated with the reens and ditches. This interest is dependant on the quality and quantity of water in the reens and ditches and is potentially adversely affected by physical developments; CCW require effective monitoring programmes to assess these impacts. This is the fourth in a series of guidance notes on survey and monitoring on the Gwent Levels SSSIs; it details the requirements for an effective programme of water quality monitoring to achieve the following aims: 1 to identify any impacts of the development on the water quality of the SSSI; 2 to establish baseline water quality data prior to work commencing on site and to establish

appropriate threshold levels where appropriate. Monitoring points upstream or outside the area of works can provide control points during construction;

3 to monitor the water quality in the reens and ditches during construction, both quarterly at

agreed points and on an ad hoc basis; 4 to aid the interpretation of any changes identified by the invertebrate and flora monitoring

programme; 5 to act as a trigger to initiate pollution contingency measures; 6 to monitor recovery of the water quality from any adverse impacts; 7 to monitor the water quality at sites created as part of any mitigation measures. 1. SAMPLING STATIONS Sufficient sampling stations are required to adequately represent the variation in ditch management, land use and seral stage. The number of stations and their position would be dependent on the nature and design of the development project that the programme is designed to monitor. A number of stations either upstream or off the site are recommended to act as control points. In addition, sample stations should cover the following four categories: A -sites unaffected by the development; B -sites within the development area, but to remain as ditches/reens; C -sites to be infilled or diverted as a result of the development; D -sites to be created as mitigation reens/ditches.

We recommend the use of sampling stations from previous surveys/monitoring programmes wherever possible. To evaluate the range of habitats on site and to decide on suitable locations for sample points, a complete walkover survey of the study area is recommended. A map should be compiled identifying the following features: Environment Agency waterways, IDB main reens and minor field ditches;

reens/ditches with open water; reens/ditches dominated Phragmites or other emergent vegetation; location of hedgerows and mature trees; other field boundaries, e.g. walls, fences; land use, e.g. arable, grassland, buildings.

To enable sample stations to be relocated for the duration of the monitoring programme, we recommend that they are clearly identifiable, using marker posts, photographs and physical features unaffected by the development as references. In addition, we recommend plan and cross section sketches at each station are compiled to aid the recording of physical features of the reen and the precise relocation of the site. An example from Gibbs (1991) is attached. 2. TIMING Water quality sampling should be undertaken every three months. To be consistent the samples should be taken at a similar time of day and time of year throughout the programme. Water quality may also be required on an ad hoc basis, e.g. following a pollution incident. 3. SAMPLING METHODOLOGY At each sampling station it is important to record possible influencing factors, such as weather conditions, recent reen/ditch management as these may have a bearing on the results of the samples. The following parameters should be recorded on site:

Temperature (both air and water);

pH - a quantitative expression for the acidity or alkalinity of a solution;

Conductivity - a measure of the dissolved salts present in the water;

Total Suspended Solids (TSS) - high concentrations of suspended solids for prolonged periods may adversely affect the aquatic life. The subsequent settling of the sediment on the bottom substrate and on vegetation may also have an impact;

Dissolved Oxygen.

Water samples should be taken from the centre of a reen using a long handled dipper. If the dipper comes into contact with the bank or vegetation the sample should be discarded. Samples should be transferred to suitable glassware and stored in chilled containers. The dipper should be thoroughly rinsed with de-ionised water between each sample.

Samples should be transported to the laboratory for testing within 6 hours of being taken. Testing should follow standard laboratory procedures for the following determinands as appropriate:

Biological Oxygen Demand (BOD) - a measure of the oxygen demand of microbial degradation of organic matter in the water and a measure of organic pollution;

Ammoniacal Nitrogen (NH and NH) - inorganic nitrogen compounds produced in the decomposition of organic matter. Elevated concentrations are indicative of organic pollution;

Nitrate (NO3) - excessive levels of this plant nutrient may lead to excessive vegetation growth, loss of species diversity;

Nitrite (NO2) - unstable nitrogen compounds, high levels of which may provide evidence of nutrient enrichment;

Total Oxidised Nitrogen (TON) - a total measure of nitrites and nitrites ; Phosphorous - an essential plant nutrient, high levels of which can promote excessive plant growth or algal blooms. Orthophosphate is a measure of the inorganic phosphorous which is available for plant growth and naturally present in low concentrations;

Sulphates - particularly re. PFA/Blast furnace slag.

Chloride - an indicator of saline influence from, e.g. the estuary, or de-icing salts from road run-off discharges into a reen;

Calcium - a naturally occurring metallic element, usually present in ionic form. High concentrations may contribute to a high pH and conductivity.

Zinc - a potentially toxic metal and is a List II substance under the EC Dangerous Substances Directive;

Lead - lead is toxic to aquatic plants and animals and tends to be more toxic in soft water;

Cadmium - Another heavy metal substance and a List I substance;

Nickel;

Petrochemicals;

Total oils and greases.

It may not prove necessary to conduct all of the above tests at all of the stations.

4. REPORTING Results should be released quarterly as soon as the data is available. Water quality results should also be summarised in the annual report. Reports should include: The full data set of all the parameters tested at each station; Comparison of results with previous surveys if applicable; An assessment of whether development related effects on the water quality have been detected; Evaluation of the success of reen protection measures and mitigation areas; Recommendations - for alteration of construction/operational methods and for further monitoring if appropriate.


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Appendix 2: NRW Trigger Levels for the Gwent Levels SSSIs

Approved Version – 12 December 2016

Briefing note

NRW Advice on Water Quality Standards to be used for Impact Assessment of the M4 Relief Road on the Gwent Levels Ditch System Background Welsh Ministers have responsibility for motorways and trunk roads in Wales. On this basis, Welsh Government are developing proposals to build a new section of motorway between Junctions 23 and 29 of the existing M4 in Newport, a project known as the M4 Corridor around Newport (M4 CaN). The proposed route passes to the south of the existing motorway, immediately to the south of the Tata Steelworks at Llanwern, on the Caldicot Level, would involve a new crossing of the Rivers Usk and Ebbw and passes to the south of the Quins Radiator Plant, on the Wentlooge Level. Consequently the proposals fall within and would directly affect (i.e. both construction upon and drainage into the network) the northern sections of the following Gwent Levels: Sites of Special Scientific Interest (SSSIs):

Gwent Levels: St Brides SSSI

Gwent Levels: Nash and Goldcliff SSSI

Gwent Levels: Whitson SSSI

Gwent Levels: Redwick and Llandevenny SSSI In addition the following sites could potentially be indirectly affected, due to being part of the same drainage system:

Gwent Levels: Rumney and Peterstone SSSI

Gwent Levels: Magor Marsh SSSI

Magor Marsh: SSSI

Gwlyptiroedd Casnewedd/ Newport Wetlands SSSI Consultants working on behalf of Welsh Government, as part of a Joint Venture, have drawn up a preliminary design for the new stretch of motorway. This work includes a drainage strategy, designed to take surface water from the carriageway and convey it, primarily through open, grass-lined channels to a number of water treatment areas (WTAs) along the proposed route. The purpose of the WTAs is to treat water to a standard suitable for discharge into the drainage system (network of reens and ditches) of the Gwent Levels SSSIs, through treatment which includes the use of oil interceptors and reed beds.


As NRW, we need to develop a full remit view on acceptable water quality, across a range of determinants, to be discharged into the Gwent Levels SSSI drainage system. Different water quality standards apply and this paper provides advice on the most appropriate water quality standards to apply for impact assessment, taking into account:

Relevant legal frameworks and requirements.

The applicability of the relevant standards to the environment in question;

The likely impacts of road construction and operation on water quality and / or freshwater ecosystems;

Summary of Relevant Legislation The Water Framework Directive (WFD) requires European Member States to aim to reach Good Surface Water Status which comprises Good Chemical Status and Good Ecological Status (with certain exceptions and derogations possible) for all water bodies by a named deadline as outlined in the relevant River Basin Management Plan. The objectives vary according to the type of water body involved. Ecological Status is measured against environmental standards linked to the most applicable pressures in the relevant water body as identified by a risk assessment. Monitoring methods (termed classification tools) are standardised, evidence-based and inter-calibrated across member states. Article 1 of the WFD sets out its main purposes, which includes preventing further deterioration of waters and to protect and enhance aquatic ecosystems, promote sustainable use, reduce discharges, emissions and losses of priority substances. The core measures in Article 4 of the WFD are those necessary to prevent deterioration in the status of surface water, to protect, enhance and restore surface waters.

Although WFD is European level legislation and has robust, evidence-based standards, there are problems with its applicability in the Gwent Levels environment. These are discussed below;

All water bodies in the Gwent Levels system are designated as Artificial Water Bodies, and there is a lack of clarity regarding the most appropriate objectives to set for these.

The Habitats Directive (HD) requires European Member States to attain Favourable Conservation Status for certain specified Habitats and Species listed in Annexes using a combination of Protected Areas (Special Areas of Conservation – SACs) and wider territory measures.

The Gwent Levels are not a SAC and no freshwater Annex I habitats are known to occur in them. The River Usk SAC will need to be crossed by the M4 relief road but this is outside the scope of this document.

The Wildlife and Countryside Act 1981 (as amended) is the main legal mechanism for nature conservation in Wales. In the context of the Gwent Levels, the key powers are (i) the designation and management of protected sites, termed Sites of Special Scientific Interest (SSSIs) and (ii) strict protection of certain threatened species. SSSIs are designated and managed based on named habitat and / or species features which are protected in law. In many cases targets are set to determine whether management is favourable following guidelines set by the Joint Nature Conservation Committee (JNCC).


The Gwent Levels consists of seven SSSIs in a contiguous belt broken only by the Usk estuary.

The SSSIs are designated for a wide range of features (Appendix 1). These vary in their dependency on water and their sensitivity to poor water quality.

The Environmental Permitting Regulations (England and Wales) 2010 is UK legislation that aims to prevent facilities/activities from causing harm to the environment or human health. The environmental permitting regime requires operators to obtain permits for some activities in order to protect the environment so that statutory and Government policy environmental targets are achieved and to encourage regulators to promote best practice in the operation of activities.

Hydrology of the Levels The Gwent Levels are poorly connected to the Welsh river network and lie in one of the driest parts of Wales. As a consequence, much of the water they receive is in the winter, with very limited summer recharge. Most of this comes from precipitation that falls on the Levels themselves, rather than from upstream areas with higher rainfall. This means that water levels can fall markedly, especially in a dry summer, and water quality tends to deteriorate over the course of the summer as solutes become concentrated. This feature of the Levels needs to be taken into account in any consenting, because discharges that may have no effect in winter could be much more significant in summer. Any permit to discharge rainfall related surface run-off has a rainfall related emission limit and not a daily maximum volume limit, therefore volumes being discharged from the construction site should emulate natural rainfall levels. Due to the absence of flow in summer, NRW’s advice is that the design of any discharge needs to either (i) meet or exceed water quality standards in Table 2 or (ii) if these standards are already met, discharge water of equivalent quality to measured values in order to avoid deterioration. Available Environmental Standards and their Application to the Levels Three different sets of environmental standards exist, which vary substantially in the way they have been drafted. These are dealt with in turn. WFD Standards Water Framework Directive standards have been developed to measure the impact of specific identified pressures as the deviation from a reference condition. These have been developed using large datasets across the UK, and subject to UK consultation and a European level peer review process termed inter-calibration. WFD standards for the second River Basin Management Planning cycle (2015-2021) are published in the ‘Water Framework Directive (Standards and Classification) Directions (England and Wales) 2015’ and the methods published on the UKTAG website, www.wfduk.org. Under WFD, an assessment must be made to identify if a project may cause a deterioration of an element or compromise achieving the environmental objectives. If there is a risk of deterioration or that the objectives are compromised then the project may only proceed if the criteria under Article 4(7), 4(8) and 4(9) are satisfied. This would require a derogation

http://www.wfduk.org/


assessment to be undertaken by the relevant consenting body, supported by information provided by the applicant, NRW and other sources. A key difficulty with the application of WFD standards to the Gwent Levels is the relevance of different water quality standards to ditch and reen systems. UK WFD standards in freshwater are designed to apply to one of two environments: rivers or lakes. Both types of environment are naturally much better oxygenated than ditches due to the greater amount of water movement, and this means that the organisms that inhabit them are accordingly much more sensitive to low oxygen levels than ditch communities.

In NRW’s view therefore, WFD biological and chemical standards for Good Status do not automatically apply to the Levels.

However, if available monitoring data indicate that they can be applied with reasonable effectiveness1, then we will use these standards.

In contrast, thresholds for toxic substances are more or less universal across different freshwater environments. It is anticipated that usage of pesticides will be low risk during construction, but due to the extensive contaminated land around Llanwern, monitoring of metal concentrations is strongly recommended.

NRW recommends that WFD standards for metals and pesticides are applied as being the best currently available standards for these substances.

SSSI Ditch Standards The Joint Nature Conservation Committee (JNCC), in collaboration with the statutory UK conservation agencies, produced monitoring guidance for ditches and canals (JNCC, 2005) that sets out a standard approach to assessment of condition. The water quality guidance in this document is often imprecise and some of it relates to General Quality Assessment (GQA) standards that predated the Water Framework Directive. However, NRW will follow the general principle in the ditch CSM guidance that ditches in favourable condition should have clear, unpolluted water. NRW has therefore interpreted the JNCC ditch guidance to mean that water quality should meet current water quality standards and therefore the older General Quality Assessment (GQA) approach have been replaced by relevant WFD targets where applicable. In addition, CCW produced an internal set of SSSI trigger levels which were used for casework in the Gwent Levels. These are intended to be used as a means of triggering action if a one-off concentration is breached: they are not intended as measurements of favourable condition. The list of determinands and their target values have been reviewed in combination with the current WFD standards and other relevant evidence, JNCC guidance, risks from road runoff and available monitoring data to provide final advice. In general these were found to be insufficiently protective of water quality in the light of current environmental standards. Some similar determinands were also rationalised to improve efficiency. The proposed changes are summarised below:

1 ‘Reasonable effectiveness’ means that when applied to the Gwent Levels, an environmental standard gives a classification result that, in NRW’s opinion, reflects the overall environmental condition of the relevant water body taking into account the pressure being measured by that standard.


Table 1. Summary of changes to SSSI determinand trigger levels

SSSI Determinand Modification

pH Minor changes to align with WFD standard

Conductivity Tightened to align with WFD salinity standard

Total Suspended Solids Replaced with a Secchi disc measure to align with JNCC guidance and which is cheaper and simpler to monitor.

Biological Oxygen Demand Tightened to align with WFD standard

Total Oxidised Nitrogen (TON) Level unchanged, but linked to P standard to reflect potential varying nutrient dynamics.

Nitrate No longer used (included within TON).

Nitrite No longer used (included within TON).

Ammoniacal N Tightened to align with WFD standard.

Orthophosphate Tightened to align with WFD standard; also linked to TON.

Sulphates Unchanged.

Chloride Unchanged.

Calcium No longer used (include within Conductivity).

Zinc Tightened to align with WFD standard.

Lead Tightened to align with WFD standard.

Cadmium Tightened to align with WFD standard.

Nickel Tightened to align with WFD standard.

Petrochemicals Replaced with PAH standard that reflects current best practice.

Oil and Grease Tightened based on advice from water quality specialists.

Dissolved Oxygen Not used due to large natural variation.

The above approach is designed for habitats and not tailored to individual species. We expect that this approach will be sufficient to support the needs of the wide range of water dependant species features on the Levels, and have consulted with individual species specialists internally to confirm this. In most cases we expect that relevant available evidence will be limited. Differing objectives In some cases, two different objectives may apply for the same determinand, due to different approaches taken by different guidance/directions, or due to different sensitivities of SSSI features. In this case both objectives may be applied under different assessments. However, revision of SSSI trigger levels to better align with WFD standards has greatly reduced the probability of this occurring. Balance of Evidence and Use of the Precautionary Principle NRW is an evidence-based organisation. We will accordingly base our recommendations on evidence wherever this is possible, whether this is existing standards, published scientific evidence relating to sensitivity, or site-specific information. However, for some of the rarer species, especially those found on the Levels, we expect that information regarding their sensitivity to poor water quality will be inadequate or entirely lacking. In this case we may need to recommend a precautionary approach.


We will only recommend a precautionary approach when:

Potentially sensitive: There are reasonable grounds to assume that the species is sensitive to a water quality determinand, and;

No relevant standard: There is no applicable WFD standard, and;

Geographic location: A significant proportion of the population of the potentially sensitive species is likely to be affected by the activity or discharge.

Next Steps All of the above has been taken into account in developing NRW’s view on appropriate water quality standards for the Gwent Levels SSSIs, which is presented at Technical Appendix 2. The endorsement, and sign-off of the Water Management Group is now required to enable these standards to be used in connection with the M4 CaN and also in relation to other development proposals of any scale likely to impact the water quality of the Gwent Levels SSSI. Adoption of these standards will enable NRW officers working within the Gwent Levels to provide consistent and evidence based advice. There would still be an expectation that developers/applicants provide baseline water quality data relevant to their proposed development and that this would then need to be considered in relation to the principle of no deterioration. Once agreement of this approach has been reached within NRW, it would then be communicated to those working on WG’s M4 CaN project as well as those working on other development proposals within the Gwent Levels area. Update NRW’s Water Management Group endorsed the approach set out in this paper during their meeting on 17 November 2016, subject to a number of amendments which have now been completed. 12 December 2016

Technical Appendix 1 SSSI Features per Gwent Levels SSSI

SSSI Name Feature

Gw

en

t Levels

–

Mag

or &

Un

dy

Gw

en

t Levels

–

Nash

& G

old

cliff

Gw

en

t Levels

–

Red

wic

k &

Lla

nd

even

ny

Gw

en

t Levels

–

Ru

mn

ey &

Pete

rsto

ne

Gw

en

t Levels

–

St B

rides

Gw

en

t Levels

- Wh

itso

n

Mag

or M

ars

h

New

po

rt Wetla

nd

s

Standing Water (habitat)

Swamp

Marshy grassland

Independently qualifying plant species

Potamogeton trichoides (water plant – hairlike pondweed)

Wolffia arrhiza (water plant – rootless duckweed)

Carex elata (wetland plant)

Bagous tubulus (weevil

Bombus sylvarum (shrill carder bee)

Coenagrion pulchellum (variable damselfly)

Hydaticus transversalis (water beetle)

Hydrophilus piceus (water beetle)

Laccornis oblongus (water beetle)

Limnoxenus niger (water beetle)

Odontomyia ornata (fly)

Plateumaris braccata (beetle)

Anas clypeata (bird - shoveler)

Limosa (bird - curlew)

Cettia cetti (bird - Cetti’s warbler)

Tringa totanus (bird - redshank)

Vanellus vanellus (bird - lapwing)

Recurvirostra avosetta (bird - avocet)

Panurus biarmicus (bird - bearded tit)

Rallus rallus (bird - water rail)

Breeding bird assemblage of lowland open waters and their margins

Fen invertebrate assemblage

Grazing levels invertebrate assemblage

Rare Aquatic Plant Assemblage

Feature

Hab

itat (F

= fre

sh

wate

r;

WD

= te

rrestria

l bu

t w

ate

r dep

en

dan

t; T =

Terre

stria

l an

d n

ot

wate

r dep

en

dan

t)

Lik

ely

to b

e a

ffecte

d b

y

po

or w

ate

r qu

ality

Standing Water (habitat) F Y

Swamp F Y

Marshy grassland WD ?

Potamogeton trichoides (water plant – hairlike pondweed) F Y

Wolffia arrhiza (water plant – rootless duckweed) F Y

Carex elata (wetland plant) WD N

Bagous tubulus (weevil) WD ?

Bombus sylvarum (shrill carder bee) T N

Coenagrion pulchellum (variable damselfly) F Y

Hydaticus transversalis (water beetle) F Y

Hydrophilus piceus (water beetle) F Y

Laccornis oblongus (water beetle) F Y

Limnoxenus niger (water beetle) F Y

Odontomyia ornata (fly) T? ?

Plateumaris braccata (beetle) T? ?

Anas clypeata (bird - shoveler) F ?

Limosa limosa (bird - curlew) WD Y

Cettia cetti (bird - Cetti’s warbler) WD ?

Tringa totanus (bird - redshank) WD ?

Vanellus vanellus (bird - lapwing) WD ?

Recurvirostra avosetta (bird - avocet) F ?

Panurus biarmicus (bird - bearded tit) WD N

Rallus rallus (bird - water rail) F ?

Breeding bird assemblage of lowland open waters and their margins Mixed Mixed

Fen invertebrate assemblage Mixed Mixed

Grazing levels invertebrate assemblage Mixed Mixed

Rare Aquatic Plant Assemblage F Y

Technical Appendix 2 – Water Quality Standards for the Gwent Levels

Determinand Reason for Inclusion

Unit Current Values in WG sites2

WFD Standard (GES)3

SSSI Value Reference Comments

pH

Ecological impacts of high and low pH events.

pH Unit 7.12 - 8.20 5%ile >= pH6; 95%ile <= pH9.

Use WFD standard. For small datasets 6 and 9 should be used as trigger values.

WFD Directions 2015, Schedule 3 Part 1, Table 3.

Acid impacts relatively unlikely.

Conductivity Salinity standard

µS cm-1 391 - 716 Mean < 1000 Use WFD standard for lakes for routine work, and 1500 as trigger.


Road salt may be a source of pollution.

Chloride

Specific measure of road salt pollution

mg l-1 14.8 - 46.8 None 300 (maximum allowable).

SSSI trigger levels.4

Road salt may be a source of pollution.

Water clarity Smothering of plants and animals

Secchi depth

No data None

Use visual check – bed of ditch / reen should be visible at least with Secchi disc. If this is not possible, 20mg l-1 or a one-off trigger level of 60 mg l-1 suspended solids may be used.5

JNCC Ditch monitoring guidance 2005.

Water clarity is important in ditches. Replaces suspended solids target.

Biochemical Oxygen Demand (BOD)

High oxygen demand results in

mg l-1 90%ile = 6.77 (all data combined)

90%ile <5 (Good)

Use WFD Moderate or better standard. (no deterioration if H-G).


BOD is likely to be naturally higher in the Levels, but

2 Means unless stated. 3 Many WFD standards are not simple and the detail of calculating them cannot be conveyed in full in a table such as this one. Full details of all of the standards here including calculation tools and literature explaining their derivation are published on www.wfduk.org 4 WHO standard for chloride in drinking water = 250 mg l-1. British Columbia recommended guidelines for chloride in freshwaters: Max = 600 mg l-1

(Conductivity > 2133 µS cm-1) and 30-day average <150 mg l-1. 5 20 mg l-1 was previously used for the Freshwater Fish Directive. It is included here because a numerical target was requested, but visual checks are recommended as being both simpler and more ecologically relevant.

http://www.wfduk.org/

http://www.who.int/water_sanitation_health/dwq/chloride.pdf

http://www.env.gov.bc.ca/wat/wq/BCguidelines/chloride/chloride.html



WFD Standard (GES)3


dissolved oxygen sags

90%ile <6.5 (Moderate)

diffuse pollution is widespread.

Total ammonia as N

Toxic effects mg l-1 90%ile = 0.97

90%ile <0.6 (Good) 90%ile <1.1 (Moderate)

Use WFD Moderate or better standard (no deterioration if H-G)


Widespread chronic failures of GES.

Ortho-phosphate

Key plant nutrient, causes eutrophication

µg l-1 Geomean = 40.1 - 1008

Site-specific: Generally G:M boundary c 90.

Use WFD standard if possible.


Widespread chronic failures of GES.

Total Oxidised Nitrogen as N

Key plant nutrient, causes eutrophication

mg l-1 0.11 - 8.40 None.

Either or both of: (1) meets ortho-P standard above, or (2) Annual Mean TN < 2. **

NVZ criterion for lakes.

Nutrient pattern is generally that either N or P are likely to be limiting.

Sulphate

Potential for toxic effects at high concentrations

mg l-1 >300 SSSI trigger level.

SSSI trigger levels.

Scientific literature indicates variable toxicity depending on water hardness.

Zinc (bioavailable)

Toxic pollutant µg l-1 1.44 - 6.98 10.9 + ambient background6

Use WFD standard. WFD Directions 2015, Schedule 3, Part 2, Table 1.

All WG sample points currently pass.

Copper (bioavailable)

Toxic pollutant µg l-1 1.23 - 4.497 1.00 (AM) Use WFD standard. WFD Directions 2015, Schedule 3, Part 2, Table 1.


Lead and its compounds (dissolved)

Toxic pollutant µg l-1 0.06 - 1.53 1.3 (AM); 14 (MAC).

Use WFD standard WFD Directions 2015, Schedule 3, Part 3, Table 1.

1 WG sample point fails.

6 Reference background levels are available at http://www.wfduk.org/resources%20/estimation-background-reference-concentrations-metals-uk-freshwaters. A value of 5 µg l-1 (10%ile for the River Usk catchment) is recommended. 7 These are dissolved Cu values, but due to the high alkalinity, when run through the WFD M-BAT bioavailability tool, all points nevertheless pass the standard.

http://www.wfduk.org/resources%20/estimation-background-reference-concentrations-metals-uk-freshwaters



WFD Standard (GES)3


Cadmium and its compounds (dissolved)

Toxic pollutant µg l-1 0.00 - 0.13 0.15 (AM); 0.9 (MAC).



Nickel and its compounds (bioavailable)

Toxic pollutant µg l-1 0.84 - 2.90 4 (AM); 34 (MAC).



Polycyclic Aromatic Hydrocarbons (PAHs)8

Toxic pollutant µg l-1 0.00 – 0.46 1.7 x 10-4 (AM); 0.27 (MAC).

Use WFD Standard WFD Directions 2015, Schedule 3, Part 3, Table 1.

3 WG sample points fail.

Oil and Grease Toxic Pollutant mg l-1 0.00 – 3.56 None None visible. 1 mg l-1 (MAC)

SSSI Trigger Levels (adjusted)

1 WG sample point fails.

Pesticides and other Hazardous and Priority Substances identified under WFD

Toxic Pollutant Various Generally below limit of detection.

Various Use WFD standard. WFD Directions 2015

These should be included subject to the results of a risk assessment.

8 The standard refers to the sum of five different PAHs: benzo (a) pyrene which is the commonest PAH is typically used as a marker for others.


| 05 May 2017

Appendix 3: Water Quality Statistics for Current Baseline Monitoring Dataset

Location

Min Avg Max Std Dev Avg + 10% Avg + 2xStdDev

General ParameterspH <1 6 - 9 pH Units 7.98 8.21 8.35 0.13 9.03 8.47Electrical Conductivity <0.005 1500 uS/cm 500.60 500.60 500.60 # 550.66 #

Total Suspended Solids <2 60 mg/l 4.50 5.86 17.50 6.67 6.44 19.20

Chloride <2 300 mg/l 30.00 33.72 40.80 4.52 37.09 42.76

Metals (dissolved, filtered)**Copper (bioavailable) <0.85 1.00 AM ug/l 0.95 0.91 1.86 0.68 1.00 2.28

Zinc (bioavailable) <1.3 10.9 + ambient background ug/l 1.49 3.27 6.36 1.88 3.60 7.03

Metals (total, unfiltered)

Cadmium <0.50.15 (AM); 0.9 (MAC).(dissolved)

ug/l 0.00 0.00 0.00 0.00 0.00 0.00

Petroleum HydrocarbonsTPH / Oil & Greases <1 1 mg/l 0.00 0.00 0.00 0.00 0.00 0.00Other Organic Compounds

PAH (Total Detected USEPA 16) <0.3441.7 x 10-4 (AM);

0.027 (MAC). ug/l 0.36 0.18 0.70 0.30 0.20 0.77

AM = Annual Mean

Parameter Units1.1

NRW Trigger Level<LOD

WTA 1 - Pwll Bargoed Reen

Location

General ParameterspH <1 6 - 9 pH UnitsElectrical Conductivity <0.005 1500 uS/cm

Total Suspended Solids <2 60 mg/l

Chloride <2 300 mg/l

Metals (dissolved, filtered)**Copper (bioavailable) <0.85 1.00 AM ug/l

Zinc (bioavailable) <1.3 10.9 + ambient background ug/l



ug/l

Petroleum HydrocarbonsTPH / Oil & Greases <1 1 mg/lOther Organic Compounds


0.027 (MAC). ug/l

AM = Annual Mean

Parameter UnitsNRW Trigger Level<LOD


7.15 7.66 8.09 0.36 8.43 8.38549.60 549.60 549.60 # 604.56 #

2.50 7.21 31.50 11.33 7.94 29.88

33.90 46.83 54.30 7.40 51.52 61.63

0.88 0.94 2.47 1.00 1.04 2.95

0.94 2.25 5.81 1.67 2.48 5.59

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

6.21 1.04 6.21 2.54 1.14 6.11

2.2

WTA 2 - Tyn-y-Brywn Reen

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean



6.99 7.35 7.56 0.20 8.08 7.75391.20 391.20 391.20 # 430.32 #

2.50 4.79 26.50 9.73 5.26 24.25

11.60 34.05 127.00 45.58 37.46 125.21

0.91 0.84 2.65 0.97 0.92 2.78

1.12 4.76 14.70 4.96 5.24 14.68

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

5.2

WTA 4A/4B - Percoed Branch East

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean


WTA 5 - Morfa Gronw Reen

7.3


6.77 7.22 7.61 0.32 7.95 7.86366.90 495.05 623.20 181.23 544.56 857.51

6.00 113.14 748.00 280.01 124.46 673.17

16.60 29.44 38.40 10.42 32.38 50.27

1.50 2.57 5.57 2.20 2.83 6.98

2.21 9.19 23.40 7.58 10.11 24.34

0.00 0.00 0.00 0.00 0.00 0.00

3.56 0.71 3.56 1.59 0.78 3.90

5.70 0.81 5.70 2.15 0.90 5.12

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean


WTA 6 - Lakes Reen


7.00 7.20 7.43 0.16 7.91 7.51535.15 574.08 613.00 55.05 631.48 684.17

2.50 13.21 38.50 12.15 14.54 37.52

20.00 34.05 50.40 12.72 37.46 59.49

0.87 1.36 5.32 2.09 1.50 5.55

1.31 5.29 14.00 4.89 5.81 15.06

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

12.2

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean



6.97 7.28 7.81 0.32 8.00 7.91527.00 623.50 689.30 85.39 685.85 794.29

5.00 25.60 71.50 24.19 28.16 73.99

13.50 35.37 54.70 16.43 38.90 68.22

2.07 0.78 2.61 1.22 0.86 3.22

0.47 2.67 7.57 3.09 2.93 8.86

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

WTA 7 - Julians Reen

13.1

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean



6.99 7.31 7.75 0.28 8.04 7.87352.24 381.97 411.70 42.04 420.17 466.06

11.50 35.50 120.00 42.00 39.05 119.49

16.50 22.40 31.40 6.54 24.64 35.48

1.18 0.42 1.32 0.65 0.46 1.71

0.94 1.68 2.87 0.72 1.85 3.13

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

WTA 8 - Ellen Reen

14.1

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean



7.06 7.55 8.02 0.43 8.31 8.41371.10 395.60 420.10 34.65 435.16 464.90

4.50 21.20 65.50 25.45 23.32 72.11

15.30 20.35 26.00 4.38 22.39 29.12

1.08 0.57 1.79 0.83 0.63 2.22

0.89 2.19 6.25 2.43 2.41 7.05

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

WTA 8a - Blackwall Reen

15.2

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean

Parameter UnitsNRW Trigger Level<LOD17.1


7.24 7.47 7.98 0.27 8.21 8.01506.90 506.90 506.90 # 557.59 #

2.50 23.93 132.00 48.04 26.32 120.01

14.30 32.40 41.00 9.47 35.64 51.33

1.36 2.41 5.08 1.69 2.65 5.80

1.34 3.60 15.20 5.18 3.96 13.96

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

WTA 9 - Middle Road Reen

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean

Parameter UnitsNRW Trigger Level<LOD18.1


7.12 7.29 7.67 0.21 8.02 7.70531.00 623.90 716.80 131.38 686.29 886.66

4.50 47.79 121.00 41.83 52.56 131.44

13.80 37.00 51.50 15.37 40.70 67.75

0.98 1.25 4.87 1.74 1.37 4.73

0.99 2.98 9.73 3.40 3.28 9.79

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

WTA 10 - Rush Wall Reen

Location








ug/l



0.027 (MAC). ug/l

AM = Annual Mean

Parameter UnitsNRW Trigger Level<LODMRWTA


7.70 8.13 8.29 0.23 8.94 8.59306.90 306.90 306.90 # 337.59 #

3.00 15.25 59.00 22.61 16.78 60.46

13.90 14.78 15.50 0.61 16.26 16.00

0.87 0.55 1.46 0.64 0.61 1.83

0.71 1.93 5.38 1.90 2.13 5.74

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00

0.60 0.60 2.97 1.19 0.66 2.97

WTA 11b/11c - Mill Reen


| 05 May 2017

Appendix 4: File Note - Grass Lined Channels Maintenance

File Note

GRASS LINED CHANNELS MAINTENANCE

Page 1 of 5

Project title M4 Corridor around Newport 242707

cc File reference

Prepared by:

Mike Finlay

Date

7 April 2017

Subject i

Grass Lined Channels Maintenance

1. Summary

This document reviews the grass lined channels, as published for the M4CaN scheme, alternatives and maintenance requirements. Grass lined channels, as shown in the published M4CaN scheme are the preferred option, as argued in this document. The grass lined channels will be inspected annually to assess the depth of accumulated silt and review any potential requirements for remedial measures (e.g. areas that may need reseeding). Remedial measures will be taken in accordance with the agreed procedures contained in the maintenance manual for the drainage system. At the same time, after the inspection, a decision will be made as to whether the accumulated silt requires removal (in line with the maintenance manual based on the requirements of the DMRB).

Grass would be maintained at the optimum length of 75mm and it is anticipated it will require cutting three times per year (in line with the maintenance manual based on the requirements of the DMRB).

The grass lined channels will have a maximum depth of 50mm of topsoil in accordance with the requirements of DMRB HA 119/06.

Removal of the accumulated silt will be carried out using specialist equipment.

2. Description Of Channels from the Drainage Strategy Report

The following is taken from the Drainage Strategy Report

“It is proposed to intercept the run-off from the new section of motorway into grass lined channels in the verge. These are trapezoidal shaped and are typically 2.1m wide, widening to 3.0m by 0.8m deep near outfall points. Side slopes would be 1 in 1.5. These route surface water overland from the drained carriageway to the water treatment areas. When the carriageway is super elevated in the central reserve of the motorway, the introduction of concrete barriers and maintenance restrictions excludes the use of grass lined channels. Here concrete channels will be utilised.

The grass lined channels will be dry during dry weather, enhancing their pollutant removal capability, but during a rainfall event the water will flow into them from the carriageway and move slowly to the outfall point. The flow of water will be retarded and filtered by the grass. Sediment will be deposited and oily residues and organic matter retained and broken down in the top layer of the soil and vegetation. The use of grass lined channels has been identified as a means of reducing pollution and promoting a more sustainable drainage system compared to conventional drainage systems.

christine.tucker

Typewritten Text

M4CaN-DJV-GEN-ZG_FN-EN-0002

File Note7 April 2017


Page 2 of 5

The grass lined channels will follow the gradient of the new section of motorway, typically 1 in 7,000 (after review this was revised to 1 in 2,000) through the levels. It is anticipated that they would be lined with a geo-synthetic clay liner below 50mm of topsoil. This eliminates the risk of surface water run-off containing possible pollutants seeping into the underlying ground.

The very flat longitudinal gradients across the Gwent Levels would exclude the use of kerb and gully and a piped drainage system because the longitudinal falls necessary for this system could not be achieved in an efficient way.

SWTRA have proposed that they would maintain the grassed channels using self-propelled or remote control mowers. These would require cutting 3 times a year in late spring, summer. Grass length should not be longer than 75mm in accordance with DMRB HA 119/06”

Drawing M4CaN-DJV-HDG-ZG-GEN-DR-CD-0201 shows Typical Edge of Carriageway Details. Including the grass lined channels.

3. Extracts from DMRB HA 119/06

“12.1 Ideally, for optimum hydraulic performance, the grass blades should be no longer than 75mm. The mowing regime should be developed accordingly. It is anticipated that the grass should be mown three times during late spring and summer.

12.2 The grassed channel profile should be capable of being mowed using the same equipment that is used to maintain the verge.”

4. Extracts from DMRB HA 103/06

“6.6 A Management Plan / Manual should be prepared to set out the system’s objectives, formulate an annual programme of maintenance operations and provide opportunities to review the behaviour of the system. This may be undertaken by inspection of the operation of the various elements.”

For the accumulation of sediment in the grass lined channel, Table 6.1 in the DMRB HA 103/06 suggests an annual inspection and the requirement for sediment removal being determined annually.

5. Silt Removal Options

A. Grass Lined Channels as DesignedThe grass lined channel is currently proposed, with a grass length of 75mm. The flow of water into the grass lined channel will be the same along the length of the channel. The approximate anticipated flow rate within the grass lined channel of 0.1-0.2m/s is extremely low and the silt material carried into the grass lined channel will be deposited as soon as it enters the channel. It is not expected that the silt will be carried any distance along the grass lined channel.

The grass lined channels will have a maximum depth of 50mm of topsoil in accordance with the requirements of DMRB HA 119/06.

With annual inspections of the silt depth along the length of the grass lined channel, the assessment as to whether silt removal is required will also be made on an annual basis. The channel has been designed for the 1 in 100 year storm with an additional 30% to cope with climate change over the next 100 years, which allows for observation of silt build up over the first year without compromising the channel capacity. Specialist plant is available for removal of silt from the channels, whilst



Page 3 of 5

standing on the hard shoulder. This could however cause some damage to the grass, which may require some reseeding after the silt is removed, but would form part of this maintenance regime.

It is anticipated that the accumulated silt may also gather in one or two critical areas, which will not be identified until the annual inspection regime is in place.

B. Gullies in Base of Grass Lined Channels

In order to collect the silt anticipated over a one year period, there would be a requirement for 600mm wide by 1000mm long by 750mm deep catch pits at 50m centres along the length of the grass lined channel. These pits would require to be cleaned out annually using gully suckers.

This option does not improve Option A as there is some concern that with an approximate flow rate of 0.1-0.2m/s the silt will not be carried to the gullies but will settle out in the grass lined channel and there would be the same requirement to inspect and clear the grass lined channel at regular intervals. This would however be made more difficult due to the presence of the gullies.

C. Channel at Edge of Carriageway

The formation of a 150mm wide linear concrete channel 100mm deep along the edge of the carriageway, with cross walls at 3000mm centres to preclude longitudinal flow. This channel would intercept the water flow from the motorway and allow silt to gather in the channel before the water enters the grass lined channel. The concrete channel would have to be inspected and cleaned out at regular intervals to remove the accumulated silt.

This option does not improve Option A as it would not preclude the requirement to inspect the grass lined channel annually to assess if any silt accumulation is occurring. However, we would expect that the linear channels will collect the majority of the silt.

D. Kerb at the Edge of the Grass Lined Channel

Provision of a kerb (HB2/45 degree splay) running along the top of the grass lined channel would provide an additional 75-125mm freeboard (dependent upon the type of kerb used). This would provide additional protection, to allow for the accumulation of silt in the grass lined channel. This option does not improve Option A as it has the adverse effect of making the maintenance of the grassed areas more difficult, makes the construction more difficult (geosynthetic clay liner would need to be tied into the kerb) and the grass lined channel currently already has approximately 30% overcapacity.

6. Conclusions

Given the fact that the grass lined channel is at present day designed to accommodate 30% more rainfall than above the current 1 in 100 year storm and the actual accumulation of silt can only be correctly determined by inspection of the working channel, it is proposed that the existing solution, as shown on the drawings (Option A) is the best and should be adopted, all of the alternatives having disadvantages.

An item will be added to the Commitment Schedule confirming that an Inspection and Maintenance Schedule for the drainage system (based on the suggested requirements given in the DMRB) will be produced and available at the opening of the new motorway.



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PUBLIC INQUIRY DOCUMENTbailey.persona-pi.com/Public-Inquiries/M4-Newport/E - PI...PUBLIC INQUIRY DOCUMENT REFERENCE NO. : ID/054 revised RAISED BY: Matthew Jones DATE: 19/05/17