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DCWW’S COASTAL INVESTIGATIONS PROGRAMME
Paul Taylor - Principal Consultant, Intertek18th July 2018, London
CIWEM Diffuse Pollution Conference
PRESENTATION OVERVIEW
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Background
DCWW’s Coastal Investigation Programme
Conclusions and Future Challenges
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BACKGROUND
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• Huge investment in asset infrastructure since the early 1990s
• AMP1 and 2:
• UWWTD – improved treatment levels
• New long sea outfalls
• By AMP3:
• Investment in large coastal WwTWs complete so focus moved toward investment in CSOs (UIDs)
• Need for catchment-based solutions recognised
• AMP5:
• Concerns over UWWTD saw a return back to prescriptive solutions
• AMP6:
• Ethos of evidence-based solutions to deliver the required environmental outcomes, rather than a series of capital-based outputs
• Drive for efficiencies: recognising longer term total expenditure (TOTEX) of solutions and the need to avoid over-engineering
ASSET MANAGEMENT PLANNING
ENVIRONMENTAL LEGISLATION
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• Water Framework Directive:
• Includes Bathing and Shellfish Waters
• To protect human health
• Tighter standards:
• 2006 BWD new classification
• WFD requires member states to endeavour to achieve the Guideline Flesh standard
• Guideline - 300 EC/100g flesh (Class A – 230 EC/100g)
• Class B – 4600 EC/100g flesh
• EA’s Shellfish Water Quality policy was:
• geomean of 112 EC/100ml – Class B
• geomean of 5 EC/100ml – Guideline (proposed)
• Difficult, if not impossible to achieve
IMPROVEMENTS AND FUTURE COMPLIANCE
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• Significant investment over last 30 years
• Steady improvement in water quality:
• No. of Poor BWs reduced from 25% to >5%
• No. of A & B shellfish beds increased from 55% to 88%
• But further improvements harder, and probably not possible by asset investment alone
• Diffuse pollution becoming increasingly more important
To fully understand what can be achieved and how best to do it, we require detailed holistic catchment-based
integrated modelling assessments
Swansea Bay BW
— Large urban catchment
— CSOs close to BW
— Large rivers
— Streams with misconnections
— Investment began AMP1
– New rising main
– New WwTW
– 3.5 km LSO
– UV
— Improvement in bathing water quality
AMP5 INVESTIGATION AT SWANSEA
Desired outcome
• Reduce risk of BW failure
• Improve to Good
AMP5 Investment
• NEP - 10 CSOs in Sketty, Singleton
• Additional investment in Mumbles and Swansea foreshore
NRW work on misconnections
How do we get to Excellent?
Diffuse pollution becoming increasingly more important
Tawe River, 20.2%
Clyne River, 18.5%
Singleton Park
Stream, 17.3%
Sketty CSOs, 2.5%
Singleton Park CSOs,
12.6%
Mumbles CSOs, 0.0%
Foreshore CSOs,
0.1%
Tawe CSOs,
10.1%
CSO 989, 1.6%
Knab Rock CSO,
5.3%OTHERS,
11.8%
AMP5 Improvements
‘Good’
Tawe River,
10.5%
Clyne
River,
9.7%
Singleton Park
Stream, 9.7%
Sketty CSOs,
12.7%
Singleton Park
CSOs, 7.7%Mumbles CSOs, 7.0%
Foreshore
CSOs,
10.4%
Tawe CSOs, 6.2%
CSO 989, 13.3%
Knab Rock
CSO, 4.9%
OTHERS, 7.9%
AMP5 Baseline
‘Sufficient’
DŴR CYMRU WELSH WATER: COASTAL INVESTIGATION PROGRAMME
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AMP6 COASTAL INVESTIGATIONS
• £8M programme of scientific investigations
• Two year programme (2015 - 2017)
• 49 coastal locations
• 29 bathing waters
• 20 shellfish waters
• Understand water quality pressures and impacts
• Better characterise all sources
• Quantify DCWW’s contribution
• Solid knowledge base for investment decisions:
• protecting public health and the environment
• responding to climate change
• affordable bills
Project Programme board
Coastal WQ Specialists
Survey Specialists
Alliance Partners
Steering Group
Internal Stakeholder Group
Regulator
Specialist Advisors and Auditors
External Stakeholders
PROJECT TEAM
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• Large team of several consultancies
• Collaborative planning meetings
• Focussed technical discussion meetings
• Cross-team guidance documents
• Ongoing discussions with NRW
• Consultation with local DCWW operators and NRW environment officers
• Training sessions
• Delivery partners
• Regulator
• Workshops
• Presentations and conferences
• Technical papers
• Innovative techniques developed through broad technical team
COLLABORATIVE WORKING & STAKEHOLDER ENGAGEMENT
PROJECT OVERVIEW
• Source characterisation• identify and quantify sources
• extensive field surveys
• network modelling
• EDM data analysis
• asset inspections
• Coastal modelling• new suite of hydrodynamic coastal models
• compliance (impact) assessment
• source apportionment
• Needs assessment• different assessment levels based on requirements
• identify key sources
• outline solutions
Tawe River,
10.5%
Clyne
River,
9.7%
Singleton Park
Stream, 9.7%
Sketty CSOs,
12.7%
Singleton Park
CSOs, 7.7%Mumbles CSOs, 7.0%
Foreshore
CSOs,
10.4%
Tawe CSOs, 6.2%
CSO 989, 13.3%
Knab Rock
CSO, 4.9%
OTHERS, 7.9%
SOURCE SURVEYS
• River sampling diffuse concentrations (150 sites)
(summer and winter)
• River gauging flow (60 sites)
• WwTW sampling DCWW inputs (70 sites)
• Meteorology rain and wind (12 sites)
• Phage tracer transport and connectivity (6 areas)
MARINE SURVEYS
• Fixed ADCP tidal currents (15 sites)
• Boat mounted ADCP estuaries and bays (10 sites)
• Drogues connectivity (9 sites)
• Dye tracer diffusivity (9 sites)
• Vertical profiles stratification (20 sites)
COASTAL MODELS
• Regional ‘Irish sea’ Model
• Five Local Area Models
• Delft3D Software
• Strong track record
• Proven, reliable, flexible
• Shareware, no licensing issues
COMPLIANCE ASSESSMENT APPROACH
• Proven track record: regulator approved
• Detailed compliance assessment using Intertek’s STORM-OPTIMISER software
• Integrates sewer network modelling, river catchment modelling and coastal modelling
• Full range of environment conditions (wind and tides) represented
• All sources modelled independently
• Total water quality impacts modelled for comparison against relevant environmental criteria
• Proportional contributions from each source calculated
• Sensitivity testing to handle uncertainties
• Potential solutions can be readily tested, including climate change
EXAMPLE OUTPUT: VALIDATION
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SFW Assessment Point
Classification based on shellfish flesh sample
data
Indicated classification based on model
predictions
Class Class
Dee East SFW
MP702 B B
MP1170 B B
MP1217 C C
MP1235 B B
Dee West SFW
MP1292 B C
MP697 B B
MP868 B B
MP1771 B B
MP790 B A
NB: yellow shading indicates class B, blue shading indicates class A.
SFW Assessment point
55 EC/100ml Threshold
Sampling data compliance (%)
Predicted compliance (%)
95% confidence interval on sampling data compliance (%)
MP720
Bathing Season 94 94 74 - 99
Winter Season 82 77 64 - 92
MP711
Bathing Season 100 93 74 - 100
Winter Season 80 78 61 - 91
EXAMPLE OUTPUT –COMPLIANCE AND SOURCE APPORTIONMENT
19Class B – 1500 EC/100ml (97%ile)
Class A – 55 EC/100ml (90%ile)
EXAMPLE OUTPUT –DIFFERENT SOLUTION OPTIONS
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Class B – 112 EC/100ml
Guideline – 5 EC/100ml
CONCLUSIONS AND FUTURE CHALLENGES
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SUMMARY OF CONCLUSIONS
• Programme completed on time and budget
• All 49 NEP outputs delivered to satisfaction of NRW
• Some assets identified for further investment in AMP7
• Some further investigations identified
• Majority of sites significantly impacted by diffuse
sources – including urban sites
• Agreed with NRW that asset investment alone not
justified (disproportionate costs) and would not deliver
the required environmental improvements
• Diffuse sources key to achieving Class A shellfish and
Excellent BW classification at most sites.
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• Recent reduction in sampling frequency may put BW compliance at risk
• Norovirus or other viral standards – likely to significantly impact shellfish industry
• Improved measurement techniques
• Better beach management through prediction systems
• Active Shellfish Management
• Climate Change
FUTURE CHALLENGES & OPPORTUNITIES
KEY MESSAGE
• Advances in modelling techniques since AMP1 have lead to greater certainty and understanding
• Catchment-wide holistic assessments, can deliver evidence-based conclusions to support better investment decisions and greater environmental improvements
• Diffuse sources of pollution are a significant contribution to bathing and shellfish waters in many cases – in urban areas as well as rural catchments
In order to meet the challenges of the future, pragmatic approaches, developed in partnership with all stakeholders will be necessary.
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Guideline - 300 EC/100gGuideline - 300 EC/100g
