Cyngor Bro Morgannwg
Vale of Glamorgan Council

1. Introduction
I submit this statement as an individual directly affected by the implications of the RLDP proposals for Dinas Powys. My concerns relate to transport capacity, mitigation, air quality, sustainable transport, and the adequacy of the flood risk evidence. Across all these areas, the Plan relies on incomplete, outdated or generic material which does not reflect known local conditions.

2. Traffic Capacity
The RLDP does not demonstrate that the Dinas Powys highway network can support the proposed development levels. Congestion on Cardiff Road, St Andrew’s Road, the A4055 and associated junctions is already severe during peak hours.
No settlement specific junction modelling, peak hour assessments or baseline congestion data are published. Without these core datasets, it is impossible to verify the assumption that growth can be accommodated without significant capacity impacts. The cumulative effect of allocations therefore remains untested.

3. Mitigation Measures
The Plan fails to identify clear mitigation for the traffic impacts expected in Dinas Powys. Proposed measures are broad and lack certainty regarding:
• the specific interventions proposed,
• their phasing,
• whether funding is confirmed, and
• how delivery and enforcement would be secured.
There is no guarantee that necessary mitigation will be delivered in advance of development, undermining the Plan’s effectiveness.

4. Air Quality Impacts
The RLDP does not provide a sufficiently detailed assessment of air quality impacts arising from increased traffic in Dinas Powys. No location specific modelling or clear cumulative scenario testing is published.
There is no evidence that worst case conditions have been evaluated or that the Plan can ensure continued compliance with statutory air quality thresholds. The lack of robust analysis means potential impacts on public health and sensitive locations remain uncertain.

5. Sustainable Transport Delivery
While sustainable travel is promoted in principle, the RLDP provides no firm commitments for Dinas Powys. The Plan does not identify the specific schemes to be delivered, the level of funding secured, or when improvements will be implemented.
Given the absence of detailed and deliverable measures, the modal shift assumptions underpinning the Plan are not justified. Without realistic alternatives to car use, traffic and air quality impacts are likely to be greater than the Plan assumes.

6. Flood Risk and Outdated NRW Evidence
A further and significant concern is the absence of up to date flood mitigation evidence for Dinas Powys. The RLDP relies on information that predates the major flood event of 23 December 2020 and does not incorporate any post event modelling or revised strategy by Natural Resources Wales (NRW). This represents a critical soundness failure.
6.1 Reliance on Outdated Strategic Material
The Vale of Glamorgan’s Local Flood Risk Management Strategy (LFRMS) is dated December 2013 and identified Dinas Powys as an area of “significant future risk.”
However, this strategy is now over a decade old and predates both the 2020 flood and the updated climate change projections that followed.
6.2 Pre Flood Rejection of a Strategic Scheme
In September 2020, NRW completed an Environmental Constraints and Opportunities Record (ECOR). This assessment concluded that NRW was “unable to justify a capital flood scheme” for Dinas Powys, deeming it only “marginally cost beneficial.” NRW stated it would continue with “business as usual”, limited to manual channel clearing.
This decision was made three months before the December 2020 event which flooded 98 properties internally, clearly invalidating the assumptions underpinning the ECOR conclusions.
6.3 No Post Flood Mitigation Review
Although NRW carried out flood reconnaissance in January 2021 and contributed to the Section 19 Flood Investigation Report (published November 2021), these documents are investigative rather than strategic.
Critically:
• The Section 19 report explicitly states that no catchment wide hydraulic modelling has been undertaken using the actual data from the 2020 flood.
• The report’s recommendations include asking NRW to “consider the viability of options to reduce flood risk,” confirming that no updated mitigation strategy had been developed as of late 2021.
As of now, NRW has not produced any new catchment model or revised mitigation plan for Dinas Powys that incorporates the 2020 event.
6.4 Implications for RLDP Soundness
The RLDP does not include any analysis of the 2020 flood event and does not require developers to address its implications. Without an updated NRW approved model that incorporates the most significant flood event in local memory, the Council cannot demonstrate that additional development—particularly the proposed 250 dwellings—will not increase flood risk within the catchment or elsewhere.
The flood evidence base supporting the RLDP is therefore functionally obsolete and cannot form the basis of a sound spatial plan.

7. Evidence Gaps and Overall Soundness
Across transport, air quality, sustainable travel and flood risk, there are major evidence gaps which undermine the RLDP’s justification and effectiveness. The absence of robust, transparent, and up to date assessments means the Plan does not meet national policy requirements.
In particular:
• No junction capacity modelling or peak hour traffic assessments,
• No cumulative air quality modelling,
• No defined or enforceable mitigation strategy,
• No committed sustainable transport delivery plan, and
• Flood evidence based on material rendered invalid by the December 2020 event.
Given these shortcomings, the RLDP cannot be considered sound as applied to Dinas Powys.
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8. Conclusion
The RLDP does not demonstrate that proposed growth in Dinas Powys can be accommodated safely or sustainably. Significant gaps remain in the evidence relating to traffic capacity, mitigation delivery, air quality, sustainable transport, and flood risk.
Until these deficiencies are addressed—particularly the lack of updated NRW flood modelling and the absence of settlement specific transport evidence—the Plan should not be found sound.