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Did they knew the floods would come to Mountain Ash at some time?

Everyone is aware of Storm Ciara and then Storm Denis that brought devastation to many parts of the county but especially to the south Wales valleys Rhondda Pontypridd and Mountain Ash was again flooded.

Was this was an exceptional storm that caused so much damage or is something we will have to get used to and what we can expect in the future if the last few years are anything to go by. In 2018 Wales had been battered by Storm Callum with the River Cynon has flooded at several points as this time bringing rail travel non-existent in or out of Cynon Valley, it would appear 80% of the rail line serving Cynon Valley lies in the flood zone and many homes in Cynon Valley were flooded.

 

Photos of Mountain Ash after Storm Denis show the effect water can have and the destruction it causes the one that surprised me and others was how far-reaching the flood was and concern for the new site for the £4 million Primary Care Centre at Mountain Ash. Question is will this area flood again? Well, the Primary Care Centre site sits in a flood zone as it was well documented as can be seen below. Mountain Ash has a long history of flooding, the flooding at Henry Street is well documented at The National Archives, Kew as this photograph shows take from Bernard Baldwin MBE Mountain Ash and Penrhiwceiber Remembered in Picture.  

   

  

 

Work on the new £4 million Primary Care Centre Mountain Ash has commenced, the new purpose-built facility, which is hoped to be completed in 2020-21, will become home to two local GP practices, as well as a range of community services delivered by District Nurses and Health Visitors. The 1,253 square meter site will provide a modern state of the art space for the two practices which will enable a greater range of services to be delivered to patients within a community setting.

 

 

 

Flooding December 1960

Primary Care Centre Mountain Ash site appraisal

 

The River Cynon is also located to the north of the site and, as a result, the site sits within Flood Zone C1 of NRW’s Development Advice Maps. The site is located within the recently designated Mountain Ash Town Centre Regeneration Framework (November 2018) and is specifically included as part of a number of projects that include Rhos (Guto) Square, the Mountain Ash Cross Valley Link, the Town Centre Maintenance Grant, the Community Hub and the redevelopment of 1-4 Oxford Street.

 

CONSULTATIONS

 

RCT (Internal)

Drainage Section – no objections

Public Health & Protection – no objections

 

External

NRW – Has “significant concerns” in respect of flooding.

 

Policy AW2 – The policy ensures that development proposals are only supported

when located in sustainable locations.

Such locations:

5) are justified if within TAN 15 Zone C floodplains; and

6) support the roles and functions of the Key Settlements.

 

Technical Advice Note (TAN) 15: Development and Flood Risk 2004

This document outlines a precautionary framework for the assessment of development in sites considered to be at risk of flooding. It outlines the planning requirements and acceptability criteria for development in each of the flood zones. It outlines a general resistance against residential development in flood risk zone C and that emergency services development should only be permitted in Zone C1 if determined by the Local Planning Authority, to be justified in that location.

 

REASONS FOR REACHING THE RECOMMENDATION Section 38(6) of the Planning and Compulsory Purchase Act 2004 requires that planning applications should be determined in accordance with the provisions of the Development Plan unless material considerations indicate otherwise. Furthermore, applications that are not in accordance with relevant policies within the plan should not be allowed, unless material planning considerations justify the grant of planning permission. It is considered that the principal considerations in the determination of this application are: design and place-making, transport and highway safety, conformity with the development plan and other planning policy and guidance, any ecological interest on the site, the potential for contamination of the river (proximity) and (perhaps of greatest significance) flood risk (having regard to the advice contained within TAN15 - Flood Risk and Development). If Committee is minded to approve the application it will be necessary to include a time limit for the consent to be implemented (this is added to ALL consents). Members will note from APPENDIX 1 that the applicant has a tight timescale for the construction and it is planned that construction works will commence in the near future. While it is open to Committee to grant a shorter or longer period this is rarely done and it is considered reasonable to add the “standard” condition which allows 5 years – although this will not preclude commencement of the scheme immediately upon discharging any “pre-commencement” conditions.

 

Policy Considerations

The site is located within a zone C1 floodplain and the proposal meets the definition

of ‘highly vulnerable development’ as set out in TAN 15 (Development and Flood Risk).

TAN 15 states that such a proposal can only be situated within zone C1 where certain justification is met. This includes the following:

• Its location in zone C is necessary to assist, or be part of, a local authority regeneration initiative or a local authority strategy required to sustain an existing settlement; and

• It concurs with the aims of PPW and meets the definition of previously developed land; and

• The potential consequences of flooding for the particular type of development have been considered, and in terms of the criteria contained in sections 5 and 7 and appendix 1 found to be acceptable.

Mountain Ash Town Centre was the subject of the Mountain Ash Town Centre

Regeneration Study – Phase 2 Final Report (2002) which was in force at the time that the LDP was being prepared. It is now the subject of a new Local Authority Regeneration Strategy (Mountain Ash Town Centre Regeneration Framework – November 2018).

Although the proposed health centre was not specifically included as an element of the first regeneration strategy, the proposal would have assisted the strategy by helping to sustain the settlement, through (a) enabling provision of better health services, and (b) through providing a prominent gateway building on the southern main approach to the retail centre that would enhance perceptions of the settlement. This would have been a material planning consideration in assessing the first application for this facility back in 2006/7. The current regeneration strategy specifically includes this site and allocates it for the use that is being proposed but, would still provide the same stated benefits. Furthermore, Henry Street was built as a regeneration project on disused railway sidings to an alignment designed to create the application site as a development opportunity.

The site has been identified for development for the last 17 years and it is considered that it meets the definition of brownfield development (previously developed land) as set out in PPW10. It is considered that the “justification test” set out in TAN 15 is therefore clearly met, provided that the FCA submitted in conjunction with the application is considered acceptable in accordance with Section 7 and Appendix 1 of

TAN 15.

Appendix 1 of TAN 15 advises that “Any new development on a flood plain will generally result in additional risks. The main criteria for deciding whether such a development is acceptable will depend on whether those factors can be effectively managed”

It further advises “To satisfy these criteria a site should only be considered for development if the following conditions can be satisfied;

• Flood defences must be shown by the developer to be structurally adequate under extreme overtopping conditions

• The cost of future maintenance for all new/approved flood mitigation measures, including defences must be accepted by the developer and agreed with the Environment Agency (NRW now)

• The developer must ensure that future occupiers of development are aware of the flooding risks and consequences

• Effective flood warnings are provided at the site

• Escape/evacuation routes are shown by the developer to be operational under all conditions

• Flood emergency plans and procedures produced by the developer must be in place

• The development is designed by the developer to allow the occupier of the facility for rapid movements of goods/possessions to areas away from the floodwaters

• Development is designed to minimise structural damage during a flooding event and is flood proofed to enable it to be returned to its prime use quickly in the aftermath of the flood

• No flooding elsewhere

Responsibility for satisfying the above criteria primarily will be the developer”.

 

Flood Risk

As part of the application process the applicant prepared and submitted a Flood Consequence Assessment (FCA). Upon receipt, Natural Resources Wales (NRW) were consulted. A copy of the NRW consultation response has been included as

APPENDIX 3 and in reaching a decision, Committee will need to have specific regard to its content.

The response states:

“As you are aware, the planning application proposes highly vulnerable development (Health Centre). Our Flood Risk Map, which is updated on a quarterly basis, confirms the site to be partially within Zone C1 of the Development Advice Map (DAM) contained in TAN15 and the 1% (1 in 100 year) and 0.1% (1 in 1000 year) annual probability fluvial flood outlines of the Afon Cynon. Our records also show the site previously flooded during the December 1979 flood event.

Section 6 of TAN15 requires your Authority to determine whether the development at this location is justified. Therefore, we refer you to the tests set out in section 6.2 of

TAN15. If the LPA consider the proposal meets the tests set out in criteria (i) to (iii), then the final test (iv) is for the Applicant to demonstrate, through the submission of an FCA, that the potential consequences of flooding can be managed to an acceptable level.

In our letter to your Authority, dated 07 June 2019, we required three matters to be addressed. The applicant has now submitted an FCA addendum, produced by CAPITA, dated June 2019, in response to our concerns. As such, we provide further advice in relation to the three concerns that we raised, below.

1. The development, including the staff car park, should be flood free during the predicted 1% plus an allowance for climate change flood event.

As you are aware, the original FCA showed that the staff car park is predicted to flood to a depth of 540mm, with a velocity of floodwaters of up to 1.8m/s. This is not in line with section A1.14 of TAN15. We have reviewed the addendum and we note that this risk has not changed. We understand that levels within the car park have been lowered to provide compensation for the raised area (the building). However, to be acceptable, the car park should be flood free during the predicted 1% plus an allowance for climate change flood event. We therefore maintain our concerns in relation to this matter.

2. There should be no increase in flood risk elsewhere.

As a result of the proposed flood mitigation, there is an increase in flood depth ranging between 30mm and 110mm in the Henry Street car park. This is not in line with the guidance set out in TAN15. We agree that the modelling predicts some betterment to the public highway (B4275) downstream of the site, as a result of this development, however this should not be used to offset any increases in flood risk to third party land outside the boundary of the site. TAN15 is clear that there should be no increase in flood risk elsewhere as a result of the development. We therefore maintain our concerns in relation to this matter.

 

3. Clarification regarding the retaining wall at the bottom of Henry Street car park as shown in drawing reference 18053-101 E.

 

From the information provided in the FCA addendum, it appears that the purpose of this retaining wall is to facilitate land raising behind it and it is not acting as a flood defence. This addresses our concerns and we therefore have no further comments to make on this matter. In consideration of the above, we confirm that our concerns relating to the flood risk to the staff car park and impact on flood risk elsewhere remain. If no further information is submitted, or a revised FCA fails to demonstrate that the consequences of flooding can be acceptably managed over the lifetime of the development, then we object to this application.” NRW go on to state: “As it is for your Authority to determine whether the risks and consequences of flooding can be managed in accordance with TAN15, we recommend you consider consulting other professional advisors on matters such as emergency plans, procedures and measures to address structural damage that may result from flooding.” In respect of this proposal, Members are advised that in reaching a decision Committee need to (a) acknowledge that the development does not comply with TAN15, (b) accept that there are risks in approving the development and (c) be satisfied that these risks are acceptable taking into account all other material planning considerations. That said, Committee is advised that the development does not comply with TAN15 insofar as the staff car park will flood to a depth of 540 millimetres with a velocity of floodwaters up to 1.8 metres per second and the development results in detriment (increased flooding) to third party land. The rest of the development appears to be broadly compliant with TAN15. Committee is advised that it is noteworthy that the development of a car park, per se, in a C1 Flood Zone is classed as “less vulnerable” development and it could be open to the applicant to withdraw this element of the current application and resubmit separately. While the flooding consequence, in combination, would be identical the broader considerations of the respective applications would seem to be more straightforward. In addition, the development also results in detriment to “third party” land. In this case the land in question belongs to the Council (the Henry Street car park). Following receipt of the NRW response, discussions were held with the applicant’s consultants with a view to understanding any risks the development will have so that Committee can fully understand the risk involved and deliberate over whether that risk is acceptable.*

 

*In setting out the figures, and to give Members a “frame of reference” the height of a “normal” door is 2 metres (6ft 6in).

 

Committee is advised that the Henry Street car park (adjoining the development) currently floods (even if the development did not proceed). In a 1-30 year flood event levels will reach 2.3 metres (7ft 7in). As a result of the development this will increase to 2.33 metres (7ft 8in) – an increase of 0.03 metres (1 inch). In a 1-100 year event the figures are 2.6m (8ft 6in) to 2.66m (8ft 9in) – an increase of 0.06 metres / 3 inches. In a 1-100 year (with climate change) event the figures are 2.7m (8ft 11in) to 2.705m (9ft) – an increase of 0.05 metres / 2 inches and in a 1-1000 year event the figure are 3m (9ft 10in) to 3.10m (10ft 2in) – an increase of 0.11 metres / 4 inches. Therefore the increases as a result of this development range from 0.03m (1 inch) to 0.11m (4in)*. *Committee is advised that the imperial figures (inches) have been “rounded” for convenience When considering developments that have flooding consequences it is important that those areas “downstream” are taken into account so that any problems are not just diverted elsewhere. As part of the FCA the developer considered the impact on the B4275 towards Our Lady of Lourdes School and The Bailey Public House (approximately 100 metres “downstream” of the roundabout). It was found that in a 1- 30 year event there would be no additional flooding. In a 1-100 year event this would actually decrease (reduce flooding) by 0.31m (1ft). In a 1-100 (plus climate change) event it would decrease flooding by 0.21m (8 inches) and would again decrease flooding by 0.07m (3in) in a 1-1000 year event. Should Committee decide to approve the application (and it is subsequently constructed) the application site will flood in in a 1-100 year event however the flooding is contained to the staff car park at the northern end of the site. The building itself will be raised out of the flood plain. The application site will also flood in the 1-1000 year event however the building itself has been designed to withstand this (unlikely) event. In terms of how flooding will occur, Committee is advised that modelling shows the initial breach occurs around the B4275 bridge on the south bank and then travels down towards the town to the lowest points in the Henry Street car park. From the initial breach to the car park, modelling indicates that this will take between 40-45 minutes. In the event of a significant flood, it will take over 16 hours to start to disperse with areas along Miskin Road (leading towards Miskin) being the first to clear. Henry Street car park will take longer and may require clearing and cleaning up prior to allowing vehicles to pass. Access to the health facility can be maintained along Miskin Road via Darran Street if required, except in a 1-1000 year event. Committee is advised that both Cynon Vale and Rhos House are also currently within the flood zone. The Health Board have advised that they both have business continuity plans that cater for flood events. Services can be delivered at YCC Hospital in the period where a flood event causes issues with access to the new building.

 

During a 1-100 year event, Henry Street will be under 2.66 metres of water so will be unpassable for any vehicles and, as it is part of the “one-way” system, the only access from the north will be via Pryce Street, across Duffryn Street and down Darran Road. From the south, much of Miskin Road will remain largely unaffected in a 1–100 and a 1-100 year plus climate change event so access can be maintained (although not in a 1-1000 year event). In addition, the Mountain Ash Cross Valley Link will provide alternative access north to south. The applicant has prepared a “Flood Emergency Plan” to inform the occupants of the building on what measures they need to take in the event of a flood. These measures range from relocating cars, cancellation of appointments, relocation of services and a full evacuation protocol via Miskin Road and Darran Road. While not strictly being a principal reason for approving this application, Committee is advised that the current surgery at Rhos House is susceptible to flooding and the building will flood in a 1-100 year event. The Cynon Vale Surgery on Cardiff Road is also in the 1-100 year flood zone and is also susceptible to flooding and probably to a greater extent than the proposed building due to the “temporary” nature of the construction. It is therefore considered that the proposal improves access to health facilities in the area in a flood event. Committee is advised that approving any development that is contrary to TAN15 should never be taken lightly, however desirable the proposed development may be. That said, it would seem that the principal risk would be only to a staff car park and the remainder of the development has been designed to be as robust as possible in the event of a catastrophic 1-1000 year event. The amount of additional flooding at or near the site seems limited as the development actually decreases the amount of flooding / the impacts downstream. In light of the above it is considered that the risks associated with this development are minimal and have been mitigated as far as possible. The Health Board have a clear plan in respect of maintaining services in the event of a flood and NRWs “early warning” system should provide sufficient time to prepare for such an event so that any risk to life and limb is minimised. While acknowledging NRWs “significant concerns” in respect of the development’s performance against TAN15 it is considered that it is in accordance with Policy AW2 of the Rhondda Cynon Taf Local Development Plan and that the risks associated with the development are both limited and acceptable.

 

Below Letter from Natural Resources Wales

 

Rhondda Cynon Taf CBC

Sardis House

Sardis Road Pontypridd

CF37 1DU

FAO: Chris Jones 07 June 2019

 

Proposed two-storey primary care health centre, with associated car parking, bin store and bicycle store at LAND AT HENRY STREET, MOUNTAIN ASH

Thank you for referring us to the application above, which we received on 20 May 2019.

We have significant concerns with the proposed development as submitted. We recommend that you should only grant planning permission if the scheme can meet the following requirement and you attach the conditions listed below. Otherwise, we would object to this planning application.

Requirement: Flood risk - The application should demonstrate that the risks and consequences of flooding can be managed to an acceptable level in accordance with

TAN15.

Conditions 1-6: Land contamination.

Further information is given below.

Flood Risk

As you are aware, the planning application proposes highly vulnerable development (Health

Centre). Our Flood Risk Map, which is updated on a quarterly basis, confirms the site to be partially within Zone C1 of the Development Advice Map (DAM) contained in TAN15 and the

1% (1 in 100 year) and 0.1% (1 in 1000 year) annual probability fluvial flood outlines of the

Afon Cynon. Our records also show the site previously flooded during the December 1979 flood event.

Section 6 of TAN15 requires your Authority to determine whether the development at this location is justified. Therefore, we refer you to the tests set out in section 6.2 of TAN15. If

Ein cyf/Our ref: CAS-87678-Q4X9

Eich cyf/Your ref: 19/0526/10

Rivers House

St Mellons Business Park

Fortran Road

Cardiff

CF3 0EY

Ebost/Email:

southeastplanning@cyfoethnaturiolcymru.gov.uk

Ffôn/Phone: 03000 653 055

www.naturalresourceswales.gov.uk

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(iv) is for the Applicant to demonstrate, through the submission of an FCA, that the potential consequences of flooding can be managed to an acceptable level.

In our Pre-application Consultation letter, dated 05 April 2019, we advised that a FCA should be submitted in support of the planning application. We have also provided discretionary pre-application advice to the applicant on a strategic FCA for the wider Mountain Ash area. We have reviewed the FCA undertaken by Capita, dated May 2019.

Our advice to you is that the FCA fails to demonstrate that the risks and consequences of flooding can be managed to an acceptable level for the reasons explained below.

We understand that the FCA has used a 1D-2D Estry – Tuflow hydraulic model to assess the potential impact of fluvial flooding at this site. Please note, we have not reviewed the model and have taken the FCA outcomes and conclusions at face value on this occasion.

We consider that the model that has been used is based on the best available information.

The FCA has considered the following blockage / breach scenarios and their impact at the site:

Blockage Scenario 1: Simulating the defended 1% +climate change flood event with a blockage proportion of 25% applied to the footbridge at NGR 305166.6, 198738.9. (Given

the type of bridge and location we agree that 25% is an appropriate value.)

Blockage Scenario 2: Simulating the defended 1% + climate change event, but with a blockage proportion of 25% applied to the road bridge at NGR 304731.5,

199224.9. (Given the type of bridge and location we agree that 25% is an appropriate value.)

Breach Scenario 1: Simulating the defended 1% + climate change event but with a breach of 40m applied to the defences on the right bank downstream of the B4275. (40m is an appropriate length for length for an earth embankment of this type.)

We understand that the building will have a finished floor level (FFL) of 107.30m AOD and this was considered in the modelling. We understand that this level is based on the predicted 1% plus an allowance for climate change baseline flood level of 107.20m AOD with 100mm of freeboard. In order to accommodate the design floor level, a cut and fill exercise will be undertaken, to raise levels beneath the building and levels will be lowered within the car park to provide compensation for the raised area.

During the predicted 1% plus an allowance for climate change flood event, the building and visitor car parks are predicted to be flood free. However, the staff car park car park is predicted to flood to a depth of 540mm, with a velocity of up to 1.8m/s. The rate of rise of floodwater is approximately 0.37m/hr where depths are greatest on the site. The model predicts it will take approximately 2 hours from the site first being inundated for the maximum water levels to be reached. This is not in line with TAN15, which sets out that the development should be flood free during this event.

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The FCA has assessed that there is a risk of blockage and breach at this location. The building is predicted to be flood free during these scenarios, however the staff car park is predicted to flood in all scenarios, this is set out below;

Blockage scenarios 1 & 2 - flood depths ranging from 0 and 800mm with a velocity of up to

1.5m/s.

Breach scenario- flood depth ranging from 0 and 400mm with a velocity of up to 1.2m/s.

During the predicted 0.1% event, the entire site is predicted to flood. This includes the building, both car parks and the Miskin road entrance. The building is predicted to flood to

a depth of 270mm during this event with velocities of up to 2.1m/s. This is not in line with

TAN15. Maximum velocity of flood waters should not exceed 0.15m/s. The staff car park is predicted to flood to a depth of 1130mm with velocities of up to 2.1m/s. The flood depths and velocities are not in line with TAN15, which states flood depths should not exceed 600mm and velocities should not exceed 0.3m/s. In addition, the rate of rise of floodwater is approximately 0.37m/hr where depths are greatest on the site. TAN15 sets

out that this should not exceed 0.1m/hr. The model also predicts it will take approximately

2 hours from the site first being inundated for the maximum water levels to be reached.

TAN15 sets out that this should not be any faster than 4 hours.

It is unlikely that there will be access to Henry street for events greater than the predicted

2% flood event as it is predicted to flood during these flood events. Therefore, there is no

safe access / egress for the staff car parking area during these predicted flood events.

TAN15 is clear that access /egress routes should be shown to be operational under all conditions.

TAN15 sets out that there should be no increase in flood risk elsewhere as a result of the development. The FCA has indicated that as a result of the proposed flood mitigation, there is an increase in flood depth ranging between 30mm and 110mm in the Henry Street car park. This is not in line with the guidance set out in TAN15.

Therefore, in consideration of the above, we require the following matters to be addressed;

1. The development, including the staff car park, should be flood free during the predicted 1% plus an allowance for climate change flood event.

2. There should be no increase in flood risk elsewhere.

We also require clarification regarding the retaining wall at the bottom of Henry Street car park as shown in drawing reference 18053-101 E. This appears to be raised to prevent flood water entering the development site. Is this being proposed to act as a flood defence structure? If so, has it been structurally designed for this purpose? Details should be provided. It is not known whether a modelled undefended scenario for the site with regards to this wall has been undertaken i.e. without the wall being raised to understand the consequences to the site.

 

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If no further information is submitted, or a revised FCA fails to demonstrate that the consequences of flooding can be acceptably managed over the lifetime of the development, then we object to this application.

Please inform us, in accordance with paragraph 11.7 of TAN15, if you are minded to grant permission for the application contrary to our advice.

As it is for your Authority to determine whether the risks and consequences of flooding can be managed in accordance with TAN15, we recommend you consider consulting other professional advisors on matters such as emergency plans, procedures and measures to address structural damage that may result from flooding. Please note, we do not normally comment on the adequacy of flood emergency response plans and procedures accompanying development proposals, as we do not carry out these roles during a flood.

Our involvement during a flood emergency would be limited to delivering flood warnings to occupants/users.

We provided the below advice in our Pre-application consultation letter, dated 05 April 2019, and we confirm it is still relevant;

Land Contamination

The proposed development site is near the Afon Cynon. The application form identifies the historic land use of the proposed development site as railway sidings. To avoid unacceptable risks to the environment, we would request the LPA attach the following conditions to any planning permission granted.

Condition 1: Universal condition for development on land affected by contamination

Prior to the [commencement of development] / [occupation of any part of the permitted development] approved by this planning permission (or such other date or stage in development as may be agreed in writing with the Local Planning Authority), the following components of a scheme to deal with the risks associated with contamination of the site shall each be submitted to and approved, in writing, by the Local Planning Authority:

 

1. A preliminary risk assessment which has identified:

• all previous uses

• potential contaminants associated with those uses

• a conceptual model of the site indicating sources, pathways and receptors

• potentially unacceptable risks arising from contamination at the site.

 

2. A site investigation scheme, based on (1) to provide information for a detailed assessment of the risk to all receptors that may be affected, including those off site.

 

3. The site investigation results and the detailed risk assessment (2) and, based on these, an options appraisal and remediation strategy giving full details of the remediation measures

required and how they are to be undertaken.

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4. A verification plan providing details of the data that will be collected in order to demonstrate that the works set out in (3) are complete and identifying any requirements for longer-term monitoring of pollutant linkages, maintenance and arrangements for contingency action.

Any changes to these components require the express consent of the Local Planning

Authority. The scheme shall be implemented as approved.

Reason

We consider the controlled waters at this site are environmentally sensitive and contamination is strongly suspected at the site due to the historic use of the site.

 

Condition 2: Verification report

Prior to [commencement of development]/ [occupation of any part of the permitted development] (delete as appropriate), a verification report demonstrating completion of the works set out in the approved remediation strategy and the effectiveness of the remediation shall be submitted to and approved, in writing, by the Local Planning Authority. The report shall include results of sampling and monitoring carried out in accordance with the approved verification plan to demonstrate that the site remediation criteria have been met. It shall also include any plan (a “long-term monitoring and maintenance plan”) for longer-term monitoring of pollutant linkages, maintenance and arrangements for contingency action, as identified in the verification plan, and for the reporting of this to the Local Planning Authority.

 

Reason

To demonstrate that the remediation criteria relating to controlled waters have been met, and (if necessary) to secure longer-term monitoring of groundwater quality. This will ensure that there are no longer remaining unacceptable risks to controlled waters following remediation of the site.

 

Condition 3: Long-term monitoring

Reports on monitoring, maintenance and any contingency action carried out in accordance with a long-term monitoring and maintenance plan shall be submitted to the Local Planning

Authority as set out in that plan. On completion of the monitoring programme a final report demonstrating that all long- term site remediation criteria have been met and documenting the decision to cease monitoring shall be submitted to and approved in writing by the Local

Planning Authority.

Reason

To ensure that longer term remediation criteria relating to controlled waters have been met.

This will ensure there are no longer remaining unacceptable risks to controlled waters following remediation of the site.

 

Condition 4: Unsuspected contamination

If, during development, contamination not previously identified is found to be present at the site then no further development (unless otherwise agreed in writing with the Local Planning

Authority) shall be carried out until the developer has submitted, and obtained written

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Reason

It is considered possible there may be unidentified areas of contamination at the site that could pose a risk to controlled waters if they are not remediated.

 

Condition 5: SuDS

No infiltration of surface water drainage into the ground is permitted other than with the express written consent of the Local Planning Authority, which may be given for those parts of the site where it has been demonstrated there is no resultant unacceptable risk to controlled waters. The development shall be carried out in accordance with the approval details.

Reason

There is an increased potential for pollution of controlled waters from inappropriately located infiltration systems such as soakaways, unsealed porous pavement systems or infiltration basins. Refer to: the SuDS Manual (CIRIA C753, 2015), the Susdrain website

(http://www.susdrain.org/ ) and draft National Standards for SuDS (Defra, 2011) for further information.

 

Condition 6: Piling

Piling or any other foundation designs using penetrative methods shall not be permitted other than with the express written consent of the Local Planning Authority, which may be given for those parts of the site where it has been demonstrated there is no resultant unacceptable risk to groundwater

Reason

There is an increased potential for pollution of controlled waters from inappropriate methods of piling. Refer to : Environment Agency Document ‘Piling and Penetrative Ground

Improvement Methods on Land Affected by Contamination: Guidance on Pollution

Prevention’ and Environment Agency Document ‘Piling in layered ground: risks to groundwater and archaeology’

 

Further Advice to applicant

We strongly recommend developers should:

• Follow the risk management framework provided in CLR11, Model Procedures for the

Management of Land Contamination, when dealing with land affected by contamination;

• Refer to WLGA document ‘Development of Land Affected by Contamination: A Guide for Developers’ (2017) for the type of information that we require to assess risks to controlled waters from the site. The Local Authority can advise on risk to other receptors, such as human health;

• Refer to the groundwater protection pages on Gov.UK

https://www.gov.uk/government/collections/groundwater-protection;

• Refer to British Standard for the Investigation of Potentially Contaminated Sites. Code of Practice (BS10175:2011).

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Other matters

Our comments above only relate specifically to matters included on our checklist,

Development Planning Advisory Service: Consultation Topics (September 2018), which is published on our website. We have not considered potential effects on other matters and do not rule out the potential for the proposed development to affect other interests, including environmental interests of local importance. We advise the applicant that, in addition to planning permission, it is their responsibility to ensure they secure all other permits/consents relevant to their development. Please refer to our website for further details.

If you have any queries on the above please do not hesitate to contact us.

Yours faithfully

Helen Griffiths

Development Planning Advisor

Natural Resources Wales

 

Proud to be leading the way to a better future for Wales by managing the environment and natural resources sustainably.

 

Correspondence in Welsh is welcomed, and we will respond in Welsh without it leading to a delay.

 

Another letter from Natural Resources Wales

 

Rhondda Cynon Taf CBC

Sardis House

Sardis Road

Pontypridd

CF37 1DU

FAO: Chris Jones

 

16 July 2019

 

Dear Sir/Madam

Proposed two-storey primary care health centre, with associated car parking, bin store and bicycle store at LAND AT HENRY STREET, MOUNTAIN ASH

Thank you for referring us to the additional information submitted in support of the application above, which we received on 27 June 2019.

We continue to have significant concerns with the proposed development as submitted.

We recommend that you should only grant planning permission if the scheme can meet the following requirement and you attach the conditions listed below. Otherwise, we would object to this planning application.

Requirement: Flood risk - The application should demonstrate that the risks and consequences of flooding can be managed to an acceptable level in accordance with

TAN15.

Conditions 1-6: Land contamination.

Further information is given below.

Flood Risk

As you are aware, the planning application proposes highly vulnerable development (Health

Centre). Our Flood Risk Map, which is updated on a quarterly basis, confirms the site to be

partially within Zone C1 of the Development Advice Map (DAM) contained in TAN15 and the

1% (1 in 100 year) and 0.1% (1 in 1000 year) annual probability fluvial flood outlines of the

Afon Cynon. Our records also show the site previously flooded during the December 1979

flood event.

Ein cyf/Our ref: CAS-92248-S5G5

Eich cyf/Your ref: 19/0526/10

Rivers House

St Mellons Business Park

Fortran Road

Cardiff

CF3 0EY

Ebost/Email:

southeastplanning@cyfoethnaturiolcymru.gov.uk

Ffôn/Phone: 03000 653 055

www.naturalresourceswales.gov.uk

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Section 6 of TAN15 requires your Authority to determine whether the development at this location is justified. Therefore, we refer you to the tests set out in section 6.2 of TAN15. If the LPA consider the proposal meets the tests set out in criteria (i) to (iii), then the final test

(iv) is for the Applicant to demonstrate, through the submission of an FCA, that the potential consequences of flooding can be managed to an acceptable level.

In our letter to your Authority, dated 07 June 2019, we required three matters to be addressed. The applicant has now submitted an FCA addendum, produced by CAPITA, dated June 2019, in response to our concerns. As such, we provide further advice in relation to the three concerns that we raised, below.

 

1. The development, including the staff car park, should be flood free during the predicted 1% plus an allowance for climate change flood event.

As you are aware, the original FCA showed that the staff car park is predicted to flood to a depth of 540mm, with a velocity of floodwaters of up to 1.8m/s. This is not in line with section A1.14 of TAN15. We have reviewed the addendum and we note that this risk has not changed. We understand that levels within the car park have been lowered to provide compensation for the raised area (the building). However, to be acceptable, the car park should be flood free during the predicted 1% plus an allowance for climate change flood event. We therefore maintain our concerns in relation to this matter.

 

2. There should be no increase in flood risk elsewhere.

As a result of the proposed flood mitigation, there is an increase in flood depth ranging between 30mm and 110mm in the Henry Street car park. This is not in line with the guidance set out in TAN15. We agree that the modelling predicts some betterment to the public highway (B4275) downstream of the site, as a result of this development, however this should not be used to offset any increases in flood risk to third party land outside the boundary of the site. TAN15 is clear that there should be no increase in flood risk elsewhere as a result of the development. We therefore maintain our concerns in relation to this matter.

 

3. Clarification regarding the retaining wall at the bottom of Henry Street car park as shown in drawing reference 18053-101 E.

From the information provided in the FCA addendum, it appears that the purpose of this retaining wall is to facilitate land raising behind it and it is not acting as a flood defence.

This addresses our concerns and we therefore have no further comments to make on this matter.

In consideration of the above, we confirm that our concerns relating to the flood risk to the staff car park and impact on flood risk elsewhere remain.

If no further information is submitted, or a revised FCA fails to demonstrate that the consequences of flooding can be acceptably managed over the lifetime of the development, then we object to this application.

 

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Please inform us, in accordance with paragraph 11.7 of TAN15, if you are minded to grant permission for the application contrary to our advice.

As it is for your Authority to determine whether the risks and consequences of flooding can be managed in accordance with TAN15, we recommend you consider consulting other professional advisors on matters such as emergency plans, procedures and measures to address structural damage that may result from flooding. Please note, we do not normally comment on the adequacy of flood emergency response plans and procedures accompanying development proposals, as we do not carry out these roles during a flood.

Our involvement during a flood emergency would be limited to delivering flood warnings to occupants/users.

We provided the below advice in our previous response letter, dated 07 June 2019; we confirm it is still relevant and we include it here for completeness;

 

Land Contamination

The proposed development site is near the Afon Cynon. The application form identifies the historic land use of the proposed development site as railway sidings. To avoid unacceptable risks to the environment, we would request the LPA attach the following conditions to any planning permission granted.

 

Condition 1: Universal condition for development on land affected by contamination

Prior to the [commencement of development] / [occupation of any part of the permitted development] approved by this planning permission (or such other date or stage in development as may be agreed in writing with the Local Planning Authority), the following components of a scheme to deal with the risks associated with contamination of the site

shall each be submitted to and approved, in writing, by the Local Planning Authority:

 

1. A preliminary risk assessment which has identified:

• all previous uses

• potential contaminants associated with those uses

• a conceptual model of the site indicating sources, pathways and receptors

• potentially unacceptable risks arising from contamination at the site.

 

2. A site investigation scheme, based on (1) to provide information for a detailed assessment of the risk to all receptors that may be affected, including those off site.

 

3. The site investigation results and the detailed risk assessment (2) and, based on these, an options appraisal and remediation strategy giving full details of the remediation measures required and how they are to be undertaken.

 

4. A verification plan providing details of the data that will be collected in order to demonstrate that the works set out in (3) are complete and identifying any requirements for longer-term monitoring of pollutant linkages, maintenance and arrangements for contingency action.

 

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Any changes to these components require the express consent of the Local Planning

Authority. The scheme shall be implemented as approved.

Reason

We consider the controlled waters at this site are environmentally sensitive and contamination is strongly suspected at the site due to the historic use of the site.

 

Condition 2: Verification report

Prior to [commencement of development]/ [occupation of any part of the permitted development] (delete as appropriate), a verification report demonstrating completion of the works set out in the approved remediation strategy and the effectiveness of the remediation shall be submitted to and approved, in writing, by the Local Planning Authority.

The report shall include results of sampling and monitoring carried out in accordance with the approved verification plan to demonstrate that the site remediation criteria have been met. It shall also include any plan (a “long-term monitoring and maintenance plan”) for longer-term monitoring of pollutant linkages, maintenance and arrangements for contingency action, as identified in the verification plan, and for the reporting of this to the Local Planning Authority.

 

Reason

To demonstrate that the remediation criteria relating to controlled waters have been met, and (if necessary) to secure longer-term monitoring of groundwater quality. This will ensure that there are no longer remaining unacceptable risks to controlled waters following remediation of the site.

 

Condition 3: Long-term monitoring

Reports on monitoring, maintenance and any contingency action carried out in accordance with a long-term monitoring and maintenance plan shall be submitted to the Local Planning

Authority as set out in that plan. On completion of the monitoring programme a final report demonstrating that all long- term site remediation criteria have been met and documenting the decision to cease monitoring shall be submitted to and approved in writing by the Local

Planning Authority.

 

Reason

To ensure that longer term remediation criteria relating to controlled waters have been met. This will ensure there are no longer remaining unacceptable risks to controlled waters following remediation of the site.

 

Condition 4: Unsuspected contamination

If, during development, contamination not previously identified is found to be present at the site then no further development (unless otherwise agreed in writing with the Local Planning

Authority) shall be carried out until the developer has submitted, and obtained written approval from the Local Planning Authority for, an amendment to the remediation strategy detailing how this unsuspected contamination shall be dealt with.

 

Reason

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It is considered possible there may be unidentified areas of contamination at the site that could pose a risk to controlled waters if they are not remediated.

Condition 5: SuDS

No infiltration of surface water drainage into the ground is permitted other than with the express written consent of the Local Planning Authority, which may be given for those parts of the site where it has been demonstrated there is no resultant unacceptable risk to controlled waters. The development shall be carried out in accordance with the approval details.

 

Reason

There is an increased potential for pollution of controlled waters from inappropriately located infiltration systems such as soakaways, unsealed porous pavement systems or infiltration basins. Refer to: the SuDS Manual (CIRIA C753, 2015), the Susdrain website

(http://www.susdrain.org/) and draft National Standards for SuDS (Defra, 2011) for further information.

 

Condition 6: Piling

Piling or any other foundation designs using penetrative methods shall not be permitted other than with the express written consent of the Local Planning Authority, which may be given for those parts of the site where it has been demonstrated there is no resultant unacceptable risk to groundwater

 

Reason

There is an increased potential for pollution of controlled waters from inappropriate methods of piling. Refer to: Environment Agency Document ‘Piling and Penetrative Ground

Improvement Methods on Land Affected by Contamination: Guidance on Pollution

Prevention’ and Environment Agency Document ‘Piling in layered ground: risks to groundwater and archaeology’

Further Advice to applicant

We strongly recommend developers should:

• Follow the risk management framework provided in CLR11, Model Procedures for the Management of Land Contamination, when dealing with land affected by contamination;

• Refer to WLGA document ‘Development of Land Affected by Contamination: A

Guide for Developers’ (2017) for the type of information that we require to assess risks to controlled waters from the site. The Local Authority can advise

on risk to other receptors, such as human health;

• Refer to the groundwater protection pages on Gov.UK

https://www.gov.uk/government/collections/groundwater-protection;

• Refer to British Standard for the Investigation of Potentially Contaminated Sites.

Code of Practice (BS10175:2011).

 

Other matters

Our comments above only relate specifically to matters included on our checklist,

Development Planning Advisory Service: Consultation Topics (September 2018), which is

www.naturalresourceswales.gov.uk

www.cyfoethnaturiolcymru.gov.uk Page 6 of 6 published on our website. We have not considered potential effects on other matters and do not rule out the potential for the proposed development to affect other interests, including environmental interests of local importance. We advise the applicant that, in addition to planning permission, it is their responsibility to ensure they secure all other permits/consents relevant to their development. Please refer to our website for further details.

 

If you have any queries on the above please do not hesitate to contact us.

Yn gywir / Yours faithfully

Helen Griffiths

New development should be directed away from zone C and towards suitable land in zone A, otherwise to zone B, where river or coastal flooding will be less of an issue. In zone C the tests outlined in sections 6 and 7 will be applied, recognising, however, that highly vulnerable development and Emergency Services in zone C2 should not be permitted. All other new development should only be permitted within zones C1 and C2 if determined by the planning authority to be justified in that location. Development, including transport infrastructure, will only be justified if it can be demonstrated that.

1 If a development proposal in zone C1, or in C2 if it is defined as being of low vulnerability, meets the test outlined in section 6, the justification will be in the knowledge that those developments will flood and will need to be planned accordingly. This section will apply in zone C, and those parts of zone B where flooding has been identified as a material consideration to allow for localised problems. 

Whether a development should proceed or not will depend upon whether the consequences of flooding of that development can be managed down to a level which is acceptable for the nature/type of development being proposed, including its effects on existing development. It would certainly not be sensible for people to live in areas subject to flooding (even in two storey buildings) where timely flood warnings cannot be provided and where safe access/egress cannot be achieved.