SEVERN & AVON VALLEY COMBINED FLOOD GROUP
Questions for Council from Severn & Avon Valley Flood Group
Q1. (NACRA Newtown)
In our report “Building on the Floodplain is Misguided (A Definitive Proof of Evidence)” we state that Tewkesbury Borough Council has permitted building on the floodplain. Does each Councillor believe that this is correct or do you believe the Director of Strategic Operations and his officer’s statement on many occasions that TBC has not built or given permission to build in the floodplain?
A1. Each Councillor will make his or her mind up about the evidence considered by the Overview & Scrutiny Committee. The Committee found no evidence that Tewkesbury Borough Council had permitted new residential development in the floodplain. Officers presented evidence at a workshop for Members to consider and those Councillors who sit on the Planning Committee are aware that the Council’s policy precludes residential development in the floodplain and this policy is strictly adhered to.
In addition, the Gloucestershire County Council Overview and Scrutiny Management Committee’s Planning and Flood Risk Task Group concluded this year that “Tewkesbury Borough Council have demonstrated that new developments have been built within Flood Zone 1, not Flood Zone 3a.”
Q2. (WCRA Wynyards Close)
Our report “Building on the Floodplain is Misguided (A Definitive Proof of Evidence)” states that the Environment Agency does not include PLUVIAL (rainfall) in their flood mapping. The Environment Agency state that their flood map is a starting point only and PLUVIAL (rainfall) and other sources of flooding should be included by the Local Planning Authority. Do you believe that this is a fundamental error both on the EA’s part and more crucially by the TBC’s LPA and why?
A2. The Council and EA carefully use the guidance contained in PPS25 and support the Practice Guide which expands the guidance on Surface Water Management. In the Flood Risk Assessments, which this Council as Local Planning Authority request, the EA and the consultants involved will consider all issues that may contribute to flood risk and the assessment will deal with this.
Q3. (Mill Avon)
The Regional Flood Risk Appraisal was done by the South West Regional Assembly in February 2007. It forms the basis for all the other flood risk assessments (SFRA levels 1 and 2 and the FRA’s). The TBC did not submit evidence for this appraisal. This area has one of the largest floodplains in the UK! Professor Cluckie believes this severely handicaps the SFRA (Strategic Flood Risk Assessment) level 1 and 2 to the detriment of the people of the Borough. Why did the TBC not submit evidence for this appraisal?
A3. The Regional Flood Risk Appraisal, carried out by consultants on behalf of the South West Regional Assembly, covered the SSTC (Strategically Significant Cities and Towns) area in Gloucestershire as described in the document. Tewkesbury Borough Council did provide information to the Environment Agency for input into this work. There is no evidence whatsoever that this has in any way handicapped the SFRA level 1 work which the Borough Council and EA have been closely involved in and there is therefore no detriment to the people of the Borough.
Q4. (Oldbury Residents)
The Severn and Avon Combined Flood Group report states that SUDS (Sustainable Urban Drainage Systems) is used as a panacea to solve flood problems when building in or near the floodplain. The report also states that the Tewkesbury area floodplain and the soils of Gloucestershire are predominantly impervious clays and that SUDS will not be effective in many parts of Gloucestershire. Why does TBC insist that SUDS is the catch all solution to the problem for building large developments in and near the floodplain in this area?
A4. Sustainable Urban Drainage Systems form a range of practical methods to dealing with drainage and run off from new development areas in terms of water quantity and quality. Particular care has to be taken at or near areas prone to flood risk. Soils analysis forms part of the assessment and any proposed site specific surface water disposal strategy will have to adapt to the local conditions. The guidance on SUDS contained in PPS 25 and the accompanying Practice Guide sets down the approach that has to be followed. Many of the systems contained beneath the SUDS umbrella have been used within the surface water management industry, and by TBC, for many years with a high level of success.
Q5. (T.T. North)
The Director of Strategic Operations has stated that water displacement is a theory and not supported by facts. We refer you to recommendation 19 of the report. Do the members of this council believe that water is displaced during flooding in this area to the detriment of the people of the Borough?
A5. The water displacement theory was not accepted by the Overview & Scrutiny Committee. Recommendation 19 of the Pitt Report suggests that Local Authorities should assess and if appropriate enhance their technical capabilities to deliver a wide range of responsibilities in relation to flood risk management. The Borough Council has appointed a Land Drainage Officer and commissioned (jointly with the County and other Districts) a Strategic Flood Risk Assessment. The Borough is advised by the EA who also do not accept the water displacement theory.
Q6. (Severn and Avon)
As a Local Authority TBC should, under the EU Water Framework Directive, be heavily involved in the establishment of Catchment Flood Management Plans this deals with all aspect of flooding and inputs to a SFRA. It sets the scene for strategic flood risk management within a catchment for many years. This should involve the participation of the public and also be publicly available. TBC should be collaborating with the EA on this. How developed are these plans and when will the public be able to scrutinise them?
A6. The Severn Catchment Flood Management Plan is being developed and the Borough Council and the local EA staff have been included in the production of the Draft. It is understood that the draft document was to be placed on the EA website in July 2008.
Q7. (Save the Countryside)
When a development is at all controversial the officers always advise that the TBC cannot afford to go to appeal because they will be sued. We would refer you to recommendation 19 of the Severn and Avon report. Do you as councillors believe that this is a genuine excuse for the passing of controversial applications?
A7. The statement is not quite correct. Officers do not advise Members in the terms set out. Where a proposed planning refusal reason cannot be substantiated Members will be advised about the possibility of a costs award at Appeal and Members have to weigh this advice in the balance before making a decision Members do not see it as an “excuse for the passing of controversial applications” as it is recognised that there must be substantive and robust reasons for refusal which will stand the test at appeal. The Members do on occasions take a risk to test important principles.
Q8. (MACA Mitton)
Councillors are aware of the two maps prepared by the Environment Agency, the Indicative Flood Plain Map (FLUVIAL), issued to TBC and used for planning applications, and the Hydrology Map of 2003 (which needs updating), not issued by the EA but issued to the Severn and Avon and reported in the report “Building on the Floodplain is Misguided (A Definitive Proof of Evidence)”. Based on the Hydrology of the July 2007 floods, which map is more accurate as a flood map and should be used for planning applications?
A8. The EA provides the Flood Plain Map but the Hydrology Map placed before the Overview & Scrutiny Committee by the Severn & Avon Valley Flood Group is not quite accurate and has not been formally issued by the Environment Agency. The Local Planning Authority consult the EA on relevant planning applications and request Flood Risk Assessments where there is some degree of risk in flood prone areas. The EA see the assessments and comment on them. The EA Flood Plain Map (attached) is a realistic and accurate guide to the broad extent of the 100 year functional flood (based on the 1947 event) and is used to indicate the area where the floodplain should be protected in accordance with the guidance in PPS 25. This is supplemented by Flood Risk Assessments where development proposals are submitted next to the floodplain or in areas prone to risk from flooding. The July 2007 floods were estimated to be a 250 year event.
Q9. (Northway)
In the case the TBC accepts a SUDS solution as a means of mitigating the effects of a major development, what financial guarantees are to be put in place to ensure that the long-term commitment of the TBC in terms of maintenance and operation of the SUDS scheme for the full life of the development are at no cost to the TBC?
A9. The Borough Council deals with the arrangements for long term maintenance through Section 106 Legal Agreements associated with major development proposals. These agreements contain commuted sums to cover the costs of such maintenance. The adoption of reed beds and balancing ponds normally occur after the development is completed so that the developer has to maintain them until they are handed over. This practice has been in place for many years.
Supplementary Questions from Council – 10.11.08
Supplementary Question 1:
The Wychavon District Council, which is the neighbouring Council to the North of this Borough, has intimated to us that they realise they have encroached into the floodplain and need to tighten up their planning policy. Professor Cluckie generally concurs with our report that the TBC have built in the floodplain. The Environment Agency (EA) has advised on many occasions that their flood map is a starting point only and it is up to the TBC to include (enhance if you like) the flood map with all other sources of flooding and yet you still insist on issuing the basic map from the EA to developers. There is an appeal tomorrow on one of the Bredon Road developments which the TBC said in their assessment was not in the floodplain, when we asked TBC for copies of the EA’s assessment you advised that they only commented on the one not in the appeal. Can you explain why this Council keeps insisting that you have not built in the floodplain, why you continue to pass developments in the floodplain and what is the documented evidence that you have not?
Answer
The Borough Council has not permitted any new residential development in the floodplain. The evidence is available and has been shown to you including a comparison of built development and floodplain maps / contour plans. The Environment Agency flood map is a starting point and each development proposed in areas next to floodplain or prone to flood risk has to be accompanied by a Flood Risk Assessment.
The Bredon Road appeal case was considered by the Council’s Planning Committee which was satisfied that the development was all above the 12.92 metre line identified by the Environment Agency as the extent of the July 2007 flood. However, it should be noted that the Council refused the proposed development for other reasons.
Where essential infrastructure development has been considered (such as part of the ERR for example) within the floodplain, measures have to be taken to demonstrate to the satisfaction of the Environment Agency that no increased flood risk is created elsewhere, including floodplain compensation measures if required, through cut and fill exercises. You will recall that you were shown areas where the land was lowered to compensate for that part of the ERR that passed through former floodplain.
Supplementary Question 2:
Professor Cluckie agrees with our report that the EA’s flood map is only a starting point and does not include PLUVIAL flooding. PLUVIAL flooding information is available from Severn Trent Water who use computer models such as “Info Works” for PLUVIAL flooding for their sewerage systems. Why does the TBC LPA not work in conjunction with Severn Trent and include this information in the flood maps they issue for guidance to developers?
Answer
The Council as Local Planning Authority works with the Environment Agency and Severn Trent Water using the Government guidance contained in PPS25. Peak rainfall is dealt with (table B.2 of PPS25) and allowances have to be incorporated in any assessment to take account of this. Annex B of PPS25 details what needs to be considered in connection with climate change and the apparent trend for wetter winters with a larger proportion of winter rainfall taking place in heavy rainfall days than was the case 50 years ago (paragraph B.1 PPS25). The Council benefits from the expertise of the Environment Agency and Severn Trent who are consulted on major developments.
As part of the sewerage system adoption process, Severn Trent Water assess the suitability of the design of a system using computerised hydraulic models. As you will know, part of that process is to select relevant soil indexes and rainfall hydrographs for the area concerned and the catchment within which the development lies. This incorporates the pluvial element of the conditions with which the sewerage system will have to cope.
Supplementary Question 3:
Incompetence? You say that you did submit evidence, the Severn and Avon Valley Combined Flood Group would like a copy, and accordingly it seems that the SWRA left your evidence out. Why did this Council not challenge the SWRA on the omission and insist that the RFRA include an appraisal of this information?
Answer
The Council has stated in its previous response to this question that it has liaised with the Environment Agency on all matters relating to flood risk and new development which included work on the North Gloucestershire and North West Cheltenham proposed urban extensions. The Regional Flood Risk Assessment covers the Gloucester and Cheltenham Sub-Region (paragraph 8.3) and the figures at 10 and 11 show the existing floodplain. You will also note that at Appendix E Market Towns, Tewkesbury/Ashchurch is identified as being within Flood Zone 3. The Council does not accept that there has been any omission. (A copy of the relevant extract of the SWRFRA is attached).
Supplementary Question 4:
Professor Cluckie and Simon Fox (MSc, BSc, MBCS, MIBC) agree that there is a small possibility that the storage methods employed in SUDS may work, but Hydrographs need to be calculated to show the performance, before and after, of a SUDS design. This should be the responsibility of developers. We refer you to recommendation 19 of the report and ask Why does the LPA not employ professional hydrologists and engineers to assess planning applications for major development?
Answer
The Council does not employ professional hydrologists but does have experienced engineers and planners. It also relies on the expertise provided by Severn Trent and the Environment Agency as referred to above. In dealing with any major development proposal in or close to an area prone to flood risk, there has to be a thorough flood risk assessment. The Longford planning application and subsequent appeal documents demonstrate how this works. Hydrologist’s expertise has to be brought to bear with the analysis of flood risk issues and also covers any possible solutions such as SUDS schemes. The Council has not, to date, considered it necessary to employ a hydrologist as this expertise is provided by the Environment Agency and Severn Trent.
Supplementary Question 5:
It is obvious that these compulsory methods did not work in July 2007 and that the LPA did not prove their calculations with basic hydrological tools such as hydrographs. In a soon to be published report on flooding by Dr Richard Furness of Tirley, the report states that building in the floodplain has caused changes in flow patterns further downstream and there is clear evidence that once river levels reach 11 metres the western side of the floodplain between Chaceley and Tirley now floods far more rapidly than a decade ago and takes longer to drain away. In the report “Building on the Floodplain is Misguided (A Definitive Proof of Evidence)” there is a chart for water displacement by built up development in the floodplain. This chart for water displacement is on the conservative side as calculations for uncertainty levels are not included. Professor Cluckie believes that uncertainty levels are a basic hydrological tool and crucial to determine flood mapping. Why does the LPA not include uncertainty levels on the flood maps issued to developers and do you believe that building on the floodplain has changed the dynamic flow patterns of the floodplain?
Answer
Historic development in the floodplain may have changed flow patterns (you will have heard of Cllr Phil Awford’s view on the impact of the Hempstead Tip area on flood flow and the floodplain for example). The Local Planning Authority works closely with the Environment Agency and Severn Trent who have hydrological expertise available to them.
The Borough Council has been working with Dr Richard Furness and provided information to assist his work. Discussions have also taken place about potential schemes to further mitigate the effects of flooding in Tirley. In addition, the Borough Council has been working with the Internal Drainage Board to facilitate improvements to the drainage systems in the floodplain to the west of the River Severn in the Tirley area.
It is not clear as to what you mean by “uncertainty levels”. It is not a term regularly used within the practioner’s arena but may be one used in academia. Tolerances are built into different elements of the process to account for uncertainties and the 20% plusage to the 100yr storm for climate change is a good example. All practioner’s will accept that hydraulic modelling is not a totally precise science but also that every storm is different. For this reason, tolerances will be built into most aspects of the process to allow for uncertainties.
Supplementary Question 6:
At the presentation given to the people at Longford Village Hall by the Strategic Director of Operations he stated that TBC employed a Hydrologist for advice on all large development applications dealt with by the LPA. Can you name this Hydrologist and provide contact details and also supply his/her advice on, for example, the Longford development?
Answer
The Longford Appeal assessment included dealing with the Borough Council’s putative refusal reason No. 6: The provision of on-site attenuation and treatment of surface water run-off. Technical evidence on the refusal reason was provided by Mr Dale, a Principal Engineering Hydrologist and Director of Capita Symonds, commissioned by the appellant’s. Professor Cluckie also contributed to the discussion on this issue. The extracts from the Inspector’s report which are attached show that Professor Cluckie agreed that the work undertaken by the appellant’s hydrologist was best practice. He also agreed that the proposal met the tests in PPS25.
S & A comment:
This question was not answered Mr Shaw stated that TBC employed a hydrologist for advice on all developments. We have now found out this is incorrect.
Supplementary Question 7:
Professor Cluckie believes that with the right kind of professional advice there are sufficient ways and means for rejecting applications due to the uniqueness of the floodplain and soil composition in Gloucestershire. David Stritch of Communities and Local Government states “Local Planning Authorities should not be at any disadvantage in relation to appellants, when appeal cases are involved”. Does TBC have the correct calibre of advice to be successful in planning and winning appeals?
Answer
The Local Planning Authority considers that it does have the right calibre of advice available to it through close working with the Environment Agency and Severn Trent in addition to in-house expertise. Where specialist advice is considered to be required, consultants are commissioned by the Borough Council. At Longford the appropriate scrutiny of the putative refusal reason No. 6 by the Inspector, demonstrates that this is the case. As explained at the Longford Public Meeting, the evidence placed before the Inspector was accepted by Professor Cluckie. The preliminary SUDS layout shows the different requirements dictated by the differing ground conditions – Yellow area not suitable for infiltration, orange area suitable. (See plan).
S & A comment;
Professor Cluckie agreed with the methodology (computer programme used) but the methodology can be manipulated he did not agree with their results.
Supplementary Question 8:
Professor Cluckie believes that the Hydrology Map of 2003 is more accurate but needs updating e.g. the Severn is occasionally affected by the tide in times of flood. He also believes that the report by the Severn and Avon should be adapted to become a working document for the LPA and others. Will this Council adopt its findings and adapt the report for its planning policy?
Answer
The Council has produced its Report on the Response to Flooding with recommendations. It has not recommended adopting the report of the Severn and Avon Group but it has accepted some of its views and they are reflected in the recommendations. The Council has written to the Environment Agency asking that it reviews and updates the floodplain maps covering the whole Borough including consideration of local knowledge and information.
Supplementary Question 9:
Does TBC have any experience of operating and maintaining a SUDS scheme and if the SUDS scheme does not prevent flooding downstream of a major development, then are the TBC responsible?
Answer
TBC has adopted several balancing ponds and systems (throughout the Borough) that mitigate and manage surface water. Sustainable Urban Drainage Systems are designed to ensure that the risk to flooding of homes is not increased by any proposal (paragraph 54 Inspector’s Report on Longford) and that there is no additional run-off from development sites. As the Inspector at Longford reported, “Indeed the SUDS would deliver a long-term reduction in flood risk to the general area”.
A SUDS Scheme may help to reduce the risk of downstream flooding but this is not strictly its main purpose so that the question regarding responsibility does not arise – there is no question of such responsibility being attributed in this way. In simple terms, this repeats an allegation made before, namely that the development of Wheatpieces made the flooding worse for residents elsewhere which is just not the case.
I would also refer you to the answer to your original Question 9 with regard to the SUDS principles.