DRAFT STATEMENT OF COMMON GROUND
ON FLOOD RISK AND SURFACE WATER DRAINAGE
PINS Ref: APP/D0515/A/14/2210915/NWF
Fenland D.C. Ref F/YR13/0714/O
Appeal by Showfields Limited
Erection of up to 249 dwellings with associated infrastructure,
vehicular and pedestrian access, public open space and associated
flood mitigation works.
Land North of Whittlesey, East of East Delph, Whittlesey,
Cambridgeshire.
Introduction
1.
This Statement of Common Ground (SCG) relates to an appeal under section
78 of the Town and Country Planning Act 1990 (as amended) by Showfields Ltd and
considers matters relating to flood risk and surface water drainage. It provides the
areas of common ground between the Environment Agency, Showfields Limited,
Fenland District Council and North Level Internal Drainage Board.
2.
The Government's policy with regard to flood risk in the context of planning is
set out in the National Planning Policy Framework (NPPF), published on 27 March
2012. Paragraphs 100 to 104 of NPPF set out a sequential and risk based approach
to be adopted at all levels of planning. Paragraph 100 of NPPF covers the
requirement to consider flood risk from all sources and states that ‘inappropriate
development in areas at risk of flooding should be avoided by directing development
away from areas at highest risk, but where development is necessary, making it safe
without increasing flood risk elsewhere.’
3.
NPPF is supported by Planning Practice Guidance (NPPG) which is web
based guidance, last updated on 6 March 2014.
4.
Schedule 5 of the Town and Country Planning (Development Management
Procedure) (England) Order 2010 identifies the Environment Agency, as a consultee
under Article 16 on applications, other than minor development, which is to be
carried out on land –(ze) (i) in an areas within Flood Zone 2 or Flood Zone 3; or (ii) in
an area within Flood Zone 1 which has critical drainage problems and which has
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been notified for the purpose of this provision to the local planning authority by the
Environment Agency, and (zf) any development on land exceeding 1 hectare or
more.
5.
The Environment Agency's role as statutory consultee for flood risk is to
ensure that the technical requirements of NPPF in relation to coastal and fluvial flood
risk and surface water drainage are adequately considered in any planning
application. This is generally done through providing comments to the Local Planning
Authority (LPA) on the Flood Risk Assessment (FRA) submitted with the planning
application. A FRA must be provided for all sites within Flood Zones (FZ) 2 and 3 or
where the site area is greater than 1 ha. t. In this instance, the Environment Agency
is a party to the SOCG as statutory consultee to assist the Inspector on flood risk
matters at the Inquiry but is not a Rule 6 party as we have no objection to the
development subject to appropriate conditions being imposed It is not part of the
Environment Agency’s role to determine whether it is necessary to apply the
sequential test in accordance with paragraphs 100 to 104 of the NPPF,,or to
determine whether this test has been met. This role lies with the LPA in this case
Fenland District Council.
6.
The development site lies on the edge of the North Level Internal Drainage
District. The North Level Internal Drainage Board (IDB) is a drainage authority with
permissive powers to manage water levels within their district. They undertake works
to reduce flood risk to people and property and manage water levels to meet local
needs. They also provide advice and direction to local authorities and developers as
part of the Town and Country Planning process.
Site Location
7.
The site comprises a series of fields (or parts of fields) on the northern edge
of Whittlesey extending from East Delph (B1040), across to land to the north of
Moorhen Road. The site is bounded by existing development to the south and the
Whittlesey Washes to the north. The application site location plan shows the area
proposed for development edged in red.
Operation of Whittlesey Washes and Flood Levels
8.
The Whittlesey Washes Flood Storage Reservoir lies to the south of the River
Nene, east of Peterborough. It plays an important part in helping to reduce the risk of
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flooding in Peterborough and the surrounding area during combined high tides and
river flows. It is designated a reservoir under the Reservoir Act 1975.
9.
The reservoir is approximately 20km long and up to 1.4km wide in places. It
covers an area of approximately 1,450 hectares, reducing flood risk principally to
Peterborough. The Washes reduces risks to hundreds of properties, as well as
roads, railways and more than 8,000 hectares of farmland in the fenland area to the
south east of Peterborough.
10.
Flood water is stored on the Washes when high river levels cannot be
released downstream due to high tides when the tidal sluice gates at the Dog-in-aDoublet Sluice are closed. This is when the river is ‘tide-locked’. High flows from the
River Nene are diverted into Morton’s Leam through Stanground Sluice. When the
capacity of Moreton’s Leam is exceeded, water flows in to the Washes and is
contained by the South Barrier Bank and the Cradge Bank (separates the River
Nene from the Washes). The River Nene continues to flow and in extreme flood
events water from the River Nene also flows in to the Washes over the Cradge Bank
which forms the southern bank of the River Nene.
11.
As the tide recedes, water is released from the reservoir and back into the
River Nene from the eastern end of the Washes via the Rings End tidal sluice. The
equivalent of 14,000 Olympic‐sized pools of flood water can be temporarily stored on
the Washes. A diagram showing this can be found in Appendix A
12.
The lowest crest level of the South Barrier bank is 5.2m AOD. For a length
north of Whittlesey, the South Barrier Bank is not required as ground levels are
higher than in the surrounding fens. The Cradge bank, to the east of the Dog in a
Doublet is set at 4.3 m AOD. In extreme flooding scenarios where a prolonged series
of high tides coincides with very high river flows the River Nene and the Washes can
reach a level above the Cradge Bank. The Environment Agency have determined
that the maximum level of storage that can be achieved in the Washes before
flooding large portions of Whittlesey and the surrounding fens is 5m AOD. There are
however some lower lying residential areas to the north of Whittlesey which could
potentially flood before the maximum level of storage is reached. The Environment
Agency have used the 5.0m AOD level as defining the extent of the flood storage
and the Whittlesey Washes.
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13.
The rate at which the Washes fill and drain down depends on both the river
and tide conditions. The Washes may fill when high flows in the River Nene exceed
the discharge capacity of the Dog in a Doublet sluice even in low tide conditions or
where relatively normal river flows are restricted by reduced discharge through the
Dog in a Doublet sluice by high tides. The duration of high river flows or high tides
will also have an effect.
14.
There are a multitude of different hydrological scenarios such that defining the
probability associated with each (or cumulatively) would require highly complex
statistical analysis of joint probabilities. However, as discussed further in paragraph
18 the extent of the area designated as flood storage is considered to be functional
flood plain for planning purposes. Consequently joint probabilities have not been
considered further in relation to development planning.
15.
In summary, the designated functional floodplain is defined by the physical
maximum capacity of the Reservoir. It is recognised that the full extent will only be
used in extreme events although the frequency of this use may increase as a result
of the impacts of climate change.
16.
The flood levels contained within the FRA, provided by the Environment
Agency in 2011, are ‘in-channel’ levels based on a downstream tidal boundary set at
Mean High Water Springs (which is loosely an average of the high tides when the
tidal range is at its greatest). The model simulations from which these water levels
are derived provide a reasonable prediction of the water levels which will be
achieved during fluvial floods of the defined scenarios. The predictions are within
acceptable fluvial modelling tolerances but do not fully simulate all possible flooding
scenarios.
17.
The Environment Agency is currently carrying out improvements to the length
of the South Barrier Bank to maintain its structural integrity as required following the
latest reservoir safety inspection. These works involve strengthening the bank by
reshaping the slope of the bank and placing extra material at the base. This will not
affect the standard of protection offered by the Washes and has no implications on
the development site as the South Barrier Bank is not present at this location.
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Flood Map for Planning (Rivers and Sea)
18.
The Environment Agency has a suite of flood maps including the Flood Map
for Planning (Rivers and Sea). This shows the Flood Zones as set out in the National
Planning Policy Framework (NPPF).
19.
In this case the Nene Washes to the north of the appeal site is considered to
be Flood Zone 3b, Functional Floodplain. The level defining the boundary between
Flood Zone 3b and Flood Zone 1 is 5.0mAOD.
20.
The Flood Risk Assessment for the site, in Figure 4.1.1 shows the original
flood map for the site which the Environment Agency provided in 2011. At this time
the extent of storage of Whittlesey Washes and hence FZ3 was plotted on the 5
metre contour on the Ordnance Survey (OS) 1:10,000 scale map.
21.
In 2012 a flood map challenge was made to the Environment Agency based
on the site specific topographic survey. The challenge aimed to demonstrate that the
OS 5 metre contour was coarse and did not represent site specific levels in sufficient
detail.
22.
The Environment Agency compared the topographic survey to the their latest
survey undertaken using LIDAR (Light Detection and Ranging) which is a commonly
accepted technique for delivering highly accurate height data (ground levels). It was
found that both surveys gave the similar results and the flood map was changed
based on the LIDAR data. This is now shown on the published flood map for
planning (rivers and sea).
23.
The agreed extent of the 5.0mAOD contour is shown in the FRA as Figure
FRA02 revD.
Sequential test
24.
The NPPF sets out the requirement to apply a sequential test when
determining if development is appropriate in areas of flood risk. Paragraph 100 of
the NPPF advises that Local Plans should apply a sequential, risk-based approach
to the location of development, and to that extent, the LPA carries out a sequential
test. For individual applications, NPPG advises that it is for the applicant to present
sequential test information in an appropriate site specific FRA. NPPG contains
guidance on the level of detail in the CHECKLIST(paragraph 068 Reference ID: 7068-20140306). The NPPG, paragraph 034, Reference ID: 7-034-2013-0306 states
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that the developer should justify with evidence to the LPA what area of search has
been used when making the application. The role of the LPA is to consider whether a
sequential and exception test is required and whether this has been carried out
satisfactorily.
25.
The Environment Agency’s position of non-objection on the technical
accuracy of the flood risk assessment does not prejudice the LPA’s requirement for
and assessment of any sequential test. NPPF Paragraphs 102 and 103 set out that
the sequential test applies to the flood zone designation before the exception test is
applied.
26.
The Sequential test covers all forms of flooding as set out in Local Plan policy
LP14 and in various references in NPPG.
27.
The Environment Agency informs the exception test process by advising on
the accuracy of the flood risk assessment on safety issues, mitigating and managing
risks to others.
28.
The outcome of the sequential test is not agreed and is a subject of this
appeal.Environment Agency agrees with the FRA, and accordingly does not advises
the LPA that the development will not increase flood risk elsewhere. poses safety
risks. In the case of this development, the LPA considers that the sequential test
should be applied. The appellant considers that the sequential test is of no practical
purpose as the entirety of the development will be in FZ1.
The Development proposal
29.
It is agreed that drawing FRA02 Revision D shows the site specific extent of
FZ3b and in line with the published flood map for planning (rivers and sea).
30.
In order to rationalise the development potential for the site, the FRA
proposes (section 4.11) reprofiling of the site with floodplain compensation on a level
for level, volume for volume basis. It is agreed that this would involve raising ground
levels in the north and west of the site out of FZ3b (functional flood plain)and
lowering ground levels on a central parcel of land to bring this compensatory land
into the Whittlesey Washes. -It is agreed that this technical solution which is
acceptable to the EA in both technical and practical terms, would ensure that postdevelopment, no built development would be located in FZ3 (that is lower than the 5
metre contour) and all built development would be entirely with FZ1. There with will
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be no volume of storage lost within the Whittlesey Washes and therefore the
development would not give rise to increased risk of flooding elsewhere.
The technical and practical feasibility of the flood compensation works has
been agreed with the Environment Agency. This agreement does not imply
that the proposal is acceptable in respect of planning policy or negate the
requirement for the sequential test.
Other Matters
31.
The Environment Agency has not considered the desirability of public open
space, highways or private curtilage flooding - FDC considers this to be their role, as
informed by relevant advisors. Whilst the EA advises that it is principally tasked with
avoiding significant risks of internal flooding, the EA can advise LPAs where flooding
of external space may remain a risk. The EA and FDC agree that it is for the LPA to
assess the acceptability of the impacts of flooding in relation to material
considerations such as private amenity space, public amenity space, utilities,
transport, access for disabled persons and landscaping.
Signed
Environment Agency.................................................
Fenland District Council.............................................
North Level Internal Drainage Board..........................
Showfields Limited......................................................
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