station yard corwen road, coed-talon flood consequence assessment

Transcription

STATION YARD
CORWEN ROAD, COED-TALON
FLOOD CONSEQUENCE ASSESSMENT
For
SPA Davies and Sons,
Station Yard,
Corwen Road,
Coed-Talon,
Flintshire,
CH74TG.
November 2014
Station Yard, Coed-Talon, Flintshire
Flood Consequence Assessment
This page has been intentionally left blank
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Sta ti on Ya rd, Coed-Ta l on, Fl i nts hi re
Fl ood Cons equence As s es s ment
STATION YARD
FLOOD CONSEQUENCE ASSESSMENT
Document Tracking Sheet
Document Reference: FRA262-FCA
Revision:
2.0
Date of Issue:
11th November 2014
Report Status:
Final
Prepared by:
____________________________________
Kirsty Williams BSc (Hons)
Graduate Flood Risk Analyst
Checked by:
____________________________________
Mel Frimston BSc (Hons) CEng MIStructE
Managing Director
Authorised by:
____________________________________
Richard Nicholas BEng (Hons) MBA
Associate
Revision History:
Rev.:
Date:
2.0
11th November 2014
1.2
31st October 2014
1.1
16th October 2014
1.0
25th July 2014
FRA262 – FCA
Status:
Final
Draft
Draft
Draft
Prepared by:
KW
KW
KW/RDN
KW
Checked by:
RMF
RMF
RMF
RDN
Issued by:
RDN
RDN
KW
KW
~ iii ~
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EXECUTIVE SUMMARY
This Flood Consequence Assessment was commissioned on behalf of SPA Davies and Sons, referred
to hereafter as ‘the client’. This FCA has been prepared to support an outline planning application
for the construction of a residential development; complete with access road, external works,
footpaths, car parking, landscaping, boundary walls, fencing, external services and drainage on land
previously occupied by ‘Station Yard’ Coed-Talon.
The site is predominantly located within Flood Zone A, with the eastern boundary located within
Flood Zones B and C2. The residential nature of the proposals means the site is classified as ‘highly
vulnerable’; the proposals would be considered ‘acceptable’ within Flood Zone (A); providing all
surface water management requirements are conformed to. This nature of development would also
be considered appropriate within Flood Zone B providing appropriate mitigation measures were in
place to secure the development for its design life.
As the proposed site is currently brownfield, it can be considered that the residential proposals offer
betterment on the existing situation and would be considered appropriate providing the flood risk to
site can be effectively managed. It would therefore be recommended that an intra-sequential
approach to flood management be adopted and development be steered to areas at least risk.
The development site is understood to be partially located within Flood Zone B and C2; underlain by
a ‘Secondary A’ Aquifer, influenced little by overland run-off due to the topography and influenced
by surface water flooding in varying degrees of severity due to the existing land-use.
It is considered that the majority of site would remain flood free during the design period event
(Q100+CCA event), following the review of the hydraulic model; due to sufficient capacity within the
existing culverts onsite. The water surface elevation varies through site based on the location and
proximity to the watercourse, however no out of channel flooding is anticipated within site based on
the simulations.
The existing Byr Brook culvert upstream of site is considered to have insufficient capacity to cater
with the extreme events, some out of channel flows would be anticipated upstream of site, however
any water not able to enter the existing system would flow safely away from site, utilising the
existing drainage systems within the highway (Corwen Road) or converging along the highway, to
the south of site.
The proposed removal of the culverts onsite and implementation of open channels would have a
positive effect on the water surface elevation levels for the upstream watercourses, reducing the
upstream flood risk. The proposed open channel simulation did not show any significant changes to
the downstream water surface elevation along Byr Brook and therefore no increase in flood risk
would be anticipated.
Although the extent of the flood zone is within the channel of the watercourses for the 100year
return period event, mitigation measures are proposed in the form of Finished Floor Levels (FFL)
which are proposed a minimum of 600mm above the 1% AEP (1 in 100 year) event with an
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allowance for climate change. The proposed FFL will vary based on the location and proximity to the
watercourse; detailed design should account for this variation through site and set FFL’s to reflect
such.
Compensatory Flood Storage will not be required as no displacement of floodplain waters in
anticipated at this time.
Consultation with Natural Resources Wales identified one recorded historic flood event, in 2000,
associated with the tributary of ‘Byr Brook’ at the inlet of the upstream culvert within the site
boundaries. It is understood that the flooding occurred due to the presence of debris blocking the
inlet, fly-tipping upstream and the presence of services pipes crossing the watercourse. No other
historical flood incidents have been identified, following removal of debris and relocation of the
services pipes to beneath the brook.
The development would be considered as accessible for emergency access and egress during times
of extreme flooding provided the proposed access/egress road culvert has sufficient capacity and
the channel is transformed to its natural state where possible; the maximum acceptable inundation
depths along the route should not exceed 600mm in accordance with TAN15 which are to be
confirmed during detailed design.
The FCA has reviewed all sources of flood risk to both the proposed development and to the existing
adjacent development as a result of the proposals, including; fluvial, tidal, pluvial, groundwater,
sewers and flooding from artificial sources.
Based on the ground conditions identified by the BGS and NSRI Soilscapes Data, it can be considered
that that infiltration is not likely to provide a feasible surface water management solution, therefore
it is proposed that surface water run-off, discharge to the watercourse running through site. Surface
water run-off rates will be restricted to the pre-development rates of run off for various events, up
to and including the 100 year return period event.
Restricting the rate of surface water discharge can be achieved using a flow control device such as a
Hydrobrake® or similar approved product. Restricting the rate of surface water run-off complies with
the requirements of TAN15 and generate a storage requirement during the extreme rainfall events.
It is proposed that up to and including the 100 year return period event with an allowance for
climate change (30%) be catered for on-site to comply with guidance in TAN15.
It is proposed that the foul water flows generated by the development discharge into the combined
sewer system (150mm dia.) located along the A5104 (Corwen Road) New Brighton, with an exact
connection point to be confirmed following site investigations, during the detailed design stage.
This FCA is considered to be commensurate with the development proposals and in summary, the
development can be considered appropriate in accordance with TAN15 and the mandatory
requirements of the Code for Sustainable Homes.
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CONTENTS
Document Tracking Sheet ................................................................................................................. iii
EXECUTIVE SUMMARY ................................................................................................................. v
Figures & Tables ................................................................................................................................ ix
Specialist Software............................................................................................................................. x
Abbreviations & Acronyms ................................................................................................................ x
1.0
INTRODUCTION .............................................................................................................. 11
1.1
Planning Policy Wales Context............................................................................................ 11
1.2
Technical Advice Note 15 (TAN15) ..................................................................................... 11
1.3
Site Context......................................................................................................................... 11
1.4
Consultation........................................................................................................................ 12
2.0
EXISTING SITE SITUATION ............................................................................................... 13
2.1
Location .............................................................................................................................. 13
2.2
Existing and Historical Land Use ......................................................................................... 13
2.3
Topography ......................................................................................................................... 14
2.4
Access and Egress ............................................................................................................... 15
2.4
Justification for Development ............................................................................................ 15
3.0
DEVELOPMENT PROPOSALS ............................................................................................ 16
3.1
4.0
Nature of the Development................................................................................................ 16
TECHNICAL ADVICE NOTE 15 (TAN15) .............................................................................. 17
4.1
Flood Zone Classification .................................................................................................... 17
4.2
Category of Development ................................................................................................... 18
4.3
Justification ......................................................................................................................... 19
4.4
Acceptability Criteria .......................................................................................................... 20
5.0
SOURCES OF FLOOD RISK ................................................................................................ 21
5.1
Fluvial & Tidal Flood Risk .................................................................................................... 21
Fluvial Flooding ................................................................................................................. 21
Hydraulic Assessment ....................................................................................................... 22
Method ............................................................................................................................. 22
Results .............................................................................................................................. 24
5.2
Tidal Flooding...................................................................................................................... 28
5.3
Groundwater Flood Risk ..................................................................................................... 28
5.4
Artificial Sources of Risk...................................................................................................... 29
Reservoirs ......................................................................................................................... 29
Canals ............................................................................................................................... 30
5.5
Surface Water Flood Risk .................................................................................................... 30
Pluvial Flooding (Overland Run-off).................................................................................. 33
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Sewer Flooding ................................................................................................................. 33
5.6
Historical Events of Flooding .............................................................................................. 34
5.7
Flood Warning and Evacuation ........................................................................................... 35
Flood Warning .................................................................................................................. 35
Evacuation ........................................................................................................................ 35
Emergency Access and Egress .......................................................................................... 37
5.8
Flood Risk Mitigation Measures and Residual Risks ........................................................... 37
Mitigation Measures: Summary ....................................................................................... 38
Residual Risks: Summary .................................................................................................. 39
6.0
CLIMATE CHANGE ........................................................................................................... 40
7.0
SUSTAINABLE URBAN DRAINAGE SYSTEMS (SuDS)........................................................... 41
8.0
SURFACE WATER MANAGEMENT .................................................................................... 42
8.1
Pre-Development Surface Water Run-off........................................................................... 42
8.2
Post-Development Surface Water Run-off ......................................................................... 42
8.3
Methods of Surface Water Management ........................................................................... 43
8.4
Discharge via Infiltration ..................................................................................................... 43
8.5
Discharge via Watercourse ................................................................................................. 44
8.6
Discharge via Sewer ............................................................................................................ 45
9.0
FOUL WATER MANAGEMENT .......................................................................................... 46
10.0
SUMMARY AND CONCLUSIONS ....................................................................................... 47
11.0
RECOMMENDATIONS ..................................................................................................... 49
Bibliography & References ......................................................................................................... 50
Web-Based References .............................................................................................................. 50
APPENDIX A:
TAN15 COMPLIENCE LIST
APPENDIX B:
TECHNICAL REQUIREMENTS FOR TAN15
APPENDIX C:
LOCATION PLAN
APPENDIX D:
TOPOGRAPHIC SURVEY
APPENDIX E:
WELSH GOVERNMENT DEVELOPMENT ADVICE MAP (DAM)
APPENDIX F:
NRW/EA INFORMATION & CORRESPONDENCE
APPENDIX G:
WELSH WATER CORRESPONDENCE & RECORDS
APPENDIX H:
FLINTSHIRE COUNTY COUNCIL CORRESPONDENCE
APPENDIX I:
TAN15 EXTRACTS
APPENDIX J:
FEH CATCHMENT DATA & DESCRIPTORS
APPENDIX K:
SURFACE WATER RUN-OFF DATA & CALCULATIONS
APPENDIX L:
STORMWATER STORAGE ESTIMATES
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APPENDIX M:
IMPERMEABLE AREAS PLANS
APPENDIX N:
OVERLAND FLOOD ROUTING PLANS
APPENDIX O:
PFRA/LFRMP/CFMP EXTRACTS
APPENDIX P:
PHOTOGRAPHS
APPENDIX Q:
REFH FLOW eSTIMATES
APPENDIX R:
1D MODELLING OUTPUTS - EXISTING
APPENDIX S:
OVERLAND FLOOD FLOW PLAN
APPENDIX T:
1D MODELLING SENSIVITY TESTING OUTPUTS
APPENDIX U:
1D MODELLING BLOCKAGE SCENARIOS OUTPUTS
APPENDIX V:
1D MODELLING OUTPUTS - PROPOSED
APPENDIX W:
NOTES OF LIMITATION
Figures & Tables
Figure 1:
Aerial Photograph of site (Bing Maps, 2014) ................................................................... 13
Figure 2:
General Topography within Site Based On Observations. ............................................... 14
Figure 3:
Existing Site Situation Aerial Photograph (Bing Maps 2014)............................................ 16
Figure 4:
Development Advice Map Extract (Welsh Government, 2013) ....................................... 17
Table 1:
Development Category of Vulnerability (Source: TAN15: Section5)................................ 18
Figure 5:
Natural Resource Wales Fluvial Flood Zone Extract (NRW 2014) .................................... 21
Table 2:
ReFH Flow Estimates ........................................................................................................ 23
Figure 6:
Model Schematic HEC-RAS v4.1 - Existing (Betts Associates 2014) ................................. 23
Figure 7:
1D Hydraulic Model Profile Plot Output (Betts Associates 2014) .................................... 24
Figure 8:
1D Hydraulic Model Profile Plot Output (Betts Associates 2014) .................................... 25
Figure 9:
Overland Flood Flow Routing Plan extract (Betts Associates 2014) ................................ 26
Figure 10:
Model Schematic HEC-RAS v4.1 – Proposed (Betts Associates 2014) ............................. 28
Figure 11:
Groundwater Designation Map Extract (Environment Agency, 2014)............................. 29
Figure 12:
Reservoir Flood Map Extract (Environment Agency, 2014) ............................................. 30
Figure 13:
Surface Water Flood Map Extract (Environment Agency, 2014) ..................................... 31
Figure 14:
Flood Map for Surface Water 1 in 30 Map Extract (Natural Resources Wales 2014) ...... 32
Figure 15:
Flood Map for Surface Water 1 in 100 Map Extract (Natural Resources Wales 2014) .... 32
Figure 16:
Flood Map for Surface Water 1 in 1000 Map Extract (Natural Resources Wales 2014) .. 33
Figure 17:
Flood Event Outline Map Extract (Natural Resources Wales 2014) ................................. 34
Figure 18:
Flood Warning Map Extract (Environment Agency 2014) ................................................ 35
Figure 19:
Evacuation Route Plan (Betts-Associates 2014) ............................................................... 36
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Specialist Software
Flood Estimation Handbook FEH CD-ROM (v.3.0) – Determination of Catchment Descriptors
and depths of rainfall.
MicroDrainage: WinDES (v.2014.1) – Calculation of Greenfield run-off rates IH124/ICP-SUDS,
Greenfield run-off volumes, rates of rainfall and stormwater storage estimates.
Abbreviations & Acronyms
AEP
Annual Exceedance Probability
LPA
Local Planning Authority
BGL
Below Ground Level
mAOD
Metres Above Ordnance Datum
BGS
British Geological Survey
NGR
National Grid Reference
CC
Climate Change
NRW
National Resources Wales
CFMP
Catchment Flood Management Plan
NSRI
National Soil Resource Institute
DAM
Development Advice Map
OS
Ordnance Survey
EA
Environment Agency
PFRA
Preliminary Flood Risk Assessment
FEH
Flood Estimation Handbook
PPW
Planning Policy Wales
FCA
QSE
Quick Storage Estimate
FCC
Flintshire County Council
SFCA
Strategic Flood Consequence Assessment
FUDP
Flintshire Unitary Development Plan
SuDS
Sustainable Urban Drainage Systems
FZ
Flood Zone
SWMP
Surface Water Management Plan
Ha
Hectare
TAN15 Technical Advice Note 15
IDB
Internal Drainage Board
TWL
Top Water Level
LFRDP
Local Flood Risk Development Plan
UKCIP
United Kingdom Climate Impacts Programme
LLFA
Lead Local Flood Authority
WW
Welsh Water
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1.0
INTRODUCTION
1.1
Planning Policy Wales Context
1.1.1
All forms of flooding and their impact on the natural and built environment are material
planning considerations. Planning Policy Wales (PPW) sets out the Government’s objectives
for the planning system, and how planning should facilitate and promote sustainable
patterns of development, avoiding flood risk and accommodating the impacts of climate
change.
1.1.2
Government policy with respect to development in flood risk areas is contained within the
Planning Policy Wales, Technical Advice Note 15, (TAN15) ‘Development and Flood Risk’
which was issued in July 2004.
1.2
Technical Advice Note 15 (TAN15)
1.2.1
Technical Advice Note 15: Development and Flood Risk (TAN15) provides technical guidance
to supplement the policy’s set out in PPW with regards to ‘development and flood risk’.
1.2.2
A framework is provided to enable new development to be considered appropriately with
regards to arising risks of fluvial and tidal flooding along with risks associated with additional
run-off from development in all locations (see Appendix I).
1.2.3
TAN15 builds on ‘Flooding in Wales’ published by the Natural Resources Wales in March
2001 in response to the October/November floods of 2000.
1.3
Site Context
1.3.1
This Flood Consequence Assessment has been prepared to support an outline planning
application for the construction of a residential development situated off Corwen Road,
Coed-Talon.
1.3.2
The proposed development site is identified as being located within Flood Zones A, B and C2;
therefore a FCA is required to justify that the proposed development is appropriate with
reference to the compliance set out in TAN15 (checklist included in Appendix A).
1.3.3
All New development taking place within the classified Flood Zones must provide
justification that;
The consequences of flooding to that development and elsewhere have been fully
considered and implemented against for the lifetime of the development;
No increase in flooding will occur to the development site or surrounding area due to
the proposed development including flooding from surface water and sewers;
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1.4
Consultation
1.4.1
The preparation of this report has been undertaken in consultation with the following
interested parties; Flintshire County Council (FCC), Natural Resources Wales (NRW), The
Environment Agency (EA) and Welsh Water (WW).
1.4.2
Planning Policy Wales advises that the LPA should consult with Natural Resources Wales who
will provide advice and guidance on flood issues at a strategic level and in relation to all
planning applications. The Local Planning Authority (LPA), Flintshire County Council, will
make the final decision with regard to any planning permission. Flintshire County Council
also acts as the Lead Local Flood Authority (LLFA).
1.4.3
The Natural Resources Wales were contacted to discuss the nature and extent of
information to be provided in this FCA and for any background knowledge of flood risk
specific to the site (correspondence is included in Appendix F).
1.4.4
Welsh Water Developer Services were contacted to discuss whether WW have any historical
flooding issues in the area or any background knowledge on flood risk specific to the site
(correspondence is included in Appendix G).
1.4.5
Flintshire County Council were contacted to discuss the nature and extent of information to
be provided in this FCA and for any background knowledge of flood risk specific to the site
(correspondence is included in Appendix H).
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2.0
EXISTING SITE SITUATION
2.1
Location
2.1.1
The proposed development site is located in Coed-Talon, Flintshire and is directly accessed
off Corwen Road (A5104). The Ordnance Survey National Grid Reference (OS NGR) for the
site is 326823 (Easting), 358978 (Northing) and the nearest postcode is CH7 4TN. The site
location plan is shown in Appendix C and edged in red in Figure 1 below.
2.1.2
The site is bounded; to the north by the undeveloped land, with ‘Ffordd-Y-Bont’ road
beyond, to the east are residential developments off ‘Ffordd-Y-Bont’ road and the ‘A5104’,
to the west lies undeveloped land, to the south lies further developments off ‘Corwen Road’.
Byr Brook
Proposed Development Location
Unnamed
Tributary
Approximately location
of watercourse
A5104
Corwen Road
Figure 1: Aerial Photograph of site (Bing Maps, 2014)
Aerial View of the proposed development (area edged in red)
2.2
Existing and Historical Land Use
2.2.1
The proposed development site is an existing brownfield development, housing ‘SPA Davies
and Sons’; a salvage yards supplying various steel, plant machinery and cladding. The
company recycles most materials including cladding, metals, re-usable steels, storage tanks
and sleepers.
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2.2.2
The south-western boundary and isolated areas along the eastern boundary provide the
only pervious areas of site, with the remaining areas consisting of commercial buildings
and/or areas of hardstanding. No other historical uses were identified during the
preparation of this report.
2.3
Topography
2.3.1
The detailed topographical survey (included in Appendix D) would suggest the site generally
falls from the western boundary to the south-eastern boundary of site. The initial fall from
the western boundary is steep (Figure 2) with the fall through the rest of site understood to
be shallower in comparison (following observations at the site).
Legend:
Site Boundary
Topographic Fall
Open Channel
Culverted Channel
Figure 2: General Topography within Site Based On Observations.
2.3.2
The existing watercourse forms the lowest elevations of site and runs (culverted in sections)
within the boundaries from the west and south to the east. The watercourse is considered to
be open channel on the topographical survey along the south/western and eastern
boundaries.
2.3.3
A site walkover identified that the open channel located on the eastern boundary is
considerably lower than site due to a steep, vegetated embankment. The open channels in
the south/western areas of site are understood to be situated at a similar elevation to the
surrounding areas of site.
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2.4
Access and Egress
2.4.1
The proposed development site is accessed directly off ‘Corwen Road’, Pontybodkin, to the
west of the ‘Railway Inn’ located along the southern boundary of site and is considered to be
easily accessible.
2.4.2
The guidance set out in TAN15 indicates the importance of early warning and safe access
and egress especially for development of residential nature located within an area identified
as being at flood risk.
2.4
Justification for Development
2.4.1
Planning Policy Wales (5th Ed. – November 2012) states that the Welsh Government is
committed to promoting ‘sustainable development’ by providing for homes, infrastructure,
investment and jobs in a way which is consistent with sustainable development principles
PPW Sec. 2.2).
2.4.2
This FCA has reviewed all sources of flood risk to and from the proposed development site
and has considered appropriate mitigation measures based on the identified sources of risk
making provision for the future uncertainties of climate change.
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3.0
DEVELOPMENT PROPOSALS
3.1
Nature of the Development
3.1.1
This FCA has been prepared to support an outline planning application for the construction
of a residential development complete with access road, external works, footpaths, car
parking, landscaping, boundary walls, fencing, external services and drainage on land to the
north of ‘Corwen Road’ Coed-Talon.
3.1.2
The total site area is approximately 2.900ha and is estimated to be approximately 48%
(1.395ha) impervious at present. The proposed impermeable area of the development is
assumed to decrease to approximately 0.721ha (25%) of the total development area.
Byr Brook
Unnamed
Tributary
A5104
Corwen Road
Approximately location
of watercourse
Figure 3: Existing Site Situation Aerial Photograph (Bing Maps 2014)
3.1.3
There is an existing watercourse running through site, referred to as ‘Byr Brook’, from the
southern boundary to the north-eastern boundary, as shown in Figure 3 above. An unnamed
tributary of ‘Byr Brook’ is understood to converge with the Main River within the boundaries
of site, however the exact location of such is at present unknown as both watercourses are
culverted for the majority of site.
3.1.4
The proposals are to convert the existing large sections of culverts through site back to the
original state as open channels. There will therefore be a requirement for crossing of this
watercourse for any potential access road; this will require a short length of culvert or
ideally a bridge deck. This proposed culvert should be sized sufficiently to cater for the
extreme events up to and including the 1000yr event.
3.1.5
The existing culvert size is 1850mm (downstream) and in order to future proof the capacity,
the proposed culvert would need to be 2.1m (dia.); this has been modelled and determined
adequate. Alternatively to improve the channel morphology it may be preferred that a
bridge deck be constructed over the open channel however this will again be required to be
confirmed during detailed design.
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4.0
TECHNICAL ADVICE NOTE 15 (TAN15)
4.1
Flood Zone Classification
4.1.1
The Welsh Government Development Advice Map (DAM) is to be utilised when considering
and determining flood risk associated with planning future developments within Wales,
these maps are based on extreme flood events outlined by the Environment Agency (EA)
and British Geological Survey (BGS) data (TAN15).
4.1.2
The development advice map identifies three key ‘flood zones’ for consideration, TAN15;
Figure 1 provides detailed definitions of these zones, which are summarised below:
• Flood Zone A
Areas considered to be at little or no risk of fluvial/tidal flooding.
• Flood Zone B
Areas known to have historically flooded based on sedimentary evidence deposits.
• Flood Zone C
Areas considered to be located on floodplain based on EA extreme flood outline data (equal
to or greater than 0.1% fluvial/tidal flooding). This zone is subdivided into:
Zone C1 - Areas considered to be developed and served by significant infrastructure (flood
defences).
Zone C2 - Areas considered to be located within natural floodplain without significant flood
defences.
Legend:
Zone A
Zone B
Zone C1
Zone C2
Figure 4: Development Advice Map Extract (Welsh Government, 2013)
4.1.3
The proposed development site is identified on the DAM to be located within Flood Zones A,
B and C2 as highlighted in Figure 4 above (see Appendix E for details).
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4.1.4
The proposed development site is predominantly considered to be at ‘little or no risk of
fluvial/tidal flooding’ based on the DAM, the south-eastern boundary of site (lowest
elevation) is identified as being within Flood Zone B and C2, therefore consideration is
required for appropriate mitigation within these areas to secure the development site for its
design life.
4.1.5
Review of the historical data would suggest that the flood risk to the southern and eastern
areas of site is primarily due to the presence of the existing watercourses bisecting site, this
area has only one historic incident of flooding (caused by a blockage issue upstream)
whereby debris resulted in flooding to some of the south-eastern portion of site, for
approximately 24 hours.
4.1.6
Consideration is required in compliance with TAN15 for future flood risks to a development
with respect to climate change, all proposals must show that the influences on flood risk due
to climate change has been considered and accounted for through appropriate mitigation
measures.
4.2
Category of Development
4.2.1
TAN15 states that particular types of development may not be considered ‘acceptable’
based on their vulnerability to the consequences of flooding, identified on the Development
Advice Maps (as described in TAN15; Section 5).
4.2.2
The vulnerability of different land uses are described in detail in TAN15 (Figure 2 and Section
5) however there are three key categories as summarised in Table 1 below;
Development
Category
Description
Emergency
Services
Facilities which need to remain operational and
accessible at all times.
Highly
Vulnerable
Development where the ability of occupants to
decide on whether they wish to accept the risk and
manage the consequences associated with flooding
is limited.
Less
Vulnerable
Types
 Hospitals & Ambulance Stations,
 Fire & Police Stations,
 Coastguard Stations.




Residential Developments,
Hotels,
Caravan Parks,
Public Buildings.
Industrial uses where risk to public/environment
from inundation is present.
 Power Stations,
 Chemical Plants,
 Waste Disposal.
Development where the ability of occupants to
decide on whether they wish to accept the risks
associated with flooding is greater than ‘highly
vulnerable category’.




General Industrial,
Commercial Developments,
Utilities Infrastructure,
Transport.
Table 1: Development Category of Vulnerability (Source: TAN15: Section5)
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4.2.3
The development proposals are ‘residential’ in nature and therefore categorized as ‘Highly
Vulnerable’, this nature of use is considered ‘acceptable’ within Flood Zone A providing all
surface water management requirements are conformed to. In order for residential
development to be considered ‘acceptable’ in Flood Zones B and C, site levels are expected
to be checked against water levels data for the extreme (0.1%) flood events. Hydraulic
modelling has confirmed the site to lie within the extents of Flood Zone A.
4.2.4
In order for ‘Highly Vulnerable’ development to be justified it must demonstrate, in
accordance with TAN15 that its location in Zone C;
Is necessary to assist of be part of a local authority regeneration initiative;
or,
Is necessary to contribute to key employment objectives to sustain an existing
settlement or region;
and,
It concurs with the aims of PPW (meeting the definition of previously developed land;
and,
The potential consequences of flooding for the particular development have been
considered;
4.3
Justification
4.3.1
In order for new development to be considered ‘sustainable’ from a flooding perspective it
must;
Be guided to locations at little or no risk from all sources of flooding and must not cause
such flood issues to neighbouring developments;
Consequences of all sources of flooding to and from the proposed development must be
managed and justified with reference to TAN15 guidance (Section 7 & Appendix 1) ;
Provision for future changes in flood risk must be considered taking into account the
uncertainties of climate change where they can be anticipated;
4.3.2
A TAN15 requirement checklist for assessing flooding consequences is included in Appendix
B which summarises the key requirements as identified within TAN15; Appendix 1.
4.3.3
The proposed site is currently a developed brownfield site of commercial nature, the
proposals suggest re-development of this highly impervious site into a residential
development incorporating landscaped and open space areas.
4.3.4
The nature of the proposals would suggest an opportunity to reduce the flood risk to the site
and surrounding area from fluvial, pluvial and surface water flooding; an increase in
permeability of site would furthermore provide a betterment on the existing surface water
management situation. Furthermore improvements in water quality, biodiversity and
contamination risks would be achieved due to the proposals.
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4.3.5
In light of the identified flood risk, the proposed residential development will be steered to
those areas within site considered to be at least risk using an intra-sequential approach to
flood risk in compliance with TAN15.
4.4
Acceptability Criteria
4.4.1
Various acceptability criteria are identified within TAN15; Section 7 based on the nature and
scale of the proposals, these criteria are used to determine whether the proposed
development is ‘acceptable’ with regards to the predicted consequences of flooding.
4.4.2
The acceptability criteria for ‘Highly Vulnerable’ development proposed in Flood Zone A is
that the proposed development will cause no increase in flood risk (from all sources) to the
immediate and surrounding areas (see Appendix I for TAN15 summary of policy
requirements).
4.4.3
The acceptability criteria for ‘Highly Vulnerable’ development proposed in Flood Zone B is
that;
The development has acceptable consequences for it nature of use;
The occupiers are aware of the flood risk;
Escape and evacuation routes are present;
Effective flood warning and emergency planning is provided;
No increase in flood risk elsewhere due to the proposals;
4.4.4
TAN15 indicates that the flooding consequences associated with ‘Highly Vulnerable’
development proposed within Flood Zone C consider the criteria indicated for the previous
Flood Zone Classifications (stated in 4.3.2 & 4.3.3) along with the criteria stated below;
The flood defences are adequate;
Agreement for construction and maintenance costs are secured (where feasible);
Proposed dwellings have flood resistant design implemented;
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5.0
SOURCES OF FLOOD RISK
5.1
Fluvial & Tidal Flood Risk
5.1.1
Information relating to the flood risk at the site has been obtained from the Welsh
Government’s Development Advice Map (DAM) and Natural Resources Wales (see Appendix
F for full details).
Fluvial Flooding
5.1.2
‘Byr Brook’ is understood to flow through the proposed development site from the southern
boundary to the eastern boundary before continuing its course through ‘Nant Wood’ (northeast of site) into the River Alun.
5.1.3
Some sections of ‘Byr Brook’ are open channel within the boundaries of site however it is
noted that the majority of the watercourse has been culverted through site to allow for its
existing land-use.
5.1.4
An Unnamed Tributary of ‘Byr Brook’ is understood to flow from the west of site joining the
brook within the boundaries of site, the exact location of this confluence in unknown due to
large sections of the watercourse being culverted through site.
5.1.5
The site is considered to be predominantly at ‘very low’ risk of fluvial flooding, based on the
EA Flood Mapping Data. The small area along the south and eastern boundaries are shown
to have ‘low’ to ‘medium’ flood risk; which is understood to be associated with the location
of the watercourses and the lowest elevations within site.
5.1.6
The DAM indicated a small proportion of site to be located within Flood Zones B and C2,
therefore correspondence with NRW and mapping data was requested.
Proposed
Development Location
Figure 5: Natural Resource Wales Fluvial Flood Zone Extract (NRW 2014)
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5.1.7
As indicated in Figure 5 (preceding page), part of the proposed development site
(southern/eastern boundary) is identified as being at risk during the 1 in 1000 year and 1 in
100 year extreme storm events and therefore considered to lie within Flood Zone C2, due to
the lack of significant infrastructure (flood defences).
5.1.8
Review of the Flood Estimation Handbook (FEH) CD-ROM identifies the catchment to be
3.46km (sq.). The fluvial flood risk to the majority of the site is understood to be relating to
the watercourse bisecting site, the lowest elevations surrounding the watercourse
channels/culverts are considered to have a higher risk in comparison to the remainder of
site and therefore development should be wherever possible steered away from these
areas.
Hydraulic Assessment
5.1.9
Correspondence with NRW indicated that there is no model information or flood defence
information for the proposed development site (see Appendix F), therefore the potential
depths of inundation within site cannot be accurately ascertained and further modelling was
required.
5.1.10 Following detailed discussions with NRW it was agreed that 1D modelling of the
watercourses bisecting site be undertaken as part of the FCA including modelling of the
upstream culvert of Byr Brook to the south of site.
5.1.11 The watercourse bisecting site is understood to be predominantly culverted within the site;
with the exception of a small open section along the southern, south-western and northeastern boundaries. The topographical survey gives indication of the open channel sections,
along with an indication of culvert dimensions; the direction and location of the culverted
sections have been assumed for the purpose of this FCA.
5.1.12 It is understood that the main river reach is that of ‘Byr Brook’ which enters site along the
Sothern boundary, a smaller, Unnamed Tributary is understood to converge with the main
system within site. The exact location of such convergence, is assumed at present, as the
point of convergence is within the existing culverted sections and not apparent from above
ground.
Method
5.1.13 The catchment descriptors were identified from the FEH CD-ROM for the catchment just
downstream of the site, this results in potential flows being slightly over-estimated and in
turn results in a more conservative model from a flood risk perspective. The FEH Catchment
descriptors are included in Appendix J. The Revitalised FSR/FEH Rainfall Run-Off Method
(ReFH) was applied based on catchment descriptors; these are considered to represent
conservative flow estimates (i.e. adopts the precautionary approach).
5.1.14 This study has considered the; 1 in 1 year (Q1), 1 in 100 year (Q100), 1 in 100 year + 20%
allowance for Climate Change (Q100+CCA) and the 1 in 1000 year (Q1000) flood flows along
the watercourses. The peak flow estimates are shown in Table 2 (subsequent page); full
details are shown in Appendix Q.
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RETURN
PERIOD
(YEARS)
1 in 1
1 in 100
1 in 100 +
20% (CCA)
1 in 1000
3
FLOW
REF.
Q1
Q100
Q100 +
CCA
Q1000
REACH 1 – BYR BROOK
UPSTREAM
1.1
4.5
FLOW ESTIMATE (M /S)
REACH 2 – UNNAMED
TRIBUTARY
0.3
1.5
REACH 3 - BYR BROOK
DOWNSTREAM
1.4
6.0
5.4
1.8
7.2
8.0
2.7
10.7
Table 2: ReFH Flow Estimates
5.1.15 A steady state 1 dimensional (1D) model of the watercourses was developed using HEC-RAS
v4.1 which solves the Energy Equation using the Standard Step Method. A topographical
survey of the site was undertaken and cross sections through the watercourses and adjacent
land were recorded.
5.1.16 A schematic view of the modelled reach is shown in Figure 6 (below), the watercourse
profile and cross sections are included in Appendix R. As the existing culverts have different
upstream/downstream dimensions and the location at which such a change occurs is
unknown, it was concluded following discussions with JBA consulting that the existing
culverts should be modelled to represent each culvert dimension and the culvert with the
least capacity was utilised to reflect the existing situation onsite, to follow a more
conservative approach.
Figure 6: Model Schematic HEC-RAS v4.1 - Existing (Betts Associates 2014)
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5.1.17 Upstream of site the channel of Byr Brook is considered to be lined/built up and includes
multiple obstructions, with highly vegetated banks. Upstream of the Unnamed Tributary is
considered to be more natural, although obstructions are still present with the banks being
predominantly highly vegetated (see Appendix P for photographs of watercourse).
Downstream of site Byr Brook is considered to be more natural, with the steep banks and
mixed vegetation.
5.1.18 Roughness coefficient allocations were based on information obtained during a site
walkover undertaken in July 2014 by employees of Betts Associates Ltd, and photographic
evidenced reviewed as part of this FCA including that provided by Geomatic Surveys Ltd.
Within the model the roughness coefficient for the existing culverts has been applied based
on the observations of the structures.
5.1.19 The upstream and downstream boundary conditions were assumed normal depth, based on
the average gradient through the study area of 0.0207 for Reach 1, 0.0437 for Reach 2 and
0.0163 for Reach 3.
Results
5.1.20 The hydraulic modelling results including; a schematic plan, longitudinal profiles, cross
sections and modelling output tables for all reaches (indicating Top Water Levels (TWL) for
all of the aforementioned storm events) are included in Appendix R.
5.1.21 Based on the Hydraulic Model, it is considered that the whole of site would remain flood
free during the design period event (Q100+CCA event), due to sufficient capacity within the
existing culverts onsite (See Figure 7 below). The water surface elevation varies through site
based on the location and proximity to the watercourse; however no out of channel flooding
is anticipated, based on the simulations, within the extents of site.
Figure 7: 1D Hydraulic Model Profile Plot Output (Betts Associates 2014)
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5.1.22 The existing Unnamed Tributary culvert (no. 3) bisecting site, is considered to have sufficient
capacity to allow flows from the annual event although some minor out of channel flooding
would be anticipated during the Q100, Q100+CCA and Q1000 year events (see Figure 8
subsequent page). The anticipated flows during the Q100+CCA event would be
approximately 0.44m3/s (derived from the 1D hydraulic model).
Figure 8: 1D Hydraulic Model Profile Plot Output (Betts Associates 2014)
5.1.23 The existing downstream culvert, bisecting site along the eastern boundary, is considered to
have sufficient capacity to take the predicted flows up to and including the 1 in 100 year
return period event with an allowance for Climate Change (Q100+CCA), with no above
ground flows anticipated for the design period event (illustrated in Figure 8 above).
5.1.24 The existing Byr Brook culvert upstream of site is considered to have insufficient capacity to
take the flows generated during the Q100, Q100+CCA and Q1000 year events (Figure 8).
Some out of channel flows (approximately 2.41m3/s) would be anticipated during the design
period event (Q100+CCA) upstream of site, due to capacity issues within the existing
upstream culvert.
5.1.25 It is understood that the most likely location for the existing system to reach exceedance
would be the inlet of this upstream culvert (offsite) and therefore identification of the
potential flood flow routes has been undertaken, utilising Ground Levels data (LiDAR DTM)
and a topographical survey. Any water not able to enter the existing system would flow
safely away from site, utilising the existing drainage systems within the highway (Corwen
Road) to the south of site (Figure 9 on the subsequent page; Appendix T).
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Figure 9: Overland Flood Flow Routing Plan extract (Betts Associates 2014)
5.1.26 Sensitivity testing was carried out on the model parameters to determine the effects on the
simulated flows and water levels due to controlled changes in accordance with best practice.
The flow rates for the 1 in 100 year return period event were increased and decreased by
20% for each of the simulated reaches. The boundary conditions for each of the simulated
reaches were increase and decreased by 20% for all the simulated storm events. The
Manning’s n Values (channel roughness) and the weir coefficients were increased and
decreased by 10% for all the simulated storm events (see Appendix T for outputs).
5.1.27 No increase/decrease in water surface elevation was observed when altering the flow rates
for the Q100 year event by 20%, thus no increase in flood risk would be anticipated with this
variable and no out of channel flooding is anticipated within the main boundaries of site. No
change in the anticipated flood risk to site is understood to result from
increasing/decreasing the boundary conditions (slope depth) by 20%.
5.1.28 An insignificant increase in water surface elevation (0.01m) is observed upstream of Reach 2
(Unnamed Trib.) and Reach 1 (Byr Brook), when increasing the roughness coefficients with
no change/decrease in water surface elevation observed elsewhere within the system.
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Similar observations were witnessed when the weir coefficients for the reaches were
increased and decrease by 10% with no anticipated increase in flood risk in the downstream
culvert and an insignificant increase in flood risk within the upstream Byr Brook and
Unnamed Tributary reaches.
5.1.29 Although the chance of blockage within the existing structures is considered to be
significantly reduced due the sizes of the existing inlets, various blockage scenarios were
undertaken and reviewed as part of the analysis. During the 25% and 75% blockage
scenarios (tested on all structures individually and combined); the water surface elevation is
understood to either remain the same or be slightly reduced along the majority of site (see
Appendix U for outputs).
5.1.30 During both the 25% and 75% blockage simulation on Culvert 2 (Unnamed Trib.); an increase
in water surface elevation (0.04/0.05m) is anticipated along Byr Brook between the
upstream culvert and the downstream culvert. Irrespective, following review of the available
topographic information no out of channel flood would be anticipated with regards to the
Unnamed Tributary and downstream Byr Brook. Any overland flooding generated by the
upstream culvert on Byr Brook would be intercepted prior to reaching site and as such there
is no anticipated increase in flood risk to site.
5.1.31 It is understood that as part of the proposals, the existing onsite culverts (Culverts 2 and 3)
are to be removed and a natural channel restored, this has therefore been simulated using
the most appropriate profiles and interpolated cross-sections, maintain a steady gradient fall
from the existing open channel locations (see Figure 10 on the subsequent page; Appendix V
for outputs).
5.1.32 The proposed open channel has a positive effect on the water surface elevation levels for
the upstream Unnamed Trib. and Byr Brook, reducing in some locations the simulated
surface water elevation and reducing upstream flood risk. The proposed open channel
simulation did not show any significant changes to the downstream water surface elevation
along Byr Brook and therefore no increase in flood risk would be anticipated.
5.1.33 The proposals are understood to be solely residential in nature therefore Finished Floor
Levels (FFL) should be set a minimum of 600mm above the Q100+CCA event to mitigate for
any potential fluvial flooding and safeguard the development for its design life (100yrs). The
FFL will vary based on the location within site and the proximity to the watercourse, detailed
design should account for this variation through site and set FFL’s to reflect such.
5.1.34 No displacement of floodplain is proposed therefore no compensatory storage is required.
5.1.35 In view of the proposals to remove the existing culverted lengths within site, it is anticipated
that a new short length would be required (under the access road) this will be size
appropriately during detailed design to cater for the predicted flows.
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Figure 10: Model Schematic HEC-RAS v4.1 – Proposed (Betts Associates 2014)
5.2
Tidal Flooding
5.2.1
The coast is located approximately 31km to the north-west of the proposed development
area, with the River Dee Estuary located approximately 15km to the north.
5.2.2
Due to the distance from the coast and estuarine waterways the risk of flooding from tidal
sources is considered to be ‘very low’ as identified in the EA’s Flood Mapping data shown in
Figure 4 (pg. 22).
5.2.3
Consultation with NRW confirmed that site is not considered to be at risk from tidal related
flooding, correspondence has been included within Appendix F.
5.3
Groundwater Flood Risk
5.3.1
In general terms groundwater flooding can occur from three main sources: ‐ raised water
tables, seepage and percolation and groundwater recovery or rebound.
5.3.2
If groundwater levels are naturally close to the surface then this can present a flood risk
during times of intense rainfall.
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5.3.3
Seepage and percolation occur where embankments above ground level hold water. In these
cases water travels through the embankment material and emerges on the opposite side of
the embankment. At present there are no reported problems with groundwater flooding.
5.3.4
Groundwater recovery / rebound occurs where the water table has been artificially
depressed by abstraction. When the abstraction stops the water table makes a recovery to
its original level. There is the potential for groundwater flooding in low lying areas where
groundwater levels have been depressed below their pre‐pumping conditions, where these
were at or close to ground level. As with the seepage scenario the likelihood of flooding
from this source is considered to be low.
5.3.5
The EA’s online mapping data indicates that the site is underlain by a ‘Secondary A’ aquifer
as highlighted in Figure 11 below (see Appendix F for full details). No historical groundwater
flooding of the site has been identified during consultation with the various interested
parties.
Proposed Development
Location
Legend:
Figure 11: Groundwater Designation Map Extract (Environment Agency, 2014)
5.3.6
Irrespective, setting Finished Floor Levels of the proposed development to a minimum of
150mm above the external levels (following any re-grade) would mitigate any future risks of
flooding from this source.
5.4
Artificial Sources of Risk
5.4.1
TAN15 suggests that in order for new development to be ‘justified’ then all sources of flood
risk must be considered both to and from the development site and implemented against.
Reservoirs
5.4.2
Figure 12 (subsequent page) shows an extract of the EA’s online Reservoir flood map;
Appendix F shows the EA’s reservoir flood map in full.
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Unnamed
Tributary
Byr Brook
Approx. Location
of the Culverted
Sections
Legend:
Reservoir Flood Risk: Maximum Extent
Figure 12: Reservoir Flood Map Extract (Environment Agency, 2014)
5.4.3
The proposed development site is located approximately 3.1km south-west of the nearest
EA identified reservoir (those holding over 25,000cu.m), this combined with the natural
topography of the area the associated risk of flooding from this source is considered to be
‘low’.
5.4.4
There is an unidentified lake approximately 0.7km north-west of the proposed development
site, due to its size and proximity from the development site, the associated flood risk from
this source is also considered to be ‘low’.
Canals
5.4.5
The nearest identified Canal is the ‘Shropshire Union Canal’, located approximately 19.3km
north-east of the proposed site; as such the risk from this source is considered to be ‘very
low’.
5.5
Surface Water Flood Risk
5.5.1
Surface water flooding occurs when rainwater is unable to drain away through the normal
drainage systems or soak into the ground, but lies on or flows over the ground instead. This
section will consider the surface water flood risks associated with overland run-off (pluvial)
and sewers.
5.5.2
An increase in impermeable areas through development can reduce percolation rates at
source, therefore increasing surface water run-off. If this run-off is not controlled effectively
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it can increase the frequency and extent of localised flooding in neighbouring areas of the
catchment.
5.5.3
TAN15 states therefore that ‘The aim should be for new development not to create
additional run-off when compared with the undeveloped situation and re-development to
reduce the overall run-off where possible’ (Section 8.3).
5.5.4
Due to the proposed development site being located within Flood Zones A, B and C2 there is
consideration needed into appropriate management of surface water run-off generated by
the proposals.
5.5.5
The Environment Agency’s online surface water flood map indicates that the proposed
development site is considered to be predominantly at ‘Very Low Risk’ from surface water
flooding as highlighted by the lack of blue shading within the site boundaries in Figure 13
(below). The areas indicated to be at ‘low’, ‘medium’ and ‘high’ risk from surface water
flooding are associated with the lowest elevations and the location of the watercourse
within site.
Approx. Location
of the Culverted
Sections
Unnamed
Tributary
Byr Brook
Legend:
Very Low
Low
Medium
High
Figure 13: Surface Water Flood Map Extract (Environment Agency, 2014)
5.5.6
More detailed mapping information was requested from NRW, correspondence confirmed
that the proposed site is considered to be predominantly at ‘Very Low Risk’ from surface
water flooding during the 1 in 30 and 1 in 100 year events, as indicated in Figures 14 and 15
(subsequently). The identified risk areas again correspond with the areas of most
hardstanding, lowest topography and location of the culverted watercourse through site.
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Figure 14: Flood Map for Surface Water 1 in 30 Map Extract (Natural Resources Wales 2014)
5.5.7
When reviewing the received NRW data for surface water flooding during the 1 in 1000 year
event the proposed development site is predicted to experience more surface water
flooding than during the other review events (Figure 16; on the subsequent page, grey
shading).
5.5.8
The north and western boundaries are understood to not be predominantly inundated; the
predicted extents of surface water flooding during the 1 in 1000 year event, is the majority
of the south-eastern boundary of site. This area is understood to be much flatter than the
surroundings areas and ponding is more likely to occur in these areas.
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5.5.9
The nature and scale of the development proposals (residential) are understood to offer
significant improvement on pervious areas within site which may aid in a reduction of the
associated surface water flood risks. Irrespective, setting Finished Floor Levels a minimum of
150mm above the external levels following any re-grade should reduce the associated risk of
surface water flooding in these areas.
Pluvial Flooding (Overland Run-off)
5.5.10 Intense rainfall that is unable to soak into the ground or enter drainage systems can run‐off
land and result in flooding. Local topography and the land use can have a strong influence on
the direction and depth of flow. Large catchment areas are particularly prone to this type of
flooding. The volume and rate of overland flow from land can be exacerbated if
development increases the percentage of impermeable area.
5.5.11 There is little likelihood of significant pluvial flows impacting on the proposed development
site, current understanding of the natural topography of site and the surrounding areas
means that existing flows are likely to travel towards the eastern boundary of site towards
the A5104.
5.5.12 Any overland flows generated by the proposed development must be carefully controlled;
safe avenues of overland flow away from the existing and proposed dwellings is advised.
Sewer Flooding
5.5.13 In urban areas, rainwater is frequently drained into surface water sewers or sewers
containing both surface and waste water known as ‘combined sewers’. Foul water flooding
often occurs in areas prone to overland flow and can result when the sewer is overwhelmed
by heavy rainfall and will continue until the water drains away. It can also occur when the
sewer becomes blocked or is of inadequate capacity, this could lead to there being a high
risk of internal property flooding with contaminated water.
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5.5.14 Consultation with Welsh Water (WW) did not identified any existing sewer flood risk issues
or historical flooding within the vicinity of the proposed development site (correspondence
included in Appendix G).
5.6
Historical Events of Flooding
5.6.1
An Internet based search for flooding events did not recall any historical flooding to the
immediate development site and surrounding area including review of the Chronology of
British Hydrological Events.
5.6.2
There is no Strategic Flood Consequence Assessment available for the area and the Flintshire
County Council’s Preliminary Flood Risk Assessment did not identify any historic flood events
to the proposed development area (some mapping information has been included in
Appendix O).
5.6.3
The River Dee Catchment Flood Management Plan (2010) indicates the potential for surface
water, fluvial and sewer flooding within the surrounding agricultural areas to Mold during
times of excess rainfall. However no specific reference is given to the area of CoedTalon/Pontybodkin.
5.6.4
Consultation with FCC and WW furthermore failed to highlight any historical flooding events
pertinent to this FCA (correspondence included in the Appendices).
5.6.5
Consultation with NRW identified one recorded historic flood event in 2000, associated with
the tributary of ‘Byr Brook’ within the site boundaries (Figure 17 below); the event lasted for
approximately 24 hours and effected 5 properties.
Proposed
Figure 17: Flood Event Outline Map Extract (Natural Resources Wales 2014)
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5.6.6
It is understood that the flooding occurred due to the presence of debris blocking the inlet,
fly-tipping upstream and the presence of services pipes crossing the watercourse. No other
historical flood incidents have been identified, following removal of debris and relocation of
the services pipes to beneath the brook.
5.7
Flood Warning and Evacuation
5.7.1
As the site is identified to be located within Flood Zone C, safe emergency access and egress,
along with appropriate flood warning needs consideration in compliance with TAN15.
Flood Warning
5.7.2
Although the majority of site is indicated on the DAM to be located within Flood Zone A,
with the lower elevations being located within Flood Zones B and C; hydraulic modelling has
confirmed the site lies wholly within Flood Zone A with the exception of the watercourse
channels themselves. The residential development is advised to take place in those areas
deemed at least risk from flooding within the boundaries of site. Figure 18 (below) indicates
that part of the proposed development site is located within a NRW ‘Flood Alert Area’.
Proposed
Figure 18: Flood Warning Map Extract (Environment Agency 2014)
5.7.3
This alert relates to the River Alyn catchment which is located approximately 1.8km northeast of the site and not the catchment associated with ‘Byr Brook’, therefore a site specific
evacuation plan may be determined necessary during detailed design to increase community
preparedness at the site.
5.7.4
Irrespective, it would be recommended, due to the nature of the development proposals
that all future residents within the identified alert area be aware of the associated flood risks
to site and advised to sign up to the free ‘Floodline Warning Direct Service’ (https://fwd
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.environment-agency.gov.uk/app/olr/home) to give them warning of potential future
flooding within the vicinity of site.
5.7.5
To furthermore improve future resident’s resilience to flooding it would be recommended
that the importance of emergency planning is portrayed and a copy of the emergency flood
advice leaflet (if applicable) is made available to make them fully equipped to carry out
emergency activities.
Evacuation
5.7.6
In severe conditions, the authorities may decide to evacuate. Information will be given over
the usual channels and/or by local hailer. It is possible that roads in the area may be flooded
by surface water/groundwater flooding before fluvial flooding occurs. Such flooding may
impact the road network in the area and not all routes may be accessible. In such an event
the protection of evacuation routes will become a critical priority; once flooded only
adequately equipped vehicles may be able to negotiate these roads.
5.7.7
Flintshire County Council may activate a Helpline in severe events to provide information,
advice and guidance to the public in relation to evacuation arrangements, welfare,
temporary accommodation etc.
5.7.8
The proposed evacuation route is indicated in Figure 19 (below); this is the most direct route
from site to higher ground. The initial evacuation route leads from the proposed
development site into ‘Corwen Road’, before heading south-west away from the extents of
the floodplain. Residents would be strongly advised to evacuate during the extreme events,
however if evacuation is deemed not possible or to dangerous it is recommended that
occupants retreat to the first floor.
LEGEND
Prop. Evacuation Route
Figure 19: Evacuation Route Plan (Betts-Associates 2014)
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Emergency Access and Egress
5.7.9
The site is confirmed to lie within Flood Zone A and not within the extents of the floodplain,
based on the hydraulic modelling. The majority of site is elevated in comparison with the
proposed access road on the south-eastern boundary of site. Based on the nature of the site,
the only feasible access route will be situated within the area indicated as Flood Zone C2 and
B (along the south-eastern boundary), therefore consideration is required for safe access
and egress during the extreme storm events.
5.7.10 The proposals are to open up the existing culverted sections of the watercourse within site,
where possible; which may offer potential for a reduction in flood risk within the southeastern boundary portion of site. Proposals to open the majority of the culverted sections to
their natural state, and the addition of a newly adequately sized (2.1m dia.) small length,
culverted section should effectively mitigate the flood risk for the extreme flood events up
to and including the 1000 year event.
5.7.11 The hydraulic assessment undertaken on the existing watercourses as part of the FCA,
indicate the predicted water surface elevations for various locations within the boundaries
of site. In accordance with TAN15 flood depths should be no greater than 600mm along the
proposed access road and therefore detailed design should determine the most appropriate
locations within site for access and egress as no planning layout is currently available
(A1:15).
5.8
Flood Risk Mitigation Measures and Residual Risks
5.8.1
TAN15 guidance recommends that any development proposals in areas at identified risk
consider the five key principles listed below with regards to appropriate mitigation
measures:
Minimal risk to life;
Minimal disruption to people;
Minimal potential damages to property;
Minimal impact of flood risk in general due to the development proposals;
Minimal disruption to natural heritage;
5.8.2
With reference to TAN15, residential development should be wherever possible steered
towards areas at least risk, the majority of the proposed development site is located within
Flood Zone A and no specific flood risk mitigation measures are required within these areas.
5.8.3
Any development taking place within Flood Zones B or C will however require some level of
mitigation in order to safeguard the development. The primary mitigation measure
proposed within Flood Zones B and C, is to set finished floor levels (FFL) for the site a
minimum of 600mm above the 1% AEP+CCA event. This specific water level will need to be
calculated during the detailed design stage, however the detailed topographic survey of site
and undertaken hydraulic 1D model, indicate this is feasible from a levels perspective.
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5.8.5
Where levels raising within Flood Zone C occurs (more specifically the 1% AEP+CCA event),
there is a necessity to provide compensatory flood storage onsite, it is understood that there
is scope to achieve this storage requirement in the area within site; the specific volumes
required for any displacement should be calculated during the detailed design stage.
5.8.7
The existing culverted sections of watercourse through site are proposed to be opened up,
this allows for a more natural course to be achieved which is considered to reduce the fluvial
flood risk associated with previous capacity issues. Added benefits of a natural open channel
through site would be the introduction of a green buffer zone, improvements in water
quality, biodiversity and visual aesthetics within the wider area.
5.8.8
There will therefore be a requirement for crossing of this watercourse for any potential
access road; this will require a short length of culvert or ideally a bridge deck. The existing
culvert size is 1850mm (downstream) and in order to future proof the capacity; the
proposed culvert would need to be 2.1m (dia.). Alternatively to improve the channel
morphology it may be preferred that a bridge deck be constructed over the open channel
however this will again be required to be confirmed during detailed design.
Mitigation Measures: Summary
5.8.9
It is advised that Finished Floor Levels (FFL) be set a minimum of 600mm above the 1% AEP 1
in 100 year) event with an allowance for climate change to mitigate for potential fluvial
flooding from the watercourse, the specific water level will need to be calculated during the
detailed design stage. Compensatory storage would be required onsite should levels within
Flood Zones C (1%AEP+CCA event) be raised, the exact volumes of such will be required to
be calculated during the detailed design stage.
5.8.10 Setting Finished Floor Levels a minimum of 150mm above the external levels following any
re-grade should mitigate any risk of flooding from a variety of sources, including
groundwater, surface water, sewer and pluvial flooding.
5.8.11 As with any development it is also advised that external levels fall away from the properties
and any overland flows generated by the proposals are carefully controlled (safe avenues
away from any existing and proposed buildings is advised), see Appendix N for overland
flood flow routing plan.
5.8.12 To minimise the flood risk to the neighbouring developments and conform to the guidance
set out in TAN15, it is proposed that surface water run‐off generated by the proposed
development be managed effectively, ideally with the peak rates of run‐off being restricted
to the equivalent of the pre‐development situation.
5.8.13 Opportunities to implement sustainable drainage systems may arise (following further
investigations) which offer the possibility to further reduce the surface water discharge
generated by the proposals; conforming with the guidance set out in TAN15.
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5.8.14 The development and its drainage systems should be designed to cope with intense storm
events up to and including the 100 year return period rainfall event with an allowance for
Climate Change (CC).
5.8.15 It is proposed that this be achieved using a Hydrobrake® flow control device with
stormwater storage being provided to prevent overland run-off from leaving site for events
up to and including the 100yr event with a 30% allowance for climate change.
5.8.16 As with any drainage system blockages within either the foul or surface water system have
the potential to cause flooding or disruption. It is important that should any drainage
systems not be offered for adoption to either the Water Company or the Local Authority
then an appropriate maintenance regime should be scheduled for these private systems.
Residual Risks: Summary
5.8.17 The development is accessible for emergency access and egress during times of extreme
flooding provided the FFL are set to safeguard the proposed development for its design life;
TAN15 guidance states a maximum flood depth of 600m is acceptable along the
access/egress route. Furthermore the new proposed short length of culvert must be sized
with sufficient capacity to cater for the 1000 year return period events to provide safe
access and egress into site, to be determined during detailed design.
5.8.18 If an extreme rainfall event exceeds the design criteria for the drainage system it is likely
that there will be some overland flows that are unable to enter the system, it is important
that these potential overland flows are catered for within the proposed planning layout in
the event that the capacity of the drainage system is exceeded.
5.8.19 The residential nature of the proposals will result in the opportunity to improve the visual
aesthetics and biodiversity of the surrounding area and furthermore result in a reduction in
the risk of contamination during flood events which may improve the water quality
downstream of site.
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6.0
CLIMATE CHANGE
6.1
There are significant indications that the UK climate is changing; the nature of this change
will vary based on regional and catchment differences, consensus is that effects will become
more pronounced over the coming decades.
6.2
The UK Climate Impacts Programme (2002) predicts the key differences to UK climate being
the potential for a 30% increase in winter precipitation by 2080. With reference to TAN15
the most likely effects to be experiences within Wales are;
Increases in sea levels;
Greater inflow into estuaries and the sea;
Significant changes in rainfall patterns seasonally;
Increased evapotranspiration;
6.3
Current expert opinion indicates the likelihood of more frequent short duration and high
intensity rainfall events and the addition of more frequent periods of long duration rainfall
meaning future flooding events will have a greater impact on the environment and society.
6.4
Making ‘provisions’ for these anticipated future changes to flood risk due to the
uncertainties surrounding climate change is considered to be an important ensuring future
‘sustainable development’ within Wales as identified within TAN15; Section 2.1.
6.5
Any increase in the level of flood risk to the proposed development from climate change is
likely to be related to the increase in rainfall intensity and duration and its impact upon the
surface water drainage system (due to its location from the coast/estuary).
6.6
Climate Change should be accounted for within the design and it is recommended that an
increase in peak rainfall intensity of 30% is allowed for as identified within TAN15.
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7.0
SUSTAINABLE URBAN DRAINAGE SYSTEMS (SuDS)
7.1
Sustainable Drainage Systems (SuDS) have the ability to address three core objectives; water
quantity, water quality and amenity value. With the appropriate system specified, all three
core objectives can be satisfied.
7.2
In accordance with TAN15, SuDS should be specified with all new developments; wherever
feasible, to manage surface water run-off from site. Preference should always be given to
SuDS over the traditional methods of buried sewers wherever possible and practical in order
to reduce the overall burden of downstream sewerage systems and watercourses.
7.3
TAN15 suggests the most effective SuDS systems incorporate both soft and hard engineering
solutions to control surface water run-off at source, in turn reducing the overall quantity of
and delaying its discharge to the most appropriate source.
7.4
The proposals for the development site indicate a ‘residential’ development therefore it is
proposed that opportunities should be taken to provide soft landscaping where at all
possible on site to assist in minimising surface water run‐off. Added benefits include
biodiversity and visual enhancements.
7.5
Runoff from car parking areas and roads could be conveyed through swales, permeable
pavements, bio‐retention areas and petrol interceptors to provide a degree of treatment
before flows are carried to public sewers/watercourse.
7.6
As aforementioned, the proposals indicate that the existing culverted sections of the
watercourse through site are to be opened up into a formal watercourse feature within site,
this feature could be enhanced further following re-profiling to form part of a broader
wildlife corridor promoting biodiversity and improving visual aesthetics.
7.7
Any informal green space could be utilised as a multi-use POS area, incorporating SUDs
designs, to provide the required storage for any displacement of flood waters due to the
proposals and/or storage of the surface water run-off due to the proposed restricted
discharge rate. Detailed design will be required to confirm feasibility following further
investigation.
7.8
It is proposed that SuDS systems are considered within the development to manage the
surface water run-off generated by the proposals, the exact SuDS systems will be
determined at detailed design.
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8.0
SURFACE WATER MANAGEMENT
8.1
Pre-Development Surface Water Run-off
8.1.1
For the purposes of determining the existing rate of surface water run‐off the site is
considered to be 52% pervious at present; the total area of the site is considered to be
approximately 2.900ha, with approximately 1.395ha of existing impermeable areas
(Appendix M).
8.1.2
The surface water run‐off rates have been calculated using the IH124 Greenfield run-off
method, utilising rainfall catchment characteristics from the Flood Estimation Handbook
(FEH), details of which are included Appendix J.
8.1.3
The approximate surface water run-off rate generated by the pre-development area based
on the annual return period storm event is 58.1l/s. The approximate surface water runoff
volume generated by the total development area based on the annual return period storm
event is 359.1cu.m; estimated using the FEH rainfall catchment characteristics (6hr duration
event).
8.1.4
The approximate surface water run-off rate generated by the pre-development area based
on the 100 year return period storm event is 173.2l/s. The approximate surface water runoff
volume generated by the total development area based on the 100 year return period storm
event is 1340.7cu.m; estimated using the FEH rainfall catchment characteristics (6hr
duration event).
8.2
Post-Development Surface Water Run-off
8.2.1
The residential nature of the development proposals means that there will be a decrease in
the impermeable areas of the site, due to the existing land-use as a salvage yard.
Impermeable areas are estimated to decrease from approximately 1.395ha to approximately
0.721ha (25%), resulting in decrease in both the volume and the peak rate of surface water
run‐off.
8.2.2
The approximate surface water run-off rate generated by the impermeable area based on
the annual return period storm event is 28.3l/s. The surface water run-off rate generated by
the impermeable area based on the 1 in 100 year return period storm event, with a 30%
allowance for climate change is 110.9l/s (refer to Appendix K).
8.2.3
The approximate surface water runoff volume generated by the impermeable area, based
on the annual return period storm event is 118.2cu.m; estimated using the FEH rainfall
catchment characteristics (6hr duration event). The approximate surface water runoff
volume generated based on the 1 in 100 year return period storm event is 609.2cu.m;
estimated using the FEH rainfall catchment characteristics (6hr duration event).
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8.3
Methods of Surface Water Management
8.3.1
In order for the development proposals to be justified in line with the guidance set out in
TAN15, the development must not increase flood risk elsewhere within the catchment and
where possible offer improvement of the pre-development situation, therefore surface
water management is a key focus (see TAN15: Section 8).
8.3.2
At present the site is identified as being a brownfield development comprising ‘SPA Davies
and Sons’ salvage and recycling yard, which is understood to supply various steel, plant
machinery and cladding. The total site area is approximately 2.900ha and predominantly
made up of large areas of hardstanding presently (see Appendix P for photographic
evidence), the site is considered to be 52% pervious at present.
8.3.3
The assumed impermeable area of the development is assumed to decrease from
approximately 1.395ha to 0.721ha, 25% of the total site area.
8.3.4
There are three methods that have been reviewed for the management and discharge of
surface water detailed below; these may be applied individually or collectively to form a
complete strategy. They should be applied in the order of priority listed below;
Discharge via infiltration
Discharge to watercourse
Discharge to sewerage system
8.4
Discharge via Infiltration
8.4.1
Any impermeable areas that can drain to soakaway or an alternative method of infiltration
would significantly improve the sustainability of any surface water systems and be therefore
justified within TAN15 guidance.
8.4.2
The British Geology Survey (BGS) mapping data indicates that ground conditions are as
follows: ‐
1:50 000 Scale Bedrock Geology Description: Hollin Rock - Sandstone.
Sedimentary Bedrock formed approximately 309 to 310 million years ago in the
Carboniferous Period.
Setting: Swamps, Estuaries and Deltas.
These rocks were formed in marginal coastal plains with lakes and swamps
periodically inundated by the sea; or estuaries and deltas, and shallow seas.
1:50 000 Scale Superficial Deposits Description:
None Recorded.
8.4.3
The Cranfield Soil and Agrifood Institute Soilscapes soil type viewer identifies the soils as;
slowly permeable, seasonally wet, slightly acid but base-rich loamy and clayey soils. Drainage
is considered to be impeded, described as waterlogged in wet ground conditions. Drainage is
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to the local stream network and the main risks are associated with overland run-off from
adjacent agricultural fields (due to the high level of compactness).
8.4.4
Based on analysis of the online BGS and NSRI Soilscapes data, it can be considered that
infiltration drainage is not likely to provide a suitable means of surface water management
for the flows generated by the proposed development. However if infiltration is to be
considered as a suitable option then soakaway testing to BRE365 is advised in the locations
considered most feasible for infiltration within site.
8.5
Discharge via Watercourse
8.5.1
It is understood that an Ordinary watercourse is predominantly culverted through site with a
small open section along the south-western boundary and the eastern boundary. This
watercourse is understood to be a tributary of ‘Byr Brook’ which runs north-east
approximately 1.8km before converging with the River Alyn in Pontblyddyn. Pertinent
planning drawing suggest the watercourse feature will remain post-development as a formal
feature following removal of some of the culverted sections through site and re-profiling.
8.5.2
It is understood that the surface water run-off generated by the existing brownfield
development discharges to the watercourse which bisects the site, following a site walkover
which revealed the presences of gullies within the key areas of hardstanding.
8.5.3
There will be a decrease in the impermeable areas within site due to the proposals; it is
proposed that surface water run-off generated by the development be discharged to the
watercourse running through site. However, due to the nature and scale of the proposals
the run-off generated will be restricted when discharging to the watercourse, in order to
comply with the guidance set out in TAN15 (to minimise flood risk elsewhere within the
catchment).
8.5.4
Consents will be required from NRW and the LPA to discharge to the Ordinary Watercourse
and further reductions on the discharge rates may be required, therefore early discussion is
advised.
8.5.5
Surface water run-off generated by the proposed development is proposed to be restricted
to the pre-development rates of run off for various events, up to and including the 1 in 100
year event. Further betterment on these rates may be required following discussions with
the NRW and LPA, therefore early discussion is advised. Restricting the rate of surface water
discharge can be achieved using a flow control device such as a Hydrobrake® or similar
approved product.
8.5.6
The approximate pre-development run-off generated from the total site area is 58.1l/s for
the annual return period event, 129.9l/s for the 1 in 30 year return period storm event and
173.2l/s for the 1 in 100 year return period storm event with an allowance for climate
change.
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8.5.7
Restricting the rate of discharge for the surface water generates a storage requirement
during the extreme rainfall events. For the annual storm event storage requirements are
estimated to be between 0cu.m and 25cu.m, restricting the flows to 58.1l/s.
8.5.8
For the 1 in 30 year event storage is estimated to be between 11cu.m and 81cu.m, when
restricting the flows to 129.9l/s. A storage requirement of between 67cu.m and 182cu.m is
estimated, when flows are restricted to 173.2l/s, during the 100 year return period storm
event with an allowance of 30% for climate change (see Appendix L for details).
8.5.9
The stormwater storage figures quoted above are estimates only and the detailed drainage
design will determine with accuracy the stormwater storage requirements.
8.5.10 Any informal green space could be utilised as a multi-use area, incorporating SUDs designs,
to provide some of the required storage; catering for the extreme storm events up to and
including the 100 year return period events. Oversized pipes may be required in some areas
due to the uncertainties surrounding the existing topography of the area. Detailed design
will be required to confirm feasibility following further investigation.
8.6
Discharge via Sewer
8.6.1
Welsh Water records have identified a combined sewer network (150mm dia.) to run northeast along the A5104 (Corwen Road) south of the proposed development site. The nearest
manhole to site is identified on the records as being SJ26588902 (WW Ref.).
8.6.2
Irrespective, due to the close proximity of the identified watercourse, there are no proposals
to discharge the surface water run-off, generated by the proposed development, to the
public sewer network, as discharge via watercourse is considered a priority in the
hierarchical approach to the appropriate management of surface water run-off.
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9.0
FOUL WATER MANAGEMENT
9.1
Correspondence with Welsh Water (WW) has identified the location of an existing public
combined sewer system (150mm dia.) running north-east along the A5104, on the southern
boundary of site. The nearest manhole to site is identified on the records as being
SJ26588902 (WW Ref.).
9.2
A copy of the sewer records and correspondence is included in Appendix G.
9.3
At present it is unclear where the foul water flows generated by the existing development
within the proposed development site discharge to, it is understood that the flows discharge
to the adjacent combined sewer (150mm dia.) in ‘Corwen Road’. Further investigation is
advised to confirm outfall of the foul water flows generated by the existing development.
9.4
It is proposed that the foul water flows generated by the proposed development be
discharged to this public combined sewer system (150mm dia.) south of site. Potential
connection points include the unidentified connection point from the existing development
(providing the condition of such is acceptable), alternatively a connection direct to the
combined system (150mm dia.) via manhole SJ26588902 (WW Ref.) may be appropriate
following further investigations.
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10.0 SUMMARY AND CONCLUSIONS
10.1
This Flood Consequence Assessment has been prepared to support an outline planning
application for the construction of a residential development; complete with access road,
external works, footpaths, car parking, landscaping, boundary walls, fencing, external
services and drainage on land previously occupied by ‘Station Yard’ Coed-Talon.
10.2
The site is predominantly located within Flood Zone A, with the eastern boundary located
within Flood Zones B and C2 and the residential nature of the proposals means the site is
classified as ‘highly vulnerable’. The proposals would be considered ‘acceptable’ within
Flood Zone (A); providing all surface water management requirements are conformed to.
This nature of development would also be considered appropriate within Flood Zone B
providing appropriate mitigation measures were in place to secure the development for its
design life.
10.3
As the development site is currently brownfield it can be considered that the residential
proposals offer betterment on the existing situation and would be considered appropriate
providing the flood risk to site can be effectively managed. It would therefore be
recommended that an intra-sequential approach to flood management be adopted and
development be steered to areas at least risk.
10.4
The proposed development site is understood to be partially located within Flood Zone B
and C2 and the site is underlain by a ‘Secondary A’ Aquifer, influenced little by overland runoff due to the topography and influenced by surface water flooding in varying degrees of
severity due to the existing land-use.
10.5
It is considered that the majority of site would remain flood free during the design period
event (Q100+CCA event), following the review of the hydraulic model; due to sufficient
capacity within the existing culverts onsite. The water surface elevation varies through site
based on the location and proximity to the watercourse, however no out of channel flooding
is anticipated within site based on the simulations.
10.6
The existing Byr Brook culvert upstream of site is considered to have insufficient capacity to
cater with the extreme events, some out of channel flows would be anticipated upstream of
site, however any water exceeding the channel at this point would flow safely away from
site, utilising the existing drainage systems within Corwen Road, or conveying along the
highway, to the south of site.
10.7
The proposed removal of the culverts onsite and implementation of open channels would
have a positive effect on the water surface elevation for the upstream watercourses,
reducing the flood risk. No increase in flood risk would be anticipated downstream due to
the proposals based on the hydraulic assessment.
10.8
Although the extent of the flood zone is within the channel of the watercourses for the
100year return period event, mitigation measures are proposed in the form of Finished Floor
Levels (FFL) which is proposed a minimum of 600mm above the 1% AEP (1 in 100 year) event
FRA262 – FCA
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with an allowance for climate change. The proposed FFL will vary based on the location and
proximity to the watercourse; detailed design should account for this variation through site
and set FFL’s to reflect such.
10.9
Compensatory Flood Storage will not be required as no displacement of floodplain waters in
anticipated at this time.
10.10 Consultation with Natural Resources Wales identified one recorded historic flood event, in
2000, associated with the Unnamed Tributary within the site boundaries. It is understood
that the flooding occurred due to the presence of debris, fly-tipping upstream and the
presence of services pipes crossing the watercourse. No other historical flood incidents have
been identified, following removal of debris and relocation of the services pipes.
10.11 The development would be considered as accessible for emergency access and egress during
times of extreme flooding provided the proposed access/egress road culvert has sufficient
capacity and the channel is transformed to its natural state where possible; the maximum
acceptable inundation depths along the route should not exceed 600mm in accordance with
TAN15 which are to be confirmed during detailed design.
10.12 The FCA has reviewed all sources of flood risk to both the proposed development and to the
existing adjacent development as a result of the proposals, including; fluvial, tidal, pluvial,
groundwater, sewers and flooding from artificial sources.
10.13 Based on the ground conditions identified by the BGS and NSRI Soilscapes Data, it can be
considered that that infiltration is not likely to provide a feasible surface water management
solution, therefore it is proposed that surface water run-off, discharge to the watercourse
running through site. Surface water run-off rates will be restricted to the pre-development
rates of run off for various events, up to and including the 100 year return period event.
10.14 Restricting the rate of surface water run-off complies with the requirements of TAN15 and
generate a storage requirement during the extreme rainfall events. It is proposed that up to
and including the 100 year return period event with an allowance for climate change (30%)
be catered for on-site to comply with guidance in TAN15.
10.15 It is proposed that the foul water flows generated by the development discharge into the
combined sewer system (150mm dia.) located along Corwen Road, with an exact connection
point to be confirmed following site investigations, during the detailed design stage.
10.16 As with any drainage system blockages within either the foul or surface water sewer systems
have the potential to cause flooding or disruption.
10.17 This Flood Consequence Assessment is considered to be commensurate with the
development proposals and in summary, the development can be considered appropriate in
accordance with TAN15 and the mandatory requirements of the Code for Sustainable
Homes.
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11.0 RECOMMENDATIONS
11.1
Any overland flows generated by the proposed development must be directed away from
residential properties; safe avenues of overland flow must be considered in order to comply
with TAN15 guidance on not increasing localised flood risk downstream of new
developments.
11.2
With the proposals being ‘residential’ in nature, opportunities should be sought to provide
soft landscaping where at all possible, to assist in minimising surface water run-off onsite. It
is recommended that SuDS systems are considered within the development to manage
surface water run-off, however the exact measures will be determined at detailed design.
11.3
In order to mitigate for any potential future fluvial flooding, finished floor levels are
proposed to be set a minimum of 600mm above the 1% AEP +CCA event, the FFL is
estimated to vary based on the location and proximity to the watercourses crossing site and
therefore required to be confirmed during detailed design following review of a site layout.
11.4
Restricting the rate of surface water run-off complies with the requirements of TAN15 and
generate a storage requirement during the extreme rainfall events. For the annual storm
event storage requirements are estimated to be between 0 and 25cu.m, restricting the flows
to 58.1l/s. A storage requirement of between 67 and 182cu.m is estimated, when flows are
restricted to 173.2l/s, during the 100 year return period storm event with an allowance of
30% for climate change.
11.5
The proposed onsite surface water drainage system will need to be sized to cater for storm
events up to and including the 100 year return period storm event with a 30% allowance for
climate change.
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Bibliography & References
CIRIA 522: Sustainable urban drainage systems – design manual for England and Wales (2000).
CIRIA 523: Sustainable urban drainage systems – best practice manual (2001).
CIRIA 609: Sustainable drainage systems. Hydraulic, structural and water quality advice (2004).
CIRIA 624: Development and flood risk – guidance for the construction industry (2004).
CIRIA 635: Designing for exceedance in urban drainage: Good practice (2006).
CIRIA 644: Building Greener (2007).
CIRIA 697: The SUDS manual (2007).
Climate Change Wales Learning to Live Differently (2002).
Flood Risk to People – Phase 2 (FD2321/TR2), DEFRA and the Natural Resources Wales (2006).
Flood estimation for small catchments: Institute of Hydrology Report No.124, NERC (1994).
Flood Estimation Handbook, Centre for Ecology and Hydrology (1999).
Interim Code of Practice for Sustainable Drainage Systems (2004),
Planning Policy Wales (2002).
Sewers for Adoption 7th Edition, WRc (2012).
Technical Advice Note 15: Development and Flood Risk (2006).
Joint DEFRA/EA Flood & Coastal Erosion Risk Management - Preliminary rainfall runoff management
for developments: Technical Report W5-074/A/TR/1 Rev.E (2012)
Web-Based References
Bingmaps – http://www.bing.com/Maps/
British Geological Survey – http://www.bgs.ac.uk/opengeoscience/home.html
Canal & River Trust – http://canalrivertrust.org.uk/canals-and-rivers/
Chronology of British Hydrological Events – www.dundee.ac.uk/
CIRIA – http://www.ciria.org/
Cranfield University – http://www.landis.org.uk/soilscapes/
Environment Agency – www.environment‐agency.gov.uk/
Flintshire County Council – http://www.flintshire.gov.uk/en/Resident/
FloodProBE – http://www.floodprobe.eu/
Flood Forum – http://www.floodforum.org.uk/
Flood London – http://www.floodlondon.com/
Flood Resilience Group – http://www.floodresiliencegroup.org/frg/
Google Maps – http://maps.google.co.uk/
London Resilience – http://www.londonprepared.gov.uk/
Shire Group of IDB’s – http://www.shiregroup‐idbs.gov.uk/default.asp
Streetmap – http://www.streetmap.co.uk/
US Army Corps of Engineers – http://www.hec.usace.army.mil/software/hec‐ras/
Watertight International – http://www.watertightinternational.com/
Welsh Water Wastewater Developer Services - http://www.dwrcymru.com/en/
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APPENDIX A:
TAN15 COMPLIENCE LIST
FRA262 – FCA
FRA262 - Compliance List for TAN 15
ITEM
REQUIRED ASSESSMENT
(TAN15)
SUMMARY OF FINDINGS
1
The likely mechanisms of
flooding
Site located predominantly within Flood Zone A on the DAM, with a small
portion on the south-eastern boundary to be located within Flood Zones B
and C2.
5.0
The likely sources of
flooding
•
•
•
•
•
•
5.0
2
Fluvial/Tidal
Groundwater
Artificial Sources of Flooding
Surface Water Flooding
Overland Run-off
Sewer Flooding
Correspondence with Natural Resources Wales indicated that there is no
model or flood defence information for the proposed development site;
therefore the potential depths of flood waters within site cannot be
accurately ascertained.
3
The depths of flooding
throughout the site
Hydraulic modelling undertaken by Betts Associates would indicate that the
whole site lies within the extents of Flood Zone A with the Flood Zones B and
C being confined to the watercourse channels.
REPORT
SECTION
5.0
Appendix G
5.4
Estimates for surface water flooding can be obtained from the EA online
mapping information and this data has been reviewed within the FCA report.
4
5
6
The rate of rise of
floodwaters through site
Velocities of floodwaters
across site
Overland flood routes
It is however understood that water would be confined to the lower
elevations within site which are predominantly open space and recreational
areas based on pertinent planning drawings.
2.3
5.0
5.0
The EA online mapping website indicates approximate estimates for surface
water flooding in the identified areas at risk within site, this data has been
reviewed within the FCA report.
Review of the detailed topographical survey for the site indicated the current
understanding of the natural topography; this results in there being little
likelihood of significant flows impacting on the proposed development or on
adjacent land and property, as flows flow away from site via the adjacent
watercourse.
Overland flows generated must be carefully controlled and safe avenues away
from development sought after.
2.3
5.1
Appendix O
The proposed access road to site would require to cross the proposed open
channel watercourse through site, this will require a short length of culvert or
ideally a bridge deck. This proposed culvert should be sized sufficiently to
cater for the extreme events up to and including the 1000yr event.
7
The effects on access and
egress and infrastructure
The existing culvert size is 1850mm (downstream) and in order to future proof
the capacity, the proposed culvert would need to be 2.1m (dia.); this has been
modelled and determined adequate. Alternatively to improve the channel
morphology it may be preferred that a bridge deck be constructed over the
open channel however this will again be required to be confirmed during
detailed design.
2.4
5.6
The majority of site comprises large areas of hardstanding, and salvage
related materials, current land use would suggest a high potential for
contamination and leaching into the natural environment. The proposed
residential development would significantly reduce this contamination risk.
8
The impacts of the
development on natural
heritage
Added biodiversity would be gained from the opening of the existing
culverted watercourse through site and by incorporating SuDS into the
surface water management strategy water quality of this Ordinary
Watercourse would be significantly improved due to the development
proposals.
5.6
7.0
No statutorily designated nature conservation sites have been identified as
being within 1km of the site from the preparation of this report.
Mitigation measures have been suggested to reduce the associated risks from
a variety of flooding sources to and from the development proposals.
9
The impact of the
development in terms of
flood risk on
neighbouring properties
and elsewhere on the
floodplain
The surface water run‐off generated will be managed effectively, with the
peak rates of run‐off being restricted to the equivalent of the pre‐
development situation; minimising the associated flood risk downstream.
In order to mitigate the fluvial flood risk to the residential dwellings, Finished
Floor Levels are proposed, set a minimum of 600mm above the 1% AEP (1 in
100 year) event with an allowance for climate change.
When raising levels within Flood Zone C, compensatory flood storage (onsite)
is required to cater for the displacement of the flood waters; No displacement
of floodplain is proposed therefore no compensatory storage is required.
5.0
8.0
FRA262 – FCA
APPENDIX B:
TECHNICAL REQUIREMENTS FOR TAN15
FRA262 – FCA
FRA262 - Technical Requirements of TAN 15
ITEM
REQUIREMENT
1
Location Plan
2
A plan showing
existing levels related
to Ordnance Datum.
3
More detailed
indication of flood
alleviation measures.
4
Assessment of
potential sources of
flooding.
6
A plan of site
showing flood
predictions.
Description of
structures influencing
the local hydraulics.
SUMMARY
REPORT
SECTION
*
Included in appendices, with Aerial images of the site and
surrounding area included throughout the FCA.
Section 2.1
Appendix C
*
An outline description of topography within site is provided, with
an aerial image indication general fall within site, based on
reviewed mapping data and observations following a site visit; as
a detailed topographical survey is not yet available for the site.
Section 2.3
Appendix D
A detailed Mitigation and Residual Risks section is provided
within the report which examines the key flood risk issues
discussed within the FCA.
A detailed description is given on access and egress during times
of emergency. All future residents are proposed to be advised of
the importance of emergency planning and understanding
evacuation routes.
A plan showing
accesses/evacuation
routes.
5
7
MINIMUM
INCLUSION
Guidance is given within the report for referral to the national
‘Ready for Flooding’ advise booklet along with the EA free flood
warning service for the area (Floodline Warnings Direct) which
should increase the communities resilience to flooding.
*
Section 5.6
Section 2.4
Site located within Flood Zones A, B C2 with reference to the
DAM: considered to be at varying risk from:
o Fluvial/Tidal
o Groundwater
o Artificial Sources of Flooding
o Surface Water Flooding
o Overland Run-off
o Sewer Flooding
Section 5.0
Overland Flood Flow Routing Plan only included; as detailed
model data is not available from NRW (following
correspondence).
Appendix O
Hydraulic modelling undertaken by Betts Associates would
indicate that the whole site lies within the extents of Flood Zone
A with the Flood Zones B and C being confined to the
watercourse channels.
Appendix G
A detailed description of the existing structures onsite is giving
within the report and all existing structures have been evaluated
as part of the hydraulic model.
The site is lies predominantly within Flood Zone A according to
the DAM; with the south and eastern boundaries of site to be
located within Flood Zone B and C.
8
Assessment of
probabilities.
The site is underlain by a ‘Secondary A’ Aquifer, influenced little
by overland run-off due to the topography and influenced by
surface water flooding in varying degrees of severity based on key
rainfall events.
The identified fluvial flood risk to site (Flood Zone C extents) is
Section 5.0
understood to be due to the existing culverted section of ‘Byr
Brook’ being inadequately sized to cater for the 1000 year return
period storm event.
Proposals to open the channel through site and have a short
length of culvert (beneath the access road) sized sufficiently, to
cater for the 1000 year event should adequately mitigate any
fluvial flood risk for the extreme events.
9
10
11
Cross-section of site
including FFL/road
levels.
*
Minimum finished floor levels for the site are proposed a
minimum of 600mm above the 1% AEP (1 in 100 year) event with
an allowance for climate change, to safe guard the development
for its design life (100 years).
Assessment of flood
speeds.
Section 5.1
Section 5.4
The EA online mapping website indicates approximate estimates
for surface water flooding in the identified areas at risk within
site, this data has been reviewed within the FCA report.
Assessment of
drains/sewer
hydraulics.
Correspondence with a variety of parties has identified no
historic/existing risks to the proposed development site.
Section 5.4
Section 8.0
Appendix G
Site is predominantly located within Flood Zone A (DAM), which is
where the majority of the proposed residential dwellings will be
constructed.
12
Assessment of
displaced water and
run-off volumes.
*
watercourse channels. No Displacement of floodplain is
anticipated as part of the proposals.
Surface water run-off has been calculated both pre and post
development and proposals are to restrict post-development runoff to the predevelopment situation (calculations have been
included within the report and appendices). The required storage
for the extreme storm events following restriction of discharge
rates is calculated within the report and has been considered
within the surface water management strategy.
Section 5.4
Section 8.0
Appendix K &
L
The requirement for storage within site due to any displacement
of floodplain waters has been discussed within the body of the
report. No displacement of floodplain is anticipated as part of the
proposals and therefore no compensatory storage is required.
Section 5.4
Section 8.0
13
Assessment of
impact of displaced
water.
14
Assessment of
impact on
fluvial/coastal
morphology.
The existing culverted Ordinary Watercourse running through site
is proposed to be opened up and a formal watercourse feature
through site. This will improve the morphology of this section of
the tributary and potentially increase the capacity of the system,
reducing the historic flood risk (identified to be due to poor
culvert condition and capacity.
Section 5.0
15
Considerations for
uncertainties in
future flood
estimations.
Climate Change allowance of 30% peak rainfall intensity
incorporated into surface water management in compliance with
the guidance in TAN15.
Section 6.0
Section 8.0
16
Assessment of
residual risks
(following
construction of
defences).
*
*
There are no identified structures within the vicinity of the
proposed development site following correspondence with
Natural Resources Wales.
Residual risks have been discussed within the report along with
an indication of required mitigation measure for the development
proposals.
Section 5.6
Appendix G
Site is predominantly located within Flood Zone A, with a small
portion located within Flood Zones B and C2 according to the
DAM.
17
Summary of flood
sources, how it might
develop, impact
elsewhere and
specific conditions.
*
The site is considered to be at varying risk from:
o Fluvial/Tidal
o Groundwater
o Artificial Sources of Flooding
o Surface Water Flooding
o Overland Run-off
o Sewer Flooding
All potential flood sources to and from the development
proposals have been reviewed within the FCA. Appropriate
mitigation measures are proposed to safeguard the development
for its design life.
Surface water management has been considered within the FCA
with estimates of rate and volumes quoted. Approximate storage
volumes are also provide for post-development due to restricting
the discharge from site to the pre-development situation.
A full summary is included in the report.
Section 5.0
Section 10.0
APPENDIX C:
LOCATION PLAN
FRA262 – FCA
Location Plan
Station Yard, Corwen Road, Coed-Talon, CH7 4TN
OS X (Eastings)
OS Y (Northings)
Nearest Post Code
Lat (WGS84)
Long (WGS84)
LR
mX
mY
326810
358901
CH7 4TN
N53:07:20 (53.122237)
W3:05:42 (-3.095123)
SJ268589
-344547
6971436
APPENDIX D:
TOPOGRAPHIC SURVEY
FRA262 – FCA
APPENDIX E:
WELSH GOVERNMENT DEVELOPMENT ADVICE MAP (DAM)
FRA262 – FCA
APPENDIX F:
NRW/EA INFORMATION & CORRESPONDENCE
FRA262 – FCA
Kirsty Williams
From:
Sent:
To:
Cc:
Subject:
Attachments:
Kirsty Williams
15 May 2014 15:35
Natural Resources Wales ([email protected])
'[email protected]'
Location Plan.pdf
To whom it may concern, Station Yard, Corwen Road, Coed-Talon, CH7 4TN
Please could you confirm whether you have any information that you feel would be valuable to a Flood Consequence Assessment for the above site (location plan attached), including details of historical flooding; this would be greatly appreciated. Please do not hesitate to contact me on the details below to discuss further should you require additional information or clarification. Kind regards Kirsty Williams Graduate Flood Risk Analyst Betts Associates Ltd Old Marsh Farm Barns, Welsh Road, Sealand, Flintshire, CH5 2LY T ‐ 01244 288178 F ‐ 01244 288516 kirstywilliams@betts‐associates.co.uk www.betts‐associates.co.uk CIVIL | STRUCTURAL | GEO‐ENVIRONMENTAL | TECHNICAL DUE DILIGENCE FLOOD RISK MANAGEMENT | STRUCTURAL SURVEYS | PARTY WALL DUTIES | ECOLOGY ELECTRONICALLY TRANSMITTED INFORMATION This electronic transmission is strictly confidential and intended solely for the addressee. It may contain information which is covered by legal, professional or other privilege. If you are not the intended addressee, you must not disclose, copy or take any action in reliance of this transmission. If you have received this transmission in error, please notify us as soon as possible. All emails transmitted by Betts Associates are virus checked. This does not guarantee that transmissions are virus free. Reference should always be made to the hard copy of any electronically transmitted files. Electronic data does not constitute contract documentation. Use of the content of our files is at your own risk. You remain responsible for anything produced using all or part of the data supplied. 1
Kirsty Williams
From:
Sent:
To:
Subject:
Attachments:
Access to Information Team
<[email protected]>
10 June 2014 15:57
Kirsty Williams
ATI-04473A
NRW VAT Receipt ati-04473a.docx; ati-04473 vat.doc; Standard_Notice.pdf
Good Afternoon Kirsty,
We have collated data for ATI‐04473a – Station Yard, Corwen Road, Coed‐Talon, CH7 4TN
The data are:

Flood Map for Surface Water 1 in 30, 100, 1000 yearly event

Historic Flood Event Outline information

Fluvial Flood Zones Map
Unfortunately we can’t provide model information for this site or flood defence information (as there are no formal defences at the site).
Can you please let us know if the customer is still interested in receiving this information, and can you please contact our customer service centre on 0300 065 3000 top make payment.
Kind Regards
Gareth Cryer
Access to information team 1
Flood Event Outline at 326826.358978
Legend
Un-named trib of Black Brook Oct 2000
Flood Event Outline
Un-named trib of Black Brook at
Pontybodkin, October 2000
Flood Event Group ID: 1000002000001
5 properties were flooded and the flood
event lasted 1 day.
Cause of flooding unknown.
0 25 50
100 Meters
¯
Reproduced by permission of Ordnance Survey on behalf of HMSO.
© Crown Copyright and database right 2013. Ordnance Survey
licence number 100019741.
Atgynhyrchwyd â chaniatâd yr Arolwg Ordnans ar ran Llyfrfa ei
Mawrhydi. © Hawlfraint a hawliau cronfa ddata’r Goron 2013.
Rhif Trwydded yr Arolwg Ordnans 100019741.
Fluvial Flood Zones at 326826.358978
Legend
Fluvial Flood Zone 3
Fluvial Flood Zone 2
Flood Zone 3 indicates
the area that could be flooded
with a 1% (1 in 100), fluvial
and 0.5% (1 in 200) tidal, or
greater chance of happening
each year.
Flood Zone 2 indicates
the extent of an extreme flood
from a river and/or the
sea. These areas are likely
to be affected by a major flood,
with up to a 0.1% (1 in 1000)
chance of occurring each year.
Flood Zones do not provide
information on flooding from
groundwater or other sources
0 25 50
100 Meters
¯
Reproduced by permission of Ordnance Survey on behalf of HMSO.
© Crown Copyright and database right 2013. Ordnance Survey
licence number 100019741.
Atgynhyrchwyd â chaniatâd yr Arolwg Ordnans ar ran Llyfrfa ei
Mawrhydi. © Hawlfraint a hawliau cronfa ddata’r Goron 2013.
Rhif Trwydded yr Arolwg Ordnans 100019741.
Flood Map for Surface Water 1 in 30
Legend
0
33
66
99 m.
© Environment Agency copyright and / or database rights 2014. All rights reserved. Reproduced by permission of Ordnance Survey on behalf of HMSO. © Crown Copyright and database right 2014. Ordnance Survey licence number 100024198.
Legend
0
33
66
99 m.
Legend
0
33
66
99 m.
Enter a postcode or place name:
Other topics for this area...
Risk of Flooding from Rivers and Sea
View other Interactive Maps
Risk of Flooding from Rivers and Sea
River flooding happens when a river cannot cope with the amount of water draining into it from the surrounding land. Sea flooding
happens when there are high tides and stormy conditions.
The shading on the map shows the risk of flooding from rivers and the sea in this particular area.
Click on the map for a more detailed explanation.
Map of Pontybodkin, Flintshire at scale 1:10,000
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Risk of Flooding from
Rivers and Sea
High
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328035, 359095
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© Environment Agency 2014
Author: The Environment Agency | [email protected]
Last updated: 06 June 2014
Interactive Maps
Risk of Flooding from Riv ers and Sea for X:326854, Y:359081
The location you have selected is in an area that has a very low chance of flooding from rivers or the sea.
What does ‘very low ’ mean?
Very low means that each year, this area has a chance of flooding of less than 1 in 1000 (0.1%).
This takes into account the effect of any flood defences that may be in this area. Flood defences reduce, but do not
completely stop the chance of flooding as they can be overtopped or fail.
Floods Destroy. Be prepared
It is important to remember that while the risk is low, we can never eliminate all flooding. Surrounding roads and
services may still be affected and could impact you.
Check if you can receive free flood warnings
Complete a flood plan
Find out how to prepare your property for flooding
Planning a development
This information is not suitable for use in land-use planning. If you are planning a development, you need to use the
Risk of Flooding for Land-Use Planning (Rivers and Sea) for England or Development Advisory Map for Wales. This
is because for planning purposes you need to use information based on flooding without defences.
Further information
You can also check the level and flow estimates for rivers and sea, and the latest river and sea levels.
If you have questions about how the map was produced, please call Floodline on 0845 988 1188.
This area may be at risk from other types of flooding.
Check your risk of flooding from surface water.
Check your risk of flooding from reservoirs.
For the purposes of the Flood Risk Regulations 2009 and the EU Directive 2007/60/EC on the assessment and
management of flood risks, this is a Flood Hazard Map
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Risk of Flooding from Reservoirs
Risk of Flooding from Reservoirs
Reservoir flooding is extremely unlikely to happen.
The shading on the map shows the area that could be flooded if a large reservoir were to fail and release the water it holds. A large
reservoir is one that holds over 25,000 cubic metres of water, equivalent to approximately 10 Olympic sized swimming pools.
Since this is a worst case scenario, it’s unlikely that any actual flood would be this large.
Click on the shading to see details of reservoirs that could cause flooding in this area.
Map of X: 326,776; Y: 358,941 at scale 1:10,000
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Maximum extent of
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Risk of Flooding from Surface Water
Risk of Flooding from Surface Water
Surface water flooding happens when rainwater does not drain away through the normal drainage systems or soak into the ground,
but lies on or flows over the ground instead.
The shading on the map shows the risk of flooding from surface water in this particular area.
Click on the map for a more detailed explanation.
Map of X: 326,776; Y: 358,941 at scale 1:10,000
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Risk of Flooding from Surface Water for X:326875, Y:359056
The location you have selected is in an area that has a very low chance of flooding from surface water.
What does 'very low ' mean?
Very low means that each year, this area has a chance of flooding of less than 1 in 1000 (0.1%).
This type of flooding can be difficult to predict, much more so than river or sea flooding as it is hard to forecast
exactly where or how much rain will fall in any storm.
This is based on the best information we have available, such as ground levels and drainage.
Floods Destroy. Be prepared
Don’t wait until it’s too late. Prepare for flooding by taking some simple steps to reduce the impact on your home or
business.
Complete a flood plan
Find out how to prepare your property for flooding
Check the three-day flood risk forecast
Further Information
The map has been produced by the Environment Agency, using information from Lead Local Flood Authorities
where it is available. Lead Local Flood Authorities are responsible for managing the risk from surface water flooding.
If you have questions about how the map was produced, please call Floodline on 0845 988 1188.
If you would like more information on how surface water is being managed in this area, you can speak to Flintshire
County Council.
You can use the information in this area to see the areas that would flood, which streets may be at risk of flooding,
and get an idea of the approximate depth of flooding.
The potential impact of surface water flooding can vary according to the depth of the water, and its velocity (speed
and direction that it is flowing in).
This area may be at risk from other types of flooding.
Check your risk of flooding from rivers and sea.
Check your risk of flooding from reservoirs.
For the purposes of the Flood Risk Regulations 2009 and the EU Directive 2007/60/EC on the assessment and
management of flood risks, this is a Flood Hazard Map.
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Environment Agency - What's in your backyard?
CH7 4TN
Map legend
Page 1 of 2
Groundwater
CH7 4TN at scale 1:75,000
Groundwater

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Text only version
Groundwater source
protection zones
Inner zone
(Zone 1)
Outer zone
(Zone 2)
Total catchment
(Zone 3)
Special interest
(Zone 4)

Aquifer Maps Superficial Deposits
Designation
Principal
Secondary A
Secondary B
Secondary
(undifferentiated)
Unknown (lakes and
landslip)

Aquifer Maps - Bedrock
Designation
Principal
Secondary A
Secondary B
Secondary
(undifferentiated)
Groundwater
Vulnerability Zones
Major Aquifer High
Major Aquifer
Intermediate
Major Aquifer Low
Customers in Wales - From 1 April 2013 Natural Resources Wales (NRW) has taken over the responsibilities of the Environment Agency in Wales.
More about Groundwater
British Geological Survey Aquifer data:
The Aquifer Extents are not displayed at scales greater than 1:75,000 (Ordnance Survey 1:250,000 scale) as the data
was only modelled to this level and is not accurate pass this.
Minor Aquifer High
Minor Aquifer
Intermediate
Minor Aquifer Low
New BGS Aquifer Designation Maps
From 1st April 2010 new aquifer designations replace the old system of classifying aquifers as Major, Minor and NonAquifer. This new system is in line with our Groundwater Protection Policy (GP3) and the Water Framework Directive
(WFD) and is based on British Geological Survey mapping.
Groundwater Source Protection Zones data:
The Source Protection Zones are not displayed at scales greater than 1:20,000 (Ordnance Survey 1:50,000 scale) as
the data was only modelled to this level and is not accurate pass this. They should not be compared against field
boundaries.
Groundwater Source Protection Zones
Groundwater provides a third of our drinking water. We ensure that your water is safe to drink defining Source
Protection Zones. These zones help to monitor the risk of contamination from any activities that might cause pollution
in the area.
Facts and figures of our groundwater resources
Find out more about groundwater and groundwater levels.
http://maps.environment-agency.gov.uk/wiyby/wiybyController?value=ch74tn&lang=... 25/06/2014
Environment Agency - What's in your backyard?
CH7 4TN
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Flood Warning Areas
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Areas where we issue
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
River level monitoring
(hi-flows)
River level monitoring (hiflows)

River and Sea levels
River and Sea levels
Customers in Wales - From 1 April 2013 Natural Resources Wales (NRW) has taken over the responsibilities of the Environment Agency in Wales.
More about Flood Warnings:
Flood Warning Areas
If your home or business is within a purple shaded area on the map then you can receive free flood warnings. We
issue flood warnings to specific areas when flooding is expected. If you receive a flood warning you should take
immediate action.
For further information visit our Flood warning pages.
Flood Alert Areas
If your home or business is within a pink shaded area on the map then you can receive free flood alerts. We issue
flood alerts when flooding is possible. In many areas we issue flood alerts for flooding from rivers, the sea and
groundwater. If you receive a flood alert you should be prepared for flooding and to take action.
It is very difficult to predict the exact location of flooding from groundwater as it is often related to local geology. We
can’t say for definite which properties are at risk from groundwater flooding. To help people we provide flood alerts for
large areas that could be affected if groundwater levels were high.
For further information visit our Flood warning pages.
River Levels
River level monitoring sensors are placed in the waters at key points and measure changes in water level. This data
is recorded at 15 minute intervals; it's then sent back to our offices to be published online at least once a day. The
information may be updated more frequently to meet operational needs, for example when water levels are high. This
is the most up to date information available about river and sea levels.
For further information visit our River and Sea Levels pages.
HiFlows
HiFlows-UK provides data on the flood peaks at around 1000 river flow gauging stations in the UK, for use in the flood
estimation methods.
For further information visit our HiFlows-UK pages.
http://maps.environment-agency.gov.uk/wiyby/wiybyController?value=CH7+4TN&la... 25/06/2014
Mr Christopher Kay - Director of Planning Ein cyf/Our ref: NT/2014/115599/05-L01
Eich cyf/Your ref: 051831
County Hall
Mold
Dyddiad/Date:
18 August 2014
Flintshire
CH7 6NF
Annwyl Mr Kay / Dear Mr Kay
OUTLINE - RESIDENTIAL DEVELOPMENT
MOLD, FLINTSHIRE
STATION YARD, COED TALON,
Thank you for referring the above application, which was received on 28 July 2014.
Justification Test
The site is partially within Zone C2 as per the Development Advice Map (DAM)
accompanying TAN15. This map is published by the Welsh Government and was
introduced with the TAN in 2004 and updated in 2009, with the current version
updated 2013. Your Authority will be aware of the Welsh Government letter of 9
January 2014 to Chief Planning Officers, reiterating that proposed highly vulnerable
development should not be permitted in Zone C2. Please refer also to a letter issued
by Welsh Government in January 2014 which reinforces national planning policy on
flood risk, available at: http://wales.gov.uk/topics/planning/developcontrol/decisionsmade-by-the-minister/?lang=en.
The submitted Flood Consequences Assessment (FCA) fails to establish that the
risks and consequences of flooding can be acceptably managed in line with TAN 15
Development & Flood Risk (2004) and therefore we maintain our OBJECTION to
this development.
www.cyfoethnaturiolcymru.gov.uk
www.naturalresourceswales.gov.uk
Llwyn Brain
FFordd Penlan
Parc Menai
Bangor
Gwynedd
LL57 4DE
Croesewir gohebiaeth yn y Gymraeg a'r Saesneg
Correspondence welcomed in Welsh and English
The submitted FCA (Betts Associates, July 2014) presents little evidence to support
its assertions, many of which are suitably aspirational but require further work in
order to demonstrate that they are achievable. The inclusion in the FCA of verbatim
tranches of publicly available policy is unnecessary; ditto references to the Flintshire
Unitary Development Plan which does nothing to support the case for compliance
with TAN 15. There are multiple instances where the same information is repeated
almost paragraph for paragraph in succeeding sections. In such a document, there is
always the risk that important information is overlooked and therefore we
recommend that all extraneous material in the FCA is removed and that it is rewritten
succinctly.
Finished floor level
For example, the FCA asserts in the Executive Summary and in paragraphs 5.6.6,
5.6.18 and 10.11 that finished floor levels can be set 600mm above the 1% AEP plus
climate change event, but there is no information on what this level might be and so
nothing to demonstrate that it is achievable.
Culverted watercourse
The submitted ‘Sketch viability layout’, reproduced in the FCA as ‘Figure 3 Planning
Layout Extract’, does not indicate where Byr Brook enters the site from the south or
show where the confluence of the newly opened up watercourses would be, and
seems to show only the unnamed tributary entering the site from the southwest and
the Byr Brook downstream of this.
No evidence is provided supporting the assertion that fluvial flood risk to the site is
due to lack of culvert capacity, or that opening up ‘the culvert’ (watercourse
unspecified) would ‘effectively mitigate the flood risk for the extreme flood events up
to and including the 1000 year event.’
No evidence is provided to support the proposed new access road culvert
dimensions. The FCA does not mention the proposed second culvert shown on the
layout, on the unnamed tributary of Byr Brook upstream of the main access road to
the site. No information is provided regarding the risk of blockage where Byr Brook
itself is culverted upstream (south) of the site, or how flood flows from such a
blockage could affect the site.
Flood Warning
Contrary to statements in the FCA, the site is not in a Flood Warning area. It is
indeed eligible to receive Flood Alerts, however these relate to the wider catchment
and not the watercourses which may affect this site.
Updated information
As per our previous response we recommend that the FCA supporting this
application should be updated to reflect:
·
improved modelling techniques;
·
changes to hydrology for the watercourses at the site;
·
an assessment of fluvial flood risk which includes climate change for the
lifetime of the development (up to the 0.1% event, as per the Welsh Government
2
letter to Chief Planning Officers of 9 January 2014);
·
mitigation measures required to ensure the development is flood free during
the 1% AEP plus climate change event;
·
any effects on flood risk elsewhere – if compensatory flood storage is
required, it should be demonstrated that it is feasible to provide it on a level for level
basis;
·
how safe access and egress to and from the development would be provided
(i.e the FCA should consider access and egress in the 0.1% plus climate change
event against all four thresholds in A1.15 of TAN 15).
This has not been done, therefore the FCA is incomplete.
Note that we reserve comment on surface water management until the above has
been addressed.
Yn gywir / Yours faithfully
MISS RUTH PRICHARD
Planning Liaison Officer/Swyddog Cydlynu Cynllunio
Direct dial 01248 48 4067
Direct fax 01248 670561
Direct e-mail [email protected]
3
APPENDIX G: WELSH WATER CORRESPONDENCE & RECORDS
FRA262 – FCA
Kirsty Williams
From:
Sent:
To:
Cc:
Subject:
Attachments:
Kirsty Williams
15 May 2014 15:46
Welsh Water - Flintshire, Wrexham ([email protected])
'[email protected]'
Location Plan.pdf
Good Afternoon Miriam, Station Yard, Corwen Road, Coed-Talon, CH7 4TN
Kirsty Williams
From:
Sent:
To:
Subject:
Wasik-Evans Miriam <[email protected]>
24 June 2014 11:38
Kirsty Williams
RE: Station Yard, Corwen Road, Coed-Talon, CH7 4TN
Kirsty, We do not have any records of historic flooding within the vicinity of the site. Regards, Miriam Wasik‐Evans Development Control Officer | Developer Services | Dwr Cymru Welsh Water PO Box 3146 | Cardiff | CF30 0EH | T: 0800 917 2652 | F: 02920 740472 | Ext. 26755 From: Kirsty Williams [mailto:[email protected]]
Sent: 09 June 2014 16:05
To: Evans Miriam
Cc: Richard Nicholas
Subject: Station Yard, Corwen Road, Coed-Talon, CH7 4TN
Good Afternoon Miriam, I am just following up on an email sent out 15.05.14 regarding flood risk at a site in Coed‐Talon (see below), I am aware of the required waiting time for a response however I have not yet received any correspondence back from yourself, could you confirm whether an email has been received/replied to with regards to the site: Station Yard, Corwen Road, Coed‐Talon, CH7 4TN (Please could you confirm whether you have any information that you feel would be valuable to a Flood Consequence Assessment for the above site (location plan attached), including details of historical flooding; this would be greatly appreciated). Kind Regards Kirsty Williams Graduate Flood Risk Analyst Betts Associates Ltd Old Marsh Farm Barns, Welsh Road, Sealand, Flintshire, CH5 2LY T ‐ 01244 288178 F ‐ 01244 288516 kirstywilliams@betts‐associates.co.uk www.betts‐associates.co.uk CIVIL | STRUCTURAL | GEO‐ENVIRONMENTAL | TECHNICAL DUE DILIGENCE FLOOD RISK MANAGEMENT | STRUCTURAL SURVEYS | PARTY WALL DUTIES | ECOLOGY ELECTRONICALLY TRANSMITTED INFORMATION This electronic transmission is strictly confidential and intended solely for the addressee. It may contain information which is covered by legal, professional or other privilege. If you are not the intended addressee, you must not disclose, copy or take any action in reliance of this transmission. If you have received this transmission in error, please notify us as soon as possible. All emails transmitted by Betts Associates are virus checked. This does not guarantee that 1
APPENDIX H: FLINTSHIRE COUNTY COUNCIL CORRESPONDENCE
FRA262 – FCA
Kirsty Williams
From:
Sent:
To:
Cc:
Subject:
Attachments:
Kirsty Williams
15 May 2014 15:47
'[email protected]'
'[email protected]'
Location Plan.pdf
Good Afternoon Ruairi, Station Yard, Corwen Road, Coed-Talon, CH7 4TN
Kirsty Williams
From:
Sent:
To:
Subject:
[email protected]
05 June 2014 18:21
Kirsty Williams
Re: Station Yard, Corwen Road, Coed-Talon, CH7 4TN
Hi Kirsty, Late reply I'm afraid. We have no formal records on file here of flooding at the location indicated. Regards Ruairí Ruairí Barry ____________________________________________________________________________________ Project Engineer | Peiriannydd Prosiec Engineering Services | Gwasanaethau Peirianneg Environment | Amgylchedd Flintshire County Council | Cyngor Sir y Fflint ____________________________________________________________________________________ Tel | Ffôn | 01352 704707 Email | Ebost | [email protected] ____________________________________________________________________________________ http://www.flintshire.gov.uk | http://www.siryfflint.gov.uk http://www.twitter.com/flintshirecc | http://www.twitter.com/csyfflint From: Kirsty Williams <kirstywilliams@betts‐associates.co.uk> To: "[email protected]" <[email protected]>, Cc: Richard Nicholas <richardnicholas@betts‐associates.co.uk> Date: 15/05/2014 15:47 Subject:Station Yard, Corwen Road, Coed‐Talon, CH7 4TN Good Afternoon Ruairi, Station Yard, Corwen Road, Coed‐Talon, CH7 4TN Please could you confirm whether you have any information that you feel would be valuable to a Flood Consequence Assessment for the above site (location plan attached), including details of historical flooding; this would be greatly appreciated. Please do not hesitate to contact me on the details below to discuss further should you require additional information or clarification. Kind regards Kirsty Williams Graduate Flood Risk Analyst 1
FRA262 – FCA
APPENDIX I:
TAN15 EXTRACTS
FRA262 – FCA
APPENDIX J:
FEH CATCHMENT DATA & DESCRIPTORS
FRA262 – FCA
65
500m
500m
67
66
Hawarden
500m
65
Pant-y-mwyn
Drury
64
500m
64
Mold Mynydd Isa Buckley
63
62
500m
63
Llong
Gwernymynydd
500m
500m
Maeshafn
61
Nercwys
60
500m
Leeswood
500m
60
500m
Coed Talon
59
Treuddyn
Eryrys
500m
500m
58
Caergwrle
57
Llanfynydd
500m
59
Hope
500m
58
500m
61
Pontblyddyn
Llanferres
500m
62
Penyffordd
Tafarn-y-Gelyn
500m
500m
57
Abermorddu
500m
Llanarmon-yn-lal
56
56
Ffrith
500m
55
Rhydtalog
500m
54
500m
53
51
500m
53
500m
Tan-y-fron
Minera
500m
54
Gwersyllt
Gwynfryn
Pen-y-stryt
500m
Summer Hill
Bwlchgwyn
52
55
Windy Hill
500m
500m
Coedpoeth
52
500m
New Broughton
51
500m
500m
50
50
500m
500m
49
49
Rhostyllen
500m
500m
48
48
Hafod-y-bwch
500m
47
Pentredwr
500m
3
500m
68
500m
New Brighton
500m
70 000m
69
Pentre
Mancot
Soughton
Llyn-y-pandy
500m
3
Printed from FEH CD-ROM 3 at 08:46 on 05-Jun-2014.
© NERC (CEH). © Crown copyright. © AA. 2009. All rights reserved.
66
500m
Rhydymwyn
 67009
500m
32
3
33 000m
67
31
Queensferry
Northop Hall
500m
500m
500m
Northop
Rhosesmor
68
500m
Wern-y-gaer
500m
30
Connah's Quay
500m
69
29
500m
28
500m
27
500m
26
500m
25
500m
24
500m
23
500m
22
500m
21
500m
20
500m
19
500m
500m
500m
70 000m
3
18 000m
3
500m
47
Rhosllanerchrugog
46 000m
500m
3
500m
500m
3
33 000m
Kilometres
32
500m
0
326900 359100 [SJ 26900 59100]
31
500m
30
500m
29
500m
28
500m
27
500m
26
500m
25
500m
24
500m
23
500m
22
500m
21
500m
20
500m
500m
18 000m
500m
3
500m
19
46 000m
2.5
5
VERSION
FEH CD-ROM Version
3 exported at
07:46:38 GMT Thu
CATCHMENT
GB
326900 359100 SJ 26900 59100
AREA
3.46
ALTBAR
223
ASPBAR
62
ASPVAR
0.61
BFIHOST
0.391
DPLBAR
2.28
DPSBAR
55.4
FARL
1
LDP
4.71
PROPWET
0.51
RMED-1H
10.3
RMED-1D
34.9
RMED-2D
44.6
SAAR
916
SAAR4170
865
SPRHOST
40.37
URBCONC1990
0.46
URBEXT1990
0.0161
URBLOC1990
1.032
C
-0.02766
D1
0.37189
D2
0.43866
D3
0.32148
E
0.28808
F
2.44194
C(1 km)
-0.026
D1(1 km)
0.362
D2(1 km)
0.428
D3(1 km)
0.324
E(1 km)
0.286
F(1 km)
2.427
05-Jun-14
Design Rainfall
FRA262 – FCA
APPENDIX K:
SURFACE WATER RUN-OFF DATA & CALCULATIONS
FRA262 – FCA
Betts Associates Ltd
Old Marsh Farm Barns
Welsh Road
Sealand Flintshire CH5 2LY
Date 26/06/14
File
Micro Drainage
Page 1
Station Yard
Corwen Road
Coed-Talon
Designed by KW
Checked by RDN
Network 2014.1
Rainfall profile
Storm duration (mins) 360
FEH Data
C(1km) -0.026
D1(1km) 0.362
D2(1km) 0.428
D3(1km) 0.324
E(1km) 0.286
F(1km) 2.427
Peak Intensity (mm/hr) 14.153
Ave. Intensity (mm/hr) 3.611
Return Period (years)
1
©1982-2014 XP Solutions
Welsh Road
Date 26.06.2014
File
Micro Drainage
Page 1
Station Yard
Corwen Road
Coed-Talon
Designed by KW
Checked by RDN
Network 2014.1
Rainfall profile
FEH Data
C(1km) -0.026
D1(1km) 0.362
D2(1km) 0.428
D3(1km) 0.324
E(1km) 0.286
F(1km) 2.427
30
Welsh Road
Date 26.06.2014
File
Micro Drainage
Page 1
Station Yard
Corwen Road
Coed-Talon
Designed by KW
Checked by RDN
Network 2014.1
Rainfall profile
FEH Data
C(1km) -0.026
D1(1km) 0.362
D2(1km) 0.428
D3(1km) 0.324
E(1km) 0.286
F(1km) 2.427
100
Welsh Road
Date 24/7/14
File
Micro Drainage
Page 1
Station Yard
Corwen Road
Coed-Talon
Designed by KW
Checked by RDN
Source Control 2014.1
ICP SUDS Mean Annual Flood
Input
1
Soil
0.300
Area (ha) 1.505
Urban
0.000
SAAR (mm)
916 Region Number Region 9
Results
l/s
QBAR Rural 3.8
QBAR Urban 3.8
Q1 year 3.3
Q1 year 3.3
Q30 years 6.6
Q100 years 8.2
Welsh Road
Date 24/7/14
File
Micro Drainage
Page 1
Station Yard
Corwen Road
Coed-Talon
Designed by KW
Checked by RDN
Greenfield Runoff Volume
FEH Data
1
Storm Duration (mins)
360
Site Location GB 326900 359100 SJ 26900 59100
C(1km)
-0.026
D1(1km)
0.362
D2(1km)
0.428
D3(1km)
0.324
E(1km)
0.286
F(1km)
2.427
Areal Reduction Factor
1.00
Area (ha)
1.505
SAAR (mm)
916
CWI
122.256
SPR Host
40.370
URBEXT (1990)
0.0161
Results
Percentage Runoff (%)
39.98
Greenfield Runoff Volume (m³) 130.361
Welsh Road
Date 24/7/14
File
Micro Drainage
Page 1
Station Yard
Corwen Road
Coed-Talon
Designed by KW
Checked by RDN
Greenfield Runoff Volume
FEH Data
100
Storm Duration (mins)
360
Site Location GB 326900 359100 SJ 26900 59100
C(1km)
-0.026
D1(1km)
0.362
D2(1km)
0.428
D3(1km)
0.324
E(1km)
0.286
F(1km)
2.427
Areal Reduction Factor
1.00
Area (ha)
1.505
SAAR (mm)
916
CWI
122.256
SPR Host
40.370
URBEXT (1990)
0.0161
Results
Percentage Runoff (%)
44.24
Greenfield Runoff Volume (m³) 433.939
SURFACE WATER RUN-OFF CALCULATION SHEET
Development
Project No.
Revision
Date
Station Yard, Corwen Road, Coed-Talon
FRA262
2.0
24/07/2014
Completed by
Checked by
KW
RDN
Areas
Total Area
Existing Impermeable
Existing pervious
2.900 ha
1.395 ha
1.505 ha
Catchment Charateristics
SAAR
916 mm
SPR
40.37 %
i1
14.15 mm/hr
Proposed Impermeable (total)
0.721 ha
i100
Proposed Impermeable (domestic only)
n/a
42.58 mm/hr
d1
ha
16.4 mm
d100
Run-off Rates
Pre-development
Impermeable
1yr
30yr
100yr
1yr
30yr
100yr
1yr
30yr
100yr
Pervious
Total
Post-development
Impermeable (total)
54.8
123.3
165.0
3.3
6.6
8.2
58.1
129.9
173.2
65 mm
Volumes
Pre-development
Impermeable
l/s
l/s
l/s
l/s
l/s
l/s
l/s
l/s
l/s
1yr
100yr
1yr
100yr
1yr
100yr
Pervious
Total
Post-development
Impermeable (total)
Impermeable (domestic only)
Impermeable (domestic only)
1yr
28.3 l/s
100yr+CC
110.9 l/s
1yr n/a
l/s
100yr+CC n/a
l/s
Reduction (total)
Reduction (domestic only)
228.8
906.8
130.4
433.9
359.1
1340.7
cu.m
cu.m
cu.m
cu.m
cu.m
cu.m
1yr
118.2 cu.m
100yr+CC
609.2 cu.m
1yr n/a
cu.m
100yr+CC n/a
cu.m
55%
n/a
731.4 cu.m
cu.m
Quick storage Estimate
Return Period
Return Period
Return Period
Return Period
1yr
30yr
100yr+CC
low
0
11
67
high
25
81
182
mean
12.5
46
124.5
Imp. Area (cu.m)
0.721
0.721
0.721
1yr
30yr
100yr+CC
0
0
15
24
63
130
12
31.5
72.5
0.721
0.721
0.721
Max. Discharge (l/s)
58.1
129.9
173.2
58.1
129.9
173.2
Rainfall
FEH
FEH
FEH
CC
0
0
30%
FSR
FSR
FSR
0
0
30%
APPENDIX L:
STORMWATER STORAGE ESTIMATES
FRA262 – FCA
Stormwater Storage Estimates
FEH – 1 Year Return Period Event
FSR – 1 Year Return Period Event
FEH – 30 Year Return Period Event
FSR – 30 Year Return Period Event
FEH – 100 Year Return Period Event with 30% Allowance for Climate Change
FSR – 100 Year Return Period Event with 30% Allowance for Climate Change
FRA262 – FCA
APPENDIX M: IMPERMEABLE AREAS PLANS
FRA262 – FCA
DO NOT SCALE
LEGEND
SITE BOUNDARY
PRE-DEVELOPMENT IMPERMEABLE AREAS:
BUILDINGS
AREAS OF HARDSTANDING
TOTAL IMPERMEABLE AREAS - 1.395ha (48%)
TOTAL SITE AREA - 2.900ha
A
23/07/14
KW
ISSUED TO SUPPORT THE FLOOD RISK ASSESSMENT
RDN
PRELIMINARY
STATION YARD
PRE-DEVELOPMENT
IMPERMEABLE AREAS PLAN
FRA264
101
A
APPENDIX N: OVERLAND FLOOD ROUTING PLANS
FRA262 – FCA
DO NOT SCALE
LEGEND
SITE BOUNDARY
OPEN CHANNEL/WATERCOURSE
PRE-DEVELOPMENT FLOOD FLOWS
A
23/07/14
KW
ISSUED TO SUPPORT THE FLOOD RISK ASSESSMENT
RDN
PRELIMINARY
STATION YARD
PRE-DEVELOPMENT
FRA264
103
A
APPENDIX O: PFRA/LFRMP/CFMP EXTRACTS
FRA262 – FCA
Preliminary Assessment Report June 2011
Figure 4.1 Locations of Past Floods in Flintshire.
7
Figure 5.1: Locally Agreed Surface Water Information
Flood Map for Surface Water 200 year > 0.3m deep
10
Figure 5.2a Places in Flintshire above Flood Risk Thresholds
Not To Scale
13
Sub-area 8
Mold
Our key partners are:
Local communities
D∑r Cymru Welsh Water
The issues in this
sub-area
This area is centred around the
towns of Mold and Rhydymwyn and
is predominantly urban.
Approximately 440 properties are
currently at risk from a 1% AEP flood
event, increasing to around 540
in the future. Flood defences have
recently been constructed to reduce
the likelihood of flooding direct
from the River Alyn.
Culverts and flow constrictions on
the tributaries of the River Alyn also
increase the likelihood of flooding
in Mold.
Many locations within Mold
and outlying communities are at
risk of flooding from surface water
run-off, local watercourses and
drainage systems.
• increased community and
individual awareness of their
flood risks and adoption of
actions both can take to
help themselves.
Mold is one of the major areas in
Flintshire identified for residential,
commercial and industrial growth
in North East Wales/West Cheshire.
Actions to implement
the policy include:
The vision and
preferred policy
Policy Option 4 – areas of low,
moderate or high flood risk where
we are already managing the flood
risk effectively but where we may
need to take further actions to keep
pace with climate change.
Our vision includes improved
integration of actions by all parties
to manage all sources of flood
risk, particularly local surface
water and sewer flooding in
Mold and Rhydymwyn.
Increased naturalisation of
watercourses and a reduction of
constrictions to flow and culverts.
Particularly in urban areas,
e.g. Mold.
We will continue to maintain
our defences, but it may not be
justifiable to increase their height in
the future. Our vision also includes:
• increased emphasis on actions
to manage the consequences of
flooding from all sources;
Encourage and support our partners
to produce local long term plans
to manage all sources of flooding
at Mold. These plans should
include an assessment of the
consequences of flooding, including
from overtopping of defences, and
actions to manage these. They
should consider future options and
investment needs for defences,
emergency planning and response,
and development control issues to
avoid inappropriate development
in high risk areas.
Work with partners to deliver over
time increased naturalisation of
watercourses and a reduction of
constrictions to flow and culverts
in Mold.
Encourage and support studies by
partners to identify surface water
and sewer flooding issues and
management options, in Mold
and Rhydymwyn.
Include the Mold area in the River
Dee Flood Forecasting Model.
Engage and advise the local
community, to encourage people
at risk to take action to help
themselves.
Mold Flood Alleviation Scheme,
implemented in 2006
Environment Agency Wales River Dee Catchment Flood Management Plan
21
FRA262 – FCA
APPENDIX P:
PHOTOGRAPHS
FRA262 – FCA
Watercourse Cross Sections
Station Yard
Coed-Talon
Cross Section Photographs
Land Surveyors and Consulting Engineers
Bank Hosue
The Paddock
Wilmslow Road
Cheshire
SK9 3HQ
September 2014
Section 1
Section 2
Section 3
Section 4 and Culvert Entrance
Brick Arch beyond Section 4
Culvert near to Section 5
Section 5
Section 6
Section 7
Downstream Culvert Entrance
APPENDIX Q:
REFH FLOW ESTIMATES
FRA262 – FCA
Revitalised FSR/FEH rainfall runoff method
Spreadsheet application report
User name
Company name
Project name
KW
Catchment name
Betts Associates
Catchment easting
Station Yard, Coed-Talon Catchment northing
Catchment area
Byr Brook
326750
358800
2.64
Date/time modelled
Version
16-Oct-2014 09:43
1.4
Summary of model setup
Design rainfall parameters
Loss model parameters
Return period (yr)
Duration (hr)
Timestep (hr)
Season
Routing model parameters
Baseflow model parameters
1.004
Cmax (mm)
287
Tp (hr)
1.64
BL (hr)
26.4
3.25
Cini (mm)
137
Up
0.65
BR
1.06
1
Uk
0.8
0.25
Winter
Summary of results
FEH DDF rainfall (mm)
11.6
Design rainfall (mm)
7.9
 factor
Peak rainfall (mm)
0.2
1.5
3
Peak flow (m /s)
1.1
Graph
Net rainfall
Direct runoff
m3/s
mm
0.1
0.0
0.1
0.0
0.2
0.0
0.2
0.0
0.4
0.0
0.6
0.1
0.8
0.1
0.6
0.2
0.4
0.3
0.3
0.4
0.2
0.6
0.1
0.7
0.1
0.8
0.0
0.9
0.0
0.9
0.0
0.9
0.0
0.8
0.0
0.7
0.0
0.7
0.0
0.6
0.0
0.5
0.0
0.4
0.0
0.4
0.0
0.3
0.0
0.3
0.0
0.2
0.0
0.2
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
3.9
3.9
Baseflow
m3/s
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
2.5
Total flow
m3/s
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.4
0.5
0.6
0.7
0.9
1.0
1.0
1.1
1.0
1.0
0.9
0.9
0.8
0.7
0.7
0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.3
0.2
0.2
0.2
0.2
0.2
0.2
6.4
ReFH Model Output: Byr Brook
1.8
1.2
1.6
1
1.4
1.2
0.8
Flow (m3/s)
Design Rainfall
mm
0.1
0.2
0.3
0.5
0.8
1.2
1.5
1.2
0.8
0.5
0.3
0.2
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
7.9
Rainfall (mm)
Results
Series
Unit
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
3.75
4.00
4.25
4.50
4.75
5.00
5.25
5.50
5.75
6.00
6.25
6.50
6.75
7.00
7.25
7.50
7.75
8.00
8.25
8.50
8.75
9.00
Total (mm)
BF0 (m3/s)
1
0.6
0.8
0.6
0.4
0.4
Time (hr)
0.2
0.2
0
0
0
Audit comments
Model run with ReFH dll version 1.4.0005
Catchment
Catchment descriptors imported from file
Catchment descriptor file = 'catchment characteristics.csv'
Catchment decriptor file exported from CD ROM version 3
Catchment descriptor file exported on 15-Oct-2014 09:43
BFIHOST value of 0.39 used
PROPWET value of 0.51 used
SAAR value of 923 used
DPLBAR value of 2.19 used
DPSBAR value of 52.6 used
URBEXT value of 0.0138 used
C value of -0.0278 used
D1 value of 0.37336 used
E value of 0.28835 used
F value of 2.44399 used
Rainfall
Recommended season is Winter, as URBEXT < 0.125
ReFH design standard Seasonal Correction Factor of 0.71 applied
ReFH design standard Areal Reduction Factor of 0.96 applied
Loss Model
CMax derived from catchment descriptors
ReFH design standard Cini used
ReFH design standard  factor used
Routing Model
Tp derived from catchment descriptors
ReFH design standard used for Up
ReFH design standard used for Uk
Page 1 of 2
2
Rainfall
4
Net rainfall
6
Total flow
8
Direct runoff
Baseflow
Baseflow Model
BL derived from catchment descriptors
BR derived from catchment descriptors
ReFH design standard BF0 used
Page 2 of 2
User name
Company name
Project name
KW
Catchment name
Betts Associates
Catchment easting
Catchment area
Byr Brook
326750
358800
2.64
Date/time modelled
Version
16-Oct-2014 09:55
1.4
Return period (yr)
100
Cmax (mm)
287
Tp (hr)
1.64
BL (hr)
26.4
Duration (hr)
3.25
Cini (mm)
137
Up
0.65
BR
1.06
 factor
0.83
Uk
0.8
Timestep (hr)
Season
0.25
Winter
Summary of results
58
39.8
Peak rainfall (mm)
0.2
7.8
3
Peak flow (m /s)
4.5
Graph
Net rainfall
Direct runoff
m3/s
mm
0.3
0.0
0.4
0.0
0.7
0.0
1.1
0.1
1.7
0.2
2.6
0.3
3.6
0.6
2.9
0.9
2.0
1.4
1.4
2.0
0.9
2.6
0.6
3.2
0.4
3.7
0.0
4.1
0.0
4.2
0.0
4.1
0.0
3.9
0.0
3.5
0.0
3.2
0.0
2.8
0.0
2.4
0.0
2.1
0.0
1.9
0.0
1.6
0.0
1.4
0.0
1.1
0.0
0.9
0.0
0.7
0.0
0.6
0.0
0.4
0.0
0.2
0.0
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
18.6
18.6
Baseflow
m3/s
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.4
0.4
0.5
0.5
0.5
0.5
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
5.2
Total flow
m3/s
0.2
0.2
0.2
0.2
0.3
0.5
0.7
1.1
1.6
2.2
2.9
3.5
4.0
4.4
4.5
4.5
4.3
4.0
3.7
3.3
3.0
2.7
2.4
2.2
2.0
1.7
1.5
1.3
1.2
1.0
0.8
0.7
0.7
0.6
0.6
0.6
0.6
23.8
9
5
8
4.5
4
7
3.5
6
3
5
Flow (m3/s)
Design Rainfall
mm
0.7
1.1
1.7
2.6
4.0
6.0
7.8
6.0
4.0
2.6
1.7
1.1
0.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
39.8
Rainfall (mm)
Results
Series
Unit
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
3.75
4.00
4.25
4.50
4.75
5.00
5.25
5.50
5.75
6.00
6.25
6.50
6.75
7.00
7.25
7.50
7.75
8.00
8.25
8.50
8.75
9.00
Total (mm)
BF0 (m3/s)
2.5
4
2
3
1.5
2
1
Time (hr)
1
0.5
0
0
0
Audit comments
Catchment
Rainfall
Loss Model
Routing Model
Page 1 of 2
2
Rainfall
4
Net rainfall
6
Total flow
8
Direct runoff
Baseflow
Baseflow Model
Page 2 of 2
User name
Company name
Project name
KW
Catchment name
Betts Associates
Catchment easting
Catchment area
Byr Brook
326750
358800
2.64
Date/time modelled
Version
16-Oct-2014 09:57
1.4
Return period (yr)
1000
Cmax (mm)
287
Tp (hr)
1.64
BL (hr)
26.4
Duration (hr)
3.25
Cini (mm)
137
Up
0.65
BR
1.06
 factor
0.7
Uk
0.8
Timestep (hr)
Season
0.25
Winter
Summary of results
104.5
71.8
Peak rainfall (mm)
0.2
14
3
Peak flow (m /s)
8
Graph
Net rainfall
Direct runoff
m3/s
mm
0.4
0.0
0.7
0.0
1.1
0.0
1.7
0.1
2.8
0.3
4.5
0.5
6.5
0.9
5.4
1.5
3.8
2.4
2.6
3.4
1.7
4.5
1.1
5.6
0.7
6.5
0.0
7.2
0.0
7.5
0.0
7.3
0.0
7.0
0.0
6.4
0.0
5.8
0.0
5.1
0.0
4.5
0.0
3.9
0.0
3.4
0.0
2.9
0.0
2.5
0.0
2.1
0.0
1.7
0.0
1.4
0.0
1.0
0.0
0.7
0.0
0.5
0.0
0.3
0.0
0.2
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
33.1
33.1
Baseflow
m3/s
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.4
0.4
0.5
0.6
0.6
0.7
0.8
0.8
0.8
0.9
0.9
0.9
0.9
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.9
0.9
0.9
7.9
Total flow
m3/s
0.2
0.2
0.2
0.3
0.4
0.6
1.0
1.7
2.6
3.6
4.8
5.9
6.9
7.6
8.0
7.9
7.6
7.1
6.5
5.9
5.3
4.8
4.3
3.8
3.4
3.1
2.7
2.3
2.0
1.7
1.4
1.3
1.1
1.0
1.0
0.9
0.9
41.0
16
9
14
8
7
12
6
10
5
8
4
6
3
4
2
Time (hr)
2
1
0
0
0
Audit comments
Catchment
Rainfall
Loss Model
Routing Model
Page 1 of 2
2
Rainfall
4
Net rainfall
6
Total flow
8
Direct runoff
Baseflow
Flow (m3/s)
Design Rainfall
mm
1.3
2.0
3.1
4.7
7.2
10.8
14.0
10.8
7.2
4.7
3.1
2.0
1.3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
71.8
Rainfall (mm)
Results
Series
Unit
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
3.75
4.00
4.25
4.50
4.75
5.00
5.25
5.50
5.75
6.00
6.25
6.50
6.75
7.00
7.25
7.50
7.75
8.00
8.25
8.50
8.75
9.00
Total (mm)
BF0 (m3/s)
Baseflow Model
Page 2 of 2
User name
Company name
Project name
KW
Catchment name
Betts Associates
Catchment easting
Catchment area
Unnamed Tributary
326650
358850
0.69
Date/time modelled
Version
16-Oct-2014 10:16
1.4
Return period (yr)
Duration (hr)
Timestep (hr)
Season
1.004
Cmax (mm)
288
Tp (hr)
1.06
BL (hr)
22.5
2.13
Cini (mm)
137
Up
0.65
BR
1.07
1
Uk
0.8
0.142
Winter
 factor
Summary of results
9.6
Peak rainfall (mm)
6.3
Peak flow (m /s)
0
1.1
3
0.3
Graph
Net rainfall
Direct runoff
m3/s
mm
0.0
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.2
0.0
0.3
0.0
0.4
0.0
0.5
0.0
0.4
0.1
0.3
0.1
0.2
0.1
0.1
0.2
0.1
0.2
0.1
0.2
0.0
0.3
0.0
0.3
0.0
0.3
0.0
0.3
0.0
0.3
0.0
0.2
0.0
0.2
0.0
0.2
0.0
0.2
0.0
0.2
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
3.1
3.1
Baseflow
m3/s
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
1.6
Total flow
m3/s
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.2
0.2
0.2
0.2
0.2
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
4.7
ReFH Model Output: Unnamed Tributary
1.2
0.35
0.3
1
0.25
0.8
Flow (m3/s)
Design Rainfall
mm
0.1
0.1
0.2
0.3
0.4
0.6
0.9
1.1
0.9
0.6
0.4
0.3
0.2
0.1
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
6.3
Rainfall (mm)
Results
Series
Unit
0.000
0.142
0.284
0.426
0.568
0.710
0.852
0.994
1.136
1.278
1.420
1.562
1.704
1.846
1.988
2.130
2.272
2.414
2.556
2.698
2.840
2.982
3.124
3.266
3.408
3.550
3.692
3.834
3.976
4.118
4.260
4.402
4.544
4.686
4.828
4.970
5.112
5.254
5.396
5.538
5.680
5.822
Total (mm)
BF0 (m3/s)
0.2
0.6
0.15
0.4
0.1
Time (hr)
0.2
0.05
0
0
0
Audit comments
Catchment
Rainfall
Loss Model
Routing Model
Page 1 of 2
1
Rainfall
2
Net rainfall
3
Total flow
4
5
Direct runoff
Baseflow
Baseflow Model
Page 2 of 2
User name
Company name
Project name
KW
Catchment name
Betts Associates
Catchment easting
Catchment area
Unnamed Tributary
326650
358850
0.69
Date/time modelled
Version
16-Oct-2014 10:28
1.4
Return period (yr)
100
Cmax (mm)
288
Tp (hr)
1.06
BL (hr)
22.5
Duration (hr)
2.13
Cini (mm)
137
Up
0.65
BR
1.07
 factor
0.83
Uk
0.8
Timestep (hr)
Season
0.142
Winter
Summary of results
51.5
Peak rainfall (mm)
34.1
Peak flow (m /s)
0
5.8
3
1.5
Graph
Net rainfall
Direct runoff
m3/s
mm
0.2
0.0
0.3
0.0
0.4
0.0
0.6
0.0
0.9
0.0
1.4
0.1
2.0
0.1
2.6
0.2
2.2
0.3
1.6
0.5
1.1
0.6
0.8
0.8
0.6
1.0
0.4
1.2
0.3
1.3
0.0
1.4
0.0
1.4
0.0
1.4
0.0
1.3
0.0
1.2
0.0
1.1
0.0
1.0
0.0
0.9
0.0
0.8
0.0
0.7
0.0
0.6
0.0
0.6
0.0
0.5
0.0
0.4
0.0
0.4
0.0
0.3
0.0
0.2
0.0
0.2
0.0
0.1
0.0
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
15.5
15.5
Baseflow
m3/s
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
3.4
Total flow
m3/s
0.0
0.0
0.0
0.1
0.1
0.1
0.2
0.2
0.4
0.5
0.7
0.9
1.1
1.2
1.4
1.5
1.5
1.5
1.4
1.4
1.3
1.2
1.0
1.0
0.9
0.8
0.7
0.6
0.6
0.5
0.5
0.4
0.3
0.3
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
18.9
7
1.6
6
1.4
1.2
5
1
4
Flow (m3/s)
Design Rainfall
mm
0.5
0.7
1.1
1.6
2.3
3.3
4.7
5.8
4.7
3.3
2.3
1.6
1.1
0.7
0.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
34.1
Rainfall (mm)
Results
Series
Unit
0.000
0.142
0.284
0.426
0.568
0.710
0.852
0.994
1.136
1.278
1.420
1.562
1.704
1.846
1.988
2.130
2.272
2.414
2.556
2.698
2.840
2.982
3.124
3.266
3.408
3.550
3.692
3.834
3.976
4.118
4.260
4.402
4.544
4.686
4.828
4.970
5.112
5.254
5.396
5.538
5.680
5.822
Total (mm)
BF0 (m3/s)
0.8
3
0.6
2
0.4
Time (hr)
1
0.2
0
0
0
Audit comments
Catchment
Rainfall
Loss Model
Routing Model
Page 1 of 2
1
Rainfall
2
Net rainfall
3
Total flow
4
5
Direct runoff
Baseflow
Baseflow Model
Page 2 of 2
User name
Company name
Project name
KW
Catchment name
Betts Associates
Catchment easting
Catchment area
Unnamed Tributary
326650
358850
0.69
Date/time modelled
Version
16-Oct-2014 10:29
1.4
Return period (yr)
1000
Cmax (mm)
288
Tp (hr)
1.06
BL (hr)
22.5
Duration (hr)
2.13
Cini (mm)
137
Up
0.65
BR
1.07
 factor
0.7
Uk
0.8
Timestep (hr)
Season
0.142
Winter
Summary of results
95.3
63
Peak rainfall (mm)
0
10.8
3
Peak flow (m /s)
2.7
Graph
Net rainfall
Direct runoff
m3/s
mm
0.3
0.0
0.5
0.0
0.7
0.0
1.0
0.0
1.6
0.1
2.3
0.1
3.5
0.2
4.8
0.3
4.1
0.5
3.1
0.8
2.2
1.1
1.6
1.4
1.1
1.7
0.8
2.0
0.5
2.3
0.0
2.5
0.0
2.5
0.0
2.5
0.0
2.4
0.0
2.3
0.0
2.1
0.0
1.9
0.0
1.7
0.0
1.5
0.0
1.3
0.0
1.2
0.0
1.0
0.0
0.9
0.0
0.8
0.0
0.7
0.0
0.5
0.0
0.4
0.0
0.3
0.0
0.2
0.0
0.2
0.0
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
28.0
28.0
Baseflow
m3/s
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
5.2
Total flow
m3/s
0.0
0.0
0.1
0.1
0.1
0.2
0.2
0.4
0.6
0.8
1.1
1.5
1.8
2.1
2.4
2.6
2.7
2.7
2.6
2.4
2.3
2.1
1.9
1.7
1.6
1.4
1.3
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.4
0.3
0.3
0.3
0.3
0.3
0.3
33.2
12
3
10
2.5
8
2
6
1.5
4
1
Flow (m3/s)
Design Rainfall
mm
0.9
1.4
2.0
2.9
4.2
6.1
8.6
10.8
8.6
6.1
4.2
2.9
2.0
1.4
0.9
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
63.0
Rainfall (mm)
Results
Series
Unit
0.000
0.142
0.284
0.426
0.568
0.710
0.852
0.994
1.136
1.278
1.420
1.562
1.704
1.846
1.988
2.130
2.272
2.414
2.556
2.698
2.840
2.982
3.124
3.266
3.408
3.550
3.692
3.834
3.976
4.118
4.260
4.402
4.544
4.686
4.828
4.970
5.112
5.254
5.396
5.538
5.680
5.822
Total (mm)
BF0 (m3/s)
Time (hr)
2
0.5
0
0
0
Audit comments
Catchment
Rainfall
Loss Model
Routing Model
Page 1 of 2
1
Rainfall
2
Net rainfall
3
Total flow
4
5
Direct runoff
Baseflow
Baseflow Model
Page 2 of 2
FRA262 – FCA
APPENDIX R:
1D MODELLING OUTPUTS - EXISTING
FRA262 – FCA
2
Tr
ib
367.94
121.355
Junc.1
By
3
r
o
Br
ok
206.209
239.269
232.359
None of the XS's are Geo-Referenced ( Geo-Ref user entered XS Geo-Ref interpolated XS Non Geo-Ref user entered XS Non Geo-Ref interpolated XS)
.
165.156
473.49
486.70
1
na
me
d
184.87
500
Un
200
ok
Br o
By
r
184.716
Station Yard, Coed-Talon
Plan: St. Yd. Existing
10/11/2014
Section 1
.1
10/11/2014
Section 2
.017
.1
.1
143.5
.017
.1
143.5
Legend
Legend
WS Q1000
WS Q1000
143.0
143.0
WS Q100
142.5
WS Q1
Ground
142.0
WS Q100+CCA
Elevation (m)
Elevation (m)
WS Q100+CCA
WS Q100
142.5
WS Q1
Ground
142.0
Bank Sta
Bank Sta
141.5
141.5
141.0
141.0
0
1
2
3
4
5
6
7
0
1
2
3
Station (m)
5
6
7
Station (m)
10/11/2014
Section 3
.1
4
.017
10/11/2014
Section 4
.1
143.5
.
143.5 1
Legend
WS Q1000
143.0
.017
.1
Legend
WS Q100+CCA
143.0
WS Q100
WS Q1
142.0
Ground
141.5
Bank Sta
141.0
WS Q100
Elevation (m)
Elevation (m)
WS Q100+CCA
142.5
142.5
WS Q1000
WS Q1
142.0
Ground
141.5
Bank Sta
141.0
140.5
140.5
0
1
2
3
Station (m)
4
5
0
1
2
3
Station (m)
4
5
10/11/2014
Culvert 1
.
143.5 1
.017
10/11/2014
Culvert 1
.1
.1
WS Q100+CCA
143.0
.017
.06
141.5
Legend
Legend
WS Q1000
141.0
WS Q1000
WS Q1
142.0
Ground
141.5
WS Q100+CCA
Elevation (m)
Elevation (m)
WS Q100
142.5
Bank Sta
141.0
140.5
WS Q100
WS Q1
140.0
Ground
139.5
Bank Sta
139.0
140.5
138.5
0
1
2
3
4
5
0
2
4
6
Station (m)
10
12
14
16
Station (m)
10/11/2014
Section 4a
.1
8
10/11/2014
Section 4a2
.017
.06
.1
141.5
WS Q1000
141.0
.017
.06
141.5
Legend
Legend
WS Q1000
141.0
WS Q100
WS Q1
140.0
Ground
139.5
Bank Sta
139.0
WS Q100+CCA
Elevation (m)
Elevation (m)
WS Q100+CCA
140.5
140.5
WS Q100
WS Q1
140.0
Ground
139.5
Bank Sta
139.0
138.5
138.5
0
2
4
6
8
Station (m)
10
12
14
16
0
2
4
6
8
Station (m)
10
12
14
16
10/11/2014
Section 4b
.1
.017
.06
.1
141.5
10/11/2014
WS Q100+CCA
WS Q1
Ground
139.5
Bank Sta
139.0
Legend
WS Q1000
WS Q100+CCA
140.5
Elevation (m)
WS Q100
140.0
.06
141.0
WS Q1000
140.5
.017
141.5
Legend
141.0
Elevation (m)
Culvert 2
WS Q100
140.0
WS Q1
Ground
139.5
Bank Sta
139.0
138.5
138.5
138.0
138.0
0
2
4
6
8
10
12
0
2
4
Station (m)
6
10
12
Station (m)
10/11/2014
Culvert 2
.1
8
10/11/2014
Section 4c
.017
.07
.1
141
.017
.07
141
Legend
Legend
WS Q1000
WS Q1000
140
140
WS Q100
139
WS Q1
Ground
138
WS Q100+CCA
Elevation (m)
Elevation (m)
WS Q100+CCA
WS Q100
139
WS Q1
Ground
138
Bank Sta
137
Bank Sta
137
136
136
0
2
4
6
8
Station (m)
10
12
14
0
2
4
6
8
Station (m)
10
12
14
10/11/2014
Section 5
.1
.017
.07
.1
140.0
10/11/2014
139.5
WS Q1000
139.0
WS Q100+CCA
WS Q100
138.5
WS Q1
138.0
Ground
137.5
.017
.07
141
Legend
Legend
WS Q1000
140
WS Q100+CCA
Elevation (m)
Elevation (m)
Section 6
Bank Sta
139
WS Q100
WS Q1
138
Ground
137
Bank Sta
137.0
136
136.5
136.0
135
0
5
10
15
20
25
0
5
10
15
Station (m)
25
30
35
40
Station (m)
10/11/2014
Section 7
.1
20
10/11/2014
Section U
.017
.06
.1
141
.
0
1
7
144.0
Legend
WS Q1000
140
.1
Legend
WS Q1000
143.5
WS Q100
WS Q1
138
Ground
137
WS Q100+CCA
Elevation (m)
Elevation (m)
WS Q100+CCA
139
WS Q100
143.0
WS Q1
Ground
142.5
Bank Sta
Bank Sta
142.0
136
135
141.5
0
5
10
15
Station (m)
20
25
30
0
5
10
Station (m)
15
20
10/11/2014
Section V
.1
.017
.1
.1
144.0
WS Q100
WS Q1
142.5
Ground
142.0
Legend
WS Q1000
WS Q100+CCA
143.0
Elevation (m)
143.0
.017
143.5
WS Q1000
WS Q100+CCA
Elevation (m)
10/11/2014
144.0
Legend
143.5
Bank Sta
WS Q100
142.5
WS Q1
Ground
142.0
Bank Sta
141.5
141.5
141.0
141.0
140.5
0
5
10
15
20
0
2
4
6
Station (m)
8
10
12
14
16
18
Station (m)
10/11/2014
Section X
10/11/2014
Section Y
.1
.017
.1
.1
144.0
143.5
WS Q100+CCA
143.0
WS Q100+CCA
142.5
WS Q100
WS Q100
142.5
WS Q1
Ground
142.0
Legend
WS Q1000
Elevation (m)
143.0
. .
0 1
1
7
144.0
Legend
143.5
Elevation (m)
Section W
WS Q1000
WS Q1
142.0
Ground
141.5
Bank Sta
141.5
Bank Sta
141.0
141.0
140.5
140.5
140.0
0
2
4
6
8
10
Station (m)
12
14
16
18
0
2
4
6
8
10
Station (m)
12
14
16
18
10/11/2014
Section Z
.1
.
0
1
7
143.5
143.0
.1
.1
143.0
WS Q1000
WS Q100+CCA
10/11/2014
WS Q1
Ground
141.5
Bank Sta
141.0
.1
Legend
WS Q1000
WS Q100
142.5
Elevation (m)
WS Q100
142.0
.
0
1
7
143.5
Legend
142.5
Elevation (m)
Culvert 3
WS Q100+CCA
142.0
WS Q1
Ground
141.5
Bank Sta
141.0
140.5
140.5
140.0
140.0
0
5
10
15
20
25
0
5
10
Station (m)
15
20
25
Station (m)
10/11/2014
Culvert 3
10/11/2014
Section Za
.017
.017
141.5
141.5
Legend
WS Q1000
141.0
Legend
WS Q1000
141.0
WS Q100
WS Q1
140.0
Ground
139.5
Bank Sta
139.0
WS Q100+CCA
Elevation (m)
Elevation (m)
WS Q100+CCA
140.5
140.5
WS Q100
WS Q1
140.0
Ground
139.5
Bank Sta
139.0
138.5
138.5
0
1
2
3
Station (m)
4
5
6
0
1
2
3
Station (m)
4
5
6
Byr Brook 3
10/11/2014
Byr Brook 1
Unnamed Trib. 2
144
Legend
WS Q1000
WS Q100+CCA
WS Q100
WS Q1
142
Ground
Elevation (m)
140
138
136
134
0
50
100
150
200
Main Channel Distance (m)
250
300
350
10/11/2014
Legend
WS Q1
WS Q100
WS Q100+CCA
WS Q1000
Ground
Bank Sta
200
184.87
165.156
206.209
367.94
121.355
239.269
184.716
232.359
486.70
HEC-RAS Plan: St.Yd. Existing
River
Reach
River Sta
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
200
200
200
Unnamed Trib.
2
Unnamed Trib.
2
Unnamed Trib.
Unnamed Trib.
Profile
Q Total
Min Ch El
W.S. Elev
Crit W.S.
E.G. Elev
E.G. Slope
Vel Chnl
Flow Area
Top Width
(m3/s)
(m)
(m)
(m)
(m)
(m/m)
(m/s)
(m2)
(m)
Froude # Chl
Q1
Q100
Q100+CCA
0.30
1.50
1.80
141.96
141.96
141.96
142.24
142.63
142.69
142.24
142.63
142.69
142.35
142.86
142.95
0.004607
0.003197
0.003123
1.46
2.35
2.49
0.30
1.61
1.94
2.05
4.76
5.23
0.98
0.96
0.97
200
Q1000
2.70
141.96
142.87
142.87
143.17
0.002920
2.80
2.92
6.03
0.97
184.87
Q1
0.30
141.43
141.64
141.64
141.71
0.005774
1.13
0.27
2.15
1.00
2
2
184.87
184.87
Q100
Q100+CCA
1.50
1.80
141.43
141.43
141.89
141.93
141.89
141.93
142.06
142.13
0.003988
0.003790
1.88
1.99
0.95
1.12
3.45
3.70
0.99
0.99
Unnamed Trib.
2
184.87
Q1000
2.70
141.43
142.06
142.06
142.31
0.003413
2.25
1.63
4.46
0.98
Unnamed Trib.
Unnamed Trib.
2
2
182.862
182.862
Q1
Q100
0.30
1.50
140.94
140.94
141.37
141.76
141.37
141.76
141.48
141.98
0.007531
0.005781
1.47
2.06
0.20
0.76
0.94
2.30
1.01
0.99
Unnamed Trib.
2
182.862
Q100+CCA
1.80
140.94
141.82
141.82
142.06
0.005462
2.14
0.92
2.80
0.97
Unnamed Trib.
2
182.862
Q1000
2.70
140.94
141.99
141.99
142.26
0.004893
2.35
1.49
4.10
0.94
Unnamed Trib.
2
180.942
Q1
0.30
140.82
141.05
141.05
141.11
0.006101
1.07
0.28
2.45
1.01
Unnamed Trib.
Unnamed Trib.
2
2
180.942
180.942
Q100
Q100+CCA
1.50
1.80
140.82
140.82
141.54
141.70
141.57
141.73
0.000394
0.000248
0.78
0.73
2.09
2.80
4.35
4.72
0.33
0.28
Unnamed Trib.
2
180.942
Q1000
2.70
140.82
141.88
141.92
0.000262
0.87
3.67
5.15
0.29
Unnamed Trib.
2
176.548
Q1
0.30
140.40
140.72
140.81
0.006120
1.36
0.23
1.46
1.01
Unnamed Trib.
Unnamed Trib.
2
2
176.548
176.548
Q100
Q100+CCA
1.50
1.80
140.40
140.40
141.51
141.67
141.57
141.72
0.000457
0.000386
1.13
1.14
2.88
3.73
5.21
5.92
0.36
0.34
Unnamed Trib.
2
176.548
Q1000
2.70
140.40
141.82
141.91
0.000539
1.46
4.69
6.64
0.41
Unnamed Trib.
Unnamed Trib.
2
2
165.156
165.156
Q1
Q100
0.30
1.50
140.07
140.07
140.53
141.13
140.53
141.13
140.69
141.52
0.006676
0.004464
1.78
2.91
0.20
0.96
0.81
1.74
0.99
0.96
Unnamed Trib.
2
165.156
Q100+CCA
1.80
140.07
141.25
141.25
141.67
0.004113
3.03
1.19
1.94
0.95
Unnamed Trib.
2
165.156
Q1000
2.70
140.07
141.64
141.64
141.88
0.001973
2.59
4.69
12.02
0.69
Unnamed Trib.
2
164.156
Unnamed Trib.
Unnamed Trib.
2
2
121.355
121.355
Q1
Q100
0.30
1.50
138.53
138.53
139.16
140.09
139.16
140.09
0.000006
0.000009
0.09
0.17
3.31
8.66
5.75
5.75
0.04
0.05
Unnamed Trib.
2
121.355
Q100+CCA
1.80
138.53
140.38
140.38
0.000007
0.17
10.35
5.75
0.04
Unnamed Trib.
2
121.355
Q1000
2.70
138.53
141.27
141.28
0.000006
0.17
15.49
5.75
0.03
Byr Brook
Byr Brook
1
1
500
500
Q1
Q100
1.10
4.50
141.20
141.20
141.76
142.93
141.80
142.96
0.000792
0.000180
0.85
0.75
1.29
6.06
2.87
5.18
0.41
0.21
Byr Brook
Byr Brook
1
1
500
500
Q100+CCA
Q1000
5.40
8.00
141.20
141.20
143.04
143.39
143.08
143.44
0.000196
0.000203
0.83
0.98
6.69
9.04
6.21
6.80
0.22
0.24
Byr Brook
Byr Brook
1
1
486.70
486.70
Q1
Q100
1.10
4.50
141.09
141.09
141.78
142.94
141.79
142.95
0.000145
0.000087
0.45
0.57
2.44
7.85
4.14
5.10
0.19
0.15
Byr Brook
Byr Brook
1
1
486.70
486.70
Q100+CCA
Q1000
5.40
8.00
141.09
141.09
143.05
143.40
143.07
143.44
0.000103
0.000118
0.64
0.78
8.43
10.65
5.18
6.60
0.16
0.18
Byr Brook
Byr Brook
1
1
477.04
477.04
Q1
Q100
1.10
4.50
140.69
140.69
141.47
142.73
141.47
141.76
142.93
0.011753
0.003071
2.39
1.98
0.46
2.47
0.79
4.44
1.00
0.53
Byr Brook
1
477.04
Q100+CCA
5.40
140.69
142.78
142.35
143.04
0.003962
2.30
2.66
4.47
0.61
Byr Brook
1
477.04
Q1000
8.00
140.69
142.97
142.78
143.39
0.005420
2.92
3.55
4.53
0.73
Byr Brook
Byr Brook
Byr Brook
1
1
1
473.49
473.49
473.49
Q1
Q100
Q100+CCA
1.10
4.50
5.40
140.66
140.66
140.66
141.16
142.72
142.75
141.16
141.95
142.10
141.41
142.92
143.03
0.008747
0.003019
0.004127
2.19
1.98
2.34
0.50
2.49
2.61
1.03
4.05
4.59
1.00
0.46
0.54
Byr Brook
1
473.49
Q1000
8.00
140.66
142.50
142.50
143.32
0.014673
4.02
2.00
1.43
1.00
Byr Brook
1
472.49
Byr Brook
Byr Brook
1
1
367.94
367.94
Q1
Q100
1.10
4.50
138.56
138.56
139.10
140.00
139.15
140.08
0.001246
0.000775
1.03
1.29
1.07
3.49
2.37
3.02
0.49
0.38
Byr Brook
Byr Brook
1
1
367.94
367.94
Q100+CCA
Q1000
5.40
8.00
138.56
138.56
140.30
141.22
140.38
141.27
0.000589
0.000264
1.22
1.03
4.44
9.53
3.24
14.10
0.33
0.22
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
364.253
364.253
364.253
364.253
Q1
Q100
Q100+CCA
Q1000
1.40
6.00
7.20
10.70
138.56
138.56
138.56
138.56
138.97
139.89
140.22
141.16
138.97
139.14
140.07
140.37
141.27
0.005329
0.001794
0.001239
0.000519
1.82
1.90
1.73
1.42
0.77
3.16
4.17
8.77
2.28
2.95
3.18
14.10
1.00
0.58
0.48
0.31
Byr Brook
3
360.566
Q1
1.40
138.37
138.79
138.79
138.95
0.005175
1.74
0.80
2.65
1.01
Byr Brook
Byr Brook
Byr Brook
3
3
3
360.566
360.566
360.566
Q100
Q100+CCA
Q1000
6.00
7.20
10.70
138.37
138.37
138.37
139.95
140.26
141.19
139.29
139.39
139.65
140.04
140.34
141.25
0.000677
0.000510
0.000237
1.32
1.24
1.06
4.55
5.79
11.22
3.81
4.12
11.43
0.39
0.33
0.23
Byr Brook
3
359.566
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
239.269
239.269
239.269
239.269
Q1
Q100
Q100+CCA
Q1000
1.40
6.00
7.20
10.70
136.28
136.28
136.28
136.28
137.32
138.15
138.28
138.63
137.32
138.15
138.28
138.63
137.58
138.61
138.79
139.23
0.009240
0.007459
0.007239
0.006021
2.28
3.03
3.15
3.44
0.61
1.98
2.29
3.40
1.18
2.12
2.36
4.29
1.01
1.00
1.00
0.95
Byr Brook
Byr Brook
3
3
232.359
232.359
Q1
Q100
1.40
6.00
136.35
136.35
136.67
137.12
136.67
137.12
136.80
137.40
0.004896
0.004079
1.63
2.37
0.86
2.53
3.19
4.47
1.01
1.01
Byr Brook
Byr Brook
3
3
232.359
232.359
Q100+CCA
Q1000
7.20
10.70
136.35
136.35
137.20
137.40
137.20
137.40
137.51
137.78
0.003991
0.003612
2.47
2.71
2.92
4.16
4.77
7.63
1.01
0.99
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
206.209
206.209
206.209
206.209
Q1
Q100
Q100+CCA
Q1000
1.40
6.00
7.20
10.70
135.96
135.96
135.96
135.96
136.30
136.71
136.79
137.02
136.30
136.71
136.79
137.02
136.43
137.01
137.12
137.40
0.005189
0.003939
0.003640
0.002991
1.58
2.42
2.54
2.78
0.89
2.56
3.11
5.35
3.54
5.69
7.25
11.16
1.01
1.00
0.98
0.93
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
184.716
184.716
184.716
184.716
Q1
Q100
Q100+CCA
Q1000
1.40
6.00
7.20
10.70
135.46
135.46
135.46
135.46
135.79
136.18
136.26
136.48
135.79
136.18
136.26
136.48
135.91
136.50
136.62
136.94
0.004865
0.003500
0.003377
0.003070
1.54
2.49
2.65
3.02
0.91
2.50
2.84
3.82
3.83
4.27
4.36
4.74
1.00
1.00
1.00
1.00
140.72
Culvert
Culvert
Culvert
HEC-RAS Plan: St.Yd. Existing
River
Reach
River Sta
Profile
E.G. US.
W.S. US.
E.G. IC
E.G. OC
Min El Weir Flow
Q Culv Group
Q Weir
Delta WS
Culv Vel US
Culv Vel DS
(m)
(m)
(m)
(m)
(m)
(m3/s)
(m3/s)
(m)
(m/s)
(m/s)
Unnamed Trib.
2
164.156 Culvert 3
Q1
140.62
140.53
140.59
140.62
141.35
0.30
Unnamed Trib.
2
164.156 Culvert 3
Q100
141.48
141.13
141.55
141.48
141.35
1.40
Unnamed Trib.
2
164.156 Culvert 3
Q100+CCA
141.58
141.25
141.60
141.58
141.35
1.36
0.44
Unnamed Trib.
2
164.156 Culvert 3
Q1000
141.75
141.64
141.72
141.75
141.35
0.85
1.85
Byr Brook
1
472.49 Culvert 1
Q1
141.34
141.16
141.25
141.34
142.37
1.10
2.06
1.98
1.41
Byr Brook
1
472.49 Culvert 1
Q100
142.92
142.72
142.79
142.92
142.37
3.09
1.41
2.72
2.60
2.60
Byr Brook
1
472.49 Culvert 1
Q100+CCA
143.03
142.75
142.89
143.03
142.37
2.99
2.41
2.45
2.51
2.51
Byr Brook
1
472.49 Culvert 1
Q1000
143.27
142.50
143.12
143.27
142.37
2.59
5.41
1.28
2.18
2.18
Byr Brook
3
359.566 Culvert 2
Q1
138.87
138.79
138.83
138.87
141.01
1.40
1.47
1.98
0.73
Byr Brook
3
359.566 Culvert 2
Q100
140.04
139.95
140.33
140.04
141.01
6.00
1.80
3.08
3.08
Byr Brook
3
359.566 Culvert 2
Q100+CCA
140.35
140.26
140.85
140.35
141.01
7.20
1.98
3.70
3.70
Byr Brook
3
359.566 Culvert 2
Q1000
141.25
141.19
141.28
141.25
141.01
8.43
2.56
4.33
4.33
0.10
2.27
1.37
1.58
0.76
1.04
3.16
3.16
0.87
3.07
3.07
0.37
1.93
1.93
APPENDIX S:
FRA262 – FCA
A
FRA262
500
STATION YARD
COED-TALON
PRELIMINARY
05/11/2014 RDN ISSUED TO SUPPORT THE FRA
Overland Flow Rates
Minor Contours (0.2m Intervals)
Major Contours (1m Intervals)
Approximate Red Edge Boundary
LEGEND
DO NOT SCALE
A
KW
APPENDIX T:
1D MODELLING SENSIVITY TESTING OUTPUTS
FRA262 – FCA
Plan:
1) +20% Flow
Byr Brook 3
10/11/2014
2) -20% Flow
10/11/2014
3) St.Yd. Existing
10/11/2014
Byr Brook 1
Unnamed Trib. 2
144
Legend
WS Q100 - +20% Flow
WS Q100 - St.Yd. Existing
WS Q100 - -20% Flow
Ground
142
Elevation (m)
140
138
136
134
0
50
100
150
200
250
300
350
Plan:
1) +20% S.Depth
Byr Brook 3
09/11/2014
2) -20% S.Depth
09/11/2014
3) St.Yd. Existing
10/11/2014
Byr Brook 1
Unnamed Trib. 2
Legend
WS Q1000 - +20% S.Depth
WS Q1000 - -20% S.Depth
142
WS Q100+CCA - -20% S.Depth
WS Q100+CCA - St.Yd. Existing
WS Q100+CCA - +20% S.Depth
WS Q100 - +20% S.Depth
140
WS Q100 - -20% S.Depth
Elevation (m)
WS Q1 - +20% S.Depth
WS Q1 - -20% S.Depth
Ground
138
136
0
50
100
150
200
250
300
350
Plan:
1) St.Yd. Existing
Byr Brook 3
10/11/2014
2) St.Yd. Mn +10%
09/11/2014
3) St. Yd. Mn -10%
09/11/2014
Byr Brook 1
Unnamed Trib. 2
144
Legend
WS Q1000 - St.Yd. Mn +10%
WS Q1000 - St. Yd. Mn -10%
WS Q100+CCA - St.Yd. Mn +10%
142
WS Q100+CCA - St. Yd. Mn -10%
WS Q100 - St. Yd. Mn -10%
WS Q100 - St.Yd. Mn +10%
140
Elevation (m)
WS Q1 - St. Yd. Mn -10%
WS Q1 - St.Yd. Mn +10%
Ground
138
136
134
0
50
100
150
200
250
300
350
Plan:
1) St.Yd. Existing
Byr Brook 3
10/11/2014
2) St. Yd. WCe +10%
09/11/2014
3) St. Yd. WCe -10%
09/11/2014
Byr Brook 1
Unnamed Trib. 2
144
Legend
WS Q1000 - St. Yd. WCe +10%
WS Q1000 - St. Yd. WCe -10%
WS Q100+CCA - St. Yd. WCe +10%
142
WS Q100+CCA - St. Yd. WCe -10%
WS Q100 - St. Yd. WCe -10%
WS Q100 - St. Yd. WCe +10%
140
Elevation (m)
WS Q1 - St. Yd. WCe +10%
WS Q1 - St. Yd. WCe -10%
Ground
138
136
134
0
50
100
150
200
250
300
350
HEC-RAS Profile: Q100+CCA
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
200
200
200
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
1.80
1.80
1.80
141.96
141.96
141.96
142.69
142.69
142.69
142.69
142.69
142.69
142.95
142.95
142.95
0.003123
0.003123
0.003123
2.49
2.49
2.49
1.94
1.94
1.94
5.23
5.23
5.23
0.97
0.97
0.97
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
200
200
200
200
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
1.80
1.80
1.80
1.80
141.96
141.96
141.96
141.96
142.69
142.69
142.70
142.70
142.69
142.69
142.70
142.70
142.95
142.95
142.95
142.95
0.003123
0.003123
0.003827
0.002420
2.49
2.49
2.47
2.49
1.94
1.94
1.95
1.95
5.23
5.23
5.25
5.25
0.97
0.97
0.96
0.96
Unnamed Trib.
Unnamed Trib.
2
2
200
200
Q100+CCA
Q100+CCA
St. Yd. WCe +10%
St. Yd. WCe -10%
1.80
1.80
141.96
141.96
142.69
142.69
142.69
142.69
142.95
142.95
0.003123
0.003123
2.49
2.49
1.94
1.94
5.23
5.23
0.97
0.97
Unnamed Trib.
Unnamed Trib.
2
2
184.87
184.87
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
1.80
1.80
141.43
141.43
141.93
141.93
141.93
141.93
142.13
142.13
0.003790
0.003790
1.99
1.99
1.12
1.12
3.70
3.70
0.99
0.99
Unnamed Trib.
2
184.87
Q100+CCA
+20% S.Depth
1.80
141.43
141.93
141.93
142.13
0.003790
1.99
1.12
3.70
0.99
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
2
2
184.87
184.87
184.87
184.87
184.87
184.87
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
1.80
1.80
1.80
1.80
1.80
1.80
141.43
141.43
141.43
141.43
141.43
141.43
141.93
141.93
141.93
141.93
141.93
141.93
141.93
141.93
141.93
141.93
141.93
141.93
142.13
142.13
142.13
142.13
142.13
142.13
0.003790
0.003790
0.004730
0.002953
0.003790
0.003790
1.99
1.99
1.98
1.99
1.99
1.99
1.12
1.12
1.12
1.12
1.12
1.12
3.70
3.70
3.70
3.70
3.70
3.70
0.99
0.99
0.99
0.99
0.99
0.99
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
2
2
2
2
2
182.862
182.862
182.862
182.862
182.862
182.862
182.862
182.862
182.862
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
140.94
140.94
140.94
140.94
140.94
140.94
140.94
140.94
140.94
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
142.06
142.06
142.06
142.06
142.06
142.06
142.06
142.06
142.06
0.005462
0.005462
0.005462
0.005462
0.005462
0.006817
0.004258
0.005462
0.005462
2.14
2.14
2.14
2.14
2.14
2.14
2.15
2.14
2.14
0.92
0.92
0.92
0.92
0.92
0.92
0.92
0.92
0.92
2.80
2.80
2.80
2.80
2.80
2.80
2.80
2.80
2.80
0.97
0.97
0.97
0.97
0.97
0.97
0.97
0.97
0.97
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
2
2
2
2
2
180.942
180.942
180.942
180.942
180.942
180.942
180.942
180.942
180.942
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
140.82
140.82
140.82
140.82
140.82
140.82
140.82
140.82
140.82
141.70
141.70
141.70
141.70
141.70
141.70
141.70
141.70
141.70
141.73
141.73
141.73
141.73
141.73
141.73
141.73
141.73
141.73
0.000248
0.000248
0.000248
0.000248
0.000248
0.000308
0.000192
0.000248
0.000248
0.73
0.73
0.73
0.73
0.73
0.73
0.73
0.73
0.73
2.80
2.80
2.80
2.80
2.80
2.80
2.80
2.80
2.80
4.72
4.72
4.72
4.72
4.72
4.73
4.73
4.72
4.72
0.28
0.28
0.28
0.28
0.28
0.28
0.28
0.28
0.28
Unnamed Trib.
Unnamed Trib.
2
2
176.548
176.548
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
1.80
1.80
140.40
140.40
141.67
141.67
141.72
141.72
0.000386
0.000386
1.14
1.14
3.73
3.73
5.92
5.92
0.34
0.34
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
176.548
176.548
176.548
Q100+CCA
Q100+CCA
Q100+CCA
+20% S.Depth
-20% S.Depth
St.Yd. Existing
1.80
1.80
1.80
140.40
140.40
140.40
141.67
141.67
141.67
141.72
141.72
141.72
0.000386
0.000386
0.000386
1.14
1.14
1.14
3.73
3.73
3.73
5.92
5.92
5.92
0.34
0.34
0.34
HEC-RAS Profile: Q100+CCA (Continued)
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
176.548
176.548
176.548
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
1.80
1.80
1.80
140.40
140.40
140.40
141.67
141.67
141.67
141.72
141.72
141.72
0.000478
0.000301
0.000386
1.13
1.14
1.14
3.74
3.73
3.73
5.93
5.93
5.92
0.34
0.34
0.34
Unnamed Trib.
2
176.548
Q100+CCA
St. Yd. WCe -10%
1.80
140.40
141.67
141.72
0.000386
1.14
3.73
5.92
0.34
Unnamed Trib.
Unnamed Trib.
2
2
165.156
165.156
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
1.80
1.80
140.07
140.07
141.25
141.25
141.25
141.25
141.67
141.67
0.004113
0.004113
3.03
3.03
1.19
1.19
1.94
1.94
0.95
0.95
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
2
165.156
165.156
165.156
165.156
165.156
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
1.80
1.80
1.80
1.80
1.80
140.07
140.07
140.07
140.07
140.07
141.25
141.25
141.25
141.25
141.24
141.25
141.25
141.25
141.25
141.24
141.67
141.67
141.67
141.67
141.68
0.004113
0.004113
0.004113
0.005162
0.003300
3.03
3.03
3.03
3.04
3.06
1.19
1.19
1.19
1.18
1.17
1.94
1.94
1.94
1.93
1.92
0.95
0.95
0.95
0.95
0.96
Unnamed Trib.
2
165.156
Q100+CCA
St. Yd. WCe +10%
1.80
140.07
141.25
141.25
141.67
0.004113
3.03
1.19
1.94
0.95
Unnamed Trib.
2
165.156
Q100+CCA
St. Yd. WCe -10%
1.80
140.07
141.25
141.25
141.67
0.004113
3.03
1.19
1.94
0.95
Unnamed Trib.
2
164.156
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
2
2
2
2
2
121.355
121.355
121.355
121.355
121.355
121.355
121.355
121.355
121.355
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
138.53
138.53
138.53
138.53
138.53
138.53
138.53
138.53
138.53
140.38
140.38
140.38
140.38
140.38
140.38
140.38
140.40
140.37
140.38
140.38
140.38
140.38
140.38
140.38
140.38
140.40
140.37
0.000007
0.000007
0.000007
0.000007
0.000007
0.000009
0.000006
0.000007
0.000008
0.17
0.17
0.17
0.17
0.17
0.17
0.17
0.17
0.18
10.35
10.35
10.35
10.35
10.35
10.36
10.35
10.44
10.28
5.75
5.75
5.75
5.75
5.75
5.75
5.75
5.75
5.75
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
1
1
1
1
1
500
500
500
500
500
500
500
500
500
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
5.40
5.40
5.40
5.40
5.40
5.40
5.40
5.40
5.40
141.20
141.20
141.20
141.20
141.20
141.20
141.20
141.20
141.20
143.04
143.04
143.04
143.04
143.04
143.05
143.04
143.05
143.04
143.08
143.08
143.08
143.08
143.08
143.08
143.07
143.08
143.07
0.000196
0.000196
0.000196
0.000196
0.000196
0.000243
0.000155
0.000193
0.000198
0.83
0.83
0.83
0.83
0.83
0.83
0.83
0.83
0.83
6.69
6.69
6.69
6.69
6.69
6.71
6.65
6.73
6.67
6.21
6.21
6.21
6.21
6.21
6.23
6.19
6.24
6.21
0.22
0.22
0.22
0.22
0.22
0.22
0.22
0.22
0.22
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
1
486.70
486.70
486.70
486.70
486.70
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
5.40
5.40
5.40
5.40
5.40
141.09
141.09
141.09
141.09
141.09
143.05
143.05
143.05
143.05
143.05
143.07
143.07
143.07
143.07
143.07
0.000103
0.000103
0.000103
0.000103
0.000103
0.64
0.64
0.64
0.64
0.64
8.43
8.43
8.43
8.43
8.43
5.18
5.18
5.18
5.18
5.18
0.16
0.16
0.16
0.16
0.16
Byr Brook
Byr Brook
Byr Brook
1
1
1
486.70
486.70
486.70
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
5.40
5.40
5.40
141.09
141.09
141.09
143.05
143.05
143.06
143.07
143.07
143.08
0.000128
0.000081
0.000102
0.64
0.64
0.64
8.45
8.41
8.47
5.19
5.17
5.20
0.16
0.16
0.16
Culvert
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Byr Brook
1
486.70
Q100+CCA
St. Yd. WCe -10%
5.40
141.09
143.05
Byr Brook
1
477.04
Q100+CCA
+20% Flow
5.40
140.69
142.78
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
477.04
477.04
477.04
477.04
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
5.40
5.40
5.40
5.40
140.69
140.69
140.69
140.69
142.78
142.78
142.78
142.78
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
477.04
477.04
477.04
477.04
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
5.40
5.40
5.40
5.40
140.69
140.69
140.69
140.69
Byr Brook
1
473.49
Q100+CCA
+20% Flow
5.40
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
1
1
1
1
473.49
473.49
473.49
473.49
473.49
473.49
473.49
473.49
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
5.40
5.40
5.40
5.40
5.40
5.40
5.40
5.40
Byr Brook
1
472.49
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
1
1
1
1
1
367.94
367.94
367.94
367.94
367.94
367.94
367.94
367.94
367.94
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
3
3
3
3
364.253
364.253
364.253
364.253
364.253
364.253
364.253
364.253
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Byr Brook
3
364.253
Byr Brook
3
360.566
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
143.07
0.000103
0.64
8.42
5.17
0.16
142.35
143.04
0.003962
2.30
2.66
4.47
0.61
142.35
142.35
142.35
142.35
143.04
143.04
143.04
143.04
0.003962
0.003962
0.003962
0.003962
2.30
2.30
2.30
2.30
2.66
2.66
2.66
2.66
4.47
4.47
4.47
4.47
0.61
0.61
0.61
0.61
142.78
142.77
142.79
142.77
142.35
142.35
142.35
142.35
143.05
143.04
143.05
143.04
0.004878
0.003152
0.003832
0.004009
2.29
2.31
2.27
2.31
2.69
2.63
2.72
2.64
4.48
4.47
4.49
4.47
0.60
0.61
0.60
0.61
140.66
142.75
142.10
143.03
0.004127
2.34
2.61
4.59
0.54
140.66
140.66
140.66
140.66
140.66
140.66
140.66
140.66
142.75
142.75
142.75
142.75
142.75
142.75
142.76
142.74
142.10
142.10
142.10
142.10
142.10
142.10
142.10
142.10
143.03
143.03
143.03
143.03
143.03
143.03
143.03
143.02
0.004127
0.004127
0.004127
0.004127
0.005134
0.003227
0.004025
0.004163
2.34
2.34
2.34
2.34
2.34
2.35
2.32
2.35
2.61
2.61
2.61
2.61
2.62
2.60
2.67
2.59
4.59
4.59
4.59
4.59
4.59
4.59
4.59
4.56
0.54
0.54
0.54
0.54
0.54
0.54
0.53
0.54
5.40
5.40
5.40
5.40
5.40
5.40
5.40
5.40
5.40
138.56
138.56
138.56
138.56
138.56
138.56
138.56
138.56
138.56
140.30
140.30
140.30
140.30
140.30
140.30
140.30
140.32
140.29
140.38
140.38
140.38
140.38
140.38
140.38
140.38
140.39
140.36
0.000589
0.000589
0.000589
0.000589
0.000589
0.000735
0.000459
0.000570
0.000606
1.22
1.22
1.22
1.22
1.22
1.21
1.22
1.20
1.23
4.44
4.44
4.44
4.44
4.44
4.45
4.44
4.50
4.40
3.24
3.24
3.24
3.24
3.24
3.25
3.24
3.26
3.23
0.33
0.33
0.33
0.33
0.33
0.33
0.33
0.33
0.34
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
7.20
7.20
7.20
7.20
7.20
7.20
7.20
7.20
138.56
138.56
138.56
138.56
138.56
138.56
138.56
138.56
140.22
140.22
140.22
140.22
140.22
140.22
140.22
140.24
140.37
140.37
140.37
140.37
140.37
140.37
140.37
140.38
0.001239
0.001239
0.001239
0.001239
0.001239
0.001546
0.000966
0.001189
1.73
1.73
1.73
1.73
1.73
1.73
1.73
1.70
4.17
4.17
4.17
4.17
4.17
4.17
4.17
4.23
3.18
3.18
3.18
3.18
3.18
3.18
3.18
3.20
0.48
0.48
0.48
0.48
0.48
0.48
0.48
0.47
Q100+CCA
St. Yd. WCe -10%
7.20
138.56
140.20
140.36
0.001283
1.75
4.11
3.17
0.49
Q100+CCA
+20% Flow
7.20
138.37
140.26
140.34
0.000510
1.24
5.79
4.12
0.33
Culvert
139.39
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
Byr Brook
Byr Brook
Byr Brook
3
3
3
360.566
360.566
360.566
Q100+CCA
Q100+CCA
Q100+CCA
-20% Flow
+20% S.Depth
-20% S.Depth
7.20
7.20
7.20
138.37
138.37
138.37
140.26
140.26
140.26
139.39
139.39
139.39
140.34
140.34
140.34
0.000510
0.000510
0.000510
1.24
1.24
1.24
5.79
5.79
5.79
4.12
4.12
4.12
0.33
0.33
0.33
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
360.566
360.566
360.566
360.566
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
7.20
7.20
7.20
7.20
138.37
138.37
138.37
138.37
140.26
140.26
140.26
140.28
139.39
139.39
139.39
139.39
140.34
140.34
140.34
140.36
0.000510
0.000638
0.000397
0.000492
1.24
1.24
1.24
1.23
5.79
5.79
5.79
5.87
4.12
4.12
4.12
4.14
0.33
0.33
0.33
0.33
Byr Brook
3
360.566
Q100+CCA
St. Yd. WCe -10%
7.20
138.37
140.25
139.39
140.33
0.000526
1.26
5.73
4.11
0.34
Byr Brook
3
359.566
Byr Brook
3
239.269
Q100+CCA
+20% Flow
7.20
136.28
138.28
138.28
138.79
0.007239
3.15
2.29
2.36
1.00
Byr Brook
3
239.269
Q100+CCA
-20% Flow
7.20
136.28
138.28
138.28
138.79
0.007239
3.15
2.29
2.36
1.00
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
3
3
3
239.269
239.269
239.269
239.269
239.269
239.269
239.269
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
7.20
7.20
7.20
7.20
7.20
7.20
7.20
136.28
136.28
136.28
136.28
136.28
136.28
136.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.79
138.79
138.79
138.79
138.79
138.79
138.79
0.007239
0.007239
0.007239
0.009042
0.005636
0.007239
0.007239
3.15
3.15
3.15
3.15
3.15
3.15
3.15
2.29
2.29
2.29
2.29
2.29
2.29
2.29
2.36
2.36
2.36
2.36
2.36
2.36
2.36
1.00
1.00
1.00
1.00
1.00
1.00
1.00
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
3
3
3
3
3
232.359
232.359
232.359
232.359
232.359
232.359
232.359
232.359
232.359
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
7.20
7.20
7.20
7.20
7.20
7.20
7.20
7.20
7.20
136.35
136.35
136.35
136.35
136.35
136.35
136.35
136.35
136.35
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.20
137.51
137.51
137.51
137.51
137.51
137.51
137.51
137.51
137.51
0.003991
0.003991
0.003991
0.003991
0.003991
0.004985
0.003107
0.003991
0.003991
2.47
2.47
2.47
2.47
2.47
2.47
2.47
2.47
2.47
2.92
2.92
2.92
2.92
2.92
2.92
2.92
2.92
2.92
4.77
4.77
4.77
4.77
4.77
4.77
4.77
4.77
4.77
1.01
1.01
1.01
1.01
1.01
1.01
1.01
1.01
1.01
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
3
3
3
3
3
206.209
206.209
206.209
206.209
206.209
206.209
206.209
206.209
206.209
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
+20% Flow
-20% Flow
+20% S.Depth
-20% S.Depth
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
St. Yd. WCe +10%
St. Yd. WCe -10%
7.20
7.20
7.20
7.20
7.20
7.20
7.20
7.20
7.20
135.96
135.96
135.96
135.96
135.96
135.96
135.96
135.96
135.96
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
137.12
137.12
137.12
137.12
137.12
137.12
137.12
137.12
137.12
0.003640
0.003640
0.003640
0.003640
0.003640
0.004544
0.002836
0.003640
0.003640
2.54
2.54
2.54
2.54
2.54
2.54
2.54
2.54
2.54
3.11
3.11
3.11
3.11
3.11
3.11
3.11
3.11
3.11
7.25
7.25
7.25
7.25
7.25
7.26
7.25
7.25
7.25
0.98
0.98
0.98
0.98
0.98
0.98
0.98
0.98
0.98
Byr Brook
3
184.716
Q100+CCA
+20% Flow
7.20
135.46
136.26
136.26
136.62
0.003374
2.65
2.85
4.36
1.00
Byr Brook
Byr Brook
Byr Brook
3
3
3
184.716
184.716
184.716
Q100+CCA
Q100+CCA
Q100+CCA
-20% Flow
+20% S.Depth
-20% S.Depth
7.20
7.20
7.20
135.46
135.46
135.46
136.26
136.26
136.26
136.26
136.26
136.26
136.62
136.62
136.62
0.003377
0.003377
0.003377
2.65
2.65
2.65
2.84
2.84
2.84
4.36
4.36
4.36
1.00
1.00
1.00
Culvert
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
Byr Brook
Byr Brook
Byr Brook
3
3
3
184.716
184.716
184.716
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. Mn +10%
St. Yd. Mn -10%
7.20
7.20
7.20
135.46
135.46
135.46
136.26
136.26
136.26
136.26
136.26
136.26
136.62
136.62
136.62
0.003377
0.004211
0.002629
2.65
2.65
2.65
2.84
2.85
2.84
4.36
4.36
4.36
1.00
1.00
1.00
Byr Brook
Byr Brook
3
3
184.716
184.716
Q100+CCA
Q100+CCA
St. Yd. WCe +10%
St. Yd. WCe -10%
7.20
7.20
135.46
135.46
136.26
136.26
136.26
136.26
136.62
136.62
0.003377
0.003377
2.65
2.65
2.84
2.84
4.36
4.36
1.00
1.00
APPENDIX U:
1D MODELLING BLOCKAGE SCENARIOS OUTPUTS
FRA262 – FCA
206.209
232.359
239.269
200
184.87
166.156
Un
na
me
d
Tr
By
3
ib
ok
367.94
121.355
Junc.1
1
By
r B
r oo
k
2
.
r
o
Br
474.49
486.70
500
184.716
HEC-RAS Profile: Q100+CCA
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
2
2
2
2
2
200
200
200
200
200
200
200
200
200
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
141.96
141.96
141.96
141.96
141.96
141.96
141.96
141.96
141.96
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.69
142.95
142.95
142.95
142.95
142.95
142.95
142.95
142.95
142.95
0.003123
0.003123
0.003123
0.003123
0.003123
0.003123
0.003123
0.003123
0.003123
2.49
2.49
2.49
2.49
2.49
2.49
2.49
2.49
2.49
1.94
1.94
1.94
1.94
1.94
1.94
1.94
1.94
1.94
5.23
5.23
5.23
5.23
5.23
5.23
5.23
5.23
5.23
0.97
0.97
0.97
0.97
0.97
0.97
0.97
0.97
0.97
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
184.87
184.87
184.87
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
St.Yd. C2 B75%
1.80
1.80
1.80
141.43
141.43
141.43
141.93
141.93
141.93
141.93
141.93
141.93
142.13
142.13
142.13
0.003790
0.003790
0.003790
1.99
1.99
1.99
1.12
1.12
1.12
3.70
3.70
3.70
0.99
0.99
0.99
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
184.87
184.87
184.87
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
1.80
1.80
1.80
141.43
141.43
141.43
141.93
141.93
141.93
141.93
141.93
141.93
142.13
142.13
142.13
0.003790
0.003790
0.003790
1.99
1.99
1.99
1.12
1.12
1.12
3.70
3.70
3.70
0.99
0.99
0.99
Unnamed Trib.
2
184.87
Q100+CCA
St. Yd. C3 B25%
1.80
141.43
141.93
141.93
142.13
0.003790
1.99
1.12
3.70
0.99
Unnamed Trib.
Unnamed Trib.
2
2
184.87
184.87
Q100+CCA
Q100+CCA
St.Yd. B AC 25%
St.Yd. B AC 75%
1.80
1.80
141.43
141.43
141.93
141.93
141.93
141.93
142.13
142.13
0.003790
0.003790
1.99
1.99
1.12
1.12
3.70
3.70
0.99
0.99
Unnamed Trib.
Unnamed Trib.
2
2
182.862
182.862
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
1.80
1.80
140.94
140.94
141.82
141.82
141.82
141.82
142.06
142.06
0.005462
0.005462
2.14
2.14
0.92
0.92
2.80
2.80
0.97
0.97
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
182.862
182.862
182.862
182.862
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
1.80
1.80
1.80
1.80
140.94
140.94
140.94
140.94
141.82
141.82
141.82
141.82
141.82
141.82
141.82
141.82
142.06
142.06
142.06
142.06
0.005462
0.005536
0.005462
0.005462
2.14
2.15
2.14
2.14
0.92
0.91
0.92
0.92
2.80
2.79
2.80
2.80
0.97
0.98
0.97
0.97
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
182.862
182.862
182.862
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
1.80
1.80
1.80
140.94
140.94
140.94
141.82
141.82
141.82
141.82
141.82
141.82
142.06
142.06
142.06
0.005536
0.005536
0.005536
2.15
2.15
2.15
0.91
0.91
0.91
2.79
2.79
2.79
0.98
0.98
0.98
Unnamed Trib.
Unnamed Trib.
2
2
180.942
180.942
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
1.80
1.80
140.82
140.82
141.70
141.70
141.73
141.73
0.000248
0.000248
0.73
0.73
2.80
2.80
4.72
4.72
0.28
0.28
Unnamed Trib.
Unnamed Trib.
2
2
180.942
180.942
Q100+CCA
Q100+CCA
St.Yd. C2 B75%
St.Yd. C3 B75%
1.80
1.80
140.82
140.82
141.70
141.65
141.73
141.68
0.000248
0.000314
0.73
0.78
2.80
2.57
4.72
4.61
0.28
0.31
Unnamed Trib.
Unnamed Trib.
2
2
180.942
180.942
Q100+CCA
Q100+CCA
St. Yd. C1 B25%
St. Yd. C2 B25%
1.80
1.80
140.82
140.82
141.70
141.70
141.73
141.73
0.000248
0.000248
0.73
0.73
2.80
2.80
4.72
4.72
0.28
0.28
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
180.942
180.942
180.942
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
1.80
1.80
1.80
140.82
140.82
140.82
141.65
141.65
141.65
141.68
141.68
141.68
0.000314
0.000314
0.000314
0.78
0.78
0.78
2.57
2.57
2.57
4.61
4.61
4.61
0.31
0.31
0.31
Unnamed Trib.
Unnamed Trib.
2
2
176.548
176.548
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
1.80
1.80
140.40
140.40
141.67
141.67
141.72
141.72
0.000386
0.000386
1.14
1.14
3.73
3.73
5.92
5.92
0.34
0.34
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
2
2
2
176.548
176.548
176.548
176.548
176.548
176.548
176.548
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
1.80
1.80
1.80
1.80
1.80
1.80
1.80
140.40
140.40
140.40
140.40
140.40
140.40
140.40
141.67
141.61
141.67
141.67
141.61
141.61
141.61
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
2
165.156
165.156
165.156
165.156
165.156
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
1.80
1.80
1.80
1.80
1.80
140.07
140.07
140.07
140.07
140.07
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
165.156
165.156
165.156
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
1.80
1.80
1.80
Unnamed Trib.
2
165.156
Q100+CCA
St.Yd. B AC 75%
1.80
Unnamed Trib.
2
164.156
Unnamed Trib.
Unnamed Trib.
2
2
121.355
121.355
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
121.355
121.355
121.355
121.355
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
121.355
121.355
121.355
Byr Brook
Byr Brook
1
1
Byr Brook
Byr Brook
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
141.14
141.14
141.14
141.72
141.68
141.72
141.72
141.68
141.68
141.68
0.000386
0.000460
0.000386
0.000386
0.000460
0.000460
0.000460
1.14
1.20
1.14
1.14
1.20
1.20
1.20
3.73
3.43
3.73
3.73
3.43
3.43
3.43
5.92
5.68
5.92
5.92
5.68
5.68
5.68
0.34
0.37
0.34
0.34
0.37
0.37
0.37
141.25
141.25
141.25
141.25
141.25
141.25
141.25
141.25
141.25
141.25
141.67
141.67
141.67
141.67
141.67
0.004113
0.004113
0.004113
0.004113
0.004113
3.03
3.03
3.03
3.03
3.03
1.19
1.19
1.19
1.19
1.19
1.94
1.94
1.94
1.94
1.94
0.95
0.95
0.95
0.95
0.95
140.07
140.07
140.07
141.25
141.25
141.25
141.25
141.25
141.25
141.67
141.67
141.67
0.004113
0.004113
0.004113
3.03
3.03
3.03
1.19
1.19
1.19
1.94
1.94
1.94
0.95
0.95
0.95
140.07
141.25
141.25
141.67
0.004113
3.03
1.19
1.94
0.95
1.80
1.80
138.53
138.53
140.38
140.38
140.38
140.38
0.000007
0.000007
0.17
0.17
10.35
10.35
5.75
5.75
0.04
0.04
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
1.80
1.80
1.80
1.80
138.53
138.53
138.53
138.53
140.42
140.38
140.38
140.42
140.42
140.38
140.38
140.42
0.000007
0.000007
0.000007
0.000007
0.17
0.17
0.17
0.17
10.57
10.35
10.35
10.57
5.75
5.75
5.75
5.75
0.04
0.04
0.04
0.04
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
1.80
1.80
1.80
138.53
138.53
138.53
140.38
140.42
140.42
140.38
140.42
140.42
0.000007
0.000007
0.000007
0.17
0.17
0.17
10.35
10.57
10.57
5.75
5.75
5.75
0.04
0.04
0.04
500
500
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
5.40
5.40
141.20
141.20
143.04
143.04
143.08
143.07
0.000196
0.000198
0.83
0.83
6.69
6.66
6.21
6.20
0.22
0.22
1
1
500
500
Q100+CCA
Q100+CCA
St.Yd. C2 B75%
St.Yd. C3 B75%
5.40
5.40
141.20
141.20
143.04
143.04
143.07
143.08
0.000198
0.000196
0.83
0.83
6.67
6.69
6.20
6.21
0.22
0.22
Byr Brook
Byr Brook
1
1
500
500
Q100+CCA
Q100+CCA
St. Yd. C1 B25%
St. Yd. C2 B25%
5.40
5.40
141.20
141.20
143.04
143.04
143.07
143.07
0.000199
0.000198
0.84
0.83
6.65
6.67
6.19
6.20
0.22
0.22
Byr Brook
Byr Brook
Byr Brook
1
1
1
500
500
500
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
5.40
5.40
5.40
141.20
141.20
141.20
143.04
143.03
143.03
143.08
143.07
143.07
0.000196
0.000201
0.000200
0.83
0.84
0.84
6.69
6.63
6.64
6.21
6.17
6.19
0.22
0.23
0.23
Byr Brook
Byr Brook
1
1
486.70
486.70
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
5.40
5.40
141.09
141.09
143.05
143.05
143.07
143.07
0.000103
0.000104
0.64
0.64
8.43
8.41
5.18
5.17
0.16
0.16
141.14
Culvert
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
1
1
1
486.70
486.70
486.70
486.70
486.70
486.70
486.70
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
5.40
5.40
5.40
5.40
5.40
5.40
5.40
141.09
141.09
141.09
141.09
141.09
141.09
141.09
143.05
143.05
143.04
143.05
143.05
143.04
143.04
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
1
477.04
477.04
477.04
477.04
477.04
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
5.40
5.40
5.40
5.40
5.40
140.69
140.69
140.69
140.69
140.69
142.78
142.77
142.77
142.78
142.77
Byr Brook
Byr Brook
Byr Brook
1
1
1
477.04
477.04
477.04
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
5.40
5.40
5.40
140.69
140.69
140.69
Byr Brook
1
477.04
Q100+CCA
St.Yd. B AC 75%
5.40
Byr Brook
1
473.49
Q100+CCA
St.Yd. Existing
Byr Brook
Byr Brook
Byr Brook
1
1
1
473.49
473.49
473.49
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. C1 B75%
St.Yd. C2 B75%
St.Yd. C3 B75%
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
473.49
473.49
473.49
473.49
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Byr Brook
1
473.49
Q100+CCA
Byr Brook
1
472.49
Byr Brook
Byr Brook
1
1
367.94
367.94
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
Byr Brook
Byr Brook
1
1
367.94
367.94
Q100+CCA
Q100+CCA
Byr Brook
Byr Brook
1
1
367.94
367.94
Byr Brook
Byr Brook
Byr Brook
1
1
1
Byr Brook
Byr Brook
3
3
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
143.07
143.07
143.07
143.07
143.07
143.06
143.06
0.000104
0.000103
0.000104
0.000104
0.000103
0.000105
0.000104
0.64
0.64
0.64
0.64
0.64
0.64
0.64
8.42
8.43
8.40
8.42
8.43
8.39
8.40
5.17
5.18
5.17
5.17
5.18
5.17
5.17
0.16
0.16
0.16
0.16
0.16
0.16
0.16
142.35
142.35
142.35
142.35
142.35
143.04
143.04
143.04
143.04
143.04
0.003962
0.004042
0.004021
0.003962
0.004079
2.30
2.31
2.31
2.30
2.32
2.66
2.63
2.64
2.66
2.61
4.47
4.47
4.47
4.47
4.47
0.61
0.61
0.61
0.61
0.62
142.77
142.78
142.76
142.35
142.35
142.35
143.04
143.04
143.03
0.004021
0.003962
0.004136
2.31
2.30
2.33
2.64
2.66
2.59
4.47
4.47
4.46
0.61
0.61
0.62
140.69
142.76
142.35
143.04
0.004099
2.32
2.60
4.46
0.62
5.40
140.66
142.75
142.10
143.03
0.004127
2.34
2.61
4.59
0.54
5.40
5.40
5.40
140.66
140.66
140.66
142.75
142.74
142.75
142.10
142.10
142.10
143.03
143.02
143.03
0.004127
0.004172
0.004127
2.34
2.35
2.34
2.61
2.58
2.61
4.59
4.53
4.59
0.54
0.54
0.54
St. Yd. C1 B25%
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
5.40
5.40
5.40
5.40
140.66
140.66
140.66
140.66
142.75
142.74
142.75
142.74
142.10
142.10
142.10
142.10
143.03
143.02
143.03
143.02
0.004127
0.004172
0.004127
0.004172
2.34
2.35
2.34
2.35
2.61
2.58
2.61
2.58
4.59
4.53
4.59
4.53
0.54
0.54
0.54
0.54
St.Yd. B AC 75%
5.40
140.66
142.74
142.10
143.02
0.004172
2.35
2.58
4.53
0.54
5.40
5.40
138.56
138.56
140.30
140.30
140.38
140.38
0.000589
0.000589
1.22
1.22
4.44
4.44
3.24
3.24
0.33
0.33
St.Yd. C2 B75%
St.Yd. C3 B75%
5.40
5.40
138.56
138.56
140.34
140.30
140.41
140.38
0.000543
0.000589
1.18
1.22
4.58
4.44
3.28
3.24
0.32
0.33
Q100+CCA
Q100+CCA
St. Yd. C1 B25%
St. Yd. C2 B25%
5.40
5.40
138.56
138.56
140.30
140.34
140.38
140.41
0.000589
0.000543
1.22
1.18
4.44
4.58
3.24
3.28
0.33
0.32
367.94
367.94
367.94
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
5.40
5.40
5.40
138.56
138.56
138.56
140.30
140.34
140.34
140.38
140.41
140.41
0.000589
0.000543
0.000543
1.22
1.18
1.18
4.44
4.58
4.58
3.24
3.28
3.28
0.33
0.32
0.32
364.253
364.253
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
7.20
7.20
138.56
138.56
140.22
140.22
140.37
140.37
0.001239
0.001239
1.73
1.73
4.17
4.17
3.18
3.18
0.48
0.48
Culvert
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Crit W.S.
(m)
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
3
3
3
364.253
364.253
364.253
364.253
364.253
364.253
364.253
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
7.20
7.20
7.20
7.20
7.20
7.20
7.20
138.56
138.56
138.56
138.56
138.56
138.56
138.56
140.27
140.22
140.22
140.27
140.22
140.27
140.27
139.64
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
3
360.566
360.566
360.566
360.566
360.566
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
7.20
7.20
7.20
7.20
7.20
138.37
138.37
138.37
138.37
138.37
Byr Brook
Byr Brook
Byr Brook
3
3
3
360.566
360.566
360.566
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
7.20
7.20
7.20
Byr Brook
3
360.566
Q100+CCA
St.Yd. B AC 75%
7.20
Byr Brook
3
359.566
Byr Brook
Byr Brook
3
3
239.269
239.269
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
239.269
239.269
239.269
239.269
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Byr Brook
Byr Brook
Byr Brook
3
3
3
239.269
239.269
239.269
Byr Brook
Byr Brook
3
3
Byr Brook
Byr Brook
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
139.64
139.64
140.41
140.37
140.37
140.41
140.37
140.41
140.41
0.001122
0.001239
0.001239
0.001122
0.001239
0.001122
0.001122
1.66
1.73
1.73
1.66
1.73
1.66
1.66
4.33
4.17
4.17
4.33
4.17
4.33
4.33
3.22
3.18
3.18
3.22
3.18
3.22
3.22
0.46
0.48
0.48
0.46
0.48
0.46
0.46
140.26
140.26
140.26
140.26
140.26
139.39
139.39
139.39
139.39
139.39
140.34
140.34
140.34
140.34
140.34
0.000510
0.000510
0.000510
0.000510
0.000510
1.24
1.24
1.24
1.24
1.24
5.79
5.79
5.79
5.79
5.79
4.12
4.12
4.12
4.12
4.12
0.33
0.33
0.33
0.33
0.33
138.37
138.37
138.37
140.26
140.26
140.26
139.39
139.39
139.39
140.34
140.34
140.34
0.000510
0.000510
0.000510
1.24
1.24
1.24
5.79
5.79
5.79
4.12
4.12
4.12
0.33
0.33
0.33
138.37
140.26
139.39
140.34
0.000510
1.24
5.79
4.12
0.33
7.20
7.20
136.28
136.28
138.28
138.28
138.28
138.28
138.79
138.79
0.007239
0.007239
3.15
3.15
2.29
2.29
2.36
2.36
1.00
1.00
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
7.20
7.20
7.20
7.20
136.28
136.28
136.28
136.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.28
138.79
138.79
138.79
138.79
0.007239
0.007239
0.007239
0.007239
3.15
3.15
3.15
3.15
2.29
2.29
2.29
2.29
2.36
2.36
2.36
2.36
1.00
1.00
1.00
1.00
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
7.20
7.20
7.20
136.28
136.28
136.28
138.28
138.28
138.28
138.28
138.28
138.28
138.79
138.79
138.79
0.007239
0.007239
0.007239
3.15
3.15
3.15
2.29
2.29
2.29
2.36
2.36
2.36
1.00
1.00
1.00
232.359
232.359
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
7.20
7.20
136.35
136.35
137.20
137.20
137.20
137.20
137.51
137.51
0.003991
0.003991
2.47
2.47
2.92
2.92
4.77
4.77
1.01
1.01
3
3
232.359
232.359
Q100+CCA
Q100+CCA
St.Yd. C2 B75%
St.Yd. C3 B75%
7.20
7.20
136.35
136.35
137.20
137.20
137.20
137.20
137.51
137.51
0.003991
0.003991
2.47
2.47
2.92
2.92
4.77
4.77
1.01
1.01
Byr Brook
Byr Brook
3
3
232.359
232.359
Q100+CCA
Q100+CCA
St. Yd. C1 B25%
St. Yd. C2 B25%
7.20
7.20
136.35
136.35
137.20
137.20
137.20
137.20
137.51
137.51
0.003991
0.003991
2.47
2.47
2.92
2.92
4.77
4.77
1.01
1.01
Byr Brook
Byr Brook
Byr Brook
3
3
3
232.359
232.359
232.359
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
7.20
7.20
7.20
136.35
136.35
136.35
137.20
137.20
137.20
137.20
137.20
137.20
137.51
137.51
137.51
0.003991
0.003991
0.003991
2.47
2.47
2.47
2.92
2.92
2.92
4.77
4.77
4.77
1.01
1.01
1.01
Byr Brook
Byr Brook
3
3
206.209
206.209
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
7.20
7.20
135.96
135.96
136.79
136.79
136.79
136.79
137.12
137.12
0.003640
0.003640
2.54
2.54
3.11
3.11
7.25
7.25
0.98
0.98
139.64
Culvert
River
Reach
River Sta
Profile
Plan
Q Total
(m3/s)
Min Ch El
(m)
W.S. Elev
(m)
Crit W.S.
(m)
E.G. Elev
(m)
E.G. Slope
(m/m)
Vel Chnl
(m/s)
Flow Area
(m2)
Top Width
(m)
Froude # Chl
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
3
3
3
206.209
206.209
206.209
206.209
206.209
206.209
206.209
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
St.Yd. B AC 75%
7.20
7.20
7.20
7.20
7.20
7.20
7.20
135.96
135.96
135.96
135.96
135.96
135.96
135.96
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
136.79
137.12
137.12
137.12
137.12
137.12
137.12
137.12
0.003640
0.003640
0.003640
0.003640
0.003640
0.003640
0.003640
2.54
2.54
2.54
2.54
2.54
2.54
2.54
3.11
3.11
3.11
3.11
3.11
3.11
3.11
7.25
7.25
7.25
7.25
7.25
7.25
7.25
0.98
0.98
0.98
0.98
0.98
0.98
0.98
Byr Brook
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
3
184.716
184.716
184.716
184.716
184.716
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
Q100+CCA
St.Yd. Existing
St.Yd. C1 B75%
St.Yd. C2 B75%
St.Yd. C3 B75%
St. Yd. C1 B25%
7.20
7.20
7.20
7.20
7.20
135.46
135.46
135.46
135.46
135.46
136.26
136.26
136.26
136.26
136.26
136.26
136.26
136.26
136.26
136.26
136.62
136.62
136.62
136.62
136.62
0.003377
0.003374
0.003377
0.003377
0.003374
2.65
2.65
2.65
2.65
2.65
2.84
2.85
2.84
2.84
2.85
4.36
4.36
4.36
4.36
4.36
1.00
1.00
1.00
1.00
1.00
Byr Brook
Byr Brook
Byr Brook
3
3
3
184.716
184.716
184.716
Q100+CCA
Q100+CCA
Q100+CCA
St. Yd. C2 B25%
St. Yd. C3 B25%
St.Yd. B AC 25%
7.20
7.20
7.20
135.46
135.46
135.46
136.26
136.26
136.26
136.26
136.26
136.26
136.62
136.62
136.62
0.003377
0.003377
0.003374
2.65
2.65
2.65
2.84
2.84
2.85
4.36
4.36
4.36
1.00
1.00
1.00
Byr Brook
3
184.716
Q100+CCA
St.Yd. B AC 75%
7.20
135.46
136.26
136.26
136.62
0.003374
2.65
2.85
4.36
1.00
FRA262 – FCA
APPENDIX V:
1D MODELLING OUTPUTS - PROPOSED
FRA262 – FCA
206.209
232.359
239.269
252.265*
265.261*
278.258*
200
291.254*
184.87
304.25*
ok
165.156
ro
317.246*
B
Un
r
155.422*
330.242
na
By
me
145.689*
d
343.238* 3
Tr
ib
131.089*
356.234*
.
1
By
r B
r oo
k
2
367.94
121.355
Junc.1
477.04
486.70
500
184.716
Plan: St.Yd. Prop. Up/Downstream XS1
Byr Brook 3
10/11/2014
Byr Brook 1
Unnamed Trib. 2
144
Legend
WS Q1000
WS Q100+CCA
WS Q100
WS Q1
142
Ground
Elevation (m)
140
138
136
134
0
50
100
150
200
250
300
350
Plan: St.Yd. Prop. Up/Downstream XS1
10/11/2014
Legend
WS Q1
WS Q100
WS Q100+CCA
WS Q1000
Ground
Bank Sta
Ground
200
184.87
165.156
206.209
160.289*
155.422*
150.556
135.956
334.574*
351.902*
367.94 126.222*
477.04
486.70
317.246*
299.918
282.59*
252.265*
265.261*
239.269
232.359
184.716
HEC-RAS Plan: St.Yd. Pr. XS 1
River
Reach
River Sta
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
200
200
200
Unnamed Trib.
2
Unnamed Trib.
2
Unnamed Trib.
Unnamed Trib.
Profile
Q Total
Min Ch El
W.S. Elev
Crit W.S.
E.G. Elev
E.G. Slope
Vel Chnl
Flow Area
Top Width
(m3/s)
(m)
(m)
(m)
(m)
(m/m)
(m/s)
(m2)
(m)
Froude # Chl
Q1
Q100
Q100+CCA
0.30
1.50
1.80
141.96
141.96
141.96
142.24
142.63
142.69
142.24
142.63
142.69
142.35
142.86
142.95
0.004607
0.003197
0.003123
1.46
2.35
2.49
0.30
1.61
1.94
2.05
4.76
5.23
0.98
0.96
0.97
200
Q1000
2.70
141.96
142.87
142.87
143.17
0.002920
2.80
2.92
6.03
0.97
184.87
Q1
0.30
141.43
141.64
141.64
141.71
0.005774
1.13
0.27
2.15
1.00
2
2
184.87
184.87
Q100
Q100+CCA
1.50
1.80
141.43
141.43
141.89
141.93
141.89
141.93
142.06
142.13
0.003988
0.003790
1.88
1.99
0.95
1.12
3.45
3.70
0.99
0.99
Unnamed Trib.
2
184.87
Q1000
2.70
141.43
142.06
142.06
142.31
0.003413
2.25
1.63
4.46
0.98
Unnamed Trib.
Unnamed Trib.
2
2
182.862
182.862
Q1
Q100
0.30
1.50
140.94
140.94
141.37
141.76
141.37
141.76
141.48
141.98
0.007531
0.005772
1.47
2.06
0.20
0.76
0.94
2.30
1.01
0.99
Unnamed Trib.
2
182.862
Q100+CCA
1.80
140.94
141.82
141.82
142.06
0.005536
2.15
0.91
2.79
0.98
Unnamed Trib.
2
182.862
Q1000
2.70
140.94
141.98
141.98
142.26
0.005000
2.36
1.47
4.06
0.95
Unnamed Trib.
2
180.942
Q1
0.30
140.82
141.05
141.05
141.11
0.006101
1.07
0.28
2.45
1.01
Unnamed Trib.
Unnamed Trib.
2
2
180.942
180.942
Q100
Q100+CCA
1.50
1.80
140.82
140.82
141.54
141.70
141.57
141.73
0.000394
0.000248
0.78
0.73
2.09
2.80
4.35
4.72
0.33
0.28
Unnamed Trib.
2
180.942
Q1000
2.70
140.82
141.88
141.92
0.000262
0.87
3.67
5.15
0.29
Unnamed Trib.
2
176.548
Q1
0.30
140.40
140.72
140.81
0.006120
1.36
0.23
1.46
1.01
Unnamed Trib.
Unnamed Trib.
2
2
176.548
176.548
Q100
Q100+CCA
1.50
1.80
140.40
140.40
141.51
141.67
141.57
141.72
0.000457
0.000386
1.13
1.14
2.88
3.73
5.21
5.92
0.36
0.34
Unnamed Trib.
2
176.548
Q1000
2.70
140.40
141.82
141.91
0.000539
1.46
4.69
6.64
0.41
Unnamed Trib.
Unnamed Trib.
2
2
165.156
165.156
Q1
Q100
0.30
1.50
140.07
140.07
140.53
141.13
140.53
141.13
140.69
141.52
0.006676
0.004464
1.78
2.91
0.20
0.96
0.81
1.74
0.99
0.96
Unnamed Trib.
2
165.156
Q100+CCA
1.80
140.07
141.25
141.25
141.67
0.004113
3.03
1.19
1.94
0.95
Unnamed Trib.
2
165.156
Q1000
2.70
140.07
141.64
141.64
141.88
0.001973
2.59
4.69
12.02
0.69
Unnamed Trib.
2
160.289*
Q1
0.30
139.91
140.16
140.16
140.24
0.005869
1.24
0.24
1.60
1.01
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
160.289*
160.289*
160.289*
Q100
Q100+CCA
Q1000
1.50
1.80
2.70
139.91
139.91
139.91
140.44
140.49
140.59
140.44
140.49
140.59
140.59
140.65
140.79
0.004757
0.004647
0.004406
1.71
1.78
1.97
0.87
1.01
1.37
2.98
3.20
3.62
1.01
1.01
1.02
Unnamed Trib.
2
155.422*
Q1
0.30
139.76
139.96
139.96
140.03
0.005854
1.17
0.26
1.85
1.01
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
155.422*
155.422*
155.422*
Q100
Q100+CCA
Q1000
1.50
1.80
2.70
139.76
139.76
139.76
140.21
140.25
140.46
140.21
140.25
140.35
140.40
140.56
0.004694
0.004587
0.002054
1.65
1.71
1.41
0.91
1.05
1.92
3.32
3.56
4.78
1.01
1.01
0.71
Unnamed Trib.
2
150.556
Q1
0.30
139.60
139.77
139.77
139.84
0.005849
1.13
0.27
2.07
1.00
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
150.556
150.556
150.556
Q100
Q100+CCA
Q1000
1.50
1.80
2.70
139.60
139.60
139.60
140.01
140.05
140.51
140.01
140.05
140.14
140.19
140.54
0.004734
0.004622
0.000444
1.62
1.68
0.78
0.93
1.07
3.46
3.53
3.78
6.62
1.01
1.01
0.35
Unnamed Trib.
2
145.689*
Q1
139.60
139.60
1.95
1.01
Unnamed Trib.
2
145.689*
Q100
1.50
139.42
139.92
140.00
0.002467
1.31
1.15
3.66
0.74
Unnamed Trib.
Unnamed Trib.
2
2
145.689*
145.689*
Q100+CCA
Q1000
1.80
2.70
139.42
139.42
140.10
140.51
140.14
140.53
0.000913
0.000231
0.95
0.63
1.90
4.29
4.63
6.88
0.47
0.25
Unnamed Trib.
Unnamed Trib.
2
2
140.822*
140.822*
Q1
Q100
0.30
1.50
139.25
139.25
139.43
139.95
139.50
139.98
0.005793
0.000618
1.17
0.80
0.26
1.87
1.86
4.34
1.00
0.39
Unnamed Trib.
Unnamed Trib.
2
2
140.822*
140.822*
Q100+CCA
Q1000
1.80
2.70
139.25
139.25
140.11
140.52
140.13
140.53
0.000355
0.000136
0.68
0.53
2.64
5.11
5.11
7.05
0.30
0.20
Unnamed Trib.
2
135.956
Q1
0.30
139.07
139.25
139.32
0.005824
1.19
0.25
1.78
1.00
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
135.956
135.956
135.956
Q100
Q100+CCA
Q1000
1.50
1.80
2.70
139.07
139.07
139.07
139.96
140.12
140.52
139.97
140.13
140.53
0.000252
0.000174
0.000087
0.58
0.53
0.46
2.57
3.38
5.93
4.79
5.47
7.19
0.25
0.22
0.16
Unnamed Trib.
2
131.089*
Q1
0.30
138.89
139.16
139.19
0.012915
0.77
0.39
2.19
0.59
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
131.089*
131.089*
131.089*
Q100
Q100+CCA
Q1000
1.50
1.80
2.70
138.89
138.89
138.89
139.96
140.12
140.52
139.97
140.13
140.53
0.000647
0.000479
0.000252
0.38
0.36
0.33
3.91
5.01
8.29
6.58
7.44
8.37
0.16
0.14
0.10
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
126.222*
126.222*
126.222*
Q1
Q100
Q100+CCA
0.30
1.50
1.80
138.71
138.71
138.71
139.15
139.96
140.12
139.16
139.97
140.12
0.002791
0.000415
0.000366
0.28
0.24
0.24
1.06
6.32
7.43
4.33
7.06
7.06
0.18
0.08
0.08
Unnamed Trib.
2
126.222*
Q1000
2.70
138.71
140.52
140.52
0.000316
0.26
10.27
7.06
0.07
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
Unnamed Trib.
2
2
2
2
121.355
121.355
121.355
121.355
Q1
Q100
Q100+CCA
Q1000
0.30
1.50
1.80
2.70
138.53
138.53
138.53
138.53
139.16
139.96
140.12
140.52
139.16
139.97
140.12
140.52
0.000006
0.000011
0.000012
0.000014
0.09
0.19
0.20
0.24
3.31
7.95
8.85
11.16
5.75
5.75
5.75
5.75
0.04
0.05
0.05
0.06
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
500
500
500
500
Q1
Q100
Q100+CCA
Q1000
1.10
4.50
5.40
8.00
141.20
141.20
141.20
141.20
141.76
142.93
143.02
143.39
141.80
142.96
143.06
143.44
0.000792
0.000181
0.000206
0.000203
0.85
0.75
0.84
0.98
1.29
6.04
6.56
9.04
2.87
5.17
6.03
6.80
0.41
0.21
0.23
0.24
Byr Brook
Byr Brook
Byr Brook
1
1
1
486.70
486.70
486.70
Q1
Q100
Q100+CCA
1.10
4.50
5.40
141.09
141.09
141.09
141.78
142.93
143.03
141.79
142.95
143.05
0.000145
0.000087
0.000107
0.45
0.57
0.65
2.44
7.84
8.33
4.14
5.09
5.16
0.19
0.15
0.16
Byr Brook
1
486.70
Q1000
8.00
141.09
143.40
143.44
0.000118
0.78
10.65
6.60
0.18
Byr Brook
Byr Brook
Byr Brook
Byr Brook
1
1
1
1
477.04
477.04
477.04
477.04
Q1
Q100
Q100+CCA
Q1000
1.10
4.50
5.40
8.00
140.69
140.69
140.69
140.69
141.47
142.73
142.74
142.97
141.76
142.93
143.02
143.39
0.011753
0.003101
0.004383
0.005419
2.39
1.99
2.37
2.92
0.46
2.45
2.49
3.55
0.79
4.44
4.44
4.53
1.00
0.53
0.64
0.73
Byr Brook
1
473.49
Q1
1.10
140.66
141.16
141.16
141.41
0.008747
2.19
0.50
1.03
1.00
Byr Brook
Byr Brook
Byr Brook
1
1
1
473.49
473.49
473.49
Q100
Q100+CCA
Q1000
4.50
5.40
8.00
140.66
140.66
140.66
142.72
142.71
142.50
141.95
142.10
142.50
142.92
143.00
143.32
0.003040
0.004409
0.014673
1.99
2.39
4.02
2.48
2.46
2.00
3.97
3.89
1.43
0.46
0.56
1.00
Byr Brook
1
472.49
Byr Brook
Byr Brook
1
1
367.94
367.94
138.56
138.56
139.10
139.84
139.15
139.96
0.001245
0.001127
1.03
1.48
1.07
3.04
2.37
2.91
0.49
0.46
0.30
139.42
140.72
139.43
139.25
141.47
142.21
142.35
142.78
139.67
0.005860
1.15
0.26
Culvert
Q1
Q100
1.10
4.50
HEC-RAS Plan: St.Yd. Pr. XS 1 (Continued)
River
Reach
River Sta
Profile
Q Total
Min Ch El
W.S. Elev
Crit W.S.
E.G. Elev
E.G. Slope
Vel Chnl
Flow Area
Top Width
(m3/s)
(m)
(m)
(m)
(m)
(m/m)
(m/s)
(m2)
(m)
Froude # Chl
Byr Brook
Byr Brook
1
1
367.94
367.94
Q100+CCA
Q1000
5.40
8.00
138.56
138.56
139.99
140.36
140.11
140.51
0.001140
0.001157
1.56
1.73
3.46
4.63
3.02
3.29
0.46
0.46
Byr Brook
Byr Brook
3
3
364.253
364.253
Q1
Q100
1.40
6.00
138.56
138.56
138.97
139.52
Byr Brook
3
364.253
Q100+CCA
7.20
138.56
139.64
138.97
139.52
139.14
139.92
0.005395
0.005241
1.83
2.81
0.77
2.13
2.28
2.68
1.01
1.01
139.64
140.08
0.005196
2.95
2.44
2.76
Byr Brook
3
364.253
Q1000
10.70
138.56
139.92
1.00
139.92
140.47
0.005273
3.28
3.26
2.97
1.00
Byr Brook
3
360.566
Q1
1.40
138.37
138.87
Byr Brook
3
360.566
Q100
6.00
138.37
139.29
139.29
138.96
0.002637
1.39
1.01
2.73
0.73
139.65
0.004703
2.67
2.25
3.15
1.01
Byr Brook
Byr Brook
3
3
360.566
360.566
Q100+CCA
Q1000
7.20
10.70
138.37
138.37
139.39
139.64
139.39
139.64
139.79
140.14
0.004674
0.004635
2.80
3.12
2.57
3.43
3.25
3.50
1.01
1.01
Byr Brook
Byr Brook
Byr Brook
3
3
3
356.234*
356.234*
356.234*
Q1
Q100
Q100+CCA
1.40
6.00
7.20
138.28
138.28
138.28
138.80
139.26
139.35
138.80
139.26
139.35
138.94
139.59
139.72
0.005118
0.004336
0.004371
1.67
2.54
2.69
0.84
2.36
2.67
3.06
3.59
3.69
1.02
1.00
1.01
Byr Brook
3
356.234*
Q1000
10.70
Byr Brook
Byr Brook
3
3
351.902*
351.902*
Q1
Q100
1.40
6.00
138.28
139.58
139.58
140.04
0.004281
3.00
3.57
3.96
1.01
138.19
138.19
138.75
139.23
138.75
139.23
138.91
139.53
0.004997
0.004174
1.76
2.46
0.80
2.44
2.58
4.00
1.01
1.00
Byr Brook
3
351.902*
Q100+CCA
Byr Brook
3
351.902*
Q1000
Byr Brook
3
347.57*
Byr Brook
3
347.57*
Byr Brook
Byr Brook
3
3
347.57*
347.57*
Q100+CCA
Q1000
Byr Brook
Byr Brook
3
3
343.238*
343.238*
Q1
Q100
1.40
6.00
138.02
138.02
138.55
139.08
138.55
139.08
138.72
139.39
0.004959
0.004173
1.83
2.47
0.77
2.43
2.28
3.98
1.01
1.01
Byr Brook
3
343.238*
Q100+CCA
7.20
138.02
139.18
139.18
139.51
0.004078
2.56
2.81
4.27
1.01
Byr Brook
3
343.238*
Q1000
10.70
138.02
139.40
139.40
139.79
0.003868
2.78
3.86
4.99
1.01
Byr Brook
3
338.906*
Q1
1.40
137.93
138.44
138.44
138.61
0.004924
1.83
0.76
2.26
Byr Brook
3
338.906*
Q100
6.00
137.93
138.98
138.98
139.29
0.004169
2.49
2.41
3.87
1.01
Byr Brook
3
338.906*
Q100+CCA
7.20
137.93
139.07
139.07
139.41
0.004078
2.59
2.78
4.15
1.01
Byr Brook
3
338.906*
Q1000
10.70
137.93
139.30
139.30
139.70
0.003887
2.81
3.81
4.84
1.01
Byr Brook
3
334.574*
Q1
1.40
137.84
138.33
138.33
138.50
0.004906
1.83
0.76
2.27
1.01
Byr Brook
Byr Brook
3
3
334.574*
334.574*
Q100
Q100+CCA
6.00
7.20
137.84
137.84
138.86
138.96
138.86
138.96
139.18
139.30
0.004156
0.004064
2.50
2.60
2.40
2.77
3.82
4.10
1.01
1.01
Byr Brook
3
334.574*
Q1000
10.70
137.84
139.19
139.19
139.59
0.003880
2.82
3.79
4.76
1.01
Byr Brook
3
330.242
Q1
1.40
137.75
138.21
138.21
138.38
0.004866
1.82
0.77
2.31
1.01
Byr Brook
Byr Brook
3
3
330.242
330.242
Q100
Q100+CCA
6.00
7.20
137.75
137.75
138.75
138.85
138.75
138.85
139.06
139.18
0.004106
0.003956
2.50
2.58
2.40
2.79
3.82
4.10
1.01
1.00
Byr Brook
3
330.242
Q1000
10.70
137.75
139.08
139.08
139.48
0.003793
2.81
3.81
4.75
1.00
Byr Brook
3
325.91*
Q1
1.40
137.68
138.15
138.15
138.32
0.004859
1.82
0.77
2.30
1.00
Byr Brook
3
325.91*
Q100
6.00
137.68
138.68
138.68
139.00
0.004050
2.49
2.41
3.80
1.00
Byr Brook
Byr Brook
3
3
325.91*
325.91*
Q100+CCA
Q1000
7.20
10.70
137.68
137.68
138.78
139.12
138.78
139.01
139.12
139.43
0.004032
0.002711
2.60
2.48
2.77
4.32
4.05
5.01
1.01
0.85
Byr Brook
Byr Brook
3
3
321.578*
321.578*
Q1
Q100
1.40
6.00
137.61
137.61
138.08
138.61
138.08
138.61
138.25
138.94
0.004852
0.004129
1.82
2.51
0.77
2.39
2.29
3.76
1.00
1.01
Byr Brook
3
321.578*
Q100+CCA
7.20
137.61
138.71
138.71
Byr Brook
3
321.578*
Q1000
10.70
137.61
139.15
Byr Brook
3
317.246*
Q1
1.40
137.54
138.01
138.01
138.18
0.004890
1.83
0.76
2.27
1.01
Byr Brook
Byr Brook
3
3
317.246*
317.246*
Q100
Q100+CCA
6.00
7.20
137.54
137.54
138.55
138.67
138.55
138.64
138.87
138.99
0.004090
0.003633
2.51
2.51
2.39
2.87
3.74
4.07
1.00
0.95
Byr Brook
3
317.246*
Q1000
10.70
137.54
139.17
139.38
0.001620
2.05
5.22
5.41
0.67
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
312.914*
312.914*
312.914*
312.914*
Q1
Q100
Q100+CCA
Q1000
1.40
6.00
7.20
10.70
137.47
137.47
137.47
137.47
137.94
138.50
138.72
139.18
137.94
138.48
138.11
138.81
138.96
139.37
0.004913
0.003763
0.002444
0.001316
1.84
2.43
2.17
1.90
0.76
2.47
3.32
5.64
2.25
3.77
4.33
5.58
1.01
0.96
0.79
0.60
Byr Brook
Byr Brook
3
3
308.582*
308.582*
Q1
Q100
137.87
Byr Brook
Byr Brook
3
3
308.582*
308.582*
Q100+CCA
Q1000
Byr Brook
3
304.25*
Q1
Byr Brook
Byr Brook
Byr Brook
3
3
3
304.25*
304.25*
304.25*
Q100
Q100+CCA
Q1000
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
299.918
299.918
299.918
299.918
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
Byr Brook
Byr Brook
Byr Brook
7.20
138.19
139.31
139.31
139.65
0.004120
2.59
2.78
4.11
1.00
10.70
138.19
139.52
139.52
139.95
0.004071
2.90
3.69
4.39
1.01
Q1
1.40
138.10
138.66
138.66
138.82
0.004995
1.81
0.77
2.37
1.01
Q100
6.00
138.10
139.18
139.18
139.47
0.004144
2.42
2.47
4.19
1.01
7.20
10.70
138.10
138.10
139.26
139.47
139.26
139.47
139.59
139.87
0.004105
0.003945
2.53
2.82
2.85
3.80
4.48
4.79
1.01
1.01
1.40
6.00
137.40
137.40
137.87
138.55
7.20
10.70
137.40
137.40
138.74
139.20
1.40
137.33
137.80
6.00
7.20
10.70
137.33
137.33
137.33
138.57
138.76
139.20
Q1
Q100
Q100+CCA
Q1000
1.40
6.00
7.20
10.70
137.26
137.26
137.26
137.26
137.73
138.59
138.77
139.21
295.586*
295.586*
295.586*
295.586*
Q1
Q100
Q100+CCA
Q1000
1.40
6.00
7.20
10.70
137.19
137.19
137.19
137.19
3
3
3
291.254*
291.254*
291.254*
Q1
Q100
Q100+CCA
1.40
6.00
7.20
Byr Brook
3
291.254*
Q1000
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
286.922*
286.922*
286.922*
286.922*
Q1
Q100
Q100+CCA
Q1000
Byr Brook
3
282.59*
Q1
137.80
1.01
139.06
0.003988
2.60
2.77
4.03
1.00
139.40
0.002049
2.23
4.79
5.23
0.75
138.04
138.77
0.004917
0.002455
1.84
2.08
0.76
2.89
2.24
4.03
1.01
0.78
138.93
139.35
0.001818
0.001089
1.94
1.77
3.71
6.05
4.53
5.73
0.69
0.55
137.97
0.004926
1.84
0.76
2.23
1.01
138.75
138.91
139.34
0.001795
0.001413
0.000916
1.85
1.77
1.66
3.24
4.07
6.44
4.23
4.71
5.88
0.67
0.61
0.51
137.73
137.91
138.73
138.90
139.34
0.004935
0.001371
0.001126
0.000778
1.85
1.67
1.63
1.56
0.76
3.58
4.42
6.84
2.21
4.41
4.87
6.01
1.01
0.59
0.55
0.47
137.66
138.60
138.78
139.22
137.66
137.84
138.72
138.89
139.33
0.004940
0.001062
0.000901
0.000656
1.85
1.52
1.50
1.47
0.76
3.94
4.81
7.29
2.21
4.60
5.06
6.19
1.01
0.52
0.49
0.43
137.12
137.12
137.12
137.59
138.61
138.78
137.59
137.77
138.71
138.88
0.004945
0.000841
0.000733
1.85
1.40
1.39
0.76
4.30
5.19
2.20
4.78
5.24
1.01
0.47
0.44
10.70
137.12
139.23
139.32
0.000559
1.38
7.74
6.36
0.40
1.40
6.00
7.20
10.70
137.05
137.05
137.05
137.05
137.55
138.61
138.79
139.23
137.70
138.70
138.88
139.32
0.004103
0.000678
0.000604
0.000479
1.73
1.29
1.29
1.30
0.81
4.66
5.58
8.20
2.26
4.96
5.41
6.52
0.92
0.42
0.41
0.37
1.40
136.98
137.58
137.67
0.002032
1.34
1.05
2.51
0.66
137.52
HEC-RAS Plan: St.Yd. Pr. XS 1 (Continued)
River
Reach
River Sta
Profile
Q Total
Min Ch El
W.S. Elev
Crit W.S.
E.G. Elev
E.G. Slope
Vel Chnl
Flow Area
Top Width
(m3/s)
(m)
(m)
(m)
(m)
(m/m)
(m/s)
(m2)
(m)
Froude # Chl
Byr Brook
Byr Brook
Byr Brook
3
3
3
282.59*
282.59*
282.59*
Q100
Q100+CCA
Q1000
6.00
7.20
10.70
136.98
136.98
136.98
138.62
138.80
139.23
138.69
138.87
139.31
0.000553
0.000503
0.000414
1.19
1.20
1.24
5.03
5.98
8.66
5.13
5.58
6.68
0.38
0.37
0.35
Byr Brook
3
278.258*
Byr Brook
3
278.258*
Q1
1.40
136.91
137.59
137.65
0.001231
1.11
1.26
2.71
0.52
Q100
6.00
136.91
138.62
138.69
0.000457
1.11
5.40
5.30
Byr Brook
Byr Brook
3
3
278.258*
278.258*
Q100+CCA
Q1000
0.35
7.20
10.70
136.91
136.91
138.80
139.24
138.87
139.31
0.000423
0.000359
1.13
1.17
6.38
9.13
5.74
6.84
0.34
0.32
Byr Brook
3
273.926*
Q1
1.40
136.84
137.60
137.64
0.000804
0.95
1.47
2.89
0.43
Byr Brook
Byr Brook
3
3
273.926*
273.926*
Q100
Q100+CCA
6.00
7.20
136.84
136.84
138.63
138.80
138.68
138.86
0.000381
0.000358
1.04
1.06
5.78
6.78
5.47
5.91
0.32
0.32
Byr Brook
3
273.926*
Q1000
10.70
136.84
139.24
139.30
0.000313
1.11
9.61
7.00
0.30
Byr Brook
Byr Brook
3
3
269.594
269.594
Q1
Q100
1.40
6.00
136.77
136.77
137.60
138.63
137.64
138.68
0.000552
0.000320
0.83
0.97
1.69
6.17
3.07
5.63
0.36
0.30
Byr Brook
Byr Brook
3
3
269.594
269.594
Q100+CCA
Q1000
7.20
10.70
136.77
136.77
138.81
139.24
138.86
139.30
0.000305
0.000275
1.00
1.06
7.20
10.09
6.07
7.15
0.29
0.29
Byr Brook
3
265.261*
Q1
1.40
136.70
137.60
137.63
0.000510
0.81
1.73
2.99
0.34
Byr Brook
3
265.261*
Q100
6.00
136.70
138.63
138.68
0.000335
0.99
6.05
5.42
0.30
Byr Brook
Byr Brook
3
3
265.261*
265.261*
Q100+CCA
Q1000
7.20
10.70
136.70
136.70
138.80
139.24
138.86
139.30
0.000322
0.000294
1.02
1.09
7.04
9.81
5.83
6.87
0.30
0.29
Byr Brook
3
260.929*
Q1
1.40
136.63
137.60
137.63
0.000498
0.81
1.74
2.87
0.33
Byr Brook
Byr Brook
3
3
260.929*
260.929*
Q100
Q100+CCA
6.00
7.20
136.63
136.63
138.62
138.80
138.68
138.85
0.000364
0.000353
1.03
1.06
5.85
6.78
5.16
5.55
0.31
0.31
Byr Brook
3
260.929*
Q1000
10.70
136.63
139.23
139.30
0.000327
1.14
9.41
6.52
0.30
Byr Brook
3
256.597*
Q1
1.40
136.56
137.59
137.63
0.000522
0.82
1.70
2.72
0.33
Byr Brook
3
256.597*
Q100
6.00
136.56
138.61
138.67
0.000417
1.08
5.55
4.83
0.32
Byr Brook
Byr Brook
3
3
256.597*
256.597*
Q100+CCA
Q1000
7.20
10.70
136.56
136.56
138.79
139.22
138.85
139.30
0.000407
0.000382
1.12
1.21
6.42
8.87
5.19
6.09
0.32
0.32
Byr Brook
3
252.265*
Q1
Byr Brook
3
252.265*
Q100
Byr Brook
Byr Brook
3
3
252.265*
252.265*
Q100+CCA
Q1000
Byr Brook
Byr Brook
3
3
247.933*
247.933*
Q1
Q100
Byr Brook
Byr Brook
3
3
247.933*
247.933*
Q100+CCA
Q1000
Byr Brook
Byr Brook
3
3
243.601*
243.601*
Q1
Q100
1.40
6.00
136.35
136.35
137.55
138.52
137.62
138.66
0.001399
0.001290
1.17
1.62
1.20
3.70
1.86
3.26
0.47
0.49
Byr Brook
3
243.601*
Q100+CCA
7.20
136.35
138.69
138.84
0.001218
1.69
4.29
3.97
0.48
Byr Brook
3
243.601*
Q1000
10.70
136.35
139.10
139.28
0.001022
1.87
6.53
6.83
0.46
Byr Brook
3
239.269
Q1
1.40
136.28
137.32
137.32
137.58
0.009240
2.28
0.61
1.18
1.01
Byr Brook
Byr Brook
3
3
239.269
239.269
Q100
Q100+CCA
6.00
7.20
136.28
136.28
138.15
138.28
138.15
138.28
138.61
138.79
0.007459
0.007239
3.03
3.15
1.98
2.29
2.12
2.36
1.00
1.00
Byr Brook
3
239.269
Q1000
10.70
136.28
138.63
138.63
139.23
0.006021
3.44
3.40
4.29
0.95
Byr Brook
3
232.359
Q1
1.40
136.35
136.67
136.67
136.80
0.004896
1.63
0.86
3.19
1.01
Byr Brook
3
232.359
Q100
6.00
136.35
137.12
137.12
137.40
0.004079
2.37
2.53
4.47
1.01
Byr Brook
Byr Brook
3
3
232.359
232.359
Q100+CCA
Q1000
7.20
10.70
136.35
136.35
137.20
137.40
137.20
137.40
137.51
137.78
0.003991
0.003612
2.47
2.71
2.92
4.16
4.77
7.63
1.01
0.99
Byr Brook
Byr Brook
3
3
206.209
206.209
Q1
Q100
1.40
6.00
135.96
135.96
136.30
136.71
136.30
136.71
136.43
137.01
0.005189
0.003939
1.58
2.42
0.89
2.56
3.54
5.69
1.01
1.00
Byr Brook
Byr Brook
3
3
206.209
206.209
Q100+CCA
Q1000
7.20
10.70
135.96
135.96
136.79
137.02
136.79
137.02
137.12
137.40
0.003640
0.002991
2.54
2.78
3.11
5.35
7.25
11.16
0.98
0.93
Byr Brook
Byr Brook
Byr Brook
Byr Brook
3
3
3
3
184.716
184.716
184.716
184.716
Q1
Q100
Q100+CCA
Q1000
1.40
6.00
7.20
10.70
135.46
135.46
135.46
135.46
135.79
136.18
136.26
136.48
135.79
136.18
136.26
136.48
135.91
136.50
136.62
136.94
0.004865
0.003500
0.003374
0.003070
1.54
2.49
2.65
3.02
0.91
2.50
2.85
3.82
3.83
4.27
4.36
4.74
1.00
1.00
1.00
1.00
1.40
136.49
137.59
137.63
0.000602
0.87
1.61
2.51
0.35
6.00
136.49
138.60
138.67
0.000517
1.17
5.12
4.42
0.35
7.20
10.70
136.49
136.49
138.77
139.20
138.85
139.29
0.000507
0.000470
1.22
1.32
5.91
8.15
4.75
5.94
0.35
0.34
1.40
6.00
136.42
136.42
137.58
138.58
137.62
138.67
0.000802
0.000725
0.96
1.32
1.45
4.53
2.23
3.91
0.38
0.39
7.20
10.70
136.42
136.42
138.75
139.17
138.84
139.29
0.000714
0.000608
1.38
1.51
5.23
7.44
4.20
6.72
0.39
0.38
FRA262 – FCA
APPENDIX W: NOTES OF LIMITATION
The data essentially comprised a study of available documented information from various sources
together with discussions with relevant authorities and other interested parties. There may also be
circumstances at the site that are not documented.
The information reviewed is not exhaustive and has been accepted in good faith as providing
representative and true data pertaining to site conditions. If additional information becomes
available which might impact our l conclusions, we request the opportunity to review the
information, reassess the potential concerns and modify our opinion if warranted.
It should be noted that any risks identified in this report are perceived risks based on the available
information.
This report was prepared by Betts Associates Ltd for the sole and exclusive use of the titled client in
response to particular instructions. Any other parties using the information contained in this report
do so at their own risk and any duty of care to those parties is excluded.
This document has been prepared for the titled project only and should any third party wish to use
or rely upon the contents of the report, written approval from Betts Associates Ltd must be sought.
Betts Associates Ltd accepts no responsibility or liability for the consequences of this document
being used for the purpose other than that for which it was commissioned and for this document to
any other party other than the person by whom it was commissioned.
FRA262 – FCA

station yard corwen road, coed-talon flood consequence assessment

Transcription

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