Swansea Valley Business Park, Ystalafera · 2020-05-26 · The geology at the site is described as...
Transcript of Swansea Valley Business Park, Ystalafera · 2020-05-26 · The geology at the site is described as...
Swansea Valley Business Park, Ystalafera
Flood Consequences Assessment
April 2020
Tulip Engineering Consultancy Limited 34 Culfor Road, Loughor, Swansea SA4 6TY
www.tulipengineering.co.uk
© 2020 Google
Client Name: CB3 Consult Ltd.
Document Reference: FCA/01
Project Number: J009
Issue Date Author Comments
01 14.04.2020 Graeme Tulip BEng CEng MICE
First Issue
This report has been prepared for the sole and exclusive use of CB3 Consult Ltd from whom it was commissioned in response to their particular requirements and brief.
This report may not be relied upon by any other party.
The contracts (Rights of Third Parties) Act 1999 shall not apply to this report and the provisions of the said Act are expressly excluded from this report.
This report may not be used for any purpose other than that for which it was commissioned.
This report may not be reproduced and/or made public by any means without the prior written permission of Tulip Engineering Consultancy Ltd.
Information, views and conclusions presented in this report are based on information provided by others. That information has neither been checked nor verified by Tulip Engineering Consultancy Ltd. Tulip Engineering Consultancy Ltd accepts no liability for any inaccuracy resulting from inaccurate information provided by others.
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Contents
1. Introduction ................................................................................................................................. 2 1.1 Terms of Reference ........................................................................................................ 2
2. Site Description .......................................................................................................................... 3 2.1 Location ........................................................................................................................... 3 2.2 Watercourses .................................................................................................................. 4 2.3 Topography .................................................................................................................... 4 2.4 Soils, Geology & Hydrogeology ................................................................................... 5 2.5 History ............................................................................................................................. 5
3. Proposed Development ............................................................................................................. 6 3.1 Layout .............................................................................................................................. 6 3.2 Levels .............................................................................................................................. 6
4. Planning Policy and Flood Risk ................................................................................................. 7 4.1 Proposed Development and TAN 15 ............................................................................ 7 4.2 Justification Test ............................................................................................................ 7
5. Existing Flood Risk Review ....................................................................................................... 8 5.1 Historical Flooding ......................................................................................................... 8 5.2 Fluvial Flood Risk ........................................................................................................... 8 5.3 Surface Water Flood Risk .............................................................................................. 8 5.4 Reservoir Flood Risk ...................................................................................................... 8 5.5 Groundwater Flood Risk ................................................................................................ 8
6. Hydraulic Modelling ................................................................................................................... 9 6.1 Existing Hydraulic Model .............................................................................................. 9 6.2 Updated Hydraulic Modelling ....................................................................................... 9
7. Conclusions & Recommendations .......................................................................................... 11
Appendices A. LIDAR Plan, Topographical Survey Plan
B. Architectural Site Plan, 3D Image
C. Flood Maps
D. Hydraulic Modelling Technical Note
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1. Introduction
1.1 Terms of Reference
Tulip Engineering Consultancy was commissioned by CB3 Consult Ltd to prepare this Flood Consequences Assessment (FCA) to support a planning application for the development of Industrial Units on brownfield land at Swansea Valley Business Park, Glan Yr Afon, Ystalyfera. Industrial development is classified as “less vulnerable” development in Technical Advice Note (TAN) 15 Development & Flood Risk (Welsh Assembly Government, 2004).
The proposed development site lies within Zone C2 of the Development Advice Map (DAM) published by Natural Resources Wales (NRW). Zone C2 is defined as areas at risk of flooding “without significant flood defence infrastructure” (Welsh Assembly Government, 2004).
The objective of this report is to undertake a study into the hydrological issues affecting the site, and establish whether and to what extent the consequences of flooding can be managed over the lifetime of the development, using the principles and tests set out in TAN 15.
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2. Site Description
2.1 Location
Swansea Valley Business Park is an established industrial site which lies between Ystalyfera to the north and Godrergraig to the south. The site is directly bounded to the east by the A4067 Glanyrafon Road, with the banks of the River Tawe situated parallel to the road and approximately 70m away in the south-easterly direction.
The National Grid Reference for the site is: SN 76505 08226.
A site location plan is shown in Figure 1.
Figure 1: Site Location Ordnance Survey Data © Crown Copyright and Database Right 2020
An aerial view of the site is shown in Figure 2.
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Figure 2: Aerial View showing Site Location © 2020 Google
2.2 Watercourses
The Afon Tawe is a designated main river which rises in the Brecon Beacons above Llyn y Fan at 590m above sea level and flows in a generally south-westerly direction to Swansea Bay. The river drains a total catchment of some 270km2. The Tawe flows approximately 70m to the east of the proposed development.
The Afon Twrch, also a designated main river and a main tributary of the Tawe, rises in the Black Mountains and flows in a generally southerly direction to Ystalyfera where it joins the Tawe approximately 0.7km north-east of the development site. The Afon Twrch catchment is approximately 50km2 at the confluence with the Tawe.
2.3 Topography
The development site sits in the relatively flat Tawe valley floor some 70m from the river. The width of the valley floor is some 0.8km at this point. The valley floor area widens markedly upstream (north) of the site, where the Twrch joins the Tawe and the two valleys merge.
A plan showing the site location, lidar ground levels, and all OS-mapped watercourses (main rivers and ordinary watercourses) in the vicinity is included in Appendix A.
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A topographical survey of the development area and adjacent industrial unit dated March 2016 is also included in Appendix A. This shows that the level of the rectangular development plateau is raised some 1m above the adjacent industrial land to the west.
The development site elevation ranges between approximately 58.0m AOD at the northern end to 59.0m AOD at the southern end. The large existing industrial unit and the industrial estate access road immediately to the west are at a lower level of approximately 56.8m AOD. The main road (A4067) to the east is at a similar level to the development site.
2.4 Soils, Geology & Hydrogeology
Site soils are described as loamy in texture and freely draining according to the Cranfield University Soilscapes Viewer.
The geology at the site is described as superficial alluvial deposits (clay, silt, sand and gravel) overlying mudstone, siltstone and sandstone bedrock, according to the BGS Geology of Britain Viewer.
The aquifer designation of the sedimentary bedrock is Secondary A (capable of supporting water supplies at a local rather than strategic scale). The site is not in a groundwater Source Protection Zone area.
2.5 History
The area in the vicinity of the site was historically the location of the Ystalafera Iron & Tin Plate Works. An overlay showing the site location in relation to the 1910 OS Map is shown in Figure 3.
Figure 3: Historical OS Map showing Site Location Ordnance Survey Data © Crown Copyright 2020
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3. Proposed Development
3.1 Layout
The proposed development consists of two industrial sheds housing seven business starter units, with associated access road and parking spaces.
The existing industrial estate access road is to be realigned to run some 7m closer to the existing adjacent industrial building, to increase the developable area of the plot.
Proposed architectural plans and elevations are included in Appendix B.
3.2 Levels
Proposed carpark and building floor levels are not yet finalised, although it is anticipated that proposed ground levels will be similar to existing levels, with small localised differences due to cut/fill redistribution to flatten out the bank at the northern site boundary.
The realigned access road profile will need to be set to ensure suitable access to both the proposed site and tie in to the adjacent large existing industrial unit.
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4. Planning Policy and Flood Risk
4.1 Proposed Development and TAN 15
The development proposal is for industrial units on brownfield land in an industrial area of Ystalafera. Industrial development is classified as ‘less vulnerable’ development in TAN 15.
The Development Advice Map (DAM) is a flood map published by NRW for land use planning purposes. It is used alongside Planning Policy Wales and Technical Advice Note (TAN) 15 to direct new development in respect to flood risk. Together, they form a precautionary framework to guide planning applications.
The map is based on Natural Resource Wales' extreme flood outlines (zone C) and the British Geological Survey drift data (zone B). Zone B data was originally published 2004 and updated in 2017. Zone C data is revised quarterly by ongoing hydraulic modelling and represents areas affected by flooding in events with up to a 1 in 1000 annual chance of occurring (0.1% Annual Event Probability), but no allowance for future climate change.
The Development Advice Map in the vicinity of the proposed development is included in Appendix C. The Map shows that the development site currently lies within the blue shaded zone C2 area, defined as “areas of the floodplain without significant flood defence infrastructure”.
TAN15 provides for less vulnerable development in zone C2, subject to application of the justification test, including acceptability of consequences.
4.2 Justification Test
TAN15 Section 6 states that development will be justified if it can be demonstrated that:
1. Its location in zone C is necessary to assist or be part of a local authority regeneration initiative or a local authority strategy required to sustain an existing settlement; or
2. Its location in zone C is necessary to contribute to key employment objectives supported by the local authority, and other key partners, to sustain an existing settlement or region; and
3. It concurs with the aims of Planning Policy Wales and meets the definition of previously developed land; and
4. The potential consequences of a flooding event for the particular type of development have been considered and found to be acceptable.
In this case this development is considered to meet the second and third criteria, whilst the fourth is supported by updated flood modelling undertaken specifically for this FCA, as described in Section 6 and Appendix D of this report.
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5. Existing Flood Risk Review
5.1 Historical Flooding
The site has not experienced any flooding in the past according to NRW’s map of historical flood outlines.
5.2 Fluvial Flood Risk
The NRW Zone 2 & 3 Map in Appendix C shows the lower part of the site in zone 3 (up to 1 in 100 annual chance of flooding) and the remaining higher part of the site in zone 2 (up to 1 in 1000 annual chance of flooding).
This map also indicates that the zone 3 area is classed as ‘area benefitting from flood defences’, although this area is not shown as green-coloured zone C1 (defended) on the DAM Map.
A additional ‘Flood Zone Plan’ is included in Appendix C, showing flood zones 2 & 3 overlaid on an map which also includes the site topographical survey, lidar ground elevation data and OS watercourses.
It is important to note that this is the fluvial flood risk as shown on the current (existing) flood maps which guide the planning process. The updated fluvial flood modelling described in Section 6 effectively supersedes this existing fluvial flood risk.
5.3 Surface Water Flood Risk
The surface water flood risk map included in Appendix C shows a high risk area along the existing access road to the industrial estate, with the remainder of the development plot in very low or low risk area.
The existing access road will be reprofiled and drained as part of this development proposal. Furthermore the development site itself will be subject to sustainable drainage design/SAB approval and as such it is considered unlikely that the proposed development will increase the risk of surface water flooding or the rate and volume of surface water runoff.
5.4 Reservoir Flood Risk
The development site is not at risk of flooding from reservoir failure according to NRW’s flood risk mapping.
5.5 Groundwater Flood Risk
The development site is not in an area prone to groundwater flooding according to available BGS mapping, which is supported by NPT’s Local Flood Risk Management Strategy which states that there are no specific areas of groundwater flooding recorded historically in the NPT area.
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6. Hydraulic Modelling
6.1 Existing Hydraulic Model
This section of the report will reassess the flood risk indicated by the DAM maps and establish whether the consequences of the risk of flooding may be considered acceptable.
The current DAM Map flood outline in the site locality is informed by the results of flood modelling undertaken in 2016 by JBA Consulting for the Ysgol Gyfun Ystalafera Flood Consequences Assessment. This model was in turn based largely on a 2013 Cwm Twrch 1D-2D model also developed by JBA Consulting on behalf of NRW.
The hydrology calculations from 2016 have now become outdated due to ongoing developments in hydrology methods, guidance and data availability. As part of this development FCA, updated hydrology and modelling has been commissioned.
6.2 Updated Hydraulic Modelling
The updated modelling undertaken by JBA Consulting for this FCA encompassed updated hydrology (input flow) calculations, more realistic application of input flows and 1D model updates. Model scenarios were run using the latest TUFLOW software and current climate change (30%) allowance.
A Technical Note from JBA Consulting summarising the updated modelling exercise, is included in Appendix D of this report.
Results from the updated modelling show that the proposed development floods in neither the 1 in 100 (1%) AEP with climate change allowance, nor the 1 in 1000 (0.1%) AEP. The 0.1% AEP flood map extent is shown in Figure 4.
Flooding is shown to emanate from the right bank of the Afon Twrch some 1km upstream of the site at Ysgol Gyfun Ystalafera. The overland flood flow-path is then southerly before ponding around Varteg Road, but does not reach beyond the roundabout towards the development site.
TAN15 guidelines require a flood-free development level for fluvial flood risk of 1% (1 in 100 annual chance) probability over the lifetime of the development. The updated modelling results displayed in Figure 4 show that the proposed development would be compliant with the flood-free development level criteria (A1.14) of TAN15. Consequently it is clear that no ground level alterations would be required in order to meet this criteria.
Emergency access/egress to/from the site needs to be considered in light of the TAN15 recommendations. The map in Figure 4 indicates that the immediate site access road and mini-roundabout would be flood free during the 0.1% AEP event. The main A4067 Glan Yr Afon road roundabout is shown to suffer flooding up to a depth of 0.6m on the eastern side, which is within the “maximum permissible floodwater depth over the defined route during extreme flooding” figure of 1.0m given in A1.15 of TAN15.
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Whilst access to the A4067 during the 0.1% APE event may be hampered, the availability of the B4599 would be unaffected and would allow for safe evacuation from the site or access for emergency vehicles if required.
The ‘no flooding elsewhere’ criterion of TAN15 is considered negligible in this assessment since it has been demonstrated that the site would not flood during either the 1%CC or 0.1% AEP events.
Figure 4: Updated Model: 0.1% AEP Flood Depths
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7. Conclusions & Recommendations
• This planning application is for industrial development (classed as less vulnerable in TAN15) on brownfield land at Swansea Valley Business Park.
• The requirement for this FCA is due to the proposed development site location in the flood plain (zone C2 of the current Welsh Government Development Advice Map).
• However, updated flood modelling undertaken specifically for this FCA for this development, has demonstrated that the proposed development site is outside the flood plain, that is, flood-free during both the 1%CC and 0.1% AEP events.
• The most up to date analysis of flood risk to the site is therefore shown to be less than that suggested by the current DAM Map, and the key TAN15 acceptability tests in relation to flood-free floor level, no flooding elsewhere and access/egress are all met by default.
• The proposed development is compliant with all key aspects of TAN15 and as such it is considered that this land is suitable for industrial development in relation to planning policy and flood risk.
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APPENDICES
A. LIDAR Plan, Topographical Survey Plan
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U
R
N
O
S
R
O
A
D
Gurnos
4
6
1
9
2
22
T
a
n
-
y
-
c
o
e
d
1
4
2
H
E
O
L
A
B
R
A
M
7
B
4
5
9
9
1
30
Pinetree Lodge
11
7
1
1
7
2
W
o
r
k
s
2
8
Y
r
-
H
e
n
-
B
o
n
t
1
5
9
2
67.8m
GP
Birkdale
4
1
79.6m
3
6
4
1
6
Wharf
67.1m
1
0
69.9m
9
4
4
Bungalow
5
1
3
3
1
5
a
El Ps
6
8
9
A
L
D
E
R
A
V
E
N
U
E
El Ps
6
6
90
Path (um)
Path (um)
Tank
LB
Path (um)
P
a
t
h
(
u
m
)
T
r
a
c
k
Tank
18
1
0
Shelter
The Beeches
B
r
y
n
b
a
c
h
1
0
1 to 4
3
5
D
a
n
-y-C
o
e
d
Varteg
House
Brook
Lodge
Playground
Y
C
e
d
r
w
y
d
d
L
L
Y
S
Y
N
Y
S
C
E
D
W
Y
N
8
1
4
3
G
O
R
O
F
1
6
Oak Villas
2
1
6
2
0
7
2
1
9
2
1
0
2
1
3
2
1
4
P
a
th
(
u
m
)
(disused)
P
a
t
h
Outfall
Mast
C
y
c
l
e
P
a
t
h
C
y
c
le
P
a
t
h
1
3
1
5
T
r
a
c
k
M
a
e
s
g
w
y
n
Lighting Tower
C
y
c
l
e
P
a
t
h
5
5
107
/ Parc Menter
Ynyscedwyn
Enterprise Park
126b
126a
Llys-Swynol
27
2
4
1
3
5
5
D
e
l
f
a
n
L
l
e
c
h
w
e
d
d
G
R
A
I
G
N
E
W
Y
D
D
1
h
1
g
Cwar
T
r
a
c
k
C
R
I
M
E
A
C
O
U
R
T
7
2
1
2
1
4
10
9
El Sub Sta
E
l
S
u
b
S
t
a
N
e
w
l
y
n
TA
W
E
P
A
R
K
3
5
3
3
4
10
2
Chy
76
5
2
67.8m
5
6
5
2
6
4
7
72.4m
73.7m
7
3
36
2
4
4
25
6
8
7
5
111
El Sub Sta
1
0
5
Club
G
la
n
n
a
n
t
H
o
Stand
1
3
6
1
6
2
Sluice
Pantteg
7
1
c
P
a
t
h
13
8
8
7
(disused)
P
a
t
h
(
u
m
)
6
8
7
1
0
8
3
1
W
A
D
E
A
V
E
N
U
E
1
2
0
8
8
1
3
4
4
65.6m
H
O
D
G
S
O
N
'
S
R
O
A
D
(disused)
(disused)
Briardale
6
9
T
r
a
c
k
1
b
P
a
t
h
(
u
m
)
T
r
a
c
k
1
f
Level
2
Pol
2
89.1m
28
25
1
Heulwen
130.4m
FB
V
I
N
E
R
O
W
9
167.6m
1
6
0
6
6
2
1
8
7
C
A
N
A
L
T
E
R
R
A
C
E
82.7m
7
D
A
R
R
E
N
R
O
A
D
P
a
t
h
(
u
m
)
5
3
10
1
3
6
Path (um
)
4
9
S
C
H
O
O
L
R
O
A
D
4
4
1
3
1
5
A
4
0
6
7
18
4
7
108.7m
1
1
5
4
1
4
Path (um
)
1
1
3
W
e
r
n
V
i
l
l
a
s
Brynderwyn
5
1
1
2
2
66.5m
3
8
H
a
l
l
5
(disused)
West
6
0
94.9m
Level
FB
52.7m
F
o
u
n
t
a
i
n
H
a
l
l
1
8
2
1
1
d
Level
1
5
(disused)
P
a
t
h
(
u
m
)
1
7
C
h
e
m
i
c
a
l
R
o
w
8
a
Weir
Level
T
ra
c
k
Mine
6
3
1
a
7
3
4
1
2
D
a
r
r
e
n
F
a
c
h
3
9
Mine
Pen-y-graig
H
a
l
l
1
2
(disused)
5
6
1
5
51.2m
2
9
T
r
a
c
k
52.2m
FBs
4
7
T
C
B
130.4m
B
u
n
g
a
l
o
w
Danygraig
T
r
a
c
k
1
7
1
0
Lower
G
R
A
I
G
Y
D
A
R
R
E
N
8
1
G
R
A
I
G
Y
M
E
R
C
H
E
D
Pavilion
P
E
N
Y
W
E
R
N
R
O
A
D
8
0
6
1
A
rn
o
ld
C
o
u
rt
65.9m
E
l
S
u
b
S
t
a
6
3
1
60
V
A
R
T
E
G
R
O
A
D
P
W
2
2
T
e
n
n
i
s
C
o
u
r
t
s
1
3
2
5
1
Bowling Green
24
59.8m
1
The Poplars
1
7
69
8
4
LB
1
2
0
4
6
1
2
2
6
2
4
7
4
P
H
7
T
H
E
G
A
R
D
E
N
S
2
9
4
Post
W
E
R
N
W
O
O
D
R
O
A
D
1
2
5
a
11
1
1
0
3
7
2
7
64
5
3
E
l
S
u
b
S
t
a
8
7
3
3
9
P
H
1
8
6
2
3
1
99.1m
9
2
2
2
2
2
58.7m
6
5
6
2
1
8
Car Park
3
7
2
4
Y
N
Y
S
Y
D
A
R
R
E
N
R
O
A
D
/
H
E
O
L
Y
N
Y
S
Y
D
A
R
R
E
N
1
4
3
4
T
ra
c
k
8
1
0
0
P
a
th
(u
m
)
4
1
7
1
5
39
1
1
4
8
8
1
7
C
y
s
t
a
n
o
g
Parc-y-Darren
7
2
P
a
t
h
(
u
m
)
8
1
S
u
n
n
y
v
ille
4
102.3m
59.7m
LAN
E
(disused)
53
104.2m
1
2
1
2
1
1
2
2
M
a
e
s
-
y
-
w
e
r
n
1
0
14
8
3
7
5
a
56
2
4
5
6
2
4
5
2
8
1
5
3
1
3
7
G
L
A
N
-
Y
R
-
Y
S
G
O
L
4
1
42
27
(disused)
El Sub Sta
60.9m
W
E
M
B
L
E
Y
R
O
A
D
4
2
8
1
5
2
4
1
3
3
0
19
165.5m
1
1
1
2
0
62.2m
1
2
8
Meml
2
0
2
3
3
2
PH
W
O
O
D
M
A
N
S
T
E
R
R
A
C
E
1
5
4
0
2
7
1
6
3
6
7
1
6
5
1
1
e
F
F
O
R
D
D
G
L
A
N
D
W
R
7
9
4
1
4
1
7
2
0
2
3
2
1
0
E
l
Mynydd Allt-y-grug
2
4
17
6
0
5
4
8
2
1
0
88.3m
T
r
a
c
k
El
7
1
2
1
2
0
4
(disused)
G
R
A
I
G
R
O
A
D
88.1m
6
Sub Sta
2
2
Tarren y G
igfran
2
1
78.7m
28
(disused)
1
9
8
1
0
4
1
0
8
82.6m
86.0m
1
6
t
o
8
8
1
0
1 S
t
a
27
(disused)
3
3
1
8
9
5
T
r
a
c
k
5
7
1
5
P
a
t
h
5
9
6
1
8
2
3
G
r
a
i
g
y
82.9m
3
3
L
o
c
k
4
1
Llygad y Ffynnon
D
a
r
r
e
n
Patagonia Farm
T
r
a
c
k
G
r
a
i
g
A
r
w
22
2
8
t
o
1
2
39
1
6
Levels
C
A
R
R
E
G
Y
R
A
F
O
N
7
4
1
4
1
1
O
W
E
N
'S
L
A
N
E
2
0
1
1
1
7
1
5
S
u
b
1
1
6
2
3
G
R
A
I
G
R
O
A
D
Gilfach Goch
192.5m
159.3m
8
Level
5
1
8
Club
T
h
e
2
1
8
64.9m
1
2
4
T
r
a
c
k
Cwar Pen-y-
44
87.2m
1
4
1
P
ath (um
)
Craig
Level
Arw
Levels
T
r
a
c
k
T
r
a
c
k
(
d
i
s
u
s
e
d
)
Quarries
8
2
9
7
1
0
2
1
3
Levels
Cemetery
Tir Garw
Mine
7
1
49
64
20
8
T
r
a
c
k
Gors-y-garamod
Level
T
r
a
c
k
156.7m
Farm
Gilfach-yr-haidd
Wood
158.0m
173.7m
T
r
a
c
k
T
r
a
c
k
Cwar
(disused)
T
r
a
c
k
T
r
a
c
k
T
r
a
c
k
(disused)
(disused)
Carreg Pentwyn Farm
T
r
a
c
k
P
a
th
(u
m
)
Tra
ck
Pen-y-graig
T
ra
ck
T
r
a
c
k
(disused)
3
(disused)
El
4
2
4
20
1
0
8
S
h
i
n
g
l
e
T
r
a
c
k
9
9
2
8
Ynyscu House
S
h
i
n
g
l
e
4
7
1
Level
4
8
Vicarage
Y Darren
Widdon
335.4m
Sheepfold
T
r
a
c
k
E
a
r
t
h
w
o
r
k
s
Church
FB
S
h
i
n
g
l
e
30
1
7
1
6
Sta
5
B
4
5
9
9
1
2
Ty'r-graig
7
2
63.4m
4
2
7
6
62.2m
2
5
1
2
9
8
2
1
1
0
0
1
6
5
1
1
9
79
FB
Quarries
FB
Shingle
8
8
Sheepfold
2
3
4
T
r
a
c
k
1
5
4
Sub
4
2
23
Ynys-glan-Tawe
5
7
4
5
2
1
7
176.7m
1
Levels
3
6
0
Alltygrug
62
P
E
N
-Y
R
-A
L
L
T
5
3
6
7
1
3
5
T
e
g
F
a
n
(covered)
8
1
.9
m
8
7
79
8
4
4
Ty'rwaun
2
1
5
335.3m
(disused)
Track
Mast
Mast
T
r
a
c
k
T
r
a
c
k
(disused)
Farteg Hill
344.5m
Playing Fields
2
5
G
l
y
n
V
i
e
w
LB
Cottage
G
L
A
N
T
W
R
C
H
2
Weir
1
Ynys-Cedwyn
1
3
Weir
2
S
M
6
7
2
G
L
A
N
T
A
W
E
P
K
27
4
7
2
1
1
1
1
4
4
1
Cottage
7
1
0
66.7m
2
7
5
9
15
(PH)
(
R
e
s
i
d
e
n
t
i
a
l
H
o
m
e
)
Surgery
4
0
12
C
ott
5
0
The All Black's Arms
3
8
Hall
Garage
4
4
Coed
7
5
3
2
1
5
8
72.1m
41
1
5
Gurnos
24
94
FB
82.3m
1
LB
Home Farm
SW
AN
LA
N
E
P
a
t
h
(
u
m
)
44
2
6
1
0
3
6
19
8
1
3
3
3
5
2
1
W
I
N
D
R
O
A
D
1
1
1
1
4
P
a
t
h
(
u
m
)
(disused)
2
0
2
5
Track
(disused)
9
2
7
6
29
1
0
a
8
0
1
0
74.2m
C
lu
b
Church
T
r
a
c
k
6
5
5
3
Aber-twrch
Level
64.8m
7
59.9m
4
4
53
1
8
Stone
3
1
1
A
4
0
6
7
T
ra
c
k
Shingle
T
ra
c
k
S
W
A
N
F
I
E
L
D
/
M
A
E
S
A
L
A
R
C
H
5
1
2
4
8
2
8
35
T
A
N
-Y
-F
A
R
T
E
G
1
3
6
5
8
3
H
E
O
L
T
U
D
O
R
/
T
U
D
O
R
S
T
R
E
E
T
6
Lodge
1
8
1
6
1
1
8
8
4
H
a
l
l
1
2
P
a
t
h
(
u
m
)
A
4
0
6
7
9
5
67
4
0
4
4
T
r
a
c
k
3
W
o
r
k
s
1
Path
N
e
w
G
urnos
67.6m
5
P
O
1
(disused)
Ystalyfera
2
3
1
2
9
1
CLEES
LB
102.5m
1
O
L
D
W
E
R
N
R
O
A
D
87.1m
1
0
9
3
8
4
8
14
Club
41
29
62.9m
1
2
5
9
L
B
73
8
4
6
4
9
4
.
6
m
1
3
3
2
2
3
8
7
5
7
0
1
2
P
a
t
h
(
u
m
)
2
0
132.2m
8
5
6
E
l
S
u
b
S
t
a
L
O
W
E
R
W
E
R
N
R
O
A
D
Avonsbrie
Meadow Vale
100.2m
Level
1
0
2
2
8
5
9
2
7
2
0
2
6
M
IN
Y
R
A
FO
N
107
D
e
r
l
w
y
n
Pant-y-gwanyd
2
3
28
Wern House
139.4m
3
0
2
4
7
2
Office
4
7
5
5
0
P
R
O
S
P
E
C
T
P
L
A
C
E
1
0
6
1
7
2
8
T
w
y
n
e
g
lu
r
2
a
8
6
A
4
0
6
7
1
a
1
9
5
4
1
3
LB
37
1
2
P
a
th
(u
m
)
D
E
E
L
E
Y
R
O
A
D
1
1
1
a
9
7
6
2
5
gwanyd Row
3
3
17
Ynisgeinon House
P
a
t
h
(
u
m
)
P
a
th
(
u
m
)
7
5
6
4
1
Level
Ty Gwyn
Ynisgeinon Farm
25
170.1m
1
TCB
G
r
a
i
g
A
r
w
1
0
2
1
8
2
6
Pant-y-
C
Y
F
Y
N
G
R
O
A
D
Sorting
4
2
5
9
59.0m
1
1
3
0
161.2m
5
3
8
3
4
1
2
4
4
101.5m
3
6
B
4
5
9
9
1
0
5
27
13
7
4
Green Croft
4
5
P
W
7
100.6m
Level
2
7
Mast
1
t
o
8
5
1
0
0
P
a
t
h
(
u
m
)
2
9
8
6
114.1m
2
1
172.7m
FFO
RDD EM
LYN
1
9
3
1
1
9
1
112.2m9
7
4
9
1
1
3
4
8
1
1
8
110.1m
100.9m
2
4
1
2
6
3
8
1
3
6
1
8
LB
3
7
T
r
a
c
k
TCB
P
E
N
-Y
R
-G
R
U
G
1
2
3
1
5
1
4
Level
2
6
2
1
3
LB
1
1
6
1
Cattle Grid
197.7m
3
9
4
7
5
1
Meadow Lodge
2
6
3
Tip
(disused)
5
Sunnybank
7
3
1
1
2
22
2
8
4
7
4
7
6
2
4
162.3m
8
8
40
T
r
a
c
k
8
4
A
L
L
T
Y
G
R
U
G
R
O
A
D
/
H
E
O
L
A
L
L
T
Y
G
R
U
G
2
8
2
7
House
187.6m
1
1
5
183.9m
L
i
b
y
1
0
0
.
8
m
(disused)
1
2
1
1
3
LB
2
9
1
2
8
3
3
P
a
th
(u
m
)
5
1
3
1
1
7
1
1
4
3
T
r
a
c
k
1
2
5
8
Allt-y-grug
Seasons
2
0
7
1
3
Islwyn
118.7m
6
5
87.2m
2
4
9
3
0
2
5
1
0
4
39
12
1
1
4
5
1
8
91.7m
50
(disused)
4
6
1
0
0
57
3
8
Four
7
Court
6
4
5
0
68
70
6
5
1
1
Y
G
IL
F
A
C
H
Pits
24
1
1
8
.
6
m
8
6
(disused)
2
4
16
4
B
R
O
N
Y
R
A
L
L
T
2
1
4
214.6m
3
4
140.3m
6
1
1
67
C
L
Y
N
G
W
Y
N
R
O
A
D
16
3
3
B
R
Y
N
-Y
-G
R
U
G
88
T
W
Y
N
-
Y
R
-
Y
S
G
O
L
1
to
5
7
1
7
2
20
T
ra
c
k
223.6m
201.8m
173.6m
Reservoir
1
2
1
1
L
O
N
T
A
N
Y
W
E
N
/ T
A
N
Y
W
E
R
N
L
A
N
E
Tra
ck
1
1
5
5
9
M
IL
B
O
R
O
U
G
H
R
O
A
D
/ H
E
O
L
M
IL
B
O
R
O
U
G
H
Crymlyn
8
1
1
9
1
6
7
0
5
4
5
6
1
6
a
Ty Gwyn-bach
Milborough
2
0
Tip
1
0
5
.
2
m
FB
M
I
N
Y
F
F
O
R
D
D
8
7
L
o
c
k
E
l
Ruin
Pantteg
S
u
b
S
t
a
109.0m
119.5m
Pantteg
1
3
118.0m
Hall
Wern
Oleu
20
6
5
Shelter
6
7
1
0
1
2
3
Burial Ground
(
d
i
s
u
s
e
d
)
C
i
l
b
r
w
y
n
Pantteg
2
0
5
/ Ynyscedwyn Ironworks Park
Rhoscerdd
Saron
Recreation Ground
Parc Gwaith Hearn Ynyngedwyn
S
h
e
l
t
e
r
S
h
e
l
t
e
r
1 to 4
H
A
F
A
N
C
L
O
S
E
8
1
9
Tank
O
f
f
ic
e
s
110.9m
1
8
C
l
i
n
i
c
1
4
63
Villas
1
2
0
G
o
v
t
T
y
G
w
y
n
2
9
Depot
Depot
12
61
P
a
lle
g
P
la
c
e
2
1
0
1
6
a
7
1
Ty Afal
E
l S
u
b
S
ta
P
a
th
(u
m
)
65
1
6
63
Heap
(dis)
Heap
(dis)
1
9
P
a
t
h
(
u
m
)
(dis)
FB
Caeralem
(dis)
37
27
Ty-Ni
Graig-arw
Penlan-Fach
Coed
Nant-y-Mynydd
Maes y Dderwen
41
125.1m
9
3
Y Wern
Primary School
P
a
th
(u
m
)
P
a
t
h
(
u
m
)
Heap
(dis)
Heap (dis)
Heap
(dis)
Heap
(dis)
Shaft
(dis)
Ysgol Gymraeg Dyffryn Glowyr
Weir
Ford
Weir
Weirs
P
a
t
h
Mast (telecommunication)
The Nook
C
W
R
T
Y
G
L
O
C
H
Ty Gardd
4
S
C
H
O
O
L
R
O
A
D
H
E
O
L
Y
R
Y
S
G
O
L
/
G
L
A
N
T
W
R
C
H
CO
ED
LA
N
H
E
O
L
A
A
R
O
N
GLANNANT TERRACE
GLA
NN
AN
T T
ER
RA
CE
P
E
N
Y
W
E
R
N
S
A
I
N
T
D
A
V
I
D
'
S
R
O
A
D
Ysgol Gymraeg Ystalyfera
1 to 35
Ystalyfera Rugby Club
M
aes-Y
-D
arren
6
2
5
6
1
1
0
5
7
5
1
7
80.1m
G
LAN Y
R A
FO
N
G
L
A
N
Y
R
A
F
O
N
G
L
A
N
Y
R
A
F
O
N
G
L
A
N
Y
R
A
F
O
N
G
L
A
N
Y
R
A
F
O
N
T
r
a
c
k
CG
P
a
th
(u
m
)
P
a
t
h
C
L
A
R
E
R
O
A
D
/
H
E
O
L
C
L
A
R
E
B
u
n
g
a
lo
w
Row
ESS
33
T
C
B
3
1
26
1
1
5
1
3
2
4
Bank
5
3
3
3
5
2
5
0
2
6
1
4
H
is
to
n
3
7
4
2
Office
Woodlands
P
a
n
t
t
e
g
C
a
p
e
l
67.4m
60.6m
25
23
5
60.6m
3
6
S
h
e
l
t
e
r
29
61.2m
35
Play Area
Play Area
Play Area
TCB
PO
4
3
5
1
0
1
3
9
8
2
7
9
7
3
6
Shelter
20
Filling Station
1
to
7
Cwrt
Gorof
Ruin
S
h
e
l
t
e
r
S
h
e
l
t
e
r
S
h
e
l
t
e
r
P
a
t
h
(
u
m
)
Play Area
Apostolic
Church
S
h
e
l
t
e
r
S
T
R
Y
D
N
E
W
Y
D
D
/
N
E
W
S
T
R
E
E
T
H
E
O
L
E
G
L
W
Y
S
/
C
H
U
R
C
H
R
O
A
D
S
h
e
lt
e
r
S
h
e
l
t
e
r
(Sch)
P
A
N
T
Y
F
F
Y
N
N
O
N
T
E
R
R
A
C
E
/
T
E
R
A
S
P
A
N
T
Y
F
F
Y
N
N
O
N
Shelter
Sh
elte
r
El Sub Sta
Ruin
Ruin
S
h
e
l
t
e
r
s
S
h
e
l
t
e
r
P
a
th
(u
m
)
LB
Play Area
El Sub Sta
FB
P
a
t
h
Bowling Green
4
9
B4599
B
4
5
9
9
5
0
Wern Fawr
4
1
H
E
O
L
G
L
A
N
R
H
Y
D
/
G
L
A
N
R
H
Y
D
R
O
A
D
El Sub Sta
Cricket Ground
Recreation Ground
C
O
M
M
E
R
C
I
A
L
S
T
R
E
E
T
/
S
T
R
Y
D
M
A
S
N
A
C
H
O
L
Z
O
A
R
R
O
A
D
/
H
E
O
L
Z
O
A
R
W
E
R
N
R
O
A
D
/
H
E
O
L
Y
W
E
R
N
C
L
A
R
E
R
O
A
D
/
G
O
U
G
H
R
O
A
D
/
H
E
O
L
G
O
U
G
H
Play Area
Playing Field
Recreation Ground
Play Area
El Sub Sta
El Sub Sta
Cornerways
Lighting Tower
C
o
a
c
h
H
o
u
s
e
S
h
e
l
t
e
r
Tank
L
in
e
o
f
P
o
s
t
s
P
ath (um
)
Lighting Towers
Pavilion
ESS
ESS
Swansea Valley Business Park
Sports Ground
Maes-y-coed House
5
W
o
rks
W
o
r
k
s
Workshops
C
h
a
p
e
l
Ystradgynlais
1
9
Track
P
a
t
h
(
u
m
)
Playing Field
H
E
O
L
C
L
A
R
E
1
2
1
8
Track
2
7
1
1
53a
1
7
L
L
Y
S
C
A
M
B
R
I
A
N
P
a
t
h
Pen-y-graig-arw
(disused)
Pen-y-graig
(disused)
Sta
1
1
Burial Ground
T
r
a
c
k
Crynant Forest
T
r
a
c
k
T
r
a
c
k
T
r
a
c
k
T
r
a
c
k
F
F
O
R
D
D
D
A
N
Y
G
R
A
I
G
3
1
L
L
Y
S
H
A
R
R
Y
1
2
6
3
5
1
1
L
L
Y
S
Y
N
Y
S
G
E
I
N
O
N
2
3
7
1
2
4
1
2
6
8
Posts
1
7
9
1
3
2
Posts
1
3
1
L
L
Y
S
R
H
A
E
A
D
R
F
F
O
R
D
D
Y
G
L
O
W
Y
R
3
1
1
9
2
4
1
18
4
5
L
L
Y
S
Y
R
A
F
O
N
1
4
8
1
2
4
1
1
3
2
8
3
3
0
3
2
7
4
9
Cysgod
R
D
P
E
N
T
W
Y
N
Midland
Rivendell
GG
El Sub Sta
C
W
R
T
Y
G
A
M
L
A
S
Y
Mynydd
S
u
r
g
e
r
y
4
3
3
2
6
3
2
1
3
2
9
28
4
6
ESS
7
1
0
Woodlands Business Park
/ Parc Busnes Coed Cedwyn
The Willows
4
Ppg Sta
2
9
2
2
(Sch)
2
8
4
8
2
1
3
8
1
4
1
3
2
4
I
n
d
u
s
t
r
ia
l
E
s
t
a
t
e
S
N
O
W
T
E
R
R
A
C
E
ESS
1
a
3
9
3
0
4
3
25
7
2
2
3
1
2
Ysgol Bro Tawe
L
i
g
h
t
i
n
g
T
o
w
e
r
s
Ysgol Maesydderwen
or Maesydderwen School
F
F
O
R
D
D
Y
R
A
F
O
N
Gardens
L
i
g
h
t
i
n
g
T
o
w
e
r
s
Path
El Sub Sta
2
T
e
n
n
i
s
C
o
u
r
t
C
o
m
m
u
n
i
t
y
C
e
n
t
r
e
1
6
1
6
5
3
78a
4
Filling Station
Tanks
6
G
O
R
O
F
R
O
A
D
75.3m
Golwg y Cwm
121.0m
Danygoeden
Y
G
I
L
W
E
R
N
L
y
n
s
d
a
l
e
85
87
2
0
1
G
O
L
W
G
Y
M
Y
N
Y
D
D
3
8
a
2
9
1
2
62
5
Golwg
Y
Darren
9
3
4
3
1
1
6
8
3
1
2
9
1
1
1
0
1
M
A
E
S
-Y
-C
O
E
D
2
0
6
9
1
1
5
126.8m
1
2
1
8
1
3
2
0
1
9
1
4
1
6
P
a
t
h
(
u
m
)
P
A
R
K
P
a
t
h
(
u
m
)
5
1
1
3
1
7
56.6m
5
1
2
4
2
1
Terrace
Chrisgar
Ystradgynlais
Community
Hospital
3
0
2
8
2
1
2
1
3
7
3
1
3
1
4
1
5
57
T
r
a
c
k
Picnic Area
8
0
7
2
55
Pavilion
6
4
5
2
6
2
7
4
S
h
i
n
g
l
e
Heap
Sewage Works
Workings (dis)
T
ra
ck
T
r
a
c
k
Pa
th
(u
m)
T
r
a
c
k
Workings (dis)
Workings (dis)
Tank
Heap
Heap (dis)
Heap (dis)
Workings (dis)
C
a
r
P
a
r
k
G
l
a
n
-
y
r
-
a
f
o
n
1
4
FB
4
0
3
4
Twrch
Bridge
G
R
A
I
G
Y
F
F
O
R
E
S
T
2
PANTYFFYNNON
Glan-rhyd
PANTYFFYNNON
4
1
1
5
1
C
y
c
le
W
a
y
W
e
i
r
Cwm Wanderers
(Football Ground)
2
6
a
2
6
1
1
Ystradgynlais
Sports Centre
99.8m
Shelters
68.5m
D
i
s
m
a
n
t
l
e
d
R
a
i
l
w
a
y
L
a
y
-
b
y
74.8m
2
5
b
5
a
L
L
Y
S
G
R
A
IG
A
R
W
1
4
Public Recycling Facility
(
P
H
)
81.2m
91.6m
86.6m
88.7m
E
T
L
El Ps
ETL
El Ps
El Ps
E
T
L
E
T
L
E
T
L
P
ip
e
lin
e
E
T
L
E
T
L
El Ps
E
T
L
E
T
L
E
T
L
E
T
L
El Ps
ETL
El Ps
El Ps
E
T
L
E
T
L
E
T
L
Mast (TV)
El Ps
El Ps
E
T
L
Issues
Issues
Issues
Springs
Issues
Issues
Issues
Issues
Issues
I
s
s
u
e
s
Issues
Issues
Issues
Pond
Spring
D
r
a
in
D
r
a
i
n
Issues
Pond
Pond
Pond
Pond
Feeder (disused)
D
r
a
i
n
Pond
Sinks
Sinks
Pond
Waterfall
Issues
Issues
I
s
s
u
e
s
Sinks
Issues
D
r
a
i
n
O
u
t
f
a
l
l
R
i
v
e
r
T
a
w
e
Issues
Waterfall
Sinks
Waterfall
Sinks
Issues
Pond
Waterfall
Issues
Issues
Sinks
D
r
a
i
n
Issues
D
r
a
i
n
Sinks
Issues
Sinks
(disused)
Issues
Spring
Sinks
Issues
Sinks
D
r
a
i
n
Issues
Issues
D
r
a
i
n
Spring
Issues
D
r
a
i
n
D
r
a
in
Lock
Sinks
D
r
a
i
n
Ford
Issues
Pond
Issues
Sinks
Issues
Spring
Pond
D
r
a
i
n
D
r
a
i
n
Issues
Issues
D
r
a
i
n
Spring
Drain
Pond
Issues
D
r
a
in
Issues
Issues
D
r
a
in
Spring
Spring
Issues
Issues
Issues
A
fo
n
T
w
rc
h
Spring
Pond
D
ra
in
D
r
a
in
Spring
Ford
Spring
Spring
Issues
Drain
D
ra
in
D
r
a
i
n
Spring
Pond
Pond
Spring
Pond
Spring
Spring
Pond
P
o
n
d
Issues
Spring
Spring
P
o
n
d
Drain
Pond
A
fo
n
T
w
r
c
h
Issues
Pond
Issues
D
r
a
i
n
A
f
o
n
T
w
r
c
h
Spring
Sinks
Issues
Pond
Sinks
Pond
A
fo
n
T
a
w
e
/ R
iv
e
r
T
a
w
e
Issues
D
r
a
i
n
Issues
Sinks
D
r
a
i
n
Afon T
aw
e / R
iver T
aw
e
Pond
A
f
o
n
T
a
w
e
/
R
i
v
e
r
T
a
w
e
Afon Tawe / River Tawe
Ford
Waterfalls
Waterfall
Collects
Spreads
Spreads
Collects
Collects
Collects
Collects
Ford
Ford
Spreads
Collects
Ford
Ford
Ford
Ford
Ford
D
r
a
i
n
Pond
D
ra
in
Spreads
/
A
f
o
n
T
a
w
e
Collects
Collects
Collects
Collects
Ford
Spreads
Collects
Spreads
D
r
a
i
n
Client:
Project:
Drg Title:
Date:
Drg No.
tuliptulip
engineering consultancy
LIDAR PLAN
09.04.2020
Status:
PLANNING
J009/001 Rev.
SWANSEA VALLEY
IND. EST. FCA
CB3 CONSULT LTD
Scale:1:10,000
-
Size:A3
Rev Date
34 Culfor Road, Loughor, Swansea SA4 6TY
tel: 01792 893407 mob: 07843 491524
w: www.tulipengineering.co.uk
DLO
24/03/2016
1/250 @ A0
Drawn by
Date
Scale
Drawing Number
Contract
10007/001/CD/DLO
Mr Paul James
Swansea Valley Business Park
Glanyrafon Roundabout
Ystalyfera
SA9 2EE
Topographical Survey
1 Heol Yr Ysbyty, Castle View, Caerphilly CF83 1TA
Mobile- 07919 326969 Office- 02920 886120
Email- [email protected]
www.darenoliversurveying.com
Daren OliverCivil Eng Services Ltd
THE TOTAL ON-SITE ENGINEERING SOLUTION
Swansea Valley Business Park, Ystalafera Project Number: J009 Document Reference: FCA/01
https://d.docs.live.net/9692ee99776ac28f/Documents/Tulip Engineering Consultancy/Jobs/J009 - Swansea Valley Ind Est FCA/Production/Data - Internal/FCA - Swansea Valley Ind Est.docx
B. Architectural Site Plan, 3D Image
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Swansea Valley Business Park, Ystalafera Project Number: J009 Document Reference: FCA/01
https://d.docs.live.net/9692ee99776ac28f/Documents/Tulip Engineering Consultancy/Jobs/J009 - Swansea Valley Ind Est FCA/Production/Data - Internal/FCA - Swansea Valley Ind Est.docx
C. Flood Maps
Ceir rhestr lawn o delerau ac amondau yn https://naturalresources.wales/rhybuddsafonol neu drwy gysylltu ag [email protected]. A full list of terms and condiitions is available from the https://naturalresources.wales/StandardNotice or by contacting [email protected] © Crown copyright and database rights 2017 Ordnance Survey 100019741. Geological Mapping: British Geological Survey ©NERC. Centre for Ecology & Hydrology © NERC (CEH). Defra and Met Office © Crown copyright. © Cranfield University. © James Hutton Institute. Land & Property Services © Crown copyright and database right.
1:
12/04/2020
Dyddiad / Date
Map Title
5,001
Map Perygl Llifogydd / Flood Risk Map
Graddfa / Scale
0.13
Kilometers
0.3
British_National_Grid
00.3
Allwedd / Map KeyZone C1
Zone C2
Zone B
Zone A
Ceir rhestr lawn o delerau ac amondau yn https://naturalresources.wales/rhybuddsafonol neu drwy gysylltu ag [email protected]. A full list of terms and condiitions is available from the https://naturalresources.wales/StandardNotice or by contacting [email protected] © Crown copyright and database rights 2017 Ordnance Survey 100019741. Geological Mapping: British Geological Survey ©NERC. Centre for Ecology & Hydrology © NERC (CEH). Defra and Met Office © Crown copyright. © Cranfield University. © James Hutton Institute. Land & Property Services © Crown copyright and database right.
1:
12/04/2020
Dyddiad / Date
Map Title
5,001
Map Perygl Llifogydd / Flood Risk Map
Graddfa / Scale
0.13
Kilometers
0.3
British_National_Grid
00.3
Allwedd / Map KeyMain Rivers
Flood Defences
Areas Benefiting from Flood Defences
Flood Storage Areas
Floodmap Flood Zone 3
Floodmap Flood Zone 2
Path (um)
Path (um)
LB
Path (um)
P
a
t
h
(
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m
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igfran
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1
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1
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86.0m
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L
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1
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D
a
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Patagonia Farm
T
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a
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r
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39
1
6
Levels
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G
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3
G
R
A
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G
R
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A
D
8
Level
5
1
8
Club
T
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2
1
8
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1
2
4
Cwar Pen-y-
44
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1
4
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Craig
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(
d
i
s
u
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d
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Quarries
8
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9
7
1
0
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1
3
Levels
Cemetery
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7
1
49
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20
8
(disused)
T
r
a
c
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T
r
a
c
k
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ath (um
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Track
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CLEES
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g
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4
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2
5
Ynisgeinon House
Ynisgeinon Farm
G
r
a
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g
A
r
w
C
Y
F
Y
N
G
R
O
A
D
59.0m
101.5m
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1
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5
100.6m
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1
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0
2
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9
1
2
6
1
1
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7
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r
S
h
e
l
t
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r
8
1
9
(dis)
(dis)
37
27
Graig-arw
41
125.1m
9
3
Ford
G
L
A
N
Y
R
A
F
O
N
G
L
A
N
Y
R
A
F
O
N
Row
Office
Woodlands
P
a
n
t
t
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g
C
a
p
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l
60.6m
TCB
Shelter
20
Ruin
S
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e
r
P
a
t
h
(
u
m
)
S
h
e
l
t
e
r
S
T
R
Y
D
N
E
W
Y
D
D
/
N
E
W
S
T
R
E
E
T
H
E
O
L
E
G
L
W
Y
S
/
C
H
U
R
C
H
R
O
A
D
P
A
N
T
Y
F
F
Y
N
N
O
N
T
E
R
R
A
C
E
/
T
E
R
A
S
P
A
N
T
Y
F
F
Y
N
N
O
N
Ruin
S
h
e
l
t
e
r
s
P
a
th
(u
m
)
LB
FB
4
9
5
0
Play Area
Playing Field
Recreation Ground
Swansea Valley Business Park
1
9
1
2
1
8
2
7
1
1
1
7
L
L
Y
S
C
A
M
B
R
I
A
N
Pen-y-graig-arw
(disused)
1
1
F
F
O
R
D
D
D
A
N
Y
G
R
A
I
G
3
1
L
L
Y
S
H
A
R
R
Y
1
2
6
3
5
1
1
L
L
Y
S
Y
N
Y
S
G
E
I
N
O
N
2
3
7
1
2
4
1
2
6
8
1
7
9
1
3
2
1
3
1
L
L
Y
S
R
H
A
E
A
D
R
F
F
O
R
D
D
Y
G
L
O
W
Y
R
3
1
1
9
2
4
1
L
L
Y
S
Y
R
A
F
O
N
1
4
8
1
2
4
1
1
4
6
The Willows
2
9
2
2
2
8
4
8
2
1
3
8
1
4
1
3
2
4
3
9
3
0
4
3
25
7
2
2
3
1
2
Danygoeden
2
0
1
G
O
L
W
G
Y
M
Y
N
Y
D
D
2
62
5
1
1
6
2
0
6
1
1
5
2
1
2
0
1
9
1
4
1
6
P
a
t
h
(
u
m
)
5
1
7
5
1
2
4
2
1
3
0
2
8
2
1
2
1
3
7
3
3
1
57
8
0
7
2
55
6
4
5
2
6
2
7
4
S
h
i
n
g
l
e
Heap
T
r
a
c
k
T
r
a
c
k
Heap
C
a
r
P
a
r
k
G
l
a
n
-
y
r
-
a
f
o
n
1
4
FB
4
0
3
4
G
R
A
I
G
Y
F
F
O
R
E
S
T
2
PANTYFFYNNON
PANTYFFYNNON
4
1
1
99.8m
68.5m
74.8m
2
5
b
5
a
L
L
Y
S
G
R
A
IG
A
R
W
1
4
88.7m
El Ps
El Ps
E
T
L
E
T
L
El Ps
El Ps
E
T
L
E
T
L
El Ps
D
r
a
i
n
Pond
Sinks
Sinks
Pond
Waterfall
Issues
Issues
I
s
s
u
e
s
Sinks
Issues
D
r
a
i
n
O
u
t
f
a
l
l
R
i
v
e
r
T
a
w
e
Issues
Waterfall
Sinks
Waterfall
Sinks
Pond
Issues
Sinks
D
r
a
i
n
Issues
D
r
a
i
n
Sinks
Issues
Sinks
(disused)
Issues
Spring
Sinks
Issues
Sinks
D
r
a
i
n
Issues
Issues
D
r
a
i
n
Spring
Issues
D
r
a
i
n
D
r
a
in
Lock
Sinks
D
r
a
i
n
Ford
Sinks
D
r
a
i
n
Issues
Issues
D
r
a
i
n
Spring
Spring
Pond
Issues
A
fo
n
T
a
w
e
/ R
iv
e
r
T
a
w
e
Issues
D
r
a
i
n
Issues
Sinks
D
r
a
i
n
Waterfalls
Collects
Collects
Collects
Ford
Ford
Ford
Ford
Ford
D
r
a
i
n
Pond
D
rain
/
A
f
o
n
T
a
w
e
Spreads
S
u
b
w
a
y
PW
6
3
31
3
1
1
19
6
1
9
3
3
3
0
5
CO
LLE
GE
R
OW
Mynydd
Coch
Bowling Green
Caringdale
A
m
b
u
l
a
n
c
e
T
r
a
c
k
(disused)
Hall
67.5m
4
Penrhiwfarteg
3
1
9
96.7m
128
S
t
a
t
i
o
n
P
a
t
h
(
u
m
)
9
1
2
3
5
7
t
o
6
0
12
El Sub Sta
3
6
P
a
t
h
(
u
m
)
1
7
18
6
7
15
1 to 23
84
99
108
1
4
8
6
4
71
20
Sunny
Bank
80.2m
4
2
2
2
16
7
5
Glan-rhyd
66.2m
Level
5
P
a
t
h
(
u
m
)
Glan-rhyd
Swn y Nant
69.0m
R
H
Y
D
W
E
N
T
r
a
c
k
1
Bridge
1
1
6
Tank
8
120.8m
8
9
7
1
0
6
111.6m
Farteg-fach
Cottage
Levels
1
1
2
Park House
6
(disused)
2
9
T
r
a
c
k
Glan-rhyd
4
The Elms
Farteg-uchaf
1
6
122.6m
52
62
27
2
3
Garage
7
9
T
y
n
e
d
a
l
e
201 to 207
127
7
7
Arosfa
Pont Aur
Erwlas
A
4
0
6
7
B
l
a
e
n
a
n
t
H
o
74.0m
PO
NT AUR
1
6
S
p
r
i
n
g
f
i
e
l
d
1
4
TCB
N
e
u
a
d
d
llw
y
d
78b
4
6
5
5
69.5m
7
1
8
TR
A
W
S
FF
O
R
D
D
17
100
D
d
o
l
w
e
n
5
4
8
HE
OL G
LA
NT
AW
E
101a
2
8
4
7
1
2
6
1
3
0
6
Maesydderwen
4
2
Cartref
5
S
h
e
lt
e
r
Drift
Tennis Courts
D
u
m
f
r
i
e
s
P
l
a
c
e
125a
5
4
5
1
19
y
r
E
o
s
1
5
Glyn Dderwen
97
6
76b
LB
4
1
2
3
1
74.7m
75.7m
7
6
1
7
1
3
77a
4
7
37
2
1
110b
1
25
Ynyscedwyn
67
1
9
71
62
8
Maes-
110a
3
125
1
2
6
44
77b
H
E
O
L
Y
N
Y
S
C
E
D
W
Y
N
/
Y
N
Y
S
C
E
D
W
Y
N
R
O
A
D
Club
El S
ub S
ta
1
13
S
w
n
18
1
1
5
17
5
6
3
0
0
1
5
M
A
E
S
Y
D
D
E
R
W
E
N
G
D
N
S
2
3
M
a
e
s-y-G
la
n
W
I
L
L
I
A
M
S
T
R
E
E
T
y-coed
S
h
e
l
t
e
r
3
Golwg
48
(disused)
1
68
101b
9
4
1
1
8
1
31
1
4
23
84.5m
Cottage
4
0
Y
B
E
R
L
L
A
N
TCB
1
1
Jones
54
1
5
2
76.2m
7
1
5
2
3
Y Bwthyn
H
a
z
e
l
d
e
n
e
7
9
Superstore
1
4
4
3
9
2
0
5
9
B
E
T
H
E
L
R
O
A
D
3
2
The
1
0
2
4
G
u
rn
o
s
43
4
5
85.1m
2
1
1
3
GP
4
0
Works
2
4
65
4
H
e
n
F
e
lin
E
l
S
u
b
S
t
a
1
1
G
O
R
O
F
R
O
A
D
6
7
P
ath (um
)
P
H
Cottage
H
o
u
s
e
1
3
2
1
Subway
3
7
Moel-Llys
G
l
a
n
y
r
o
n
e
n
7
6
69.0m
2
6
E
r
w
H
y
d
r
e
f
42
6
2
3
92
The
1
4
R
o
s
e
C
o
t
t
a
g
e
1
8
49
4
7
7
1
1
4
Erw
Oaks
A 4068
6
12
1
68.6m
G
L
A
N
T
A
W
E
P
A
R
K
El Ps
G
arage
1
3
3
C
apital B
ldgs
2
3
1
1
3
9
1
5
C
R
O
E
S
F
F
Y
R
D
D
H
o
u
s
e
s 2
6
El Sub Sta
1
4
S
A
I
N
T
D
A
V
I
D
S
R
O
A
D
Dan-y-
Depot
3
3
8
H
E
O
L M
E
U
R
IG
67.6m
8
1
3
T
I
R
B
A
C
H
R
O
A
D
71.0m
1
8
C
W
M
P
H
I
L
R
O
A
D
W
o
r
k
s
75.6m
1
5
19
Glanyronen
1
2
26
El Sub Sta
G
U
R
N
O
S
R
O
A
D
H
a
ll
1
1
6
2
B
4
5
9
9
4
5
83.7m
5
6
C
O
M
M
E
R
C
IA
L S
T
R
E
E
T
2
7
2
3
1
Llys F
redrick
Tel Ex
GP
1
7
4
14
1
0
3
6
1
3
1
2
a
S
h
in
g
le
2
S
P
E
N
C
E
R
T
E
R
R
A
C
E
2
5
3
81.0m
2
0
2
1
1
4
6
Glan-Twrch
1
70.5m
Clun-gwyn
1
7
a
1
4
11
3
6
FB
1
7
6
1
Glantwrch
5
0
79.2m
8
1
6
6
4
8
G
L
A
N
T
A
W
E
6
G
O
U
G
H
A
V
E
N
U
E
7
1
9
1
9
4
Dan-y-
2
1
8
T
C
B
8
4
Pandy
Fair
24
Millfield
4
2
W
a
ysid
e
1a
G
U
R
N
O
S
R
O
A
D
Gurnos
4
6
1
9
2
22
T
a
n
-
y
-
c
o
e
d
1
4
2
H
E
O
L
A
B
R
A
M
7
B
4
5
9
9
1
30
Pinetree Lodge
11
7
1
1
7
2
W
o
r
k
s
2
8
Y
r
-
H
e
n
-
B
o
n
t
1
5
9
2
67.8m
GP
Birkdale
4
1
79.6m
3
6
4
1
6
Wharf
67.1m
1
0
69.9m
9
4
4
Bungalow
5
1
3
3
1
5
a
El Ps
6
8
9
A
L
D
E
R
A
V
E
N
U
E
El Ps
6
6
90
Tank
T
r
a
c
k
Tank
1
0
Shelter
The Beeches
B
r
y
n
b
a
c
h
1
0
1 to 4
3
5
D
a
n
-y-C
o
e
d
Varteg
House
Brook
Lodge
Playground
Y
C
e
d
r
w
y
d
d
L
L
Y
S
Y
N
Y
S
C
E
D
W
Y
N
8
1
4
3
G
O
R
O
F
1
6
Oak Villas
P
a
th
(
u
m
)
(disused)
P
a
t
h
Outfall
Mast
C
y
c
l
e
P
a
t
h
C
y
c
le
P
a
t
h
1
3
1
5
T
r
a
c
k
M
a
e
s
g
w
y
n
Lighting Tower
C
y
c
l
e
P
a
t
h
5
5
107
/ Parc Menter
Ynyscedwyn
Enterprise Park
126b
126a
Llys-Swynol
27
2
4
1
3
5
5
D
e
l
f
a
n
L
l
e
c
h
w
e
d
d
T
r
a
c
k
7
10
9
El Sub Sta
E
l
S
u
b
S
t
a
N
e
w
l
y
n
T
A
W
E
P
A
R
K
3
5
3
3
4
102
Chy
76
5
2
67.8m
5
6
5
2
6
4
7
72.4m
73.7m
7
3
36
2
4
4
25
6
8
75
111
El Sub Sta
1
0
5
Club
G
l
a
n
n
a
n
t
H
o
Stand
1
3
6
1
6
P
a
t
h
13
8
8
7
P
a
t
h
(
u
m
)
6
8
7
1
0
8
3
1
W
A
D
E
A
V
E
N
U
E
1
2
0
8
8
1
3
6
9
Pol
2
89.1m
28
2
5
1
Heulwen
130.4m
V
I
N
E
R
O
W
167.6m
1
6
0
6
6
2
1
8
7
C
A
N
A
L
T
E
R
R
A
C
E
82.7m
7
D
A
R
R
E
N
R
O
A
D
P
a
t
h
(
u
m
)
5
3
1
0
1
3
6
Path (um
)
49
S
C
H
O
O
L
R
O
A
D
4
4
1
3
1
5
18
4
7
1
1
5
4
1
4
Path (um
)
W
e
r
n
V
i
l
l
a
s
Brynderwyn
130.4m
1
G
R
A
I
G
Y
M
E
R
C
H
E
D
Pavilion
P
E
N
Y
W
E
R
N
R
O
A
D
8
0
6
1
A
rn
o
ld
C
o
u
rt
65.9m
E
l
S
u
b
S
t
a
6
3
1
60
V
A
R
T
E
G
R
O
A
D
P
W
T
e
n
n
i
s
C
o
u
r
t
s
1
3
2
5
1
Bowling Green
24
59.8m
The Poplars
1
7
69
8
4
LB
1
2
0
4
6
1
2
2
6
2
4
7
4
P
H
7
T
H
E
G
A
R
D
E
N
S
4
W
E
R
N
W
O
O
D
R
O
A
D
1
2
5
a
1
1
0
3
7
2
7
64
5
3
E
l
S
u
b
S
t
a
8
7
3
3
9
P
H
1
8
6
2
3
1
99.1m
9
2
2
2
2
2
58.7m
6
5
6
2
1
8
Car Park
3
7
2
4
Y
N
Y
S
Y
D
A
R
R
E
N
R
O
A
D
/
H
E
O
L
Y
N
Y
S
Y
D
A
R
R
E
N
1
4
3
4
1
0
0
P
a
th
(u
m
)
1
7
1
5
39
1
1
4
1
7
C
y
s
t
a
n
o
g
Parc-y-Darren
7
2
P
a
t
h
(
u
m
)
8
1
S
u
n
n
y
v
ille
4
59.7m
(disused)
53
104.2m
1
2
1
2
1
1
2
2
M
a
e
s
-
y
-
w
e
r
n
1
0
1
4
8
3
7
5
a
56
24
5
6
2
4
5
28
1
5
1
3
7
G
L
A
N
-
Y
R
-
Y
S
G
O
L
4
1
42
27
El Sub Sta
60.9m
W
E
M
B
L
E
Y
R
O
A
D
4
1
5
2
4
1
3
3
0
165.5m
2
0
Meml
2
0
3
3
2
PH
W
O
O
D
M
A
N
S
T
E
R
R
A
C
E
1
5
4
0
2
7
16
3
6
7
1
6
5
1
F
F
O
R
D
D
G
L
A
N
D
W
R
7
9
4
1
4
1
7
2
0
2
2
Gilfach Goch
192.5m
159.3m
T
r
a
c
k
P
a
th
(u
m
)
Level
Levels
T
r
a
c
k
T
r
a
c
k
Tir Garw
T
r
a
c
k
Gors-y-garamod
Level
T
r
a
c
k
156.7m
Farm
Gilfach-yr-haidd
Wood
158.0m
173.7m
T
r
a
c
k
T
r
a
c
k
Cwar
T
r
a
c
k
(disused)
(disused)
Carreg Pentwyn Farm
T
r
a
c
k
Pen-y-graig
T
ra
ck
T
r
a
c
k
(disused)
3
(disused)
El
4
2
4
20
1
0
8
S
h
i
n
g
l
e
9
9
2
8
Ynyscu House
S
h
i
n
g
l
e
4
7
1
Level
4
8
Vicarage
Church
FB
S
h
i
n
g
l
e
3
0
1
7
1
6
Sta
5
B
4
5
9
9
1
2
Ty'r-graig
7
2
63.4m
4
2
7
6
62.2m
2
5
1
2
9
8
2
1
1
0
0
1
6
5
1
1
9
79
FB
FB
Shingle
8
8
2
3
4
T
r
a
c
k
1
5
4
Sub
4
2
23
Ynys-glan-Tawe
5
74
5
2
1
7
176.7m
1
Levels
3
6
0
Alltygrug
62
P
E
N
-Y
R
-A
L
L
T
5
3
6
7
1
3
5
T
e
g
F
a
n
(covered)
8
1
.9
m
8
7
7
9
8
4
4
Ty'rwaun
2
1
5
Playing Fields
2
5
G
l
y
n
V
i
e
w
LB
Cottage
G
L
A
N
T
W
R
C
H
2
Weir
1
Ynys-Cedwyn
1
3
Weir
2
S
M
6
7
2
G
L
A
N
T
A
W
E
P
K
27
4
7
2
1
1
1
1
4
4
1
Cottage
7
1
0
66.7m
2
7
5
9
15
(PH)
(
R
e
s
i
d
e
n
t
i
a
l
H
o
m
e
)
Surgery
4
0
12
C
ott
5
0
The All Black's Arms
3
8
Hall
Garage
4
4
Coed
7
5
3
2
1
5
8
72.1m
41
1
5
Gurnos
24
94
FB
82.3m
1
LB
Home Farm
S
W
A
N
LA
N
E
P
a
t
h
(
u
m
)
44
2
6
1
0
3
6
19
8
1
3
3
3
5
2
1
W
I
N
D
R
O
A
D
1
1
1
1
4
P
a
t
h
(
u
m
)
2
0
2
5
Track
(disused)
9
2
7
6
2
9
1
0
a
8
0
10
74.2m
C
lu
b
Church
T
r
a
c
k
65
5
3
Aber-twrch
Level
64.8m
7
59.9m
4
4
53
1
8
Stone
3
1
1
A
4
0
6
7
Shingle
T
ra
c
k
S
W
A
N
F
I
E
L
D
/
M
A
E
S
A
L
A
R
C
H
5
1
2
4
8
2
8
35
T
A
N
-Y
-F
A
R
T
E
G
1
36
5
8
3
H
E
O
L
T
U
D
O
R
/
T
U
D
O
R
S
T
R
E
E
T
6
Lodge
1
8
1
6
1
1
8
8
4
H
a
l
l
1
2
P
a
t
h
(
u
m
)
A
4
0
6
7
9
5
67
4
0
4
4
T
r
a
c
k
3
W
o
r
k
s
1
P
a
th
N
e
w
G
urnos
67.6m
5
P
O
1
(disused)
Ystalyfera
2
3
1
2
9
1
LB
102.5m
1
O
L
D
W
E
R
N
R
O
A
D
87.1m
1
0
9
3
8
4
8
14
Club
41
2
9
62.9m
1
2
5
9
L
B
73
8
4
6
4
9
4
.
6
m
1
3
3
2
2
3
8
7
5
7
0
1
2
P
a
t
h
(
u
m
)
132.2m
8
5
6
E
l
S
u
b
S
t
a
L
O
W
E
R
W
E
R
N
R
O
A
D
Avonsbrie
Meadow Vale
100.2m
2
8
5
9
2
7
2
0
2
6
M
IN
Y
R
A
FO
N
D
e
r
l
w
y
n
Pant-y-gwanyd
28
Wern House
139.4m
3
0
2
4
7
2
Office
4
7
5
5
0
P
R
O
S
P
E
C
T
P
L
A
C
E
1
0
6
1
7
28
2
a
1
a
1
9
5
4
1
3
37
1
2
P
a
th
(u
m
)
D
E
E
L
E
Y
R
O
A
D
97
6
gwanyd Row
3
3
17
P
a
t
h
(
u
m
)
P
a
th
(
u
m
)
7
5
6
4
1
Level
Ty Gwyn
2
5
170.1m
1
TCB
1
0
2
1
8
2
6
Pant-y-
Sorting
4
2
5
9
1
1
3
0
161.2m5
3
8
3
4
1
24
4
3
B
4
5
9
9
2
7
13
7
4
Green Croft
4
5
P
W
7
Level
2
7
1
t
o
8
P
a
t
h
(
u
m
)
2
9
8
6
114.1m
172.7m
FFO
RDD EM
LYN
3
1
1
9
1
112.2m
9
7
4
9
1
1
3
4
8
1
1
8
110.1m
100.9m
2
4
3
8
1
3
6
18
LB
3
7
T
r
a
c
k
TCB
P
E
N
-Y
R
-G
R
U
G
1
2
3
1
5
1
4
Level
2
6
2
1
3
LB
1
1
6
1
Cattle Grid
197.7m
3
9
4
7
5
1
Meadow Lodge
2
6
3
Tip
(disused)
5
Sunnybank
7
3
1
1
2
22
2
8
4
7
4
7
6
2
4
162.3m
8
8
40
T
r
a
c
k
8
4
A
L
L
T
Y
G
R
U
G
R
O
A
D
/
H
E
O
L
A
L
L
T
Y
G
R
U
G
2
8
2
7
House
187.6m
1
1
5
183.9m
L
i
b
y
1
0
0
.
8
m
(disused)
12
1
1
3
LB
2
9
1
2
8
3
3
P
a
th
(u
m
)
5
1
3
1
1
7
1
14
3
T
r
a
c
k
1
2
5
8
Allt-y-grug
Seasons
2
0
7
1
3
Islwyn
118.7m
6
5
87.2m
2
4
9
3
0
2
5
1
0
4
39
1
2
1
1
4
5
1
8
91.7m
50
(disused)
4
6
1
0
0
57
3
8
Four
7
Court
6
4
5
0
6
8
70
6
5
Y
G
IL
F
A
C
H
Pits
24
1
1
8
.
6
m
8
6
(disused)
2
4
16
4
B
R
O
N
Y
R
A
L
L
T
2
1
4
214.6m
3
4
140.3m
6
1
1
67
C
L
Y
N
G
W
Y
N
R
O
A
D
1
6
3
3
B
R
Y
N
-Y
-G
R
U
G
88
T
W
Y
N
-
Y
R
-
Y
S
G
O
L
1
to
5
7
1
7
2
20
T
ra
c
k
223.6m
201.8m
173.6m
Reservoir
1
2
1
1
L
O
N
T
A
N
Y
W
E
N
/ T
A
N
Y
W
E
R
N
L
A
N
E
Track
1
1
5
5
9
M
IL
B
O
R
O
U
G
H
R
O
A
D
/ H
E
O
L
M
IL
B
O
R
O
U
G
H
Crymlyn
8
1
1
9
1
6
7
0
5
4
5
6
1
6
a
Ty Gwyn-bach
Milborough
2
0
Tip
1
0
5
.
2
m
FB
M
I
N
Y
F
F
O
R
D
D
Ruin
109.0m
119.5m
1
3
118.0m
Hall
Wern
Oleu
20
6
5
6
7
1
0
1
2
3
Burial Ground
/ Ynyscedwyn Ironworks Park
Rhoscerdd
Saron
Recreation Ground
Parc Gwaith Hearn Ynyngedwyn
1 to 4
H
A
F
A
N
C
L
O
S
E
Tank
O
f
f
ic
e
s
110.9m
1
8
C
l
i
n
i
c
1
4
6
3
Villas
1
2
0
G
o
v
t
T
y
G
w
y
n
2
9
Depot Depot
12
61
P
a
lle
g
P
la
c
e
2
1
0
1
6
a
7
1
Ty Afal
E
l S
u
b
S
ta
P
a
th
(u
m
)
6
5
1
6
63
Heap
(dis)
Heap
(dis)
1
9
P
a
t
h
(
u
m
)
FB
Caeralem
Ty-Ni
Penlan-Fach
Coed
Nant-y-Mynydd
Maes y Dderwen
Y Wern
Primary School
P
ath (um
)
P
a
t
h
(
u
m
)
Heap
(dis)
Heap (dis)
Heap
(dis)
Ysgol Gymraeg Dyffryn Glowyr
Weir
Weir
Weirs
P
a
t
h
Mast (telecommunication)
The Nook
C
W
R
T
Y
G
L
O
C
H
Ty Gardd
4
S
C
H
O
O
L
R
O
A
D
H
E
O
L
Y
R
Y
S
G
O
L
/
G
L
A
N
T
W
R
C
H
CO
ED
LA
N
H
E
O
L
A
A
R
O
N
GLANNANT TERRACE
G
LA
NN
AN
T T
ER
RA
CE
P
E
N
Y
W
E
R
N
S
A
I
N
T
D
A
V
I
D
'
S
R
O
A
D
Ysgol Gymraeg Ystalyfera
1 to 35
Ystalyfera Rugby Club
M
aes-Y
-D
arren
6
2
5
6
1
1
0
57
5
1
7
80.1m
G
LAN
Y
R
A
FO
N
G
L
A
N
Y
R
A
F
O
N
G
L
A
N
Y
R
A
F
O
N
T
r
a
c
k
CG
P
a
th
(u
m
)
P
a
t
h
C
L
A
R
E
R
O
A
D
/
H
E
O
L
C
L
A
R
E
B
u
n
g
a
lo
w
ESS
3
3
T
C
B
31
26
11
5
1
3
2
4
Bank
5
3
3
3
5
2
5
0
2
6
1
4
H
is
to
n
3
7
4
2
67.4m
25
2
3
5
60.6m
3
6
S
h
e
l
t
e
r
2
9
61.2m
3
5
Play Area
Play Area
Play Area
PO
4
3
5
1
0
1
3
9
8
27
9
7
3
6
Filling Station
1
to
7
Cwrt
Gorof
S
h
e
l
t
e
r
S
h
e
l
t
e
r
Play Area
Apostolic
Church
S
h
e
lt
e
r
S
h
e
l
t
e
r
(Sch)
Shelter
Shelter
El Sub Sta
Ruin
S
h
e
l
t
e
r
Play Area
El Sub Sta
P
a
t
h
Bowling Green
B4599
B
4
5
9
9
Wern Fawr
4
1
H
E
O
L
G
L
A
N
R
H
Y
D
/
G
L
A
N
R
H
Y
D
R
O
A
D
El Sub Sta
Cricket Ground
Recreation Ground
C
O
M
M
E
R
C
I
A
L
S
T
R
E
E
T
/
S
T
R
Y
D
M
A
S
N
A
C
H
O
L
Z
O
A
R
R
O
A
D
/
H
E
O
L
Z
O
A
R
W
E
R
N
R
O
A
D
/
H
E
O
L
Y
W
E
R
N
C
L
A
R
E
R
O
A
D
/
G
O
U
G
H
R
O
A
D
/
H
E
O
L
G
O
U
G
H
Play Area
El Sub Sta
El Sub Sta
Cornerways
Lighting Tower
C
o
a
c
h
H
o
u
s
e
S
h
e
l
t
e
r
Tank
L
i
n
e
o
f
P
o
s
t
s
P
ath (um
)
Lighting Towers
Pavilion
ESS
ESS
Sports Ground
Maes-y-coed House
5
W
o
rks
W
o
r
k
s
Workshops
C
h
a
p
e
l
Ystradgynlais
P
a
t
h
(
u
m
)
Playing Field
H
E
O
L
C
L
A
R
E
T
ra
ck
53a
P
a
t
h
Pen-y-graig
(disused)
Sta
Burial Ground
T
r
a
c
k
T
r
a
c
k
T
r
a
c
k
T
r
a
c
k
PostsPosts
18
4
5
3
2
8
3
3
0
3
2
7
4
9
Cysgod
R
D
P
E
N
T
W
Y
N
Midland
Rivendell
GG
El Sub Sta
C
W
R
T
Y
G
A
M
L
A
S
Y
Mynydd
S
u
r
g
e
r
y
4
3
3
2
6
3
2
1
3
2
9
2
8
ESS
7
1
0
Woodlands Business Park
/ Parc Busnes Coed Cedwyn
4
Ppg Sta
(Sch)
I
n
d
u
s
t
r
ia
l
E
s
t
a
t
e
S
N
O
W
T
E
R
R
A
C
E
ESS
1
a
Ysgol Bro Tawe
L
i
g
h
t
i
n
g
T
o
w
e
r
s
Ysgol Maesydderwen
or Maesydderwen School
F
F
O
R
D
D
Y
R
A
F
O
N
Gardens
L
i
g
h
t
i
n
g
T
o
w
e
r
s
Path
El Sub Sta
2
T
e
n
n
i
s
C
o
u
r
t
C
o
m
m
u
n
i
t
y
C
e
n
t
r
e
1
6
1
6
5
3
78a
4
Filling Station
Tanks
6
G
O
R
O
F
R
O
A
D
75.3m
Golwg y Cwm
121.0m
Y
G
I
L
W
E
R
N
L
y
n
s
d
a
l
e
85
87
3
8
a
2
9
1
Golwg
Y
Darren
9
3
4
3
8
3
1
2
9
1
1
1
0
1
M
A
E
S
-Y
-C
O
E
D
9
126.8m
1
8
1
3
P
A
R
K
P
a
t
h
(
u
m
)
1
1
3
56.6m
Terrace
Chrisgar
Ystradgynlais
Community
Hospital
1
4
1
5
T
r
a
c
k
Picnic Area
Pavilion
Sewage Works
Path (um
)
Workings (dis)
Tank
Heap (dis)
Heap (dis)
Twrch
Bridge
Glan-rhyd
1
5
C
y
c
le
W
a
y
W
e
i
r
Cwm Wanderers
(Football Ground)
2
6
a
2
6
1
1
Ystradgynlais
Sports Centre
Shelters
D
i
s
m
a
n
t
l
e
d
R
a
i
l
w
a
y
L
a
y
-
b
y
Public Recycling Facility
(
P
H
)
81.2m
91.6m
86.6m
ETL
El Ps
E
T
L
E
T
L
E
T
L
P
ip
e
lin
e
El Ps
E
T
L
E
T
L
El Ps
ETL
E
T
L
Issues
Issues
Spring
D
r
a
i
n
D
r
a
i
n
Pond
Pond
Pond
Pond
Fe
ed
er (d
isu
se
d)
Issues
Waterfall
Issues
Issues
Pond
Issues
Issues
Spring
Pond
D
r
a
i
n
Drain
Pond
Issues
D
r
a
in
Issues
Issues
D
r
a
in
Spring
Spring
Issues
Issues
Issues
A
fo
n
T
w
rc
h
Pond
D
ra
in
Spring
Spring
Drain
D
ra
in
Spring
Pond
Pond
Spring
Pond
Pond
P
o
n
d
Issues
Spring
P
o
n
d
Drain
Pond
A
fo
n
T
w
r
c
h
Issues
D
r
a
i
n
A
f
o
n
T
w
r
c
h
Spring
Sinks
Issues
Pond
Sinks
Pond
Afon T
aw
e / R
iver T
aw
e
Pond
A
f
o
n
T
a
w
e
/
R
i
v
e
r
T
a
w
e
Afon Tawe / River Tawe
Ford
Spreads
Spreads
Ford
Ford
Spreads
Collects
Collects
Collects
Collects
Ford
Spreads
Collects
D
r
a
i
n
P
a
t
h
(
u
m
)
11
8
59.0m
G
L
A
N
Y
R
A
F
O
N
Row
Office
Swansea Valley Business Park
S
h
i
n
g
l
e
C
a
r
P
a
r
k
G
l
a
n
-
y
r
-
a
f
o
n
FENCE
FENCE
G
A
L
V
A
N
I
S
E
D
S
T
E
E
L
F
E
N
C
E
G
A
L
V
A
N
I
S
E
D
S
T
E
E
L
F
E
N
C
E
G
A
L
V
A
N
I
S
E
D
S
T
E
E
L
F
E
N
C
E
G
A
L
V
A
N
IS
E
D
S
T
E
E
L
F
E
N
C
E
GALVANISED STEEL
FENCE
INDUSTRIAL
BUILDING
CONCRETE
PAD
GRASS
GRASS
RE-LANDSCAPED
AREA
A
4
0
6
7
A
4
0
6
7
A
4
0
6
7
TARMAC
TARMAC
TARMAC
GRASS
TARMAC
SUB-BASE
SUB-BASE
CONCRETE
CONCRETE
TP
5
8
.
3
2
5
8
.
3
9
5
8
.
5
1
5
8
.
5
9
5
8
.
6
2
5
8
.
7
3
5
8
.
8
0
5
8
.
8
6
5
8
.
9
1
5
8
.
9
1
5
8
.
9
6
SLB
SLB
5
9
.
0
7
5
9
.
0
3
5
9
.
0
0
5
8
.
9
5
5
8
.
9
7
5
7
.
5
0
5
7
.
2
9
5
7
.
1
7
5
7
.
0
7
5
7
.
0
0
56.92
56
.87
5
6
.
8
8
5
6
.
8
9
5
6
.
8
9
5
6
.8
6
5
7
.
0
2
5
7
.0
1
5
6
.
9
7
5
7
.
0
3
5
7
.0
2
5
7
.
0
2
5
6
.
8
6
5
6
.
8
4
5
6
.
9
8
5
7
.0
4
5
7
.
0
2
5
7
.
0
3
5
7
.
0
0
5
7
.
0
2
5
6
.
8
7
5
6
.
9
3
5
6
.
9
0
5
6
.
9
0
5
6
.
8
7
5
6
.
8
8
5
6
.9
3
5
6
.9
4
5
6
.
9
1
5
6
.
9
3
5
6
.
9
5
5
6
.
9
5
5
6
.
8
7
5
6
.8
9
5
6
.
8
9
5
6
.
8
9
5
6
.8
5
5
6
.
8
4
5
6
.
8
5
5
6
.
8
5
Eaves Level
61.97
Eaves Level
62.70
Eaves Level
62.13
Ridge Level
64.39
Ridge Level
64.86
Ridge Level
64.38
Floor Level
57.08
Floor Level
57.09
Floor Level
57.06
5
6
.
9
0
5
6
.8
6
56.83 56.90
5
6
.
8
8
56.88
5
6
.
9
0
5
6
.
8
6
5
6
.
8
7
5
6
.
8
7
5
6
.
8
6
O
/
H
O/H
5
6
.
8
0
5
6
.
7
9
5
6
.
7
6
5
6
.
7
6
5
6
.
7
8
5
6
.
7
8
5
6
.
7
8
5
6
.8
1
5
6
.
8
4
5
6
.
8
6
5
6
.
8
9
5
6
.
9
0
5
6
.
8
8
56.83
5
6
.7
8
5
6
.
9
2
5
6
.
9
3
5
6
.
8
9
5
6
.8
0
5
6
.7
5
5
6
.
7
4
5
6
.
7
9
5
6
.
8
8
5
6
.
9
3
5
6
.
7
6
5
6
.
7
5
5
6
.
7
7
5
6
.
7
9
5
6
.
7
8
5
6
.
7
7
5
6
.
7
8
5
6
.
7
9
5
6
.
7
9
5
6
.
7
9
5
6
.
8
0
5
6
.
7
9
5
6
.
7
6
5
7
.
0
0
5
7
.0
0
5
6
.
9
5
5
6
.
7
8
5
6
.
8
0
5
6
.
7
7
5
6
.
7
8
5
6
.
7
7
5
6
.
7
8
5
6
.
7
8
5
6
.
8
8
5
7
.
2
5
5
6
.
7
5
57
.00
5
6
.8
4
5
6
.
8
4
5
6
.
9
5
56
.9
3
5
7
.
0
3
5
7
.
0
5
57
.0
2
56
.98
5
7
.
0
2
5
7
.
0
0
N
208167.867
D4
Z
59.171
E
276500.415
N
208199.071GPS1
Z
56.819
E
276467.129
N
208229.562
D5 Z
56.785
E
276422.660
N
208267.110
D2
Z
56.922
E
276515.090
N
208231.154
D3
Z
58.530
E
276552.026
SV
SV
SV
SV
SV
RS
RS
RS
RS
RS
RS
58.74
58.73
59.16
59.09
58.97
58.78
59.12
58.25
58.02
58.54
58.49
58.65
58.88
58.64
58.65
58.80
58.87
59.15
57.40
57.41
57.50
57.89
58.04
58.05
57.89
57.81
58.54
56.81
56.77
56.88
56.85
56.90
56.87
56.96
56.93
57.04
57.41
57.54
57.62
57.73
57.63
57.60
57.61
56.84
56.86
56.85
56.91
56.95
56.90
56.89
56.95
56.85
58.02
58.11
58.09
58.00
58.06
58.06
56.84
56.87
56.91
56.91
56.81
56.84
56.79
56.79
56.80
56.79
56.81
56.83
57.89
58.16
57.94
58.00
58.36
58.43
58.39
58.42
58.61
58.46
58.44
58.41
58.33
58.01
57.84
58.33
58.52
58.55
58.59
56.95
57.44
57.36
57.25
57.08
57.05
56.86
56.88
56.84
56.77
56.82
56.86
56.89
57.39
57.42
58.75
58.67
58.52
58.35
58.04
57.89
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
BT
BT
BT
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
MH
CL
59.12
CL
58.71
CL
56.82
CL
56.95
CL
57.00
CL
56.93
CL
56.83
CL
56.89
CL
57.00
CL
56.90
CL
56.94
CL
56.98
CL
56.91
CL
56.92
CL
56.86
CL
56.86
CL
56.82
CL
56.80
LP
LP
LP
5
6
.
8
8
5
6
.
9
2
5
6
.
9
4
5
6
.9
1
5
6
.
9
1
5
6
.
9
6
5
6
.
8
8
5
6
.
8
8
5
6
.
8
2
56
.8
4
5
6
.
8
8
5
6
.
8
8
5
6
.
8
6
5
6
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9
1
5
6
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8
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9
0
5
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8
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3
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5
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3
6
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4
5
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5
1
5
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5
2
5
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6
5
5
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6
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5
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7
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5
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8
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5
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1
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0
1
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0
9
5
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0
9
5
9
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1
1
5
9
.
1
4
5
9
.
2
1
5
9
.
2
4
5
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9
5
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2
5
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.
5
6
5
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5
6
5
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.
5
9
5
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.
6
1
5
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.
5
9
5
7
.
5
0
5
7
.
0
9
57.71
57.76
57.83
5
8
.
0
2
5
8
.1
9
57.68
57.70
57.67
57.68
5
7
.
1
0
5
7
.
1
5
5
7
.
0
9
56
.88
56.81
5
6
.
8
6
56.95
5
7
.
0
4
5
7
.
1
3
5
7
.
0
3
5
6
.
9
8
5
6
.
9
3
5
6
.
8
6
56.82
5
6
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9
5
6
.
7
2
58.14
5
8
.
2
1
58.16
5
9
.
2
4
5
9
.
1
6
5
9
.
0
4
5
9
.
0
0
5
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0
2
5
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.
9
7
5
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8
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5
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.
6
5
5
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.
5
2
5
8
.
3
6
5
8
.
1
6
57.81
57.68
57.71
57.73
5
7
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2
5
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6
5
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.
4
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5
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.
5
4
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1
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5
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1
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4
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5
5
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2
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5
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3
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9
5
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3
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3
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1
5
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8
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5
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9
2
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9
2
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9
2
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5
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1
3
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8
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5
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0
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9
4
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1
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5
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9
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5
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0
2
5
7
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0
1
5
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0
6
56.77
56.82
56.8256.7956.80
56.85
5
8
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3
5
5
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4
7
5
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4
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7
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2
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3
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5
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5
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5
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5
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5
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3
5
56.92
5
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.
9
2
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0
6
5
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.
2
8
5
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.
2
8
5
7
.
3
6
5
7
.
3
1
57.31
5
7
.
3
3
5
7
.
5
1
5
7
.
3
7
5
7
.
4
6
5
7
.
2
5
5
8
.
9
8
5
9
.
0
0
56
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56.91
56.87
5
6
.
9
2
5
6
.
9
2
5
6
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8
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5
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.
8
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56
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5
6
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2
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56
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56.79
5
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1
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3
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56.76
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56.84
56.95
57.02
56.85
56.84
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Client:
Project:
Drg Title:
Date:
Drg No.
tuliptulip
engineering consultancy
FLOOD ZONE
PLAN
09.04.2020
Status:
PLANNING
J009/002 Rev.
SWANSEA VALLEY
IND. EST. FCA
CB3 CONSULT LTD
Scale:1:10,000
-
Size:A3
Rev Date
34 Culfor Road, Loughor, Swansea SA4 6TY
tel: 01792 893407 mob: 07843 491524
w: www.tulipengineering.co.uk
Ceir rhestr lawn o delerau ac amondau yn https://naturalresources.wales/rhybuddsafonol neu drwy gysylltu ag [email protected]. A full list of terms and condiitions is available from the https://naturalresources.wales/StandardNotice or by contacting [email protected] © Crown copyright and database rights 2017 Ordnance Survey 100019741. Geological Mapping: British Geological Survey ©NERC. Centre for Ecology & Hydrology © NERC (CEH). Defra and Met Office © Crown copyright. © Cranfield University. © James Hutton Institute. Land & Property Services © Crown copyright and database right.
1:
12/04/2020
Dyddiad / Date
Map Title
5,001
Map Perygl Llifogydd / Flood Risk Map
Graddfa / Scale
0.13
Kilometers
0.3
British_National_Grid
00.3
Allwedd / Map KeyHigh Surface Water Flood Risk - Extent
Medium Surface Water Flood Risk - Extent
Low Surface Water Flood Risk - Extent
Swansea Valley Business Park, Ystalafera Project Number: J009 Document Reference: FCA/01
https://d.docs.live.net/9692ee99776ac28f/Documents/Tulip Engineering Consultancy/Jobs/J009 - Swansea Valley Ind Est FCA/Production/Data - Internal/FCA - Swansea Valley Ind Est.docx
D. Hydraulic Modelling Technical Note
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 1 of 9
1 Introduction
1.1 Terms of reference
JBA Consulting have been commissioned by P & C James to undertake hydraulic
modelling of the Afon Twrch and Afon Tawe to support a proposed new development at
Swansea Valley Business Park in Glanyafon, Ystalyfera in West Wales. The hydraulic
modelling required the updating the existing modelling in the study area as well as
updating the hydrological estimates applied to this model.
1.2 Study area
The proposed development site is located on Glan Yr Avon road in Glanyafon. The Afon
Tawe flows approximately 50m to the south-east of the proposed development from
north to south. The Afon Twrch is located approximately 685m to the north-east of the
proposed development. The Ordnance Survey (OS) National Grid Reference for the site
is SN 76966 09006.
1.3 Proposed development and planning policy
The proposed development is for industrial units on brownfield land. Industrial
development is classified in Technical Advice Note (TAN) 15 as 'less vulnerable'
development (Welsh Assembly Government, 2004).
The proposed development site is currently within Natural Resources Wales
(NRW)Development Advice Map (DAM) Zone C2, defined as areas at risk of flooding
'without significant flood defence infrastructure' (Welsh Assembly Government, 2004).
The NRW Flood Map is informed by the results of the 2016 Ysgol Gyfun Ystalyfera Flood
Consequence Assessment (FCA) 1D-2D model. This model was developed by JBA
Consulting as part of an FCA for a school building at the Ysgol Gyfun Ystalyfera Primary
School. The 2016 model is largely based on a 2013 Cwm Twrch 1D-2D Flood Hazard
Modelling model, also developed by JBA Consulting on behalf of Natural Resources Wales
(NRW). The main changes undertaken in 2016, were to include the latest LIDAR, update
the representation of the footbridge between Glan Yr Avon and Glanwrch as well as to
update the hydrological inflow for the Afon Twrch.
NRW’s DAM showing of the proposed development location is shown in Figure 1-1.
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 2 of 9
Figure 1-1: NRW’s DAM showing the proposed development site location (proposed
development site in red)
Afon Tawe
Afon Twrch
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 3 of 9
2 Flood risk assessment
2.1 Hydraulic model
The 2016 Ysgol Gyfun Ystalyfera Flood Consequence Assessment 1D-2D model was
updated to assess the flood risk at the Swansea Valley Business Park site.
2.2 Hydrology
The hydrology calculated in 2016 is now outdated due to developments in hydrology
methods, guidance and data availability. Therefore, new hydrological inflows were
generated for both the Afon Tawe and Afon Twrch. The updated flows have been
developed using the Flood Estimation Handbook (FEH) Statistical method as QMED was
has been improved by using local donors. Full details of the method used to generate
the peak flows can be found in the flood estimation report, in Appendix A. Peak flows
derived for this study are provided in Table 2-1.
Table 2-1: Estimated peak flows
The updated hydrology was incorporated within the model as shown in Figure 2-1.
Within the 2016 modelling, the intervening area hydrograph between Taw_01 and
Taw_02 was applied as two point inflows. This method has been updated so that the
inflow is spread equally across all model nodes on the Afon Tawe. This method has been
selected as an inspection of aerial imagery, mapping and LIDAR data shows that there
are a large number of small drains on the left bank of the Afon Tawe that drain into the
channel throughout the reach represented in the model.
Site code
Flood peak (m3/s) for the following AEP (%) events
50 1 0.1
TWR_01 66 157 248.8
TAW_01 169 369 576.8
TAW_02 115 252 393.3
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 4 of 9
Figure 2-1: Inflows applied to updated model
2.3 1D model updates
The following updates have been made to the 2016 model to ensure that it is in line with
current modelling best practice:
• All bridge 'B' channel types have been changed to the newer 'BB' channel type, which
automatically calculates losses. Form Loss Values for these structures have been
updated to 0.001, unless piers are present at the structures.
• All weir 'W' channel types have been changed to the newer 'WW' channel type. Each
structure has been reviewed and an appropriate Cd value selected.
2.4 TUFLOW version
The updated model was simulated with the new hydrology using TUFLOW version
2018-03-AE-iSP-w64.
2.5 Model Scenarios
Simulations were completed for the 1% Annual Exceedance Probability (AEP) event
with an allowance for climate change (plus 30% (Welsh Government, 2016) and 0.1%
AEP event. The modelling files are shown in Table 2-2.
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 5 of 9
Table 2-2 Hydraulic modelling files
Run
Reference
TWRC_077_Q0100CC_8.5hr
TWRC_077_Q1000_8.5hr
Purpose of
Runs:
The purpose of this model scenario was to understand the
baseline flood risk to the proposed development.
ISIS/TUFLOW file
and Version:
File names:
TWRC_077_~e1~_8.5hr.tcf TAWE_007.tbc
TWRC_003_A.tbc
TWRC_077.ecf Materials_NWPT.tmf
bc_dbase_CWMTWRCH_076.csv CWMTWRCH_076.trd
TAWE_076.tgc
TWRC_008.tgc
Model Timesteps: 1D model timestep: 1s
2D model timestep: 2s
Run Time: Model run time: 20 hours
Maximum simulation time: 1:01 hours
Return period(s): 1% AEP with an allowance for climate change (+30%).
0.1% AEP.
Run
Settings:
Multi-domain model.
Defended model.
Comments on
results:
Negative depth warnings: 0
Maximum cumulative ME: 0.50%
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 6 of 9
3 Modelling Results
3.1 Mapped Results
3.1.1 Updated 1% AEP plus Climate Change (30%)
Results from the updated modelling show that the proposed development site does not
flood during the 1% AEP plus climate change event. The maximum depths for this
modelled event are shown in Figure 3-1.
Figure 3-1: 1% AEP plus climate change maximum flood depth
3.1.2 Baseline 0.1% AEP event
Results from the updated modelling show that proposed development site does not flood
during the 0.1% AEWP event. Out of bank flooding occurs on the right bank of the Afon
Twrch at Ysgol Gyfun Ystalyfera, which flows south before ponding around Varteg Road,
approximately 160m to the east of the proposed development. The maximum depths for
this modelled event are shown in Figure 3-2.
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 7 of 9
Figure 3-2: Baseline 0.1% AEP event maximum flood depth
3.2 Model performance
• The model ran stably for all events. The model simulation time was approximately 1
hour.
• Peak mass error was 0.50% which occurred during the 0.1% AEP event. This is within
the acceptable limit of +/-1%.
• No negative depths occurred in either the 1D or 2D domain for any of the model
simulations undertaken as part of this study.
• A total of 36 check and warning messages were generated during the simulation.
None of them are messages that didn't occur during the original modelling.
3.3 Modelling assumptions and limitations
• No further updates have been made to the 2016 model, other than those detailed in
Section 2.
• The hydraulic modelling does not represent flooding from; surface water,
groundwater or sewers.
Out of bank flooding on the
right bank of the Afon Twrch
Ponding at Varteg Road
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 8 of 9
4 Conclusions and recommendations
• JBA Consulting were commissioned by P & C James to undertake hydraulic modelling
to inform an FCA for a proposed development site at Swansea Valley Business Park,
Ystalyfera.
• The Ysgol Gyfun Ystalyfera FCA model, developed in 2016 by JBA Consulting was
updated as part of this study. The 1D structure model representation and inflow
hydrology was updated to comply with the latest methods and guidance.
• The updated model was simulated using the latest software version to generate flood
risk mapping for the 1% AEP event with an allowance for climate change and the
0.1% AEP events.
• Results from the updated modelling show that the proposed development floods in
neither the 1% AEP plus climate change event nor the 0.1% AEP event.
5 Bibliography
Welsh Assembly Government. (2004). Technical Advice Note 15: Development and Flood Risk. Welsh Government. (2016). Flood Consequence Assessments: Climate change allowances.
TECHNICAL NOTE
JBA Project Code 2019s0932
Contract Swansea Valley Modelling
Client CB3 Consult Ltd
Day, Date and Time 4th September 2019
Author Adam Sinclair Reviewer Amy Evans Subject Hydraulic modelling report
www.jbagroup.co.uk
www.jbaconsulting.com www.jbarisk.com
Page 9 of 9
Appendix A: FEH calculation record
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 1
Flood estimation report: Afon
Twrch & Afon Tawe, Swansea
Introduction
This report template is based on a supporting document to the Environment
Agency’s flood estimation guidelines. It provides a record of the hydrological
context, the method statement, the calculations and decisions made during flood
estimation and the results.
Contents
1 Method statement 3
2 Locations where flood estimates required 8
3 Statistical method 10
4 Revitalised flood hydrograph 2 (ReFH2) method 14
5 Discussion and summary of results 16
6 Annex 19
Approval
Name and qualifications Date
Method statement prepared
by:
Kate Drewett BSc MSc
02/08/2019
Method statement reviewed
by:
Jenni Essex BSc MSc PhD CEnv
MCIWEM C.WEM
12/08/2019
Calculations prepared by: Kate Drewett BSc MSc
02/08/2019
Calculations reviewed by: Jenni Essex BSc MSc PhD CEnv
MCIWEM C.WEM
12/08/2019
Revision History
Revision
reference
Date issued Amendments Issued to
V1.0 14/08/2019 - CB3 Consult
Ltd
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 2
Abbreviations
AEP ......................... Annual Exceedance Probability
AM ........................... Annual Maximum
AREA ....................... Catchment area (km2)
BFI .......................... Base Flow Index
BFIHOST .................. Base Flow Index derived using the HOST soil classification
CFMP ....................... Catchment Flood Management Plan
CPRE ....................... Council for the Protection of Rural England
FARL ........................ FEH index of flood attenuation due to reservoirs and lakes
FEH ......................... Flood Estimation Handbook
FSR ......................... Flood Studies Report
HOST ....................... Hydrology of Soil Types
NRA ......................... Natural Resources Wales
NRFA ....................... National River Flow Archive
OS ........................... Ordnance Survey
POT ......................... Peaks Over a Threshold
QMED ...................... Median Annual Flood (with return period 2 years)
ReFH........................ Revitalised Flood Hydrograph method
SAAR ....................... Standard Average Annual Rainfall (mm)
SPR ......................... Standard percentage runoff
SPRHOST ................. Standard percentage runoff derived using the HOST soil
classification
Tp(0) ....................... Time to peak of the instantaneous unit hydrograph
URBAN ..................... Flood Studies Report index of fractional urban extent
URBEXT1990 ............ FEH index of fractional urban extent
URBEXT2000 ............ Revised index of urban extent, measured differently from
URBEXT1990
WINFAP-FEH ............. Windows Frequency Analysis Package – used for FEH statistical
method
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 3
1 Method statement
1.1 Requirements for flood estimates
Overview The purpose of the study is to update an existing 1D-2D model of the
Afon Tawe and Afon Twrch at Ystalyfera, South Wales, determine the
flood risk for a development site at Swansea Valley Business Park
(approximate NGR 276499, 208214). This requires a new hydrological
assessment for the location of interest to ensure that the most
appropriate flood flow estimates are used in the model, using the latest
methods, data and software.
Design peak flow estimates and hydrographs are required for the
purposes of the hydraulic modelling and will be generated for a range of
annual exceedance probability (AEP) events. However, for the purposes
of this study, only the 1% and 0.1% AEP events are required to be
modelled.
The effects of climate change will be accounted for using the latest
guidance1. An uplift of 30% will be made to the 1% AEP flow estimates,
based on the location of the catchment within the Western Wales district.
Project scope The study is being undertaken for a small development application; the
project scope reflects this purpose. There is a limited amount of time
available for the hydrological assessment, which constrains the
complexity to a routine assessment:
• Brief Internet search only for information on historical flooding.
• No rating reviews or flood event analysis for local gauges.
• No consideration of fluvial-fluvial joint probability of flooding from the
Afon Tawe and Afon Twrch.
• Previous hydrological analysis will be assessed to identify if this can
be made use of within the current study.
1 Welsh Government (2016) CL-03-16 Guidance for Flood Consequence Assessments – Climate Change Allowances. Available at: https://gweddill.gov.wales/docs/desh/publications/160831guidance-for-flood-consequence-assessments-climate-change-allowances-en.pdf
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 4
1.2 The catchment
Figure 1-1 Catchment overview & location of flow estimation points
Figure 1-2 Site location
Afon Twrch
Afon Tawe
Contains Ordnance Survey data Crown © Copyright and Database Right 2019
Contains Ordnance Survey data Crown © Copyright and Database Right 2019
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 5
Description
The Afon Tawe rises in the Brecon Beacons near Moel Feity. It flows in a south-
westerly direction to Swansea, where it discharges into the Bristol Channel. The
topography is steep throughout the catchment. The main tributaries are the
River Twrch which joins the Tawe at Ystalyfera, the Cwm Du at Ynsmeudwy, the
Upper Clydach River at Pontardawe and Cwm Clydach joins the Tawe
downstream at Clydach.
The Afon Tawe has a catchment area of approximately 924m2 just upstream of
the confluence with the Twrch.
The Afon Twrch rises in the Black Mountains near Llyn y Fan Fach and flows in
a southerly direction to the Afon Tawe at Ystalyfera. The main tributaries are
the Nant Gyws and the Afon Llynfell. The Afon Twrch catchment is
approximately 50km2 at the confluence with the Tawe.
Both catchments are essentially rural with most urbanisation concentrated in
the lower catchment and along the watercourses. The main settlements within
the Twrch catchment are Cwmllynfell, Cwm-twrch Uchaf, Cwm-twrch Isaf and
Gurnos before the Twrch joins the Tawe at Ystalyfera. There are former
opencast mine workings in the lower catchment and some forested areas.
The British Geological Survey website2 1:50,000 scale mapping shows the
catchment to be underlain by the following:
• Upper catchment:
o Upper and Lower Devonian Rocks (undifferentiated) – sandstone
and conglomerate, interbedded
o Dinantian Rocks (undifferentiated) – limestone with subordinate
sandstone and argillaceous rocks, with some superficial deposits
of till
o Millstone Grit Group – mudstone, siltstone and sandstone, with
some superficial deposits of till
• Lower catchment:
o Pennine and South Wales Lower and Middle Coal Measures
Formations – mudstone, siltstone, sandstone, coal, ironstone
and ferricrete, with some superficial deposits of till
o South Wales Upper Coal Measures Formation – mudstone,
siltstone, sandstone, coal, ironstone and ferricrete.
Soils in the upper catchment are mostly described as slowly permeable, wet,
very acid upland soils. Downstream of Ystradgynlais, soils are more mixed
including some areas of freely draining acid loamy soils3.
The catchment response to rainfall is likely to be rapid due to the steep
topography and reasonably impermeable geology and soils. The historical
mining operations may have changed the natural runoff response of the
catchment. It is difficult to determine the exact consequences of this, certainly
not without a detailed investigation of available data; this assessment is not
within the scope of the study.
1.3 Source of flood peak data
Source
NRFA peak flows dataset, Version 7, released October 2018. This contains data
up to water year 2016-17.
2 http://mapapps.bgs.ac.uk/geologyofbritain/home.html 3 http://landis.org.uk/sooilscapes/index.cfm
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 6
1.4 Gauging stations (flow or level)
Water-
course
Station
name
NRFA
number
Catchment
area (km²)
Type
(rated /
ultrasonic
/ level…)
Start of record and
end if station closed
Twrch Gurnos Unknown 49.9 Level N/A
1.5 Other data available and how it has been obtained
Type of data Data
relevant
to this
study?
Data
available
?
Source of
data
Details
Check flow gaugings
No N/A N/A N/A
Historic flood data Yes Yes Various An internet search found
reports of landslips and
surface water flooding in
2012 and 2016. A flood
investigation report4 revealed
surface water and river
flooding on 3rd September
2016 caused internal flooding
to a number of properties on
Gough Road in Ystalyfera.
Flow or river level data
for events
No N/A N/A N/A
Rainfall data for
events
No N/A N/A N/A
Potential evaporation
data No N/A N/A N/A
Results from previous
studies
Yes Yes JBA
Consulting
JBA Consulting. April 2013.
Cwm Twrch 1D-2D Flood
Hazard Modelling.
JBA Consulting. November
2016. Ysgol Gyfun Ystalyfera
FCA.
Other data or
information
No N/A N/A N/A
1.6 Hydrological understanding of catchment
Conceptual model The main site of interest is the proposed development site on the right
bank of the River Tawe, downstream of the confluence of the Twrch
and Tawe.
Peak flows in the Afon Twrch and Tawe exceeding the channel capacity
is the most likely cause of flooding to the site. There is a road bridge
and footbridge across the Afon Tawe adjacent to the site; these do not
4 Neath Port Talbot Council, 2017. Investigation Report into Flooding Incident of 3rd September 2016 Gough Road, Ystalyfera.
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 7
appear to be a significant constriction to flow.
Unusual catchment
features
There are former opencast mine workings within the catchments. It is
not known how these will affect runoff response from the catchment
and they have not been specifically considered within this assessment
(not within scope).
1.7 Initial choice of approach
Is FEH appropriate? Yes
Initial choice of method(s)
and reasons
How will hydrograph shapes
be derived if needed?
Will the catchment be split
into sub-catchments? If so,
how?
Both FEH Statistical and ReFH2 methods are suitable for flood
flow estimation for the Afon Twrch and Tawe catchments. The
catchments are not large, permeable or urbanised.
The FEH Statistical and ReFH2 methods will both be applied,
and the results compared as there no clear reason to prefer
one method over the other at this stage.
Hydrograph shapes will be derived using the ReFH2 model.
If the FEH Statistical method generates the preferred design
peak flow estimates, the ReFH2 hydrographs will be fitted to
the Statistical peaks.
Intervening area catchment descriptors will be derived for the
area between lumped catchment flow estimation points.
Lateral inflows will be applied to the model across this reach,
if required.
Software to be used (with
version numbers)
FEH Web Service5/ WINFAP v3.0.0036 / ReFH2.2
5 CEH 2015. The Flood Estimation Handbook (FEH) Online Service, Centre for Ecology & Hydrology, Wallingford, Oxon, UK. 6 WINFAP-FEH v3 © Wallingford HydroSolutions Limited and NERC (CEH) 2009.
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 8
2 Locations where flood estimates required
The table below lists the locations of subject sites. The site codes listed below are used in
all subsequent tables to save space.
2.1 Summary of subject sites
Site
code
Type of
estimate
L: lumped catchment
S: Sub-catchment
Watercourse Name or
description
of site
Easting Northing AREA
on FEH
CD-
ROM
(km2)
Revised
AREA if
altered
TWR_01 L Afon Twrch Afon Twrch
catchment at
confluence
with Afon
Tawe
277100 208450 50.7 -
TAW_01 L Afon Tawe Afon Tawe at
Godre’r-
graig
(downstream
model
extent)
275450 206550 150.6 -
TAW_02 L Afon Tawe Afon Tawe
upstream of
Glan-rhyd
Bridge
(upstream
model
extent)
278350 209000 91.8 -
TAW_01
_IA S Afon Tawe Intervening
area
between
TAW_02,
TWR_01 and
TAW_01
- - - 8.1
Note: Lumped catchments (L) are complete catchments draining to points at which design flows are required.
Sub-catchments (S) are catchments or intervening areas that are being used as inputs to a semi-distributed model of the river system. There is no need to report any design flows for sub-catchments, as they are not relevant: the relevant result is the hydrograph that the sub-catchment is expected to contribute to a design flood event at a point further downstream in the river system. This will be recorded within the hydraulic model output files. However, catchment descriptors and ReFH model parameters should be recorded for sub-catchments so that the results can be reproduced.
The schematic diagram illustrates the distinction between lumped and sub-catchment estimates.
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 9
2.2 Important catchment descriptors at each subject site
(incorporating any changes made)
Red text indicates changes made to FEH catchment descriptors. URBEXT2000 has been updated to the current year (2019).
Site code
FARL PROPWET BFIHOST DPLBAR
(km) DPSBAR (m/km)
SAAR (mm)
URBEXT 20007
FPEXT
TWR_01 0.995 0.62 0.377 10.14 124.1 1987 0.016 0.035
TAW_01 0.994 0.62 0.373 14.84 141.6 2024 0.018 0.042
TAW_02 0.993 0.62 0.358 12.59 146.8 2071 0.014 0.039
TAW_01
_IA - 0.62 0.518 3.15 192.1 1724 0.076 -
2.3 Checking catchment descriptors
Record how catchment
boundary was checked
and describe any
changes
The catchment boundaries exported from the FEH Web Service were
compared to Ordnance Survey (OS) contour mapping8, spot
heights9 and 2m LiDAR data. The catchment boundaries from the
FEH Web Service appear reasonable and correlate with the mapping
for the upstream catchment to the study site.
Some minor discrepancies were found between the FEH catchment
boundaries and the contours, spot heights and watercourse lines.
One noted difference was with the TWR_01 catchment boundary in
the south-western corner. It was decided to retain the FEH
catchment area which is the larger value and will therefore be more
conservative, as done in the 2016 study.
Record how other
catchment descriptors
were checked and
describe any changes.
A qualitative check of the FEH Web Service BFIHOST values was
undertaken by comparing it to the geology and soils detailed in
Section Error! Reference source not found.. The BFIHOST value
is consistent with the geology and soils shown to underlie the
catchments.
The FARL values for all flow estimation points are supported by OS
mapping which shows only small online ponds on the rivers.
A qualitative check of the URBEXT2000 values were made by
comparing the FEH Web service values to current OS mapping. The
value is as would be expected for an essentially rural catchment
with a small amount of urbanisation in the lower extent. No changes
were made except to update URBEXT2000 to the current year (2019).
Source of URBEXT URBEXT2000
Method for updating of
URBEXT
CPRE formula from 2006 CEH report on URBEXT2000
7 URBEXT 2000 updated to 2019 8 OS Open Data. Terrain50_Contours 9 OS Open Data. Terrain50_SpotHeights
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 10
3 Statistical method
3.1 Overview of estimation of QMED at each subject site
Site
code
Initial QMED rural
(m3/s) (from
catchment descriptors) F
inal
meth
od
Data transfer
Urban adjust-
ment factor
(UAF)
Final QMED
estimate (m3/s)
NRFA numbers
for donor sites used
(see 3.3)
Distance between centroids dij (km)
Moderated QMED
adjustment factor, (A/B)a
If more than one
donor
Weig
ht
Weig
hte
d a
ve.
ad
justm
en
t
TWR_01 58 DT 58008
59001
9.54
3.45
1.07
1.18
0.5
0.5
1.12 1.116 65.7
TAW_01 150 DT 58008
59001
8.76
4.61
1.08
1.16
0.5
0.5
1.11 1.108 168.9
TAW_02 104 DT 58008
59001
9.72
6.85
1.07
1.14
0.5
0.5
1.10 1.098 115.2
Are the values of QMED spatially consistent? Yes, TAW_01 is the most downstream
and has the greatest QMED. The sum of
the upstream flows is greater than the
downstream flow, which is as would be
expected.
Method used for urban adjustment for subject and
donor sites
WINFAP v410
Parameters used for WINFAP v4 urban adjustment if applicable
Impervious fraction for
built-up areas, IF
Percentage runoff for
impervious surfaces,
PRimp
Method for calculating fractional urban
cover, URBAN
0.3 70% From updated URBEXT2000
Notes
Methods: AM – Annual maxima; POT – Peaks over threshold; DT – Data transfer (with urban adjustment); CD – Catchment descriptors alone (with urban adjustment); BCW – Catchment descriptors and bankfull channel width (add details); LF – Low flow statistics (add details).
The QMED adjustment factor A/B for each donor site is given in Table 3.2. This is moderated using the power term, a, which is a function of the distance between the centroids of the subject catchment and the donor catchment. The final
estimate of QMED is: (A/B)a x QMEDinitial x UAF
Important note on urban adjustment
The method used to adjust QMED for urbanisation published in Kjeldsen (2010)11 in which PRUAF is calculated from BFIHOST is not correctly applied in WINFAP-FEH v3.0.003. Significant differences occur only on urban catchments that are highly permeable.
10 Wallingford HydroSolutions (2016). WINFAP 4 Urban adjustment procedures. 11 Kjeldsen, T. R. (2010). Modelling the impact of urbanization on flood frequency relationships in the UK. Hydrol. Res. 41. 391-405.
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 11
3.2 Search for donor sites for QMED (if applicable)
Comment
on potential
donor sites
Hydrology estimations were carried out in 2016 by JBA for the Afon Twrch. The
two donor sites used in the 2016 study have been retained for the current study.
Potential donor sites were investigated using the function within WINFAP
coupled with the National River Flow Archive (NRFA) website to search for
nearby gauges. Their catchment descriptor derived QMED value was compared
with their observed QMED value to determine the magnitude of the adjustment
factor.
Six stations were considered in detail as donors for the TAW_01 and TAW_02
catchments:
• 58002 – Neath at Resolven
• 58006 – Mellte at Pontneddfechan
• 58008 – Dulais at Cilfrew
• 59001 – Tawe at Ynystanglws
• 59002 – Loughor at Tir-y-dail
• 60009 – Sawdde at Felin-y-cwm
60009 and 59002 were rejected as the SAAR value was significantly lower than
the study catchments and they had the highest QMED adjustment factors.
59001 is on the Afon Tawe but located several kilometres downstream of the
study site; catchment centroids for the study catchments are the closest to this
gauge. It also has similar FARL (0.996) and BFIHOST (0.407) values, however
the SAAR value (1890mm) is lower than the study catchments.
58008 has similar FARL (0.999), BFIHOST (0.377) and URBEXT (0.0181)
values, but also has a lower SAAR value (1806mm) than the study catchments.
58002 and 58006 have the most similar SAAR values to the study catchments,
however they have lower FARL values (0.983 and 0.975 respectively), indicating
a greater attenuation to lakes and reservoirs.
58008 and 58006 have the lowest QMED adjustment factors.
58008 and 59001 are the two closest gauges to TAW_01. 58002 and 59001 are
the two closest gauges to TAW_02.
It was decided than an equal weighting of 59001 and 58008 was most
appropriate for both TAW_01 and TAW_02 catchments to adjust QMED. This is
consistent with the approach used for TWR_01.
3.3 Donor sites chosen and QMED adjustment factors
NRFA
no.
Reasons for choosing Method
(AM or
POT)
Adjust-
ment for
climatic
variation
?
QMED
from
flow
data
(A)
QMED
from
catchment
descriptor
s (B)
Adjust
-ment
ratio
(A/B)
58008 See Section 3.2 AM No 56.5 46.9 1.20
59001 See Section 3.2 AM No 253 185 1.37
3.4 Derivation of pooling groups
In order to avoid discontinuities in flow estimates along watercourses it is useful to use as
few pooling groups as possible and to identify if one pooling group can be used to represent
several flow estimation points. Default pooling groups were generated for the three locations
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 12
and compared. All three pooling groups had quite different station composition and it was
decided to use a separate pooling group for each location in this case.
Name
of
group
Site code
from
whose
descriptor
s group
was
derived
Subject
site
treated as
gauged?
Changes made to default pooling
group, with reasons Weighted
average L-
moments
TWR_01 TWR_01 No No changes made L-CV =
0.187
L-Skew =
0.196
TAW_01 TAW_01 No No changes made L-CV =
0.169
L-Skew =
0.174
TAW_02 TAW_02 No No changes made L-CV =
0.172
L-Skew =
0.168
Note: Pooling groups were derived using the procedures from Science Report SC050050 (2008).
3.5 Derivation of flood growth curves at subject sites
Site
code
Metho
d
If P, ESS
or J,
name of
pooling
group
(Error!
Reference
source not
found.)
Distribution
used and
reason for
choice
Note any
urban
adjustment
or
permeable
adjustment
Parameters of
distribution
Growth
factor for
100-year
return
period
TWR_
01
P TWR_01 GL –
distribution that
provides best
fit.
v3 urban
adjustment
applied
Permeable
adjustment
not applied
as most sites
in the
pooling
group have
SPRHOST
>20%
Location: 1.000
Scale: 0.184
Shape: -0.199
2.38
TAW_
01
P TAW_01 GL –
distribution that
provides best
fit.
Location: 1.000
Scale: 0.167
Shape: -0.177
2.18
TAW_
02
P TAW_02 GL –
distribution that
provides best
fit.
Location: 1.000
Scale: 0.171
Shape: -0.170
2.19
Notes
Methods: SS – Single site; P – Pooled; ESS – Enhanced single site; J – Joint analysis
A pooling group (or ESS analysis) derived at one gauge can be applied to estimate growth curves at a number of ungauged sites. Each site may have a different urban adjustment, and therefore different growth curve parameters.
Urban adjustments are all carried out using the method of Kjeldsen (2010).
Growth curves were derived using the procedures from Science Report SC050050 (2008).
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 13
3.6 Flood estimates from the statistical method
Site
code
Flood peak (m3/s) for the following AEP (%) events
50 20 10 5 3.33 2 1.33 1 0.5 0.2 0.1
TWR_01 66 85 99 114 124 137 148 157 179 214 245
TAW_01 169 213 245 278 299 327 351 369 416 488 550
TAW_02 115 146 168 190 205 224 240 252 284 332 374
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 14
4 Revitalised flood hydrograph 2 (ReFH2) method
4.1 Catchment sub-divisions for ReFH2 model
Site code Area (km2)
Rural or un-
developed
Paved Only relevant if significant transfers of water
via sewers crossing catchment boundaries…
Paved with
sewers draining
out of
topographic
catchment
Paved outside
topographic
catchment with
sewers draining into
catchment
TWR_01 49.44 1.27 N/A N/A
TAW_01 146.38 4.25 N/A N/A
TAW_02 89.79 2.01 N/A N/A
Sources of
information
for creating
sub-divisions
N/A
Sewer capacity (return period / rainfall intensity / flow rate)
and source of information
N/A
4.2 Parameters for ReFH2 model
Site
code
Method
Tprural
(hours)
Tpurban
(hours)
Cmax
(mm)
PRimp
% runoff for impermeable
surfaces
BL
(hours)
BR
TWR_01 CD 2.70 1.35 261.46 70 35.45 1.12
TAW_01 CD 3.21 1.61 258.75 70 38.28 1.11
TAW_02 CD 2.89 1.45 248.87 70 36.02 1.06
Brief description of any flood event analysis carried out N/A
Methods: OPT: Optimisation, BR: Baseflow recession fitting, CD: Catchment descriptors, DT: Data transfer (give details)
4.3 Design events for ReFH2 method
Site
code
Season
of
design
event
Storm
duration
(hours)
Storm
area for
ARF
(if not
catchment
area)
Source of design rainfall statistics
(FEH99 or FEH13)
TWR_01 Winter 8.5 - FEH13
TAW_01 Winter 9.5 - FEH13
TAW_02 Winter 8.5 - FEH13
Are the storm durations likely to
be changed in the next stage of
the study, e.g. by optimisation
within a hydraulic model?
Yes, all inflow hydrographs will use a 9.5 hour storm
duration and an areal reduction factor based on the
TAW_01 location. This is the flow estimation point closest
to the site of interest (development site).
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 15
4.4 Flood estimates from the ReFH2 method
Site
code
Flood peak (m3/s) for the following AEP (%) events
50 20 10 5 3.33 2 1.33 1 0.5 0.2 0.1
TWR_01 58 74 85 96 103 112 120 125 142 170 199
TAW_01 160 204 235 265 284 309 330 346 389 465 541
TAW_02 111 143 165 187 201 219 234 245 276 329 382
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 16
5 Discussion and summary of results
5.1 Comparison of results from different methods
This table compares peak flows from various methods with those from the FEH Statistical
method at example sites for two key return periods. Blank cells indicate that results for a
particular site were not calculated using that method.
Site
code
Ratio of peak flow to FEH Statistical peak
50% AEP 1% AEP
ReFH2/FEH ReFH2/FEH
TWR_01 0.89 0.80
TAW_01 0.95 0.94
TAW_02 0.97 0.97
5.2 Final choice of method
Choice of method and
reasons
The comparison of 50% and 1% AEP flows in Section 5.1 shows that
the ReFH2 peak flow estimates are lower than the FEH Statistical
flows. The difference is larger for the Afon Twrch, with the 1% AEP
event estimate from ReFH2 method being 20% lower than that from
the FEH Statistical method. For the Afon Tawe the difference is only
3%-6%.
FEH Statistical is the preferred method for generating the design peak
flow estimates for the study catchment as QMED has been improved
using local donors. ReFH2 is based on catchment descriptors only. It
is recommended that the FEH Statistical method peak flow estimates
are taken forward but with the ratio from ReFH2 applied to events
above 1% AEP, as recommended in NRW guidance12.
How will the flows be
applied to a hydraulic
model?
TWR_01 will be input as a point inflow to the top of the Afon Twrch
watercourse model extent in the hydraulic model. TAW_02 will be
input as a point inflow to the top of the Afon Tawe watercourse model
extent in the hydraulic model. TAW_01A will be distributed along the
Afon Tawe, between TAW_02 and TAW_01. Modelled flows will be
checked against the target flows at TAW_01 and adjustments made
to the intervening area hydrographs, if required.
5.3 Assumptions, limitations and uncertainty
List the main
assumptions made
(specific to this
study)
The main assumptions are:
• The FEH Web Service catchment boundary definition is
reasonable, although there are some inaccuracies when
compared to contour data and watercourse lines.
• Stations 58008 and 59001 are the most representative local
donors with similar catchment descriptors and characteristics
to the three study catchments and hence a similar flood
response.
• The pooling groups used to define the growth curve for the
FEH Statistical method is representative of the catchments.
• The ReFH2 model generates a representative hydrograph
shape for the watercourses.
12 Natural Resources Wales. December 2017. GN008. Flood estimation: technical guidance.
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 17
Discuss any particular
limitations
The main limitations are:
• There is no reported flood history for the development site
against which the design peak flow estimates can be verified.
• There is no flow gauge on the Afon Twrch which can be used
as a donor.
Give what
information you can
on uncertainty in the
results,
A UK average measure of uncertainty for the FEH Statistical method
is presented in a technical report13 generated by a R&D project into
FEH, local data and uncertainty (Environment Agency funded
consortium of JBA, CEH and others).
The 95% confidence limits for a 1% AEP flood estimate for a rural
catchment (URBEXT2000 < 0.03) are 0.47-2.12 times the best estimate
with a donor adjustment of QMED (one donor). Note: Confidence
limits are provided for no donor, one donor and six donors; values are
not provided for two donors.
It is not possible to directly quantify the uncertainty for the ReFH2
method.
Comment on the
suitability of the
results for future
studies,
The design peak flow estimates and hydrographs were derived for the
purposes of this modelling study. If peak flow estimates and
hydrographs are required for a different purpose it is recommended
that, at minimum, a review of the results is carried out.
5.4 Checks
Are the results
consistent, for
example at
confluences?
Yes, flow estimates increase downstream. The sum of flows at
TWR_01 and TAW_02 are larger than the flow at TAW_01, as would
be expected (peak flows from the Twrch and Tawe are unlikely to
coincide).
What do the results
imply regarding the
return periods of
floods during the
period of record?
There are no gauges within the study area to compare flow estimates
to.
What is the range of
100-year growth
factors? Is this
realistic?
The 1% AEP growth factor for the methods is:
• FEH Statistical: 2.18 - 2.38
• ReFH2: 2.15 - 2.20
The typical range is 2.1-4.0 therefore both methods are at the lower
extent of, but within, the range. This is consistent with the 2016
study.
If 1000-year flows
have been derived,
what is the range of
ratios for 1000-year
flow over 100-year
flow?
The 0.1% / 1% AEP event ratio for the methods is:
• FEH Statistical: 1.48 - 1.57
• ReFH2: 1.56 – 1.59
How do the results
compare with those
of other studies?
Explain any
differences and
conclude which
results should be
preferred.
JBA Consulting undertook flood modelling studies in 2013 and 2016,
one of the flow estimation points is at the same location as used for
this study (TWR_01) – the Afon Twrch just upstream of the confluence
with the Afon Tawe. The flow estimates for all three studies can
therefore be directly compared. The estimates for the 50%, 1% and
0.1% AEP events are provided in the table below.
Study Flow (m3/s) for the following AEP (%) events
13 Environment Agency, 2017. Using local data to reduce uncertainty in flood frequency estimation.
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 18
50 1 0.1
2013 66 152 297
2016 68 146 231
2019 68 157 249
There is limited information regarding the approach undertaken for
the 2013 study. However, the main difference for the 2013 study to
the 2016 and current study is that QMED was adjusted using the
Gurnos gauging station and the adjustment was applied directly
without the distance weighting. The Gurnos gauge was not used for
this study or in 2016 as it has been level-only since 2003. Also a storm
duration of 6.5hr was used for the 2013 study.
The 2019 50% AEP event flow estimate is ~2% lower than the 2016
study. The 2019 1% and 0.1% AEP event flow estimates are ~7%
larger than the 2016 study.
The 2016 study FEH Statistical flow estimates are based on QMED
adjusted using the same donors as this study (58008 and 59001). A
storm duration of 8.5hr was also used in the 2016 study to generate
ReFH2 peak flow estimates. However, a slightly different pooling
group was used in the 2019 study compared to the 2016 study which
may explain some differences in flow estimates.
The latest peak flow data (NRFA v7) has been used in the pooling
group analysis for this 2019 study. This contains an additional two
years of data (for gauging stations in England, Wales & Northern
Ireland) compared to the dataset used in the 2016 study. Therefore
the 2019 results should be preferred as these use the latest methods,
data and guidance.
Are the results
compatible with the
longer-term flood
history?
There is no information on reported flooding of the study site to make
this assessment.
Describe any other
checks on the results
Following the initial model run, the flows will be sense-checked to
ensure that the flow inputs result in realistic outputs. Modelled flows
at TAW_01 will be checked against target flows for this location and
adjustments made to the intervening area hydrographs, if required.
5.5 Final results
These estimates have been generated using the FEH Statistical method with QMED adjusted using an equal weighting of Stations 59001 and 58008 for TWR_01, TAW_01 & TAW_02. The ReFH2 ratio has been applied to events above the 1% AEP event.
Site
code
Flood peak (m3/s) for the following AEP (%) events
50 20 10 5 3.33 2 1.33 1 0.5 0.2 0.1
TWR_01 66 85 99 114 124 137 148 157 177 212 249
TAW_01 169 213 245 278 299 327 351 369 415 495 577
TAW_02 115 146 168 190 205 224 240 252 284 338 393
If flood hydrographs are needed for the next stage of
the study, where are they provided?
Hydrographs.xlsx
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 19
6 Annex
TWR_01 Pooling Group
Station Distance Years
of data QMED
AM L-CV L-
SKEW Discordancy
46007 (West Dart @ Dunnabridge) 0.188 36 70.1 0.177 0.162 0.073
58006 (Mellte @ Pontneddfechan) 0.38 46 86.9 0.170 0.097 1.755
47014 (Walkham @ Horrabridge) 0.411 44 39.6 0.221 0.235 0.679
21030 (Megget Water @ Henderland) 0.464 13 77.7 0.216 0.074 2.352
84020 (Glazert Water @ Milton of Campsie) 0.507 37 54.2 0.132 0.075 1.497
21017 (Ettrick Water @ Brockhoperig) 0.524 41 60.4 0.203 0.276 0.278
55004 (Irfon @ Abernant) 0.534 45 56.5 0.159 0.255 1.560
73009 (Sprint @ Sprint Mill) 0.607 48 42.1 0.180 0.199 0.044
73017 (Kent @ Bowston) 0.624 18 63.2 0.226 0.403 1.206
73011 (Mint @ Mint Bridge) 0.625 48 54.8 0.215 0.303 0.394
76014 (Eden @ Kirkby Stephen) 0.673 46 86.8 0.170 -0.026 1.488
48001 (Fowey @ Trekeivesteps) 0.693 48 17.5 0.22 0.276 0.409
74001 (Duddon @ Duddon Hall) 0.783 50 120.913 0.152 0.244 1.265
Total 520
Weighted means 0.187 0.196
TAW_01 Pooling Group
Station Distance Years of
data QMED
AM L-CV L-
SKEW Discordancy
58002 (Neath @ Resolven) 0.345 39 220.0 0.149 0.233 0.733
79004 (Scar Water @ Capenoch) 0.441 43 132.9 0.087 0.070 1.998
72015 (Lune @ Lunes Bridge) 0.447 38 202.1 0.145 0.150 0.519
55026 (Wye @ Ddol Farm) 0.448 48 115.2 0.174 0.125 0.592
73012 (Kent @ Victoria Bridge) 0.505 39 141.8 0.209 0.286 0.760
56006 (Usk @ Trallong) 0.506 44 163.6 0.193 0.148 1.204
60006 (Gwili @ Glangwili) 0.507 49 78.5 0.159 0.167 0.300
75009 (Greta @ Low Briery) 0.544 45 110.9 0.234 0.273 0.985
4005 (Meig @ Glenmeanie) 0.569 21 111.3 0.179 0.244 1.093
16003 (Ruchill Water @ Cultybraggan) 0.581 45 148.1 0.145 0.058 1.157
59001 (Tawe @ Ynystanglws) 0.598 43 253.1 0.123 0.248 1.554
81003 (Luce @ Airyhemming) 0.630 40 164.2 0.166 0.091 0.551
76004 (Lowther @ Eamont Bridge) 0.638 55 110.385 0.244 0.19 1.554
Total 549
Weighted means 0.169 0.174
AAA-JBAU-XX-00-RP-HO-0001-S0-P01-FEH_Calculation_Record 20
TAW_02 Pooling Group
Station Distance Years of
data QMED
AM L-CV L-
SKEW Discordancy
74001 (Duddon @ Duddon Hall) 0.223 50 120.9 0.152 0.244 1.063
16003 (Ruchill Water @ Cultybraggan) 0.232 45 148.1 0.145 0.058 0.461
58012 (Afan @ Marcroft Weir) 0.254 37 94.9 0.159 0.093 1.264
55004 (Irfon @ Abernant) 0.41 45 56.5 0.159 0.255 0.900
47024 (Tavy @ Tavistock Abbey Bridge) 0.43 23 81.8 0.206 0.139 1.390
58006 (Mellte @ Pontneddfechan) 0.508 46 86.9 0.170 0.097 1.366
96004 (Strathmore @ Allnabad) 0.514 19 198.5 0.183 0.234 0.474
73017 (Kent @ Bowston) 0.54 18 63.2 0.226 0.403 1.943
46008 (Avon @ Loddiswell) 0.585 37 63.1 0.171 0.069 1.708
4005 (Meig @ Glenmeanie) 0.636 21 111.3 0.179 0.244 0.202
60006 (Gwili @ Glangwili) 0.708 49 78.5 0.159 0.167 0.148
47020 (Inny @ Bealsmill) 0.727 33 35.0 0.198 0.135 0.998
73011 (Mint @ Mint Bridge) 0.728 48 54.835 0.215 0.303 0.734
78004 (Kinnel Water @ Redhall) 0.747 40 78.224 0.118 0.011 1.35
Total 511
Weighted means 0.172 0.168
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