chapter 3 site selection and option appraisal · pdf filethese devices are like underwater...
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Environmental StatementChapter 3. Site Selection and Option Appraisal
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal
Contents
3.0 Site Selection and Option Appraisal
3.1 Introduction .............................................................................................................................. 1
3.2 Marine renewables and wider site selection ............................................................................ 1
3.3 Positioning the tidal lagoon within Swansea Bay ..................................................................... 3
3.4 Option assessment for the Lagoon design ............................................................................... 4
3.4.1 Introduction ...................................................................................................................... 4
3.4.2 Evolution of the Lagoon shape ......................................................................................... 4
3.5 Turbines and sluice gates ........................................................................................................ 16
3.5.1 Introduction .................................................................................................................... 16
3.5.2 Turbines .......................................................................................................................... 17
3.5.3 Sluice gates ..................................................................................................................... 18
3.6 Construction method choices ................................................................................................. 18
3.6.1 Turbine-housing construction......................................................................................... 18
3.6.2 Offshore temporary bund ............................................................................................... 19
3.6.3 Soft options ..................................................................................................................... 19
3.6.4 Hard options ................................................................................................................... 19
3.7 Grid connection ...................................................................................................................... 20
3.8 Water quality optimisation ..................................................................................................... 27
3.9 Decommissioning options....................................................................................................... 31
3.10 Project infrastructure ............................................................................................................. 35
3.10.1 Introduction .................................................................................................................... 35
3.10.2 Sports and recreation ..................................................................................................... 35
3.10.3 Mariculture opportunities .............................................................................................. 36
3.11 References .............................................................................................................................. 39
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 1
3.0 Site Selection and Option Appraisal
3.1 Introduction
3.1.0.1 The objective of this Chapter is to set out the option assessment stages which have been
undertaken for the Project. This has been an iterative process, from site selection
through to the development of the overall design of the tidal lagoon and onshore
infrastructure as presented in Chapter 4, Project Description.
3.1.0.2 The following sections will present the iterative processes which have been undertaken
including:
a) Marine renewables and wider site selection ("why Swansea Bay?");
b) Positioning the Lagoon within Swansea Bay;
c) Option assessment for Lagoon design;
d) Turbines and sluice gates;
e) Construction method choices;
f) Grid connection options;
g) Water quality optimisation applications;
h) Decommissioning options; and
i) Project infrastructure – including sports and recreation, mariculture opportunities,
education and art.
3.2 Marine renewables and wider site selection
3.2.0.1 In order to capture energy from the sea there are three marine renewable options that
are being progressed in the UK: wave power, tidal stream and tidal range.
3.2.0.2 Wave power is dependent on the movement of the sea surface and the use of swell or
large moving offshore waves to generate energy. The devices used to capture wave
power tend to be large floating pontoons located off the coast. They are dependent
upon weather conditions, which affect wave energy.
3.2.0.3 Tidal stream power is focused on capturing the energy from the flow of currents during
the ebb and flood tides. These devices are like underwater windmills (turbines) which
turn with the flow of the current. Each turbine can be placed on freestanding
foundations or a number can be grouped on a single foundation frame. Good locations
for these devices are in high tidal flow areas, such as where flows are channelled
between landforms and hence the currents increase.
3.2.0.4 Tidal range power requires an area where there is a large difference (range) between
high and low water caused by tides. The technology works by holding back the tide in a
lagoon or other impoundment (such as in an estuary) for a short period of time, thereby
creating a difference in water level inside and outside the structure (called head). When
the water is released, energy is generated. This technology has been used in estuarial
barrages for many years (e.g. at La Rance in France, which has operated since 1966).
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 2
3.2.0.5 The tidal range of a particular location is dependent, in part, on its position relative to
the equator, but more on other physical factors in the area e.g. topography, water depth,
shoreline configuration, size of the ocean basin etc. The highest tidal range in the world
can be found in the Bay of Fundy in Nova Scotia (>11m), and this is closely followed by
Swansea and the Bristol Channel, UK (>9m).
3.2.0.6 Figure 3.1 below illustrates the areas around England and Wales where particularly high
tidal ranges are found (coloured yellow/orange). This, combined with the fact that the
time of high tide varies around the coast of the UK, gives the potential to produce base
load electricity, around the clock, from a reliable, renewable resource.
Figure 3.1 Areas of high tidal range around England and Wales
3.2.0.7 In addition to a good tidal range, a gently-sloping seabed (as found in Swansea Bay) is
also required for building lagoons. Finally, economies of scale apply, with bigger tidal
lagoons making cheaper electricity than smaller ones, which enhances the attractiveness
of larger bays.
3.2.0.8 To achieve the objective of constructing the first, purpose-built, tidal lagoon in the world,
a balance was sought between optimum tidal range, an appropriate scale, and
opportunities for providing additional benefits to the local area (e.g. recreation and
regeneration). Swansea Bay provides all of these key elements.
Other studies
3.2.0.9 The UK Government has also considered marine renewable energy in its rounds of
Strategic Environmental Assessments (SEA) to inform licensing and leasing of the seabed
for energy uses. In SEA8 (2007), the Government considered the strategic use of the
southwest waters of England and Wales, including the Bristol Channel, for oil exploration
and renewable energy (such as wind). The conclusion of SEA8 states that the area has
not seen a large amount of development in relation to oil exploration or renewable
energy in the offshore zones, but that significant infrastructure development has taken
place in the densely populated coastal zones.
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 3
3.2.0.10 Offshore Energy Strategic Environmental Assessments 2 (OSEA2) is currently being
undertaken by the Department of Energy and Climate Change (DECC) to supersede the
assessment undertaken in SEA8 (and other) SEAs, and to inform the granting of leases
and licences in relation to territorial waters and the Renewable Energy Zone (of which
the Bristol Channel and Swansea Bay form a part). The assessment covers tidal range
development and defines its impacts. The consultation SEA (OSEA2) sets out how the
activities that follow the adoption of a plan or programme to license or lease tidal range
technologies will have certain broad impacts on the environment, which should be
considered in an environmental impact assessment.
3.2.0.11 OSEA2, once completed, will provide the assessed basis of a program for the licensing
and leasing of territorial sea in England and Wales. This includes tidal range technologies
aside from the Severn Barrage.
3.2.0.12 Further understanding of the potential size and distribution of wave and tidal resources
has been developed in a study by The Crown Estate (2012). The objective was to look at
the future potential for wave and tidal project development around the UK coast. The
study concluded that there are opportunities for tidal range schemes that can contribute
to the UK’s energy needs. In addition, the study noted that England and Wales share the
largest single area of tidal range resource, namely the Bristol Channel and Severn
Estuary.
3.3 Positioning the tidal lagoon within Swansea Bay
3.3.0.1 A number of key factors were used to select the position of the Project within the Bay.
These are described below.
3.3.0.2 Beach profile and depth of water: In order to minimise various environmental and
economic impacts, shallower water depth is preferred for lagoon development. Shallow
waters with gentle beach slopes are found at a number of areas in the Bay, including off
the Swansea Port and between Mumbles Headland and Singleton Park.
3.3.0.3 Beach recreational quality: As shallow water depth is preferred, this tends to occur
nearer to the shore and, as such, there is scope for material impacts on existing beach
uses. Within Swansea Bay there are two designated bathing beaches (Aberafan Sands
and Swansea Bay), and these have been avoided so as to preserve these amenities. The
site selected for the Project is on an intertidal area, which is not a designated bathing
area, and which is predominantly backed by the Swansea dockland.
3.3.0.4 Landfall: To construct landfalls for the seawalls of a lagoon (if it is land-attached - see
3.4.2 below), suitable sites are required. Some of the key elements of a good landfall
would include: minimising disruption to existing users of the land; the presence of good
local and wider transport infrastructure; availability of space for onshore facilities; and
the opportunity to provide additional regeneration and/or recreational opportunities to
the local area. Suitable shore profiles are also necessary.
3.3.0.5 Navigation: Positioning the lagoon such that it did not interfere with the operation of the
three ports in Swansea Bay (Swansea, Neath and Port Talbot) was a key factor. The
location between, but not affecting, the dredged approach channels of the ports of
Swansea and Neath was selected to minimise disruption to shipping.
3.3.0.6 Turbine depth: The marine turbines required for power generation have to be positioned
in sufficiently deep water to be permanently submerged. On current turbine dimensions
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 4
this requires 7m of permanent depth below Chart Datum, which can be achieved by
seabed excavation.
3.3.0.7 Conclusion: Taking all the factors above into consideration, the selected area for the
Project is located off Swansea Port. Here, the seabed is gently-sloping offshore, up to the
outer reaches of this area which achieve the required water depth for the turbines. The
use of western landfall point in an area of existing industrial/port uses provides
significant benefits in terms of: minimising impacts during construction; assisting with
transport logistics (i.e. supporting delivery of materials by sea); and providing space for
supporting facilities during construction and operation. The site also provides a relatively
simple electrical grid connection. During operation there would be potential for onshore
facilities with opportunities to enhance the local area. In terms of minimising disruption
to navigation, this can be achieved by siting the Project between, but not affecting, the
dredged approach channels of the ports of Swansea and Neath.
3.4 Option assessment for the Lagoon design
3.4.1 Introduction
3.4.1.1 The lagoon design has changed throughout the evolution of the Project to find the best
solution with regards to energy generation, environmental considerations and cost
viability. This section describes how the lagoon design has changed, and what has led to
the proposals presented in Chapter 4, Project Description.
3.4.2 Evolution of the Lagoon shape
3.4.2.1 At the early stages of the Project, the initial idea was for an entirely offshore lagoon
impounding structure, without any landfall (Table 3.1). It was thought that this design
would create enough energy for viability, and would be beneficial to coastal processes
and sediment transport by allowing flows around the landward perimeter of the lagoon.
3.4.2.2 However, preliminary energy and cost modelling showed that the offshore lagoon option
was not commercially viable, as the ratio of wall length to enclosed area was too low. In
addition to this, initial high level (low resolution) coastal process modelling showed that
significant current movement would occur on the landward side of the lagoon as a result
of tides, potentially significantly increasing scouring.
3.4.2.3 This resulted in a change to a land-attached lagoon design. By becoming land-attached,
the lagoon was more economically viable, as approximately 30% of the impounding wall
comprises existing land, instead of manmade seawall. This also provided a simple,
protected cable route within the seawall, and easier access to the lagoon for both the
construction and operation purposes.
3.4.2.4 This necessary design change not only made the lagoon viable, but also completely
changed the vision of what the lagoon could achieve. The land attachment meant that
the lagoon could now, not only provide reliable renewable energy, it could also provide a
potential recreational and sporting resource as well as other opportunities. These
opportunities are discussed further in Section 3.10
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 5
3.4.2.5 The lagoon shape has evolved throughout the preliminary design process, as the
understanding of the energy modelling, turbines, cost modelling and environmental
constraints has grown. Approximately 20 different lagoon layout options have been
considered ranging from a small, 6.0km2, offshore lagoon (A) to a very large, 17km
2, land-
attached lagoon (L). The main designs that were considered are presented in Table 3.1.
3.4.2.6 As part of the selection process, the chosen layout, Option (J3), was optimised based on
potential energy production and also took into consideration preliminary water quality
modelling, initial high level coastal processes modelling (including changes in current
movement), navigation risk, geotechnical issues, engineering (in terms of wall design),
wall depth and overall cost.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
6
Ta
ble
3.1
T
ida
l La
go
on
Sw
an
sea
Ba
y,
lag
oo
n d
esi
gn
ite
rati
on
s
LAG
OO
N D
ES
IGN
C
ON
ST
RA
INT
S S
UM
MA
RY
All
la
go
on
de
sig
n o
pti
on
s T
he
de
sig
n i
tera
tio
n p
roce
ss r
an
fro
m D
ece
mb
er
20
11
to
Ju
ly 2
01
3,
en
com
pa
ssin
g 1
5 m
ain
la
go
on
op
tio
ns
sho
wn
be
low
.
Co
nst
rain
ts a
pp
lyin
g t
o a
ll o
pti
on
s ca
n b
e s
um
ma
rise
d a
s fo
llo
ws:
- E
ne
rgy
ou
tpu
t –
pri
ma
rily
dri
ve
n b
y t
he
vo
lum
e o
f ca
ptu
red
wa
ter:
mo
re w
ate
r p
rovi
de
s m
ore
po
we
r
- V
iab
ilit
y –
pri
ma
rily
dri
ve
n b
y t
he
ra
tio
of
the
le
ng
th o
f se
aw
all
to
th
e a
rea
of
sea
be
d (
an
d t
he
refo
re t
he
vo
lum
e o
f
wa
ter)
en
clo
sed
. E
lon
ga
ted
la
go
on
sh
ap
es
ha
ve
a l
ess
eff
icie
nt
rati
o t
ha
n r
ou
nd
ed
sh
ap
es
- B
ath
ym
etr
y –
de
ep
wa
ter
req
uir
es
a h
igh
er
sea
wa
ll,
wit
h a
gre
ate
r a
sso
cia
ted
co
st
- C
on
stru
ctio
n m
eth
od
– u
se o
f G
eo
tub
es®
in
th
e s
ea
wa
ll w
as
pre
ferr
ed
fro
m t
he
sta
rt,
bu
t th
e m
eth
od
of
bu
ild
ing
th
e
turb
ine
ho
usi
ng
ch
an
ge
d f
rom
flo
ati
ng
pre
-ca
st c
ais
son
s in
to p
osi
tio
n,
to b
uil
din
g a
co
ffe
rda
m w
ith
in w
hic
h t
o
con
stru
ct t
he
tu
rbin
e h
ou
sin
g i
n s
itu
. T
his
ch
an
ge
in
flu
en
ced
so
me
asp
ect
s o
f la
go
on
de
sig
n d
eta
il a
s se
t o
ut
be
low
- D
red
ge
d c
ha
nn
els
– p
rovi
din
g a
cce
ss t
o S
wa
nse
a D
ock
s (v
ia t
he
Riv
er
Ta
we
) a
nd
Ne
ath
Ha
rbo
ur
(via
th
e R
ive
r N
ea
th)
- C
rym
lyn
Bu
rro
ws
SS
SI
– r
eq
uir
ing
pro
tect
ion
NO
TE
: E
ach
la
go
on
op
tio
n h
as
be
en
re
vie
we
d b
elo
w w
ith
re
fere
nce
to
th
e m
ost
re
lev
an
t co
nst
rain
ts o
nly
.
LAG
OO
N D
ES
IGN
D
ES
IGN
DA
TE
& R
AT
ION
ALE
C
ON
SU
LTE
E /
EIA
FE
ED
BA
CK
& D
EC
ISIO
N
CO
NS
ULT
AT
ION
PH
AS
E:
“Ea
rly
pro
ject
de
fin
itio
n a
nd
in
form
ing
th
e E
IA”
De
cem
be
r 2
01
1 -
Ap
ril
20
12
Op
tio
n A
. O
ffsh
ore
la
go
on
, si
mil
ar
to p
rop
osa
ls
init
iate
d b
y T
ida
l E
lect
ric
Ltd
(2
00
2-2
00
6)
on
th
e
ass
um
pti
on
th
at
an
off
sho
re l
ag
oo
n w
ou
ld h
av
e
low
er
imp
act
on
co
ast
al
pro
cess
es
com
pa
red
to
a
lan
d-a
tta
che
d l
ag
oo
n b
y a
llo
win
g w
ate
r fl
ow
be
twe
en
th
e l
an
dw
ard
wa
ll o
f th
e l
ag
oo
n a
nd
th
e
po
rt.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:0.6
Ea
ste
rly
tu
rbin
e a
lig
nm
en
t.
Lag
oo
n b
elo
w 1
00
MW
in
sta
lle
d c
ap
aci
ty a
nd
no
t a
n
NS
IP.
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h l
ev
el
coa
sta
l p
roce
ss m
od
ell
ing
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gg
est
ed
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nif
ica
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ea
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urr
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etw
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re
ar
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ll o
f th
e l
ag
oo
n a
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e s
ho
re
ad
jace
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wa
nse
a P
ort
at
cert
ain
sta
tes
of
the
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e,
wh
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uld
ha
ve s
ign
ific
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t e
rosi
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po
ten
tia
l b
eh
ind
th
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oo
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ter
qu
ali
ty m
od
ell
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in
dic
ate
d t
ha
t u
nd
er
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avy
ra
infa
ll
con
dit
ion
s th
e r
ed
uce
d w
ate
r q
ua
lity
in
th
e R
ive
r T
aw
e w
ou
ld b
e
en
tra
ine
d b
eh
ind
th
e l
ag
oo
n k
ee
pin
g i
t in
sho
re f
or
an
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cre
ase
d
pe
rio
d o
f ti
me
. In
ad
dit
ion
, th
e e
ast
erl
y d
isch
arg
e p
osi
tio
n o
f th
e
turb
ine
ho
use
wo
uld
re
sult
in
th
e s
torm
wa
ter
fro
m t
he
ou
tfa
ll
aff
ect
ing
Ab
era
fan
be
ach
.
Ina
de
qu
ate
via
bil
ity
ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
.
Op
tio
n r
eje
cte
d.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
7
De
cem
be
r 2
01
1-
Ap
ril
20
12
Op
tio
n A
1.
Fir
st l
an
d-a
tta
che
d o
pti
on
re
vie
we
d i
n
pa
rall
el
wit
h o
ffsh
ore
Op
tio
n A
, a
bo
ve
, to
co
mp
are
an
d c
on
tra
st p
ote
nti
al
imp
act
s. A
pp
roxi
ma
tely
30
%
of
the
im
po
un
dm
en
t m
ad
e u
p b
y l
an
d i
nst
ea
d o
f
sea
wa
ll,
red
uci
ng
le
ng
th o
f se
aw
all
(a
nd
co
st)
acc
ord
ing
ly.
Se
aw
all
no
w p
rov
ide
s a
gri
d c
on
ne
ctio
n
rou
te w
ith
in t
he
wa
ll s
tru
ctu
re (
inst
ea
d o
f o
n t
he
sea
be
d),
as
we
ll a
s e
asy
acc
ess
du
rin
g t
he
con
stru
ctio
n a
nd
op
era
tio
n p
eri
od
s.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:0.7
7
Ea
ste
rly
tu
rbin
e a
lig
nm
en
t. ‘
Lip
’ a
t tu
rbin
e h
ou
sin
g
de
sig
ne
d t
o p
rote
ct t
he
ho
usi
ng
fro
m p
reva
ilin
g
we
ath
er/
sea
s d
uri
ng
bo
th c
on
stru
ctio
n (
of
a
cais
son
s-b
ase
d h
ou
sin
g)
an
d o
pe
rati
on
.
Lag
oo
n b
elo
w 1
00
MW
in
sta
lle
d c
ap
aci
ty a
nd
no
t a
n
NS
IP.
Hig
h l
ev
el
coa
sta
l p
roce
sse
s m
od
ell
ing
su
gg
est
ed
a r
ed
uce
d o
ve
rall
coa
sta
l p
roce
ss i
mp
act
re
lati
ve
to
off
sho
re O
pti
on
A.
Wa
ter
qu
ali
ty m
od
ell
ing
in
dic
ate
d t
ha
t th
e e
ast
erl
y d
isch
arg
e
po
siti
on
of
the
tu
rbin
e h
ou
se w
ou
ld r
esu
lt i
n t
he
sto
rm w
ate
r fr
om
the
ou
tfa
ll i
mp
act
ing
on
Ab
era
fan
be
ach
.
Ina
de
qu
ate
via
bil
ity
ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
.
Op
tio
n r
eje
cte
d.
Ho
we
ve
r, l
an
d-a
tta
che
d l
ag
oo
ns
ide
nti
fie
d a
s th
e p
refe
rre
d o
pti
on
for
de
ve
lop
me
nt
an
d f
urt
he
r co
nsu
lta
tio
n o
n t
he
gro
un
ds
of:
red
uce
d e
nvi
ron
me
nta
l im
pa
ct;
incr
ea
sed
via
bil
ity
; si
mp
ler
gri
d
con
ne
ctio
n;
ea
se o
f a
cce
ss;
recr
ea
tio
na
l o
pp
ort
un
itie
s cr
ea
ted
by
tha
t a
cce
ss.
Ma
rch
20
12
– A
pri
l 2
01
2
Op
tio
n B
. E
xplo
rati
on
of
larg
er
lan
d-a
tta
che
d
op
tio
ns,
aim
ing
to
im
pro
ve r
ati
o o
f se
aw
all
to
en
clo
sed
are
a,
an
d e
nh
an
ce v
iab
ilit
y f
rom
gre
ate
r
en
erg
y o
utp
ut.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:0.9
8
So
uth
ea
ste
rly
tu
rbin
e a
lig
nm
en
t.
Lag
oo
n b
elo
w 1
00
MW
in
sta
lle
d c
ap
aci
ty a
nd
no
t a
n
NS
IP.
Ea
rly
wa
ter
qu
ali
ty m
od
ell
ing
su
gg
est
ed
in
term
itte
nt
sto
rm w
ate
r
fro
m s
ew
ag
e o
utf
all
, in
co
mb
ina
tio
n w
ith
so
uth
ea
ste
rly
tu
rbin
e
ali
gn
me
nt,
wo
uld
ha
ve
po
ten
tia
l to
ad
vers
ely
aff
ect
Ab
era
von
ba
thin
g b
ea
ch.
Ina
de
qu
ate
via
bil
ity
ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
.
Op
tio
n r
eje
cte
d.
Lan
d-a
tta
che
d,
we
st t
o s
ou
the
rly
fa
cin
g l
ag
oo
n d
esi
gn
co
nfi
rme
d
as
pre
ferr
ed
op
tio
n.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
8
Ma
rch
20
12
– A
pri
l 2
01
2
Op
tio
n C
. A
lte
rna
tiv
e l
an
d-a
tta
che
d o
pti
on
,
con
sid
ere
d a
t th
e s
am
e t
ime
as
Op
tio
n B
, b
ut
wit
h
slig
htl
y s
ma
lle
r e
ncl
ose
d a
rea
an
d d
iffe
ren
t sh
ap
e.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:0.9
5
So
uth
-ea
ste
rly
tu
rbin
e a
lig
nm
en
t.
Lag
oo
n b
elo
w 1
00
MW
in
sta
lle
d c
ap
aci
ty a
nd
no
t a
n
NS
IP.
Wa
ter
qu
ali
ty i
ssu
es
the
sa
me
as
Op
tio
n B
, a
bo
ve
.
Ina
de
qu
ate
via
bil
ity
ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
.
Op
tio
n r
eje
cte
d.
Lan
d-a
tta
che
d,
we
st t
o s
ou
the
rly
fa
cin
g d
esi
gn
fo
r
turb
ine
ho
usi
ng
co
nfi
rme
d a
s p
refe
rre
d o
pti
on
fo
r fu
rth
er
de
sig
n
de
ve
lop
me
nt.
La
go
on
de
sig
n D
is
sho
wn
he
re s
et
ag
ain
st s
ele
cte
d l
arg
er
op
tio
ns,
de
scri
be
d b
elo
w,
for
sca
le.
Ap
ril
20
12
– A
pri
l 2
01
3
Op
tio
n D
. S
imil
ar
in s
cale
to
Op
tio
n B
bu
t w
ith
turb
ine
ho
usi
ng
fa
cin
g s
ou
thw
est
to
re
du
ce a
dve
rse
eff
ect
s o
n w
ate
r q
ua
lity
. In
itia
l m
od
ell
ing
de
mo
nst
rate
d t
ha
t a
tu
rbin
e h
ou
sin
g w
ith
a w
est
to
sou
the
rly
ali
gn
me
nt
wo
uld
no
t a
ffe
ct t
he
de
sig
na
ted
ba
thin
g b
ea
che
s.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:0.9
9.
En
erg
y
ou
tpu
ts g
oo
d,
an
d i
n e
xce
ss o
f 1
00
MW
(q
ua
lify
ing
the
pro
ject
as
an
NS
IP,
insi
de
th
e D
CO
pro
cess
),
init
ial
cost
s e
stim
ate
s p
osi
tiv
e.
Lag
oo
n d
esi
gn
D w
as
use
d f
or
the
EIA
Sco
pin
g
Re
po
rt (
Oct
ob
er
20
12
) a
nd
su
bje
ct t
o ‘
Issu
es
an
d
Op
tio
ns’
co
nsu
lta
tio
n (
No
ve
mb
er
20
12
to
Ap
ril
20
13
, b
elo
w).
Th
is o
pti
on
wa
s id
en
tifi
ed
in
Ap
ril
20
12
, a
nd
in
form
ed
a m
ore
de
tail
ed
pe
rio
d o
f co
st,
via
bil
ity
, b
ase
lin
e E
IA a
sse
ssm
en
t a
nd
info
rma
l co
nsu
lta
tio
n w
ith
ke
y s
tak
eh
old
ers
. D
uri
ng
th
is p
eri
od
, it
wa
s e
sta
bli
she
d t
ha
t la
go
on
s b
elo
w 1
00
MW
(a
nd
ou
tsid
e t
he
DC
O
pro
cess
) w
ere
no
t v
iab
le a
nd
sh
ou
ld b
e r
eje
cte
d.
De
tail
ed
co
st f
igu
res
rais
ed
qu
est
ion
s o
ve
r vi
ab
ilit
y f
rom
Ja
nu
ary
20
13
, a
nd
la
rge
r la
go
on
s b
eg
an
to
be
exp
lore
d b
y T
LSB
en
gin
ee
rs,
wit
h a
n i
mp
rov
ed
via
bil
ity
ra
tio
an
d h
en
ce g
rea
ter
po
ten
tia
l
en
erg
y o
utp
ut,
as
set
ou
t b
elo
w.
(Op
tio
n f
ina
lly
re
ject
ed
in
Ma
y 2
01
3).
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
9
EIA
SC
OP
ING
RE
PO
RT
: la
go
on
de
sig
n O
pti
on
D,
sub
mit
ted
to
th
e P
lan
nin
g I
nsp
ect
ora
te i
n O
cto
be
r 2
01
2,
resp
on
se r
ece
ive
d i
n N
ov
em
be
r 2
01
2
F
rom
Ja
nu
ary
20
13
, a
s co
nce
rns
ov
er
the
‘v
iab
ilit
y r
ati
o’
we
re r
ais
ed
ab
ou
t O
pti
on
D,
the
op
tio
ns
E t
o M
de
scri
be
d b
elo
w w
ere
in
ve
stig
ate
d.
Th
e p
roce
ss a
lso
ad
dre
sse
d t
he
he
igh
t o
f th
e s
ea
wa
ll i
n r
esp
on
se t
o w
av
e d
ata
. V
ari
ou
s o
f o
pti
on
s E
to
M w
ere
pre
sen
ted
as
alt
ern
ati
ve
s to
de
sig
n D
th
rou
gh
:
CO
NS
ULT
AT
ION
PH
AS
E:
“Iss
ue
s a
nd
Op
tio
ns
ph
ase
2,
lag
oo
n d
esi
gn
D w
ith
em
erg
ing
alt
ern
ati
ve
s E
-M a
s se
t o
ut
be
low
Wa
ll l
en
gth
9
.4km
Are
a
9
.4km
2
Inst
all
ed
ca
pa
city
25
0M
W
An
nu
al
ou
tpu
t (g
ross
)
4
00
GW
h
De
sig
n l
ife
5
0-1
00
yrs
He
igh
t o
f w
all
1
1-1
9m
Wa
ll a
bo
ve
lo
w w
ate
r
1
1.3
m
Wa
ll a
bo
ve
hig
h w
ate
r
2
.8m
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
10
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n E
. S
imil
ar
in f
orm
to
Op
tio
n D
bu
t la
rge
r a
nd
wit
ho
ut
the
tu
rbin
e h
ou
se ‘
lip
’. A
s n
ote
d a
bo
ve
, th
e
lip
wa
s in
ten
de
d t
o p
rote
ct t
he
tu
rbin
e h
ou
se f
rom
pre
vail
ing
we
ath
er/
sea
s d
uri
ng
bo
th c
on
stru
ctio
n
an
d o
pe
rati
on
, b
ut
wa
s p
rov
en
un
-ne
cess
ary
by
(i)
wa
ve
mo
de
llin
g a
nd
, (i
i) t
he
sh
ift
fro
m a
ca
isso
n-
ba
sed
co
nst
ruct
ion
me
tho
d t
o t
he
mo
re c
ost
-
eff
ect
ive
use
of
a c
off
erd
am
fo
r co
nst
ruct
ion
.
To
in
cre
ase
th
e l
ag
oo
n s
ize
, th
e w
all
s fo
r O
pti
on
E
ha
ve e
xte
nd
ed
so
uth
an
d e
ast
, w
ith
a n
ew
ea
ste
rn
lan
dfa
ll o
uts
ide
Sw
an
sea
Do
cks.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.1
6
Lag
oo
n d
esi
gn
E a
nd
a n
um
be
r o
f la
rge
r o
pti
on
s (b
elo
w)
we
re
exp
lore
d i
n p
ara
lle
l, b
ase
d o
n v
ari
ou
s e
ng
ine
eri
ng
re
qu
ire
me
nts
an
d d
esi
red
en
erg
y y
ield
s. T
he
op
tio
ns
rais
ed
ke
y i
ssu
es,
in
clu
din
g
the
la
go
on
’s r
ela
tio
nsh
ip w
ith
Cry
mly
n B
urr
ow
s S
SS
I a
nd
th
e N
ea
th
dre
dg
ed
ch
an
ne
l. S
tak
eh
old
ers
qu
eri
ed
wh
eth
er
bu
ild
ing
th
e
lag
oo
n w
all
ou
tsid
e t
he
SS
SI
wo
uld
ca
use
mo
re o
r le
ss i
mp
act
th
an
cro
ssin
g,
or
ev
en
en
com
pa
ssin
g,
the
SS
SI
an
d r
eq
ue
ste
d t
ha
t
mo
de
llin
g s
ho
uld
in
form
th
e d
eci
sio
n.
In r
esp
on
se,
ad
dit
ion
al,
hig
h l
ev
el
mo
de
llin
g w
as
con
du
cte
d o
n k
ey
op
tio
ns
sele
cte
d f
rom
em
erg
ing
de
sig
ns
E t
o M
in
ord
er
to t
est
de
sig
n a
ssu
mp
tio
ns
ab
ou
t th
e l
ag
oo
n’s
re
lati
on
ship
wit
h t
he
SS
SI
wh
ich
co
uld
th
en
be
ap
pli
ed
to
oth
er
de
sig
n i
tera
tio
ns
as
req
uir
ed
.
Th
e o
pti
on
s/re
lati
on
ship
s te
ste
d w
ere
:
- O
pti
on
J –
av
oid
th
e S
SS
I
- O
pti
on
K –
cro
ss t
he
SS
SI
- O
pti
on
L –
en
com
pa
ss t
he
SS
SI
Op
tio
n E
wa
s u
ltim
ate
ly r
eje
cte
d d
ue
to
du
e t
o p
ote
nti
al
ad
ve
rse
imp
act
on
Cry
mly
n B
urr
ow
s S
SS
I.
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n F
. S
imil
ar
to O
pti
on
E b
ut
full
y e
nco
mp
ass
ing
the
SS
SI
wit
h a
vie
w t
ha
t th
is m
ay
off
er
pro
tect
ion
to
the
du
ne
are
a.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.3
0
Co
nce
rns
we
re r
ais
ed
by
mu
ltip
le s
tak
eh
old
ers
(e
.g.
EA
/CC
W,
wh
ich
su
bse
qu
en
tly
be
cam
e N
RW
) a
bo
ut
en
com
pa
ssin
g C
rym
lyn
Bu
rro
ws
an
d p
rev
en
tin
g s
an
d f
ee
d t
o t
he
SS
SI.
Ea
ste
rn l
an
dfa
ll i
s in
an
iso
late
d l
oca
tio
n f
or
ma
ste
rpla
nn
ing
an
d
recr
ea
tio
na
l a
mb
itio
ns.
Op
tio
n u
ltim
ate
ly r
eje
cte
d a
fte
r si
gn
ific
an
t co
nce
rns
rais
ed
by
sta
ke
ho
lde
rs o
ve
r e
nco
mp
ass
ing
Cry
mly
n B
urr
ow
s S
SS
I.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
11
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n G
. La
rge
la
go
on
av
oid
ing
th
e S
SS
I w
hil
e
ma
xim
isin
g i
mp
ou
nd
ed
are
a,
wit
h g
oo
d w
all
to
are
a
rati
o a
nd
hig
h p
ote
nti
al
en
erg
y o
utp
ut.
Fir
st o
pti
on
s
to e
xplo
re r
elo
cati
on
of
Ne
ath
dre
dg
ed
ch
an
ne
l
(alo
ng
wit
h H
, b
elo
w).
Hig
h c
ap
ita
l co
st d
ue
to
ext
en
de
d w
all
le
ng
th a
nd
de
ep
wa
ter
at
sou
the
ast
corn
er.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.3
2
Ne
ath
Po
rt A
uth
ori
ty (
NP
A)
rais
ed
ob
ject
ion
s to
th
e r
elo
cati
on
of
the
dre
dg
ed
ch
an
ne
l. A
lso
, w
ate
r q
ua
lity
mo
de
llin
g s
ho
we
d t
ha
t
cha
nn
el
relo
cati
on
ha
d t
he
po
ten
tia
l to
re
du
ce w
ate
r q
ua
lity
at
Ab
era
fan
be
ach
du
rin
g w
et
we
ath
er
(co
nce
rns
rais
ed
by
mu
ltip
le
sta
ke
ho
lde
rs).
Op
tio
n r
eje
cte
d.
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n H
. La
rge
la
go
on
en
cro
ach
ing
on
SS
SI
wit
h
go
od
wa
ll t
o a
rea
ra
tio
an
d h
igh
po
ten
tia
l e
ne
rgy
ou
tpu
t. F
irst
op
tio
ns
to e
xplo
re r
elo
cati
on
of
Ne
ath
dre
dg
ed
ch
an
ne
l (a
lon
g w
ith
G,
ab
ov
e).
Hig
h c
ap
ita
l
cost
du
e t
o e
xte
nd
ed
wa
ll l
en
gth
an
d d
ee
p w
ate
r a
t
sou
the
ast
co
rne
r.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.5
1
As
ab
ov
e,
Ne
ath
Po
rt A
uth
ori
ty (
NP
A)
rais
ed
ob
ject
ion
s to
th
e
relo
cati
on
of
the
dre
dg
ed
ch
an
ne
l. A
lso
, w
ate
r q
ua
lity
mo
de
llin
g
sho
we
d t
ha
t ch
an
ne
l re
loca
tio
n h
as
the
po
ten
tia
l to
re
du
ce b
ea
ch
wa
ter
qu
ali
ty a
t A
be
rafa
n d
uri
ng
we
t w
ea
the
r (c
on
cern
s ra
ise
d b
y
mu
ltip
le s
tak
eh
old
ers
).
Hig
h l
ev
el
coa
sta
l p
roce
ss m
od
ell
ing
(o
n O
pti
on
K,
be
low
) sh
ow
ed
po
ten
tia
l in
cre
ase
d a
dv
ers
e i
mp
act
on
Cry
mly
n B
urr
ow
s S
SS
I
rela
tiv
e t
o d
esi
gn
s (O
pti
on
J)
wh
ich
av
oid
th
e S
SS
I.
Op
tio
n r
eje
cte
d.
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n I
. V
ery
la
rge
la
go
on
en
com
pa
ssin
g S
SS
I, w
ith
go
od
wa
ll t
o a
rea
ra
tio
an
d h
igh
po
ten
tia
l e
ne
rgy
ou
tpu
t. R
elo
cati
on
of
Ne
ath
dre
dg
ed
ch
an
ne
l
ne
cess
ary
. V
ery
hig
h c
ap
ita
l co
st d
ue
to
ext
en
de
d
wa
lls.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.5
2
Hig
h l
ev
el
coa
sta
l p
roce
ss m
od
ell
ing
(o
n O
pti
on
L,
be
low
) in
dic
ate
d
a h
igh
er
lev
el
of
imp
act
on
Cry
mly
n B
urr
ow
s S
SS
I re
lati
ve
to
Op
tio
n
J (a
vo
idin
g t
he
SS
SI)
.
Re
loca
tio
n o
f th
e N
ea
th C
ha
nn
el
als
o h
ad
po
ten
tia
l to
re
du
ce
wa
ter
qu
ali
ty a
t A
be
rafa
n B
ea
ch d
uri
ng
we
t w
ea
the
r.
Lag
oo
n d
esi
gn
als
o a
sse
sse
d a
s h
av
ing
a s
ign
ific
an
tly
hig
he
r
en
vir
on
me
nta
l, e
colo
gic
al,
vis
ua
l a
nd
na
vig
ati
on
im
pa
ct –
co
nce
rns
rais
ed
by
mu
ltip
le s
tak
eh
old
ers
.
Iso
late
d e
ast
ern
la
nd
fall
th
rea
ten
s m
ast
erp
lan
nin
g a
nd
recr
ea
tio
na
l a
mb
itio
ns.
Op
tio
n r
eje
cte
d.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
12
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n J
. G
oo
d w
all
to
are
a r
ati
o,
go
od
po
ten
tia
l
en
erg
y o
utp
ut.
Av
oid
s e
ncr
oa
chm
en
t o
nto
SS
SI
an
d
Ne
ath
Ch
an
ne
l. B
oth
wa
lls
loca
ted
10
0m
fro
m
dre
dg
ed
riv
er
cha
nn
els
. W
all
de
pth
re
aso
na
ble
so
cap
ita
l co
sts
acc
ep
tab
le.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.1
8
Hig
h l
ev
el
coa
sta
l p
roce
ss m
od
ell
ing
ca
rrie
d o
ut
on
th
is o
pti
on
to
ass
ess
im
pa
ct o
f la
go
on
de
sig
ns
avo
idin
g t
he
SS
SI.
Th
e r
esu
lts
ind
ica
ted
re
du
ced
po
ten
tia
l im
pa
cts
on
co
ast
al
pro
cess
es
com
pa
red
wit
h o
pti
on
s w
hic
h c
ross
in
to t
he
SS
SI
(re
pre
sen
ted
by
op
tio
n K
) o
r e
nco
mp
ass
th
e S
SS
I (r
ep
rese
nte
d b
y o
pti
on
L).
No
en
cro
ach
me
nt
on
to S
SS
I a
nd
la
go
on
wa
ll s
et
ba
ck 1
00
m f
rom
Ne
ath
Ch
an
ne
l.
Po
ten
tia
l sy
ne
rgie
s a
nd
de
sig
n o
pp
ort
un
itie
s cr
ea
ted
wit
h n
ew
Sw
an
sea
Un
ive
rsit
y B
ay
Ca
mp
us
(SU
BC
) a
t e
ast
ern
la
nd
fall
.
Wa
ter
qu
ali
ty m
od
ell
ing
als
o d
em
on
stra
ted
no
ad
ve
rse
im
pa
ct o
n
Ab
era
fan
Be
ach
fro
m t
he
Riv
er
Ne
ath
.
Info
rma
l d
iscu
ssio
ns
wit
h N
PA
an
d C
CW
/EA
in
dic
ate
d t
his
de
sig
n
wa
s vi
ew
ed
as
a g
oo
d c
om
pro
mis
e l
ay
ou
t, f
all
ing
be
twe
en
de
sig
n
D a
nd
la
rge
r o
pti
on
s F
, H
, I,
K,
L a
nd
M.
Op
tio
n t
ak
en
fo
rwa
rd f
or
refi
ne
me
nt
– s
ee
J1
th
rou
gh
to
J3
be
low
.
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n K
. V
ari
ati
on
of
Op
tio
n J
, e
xte
nd
ed
ea
stw
ard
s
to i
ncr
ea
se e
ne
rgy
ou
tpu
t, c
ross
ing
th
e S
SS
I a
nd
req
uir
ing
re
-ali
gn
me
nt
of
Ne
ath
dre
dg
ed
ch
an
ne
l.
En
erg
y m
od
ell
ing
an
d c
ost
mo
de
llin
g v
ery
po
siti
ve
:
ind
ee
d,
this
wa
s T
LSB
’s p
refe
rre
d l
ag
oo
n d
esi
gn
fro
m a
va
lue
fo
r m
on
ey
an
d e
ng
ine
eri
ng
pe
rsp
ect
ive
.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.3
4
Hig
h l
ev
el
coa
sta
l p
roce
ss m
od
ell
ing
wa
s ca
rrie
d o
ut
on
th
is o
pti
on
to a
sse
ss i
mp
act
of
lag
oo
n d
esi
gn
s e
ncr
oa
chin
g i
nto
th
e C
rym
lyn
Bu
rro
ws
SS
SI.
Re
sult
s sh
ow
ed
th
is o
pti
on
ha
s h
igh
er
po
ten
tia
l
coa
sta
l p
roce
ss i
mp
act
s co
mp
are
d t
o O
pti
on
J.
Op
tio
n a
lso
aff
ect
ed
th
e a
lig
nm
en
t o
f th
e N
ea
th c
ha
nn
el
an
d a
s su
ch w
ate
r
qu
ali
ty a
t A
be
rafa
n w
ou
ld b
e a
t g
rea
ter
risk
du
rin
g w
et
we
ath
er.
Co
nce
rns
rais
ed
by
mu
ltip
le s
tak
eh
old
ers
.
Op
tio
n r
eje
cte
d.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
13
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n L
. E
xtre
me
va
ria
tio
n o
f d
esi
gn
J,
ext
en
de
d
ea
stw
ard
s to
in
cre
ase
en
erg
y o
utp
ut,
en
com
pa
ssin
g
the
SS
SI
an
d r
eq
uir
ing
re
-ali
gn
me
nt
of
Ne
ath
dre
dg
ed
ch
an
ne
l. E
ne
rgy
mo
de
llin
g a
nd
co
st
mo
de
llin
g p
osi
tiv
e.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.5
1
Hig
h l
ev
el
coa
sta
l p
roce
ss m
od
ell
ing
ca
rrie
d o
ut
on
th
is o
pti
on
to
ass
ess
im
pa
ct o
f la
go
on
de
sig
ns
en
com
pa
ssin
g t
he
SS
SI.
Th
is
op
tio
n w
ou
ld a
lso
re
qu
ire
th
e r
ea
lig
nm
en
t o
f th
e N
ea
th C
ha
nn
el.
Op
tio
n w
as
reje
cte
d d
ue
to
po
ten
tia
l w
ate
r q
ua
lity
eff
ect
on
ne
arb
y A
be
rafa
n a
nd
co
ast
al
pro
cess
eff
ect
s o
n C
rym
lyn
Bu
rro
ws
SS
SI.
Co
nce
rns
rais
ed
by
mu
ltip
le s
tak
eh
old
ers
.
Op
tio
n r
eje
cte
d.
Jan
ua
ry –
Ju
ne
20
13
Op
tio
n M
. F
urt
he
r v
ari
ati
on
of
Op
tio
n J
, e
xte
nd
ed
ea
stw
ard
s w
ith
ou
t e
ncr
oa
chin
g o
n t
he
SS
SI
an
d
red
uci
ng
ch
an
ge
re
qu
ire
d t
o N
ea
th d
red
ge
d c
ha
nn
el.
En
erg
y m
od
ell
ing
an
d c
ost
mo
de
llin
g v
ery
po
siti
ve
.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.3
1
NP
A o
bje
cte
d d
ue
to
an
tici
pa
ted
pro
ble
ms
for
pil
ots
ap
pro
ach
ing
the
Ne
ath
Ch
an
ne
l. O
pti
on
re
ject
ed
as
ad
dit
ion
al
imp
act
s in
te
rms
of
wa
ter
qu
ali
ty a
nd
co
ast
al
pro
cess
es
ou
twe
igh
ed
th
e b
en
efi
t o
f
incr
ea
sed
ge
ne
rati
on
ca
pa
city
.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
14
Re
fin
em
en
t o
f la
go
on
de
sig
n J
– J
un
e 2
01
3
Op
tio
n J
1 w
as
slig
htl
y e
nla
rge
d (
com
pa
red
to
Op
tio
n
J) i
n o
rde
r to
in
corp
ora
te t
rain
ing
wa
lls
for
the
Ne
ath
Ch
an
ne
l, a
lso
to
giv
e a
n i
mp
rov
ed
wa
ll t
o a
rea
ra
tio
an
d g
rea
ter
po
ten
tia
l e
ne
rgy
ou
tpu
t.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.2
8
Re
ject
ed
fo
llo
win
g f
urt
he
r co
nsu
lta
tio
n w
ith
NP
A a
bo
ut
cro
ssin
g o
f
tra
inin
g w
all
s to
Ne
ath
Ch
an
ne
l a
nd
be
cau
se t
he
op
tio
n r
eq
uir
ed
a
cha
ng
e i
n a
lig
nm
en
t to
th
e N
ea
th C
ha
nn
el.
Op
tio
n J
2.
Po
siti
on
ed
th
e e
ast
ern
la
go
on
wa
ll 1
00
m
fro
m t
he
Ne
ath
ch
an
ne
l a
nd
mo
ve
d t
he
tu
rbin
e
ho
usi
ng
in
to s
ha
llo
we
r w
ate
r to
re
du
ce c
on
stru
ctio
n
cost
. T
he
we
ste
rn l
ag
oo
n l
an
dfa
ll w
as
lin
ke
d i
nto
th
e
exi
stin
g T
aw
e e
ast
ern
ap
pro
ach
wa
ll t
o
rem
ov
e/r
ep
lace
de
reli
ct i
nfr
ast
ruct
ure
an
d t
he
reb
y
imp
rov
e v
isu
al
ap
pe
ara
nce
fro
m l
an
d.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.1
9
NP
A r
eq
ue
ste
d:
a)
relo
cati
on
of
ea
ste
rn l
ag
oo
n s
ea
wa
ll t
o f
orm
th
e w
est
ern
tra
inin
g w
all
of
the
dre
dg
ed
ch
an
ne
l
b)
wid
en
ing
of
the
ea
ste
rn w
all
of
the
ap
pro
ach
to
th
e N
ea
th
cha
nn
el
Fu
rth
er
dis
cuss
ion
s w
ith
NP
A a
llo
we
d f
ina
l a
dju
stm
en
ts t
o
inco
rpo
rate
th
e t
rain
ing
wa
ll i
nto
th
e d
esi
gn
of
the
ch
an
ne
l. T
he
resu
lt w
as
op
tio
n J
3.
Op
tio
n J
3.
Re
fin
em
en
t o
f d
esi
gn
J t
o i
nco
rpo
rate
all
imp
rov
em
en
ts i
de
nti
fie
d a
bo
ve
, a
nd
est
ab
lish
an
ap
pro
pri
ate
co
mp
rom
ise
de
sig
n,
ba
lan
cin
g
en
vir
on
me
nta
l a
nd
na
vig
ati
on
al
imp
act
wit
h
tech
nic
al
req
uir
em
en
ts a
nd
re
spo
nd
ing
to
sta
ke
ho
lde
r co
mm
en
ts.
Ra
tio
of
sea
wa
ll t
o e
ncl
ose
d a
rea
– 1
:1.2
1
Ide
nti
fie
d a
s P
refe
rre
d O
pti
on
fo
r fo
rma
l co
nsu
lta
tio
n a
nd
refe
ren
ce d
esi
gn
fo
r E
IA p
urp
ose
s.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
15
CO
NS
ULT
AT
ION
PH
AS
E:
Sta
tuto
ry s
42
an
d s
47
– P
refe
rre
d O
pti
on
an
d t
he
PE
IR,
July
20
13
on
wa
rds
T
LSB
en
gin
ee
rs i
nv
est
iga
ted
re
qu
ire
me
nts
fo
r th
e h
eig
ht
of
the
se
aw
all
s in
pa
rall
el
wit
h t
he
ab
ov
e w
ork
on
la
go
on
siz
e a
nd
la
yo
ut.
Wa
ve
da
ta i
nd
ica
ted
th
at
the
init
ial
ide
nti
fie
d r
eq
uir
em
en
t (O
pti
on
D)
for
a s
ea
wa
ll o
f 1
1-1
9m
(2
.8m
ab
ov
e h
igh
wa
ter
an
d 1
1.3
m a
bo
ve
lo
w w
ate
r) w
as
inco
rre
ct.
Clo
se t
o s
ho
re,
the
se
aw
all
cou
ld b
e l
ow
er,
bu
t o
ffsh
ore
mo
re h
eig
ht
wa
s re
qu
ire
d f
or
stru
ctu
ral
inte
gri
ty a
nd
op
era
tio
na
l/v
isit
or
safe
ty,
wit
h a
ne
w r
an
ge
id
en
tifi
ed
fo
r la
go
on
op
tio
n J
3 a
s:
5-2
0m
(3
.5m
ab
ov
e h
igh
wa
ter,
an
d 1
2m
ab
ov
e l
ow
wa
ter)
.
Wa
ll l
en
gth
9.5
km
Are
a
11
.7km
2
Ra
ted
ca
pa
city
(@
4.5
m h
ea
d)
2
40
MW
An
nu
al
ou
tpu
t (g
ross
)
40
0G
Wh
De
sig
n l
ife
up
to
12
0y
rs
He
igh
t o
f w
all
5-2
0m
Wa
ll a
bo
ve
lo
w w
ate
r
12
m
Wa
ll a
bo
ve
hig
h w
ate
r
3.5
m
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 16
Figure 3.2 Key difference between Lagoon layout options J(3) and J(2)1
3.5 Turbines and sluice gates
3.5.1 Introduction
3.5.1.1 In order to optimise output from a tidal range power project there are a number of
factors to consider, including:
a) type of turbine (single or bi-directional flow);
b) the size and number of turbines; and
c) the number of sluice gates.
3.5.1.2 An overview of the selection of these elements of the Project is presented in the sections
below.
1 The options for lagoon design in respect of the location of turbine and sluice gate housing that are comprised
within the Project are presented in Section 4.3.3 of Chapter 4, Project Description.
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 17
3.5.2 Turbines
Single (ebb tide) or dual generation (ebb and flood tide)
3.5.2.1 Low head bulb turbines have been used for the generation of electricity in river and dam
projects for well over 50 years. As such, they are a tried and tested technology. For the
purpose of the Project, a variety of existing conventional hydro technologies were
investigated further during the preliminary stage.
3.5.2.2 Options considered at an early stage looked at whether the Project would only generate
on the ebb tide, or whether the Project could generate on both the ebb and flood tides
(dual generation).
3.5.2.3 Early energy modelling suggested the maximum achievable output from ebb-only
generation would be approximately 25% of the lagoon impoundment’s potential energy.
However, in order to make lagoons commercially viable, approximately 35% of the
potential energy output is necessary. To achieve this, dual generation (on ebb and flood
tide) is essential.
3.5.2.4 The energy outputs for a number of dual design turbines were very positive showing
greater than 40% of the potential energy output was possible. Further engineering
design, and understanding of lagoon operations from the turbine manufacturers, along
with reliable performance data, all pointed towards bi-directional turbines being the
optimum solution for the Project.
3.5.2.5 The type of turbine to be used for the Project has been narrowed down, following
detailed engineering input from the major turbine manufacturers. The preferred options
are either: a slightly modified bi-directional double regulated bulb turbine; or a bi-
directional variable speed bulb turbine. Ongoing detailed technical and commercial
evaluation of both turbines is currently being undertaken to establish the best possible
option for the Project. Further information on turbines is presented in Chapter 4, Project
Description and the principle of the "Rochdale envelope", which has been applied to the
EIA process, assesses the likely “worst case scenario” impacts for the use of either of
these technologies in the relevant chapters of the ES.
Size and number of turbines
3.5.2.6 Energy modelling undertaken for the Project has focussed on the relationship between
turbine diameter, discharge rate, power output, and the number of units. In this way the
optimum size and number of turbines needed can be established.
3.5.2.7 Initial energy modelling looked at 2m and 3.3m units, as these were the largest unit size
that could be installed with floating caissons and without bed excavation. However, once
an "in-situ" turbine housing construction method was selected, larger turbine options
could be considered. Using in-situ construction, with localised excavation, larger turbines
6m or 7m in diameter could be considered. These larger turbines are preferable as fewer
units are needed, which is advantageous in terms of cost, manufacturing and installation
lead times. Larger units generally have a slower rotational speed and higher flow rate
and are therefore potentially less harmful to fish and other marine species when
compared to smaller units.
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 18
3.5.2.8 Energy modelling has been undertaken to determine the optimum number of larger
diameter turbines for the Project. The preferred design is presented in Chapter 4, Project
Description.
3.5.3 Sluice gates
Number of sluice gates
3.5.3.1 Energy modelling shows that, in order to optimise electricity generation on each tidal
cycle, the water level in the lagoon must return to as close to the water mark outside the
lagoon as possible. In this way, the maximum head on the following tide is maintained.
This balancing of water level and power generation is achieved by flow through the
turbines and flow through the sluice gates.
3.5.3.2 The outputs for different combinations of turbines and sluice gates, and the sluice flows
required have been modelled. Larger sluicing capacity gives higher energy outputs and
more closely follows the natural tide in terms of foreshore exposure within the lagoon.
3.5.3.3 In bi-directional mode, sluicing (on the ebb and flood tide) at the end of the generation
sequence allows an increase in head and thus more power from the next tide.
Type of sluice gates
3.5.3.4 Other projects, for instance the studies relating to the Severn Barrage, have considered
numerous sluice gate designs. These were reviewed and it was decided to keep the
Project’s sluice gates as simple and robust as possible, with local fabrication being
preferable.
3.5.3.5 Most of the standard gate designs were not suitable for bi-directional flow, so vertical lift
roller gates have been selected. This is a simple, robust gate design, which is well proven
in marine use. The proposed gates chosen have a large discharge capacity, are based on
mature technology, are easy to maintain, and are capable of being manufactured locally.
Size of sluice gates
3.5.3.6 The larger the discharge capacity through sluice gates, the better in terms of energy
production. However, there is a trade-off against an optimum point for size, cost and
practicality of logistics and supply chain.
3.5.3.7 The sluice gate design has been obtained by examining the discharge capacity, cost and
logistical practicality. The sluice gates can be easily fabricated in Wales by a number of
companies and can be transported using standard low loaders and cranes.
3.6 Construction method choices
3.6.1 Turbine-housing construction
3.6.1.1 The turbine housing had two options for construction: a floating caisson; or an in-situ
cofferdam technique.
3.6.1.2 The initial designs focussed only on floating caissons, as a marine cofferdam was viewed
as too costly. It was also assumed that submerged excavation would be technically
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 19
challenging, and so turbine size with a maximum diameter of 3.3m was assumed to avoid
any need for excavation.
3.6.1.3 Later, with the involvement of a main civil engineering contractor, a more detailed cost
and risk analysis was conducted, looking at various dry dock caisson options and
cofferdam options including sand bund, Geotubes® and steel cellular cofferdam.
3.6.1.4 In-situ cofferdam construction is now the preferred option so that construction can take
place in dry conditions. This is better in terms of cost, reduced weather risk, ease of bed
preparation, access for equipment and larger sizes of turbines.
3.6.1.5 Further information is provided below on all the in-situ cofferdam construction options
which have been considered during the Project development. For those not progressed,
reasons are provided. Chapter 4, Project Description gives additional details of the
cofferdam designs which are being taken forward and have been assessed in the EIA.
3.6.2 Offshore temporary bund
3.6.2.1 Once the method of turbine-housing construction had been decided as being built in-situ
within a dry cofferdam, two approaches were analysed: a ‘soft’ option, using sediment as
the main material; and a ‘hard’ option, using steel piles.
3.6.2.2 Each of the options has been progressed to a stage where the relative cost, duration,
risk, buildability, and other impacts could be compared.
3.6.3 Soft options
3.6.3.1 Initially 3 ‘soft’ options of sand bund were considered, the first being made entirely of
sand/sediment pumped into position by the dredging equipment. The second option was
to create the bund with Geotubes® and a sediment core in a similar way to the
permanent seawalls, but without the rock armour protection. The third option was to
replicate the permanent lagoon seawall design, by creating a bund with Geotubes®, a
sediment core and rock armour protection of the sea side of the bund.
3.6.3.2 The first option was rejected due to the large quantity of sand/sediment required and
the vulnerability of a purely sand/sediment bund to sea conditions.
3.6.3.3 The second option was rejected due to vulnerability of the Geotubes® without any rock
armour protection, as the temporary bund would need to be in place for over a year.
3.6.3.4 The third option, which is based on the main seawall design, remains an alternative
under active consideration and further details are provided in Chapter 4.
3.6.4 Hard options
3.6.4.1 Two ‘hard’ options were originally considered: a circular sheet-piled cofferdam; and a
twin sheet-piled cofferdam.
3.6.4.2 The circular sheet-piled cofferdam would be fabricated onshore by installing sheet piles
around a prefabricated steel frame. A jack-up barge, loaded with a crawler crane, would
then be floated into position along with a crane vessel to lift and accurately position the
cells. Once the sheet-pile cell is in place, resting on the sea bed, the crawler crane would
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 20
vibrate the sheet-pile into the seabed to ensure that it stays in the correct place. This
process would be repeated until the cofferdam is formed. The cells would be filled with
sediment and a working platform/access road created on the top. This option was
rejected due to the difficulty in removing the piles for re-use or resale, thereby
significantly increasing the cost of the option.
3.6.4.3 The twin sheet-piled cofferdam remains an alternative under active consideration and
further details are found in Chapter 4, Project Description.
3.7 Grid connection
3.7.0.1 During the development of the Project, the grid connection was also a key consideration
and this has evolved significantly over the last two years. Some factors which have
influenced the grid connection include:
a. The generation capacity of the Project and the proximity of a suitable substation
connection point;
b. The presence of a landfall to minimise marine works; and
c. Options to minimise impacts on the surrounding environment through use of
existing brownfield/linear development routes versus previously undeveloped land.
3.7.0.2 With regard to the latter point, both greenfield and brownfield routes have their own
advantages and disadvantages. For instance, use of brownfield or linear routes such as
roads or footpaths would have the potential to minimise impacts on ecology. However,
previously developed land would have the potential for contamination or the presence
of existing services which would inhibit or restrict its use.
3.7.0.3 The following table summarises some of the key stages of the grid connection
development:
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
21
Ta
ble
3.2
K
ey
sta
ge
s o
f th
e g
rid
co
nn
ect
ion
de
ve
lop
me
nt
LAG
OO
N D
ES
IGN
D
ES
IGN
DA
TE
& R
AT
ION
ALE
E
IA F
EE
DB
AC
K &
DE
CIS
ION
Ea
rly
pro
ject
de
fin
itio
n
Wit
h t
he
ori
gin
al
lag
oo
n d
esi
gn
s o
f le
ss t
ha
n 1
00
MW
a l
oca
l g
rid
co
nn
ect
ion
po
int
to t
he
no
rth
of
Sw
an
sea
Po
rt w
as
ide
nti
fie
d a
t T
ir J
oh
n.
In
te
rms
of
the
“o
ffsh
ore
” la
go
on
de
sig
n,
the
mo
st d
ire
ct c
ab
le
rou
te f
rom
th
e l
ag
oo
n t
o t
he
co
ast
wa
s ch
ose
n t
o
min
imis
e t
he
ext
en
t o
f m
ari
ne
ca
ble
. T
he
ca
ble
ro
ute
the
n f
oll
ow
ed
exi
stin
g p
ort
ro
ad
in
fra
stru
ctu
re o
r
cro
sse
d b
row
nfi
eld
la
nd
to
he
ad
no
rth
to
Tir
Jo
hn
.
Th
is m
ost
dir
ect
ro
ute
no
rth
wo
uld
re
qu
ire
th
e n
ee
d
to c
ross
ra
ilw
ay
lin
es
an
d F
ab
ian
Wa
y (
A4
83
).
Th
e m
ost
dir
ect
ro
ute
no
rth
fro
m t
he
po
rt w
as
reje
cte
d d
ue
to
iss
ue
s a
sso
cia
ted
wit
h t
he
cro
ssin
g
of
the
ma
in r
ail
wa
y l
ine
an
d F
ab
ian
Wa
y.
Wit
h t
he
de
ve
lop
me
nt
of
the
la
nd
co
nn
ect
ed
lag
oo
ns
(op
tio
ns
B –
C,
Ta
ble
3.1
) th
e n
ee
d f
or
exp
en
siv
e m
ari
ne
ca
ble
wa
s n
eg
ate
d a
nd
th
e c
ab
le
wa
s to
be
la
id w
ith
in t
he
la
go
on
se
aw
all
.
Th
e T
ir J
oh
n s
ub
sta
tio
n c
on
ne
ctio
n p
oin
t co
nti
nu
ed
to b
e c
on
sid
ere
d f
or
the
“sm
all
er”
la
go
on
s
(<1
00
MW
).
Alt
ern
ati
ve
le
ss d
ire
ct r
ou
tes
to T
ir J
oh
n
we
re i
nv
est
iga
ted
to
fin
d a
lte
rna
tiv
e m
ea
ns
of
cro
ssin
g t
he
ra
ilw
ay
lin
e a
nd
Fa
bia
n W
ay
.
Wit
h t
he
in
cre
ase
in
ge
ne
rati
on
ca
pa
city
of
lag
oo
n
(>1
00
MW
) co
nn
ect
ion
to
Tir
Jo
hn
wa
s n
o l
on
ge
r
ap
pro
pri
ate
an
d a
co
nn
ect
ion
to
Na
tio
na
l G
rid
's
Ba
gla
n B
ay
Su
bst
ati
on
wa
s re
qu
ire
d.
Init
iall
y,
two
la
nd
ba
sed
ro
ute
s w
ere
lo
ok
ed
at
on
e
uti
lisi
ng
th
e e
ast
ern
la
nd
fall
to
th
e P
ort
, a
nd
eit
he
r
the
M4
ro
ad
bri
dg
e c
ross
ing
of
the
riv
er
Ne
ath
(R
ed
)
or
dir
ect
ion
al
dri
llin
g b
en
ea
th t
he
riv
er
(gre
en
).
In
ad
dit
ion
a m
ore
dir
ect
ma
rin
e o
pti
on
wa
s a
lso
con
sid
ere
d (
ye
llo
w).
Th
e m
ari
ne
ca
ble
ro
ute
op
tio
n w
as
reje
cte
d d
ue
to a
nu
mb
er
of
fact
ors
in
clu
din
g:
the
hig
h c
ost
s
ass
oci
ate
d w
ith
un
de
rwa
ter
cab
les
an
d i
ssu
es
wit
h m
ain
tain
ing
ap
pro
pri
ate
bu
ria
l d
ep
th f
or
cro
ssin
g t
he
Ne
ath
wh
ilst
sti
ll a
llo
win
g f
or
ma
inte
na
nce
dre
dg
ing
of
the
ch
an
ne
l.
Th
e r
ed
ro
ute
wa
s su
bm
itte
d w
ith
th
e s
cop
ing
do
cum
en
t in
Oct
ob
er
20
12
. In
te
rms
of
the
la
nd
ba
sed
ro
ute
s, w
ith
th
e c
ha
ng
e i
n t
he
ea
ste
rn
lan
dfa
ll f
rom
th
e p
ort
to
fu
rth
er
ea
st,
the
se
op
tio
ns
we
re n
o l
on
ge
r v
iab
le a
nd
fu
rth
er
inv
est
iga
tio
n w
as
un
de
rta
ke
n.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
22
LAT
ER
PR
OJE
CT
DE
FIN
ITIO
N
CA
BLE
RO
UT
E
CO
NS
TR
AIN
TS
SU
MM
AR
Y
All
ca
ble
ro
ute
op
tio
ns
Su
bse
qu
en
t to
fe
ed
ba
ck o
n t
he
sco
pin
g d
ocu
me
nt
an
d a
dva
nce
me
nt
in t
he
la
go
on
de
sig
n,
the
ca
ble
ro
ute
ite
rati
on
pro
cess
ha
s b
ee
n f
urt
he
r p
rog
ress
ed
. S
ince
Ja
nu
ary
20
13
, th
is h
as
incl
ud
ed
th
e e
xam
ina
tio
n o
f se
ve
ral
rou
te o
pti
on
s a
lon
g d
iffe
ren
t
sect
ion
s o
f th
e o
ve
rall
ro
ute
to
Ba
gla
n B
ay
Su
bst
ati
on
. K
ey
co
nst
rain
ts a
pp
lyin
g t
o t
he
va
rio
us
sect
ion
s a
re d
iscu
sse
d b
elo
w.
CA
BLE
RO
UT
E
DE
SIG
N D
AT
E &
RO
UT
E
CO
NS
TR
AIN
TS
/CO
MM
EN
TS
Jan
ua
ry 2
01
3 t
o J
uly
20
13
Jan
ua
ry 2
01
3 –
Ju
ly 2
01
3
Ca
ble
ro
ute
fro
m t
he
tu
rbin
e h
ou
se t
o t
he
Ba
gla
n
Ba
y s
ub
sta
tio
n,
foll
ow
ing
th
e w
est
ern
bre
ak
wa
ter,
an
d f
rom
th
e b
rea
kw
ate
r la
nd
ing
po
int
thro
ug
h t
he
Po
rt o
f S
wa
nse
a l
an
d.
Aft
er
Ba
ldw
in’s
cre
sce
nt,
th
e r
ou
te e
nte
rs t
he
ve
rge
ne
xt t
o F
ab
ian
Wa
y (
A4
83
).
Be
fore
th
e
rou
nd
ab
ou
t (e
ast
ern
sid
e o
f th
e S
SS
I),
the
ro
ute
div
erg
es
into
th
e S
SS
I to
fo
llo
w t
he
exi
stin
g p
ath
to a
va
lve
pit
ass
oci
ate
d w
ith
exi
stin
g p
ipe
s/d
uct
s
pri
or
to c
ross
ing
th
e R
ive
r N
ea
th.
Th
e r
ou
te
wo
uld
use
th
e e
xist
ing
du
cts
to c
ross
th
e r
ive
r o
r
a d
ire
ctio
na
l d
rill
wo
uld
be
un
de
rta
ke
n b
efo
re
foll
ow
ing
th
e e
xist
ing
pa
th o
n l
an
d t
o t
he
Ba
gla
n
Ba
y s
ub
sta
tio
n.
Ap
pro
xim
ate
ro
ute
le
ng
th:
10
km
Th
is r
ou
te w
as
pre
sen
ted
in
th
e P
EIR
. It
wa
s b
ase
d o
n i
nit
ial
OS
ma
ps
an
d f
urt
he
r st
atu
tory
un
de
rta
ke
r se
arc
h i
s re
qu
ire
d t
o
pro
gre
ss a
na
lysi
s o
f th
e r
ou
te.
Init
iall
y,
this
ro
ute
se
em
ed
to
be
fa
irly
cle
ar
of
ob
stru
ctio
ns
an
d
issu
es.
If
pro
gre
sse
d,
top
og
rap
hic
su
rve
y w
ou
ld b
e r
eq
uir
ed
to
ass
ess
th
e l
ev
els
of
ve
ge
tati
on
alo
ng
sid
e F
ab
ian
Wa
y a
nd
oth
er
pa
rts
of
the
ro
ute
, to
se
e i
f th
is w
ou
ld a
ffe
ct t
he
pla
nn
ed
ca
ble
rou
te.
At
this
sta
ge
no
in
form
ati
on
wa
s a
vail
ab
le r
eg
ard
ing
th
e p
rop
ose
d
Sw
an
sea
Un
ive
rsit
y B
ay
Ca
mp
us
(SU
BC
- p
rev
iou
sly
kn
ow
n a
s th
e
Sci
en
ce a
nd
In
no
vati
on
Ca
mp
us)
.
Op
tio
n t
o b
e t
ak
en
fo
rwa
rd.
Fu
rth
er
info
rma
tio
n t
o b
e o
bta
ine
d
for
vari
ou
s k
ey
se
ctio
ns
an
d r
efi
ne
me
nt
to b
e u
nd
ert
ak
en
foll
ow
ing
in
form
ati
on
re
vie
w.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
23
July
– A
ug
ust
20
13
Ca
ble
ro
ute
as
pre
vio
us,
bu
t w
ith
an
op
tio
na
l ro
ute
div
erg
ing
in
to t
he
SS
SI
to f
oll
ow
th
e e
xist
ing
pa
th.
We
ste
rn a
rm r
ou
te,
wit
h o
pti
on
al
rou
te t
hro
ug
h S
SS
I
(se
e p
ictu
re,
left
- o
ran
ge
in
dic
ate
s th
e o
pti
on
al
rou
te).
Aft
er
a s
tatu
tory
un
de
rta
ke
r se
arc
h w
as
com
ple
ted
th
e o
rig
ina
l
cab
le r
ou
te w
as
alt
ere
d s
lig
htl
y t
o e
nsu
re t
ha
t cr
oss
ing
s o
f e
xist
ing
serv
ice
s w
ere
min
imis
ed
wh
ere
po
ssib
le.
Th
e o
pti
on
al
SS
SI
rou
te w
as
intr
od
uce
d a
s it
wa
s u
ncl
ea
r w
he
the
r
the
Fa
bia
n W
ay
ve
rge
na
rro
we
d p
ara
lle
l to
th
e S
SS
I zo
ne
. N
PT
CB
C
als
o a
dv
ise
d t
ha
t F
ab
ian
Wa
y v
erg
e i
s a
co
nse
rva
tio
n v
erg
e a
nd
is
ma
na
ge
d a
s a
ha
y m
ea
do
w.
As
such
pla
ns
to m
inim
ise
im
pa
ct
sho
uld
be
co
nsi
de
red
wh
ere
po
ssib
le (
Ch
ap
ter
12
, T
err
est
ria
l
Eco
log
y).
T
he
op
tio
n t
o u
se p
ath
s in
th
e S
SS
I w
ou
ld m
inim
ise
th
e
imp
act
on
th
e v
erg
e,
wh
ilst
als
o a
void
ing
en
teri
ng
th
e S
UB
C l
an
d.
Th
e S
SS
I ro
ute
pa
sse
d t
hro
ug
h p
atc
he
s o
f v
eg
eta
tio
n w
ith
in t
he
SS
SI,
wh
ich
ma
y b
e e
nv
iro
nm
en
tall
y s
en
siti
ve
, th
ere
fore
po
sin
g
po
ten
tia
l is
sue
s fo
r th
is c
ab
le r
ou
te.
No
twit
hst
an
din
g t
his
wit
h
care
ful
con
sid
era
tio
n t
his
ro
ute
co
uld
sti
ll b
e f
ea
sib
le.
Bo
th o
pti
on
s (F
ab
ian
Wa
y v
erg
e a
nd
SS
SI)
re
ma
in a
lte
rna
tiv
es
un
de
r a
ctiv
e c
on
sid
era
tio
n.
Se
pte
mb
er
– O
cto
be
r 2
01
3
An
alt
ern
ati
ve
dir
ect
ion
al
dri
llin
g l
oca
tio
n w
as
pro
po
sed
fo
r th
e R
ive
r N
ea
th c
ross
ing
sh
ou
ld t
he
exi
stin
g d
uct
s b
e u
nsu
ita
ble
fo
r th
e c
ab
le r
ou
te.
Pre
vio
usl
y i
t w
as
pro
po
sed
to
cro
ss a
dja
cen
t to
th
e
du
cts
(se
e p
ictu
re,
gre
en
in
dic
ate
s o
ld r
ou
te a
nd
ye
llo
w i
nd
ica
tes
the
ne
w d
ire
ctio
na
l d
rill
ing
ro
ute
).
Th
e p
ath
of
the
ne
w d
ire
ctio
na
l d
rill
ing
wa
s se
lect
ed
to
ru
n f
rom
the
va
lve
pit
dia
go
na
lly
acr
oss
th
e R
ive
r N
ea
th t
o m
inim
ise
th
e
imp
act
s o
n t
he
SS
SI.
N
ote
, th
is o
pti
on
is
mo
re e
xpe
nsi
ve
th
an
reu
sin
g t
he
exi
stin
g d
uct
s.
Ho
we
ve
r, a
la
ck o
f in
form
ati
on
re
ga
rdin
g t
he
exi
stin
g d
uct
s a
nd
the
ir s
uit
ab
ilit
y f
or
reu
se m
ea
ns
tha
t a
lte
rna
tiv
e o
pti
on
s to
cro
ss
the
Ne
ath
ne
ed
s to
be
re
tain
ed
.
Op
tio
n o
f u
sin
g n
ew
HD
D i
s co
nsi
de
red
if
the
exi
stin
g d
uct
s a
re
pro
ve
n u
nsu
ita
ble
.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
24
Clo
se u
p o
f e
nd
of
rou
te
Ov
erv
iew
of
rou
tes
Au
gu
st –
Se
pte
mb
er
20
13
Ca
ble
ro
ute
as
pre
vio
us
(Ju
ly/A
ug
ust
), b
ut
wit
h
ext
en
de
d r
ou
te o
pti
on
s th
rou
gh
th
e S
SS
I.
Th
e
Fa
bia
n W
ay
ro
ute
wa
s e
xte
nd
ed
to
co
nti
nu
e p
ast
the
ro
un
da
bo
ut
(po
int
2)
an
d e
nte
r th
e S
SS
I e
ast
of
the
go
lf c
ou
rse
. R
ou
te o
pti
on
s p
rio
r to
th
e v
alv
e p
it
(3)
ma
de
use
of
ne
w d
ire
ctio
na
l d
rill
ing
to
cro
ss t
he
Riv
er
Ne
ath
.
We
ste
rn a
rm r
ou
te,
mu
ltip
le S
SS
I o
pti
on
s (s
ee
pic
ture
, le
ft.
Op
tio
ns:
re
d r
ou
te –
fo
llo
win
g F
ab
ian
wa
y u
p t
o t
he
go
lf c
ou
rse
wit
h n
ew
ho
rizo
nta
l
dir
ect
ion
al
dri
llin
g (
HD
D)
at
po
int
5,
ye
llo
w r
ou
te –
foll
ow
ing
th
e p
ath
th
rou
gh
th
e S
SS
I zo
ne
an
d r
eu
sin
g
exi
stin
g d
uct
cro
ssin
g (
po
int
3),
blu
e r
ou
te –
ne
w
HD
D f
rom
th
e y
ell
ow
ro
ute
(p
oin
t 3
), o
ran
ge
ro
ute
–
foll
ow
ing
th
e p
ath
th
rou
gh
th
e S
SS
I a
nd
jo
inin
g r
ed
HD
D,
gre
en
ro
ute
– n
ew
HD
D f
rom
ora
ng
e r
ou
te).
Th
e m
ult
iple
ro
ute
op
tio
ns
thro
ug
h t
he
SS
SI
we
re p
rop
ose
d i
n
ord
er
to c
on
sid
er
the
ro
ute
wit
h t
he
le
ast
en
vir
on
me
nta
l im
pa
ct
on
th
e S
SS
I.
Th
e a
dva
nta
ge
s a
nd
dis
ad
va
nta
ge
s o
f e
ach
ro
ute
are
as
foll
ow
s:
Re
d r
ou
te –
Ad
van
tag
e:
Sh
ort
est
HD
D (
35
0m
) a
vo
ids
SS
SI
an
d
the
refo
re t
he
re a
re p
ote
nti
all
y l
ess
en
vir
on
me
nta
l re
stri
ctio
ns.
Dis
ad
van
tag
e:
Th
e s
ou
the
rn v
erg
e o
f F
ab
ian
Wa
y i
s a
co
nse
rva
tio
n
ve
rge
an
d i
t a
lso
ha
s e
xist
ing
uti
liti
es
pre
sen
t.
Ye
llo
w r
ou
te –
Ad
va
nta
ge
: W
ell
est
ab
lish
ed
tra
ck w
ith
in t
he
SS
SI,
min
ima
l sh
rub
cle
ara
nce
to
ge
t p
lan
t e
qu
ipm
en
t th
rou
gh
, n
o H
DD
req
uir
ed
if
acc
ess
to
exi
stin
g d
uct
s u
nd
er
the
riv
er
Ne
ath
we
re
av
ail
ab
le.
Dis
ad
van
tag
e:
Pe
rmis
sio
n f
or
wo
rks
wit
hin
SS
SI
req
uir
ed
an
d u
nk
no
wn
co
nd
itio
n a
nd
su
ita
bil
ity
of
exi
stin
g d
uct
s u
nd
er
Ne
ath
.
Blu
e r
ou
te (
vari
ati
on
on
en
d o
f y
ell
ow
ro
ute
) –
Ad
va
nta
ge
: D
ire
ct
rou
te a
nd
re
du
ced
le
ng
th o
f ca
ble
s, w
ell
est
ab
lish
ed
tra
ck w
ith
in
the
SS
SI,
min
imu
m d
istu
rba
nce
to
th
e S
SS
I w
ith
ea
sy p
lan
t a
nd
eq
uip
me
nt
acc
ess
usi
ng
th
e e
xist
ing
tra
ck.
Dis
ad
van
tag
e:
Lon
ge
st
HD
D (
68
0m
).
Ora
ng
e a
nd
gre
en
ro
ute
s (v
ari
ati
on
on
en
d o
f y
ell
ow
ro
ute
) –
Ad
van
tag
e:
Th
e r
ou
te b
etw
ee
n p
oin
t 3
an
d 5
is
an
exi
stin
g r
ais
ed
tra
ck,
sho
rte
st H
DD
(3
50
m).
D
isa
dva
nta
ge
: E
xist
ing
tra
ck c
on
tain
s
con
cre
te a
nd
la
rge
bo
uld
ers
an
d w
ou
ld b
e d
iffi
cult
to
exc
av
ate
,
dif
ficu
lt a
cce
ss t
hro
ug
h S
SS
I, l
on
ge
st c
ab
le r
ou
te.
Ye
llo
w r
ou
te c
on
sid
ere
d w
ith
blu
e r
ou
te a
nd
se
ctio
ns
of
red
ro
ute
ke
pt
as
alt
ern
ati
ve
s.
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Se
pte
mb
er
- O
cto
be
r 2
01
3
We
ste
rn a
rm c
ab
le r
ou
te,
wit
h v
ari
ou
s o
pti
on
s
thro
ug
h t
he
un
ive
rsit
y c
am
pu
s (s
ee
pic
ture
, le
ft.
Th
e o
rig
ina
l F
ab
ian
Wa
y r
ou
te a
nd
ea
rlie
r e
ast
ern
arm
ro
ute
are
als
o s
ho
wn
).
Fo
llo
win
g f
urt
he
r d
eta
ile
d i
nfo
rma
tio
n r
eg
ard
ing
th
e
pla
n f
or
the
SU
BC
, se
ve
ral
op
tio
ns
we
re p
rop
ose
d,
incl
ud
ing
ru
nn
ing
pa
rall
el
(wh
ere
po
ssib
le)
to F
ab
ian
Wa
y,
an
d a
ro
ute
fo
llo
win
g t
he
ca
mp
us
pe
rim
ete
r.
Oct
ob
er
20
13
Ca
ble
ro
ute
wit
h o
pti
on
s a
s p
rev
iou
s, b
ut
wit
h t
he
rou
te r
elo
cate
d w
ith
in t
he
un
ive
rsit
y
tha
n r
un
nin
g i
n t
he
ve
rge
alo
ng
sid
e F
ab
ian
Wa
y.
We
ste
rn a
rm r
ou
te,
wit
h t
he
ca
ble
ro
ute
re
loca
ted
wit
hin
th
e u
niv
ers
ity
ca
mp
us
(se
e p
ictu
re,
left
).
Tid
al
Lag
oo
n S
wa
nse
a B
ay
plc
Oct
ob
er
20
13
We
ste
rn a
rm c
ab
le r
ou
te,
wit
h v
ari
ou
s o
pti
on
s
thro
ug
h t
he
un
ive
rsit
y c
am
pu
s (s
ee
pic
ture
, le
ft.
Th
e o
rig
ina
l F
ab
ian
Wa
y r
ou
te a
nd
ea
rlie
r e
ast
ern
als
o s
ho
wn
).
Fo
llo
win
g f
urt
he
r d
eta
ile
d i
nfo
rma
tio
n r
eg
ard
ing
th
e
pla
n f
or
the
SU
BC
, se
ve
ral
op
tio
ns
we
re p
rop
ose
d,
incl
ud
ing
ru
nn
ing
pa
rall
el
(wh
ere
po
ssib
le)
to F
ab
ian
Wa
y,
an
d a
ro
ute
fo
llo
win
g t
he
ca
mp
us
pe
rim
ete
r.
Th
e v
erg
e i
n F
ab
ian
Wa
y i
s li
ke
ly t
o b
e s
ign
ific
an
tly
na
rro
we
d t
o
all
ow
be
tte
r ro
ad
acc
ess
to
th
e c
am
pu
s, t
hu
s li
mit
ing
th
e s
pa
ce f
or
the
ca
ble
ro
ute
an
d r
en
de
rin
g t
his
op
tio
n u
nsu
ita
ble
.
Th
e p
rop
ose
d r
ou
te p
ara
lle
l to
Fa
bia
n W
ay
is
lik
ely
to
en
cou
nte
r
pin
ch p
oin
ts a
nd
ma
y c
lash
wit
h p
lan
ne
d
Th
e r
ou
te f
oll
ow
ing
th
e c
am
pu
s p
eri
me
ter
is l
ike
ly t
o i
ncr
ea
se t
he
nu
mb
er
of
cro
sse
d s
erv
ice
s a
nd
wil
l a
lso
in
cre
ase
th
e o
ve
rall
len
gth
of
the
ro
ute
. P
ha
se 2
of
the
un
ive
rsit
y c
am
pu
s e
xpa
nsi
on
is
exp
ect
ed
on
th
is s
ite
, a
nd
th
ere
fore
a
pe
rim
ete
r m
ay
ca
use
iss
ue
s fo
r fu
ture
co
nst
ruct
ion
.
Pin
k o
pti
on
th
rou
gh
th
e U
niv
ers
ity
sit
e i
s co
nsi
de
red
(se
e b
elo
w).
Ca
ble
ro
ute
wit
h o
pti
on
s a
s p
rev
iou
s, b
ut
wit
h t
he
rou
te r
elo
cate
d w
ith
in t
he
un
ive
rsit
y c
am
pu
s ra
the
r
tha
n r
un
nin
g i
n t
he
ve
rge
alo
ng
sid
e F
ab
ian
Wa
y.
We
ste
rn a
rm r
ou
te,
wit
h t
he
ca
ble
ro
ute
re
loca
ted
wit
hin
th
e u
niv
ers
ity
ca
mp
us
(se
e p
ictu
re,
left
).
Fo
llo
win
g i
nfo
rma
tio
n r
eg
ard
ing
th
e S
UB
C,
an
op
tio
n t
o r
elo
cate
the
ro
ute
wit
hin
ca
mp
us
pa
rall
el
wit
h F
ab
ian
Wa
y w
as
exa
min
ed
.
Th
is w
as
in r
esp
on
se t
o a
su
gg
est
ion
th
at
du
cts
cou
ld b
e i
nst
all
ed
as
the
ca
mp
us
is c
on
stru
cte
d i
n o
rde
r fo
r th
e c
ab
le t
o b
e p
ull
ed
thro
ug
h i
n t
he
fu
ture
.
Dis
ad
van
tag
e o
f th
is o
pti
on
wo
uld
be
th
at
it m
ay
be
dif
ficu
lt t
o
en
ter
the
Fa
bia
n W
ay
ve
rge
at
this
po
int
du
e t
o v
eg
eta
tio
n a
nd
a
ne
arb
y b
rid
ge
.
Op
tio
n c
on
sid
ere
d –
fu
rth
er
info
rma
tio
n r
eq
uir
ed
.
Pa
ge
3-
25
be
sig
nif
ica
ntl
y n
arr
ow
ed
to
all
ow
be
tte
r ro
ad
acc
ess
to
th
e c
am
pu
s, t
hu
s li
mit
ing
th
e s
pa
ce f
or
the
ca
ble
ro
ute
an
d r
en
de
rin
g t
his
op
tio
n u
nsu
ita
ble
.
Th
e p
rop
ose
d r
ou
te p
ara
lle
l to
Fa
bia
n W
ay
is
lik
ely
to
en
cou
nte
r
pin
ch p
oin
ts a
nd
ma
y c
lash
wit
h p
lan
ne
d l
an
dsc
ap
ing
wo
rks.
Th
e r
ou
te f
oll
ow
ing
th
e c
am
pu
s p
eri
me
ter
is l
ike
ly t
o i
ncr
ea
se t
he
nu
mb
er
of
cro
sse
d s
erv
ice
s a
nd
wil
l a
lso
in
cre
ase
th
e o
ve
rall
len
gth
of
the
ro
ute
. P
ha
se 2
of
the
un
ive
rsit
y c
am
pu
s e
xpa
nsi
on
is
exp
ect
ed
on
th
is s
ite
, a
nd
th
ere
fore
a r
ou
te f
oll
ow
ing
th
e c
am
pu
s
pe
rim
ete
r m
ay
ca
use
iss
ue
s fo
r fu
ture
co
nst
ruct
ion
.
Pin
k o
pti
on
th
rou
gh
th
e U
niv
ers
ity
sit
e i
s co
nsi
de
red
(se
e b
elo
w).
Fo
llo
win
g i
nfo
rma
tio
n r
eg
ard
ing
th
e S
UB
C,
an
op
tio
n t
o r
elo
cate
el
wit
h F
ab
ian
Wa
y w
as
exa
min
ed
.
Th
is w
as
in r
esp
on
se t
o a
su
gg
est
ion
th
at
du
cts
cou
ld b
e i
nst
all
ed
as
the
ca
mp
us
is c
on
stru
cte
d i
n o
rde
r fo
r th
e c
ab
le t
o b
e p
ull
ed
Dis
ad
van
tag
e o
f th
is o
pti
on
wo
uld
be
th
at
it m
ay
be
dif
ficu
lt t
o
ter
the
Fa
bia
n W
ay
ve
rge
at
this
po
int
du
e t
o v
eg
eta
tio
n a
nd
a
furt
he
r in
form
ati
on
re
qu
ire
d.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
26
Oct
ob
er
20
13
Ca
ble
ro
ute
fro
m t
he
tu
rbin
e h
ou
se t
o t
he
Ba
gla
n
Ba
y s
ub
sta
tio
n,
foll
ow
ing
th
e e
ast
ern
bre
ak
wa
ter,
an
d f
rom
th
e b
rea
kw
ate
r la
nd
ing
po
int
thro
ug
h
the
SU
BC
. T
he
pro
po
sed
pa
th v
ia F
ab
ian
Wa
y i
s
the
n f
oll
ow
ed
, e
nte
rin
g t
he
SS
SI
zon
e p
rio
r to
th
e
rou
nd
ab
ou
t.
Th
e r
ou
te t
he
n u
ses
eit
he
r th
e
exi
stin
g d
uct
s o
r n
ew
dir
ect
ion
al
dri
llin
g t
o c
ross
the
riv
er
be
fore
fo
llo
win
g t
he
exi
stin
g p
ath
on
lan
d t
o t
he
Ba
gla
n B
ay
Su
bst
ati
on
.
Ea
ste
rn a
rm,
via
th
e u
niv
ers
ity
ca
mp
us.
Ap
pro
xim
ate
ro
ute
le
ng
th:
10
.6k
m
Alt
ho
ug
h c
ross
ing
fe
we
r e
xist
ing
se
rvic
es
an
d l
ess
exi
stin
g l
an
d,
the
ad
dit
ion
al
len
gth
of
the
ca
ble
ro
ute
is
lik
ely
to
co
st a
pp
roxi
ma
tely
£1
.2m
illi
on
ext
ra,
the
refo
re m
ak
ing
it
no
t fi
na
nci
all
y v
iab
le.
Fu
rth
erm
ore
, th
e e
ast
ern
arm
ha
s n
ot
be
en
de
sig
ne
d f
or
ve
hic
ula
r
acc
ess
, a
nd
so
acc
ess
to
th
e c
ab
le m
ay
be
pro
ble
ma
tic.
A r
ou
te d
ive
rgin
g a
t th
e p
oin
t a
t w
hic
h t
he
ea
ste
rn a
rm t
urn
s n
ort
h
tow
ard
s th
e S
UB
C w
as
als
o c
on
sid
ere
d.
Th
is r
ou
te w
ou
ld r
un
un
de
rwa
ter
to t
he
Riv
er
Ne
ath
cro
ssin
g b
efo
re f
oll
ow
ing
th
e
exi
stin
g r
oa
d t
o t
he
Ba
gla
n B
ay
su
bst
ati
on
. A
lth
ou
gh
be
ing
a
sho
rte
r o
ve
rall
ro
ute
, th
e c
ost
s o
f th
e u
nd
erw
ate
r ca
ble
to
ge
the
r
wit
h m
ain
ten
an
ce c
ost
s a
re l
ike
ly t
o m
ak
e t
his
ro
ute
no
t
eco
no
mic
all
y v
iab
le.
Op
tio
ns
reje
cte
d.
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay - Environmental Statement
Site Selection and Option Appraisal Page 3- 27
3.8 Water quality optimisation applications
3.8.0.1 Water quality within the Bay and within the Lagoon comprised in the Project will be
affected by the presence of the Swansea long sea outfall. This currently discharges within
the lagoon area. Under normal dry weather conditions the outfall from the Swansea
waste water treatment works (WWTW) discharges high quality, fully treated and UV
disinfected effluent. During significant rainfall events the outfall will also discharge dilute
storm water which carries a more notable bacterial load. Without mitigation, during
these rainfall events there is a potential for the water from within the lagoon area to:
A. affect the water quality at the designated bathing waters of Swansea Bay and
Aberafan; and
B. reduce the water quality within the lagoon thereby affecting the potential for all
year round water contact sport usage.
3.8.0.2 As discussed in Table 3.1 in the early stages of the Project the location of the turbine
housing was assessed and optimised to minimise impacts on designated bathing waters
at Aberafan. This was achieved through the selection of a south to westerly facing
turbine housing. The detailed assessment in Chapter 7, Marine Water Quality confirms
that the untreated discharge of storm water would not affect the compliance of these
designated bathing waters.
3.8.0.3 With respect to water quality within the lagoon, during rainfall events when a storm
water spill may occur, the water quality would be reduced in the absence of further
mitigation and this would preclude the use for water contact sports at or after such
events. As such, for all year round water contact sport usage, options to address the
storm discharges from the WWTW are important.
3.8.0.4 Three options were originally considered to reduce the effects of storm discharges from
the Swansea WWTW. The options are summarised in Table 3.3, and a high level
indication of the engineering feasibility and estimated cost (which serves as a proxy for
use of resources and difficulty of delivery), carbon footprint and construction timescale
for each option is also provided.
3.8.0.5 Options 1 (Storm Water Storage) and 2 (Storm Water Disinfection) address the discharge
of storm water from the WWTW, by reducing either frequency of operation or discharge
concentration. This would improve water quality both within the lagoon and within
Swansea Bay. Option 3 (Outfall Extension) would completely remove the treated
effluent and storm discharges from the lagoon, into the Bay.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay -
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
28
Ta
ble
3.3
Co
mp
ari
son
of
op
tim
isa
tio
n
op
tio
ns
Fe
asi
bil
ity
C
ost
1
Tim
esc
ale
2
Ca
rbo
n
Fo
otp
rin
t
Op
tio
n 1
Sto
rm W
ate
r S
tora
ge
a)
Sto
rag
e o
f st
orm
dis
cha
rge
flo
ws
fro
m t
he
WW
TW
s
ne
ar
to t
he
Pro
ject
/WW
TW
.
Eff
lue
nt
is s
tore
d
un
til
it c
an
be
retu
rne
d t
o t
he
WW
TW
fo
r
tre
atm
en
t.
OR
Ad
va
nta
ge
s
Re
du
ces
sto
rm d
isch
arg
es
to a
ve
ry s
ma
ll n
um
be
r, i
.e.
on
ly u
nd
er
ext
rem
e r
ain
fall
co
nd
itio
ns.
Sto
rm f
low
s re
turn
ed
to
WW
TW
fo
r fu
ll t
rea
tme
nt,
re
du
cin
g n
et
imp
act
of
sto
rm f
low
s.
Dis
ad
va
nta
ge
s
Sto
rag
e r
eq
uir
em
en
t is
ext
rem
ely
la
rge
, p
ote
nti
all
y i
n e
xce
ss o
f 1
50
,00
0 m
3.
Th
e l
an
d r
eq
uir
ed
is
un
lik
ely
to
be
ava
ila
ble
wit
hin
Pro
ject
Are
a f
or
a s
ing
le s
tora
ge
so
luti
on
.
Larg
e (
pro
hib
itiv
e)
con
stru
ctio
n c
ost
s.
Re
turn
ing
sto
red
eff
lue
nt
to t
he
WW
TW
wo
uld
be
dif
ficu
lt a
s th
e c
ap
aci
ty o
f th
e W
WT
W i
s
lim
ite
d t
o i
ts d
esi
gn
flo
ws.
Sig
nif
ica
nt
pu
mp
ing
to
/ f
rom
sto
rag
e r
eq
uir
ed
.
If s
torm
sto
rag
e c
an
no
t b
e e
mp
tie
d b
etw
ee
n s
torm
s a
dd
itio
na
l sp
ills
wo
uld
occ
ur.
Tim
e t
ak
en
to
re
turn
sto
red
eff
lue
nt
to t
he
WW
TW
wo
uld
pre
sen
t ri
sk o
f o
do
urs
.
Vo
lum
e o
f st
ora
ge
ma
y n
ot
ke
ep
pa
ce w
ith
ch
an
ge
s in
th
e c
atc
hm
en
t o
r ra
infa
ll p
att
ern
s.
Larg
e e
mb
ed
de
d c
arb
on
fo
otp
rin
t.
On
go
ing
pu
mp
ing
an
d m
ain
ten
an
ce c
ost
s a
nd
po
we
r n
ee
ds.
LOW
H
IGH
ES
T
>£
20
0M
SH
OR
T
HIG
HE
ST
b)
Pro
visi
on
of
sto
rag
e
an
d s
torm
wa
ter
rem
ova
l in
th
e
catc
hm
en
t
up
stre
am
of
the
WW
TW
(w
hic
h
wo
uld
ne
ed
to
be
imp
lem
en
ted
in
ag
ree
me
nt
an
d
coo
pe
rati
on
wit
h
DC
WW
).
Ad
va
nta
ge
s
Re
du
ces
sto
rm f
low
s to
WW
TW
by
re
mo
vin
g s
torm
wa
ter
at
sou
rce
in
th
e c
atc
hm
en
t.
Re
du
ces
sto
rm d
isch
arg
es
to a
ve
ry s
ma
ll n
um
be
r, i
.e.
on
ly u
nd
er
ext
rem
e r
ain
fall
co
nd
itio
ns.
Mo
re e
ffic
ien
t a
lte
rna
tiv
e t
o s
tora
ge
at
the
WW
TW
re
qu
irin
g l
ess
sto
rag
e v
olu
me
, p
um
pin
g
etc
.
Imp
rove
me
nts
th
rou
gh
ou
t th
e c
atc
hm
en
t, a
dd
itio
na
l b
en
efi
ts t
o S
wa
nse
a B
ay
wa
ter
qu
ali
ty.
Dis
ad
va
nta
ge
s
So
luti
on
s ca
nn
ot
be
id
en
tifi
ed
at
this
sta
ge
, fu
ll n
etw
ork
ass
ess
me
nt
req
uir
ed
.
So
luti
on
s m
ay
re
qu
ire
ma
ny
ye
ars
to
de
sig
n a
nd
im
ple
me
nt.
So
luti
on
ma
y n
ot
pro
vid
e s
uff
icie
nt
spil
l re
du
ctio
n a
t th
e W
WT
W.
Imp
lem
en
tati
on
an
d t
ime
sca
le w
ou
ld b
e b
ey
on
d t
he
co
ntr
ol
of
TLS
B.
Ad
dit
ion
al
sto
rag
e m
ay
sti
ll b
e r
eq
uir
ed
at
the
WW
TW
, a
lth
ou
gh
le
ss t
ha
n u
nd
er
me
tho
d a
).
Dis
ad
van
tag
es
ide
nti
fie
d u
nd
er
a)
wo
uld
be
lik
ely
to
re
ma
in,
alt
ho
ug
h r
ed
uce
d i
n m
ag
nit
ud
e.
HIG
H
HIG
H
<£
20
0M
LON
G
MID
1
Co
st e
stim
ate
s a
re p
relim
ina
ry b
ase
d o
n p
rev
iou
s sc
he
me
s. Im
pro
ve
d c
ost
est
ima
tes
for
op
tio
ns
are
be
ing
de
term
ine
d i
n c
on
sult
ati
on
wit
h D
CW
W
2
Tim
esc
ale
: S
ho
rt–
co
mp
leti
on
wit
hin
la
go
on
co
nst
ruct
ion
pe
rio
d.
Lo
ng
– g
rea
ter
tha
n la
go
on
co
nst
ruct
ion
pe
rio
d.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay -
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
29
Ta
ble
3.3
Co
nt.
Fe
asi
bil
ity
C
ost
1
Tim
esc
ale
2
Ca
rbo
n
Fo
otp
rin
t
Op
tio
n 2
Sto
rm W
ate
r
Dis
infe
ctio
n
UV
tre
atm
en
t o
f ra
w
sto
rm w
ate
r to
re
du
ce
FIO
s a
nd
pa
tho
ge
ns.
Ad
va
nta
ge
s
Sim
ila
r te
chn
olo
gy
UV
dis
infe
ctio
n o
f th
e S
wa
nse
a W
WT
W f
ina
l e
fflu
en
t.
Pro
ven
te
chn
olo
gy
wh
ich
ha
s b
ee
n s
ucc
ess
full
y a
pp
lie
d a
t a
nu
mb
er
of
loca
tio
ns
in
So
uth
Wa
les.
Sm
all
fo
otp
rin
t, c
ou
ld b
e a
cco
mm
od
ate
d w
ith
in a
vail
ab
le l
an
d a
t W
WT
W.
Re
du
ctio
n i
n i
nd
ica
tor
org
an
ism
s o
f b
etw
ee
n 1
00
an
d 6
00
tim
es
can
be
ach
ieve
d.
Ava
ila
ble
all
of
the
tim
e t
o t
rea
t a
ll s
torm
s.
All
flo
ws
can
be
tre
ate
d b
y a
su
ffic
ien
tly
la
rge
pla
nt.
Ca
n a
cco
mm
od
ate
fu
ture
ch
an
ge
in
th
e c
atc
hm
en
t e
.g.
- g
row
th o
r ch
an
ge
s in
ra
infa
ll p
att
ern
s (o
pe
rate
mo
re).
- re
du
ctio
ns
in s
torm
wa
ter
flo
ws
fro
m f
utu
re D
CW
W i
mp
rove
me
nts
(o
pe
rate
le
ss).
En
erg
y c
on
sum
pti
on
re
lati
ve
ly l
ow
, o
nly
re
qu
ire
d w
he
n s
torm
s fl
ow
s o
ccu
r.
Ca
n b
e u
pd
ate
d a
nd
im
pro
ved
wit
h a
dva
nce
me
nts
in
te
chn
olo
gy
ove
r th
e l
ife
tim
e o
f
the
Pro
ject
.
Dis
ad
va
nta
ge
s
Hig
h U
V d
ose
ne
ed
ed
, re
qu
irin
g s
pe
cia
lly
de
sig
ne
d U
V p
lan
t (s
ep
ara
te t
o e
xist
ing
on
e).
De
sig
n m
ust
be
ab
le t
o e
nsu
re s
uff
icie
nt
ba
cte
ria
re
mo
val
for
wid
e r
an
ge
of
flo
w /
turb
idit
y c
on
dit
ion
s.
Po
we
r re
qu
ire
d t
o p
ow
er
UV
la
mp
s.
Sy
ste
m/l
am
ps
mu
st b
e m
ain
tain
ed
to
en
sure
op
era
tio
n/d
ose
ava
ila
ble
wh
en
ne
ed
ed
.
Sp
eci
al
con
sen
tin
g r
eq
uir
em
en
ts.
UV
sy
ste
m f
ail
ure
wo
uld
all
ow
un
tre
ate
d d
isch
arg
e –
ba
ck-u
p p
roce
du
res
req
uir
ed
(e.g
. p
reve
nti
on
of
acc
ess
to
la
go
on
fo
r co
nta
ct w
ate
r sp
ort
s if
sto
rm e
ven
t a
nd
UV
tre
atm
en
t n
ot
fun
ctio
nin
g).
HIG
H
LEA
ST
£8
-12
M
SH
OR
T
MID
1
Co
st e
stim
ate
s a
re p
relim
ina
ry b
ase
d o
n p
rev
iou
s sc
he
me
s. Im
pro
ve
d c
ost
est
ima
tes
for
op
tio
ns
are
be
ing
de
term
ine
d i
n c
on
sult
ati
on
wit
h D
CW
W
2
Tim
esc
ale
: S
ho
rt–
co
mp
leti
on
wit
hin
la
go
on
co
nst
ruct
ion
pe
rio
d.
Lo
ng
– g
rea
ter
tha
n la
go
on
co
nst
ruct
ion
pe
rio
d.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay -
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
30
Ta
ble
3.3
Co
nt.
Fe
asi
bil
ity
C
ost
1
Tim
esc
ale
2
Ca
rbo
n
Fo
otp
rin
t
Op
tio
n
3
–
Ou
tfa
ll
Ex
ten
sio
n
Ext
en
sio
n o
f th
e e
xist
ing
ou
tfa
ll t
o p
lace
th
e
dis
cha
rge
po
int
ou
tsid
e
of
the
la
go
on
.
Ad
va
nta
ge
s
Pla
ces
ou
tfa
ll
be
yo
nd
la
go
on
im
po
un
dm
en
t a
nd
in
d
ee
pe
r w
ate
r w
ith
p
ote
nti
all
y
hig
he
r d
isp
ers
ion
.
Low
en
erg
y c
on
sum
pti
on
.
Low
ma
inte
na
nce
on
ce i
nst
all
ed
.
Un
lik
ely
to
be
aff
ect
ed
by
fu
ture
gro
wth
or
cha
ng
es
in r
ain
fall
pa
tte
rns.
Dis
ad
va
nta
ge
s
Dis
cha
rge
im
pa
cts
ma
y b
e m
ove
d t
o o
ffsh
ore
wa
ters
or
incr
ea
sed
alo
ng
ad
jace
nt
coa
stli
ne
.
Ou
tfa
ll m
ust
pa
ss u
nd
er
the
la
go
on
wa
ll w
ith
ou
t ri
sk t
o t
he
ou
tfa
ll p
ipe
, a
nd
wit
ho
ut
com
pro
mis
ing
th
e i
nte
gri
ty o
f th
e l
ag
oo
n w
all
.
Co
nn
ect
ing
th
e e
xte
nsi
on
to
th
e e
xist
ing
ou
tfa
ll w
ou
ld r
eq
uir
e t
em
po
rary
div
ers
ion
of
dis
cha
rge
fro
m t
he
WW
TW
du
rin
g t
he
co
nn
ect
ion
pe
rio
d.
Gro
un
d c
on
dit
ion
s a
nd
wa
ter
de
pth
ma
y m
ak
e o
utf
all
ext
en
sio
n d
iffi
cult
.
Th
e a
dd
itio
na
l le
ng
th o
f o
utf
all
ma
y h
ave
hy
dra
uli
c e
ffe
cts
at
the
WW
TW
s, a
nd
co
uld
po
ten
tia
lly
re
qu
ire
pu
mp
ing
of
the
dis
cha
rge
to
ove
rco
me
, w
ith
in
cre
ase
d o
pe
rati
on
al
risk
s a
nd
co
sts.
MID
H
IGH
£2
5-3
0M
SH
OR
T
LEA
ST
1
Co
st e
stim
ate
s a
re p
relim
ina
ry b
ase
d o
n p
rev
iou
s sc
he
me
s. Im
pro
ve
d c
ost
est
ima
tes
for
op
tio
ns
are
be
ing
de
term
ine
d i
n c
on
sult
ati
on
wit
h D
CW
W
2
Tim
esc
ale
: S
ho
rt–
co
mp
leti
on
wit
hin
la
go
on
co
nst
ruct
ion
pe
rio
d.
Lo
ng
– g
rea
ter
tha
n la
go
on
co
nst
ruct
ion
pe
rio
d.
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 31
3.8.0.6 Owing to a number of issues, including the high cost, practicalities of implementation
and limited benefits, which do not apply to the two remaining solutions, storm storage
has not been taken forward as part of the Project. UV disinfection of storm water and
outfall extension have been considered further in this EIA and details of the modelling
runs and results can be found in Chapter 7, Marine Water Quality.
3.9 Decommissioning options
3.9.0.1 In Chapter 4 Project description, the options for the treatment of the Project at the end
of its predicted 120-year lifespan that are assessed are discussed. However, the more
radical approach of the complete or partial removal of the Project from Swansea Bay has
also been considered and is described below, as well as an explanation of the choice not
to progress this option with a description of the environmental reasons behind that
selection.
3.9.0.2 The Project has been designed to be operational for up to 120 years and a Development
Consent Order is being applied for on this basis (see Chapter 1). Appropriate works will
be undertaken over this timescale in order that the condition of the structures will be
maintained such that electricity generation will be continued. At the end of this period,
it is considered that with refurbishment and regular maintenance, the Project could be
functional for electricity generation for a further 50 years. Once the capital costs
associated with construction of the Project have been paid off, the Project will be a cost-
effective source of electricity, and as such, retaining the Project would be of benefit to
meeting future renewable energy targets. For a similar project, La Rance, a tidal barrage
in Brittany, France which generates 240MW of electricity, the capital cost for
construction in 1960-66 was 620 million Francs, which is approximately 94.5 million
Euros at 2011 prices. Capital costs have been recovered and electricity production costs
in 2011 were 18 Euro cents per kWh, compared with nuclear generation at 25 Euro cent
per kWh2.
3.9.0.3 If at some future time, alternative energy sources have been developed that are more
cost effective, proposals for decommissioning the Project are likely to be considered. At
that time, it is likely that the Project would have been in-situ for a period of at least 120
years, and would have become an established recreational, leisure, art and educational
facility (see Chapter 4 and 22 for further information). In addition, a stable marine
environment would have been created as a result of the artificial reef habitat formed by
the rocky seawall and the impoundment of the waterbody.
3.9.0.4 Wholesale decommissioning, involving removal of the entire structure would result in
loss of the facilities described above, as well as significant environmental effects to then
established marine and terrestrial ecological habitats, which could otherwise be avoided.
The works would be likely to involve or require:
i. Demolition of the concrete turbine and sluice gate housing structure – probably
using explosives to demolish the concrete works in sections. The concrete would be
removed by vehicle, crushed and re-used. Reinforcing steel would be salvaged and
recycled. The sheet-piles would be cut-off and left in situ embedded below the
seabed.
2http://www.theecologist.org/News/news_analysis/678082/how_france_eclipsed_the_uk_with_brittany_tidal_success_stor
y.html
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 32
ii. Scour protection – the concrete scour protection mattress would be left in-situ as it
would not result in obstruction of movement of sediment, water or navigation.
iii. Demolition of onshore and offshore buildings. The Offshore Building would be
demolished, but the options for retention of the Western Landfall building would be
considered.
iv. Demolition of seawalls – two options could be considered for removal of the
seawalls: Option A – removal of entire structure; and Option B – retention of
sections of eastern and western seawalls. These options are described further in
Table 3.4.
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
33
Ta
ble
3.4
D
eco
mm
issi
on
ing
of
sea
wa
ll o
pti
on
s
Op
tio
n D
esc
rip
tio
n
Exp
ect
ed
de
mo
liti
on
act
ivit
ies
Op
tio
n
A:
Re
mo
va
l o
f e
nti
re w
est
ern
a
nd
e
ast
ern
se
aw
all
s
an
d a
sso
cia
ted
fa
cili
tie
s.
Th
e s
ea
wa
lls
wo
uld
be
re
mo
ved
wo
rkin
g f
rom
off
sho
re t
o o
nsh
ore
.
Th
e c
on
cre
te c
ap
wo
uld
be
bro
ke
n
up
(b
last
ing
o
r u
se
of
ha
mm
er/
chis
el)
.
It
is
est
ima
ted
th
at
ap
pro
xim
ate
ly
20
0,0
00
m3
(50
0,0
00
to
nn
es)
of
con
cre
te w
ou
ld b
e d
em
oli
she
d.
So
me
of
this
ma
teri
al
wo
uld
be
cru
she
d a
nd
re
-
use
d b
ut
du
e t
o t
he
la
rge
am
ou
nt
ge
ne
rate
d,
it i
s e
xpe
cte
d t
ha
t a
sig
nif
ica
nt
pro
po
rtio
n w
ou
ld n
ee
d
to b
e t
ran
spo
rte
d b
y r
oa
d t
o l
an
dfi
ll.
Th
e r
ock
arm
ou
r w
ou
ld b
e r
em
ov
ed
by
cra
ne
an
d t
ruck
. A
pp
roxi
ma
tely
2.5
mil
lio
n t
on
ne
s o
f ro
ck
arm
ou
r w
ill
be
re
mo
ve
d b
ase
d.
To
sto
ck p
ile
th
is a
mo
un
t o
f ro
ck w
ou
ld r
eq
uir
e a
te
mp
ora
ry
sto
rag
e a
rea
of
ap
pro
xim
ate
ly 1
00
he
cta
res
of
lan
d.
Alt
ern
ati
ve u
ses
of
this
ro
ck w
ou
ld n
ee
d t
o b
e
inve
stig
ate
d a
t th
e t
ime
of
de
com
mis
sio
nin
g a
s lo
cal
lan
d a
vail
ab
ilit
y f
or
rock
sto
ckp
ilin
g i
s u
nli
ke
ly
to b
e a
vail
ab
le w
ith
th
e p
ote
nti
al
syn
erg
y o
f d
ev
elo
pm
en
t w
ith
in t
he
Po
rt a
nd
su
rro
un
din
g a
rea
ove
r th
e i
nte
rve
nin
g y
ea
rs.
Re
mo
val
of
Ge
otu
be
s® –
an
tici
pa
ted
me
tho
do
log
y:
th
e G
eo
tub
es®
wo
uld
be
exp
ose
d a
nd
th
en
cu
t
op
en
alo
ng
th
eir
le
ng
th p
oss
ibly
by
div
ers
. C
on
tain
ed
se
dim
en
t w
ou
ld b
e e
rod
ed
ove
r su
bse
qu
en
t
tid
al
cycl
es
or
if d
ee
me
d n
ece
ssa
ry,
ba
sed
on
pre
dic
tive
co
ast
al
mo
de
llin
g t
he
se
dim
en
t u
nd
ert
ak
en
at
the
tim
e o
f d
eco
mm
issi
on
ing
, co
uld
be
dre
dg
ed
an
d d
isp
ose
d o
f to
a l
ice
nse
d d
red
gin
g d
isp
osa
l
site
. T
he
ge
ofa
bri
c w
ou
ld t
he
n b
e r
em
ov
ed
wh
ere
exp
ose
d u
sin
g g
rab
s.
Po
ten
tia
l d
iffi
cult
ies
cou
ld
ari
se w
ith
re
trie
val
of
the
ma
teri
al
if a
ny
se
dim
en
t is
re
tain
ed
wh
ich
ma
y r
esu
lt i
n t
ea
rin
g.
An
y
ma
teri
al
left
be
hin
d i
s li
ke
ly t
o b
e w
ash
ed
ash
ore
an
d t
his
wo
uld
ne
ed
to
be
co
lle
cte
d a
nd
dis
po
sed
of
ove
r ti
me
.
Se
dim
en
t w
ith
in s
ea
wa
lls
– t
his
wo
uld
eit
he
r b
e a
llo
we
d t
o s
cou
r a
wa
y n
atu
rall
y o
ver
tid
al
cycl
es
or
dre
dg
ed
an
d d
isp
ose
d o
f a
s fo
r th
e G
eo
tub
es®
se
dim
en
t.
Ho
we
ve
r, d
ue
to
th
e l
arg
e v
olu
me
s o
f
ma
teri
al,
th
e l
ate
r is
mo
re l
ike
ly t
o b
e r
eq
uir
ed
in
ce
rta
in a
rea
s a
ffe
cte
d b
y i
ncr
ea
sed
se
dim
en
t
de
po
siti
on
. D
isp
osa
l o
f th
is d
red
ge
d m
ate
ria
l w
ou
ld b
e t
o a
lic
en
sed
dre
dg
ing
dis
po
sal
site
.
Dis
po
sal
of
wa
ste
ma
teri
al
ge
ne
rate
d a
s a
re
sult
of
the
de
mo
liti
on
of
the
Pro
ject
is
lik
ely
to
be
sig
nif
ica
nt
an
d a
pp
rop
ria
te d
isp
osa
l ro
ute
s w
ou
ld h
ave
to
be
id
en
tifi
ed
ne
are
r th
e t
ime
.
Re
mo
val
of
the
en
tire
str
uct
ure
wo
uld
sig
nif
ica
ntl
y a
ffe
ct e
sta
bli
she
d i
nte
rtid
al
an
d s
ub
tid
al
ma
rin
e
en
viro
nm
en
ts a
nd
its
re
cre
ati
on
al
an
d l
eis
ure
use
. T
em
po
rary
im
pa
cts
wo
uld
als
o b
e e
xpe
rie
nce
fro
m d
eco
mm
issi
on
ing
no
ise
, d
isru
pti
on
to
na
vig
ati
on
, w
ate
r q
ua
lity
an
d c
oa
sta
l p
roce
sse
s.
In
term
s o
f te
rre
stri
al
ha
bit
ats
, th
e e
xte
nsi
on
of
san
d d
un
es
is l
ike
ly t
o h
ave
occ
urr
ed
alo
ng
th
e
T
ida
l La
go
on
Sw
an
sea
Ba
y p
lc
Tid
al L
ag
oo
n S
wa
nse
a B
ay –
En
vir
on
me
nta
l Sta
tem
en
t
Sit
e S
ele
ctio
n a
nd
Op
tio
n A
pp
rais
al
Pa
ge
3-
34
ea
ste
rn w
all
. T
he
re
mo
val
of
the
ea
ste
rn w
all
wo
uld
me
an
th
at
an
y sa
nd
in
th
is a
rea
wo
uld
be
mo
ve
we
stw
ard
acr
oss
th
e L
ag
oo
n b
ea
ch.
It
is l
ike
ly t
ha
t m
itig
ati
on
th
rou
gh
re
mo
val
an
d d
isp
osa
l o
f th
is
san
d w
ou
ld b
e n
ece
ssa
ry.
Pa
rt o
f th
e w
est
ern
la
go
on
se
aw
all
wo
uld
ne
ed
to
be
re
tain
ed
to
co
nti
nu
e t
he
fu
nct
ion
of
the
curr
en
t e
ast
ern
Po
rt b
rea
kw
ate
r.
Op
tio
n
B:
Re
ten
tio
n
of
10
00
m
of
we
ste
rn
sea
wa
ll
an
d
rete
nti
on
of
50
0m
of
ea
ste
rn s
ea
wa
ll
Re
mo
val
me
tho
ds
as
de
scri
be
d a
bo
ve
. D
em
oli
tio
n w
ork
s w
ou
ld r
esu
lt i
n l
ess
im
pa
ct t
o i
nte
r-ti
da
l
are
as
alt
ho
ug
h a
sim
ila
r im
pa
ct t
o t
he
su
bti
da
l a
rea
s w
ou
ld b
e e
xpe
rie
nce
d.
Th
ere
wo
uld
be
le
ss
ma
teri
al
for
dis
po
sal
ge
ne
rate
d a
ga
in r
ed
uci
ng
ove
rall
im
pa
cts
in t
erm
s o
f n
ois
e,
wa
ter
qu
ali
ty,
coa
sta
l p
roce
sse
s a
nd
na
vig
ati
on
.
Th
ere
wo
uld
sti
ll b
e p
ote
nti
al
eff
ect
s o
n l
eis
ure
an
d r
ecr
ea
tio
na
l fa
cili
tie
s a
lth
ou
gh
at
a s
lig
htl
y
red
uce
d l
ev
el.
Th
e w
est
ern
se
aw
all
wil
l p
rovi
de
pro
tect
ion
to
th
e e
ntr
an
ce o
f S
wa
nse
a P
ort
. I
n
ad
dit
ion
, th
e W
est
ern
La
nd
fall
Bu
ild
ing
is
ho
use
d o
n t
his
se
ctio
n o
f th
e s
ea
wa
ll.
Th
e s
he
lte
red
be
ach
an
d w
ate
r e
nvi
ron
me
nt
to t
he
ea
st o
f th
e s
ea
wa
ll w
ill
be
ava
ila
ble
fo
r co
nti
nu
ed
use
fo
r re
cre
ati
on
an
d l
eis
ure
.
Po
ten
tia
l e
ffe
cts
on
te
rre
stri
al
eco
log
ica
l h
ab
ita
ts w
ou
ld a
lso
be
le
ss a
s th
e r
ete
nti
on
of
pa
rt o
f th
e
ea
ste
rn
lag
oo
n
sea
wa
ll
wo
uld
m
ain
tain
a
ny
sa
nd
d
un
e
syst
em
w
hic
h
ha
s e
sta
bli
she
d
he
re.
No
twit
hst
an
din
g t
his
re
mo
val
of
the
re
ma
inin
g s
ea
wa
ll m
ay
re
sult
in
ero
sio
n o
f th
e b
ea
ch a
nd
po
ten
tia
lly
du
ne
sy
ste
m i
n t
his
are
a a
nd
as
such
ap
pro
pri
ate
co
mp
ute
r m
od
ell
ing
to
ols
ava
ila
ble
at
the
tim
e w
ou
ld b
e u
sed
to
ass
ess
th
e p
ote
nti
al
eff
ect
s. I
f re
tain
ed
, th
is s
ect
ion
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Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 35
3.9.0.5 As can be seen from Table 3.4, proposals to decommission the Project involving removal
of the entire structure or parts of the structure are likely to result in significant effects,
particularly in terms of recreational and leisure use of the facility, disposal of waste
material and effects on established intertidal and subtidal marine habitats.
3.9.0.6 It is therefore considered that decommissioning options should be focused around
retaining the socio-economic potential of the facility whilst minimising potential
environmental effects. To this end, it is proposed that at the end of its operational life,
the turbine and sluice gates and associated mechanical and electrical equipment within
the concrete turbine housing structure will be removed. This will allow unhindered flow
of water to occur into and out of the lagoon over the tidal cycle equalising water levels.
Removal of the concrete turbine housing could be undertaken, but this would result in a
loss of connectivity between the eastern and western seawalls reducing the benefit for
recreational use. The cable connection between the Project and Baglan power station
could be dug up and the cables removed and recycled. At the time of decommissioning,
agreements would be sought as to the responsibility for maintenance of the structure for
public use.
3.10 Project infrastructure
3.10.1 Introduction
3.10.1.1 Details of other infrastructure forming part of the Project and/or representing
enhancements/mitigation are also presented in Chapter 4, Project Description. In order
to develop some of these designs, assessments and feasibility studies have been
undertaken in the fields of art, education, mariculture, and sporting and recreational
opportunities, all centred on the Lagoon which is integral to the Project. Consideration of
the potential options and opportunities are summarised below. These elements are
important in fitting the Project into its environment, and in terms of off-setting the
consequences of impounding an area of Swansea Bay.
3.10.2 Sports and recreation
3.10.2.1 TLSB carried out a feasibility assessment for potential sporting opportunities founded on
the Lagoon, at both local and community level, and to national and international events.
To gain a better understanding of this potential, the assessment first considered the
need and demand for the various sporting opportunities around Swansea Bay.
3.10.2.2 A study was carried out looking at the “requirements for various sports” if located within
the Lagoon. In addition to this, feedback was sought from local residents, liaising with
local universities, colleges and schools, and working with existing local watersports clubs
and the individual national federations of potential core sports.
3.10.2.3 Subsequent to this, an analysis was undertaken of core sports capable of using the
Lagoon, taking into account the level that the sport could be undertaken at, local
opportunities for events, and the facilities required to support that sport.
3.10.2.4 From this work, key sports were chosen as follows:
a) Sailing opportunities: The opportunities for sailing are considerable in the Lagoon,
from grassroots participation through to high performance events. A study was
Tidal Lagoon Swansea Bay plc
Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 36
made into the potential for the site to host Extreme Sailing events. These World
Series events would be the largest and most high-profile sports events hosted on
the Lagoon and would attract the world’s best sailors. The required racing area is
small (minimum of 800m by 200m) and the Project could offer excellent
accommodation and views for spectators.
b) Open water swimming: This sport has increased significantly in popularity in recent
years. Swim Wales is currently developing a bid to become the first “UK Indoor and
Open Swimming Competition and Training facility”. Events of this nature in the past
have been subject to fluctuations in weather conditions, tides and wind force. It is
thought that the Lagoon, with its seawalls providing shelter, would make the
cancellation of events less likely. A number of emergency access points around the
Lagoon walls would need to be incorporated, and disability accesses could also be
created. Further information on water quality within the Lagoon is discussed in
Chapter 7, Marine Water Quality.
c) Triathlon: Triathlon is one of the fastest-growing sports in the UK. In 2011, there
were 140,000 triathlon race starts with an estimate of 70,000 people taking part
nationally. The Lagoon’s safe, sheltered waters could be excellent for all levels of
this sport. During the study, it was evident that Wales is in need of further leading
international venues and that the Project facility has the potential to be a suitable
venue.
d) Rowing: The Lagoon could have the potential to host both international and national
coastal rowing events encompassing all levels of participation. In addition, the site
could become a leading UK training facility throughout the year. There is an
opportunity to provide an excellent area for spectators to view such events in a
unique and complementary setting.
3.10.2.5 The Swansea Bay area is also known to be popular for recreational fishing. For this
reason, the opportunity to provide platforms and access on the seawall for recreational
fishing was also considered important.
3.10.3 Mariculture opportunities
3.10.3.1 A key aim for the Project would be to provide input to the marine environment initially at
a conservation level, but potentially in the future for individual or commercial interests.
Central to this is facilitating the regeneration of the native oyster within the Bay. In
addition to this, the Lagoon seawall will form a new, artificial, rocky reef which is
predicted to be of ecological benefit (Chapter 8, Intertidal and subtidal benthic ecology).
Careful consideration of materials and detailed design of the seawall would provide a
range of habitats which would be colonised by local marine species.
3.10.3.2 In order to develop a better understanding of the concepts around this area, SEACAMs3
undertook research into the feasibility of different opportunities available for
mariculture. Table 3.5 shows the options considered and the current thoughts for
inclusion within the Project.
3 SEACAMS, a project part-funded by the European Regional Development Fund through the Welsh Government is a
partnership between Bangor, Swansea and Aberystwyth Universities. SEACAMS aim is to integrate research and business
opportunities in the marine sector in Wales.
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Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 37
Table 3.5 Assessment of potential mariculture opportunities
Option Initial assessment Potential
Oysters The SEACAMS assessment concluded:
a) There are currently rudimentary oyster
beds present in Swansea Bay.
b) Settlement of oyster larvae occurring
naturally in the water column could be
encouraged by providing suitable
settlement material (cultch).
c) Natural and artificial materials could be
tested as possible cultch, in particular large
amounts of molluscan shell material.
d) The success of settlement will depend on
availability of oyster larvae, and is
suggested that further research to establish
the current presence and abundance of
larvae should be undertaken.
e) Spatting ponds inside the Lagoon stocked
with local oysters could be a realistic
prospect for generating large numbers of
larvae and spat for the wider bay. However,
it would not be recommended to introduce
stocks from non- local hatcheries as this
would introduce a biosecurity risk.
The encouragement of the native oyster
through spatting ponds would be great
opportunity for Swansea Bay as a whole,
and would complement other projects
within the Bay. With this in mind,
discussions have been undertaken with
SEACAMS to take this opportunity
forward. Research is currently ongoing
with respect to existing oyster larvae
levels and current condition of oyster
within the Bay. Details of the
requirements of spatting ponds and
their location within the Lagoon have
been integrated into the masterplan. A
10-year project plan is being developed.
Lobsters Lobsters are present around the coast of Wales
and they tend to prefer rocky habitats. Within
the Swansea Bay area, good rocky habitat is
present around the Mumbles headland. In
addition, lobsters can be found associated with
diffusers on long sea outfalls. There are a few
outfalls in the Bay where lobsters may be
present.
The Project would provide further habitat for
lobsters, through the new reef, but to increase
this opportunity a hatchery could be
considered.
The Centre for Sustainable Aquaculture
Research (CSAR) has extensive
experience and knowledge of running a
hatchery and rearing a range of species
including lobsters. A hatchery has been
integrated into the Project such that this
element of the Project can be taken
further. In addition to this, opportunities
to rear native marine fish species would
also be considered in the future.
Porphyra
(laverbread/Nori)
The collection of Porphyra around the UK is
small and localised.
However, on a wider scale, it is most well
known as a South East Asian foodstuff,
particularly Nori which is often used to combine
fish and rice in a distinctive and attractive
casing. Demand from Japan remains high, and
to meet this requirement Porphyra farming and
processing systems have replaced foraging of
natural stocks.
This relatively modest demand for
Porphyra in the UK appears to be easily
supplied by the large and predominantly
rocky Welsh coastline.
In the wider context, the process of
Porphyra farming is quite complex, with
the needs met through the SE Asian
market.
From the commercial point of view, it is
not proposed to take this opportunity
further.
Kelp and biofuel Kelp is a large seaweed which grows on a stype
attached to a rocky/hard surface around the
low water spring tidal mark.
A variety of research has suggested that Kelp
and other seaweeds could be grown and used
for biofuel production in the future. This would
The development of alternative sources
for fossil fuels is important, as a whole.
However, in terms of the Project it is
considered that development of the
seawall for kelp harvesting would
conflict with its biodiversity
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Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 38
Option Initial assessment Potential
be a good source for biofuels as it grows quickly
and does not compete with food production
like land-based biofuel crops do. However,
there have been difficulties in cultivation and
harvesting kelp and it has not yet been cost
effective.
The suitability of the kelp's chemical
composition also varies on a seasonal basis so
the seaweed is best harvested in the summer.
However, even with this seasonal consideration
it could be a viable biofuel in the future, even
more so with rising oil price. Other options
could also be considered, for instance first
extracting higher-value products from the
seaweed such as food additives or protein for
fish food before converting the remainder to
bio-fuel.
enhancement objective. As such, this
opportunity will not currently be taken
forward for the Project.
Community allotments The concept of a community farm or allotments
is well known and well practised around the UK.
To bring a new slant to this idea, marine
community allotments are being considered.
At this stage of the Project, it has been
decided to focus on a few key elements
to enhance the ecology of the Bay as a
whole, and which can be secured
through existing links with
SEACAMS/CSAR. As such, at present,
community allotments will not be
progressed, but they may be considered
sometime in its future.
Education and Art
3.10.3.3 Cape Farewell was appointed as TLSB’s education and cultural partner in early 2012.
TLSB believes education is a very significant part of this Project and its legacy, and it is
committed to lead wholehearted collaboration in reducing carbon, delivering low-
carbon green electricity and serving our communities.
3.10.3.4 To facilitate this, TLSB created an education programme and resource for the schools
and colleges of Swansea and Neath Port Talbot. The programme is aimed at helping
young people develop their skills and knowledge, so that they can make their own
choices for the future environment.
3.10.3.5 An education officer has been appointed to assist schools in the implementation of
workshops, and an ongoing programme has been established to widen the scope of the
resource and ensure all levels of education are encompassed.
3.10.3.6 TLSB also aims to strengthen the understanding and exploration of community values
and the environment to increase stakeholder involvement in the development. To aid in
this TLSB has established an art programme to create a forum for artists, scientists and
communicators to be brought together to stimulate the production of art founded in
scientific research.
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Tidal Lagoon Swansea Bay – Environmental Statement
Site Selection and Option Appraisal Page 3- 39
3.10.3.7 Future creative educational features and topics being considered for inclusion within the
visitors centre and around the Lagoon wall include:
a) Looking at the Honeycomb Worm (Sabellaria alveolata): This is a UK Biodiversity
Action Plan species found in areas within Swansea Bay and along the Welsh coast. It
is a frequently gregarious segmented worm that builds tubes from sand or shell
fragments. It is found inter-tidally (although occasionally sub-tidally) in exposed
areas, and the tubes created by this species are often densely aggregated forming a
honeycomb pattern. These honeycomb structures could be located around the
Lagoon wall as an art and education feature.
b) An historic art trail depicting the story and future hopes for an oyster industry:
Swansea Bay was famed for native oyster species from the 1600s through to
Victorian times. The oyster industry went into decline in the late 1870s due to over-
fishing and then disease wiped out stocks in the early 1900s. The last Oyster skiff
was retired in the 1930s. Ideas are being investigated to reinstate oysters in the
Bay.
c) Information on fish species: rays/skates (elasmobranches) have a firm tradition in
Wales, though it has declined in recent years. Further information on their biology
and shape, as well as on other fish species caught in the Bay could be provided along
the lagoon seawalls.
d) Schools art: areas could be allocated along the Lagoon wall for murals made from
pottery tiles from different schools depicting what Swansea Bay means to them.
3.11 References
DECC 2009, UK sOffshore Strategic Environmental Assessment (available at
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/19538
7/OESEA2_NTS.pdf)
DTI 2007, Strategic Environmental Assessment Area 8, superficial seabed processes and
hydrocarbon prospectivity (available at
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/19701
1/SEA8_TechRep_SeabedProc_HCProspect.pdf)
The Crown Estate 2012, UK Wave and Tidal Key Resource Areas Project (October 2012)
Summary report. http://www.thecrownestate.co.uk/media/355255/uk-wave-and-tidal-
key-resource-areas-project.pdf
Williams, Robert 2011, “How France eclipsed the UK with Brittany tidal success story”
http://www.theecologist.org/News/news_analysis/678082/how_france_eclipsed_the_u
k_with_brittany_tidal_success_story.html.