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EJR/EJR/343641/1/UKM/62783439.1 1
CONSTRUCTION PROCESS, DREDGING AND PHYSICAL PROCESSES
Construction Process
3.1 to the Applicant
Table 4.1 of the ES is provided to describe the design options under consideration.
However by comparing the description of the development in Chapter 4 with this
table, not all of the construction options are included in this table.
Please could the applicant provide an updated table, which clearly sets out all of the
options under consideration, including details identifying which of these options
have been assessed in the ES and where applicable, evidence to justify the ‘worst
case’ adopted for the purposes of the assessment?
TLSB's Response
1. An updated version of Table 4.1 is provided at Appendix 3.1.1.
2. Please see also a related note dealing with the comparison of lagoon seawall
construction methodologies of Geotubes® or quarry run at Appendix 3.1.1.
EJR/EJR/343641/1/UKM/62783439.1 2
3.2 to the Applicant
A number of methods for constructing the sea-wall are described in the ES (Project
Description, paras 4.3.1-4.3.4) and illustrated in Figures 4.4-4.6. It is explained that certain
sections of the sea-wall will require certain construction methods, for example the inclusion
of a rock-armour crest for health and safety reasons.
(a) Please could the applicant provide a figure (drawn to scale), which illustrates
where each of these sections is proposed to be located?
TLSB's Response
1. Drawings 2.2.11, 2.2.12 and 2.2.13 of the Works Plans submitted with the
Application (doc ref 2.2) show 10 cross sections at intervals along the seawall.
Each of these cross sections is designed to the specific criteria in terms of usage,
and to the specific ground and wave conditions for that location. All sections have
a rock armour crest and a concrete wave wall. The rock armour size and height,
and design of the concrete wave wall, increase in size in those locations where the
wave action is more severe (e.g. compare section 2 and 3 to section 1 on drawing
2.2.11).
(b) Paragraph 4.3.1.7 explains that the seawall will be constructed to absorb 60-
70% of wave energy. How will this design requirement be incorporated into
the DCO?
TLSB's Response
2. The energy absorption capability of the seawall depends on the local wave
conditions; on the steepness of the outer armour rock slope; and on the thickness
and porosity of the main rock armour. The design for each of the seawall sections
is shown on Drawing 2.2.11, 2.2.12 and 2.2.13 of the Works Plans (doc ref 2.2).
The wave reflection is calculated for these sections (using the methodology
outlined in the Rock Manual1 which gives a reflection coefficient between 0.2-
0.3, meaning an absorption of the wave height of 70-80% and an absorption of the
wave energy of more than 90% (Note: wave energy is relative to the wave height
squared). The wave reflection was validated and confirmed for the most exposed
section through physical model testing in HR Wallingford.
3. This design requirement (i.e. absorption of 60 to 70 percent of wave energy) is a
natural consequence of using rock as armour for the seawall structure. It is
incorporated into the requirements of the DCO by the inclusion of drawings
2.4.19 to 2.4.21, the designs in which must be implemented in order to comply
with Requirement 5 of Part 3 to Schedule 1 of the draft DCO. If an alternative
design is proposed, it would require the prior approval of the relevant local
planning authority under the terms of requirement 4, a revised version of which is
submitted with these written representations.
1 Chapter 5, CUR/CIRIAC683, 2007
EJR/EJR/343641/1/UKM/62783439.1 3
(c) How has this design been incorporated into the coastal processes modelling?
TLSB's Response
4. In the coastal processes modelling conservative reflection coefficients (0.3) have
been used.
5. In general the reflection from a seawall depends on the wave conditions and
structure parameters. Details on how to calculate the reflection can be found in the
Rock Manual (e.g. equation 5.73).
6. Eastern breakwater: In calculating the reflection for the eastern breakwater (slope
1:2.25) an average reflection of around 0.3 is obtained. This reflection coefficient
was confirmed by HR Wallingford using a physical model where values between
0.2 and 0.4 where found among a range of swell wave conditions.
7. Western breakwater: The western breakwater has a slope of 1:2. With a
computed local wind wave of Hs=1.2 and Tp 3.2s, a reflection of 0.2 is obtained.
No physical modelling was undertaken for the reduced slope of the western
breakwater but, within the modelling to support the EIA, a conservative reflection
coefficient of 0.3 was used.
8. The design of the seawall and the wave reflection has been incorporated into the
coastal process modelling using a 0.3 reflection co-efficient for the seawall, which
is considered a conservative approach.
EJR/EJR/343641/1/UKM/62783439.1 4
3.3 to the Applicant
Paragraph 4.3.1.11 of the ES (Project Description) states that rock armour will be
placed on the sea-wall, 'at a greater height' to allow for settlement.
(a) What is the maximum extent of the 'greater height'?
TLSB's Response
1. The total settlement was calculated for seven representative sections of the
seawall. The maximum total settlement is calculated at 1.3m for the deeper part of
the western seawall (section 2 on drawing 2.2.11 of the Works Plans - doc ref
2.2). The largest proportion of the calculated settlement will occur during
construction (typically about 80%). A smaller proportion will occur after
completion (i.e. post-construction). During construction, no use will be made of
preloading the bund wall to accelerate settlements. The ‘greater height’ referred to
at paragraph 4.3.1.11 applies to settlement compensation alone.
(b) How much settlement is expected? and;
TLSB's Response
2. The post-construction settlement for the western seawall is 275mm. The average
post-construction settlement for the eastern seawall is 130mm. The final
construction level of the western bund wall will thus be 275mm higher than the
design level to allow these post-construction settlements to take place without
affecting the safety against wave overtopping.
3. These figures are rendered as precise, calculated figures. In fact, the post
construction settlement can be seen to be modest in extent, and will (of course) be
dependent on local conditions so as to vary to some amount within appropriate
engineering tolerances.
(c) Over what timescale is the settlement expected to happen?
TLSB's Response
4. The settlement during construction take place over an average time period of three
years. The post-construction settlement is calculated for a 50 year period. The
general trend is logarithmic, meaning that most of the post-construction
settlement will take place in the first few years after completion. For the
maximum calculated settlement (western seawall) of 275mm after 50 years, about
190mm will take place in the first three years after completions. Ten years after
completion the calculated settlement will be 230mm.
EJR/EJR/343641/1/UKM/62783439.1 5
3.4 to the Applicant
Paragraph 4.3.1.8 of the ES (Project Description) refers to an 'engineered toe'. No
description of this is provided; it is not known what construction and engineering
requirements will be necessary to provide the 'engineered toe'.
Please can the applicant provide a design drawing showing the engineered toe as
well as a plan showing where it will be required and details explaining how it will be
constructed?
TLSB's Response
1. Drawings 2.2.11, 2.2.12 and 2.2.13 of the Works Plans (doc ref 2.2) show ten
cross sections along the seawall. The engineered toe is shown on each of the
sections, both on the seaward side and on the lagoon side – effectively, the term
refers to the toe structure of the seawall in all locations for this Project. The main
function of the toe structure is to support the armour on the front and rear slopes
of the seawall, and to provide safety against undercutting and localised erosion.
2. In general, the seaward toe structure consists of a 3 to 4 metre horizontal
extension of the primary and secondary rock armour layers, placed on a heavy
(weighted) geotextile. The rock dimensions are determined based on stability
under governing wave attack for each of the sections. For the most exposed
section this has been confirmed in 2D physical modelling. To prevent loss of base
material, a geotexile is placed to prevent sand escaping through the pores of the
rock. The lagoon side toe structure has a reduced width of 2 metres which reflects
the smaller waves inside the lagoon.
3. The toe will be constructed as part of the front and rear armour placement.
Typically, the geotextile under the toe is placed as part of the geotextile placement
on the Geotubes® (as described in paragraph 4.5.3.22 of the ES) and is
subsequently covered by one or multiple rock layers as shown on the works plans
noted at paragraph 1 above. The rock placement will be done by either side stone
dumping or placement by crane, depending on the local depth.
EJR/EJR/343641/1/UKM/62783439.1 6
3.5 to the Applicant
Paragraph 4.3.3.15 (Project Description) confirms that the gantry crane will sit
above the turbine housing unit, however, it is anticipated that the roof of the unit
will be raised and the crane housed internally. The dimensions of the internal
enclosure are not provided in the ES.
(a) How and where has this part of the construction process been incorporated
into the ES in terms of impacts?
TLSB's Response
1. Paragraph 4.3.3.15 of the ES states: “Figure 4.17 shows an external gantry crane
above the turbine housing structure. However, it is anticipated that the design
will be developed to raise the roof and have an internal crane with much reduced
height.” In this context, it is important to note that the statement "raise the roof" is
not a construction process, but a proposal that the roof height be greater than
shown in the application drawings. Otherwise, the general dimensions of the
structure are unaffected. The revised arrangements of craneage are shown on
drawing TLSB-260614-V0.1 at Appendix 3.5.1 to this response.
2. This is capable of being achieved within the submitted application since the
powers in article 3 and part 2 of Schedule 1 to the draft DCO enable a maximum
height for Work No. 2a of +18.5m CD. The submission of an alternative drawing
is permitted under Requirement 4 in Part 3 of Schedule 1 to the draft DCO. It is
expected that this would result in the substitution of plans bearing application
references 2.2.13 (Works plan) and Planning Drawings 2.4.25-.27. It is intended
that substitute drawings are supplied at ExA deadline 3.
3. The relationship of these proposals to the application and assessments recorded in
the ES is described below.
Main turbine gantry crane and housing
4. The main turbine gantry crane referred to in the Application will now be located
under the roof of the turbine housing which is an integral part of the turbine
housing structure. This will reduce corrosion in the marine environment and allow
some maintenance work inside the turbine housing void, thus improving
operational efficiency. The roof top level above the internal gantry crane is, as
shown in appendix 3.5.1, at +17m CD. This accords with the heights considered
in the visual impact assessment, which is dominated by the size of the offshore
visitor centre (roof top level at +33.5m CD) and which was based on a +16.5m
CD structure with up to 2m upwards deviatoin. As such, the assessment of this
structure is already included in the ES.
Other craneage
5. The turbine tender process and ongoing electrical and mechanical (E&M) design
work for the Project has further updated the craneage requirements since
submission of the Application. This work shows that – while one crane will be
incorporated into the turbine housing structure as described above – other gantry
cranes are still required which must be mobile and external to the turbine housing
EJR/EJR/343641/1/UKM/62783439.1 7
roof. These are required for periodic maintenance purposes: to insert stop logs
(that allow work to occur within a dry turbine chamber); and/or to lift turbines,
start/stop gates, sluice gates or other components requiring servicing. The general
arrangement and top levels of these external cranes is shown on the drawing
attached at Appendix 3.5.1.
6. The top level of these mobile external gantry cranes, as now proposed, varies
from +19.2m CD to +24.2m CD and as such they are smaller than the original
main gantry crane assessed at a height of ~+27.5m CD with a power to deviate
upwards of 2m. The visual impact of these cranes falls within the envelope
considered in the ES supporting the Application, albeit the number of external
cranes has now increased from two to a maximum of four - see appendix 3.5.1.
7. A comparison of the designs from Application to date is shown in the table below:
Lifting
device/purpose
TLSB – submitted design
for Planning Application
(top level)
Present design
(top level)
Turbine
maintenance
Multi-purpose main gantry
crane (+27.5m CD) or;
Internal gantry crane (not
shown)
Internal gantry crane
(+17m CD roof top level)
Turbine
start/stop gates
Not included Internal cylinders for
daily operation (+17m
CD top level).
For maintenance:
External Gantry Crane 1
(+24.2m CD)
Turbine stop
logs
Assumed to be a mobile
crane to be mobilised from
Swansea as and when
needed
External gantry crane 1
(+24.2m CD) – sea side
External gantry crane 2
(+22m CD) – lagoon side
Maintenance
Island - crane
Gantry crane (+27.5m CD) External Gantry crane 4
(+27.5m CD)
Main sluice
gates
A-frame hoist (+16.5m CD,
as per drawing 2.4.26 in
Folder 2, Volume 4).
Internal cylinders for
daily operation (+16.5m
CD top level).
EJR/EJR/343641/1/UKM/62783439.1 8
For maintenance: assumed
to be a mobile crane to be
mobilised from Swansea as
and when needed
For maintenance:
External gantry crane 3
(+19.2m CD)
Sluice gate stop
logs
Assumed to be a mobile
crane to be mobilised from
Swansea as and when
needed
External gantry crane 3
(+19.2m CD)
8. The table above shows the worst case. If possible, the additional, specialised
cranes 1 to 4 described above will be combined into fewer general-purpose
crane(s), which will remain within the required parameters. When not in use, the
crane(s) will be stored on the turbine and sluice gate dividing structure
(maintenance island).
9. Although there may be more cranes than originally anticipated, these will all be
located together in the same general area. In terms of heights, as identified in the
table above, the cranes are all considerably lower than the original proposed
gantry crane, ranging from around 4.5m to 11.7m above the seawall (17m –
24.2m above CD). The cranes would be black/grey in colour (as stated in the ES),
slender, and can be stored together, thereby minimising potential effects.
Notwithstanding this, a further review of the potential effects from relevant
viewpoints has been undertaken and is provided below.
Verification of assessment
10. The SLVIA allowed for an assessment of a turbine and sluice gate dividing
structure that included an external semi-goliath gantry crane. The worst case now
proposes to include the following cranes: 1no. internal gantry crane; and up to
4no. mobile external gantry cranes.
11. Within the ES, a Zone of Theoretical Visibility (ZTV) was undertaken
incorporating the largest block structures of the Project. For the offshore area this
was the Offshore Building. Within the ZTV the following heights as described in
Chapter 4 of the ES (para 4.3.5.9 and para 4.3.5.22) were assumed:
Offshore Building - 25.5m above the Lagoon seawall; and
Western Landfall Building - 13.5m above the Lagoon seawall.
12. As identified in Chapter 4 at paragraph 4.3.1.11, the permanent level of the top of
the rock armour along the most exposed sections is +13.5mCD (Chart Datum), as
shown on Figure 4.4, falling to +13mCD for a section adjacent to the Neath
Channel and will be +12.5mCD for the sections of the seawall approaching
landfall on both sides, shown on Figure 4.5.
EJR/EJR/343641/1/UKM/62783439.1 9
13. The actual height of the offshore building will be 33.5m above CD, as such the
ZTV was based on a larger “envelope” than that actually proposed for the
offshore Project structures (namely 36m above OD, see Figure 13.05 of the ES)
and a worst case ZTV has been prepared and used for the SLVIA. As the cranes
would be slender plant items, which could be moved around, they were not
included in the ZTV block, but reference was made to them in consideration of
effects upon relevant viewpoints throughout the discussion within the SLVIA
chapter of the ES (Chapter 13).
14. The SLVIA (Chapter 13 of the ES) identifies that, from the 22no. viewpoints
assessed, the turbine and sluice gate dividing structure and semi-goliath gantry
crane would potentially be a feature of views from the following locations:
Viewpoint 1 - Aberavon Sands, South
Viewpoint 2 - Aberavon Sands, North
Viewpoint 4 - Headland Road, St. Thomas, Swansea
Viewpoint 5 - The Knab, Adjacent to Mumbles Pier
Viewpoint 6 - Mumbles Hill Nature Reserve
Viewpoint 7 - Swansea Promenade, near Lido
Viewpoint 8 - Clyne Golf Course, Swansea
Viewpoint 9 - Nicander Parade, Townhill, Swansea
Viewpoint 10 - Meridian Quay, Swansea
Viewpoint 11 - Swansea Promenade
Viewpoint 13 - Kilvey Hill, Swansea
Viewpoint 16 - Swansea University Science and Innovation Campus
Viewpoint 18 - PRoW on Mynydd Brombil
Viewpoint 19 - Swansea Bay
Viewpoint 21 - Pant y Celyn Road, Townhill, Swansea
Viewpoint 22 - Clyne Gardens, Swansea
15. Following the introduction of further, mobile gantry cranes to be located mainly
on the dividing structure, it is predicted that they will be viewed as an additional
element, most noticeably from close distance views including locations within
Swansea Bay (Vp19), on Swansea Promenade (including VP7 and VP11), The
Mumbles (VP5) and Meridian Quay (VP10). They may also be noticeable from
elevated locations including Kilvey Hill (VP13) and the areas of St. Thomas
(VP4) and Townhill (VP9 and VP21), both within Swansea. However, they are
predicted to be viewed in conjunction with the Offshore Building as opposed to as
isolated features.
16. From other, more distant locations, the additional cranes will be minor elements
of the view. It is concluded that, although visible, the introduction of further
cranes and any subsequent additional effects on visual amenity as a result of their
introduction into the landscape/seascape, beyond those currently identified within
the SLVIA within the ES, will not be to an extent that will affect the conclusions
of that assessment, which still stand.
EJR/EJR/343641/1/UKM/62783439.1 10
(b) Please could the applicant explain how this design aspect will be secured in
the DCO?
TLSB's Response
17. The form of the turbine house, including craneage is secured by Requirement 5 of
the DCO, which requires construction of the Project in accordance with the plans
that it lists. These include the drawings with reference 5118483-ATK-02-ZZ-DR-
C-1110, 1208, 1209 and 1213.
18. If and to the extent that it is proposed to construct the Project other than in
accordance with the above drawings, the details of any alternate design must be
approved in advance of construction by the relevant local planning authority. The
mechanism for this is secured by requirement 4, for the revised wording of which
please refer to the Response to Written Question 3.2b.
EJR/EJR/343641/1/UKM/62783439.1 11
3.6 to the Applicant, MMO and NE
The ES includes a description of temporary work required to facilitate the construction
of the development (Section 4.5 (of the Project Description onwards)). The draft DCO
does not appear to refer to some of the aspects of the temporary construction works, (for
example, lay-down areas, material handling facilities, demolition of sea walls and
existing development and concrete crushing etc.)
(a) Please can the applicant provide a list of work processes and areas that will
be included in the 'temporary works' and confirm (by cross referencing the
work processes and areas to the relevant sections of the ES) that all aspects
have been assessed in the ES.
TLSB's Response
1. Section 4.7.7 in Chapter 4 of the ES describes the temporary elements associated
with construction of the Project, and identifies a number of potential construction
site locations for possible use (Figure 4.56 of the ES and re-produced below.) The
areas shown in the figure allow maximum appropriate flexibility for siting of
facilities for the construction phase. The boxed areas illustrate the sizes required,
although only one compound of each type of area would be required.
2. The construction masterplan at Appendix 3.9.1 shows the areas that are being
considered for the activities described below.
3. The areas are as follows and are described further in the relevant paragraph in
Chapter 4:
i. Area A - offices, stores, car parking, site access control and plant yard.
Requires an area of approximately 26,000 m2 (260m x 100m or equivalent)
(paragraphs 4.7.7.5 – 4.7.7.7, Figure 4.57)
ii. Area B - concrete batching plant, stockpiling area and pre-casting yard.
Requires an area of around 17,000m2. Two possible locations have been
identified. (paragraphs 4.7.7.8 – 4.7.7.10, Figure 4.58)
iii. Area C - steelwork fabrication yard. Requires an area of approximately
22,500m2. Two possible locations have been identified. (paragraph 4.7.7.11,
Figure 4.59)
iv. Area D - storage yard. Requires an area of approximately 62500m2 (625m x
100m or equivalent). Two possible locations identified. (paragraph
4.7.7.12).
EJR/EJR/343641/1/UKM/62783439.1 12
3. This temporary land requirement for construction has been included in the
assessment on terrestrial ecology presented in Chapter 12 of the ES, at sections
12.5.3 “Potential construction impacts, mitigation and residual impacts” and
12.5.4 “Potential construction impacts on key ecological receptors”. The
assessment has been informed by site-specific surveys undertaken for the Project.
Further information on this survey work is provided in the Technical Appendix to
Chapter 12 of the ES, sections 12.2 – 12.8. The area surveyed cover the areas
being considered for use during the temporary construction phase.
4. Lay down areas would be provided on an ad hoc basis where and when required
within these compounds or elsewhere in the Order limits. Activities in such areas
would include: loading and unloading of vehicles; storage of materials; vehicles
and plant parking; storage of small plant and containers for small tools; and are
not predicted to be environmentally intrusive.
Rock storage
4. Rock storage areas for rock armour delivered by sea will be required to allow
flexibility in the work programme, and to make allowance for varied weather
conditions. This approach means that a buffer of rock supplies can be established
so that construction may continue even if access to the Project or from the
quarries is precluded for reasons such as adverse weather conditions. Further
information is provided in TLSB's Response to Written Question 3.18. See
drawing at Appendix 3.9.1 where these areas are shown on an OS based map.
5. Chapter 4 of the ES, paragraph 4.5.3.24, states that “The stockpiles would be
located near the landfalls at both sides of the Lagoon. The stockpile adjacent to
EJR/EJR/343641/1/UKM/62783439.1 13
the western seawall would be approximately 400m by 400m and piled up to 3m
high. The stockpile adjacent to the eastern seawall within the lagoon would be
approximately 250m by 250m in area and piled up to 3m high”.
6. These stockpiles will be located in the intertidal area adjacent to the area of the
construction works at the Western landfall and Eastern landfall, within the
Lagoon footprint. This is shown on Plan 1117:WMp:001 at Appendix 3.9.1. The
rock will be stockpiled to a height of 3m above Chart Datum.
7. The loss of this habitat is included in Table 4.4a of Chapter 4, which shows that
the loss of intertidal area as a result of these rock stockpiles between year 1 and 3
of construction will be approximately 22.25 ha. The positioning of the western
rock storage area would fall within the area used for the western landfall
facilities/boating centre, thereby minimising impacts. For the eastern landfall
rock storage area, once operational this intertidal area is predicted to re-colonise.
Onshore construction access and routeing
8. Road access to the Project for construction traffic will be via Fabian Way from
the traffic light controlled junction opposite the Park and Ride shown on plan
2.4.38 and then through the Port. For the western landfall, the access route will
follow the permanent proposed Project access road. It is expected that deliveries
will use the M4 and followed by the A483 (Fabian Way) to reach the Project site.
This is as assessed as part of the study area set out in paragraph 15.4.1.2 of the
ES.
9. For the eastern landfall, the road access will follow the same route; however, once
at the existing shoreline in the vicinity of the existing Swansea Port security gate,
a temporary track will be constructed across brownfield land (a former BP tank
farm), seaward of the existing sea wall, and across intertidal land to the south of
SUBC. This construction access to the eastern landfall will run along the
southern strip of the old tank farm behind the existing rock armour and concrete
retaining wall.
10. Construction Phase Travel Management Plan ("CTMP") (a draft of which is
included at Appendix 15.12 of the ES and also annexed to the draft CEMP) will
govern deliveries to the site. The final version of the CTMP will be approved by
the relevant local planning authorities under the terms of Requirement 6 annexed
to the DCO.
11. The on-site construction access routes are shown in Figure 4.60 below.
EJR/EJR/343641/1/UKM/62783439.1 14
12. For routine site deliveries all delivery wagons will access the site as indicated
above. Abnormal deliveries will be planned to ensure the Baldwins Bridge access
is clear, if necessary a holding location will be agreed where the delivery vehicles
will wait until they are required. If a large amount of deliveries are expected over
a short period (e.g. turbine elements) these will be planned to ensure that only a
certain amount arrive at site at any one time, again the holding location can be
used to control this.
13. As stated in paragraph 12.5.3.8 “Other construction activities, for example,
development of the seafront beside the Queens Dock for an access road, would
result in disturbance of coastal grassland and scrub communities, whilst
potentially enhancing the ecological value of land currently largely devoid of
interest (with the exception of localised populations of species such as Golden-
samphire) due to the presence of rock armouring and concrete. In addition, a
haul road aligned along the existing coastal edge will be constructed between the
docks and eastern landfall. Ultimately, the haul road will be become enveloped
within an artificial dune front although part of it will be re-used as a cycleway.”
Demolition of the seawall
14. Demolition of the existing port sea walls is a work, shown in the Planning
Drawings at 2.4.41 – 2.4.44, which comprise demolition plans.
EJR/EJR/343641/1/UKM/62783439.1 15
15. As identified in paragraph 4.3.7.8 of the ES “The proposed Project road will
extend along the south side of the Queen’s Dock and utilise the alignment of the
existing Port road. The majority of the existing 2m high concrete flood wall will
be removed to open up views to the Lagoon, this is shown in Figure 4.37 below.
Where there are existing World War II features, such as pill boxes, these
structures will be retained, along with a 3m section of wall either side, shown on
Figure 4.38 below. More information on these features can be found in Chapter
21, Cultural Heritage: Terrestrial Archaeology and Historic Landscape.”
16. As identified above, these works would be adjacent to the Project road works and,
as such, the extent of impacts will be minimised. Further information on
additional plant such as crushing plant is provided in TLSB's Response to Written
Questions 3.17, 10.14 and 10.15. The timing of the removal of the seawall would
be programmed such that coastal protection within the Port is maintained.
(b) Does the DCO require amendment to refer to these temporary works?
TLSB's Response
17. It is suggested that the draft DCO does not refer to all aspects of the temporary
construction works for the Project. In particular, this includes lay-down areas,
material handling facilities, demolition of sea walls and existing development and
concrete crushing.
18. Some of the items listed are not themselves works, being demolition. That would
apply to demolition of existing sea walls and "existing development." These are
provided for in article 3(2) which includes "decommissioning and demolition of
any buildings or other structures within the order limits to the extent they relate to
are required by or are incidental to the carrying out of the authorised
development." Further, such works are controlled by Requirement 5 and plans
2.4.41-2.4.44.
19. In respect of the other items it would be possible to include a list of temporary
works expanding schedule 1 to the development consent order to include those
identified in the ES, should this assist the Examining Authority. However, the
extent of the works in question does not require them to be identified as scheduled
works.
EJR/EJR/343641/1/UKM/62783439.1 16
3.7 to the Applicant
The ES Chapter 4 (Project Description) identifies that piling is likely to take place
offshore during the construction of the cofferdam that is required for the turbine
and sluice-gate housing, as well as to create the dolphin piles that are proposed to
surround the outer edge of the lagoon in the vicinity of the turbine and sluice gates.
(a) Is piling proposed to take place in any other location?
TLSB's Response
1. As stated in the submission in respect of the construction of the temporary
cofferdam, submitted to the Examining Authority in June 2014, TLSB now
intends only to pursue seawall construction techniques using a sediment-based
berm with Geotubes® as a method of constructing the cofferdam. It no longer
proposes construction of a twin wall sheet piled cofferdam. Therefore, piling of a
cofferdam structure as described in the ES will no longer be required for this part
of construction, with a commensurate and material reduction in piling activity.
See paragraphs 4.5.3.35 - 4.5.3.38 of the ES for more detail on the preferred
method.
2. Nevertheless, a slurry wall will still need to be piled into the temporary bund for
the now-proposed method of construction. This wall will be installed from and
through the top of the temporary bund by vibrating a H-beam into the ground and
pulling it back while jetting grout into the structure. This creates an impermeable
cut-off within the temporary bund wall. In contrast to the piling required for the
sheet pile cofferdam, this piling will require vibration piling only, and, although
offshore, will be undertaken using land based equipment in the dry of the
temporary cofferdam. It will be a 24/7 activity, although the duration will be 6
weeks, rather than 6 months needed for the other (piled) method of construction.
3. Piling is required for the dolphin piles forming the turbine exclusion zone (Work
No.2c). There will be 10 dolphin piles, with piling required for 10-15 days during
daytime hours only. Vibration piling will be used as far as possible, although
there is a small likelihood of percussion piling.
4. A cut off sheetpile will be required at the toe of the turbine house (Work No 2a).
This piling will take place in the dry within the temporary cofferdam. It will take
4 weeks of vibration piling, during daytime hours only.
5. The quay wall of the boating area (Works No. 6a and 6b) will require 1 month of
vibration piling, but percussive piling will be required if hard layers are
encountered. This will be daytime piling only.
6. The boating centre building and hatchery, and the offshore building will both
require 2 weeks of percussion piling using land based equipment. This will be
daytime piling only.
7. A small amount of piling will also be needed for the water shuttle pontoon and the
floating jetty boating are Works No. 9a and 9b. These will both require 2-3 days
of vibration piling, daytime only.
EJR/EJR/343641/1/UKM/62783439.1 17
8. Please see the plan given at Appendix 3.7.1 for further details and locations of all
proposed piling activity.
9. Noise and vibration impacts have been assessed from percussive piling at the
turbine and sluice gate housing structure for both daytime and night-time periods
for onshore receptors and have been shown to have no significant impact. All
land-based piling is proposed to take place during the daytime only, and will use
vibro-piling. In the case of the quay wall boating and boating centre building and
hatchery area, percussion piling may have to be used for the last few metres of the
piles, dependent upon ground conditions. However, an evaluation of potential
noise levels has been undertaken and assessed. Noise from piling will be audible
at some receivers; however, when assessed using BS5228-1, levels at all receivers
would be below the fixed noise limit criterion.
(b) If so, please could the location be shown on an OS based plan, together with
the provision of details of the likely duration of the piling, the type of piling
proposed and whether the piling will be undertaken 24/7?
TLSB's Response
10. Please see the plan at Appendix 3.7.1.
EJR/EJR/343641/1/UKM/62783439.1 18
3.8 to the Applicant
The ES Chapter 4 (Project Description) identifies that both percussion piling and
vibration piling/piling by jack-up barge using a piling rig are likely to be required,
with percussive methods necessary when harder base rock materials are
encountered.
Have the noise and vibration calculations given in ES Chapter 19 assumed that
piling would be carried out by vibration piling alone?
TLSB's Response
1. Chapter 19 of the ES submitted with the Application assesses both vibration
piling and impact (percussion) piling methods. It is not assumed that vibration
piling alone will be deployed.
2. The assessment for air borne noise and the effects on the terrestrial environment
as a result of piling is provided at paragraphs 19.5.2.12 – 19.5.2.20 of the ES.
Tables 19.19 and 19.20 show predicted day-time and night-time noise levels
arising from impact (percussion) piling activities, and tables 19.21 and 19.22
show predicted day-time and night-time noise levels arising from vibro-piling
(vibration piling) activities.
3. The assessment for underwater noise is provided at paragraphs 19.5.2.27 -
19.5.2.34. Table 19.27 shows source underwater noise levels for both impact and
vibration piling, and Table 19.28 shows predicted underwater noise levels for
impact and vibration piling at a range of distances.
4. The effects on the ecological receptors are discussed in the relevant chapters of
the ES, namely Chapter 9, Fish, including commercial and recreational fisheries;
Chapter 10, Marine Mammals and Turtles; Chapter 11 Coastal Birds; and Chapter
12 Terrestrial Ecology. The chapters use the assessment from Chapter 19, for both
impact and vibration piling, but take into consideration that impact piling will
only be used when necessary.
5. The vibration effects as a result of piling, which takes into account both impact
and vibration piling, are considered at paragraphs 19.5.4.3 and 19.5.4.4.
6. As discussed in response to the previous question the 24/7 piling over 6 months
associated with a sheet-piled cofferdam is no longer proposed to form part of the
Project. The assessment of these impacts, as presented in the ES, was considered
as a worst case. Based on the assessment undertaken, vibro-piling would be
within acceptable levels to fish and marine mammals and no mitigation would be
required. For percussive piling, JNCC standard mitigation measures would be
implemented.
7. As identified in response to Written Question 3.7 above, other offshore piling
activity is proposed, namely the dolphin piles associated with the navigation
safety zone. Ten dolphin piles will be installed over a 10 to 15 day period. The
intention will be to use vibro-piling but there would be a small possibility of
impact piling if necessary. An assessment of the effect of this piling has been
undertaken for fish and marine mammals, as described below.
EJR/EJR/343641/1/UKM/62783439.1 19
Fish
8. Noise calculations have been undertaken for vibro- and impact-piling respectively
for 2 m diameter dolphin piles. In the absence of precise information on piling
locations, the plots have been calculated centring on the turbine housing, but they
could be expected to shift south-westerly by some tens of metres, depending on
final locations. Source levels are as follows:
i. Vibropiling (2m diameter dolphin piles) 205 dB@1m (peak), 190 dB@1m
(rms)
ii. Impact piling (2m diameter dolphin piles) 235 dB@1m (peak), 220
dB@1m (rms)
9. Peak values have been used as worst case, as shown in the table below.
10. Predicted avoidance zones associated with vibro-piling are confined to ranges of a
few tens of metres for salmon, sea trout, eels and epibenthic hearing generalists
(dab and other flatfish, elasmobranchs, gobies etc.). Vibro-piling avoidance
ranges (>75dB) for cod and herring are slightly larger at around 355m and 630m
respectively. Impact piling potential avoidance ranges increase to around 1 km for
less sensitive species and 10km for cod, 17 km for herring.
11. For both vibro-piling and impact piling soft-start procedures will be used for the
first 20 minutes to enable fish to move away before full piling energy levels are
reached. In this way the impact of this piling activity will be minimised.
Marine mammals
12. The following sections address piling impacts relating to marine mammals as set
out in the ES.
13. For the Project, piling activities will generate the greatest levels of underwater
noise. A temporary cofferdam and associated sheet piling is no longer required for
the construction of the turbine and sluice gate housing structure. Instead, ten
tubular dolphin piles of 1.8m diameter will be used to delineate part of the
perimeter of the turbine and sluice gate structure which are estimated to take
approximately 10 days to install.
14. The ground investigation results (provided in Chapter 6 of the ES) suggest that
the most appropriate piling method would be vibratory, but there may be times
when harder material is encountered and in these circumstances percussive
methods may need to be adopted. Percussive piling (which is also referred to as
impact/hammer piling), will generate the highest noise Source Levels (SLs) and,
EJR/EJR/343641/1/UKM/62783439.1 20
therefore, the assessment has focussed on the potential noise effects of this type of
approach in the first instance, on a worst-case basis.
15. Based on these requirements, an underwater noise assessment of the construction
components of the Project was carried out to assess the impacts on grey seal and
harbour porpoise. The un-weighted peak and Root Mean Squared (RMS) SLs
from vibro-piling and impact piling measurements of 2m tubular piles, which is
the approximate diameter of the tubular dolphin piles proposed, were derived
from a review undertaken by the California Department of Transport.
i. Vibropiling (2m diameter dolphin piles) 205 dB@1m (peak), 190 dB@1m
(rms).
ii. Impact piling (2m diameter dolphin piles) 235 dB@1m (peak), 220
dB@1m (rms).
16. By comparing the received sound levels derived from the logarithmic noise
propagation model with the criteria proposed by Southall et al. (2007). Permanent
Threshold Shift (PTS) will occur in grey seals within 8m from the source of
impact piling and Temporary Threshold Shift (TTS) will occur within 14m. In
harbour porpoise, PTS will occur within 1-2m from the source of impact piling
and TTS will occur within 3-4m. Neither PTS nor TTS will occur in grey seal or
harbour porpoise even at the source of vibro-piling noise.
17. In terms of the dBht (Species) scale, the model predicts that grey seal will exhibit
a strong behavioural response at 90dBht within 1.3km from the source of
percussive piling and 40m if a vibratory hammer is used. Harbour porpoise is
predicted to show a strong behavioural response at 90dBhtht within over 5km
from the source during percussive piling and 1km from the source during vibro-
piling.
18. The effects of piling noise on marine mammals also needs to be considered in
relation to the duration of exposure. It is proposed that the piling work will take
approximately 10 days to complete, with vibratory piling thought to be the most
appropriate piling method based on the preliminary ground investigation results.
However, there may be times when harder material is encountered and in these
circumstances percussive methods may need to be adopted. Therefore any marine
mammals in Swansea Bay would only be exposed for a maximum of around 3
weeks (10 – 15 days, daytime only) and, taking a precautionary approach, it is
assumed that only a maximum 50% of that time would involve impact piling
19. It is also important to consider that the area in which the construction will take
place already experiences shipping, as well as maintenance dredging and,
therefore, marine mammals are likely to be habituated to a certain level of
anthropogenic background noise for periods of time.
20. Applying the standard impact assessment criteria, the sensitivity of harbour
porpoise and grey seal is considered to be moderate to underwater noise
generally. The probability of occurrence is high as is the importance of harbour
porpoise and grey seal, given their level of protection. Given that any effects
during vibro-piling, which is the preferred construction method, are limited to
EJR/EJR/343641/1/UKM/62783439.1 21
behavioural responses within 1km to the construction site, the magnitude of the
effects is considered to be medium. With respect to percussive piling which will
be used during construction on an ‘as required basis only’ (see above),
physiological effects (PTS or TTS) are predicted to occur within close proximity
to the construction site (14m) and a strong behavioural response will occur over a
larger area in the context of the 4155ha of subtidal habitat comprising Swansea
Bay (approximately 12% and 100% for grey seal and harbour porpoise
respectively) and therefore the magnitude of the effect is considered to be large.
The overall exposure and vulnerability of marine mammals to adverse noise
during impact piling is therefore considered to be high. Despite the temporary and
short term duration of the piling, given the level of exposure and sensitivity and
importance of marine mammals, the overall impact is assessed as a moderate
adverse impact during vibro-piling and a major adverse impact during impact
piling.
21. In order to reduce the significance of the impact during vibro and percussive
piling, several mitigation measures are proposed which are below. These include
following JNCC “Statutory nature conservation agency protocol for minimising
the risk of injury to marine mammals during piling” (JNCC, 2010) and also using
soft-start procedures for any vibro or percussive piling. With these measures in
place, residual impacts on marine mammals from construction noise are assessed
as being of minor adverse significance.
22. Confidence in this assessment is considered to be medium, given that the
underwater noise model is based on theoretical parameters and there is limited
empirical evidence of the behavioural effects of noise on marine mammals.
23. The following mitigation measures and monitoring will be implemented during
the installation of the dolphin piles:
i. Monitoring and mitigation would be undertaken during any vibro-piling or
impact piling following the guidelines highlighted in the JNCC “Statutory
nature conservation agency protocol for minimising the risk of injury to
marine mammals during piling” (JNCC, 2010);
ii. Installation of dolphin piles would be during daylight hours only;
iii. For vibro and percussive piling for dolphin piles, establishment of a
‘mitigation zone’ of radius 500m around the piling site, prior to any piling;
iv. Within this mitigation zone, detection would be undertaken by a Marine
Mammal Observer (MMO) and acoustically using appropriate Passive
Acoustic Monitoring (PAM) equipment;
v. Both the observers and equipment will be deployed at least 20 minutes
before any piling is due to commence;
vi. Any piling will not commence if marine mammals are detected within the
mitigation zone or until 20 minutes after the last visual or acoustic
detection;
EJR/EJR/343641/1/UKM/62783439.1 22
vii. The MMO/PAM operative should track any marine mammals detected and
ensure that they are satisfied that the animals have left the mitigation zone
before they advise the crew to commence percussive piling activities.
viii. Piling will commence using an agreed soft start procedure for at least 20
minutes (the gradual increase of piling power, incrementally, until full
operational power is achieved). The soft-start procedure will vary according
to hammer and pile design and other factors.
EJR/EJR/343641/1/UKM/62783439.1 23
3.9 to the Applicant
Please can the applicant provide an OS based plan (or set of plans), showing both
the locational context and the layout of the following construction areas (drawn at a
standard scale and with a north point):
(a) The concrete batching plant and associated yard and storage bin areas;
TLSB's Response
1. The information is provided on the plan attached at Appendix 3.9.1.
(b) The areas of sea wall and breakwater that are to be demolished;
TLSB's Response
2. Drawings 2.4.41, 2.4.42, 2.4.43 and 2.4.44 of the Planning Drawings submitted
with the Application (doc ref 2.4) show details of the demolition works. The
seawall is to be retained at the location of the pill boxes and 3m on either side (see
also paragraph 4.3.7.8 of Chapter 4 of the ES).
(c) Locations for storage of rock armour and other construction aggregate
supplies brought to site by sea; and
TLSB's Response
3. The information is provided on the plan attached at Appendix 3.9.1.
(d) The turbine fabrication yard area including the turbine fabrication building.
TLSB's Response
4. It is no-longer proposed to incorporate a turbine fabrication yard or turbine
fabrication building within the development to be authorised by the DCO.
Instead, the turbine manufacturing and assembly facility will be promoted by a
separate planning application under the Town and Country Planning Act 1990.
EJR/EJR/343641/1/UKM/62783439.1 24
3.10 to the Applicant. Part (a) of the question is aimed at all interested parties including (but not
restricted to Dŵr Cymru (Welsh Water) (DCWW) and NRW)
The sediment analysis chart in ES Chapter 4 (Project Description, Table 4.2) gives
the results of the analysis for a suite of metals taken from various samples within the
proposed lagoon area, at various depths. The analysis results are compared with
CEFAS thresholds, which consider their suitability for sea disposal. The
contaminants have not been considered against Dutch Standards, which are
environmental pollutant reference values used in environmental remediation,
investigation and clean up. The 0.7m depth sample from VC206 shows arsenic
values of 48.3mg/kg, which is close to the threshold for the Dutch intervention
threshold (55mg/kg)2. The copper, lead, nickel and zinc levels from this sample are
above the Dutch intervention levels. Samples from VC202, 204 and 208 also have
metal contents above the Dutch target value3 but below the intervention value. All of
the contaminated samples were located along the western and southern areas within
the lagoon footprint.
(a) Are the Dutch standards relevant to marine sediments? If not, are there any
other standards that are commonly used in the UK, which give thresholds
relating to metal contamination in sediments, in terms of their potential for
ecological harm in the marine environment?
TLSB's Response
1. The Dutch standards (and also Canadian Standards) were commonly used in the
UK before CEFAS developed its own standards which are now the accepted 'UK
Standards'. Effectively, the results derived for the Project can be compared against
any of the standards, but the CEFAS ones are the recognised UK standards and
hence the most appropriate standards to employ. As CEFAS will be advising
NRW (MLT) on the dredging aspect based on these standards, its standards have
been used in the assessment.
2. It is also worth noting that the standards are not 'pass' or 'fail' levels. They set
guidance levels against which each application can be assessed on a case-by-case
basis. In determining the standards, CEFAS have based the levels on a number of
factors – one of which is the potential ecological effect to the environment.
3. Therefore, Dutch standards remain relevant to marine sediments, but CEFAS
action levels are 'more' relevant since they are the accepted UK standards that
CEFAS will be looking to see used (since the development will be within UK
territorial waters). The CEFAS action levels are the recognised UK standards for
consideration of metal contamination in sediments, in terms of their potential
effect (including that on ecology) within the marine environment.
2 The soil remediation intervention values indicate when the functional properties of soils for humans, plants and animals
is seriously impaired or threatened. They are representative of the level of contamination above which a serious case of
soil contamination is deemed to exist.
3 The target value is related to Dutch national background concentrations.
EJR/EJR/343641/1/UKM/62783439.1 25
(b) What additional sampling and analysis of sediment samples within the
lagoon area is proposed, in order to identify whether there are any more
contaminated areas?
TLSB's Response
4. CEFAS has noted the higher levels of contaminants at VC206 and requested
additional sampling to check if the levels of contaminants were an anomaly or if
this location constituted a "hot spot". However it also confirmed that, as they are
below CEFAS Action Level 2, they are acceptable for disposal to sea.
5. In addition to this CEFAS has requested further sampling to characterise the
sediments within the proposed boating area (near to Work No. 6a and 6b) and to
meet the requirements of the potential maximum volume of material to be
disturbed/disposed. This is because when the initial sampling was undertaken a
smaller volume was estimated. However, based on the results of the preliminary
Geotech survey sediment results, which are provided Table 4.2, Chapter 4,
additional material will need to be disturbed/disposed, and hence further sample
analysis is required.
6. CEFAS has confirmed that based upon a 8.1 million m3 dredged volume
additional samples are required, further samples should be collected and analysed
for metals, organotins, Polyaromatic Hydrocarbons, Polychlorinated Biphenyls
(PCBs) and particle size analysis. Samples would be taken from four sites within
the secondary dredge area in the middle of the lagoon (see Appendix 3.10.1) and
from two sites within the dredging area for leisure access (the boating area as
discussed at paragraph 5 above). At every sampling site, samples will be taken at
every metre down to the proposed dredge depth.
7. As clarified with CEFAS, the secondary dredge area is unlikely to be dredged
and, as such, sampling in this area would not be required. However, should it
become apparent that the secondary dredge area needs to be dredged this area
would also need to be sampled and the analysis approved by the MLT prior to the
commencement of any undertaken of dredging within this area. As such, to
ensure that the construction programme is not restricted, sampling will be
undertaken in the secondary dredged area as well, such that the data is available if
need be.
8. Finally it is proposed to collect a vibro core sample from two additional locations:
the proposed outfall extension corridor (although not essential, as the material is
not to be disposed of, samples will be collected to provide information on ground
conditions); and the small triangle area adjacent to the Neath channel which will
be dredged to widen the entrance to the channel; identified under works to Neath
Harbour Channel including the widening of the entrance to the channel and
replacement of its training wall.4 The samples from both these sites will include
samples for the CEFAS chemical suite at 1m depth intervals.
4 Work 4 – Draft DCO
EJR/EJR/343641/1/UKM/62783439.1 26
(c) What measures will be taken to minimize the risk of mobilizing the metals
within these contaminated areas during dredging and avoiding their use in
the lagoon walls?
TLSB's Response
9. As identified by the results of the ground investigation, all samples are acceptable
for use and disposal where necessary and in fact 73.5% of samples were below
CEFAS action level 1. In terms of metal uptake, the fine grained fraction of
sediment, namely the silt to clay fraction, facilitates the uptake of metals more
than any other grain size. As such, these would tend to have the higher metal
levels. In terms of engineering properties for use in the Geotubes®, coarse
sediments and gravel are required for use in the Geotubes® and the smaller
fractions are not appropriate. Consequently, the objectives of engineering
structural stability and avoidance of contaminated areas are intrinsically linked.
10. Based on the results of the geophysical survey and the geotechnical surveys, the
most appropriate sediments in the lagoon footprint for use in the lagoon wall will
be targeted. As such, by nature of design, the sediments with the highest potential
for contamination (e.g. silts) will be avoided. In areas where material is
unsuitable either from an engineering or chemical point of view, as identified in
Chapter 4, 4.5.3.14 "Any of these areas would be entered into the onboard
computers of the dredger to ensure they are avoided."
11. These measures are expected to be secured by conditions to be attached to the
marine licence to be issued by NRW.
(d) Para 4.3.1.27 of ES Chapter 4 (Project Description) states that the 'final
location of the dredged areas will be dictated by the location of the most
suitable material from an engineering property and quality perspective'.
TLSB's Response
12. Yes. As discussed in response to Question 3.10 above there is a positive link
between the two characteristics and this will be to the benefit of the project
twofold: first, in terms of engineering properties; and secondly, in terms of
reduced potential contamination.
(e) Does 'quality' include consideration of contamination levels?
TLSB's Response
13. Yes. If an area has been identified as inappropriate (eg above action level 2), then
the area would be avoided. The results of the sediment analyses from the ground
investigation are all below Action Level 2 and therefore are fit for use, although
additional sampling is to be undertaken (see response to 3.9(b) above).
EJR/EJR/343641/1/UKM/62783439.1 27
3.11 to the Applicant
Figure 4.35 of ES Chapter 4 shows the location of the proposed access road and the
text in Paragraph 4.3.7.6 in this document states that the access track will be
constructed in the same method as the seawall, including rock-armour and then the
proposed dune-scape built up either side.
(a) Is it proposed to surface the access track, in order to reduce noise and dust
emissions from dump trucks and the lorries moving construction materials
including concrete around the site?
TLSB's Response
1. It is not proposed to surface this track during the construction phase. The track
will be used predominantly for access for earthworks plant engaged in the
construction of the eastern breakwater. The construction of the track will be
sufficiently robust to take this plant, as shown in Figure 4.36 of the ES. The
control of dust will be by water bowser, as and when required. The track will be
maintained regularly to retain a flat surface during construction, and this will
reduce vehicle noise. Noise will be monitored at the agreed receptors, and should
levels exceed the agreed allowable levels, control measures will be implemented
to rectify the situation.
(b) Is there any difference in construction methods/surfacing between the 'Port
Road' and the 'Project Road' identified in Para 4.3.7.9 and shown on Figure
4.37 and 4.38?
TLSB's Response
2. The construction of the two roads will be more-or-less the same. Where the roads
fall in plan over the existing internal port road (e.g. as shown in Figure 4.38 the
project road falls over the existing road) the construction of the existing road will
be assessed and retained if it meets design criteria. In this case the existing road
would be resurfaced.
(c) Please could the applicant show on a OS based plan the proposed access and
egress points into the construction areas for all HGV delivery lorries, as well
as details of lorry routing around the construction areas?
TLSB's Response
3. The Construction Masterplan (Ref. Plan No: 1117: WMP: 001, Appendix 3.9.1)
shows the access routes from the road network, and the internal site routes that
will be used for HGVs.
4. HGVs will generally leave Fabian Way at the Park and Ride junction (next to
McDonalds) and proceed to the site support area in which the materials are going
to be used. For example, the materials for concrete will go to the batcher (Area
B), where they will be mixed and loaded into ready mix trucks for onward
transmission to the temporary bund via the haul road shown over the broad
seaward park on the plan.
EJR/EJR/343641/1/UKM/62783439.1 28
5. Some materials, for example some of the steel reinforcement bars for the
concrete, will be delivered directly to the bunded site. In these instances, the
materials will drive to the site access control area (Area A on the Plan), where
they will be directed to the particular work-front inside the bunded construction
site.
EJR/EJR/343641/1/UKM/62783439.1 29
3.12 to the Applicant
ES Chapter 4 (Project Description) paragraph 4.5.2.5 describes the working hours
for the project.
(a) Will HGV movements to and from the construction site be restricted to
normal working hours (eg 0800-1800 Monday to Friday and 0800-1300
Saturday)?
TLSB's Response
1. It is not proposed to restrict movements to and from the Project to normal
working hours as this may affect the programme for delivery of the Project.
Nevertheless, it is desirable to limit movements of HGV’s at peak times, to
minimize disruption to the road network. Therefore, the approach is to balance
the needs of the project with the sensitivity (or otherwise) of receptors. It is
important to bear in mind that the vast bulk of material required for the Project
will be sourced from or delivered by sea.
2. As stated at paragraph 15.5.2.2 of the ES “Working hours during the construction
phase have not yet been finalised”. However, it is likely that there will be
continuous working during some phases of construction such as sea wall
construction or concrete pours for the turbine housing. As such, it is not proposed
to restrict HGV movements to normal working hours as this could considerably
constrain the overall Project programme. The onshore import of some materials
will be closely linked to the offshore works and those within the offshore
cofferdam. These works will be 24/7 and, as such, any restriction in deliveries
would affect the offshore programme. In addition to this, in terms of disturbance
to receptors, the proposed access would be off Fabian Way into/via an active Port,
which is not itself constrained by hours of operation.
3. Overall, Fabian Way is a busy dual carriageway with over 34,000 two-way traffic
movements per day during the week falling to around 19,500 on a Sunday (Table
15.3, Chapter 15 – ATC data near Baldwins Bridge). Although overnight these
levels are considerably lower, there are still on average over 3000 two way
movements between 2000hrs and 0600hrs during the week and on a Saturday, and
around 2600 two way movements on a Sunday. Table 15.5 in the ES provides
information on the proportion of HGV traffic and for Fabian Way this varies from
around 3% to 6% along the main dual carriageway. As such, potential
disturbance to receptors through additional 24/7 traffic during the temporary
construction phase as a whole is anticipated to be limited.
4. In terms of impact on other traffic using the local highway network, the key
busiest periods are the AM and PM commuter peaks, typically 08:00-09:00 and
17:00-18:00. When work is carried out in shifts, the start and finish times
generally do not coincide with the regular commuter peaks. For clarity, impacts
on vehicle movement, etc. are considered to be greatest during the day when more
traffic is on the road. As shown in Chapter 15 of the ES the assessment of traffic
has been undertaken during daytime hours, which is considered the worst case
assessment.
EJR/EJR/343641/1/UKM/62783439.1 30
5. It is considered that the effect on Fabian Way can best be managed by use of a
Construction Phase Travel Management Plan. This is annexed to the CEMP, and
must be approved by the relevant local planning authority under requirement 6.
(b) Will the concrete batching plant work 24/7?
TLSB's Response
6. The concrete batching plant will work 7 days a week during the construction of
the structures that form the generating station. It will work for 24 hours a day at
certain times where so needed. Such times are anticipated to be April 2016 to
September 2017.
EJR/EJR/343641/1/UKM/62783439.1 31
3.13 to the Applicant - Cornwall Council is requested to respond to part (c) in particular
Chapter 4, Para 4.6.2.1 and Table 4.6 identify that 1.92mt of rock armour and
0.87mt of rock underlayer will be supplied from Dean Quarry in Cornwall by 10,000
tonne capacity barge. As construction is anticipated to take place over 3 years, a rate
of rock supply/importation of circa 930,000 tonnes of rock is assumed necessary.
(a) Dean Quarry has recently been marketed for sale with the sales particulars
identifying that it operated up to 2005 with an annual output of
approximately 200,000 tpa. The loading jetty is included in the sale, although
the conveyor system installed on the jetty deck has been removed. In view of
the dormant nature of the quarry, and the previous output levels of circa
20% of the required output level to supply the TLSB project:-Is there a
supply agreement in place between the quarry owners and the applicant to
deliver circa 930,000 tpa of rock and rock armour over a 3 year period?
TLSB's Response
1. The production capability for Dean Quarry is described below. However, it is
important to identify a number of matters. First, the operation of Dean Quarry
previously undertaken was different in character and output to that proposed for
the Project. The grade of aggregate produced by the quarry was much finer and
necessitated different handling facilities to those now required to produce rock
armour. As such, it is not necessary to replicate removed machinery for the
Project.
2. Second, a supply agreement is not required. This is because the ownership of the
quarry is to be secured by a company associated with TLSB, meaning that supply
arrangements are not dependent solely on a contractual supply relationship – the
resource is available to the Project.
3. Rock armour production will be achieved through a specifically procured fleet of
robust earth moving equipment, and a suitable blasting schedule, with skilled
operators. Production estimates are generally provided in terms of normal quarry
operations. Therefore, generous efficiency factors are used to arrive at realistic
outputs. In normal quarry work the operating efficiency is a standard of 90
percent; with face loading equipment rated at 400 tonnes per hour (tph). In rock
armour work the operating efficiency is generally 60 percent of actual output.
4. The following calculation depicts how extraction of the required volume of rock
can be achieved, noting that the quarry will continue to operate outside the
shipping season (i.e. quarrying can continue even when seasonal restrictions
preclude the construction works in Swansea Bay from proceeding):
400 (tph) x 60% = 240 (tph) per machine x (2 machines) x (65 hrs/week) =
31,200 tonnes per week
31,200 tonnes/week x 48 weeks per year = 1,497,600 tonnes per annum
(tpa) capacity
EJR/EJR/343641/1/UKM/62783439.1 32
5. The annual capacity given above is approximately 20 percent in excess of the
total annual output required for the Project from the quarry (being some 1,200,000
tonnes).
(b) Will it be possible to re-establish the quarry infrastructure necessary in
order to deliver a major increase in rock outputs level within the required
timeframe?
6. Dean Quarry has the benefit of an existing planning permission, recently reviewed
under ROMP provisions allowing it to be worked until 2035. A copy of that
planning permission is attached at Appendix 3.13.1. In addition, the quarry
contains sufficient quantities of rock to supply construction of the Project. The
application to discharge conditions attached to the planning permission has been
submitted, which will enable the extraction of rock to commence by Q4 of 2014.
Subsequently, an appropriate marine licence application to ensure marine access
for Dean Quarry will be submitted in early Q4 of 2014.
7. Following the granting of planning permission the infrastructure will be updated
in accordance with the consent. As part of the proposed works, a new loading area
and breakwater will be constructed with the physical capacity to meet the loading
and shipping requirements of the proposed extraction programme, as detailed
above. Due to the size of rock required for the lagoon seawall, rock will be loaded
directly onto a rock barge by specialised plant. This supports TLSB’s confidence
that the required infrastructure can readily be put in place, with the means to
supply the volume of rock required, within the necessary timeframe.
8. Even if it were the case that Dean Quarry was not available at the very outset of
construction, which is considered unlikely, it would be possible to source rock
armour from other sources on an interim basis. Suitable alternative locations
from which armour could be sourced are:
a. “West of England” quarry in Cornwall
b. Quarry in Scotland
c. Quarry in Norway
(c) Are there any planning permission restrictions on outputs or schemes
required pursuant to conditions that have to be satisfied before rock
extraction can re-commence at Dean Quarry?
9. There are no restrictions on output from the quarry and an application has been
submitted to discharge the outstanding conditions to enable the rock extraction to
recommence. A copy of the planning permission is at Appendix 3.13.1.
(d) How realistic is it to expect deliveries of rock and rock armour from Dean
Quarry to take place at the rate of 3 x 10,000 tonne barges per week, all year
round?
10. The proposed works programme for Dean Quarry is to extract rock on a year
round basis, in accordance with the conditions of the minerals consent. Excess
rock, which is ready for delivery outside the construction seasons in Swansea Bay,
EJR/EJR/343641/1/UKM/62783439.1 33
will be stored in a designated rock storage and grading area, within the quarry
area.
11. The loading of rock from Dean Quarry and transport to Swansea Bay will only be
performed during a 30 week period per year (avoiding winter phases), ensuring
that the delivery of rock will be carried out in the optimal seafaring months. The
allocated sub-contractor will be required to have sufficient equipment and
expertise to load 30,000 tonnes per week and load vessels at a rate of at least 300
tonnes per hour. At this rate, a 10,000 tonne barge van be filled in 33 hours.
(e) What contingency arrangements would there be for rock supply at times
when the transport of the rock by sea cannot be achieved, due to unsuitable
sea conditions?
12. As stated previously, transhipment of rock will only be conducted in the best
seafaring conditions (being 30 weeks per year) per annum. TLSB will ensure
allocation of a leading marine contractor, familiar with working limitations of
their specialised fleet. There are two stockpile areas provided for in the
construction laydown areas of the Project, which allow for further contingency
should bad weather disrupt delivery. These are shown on the drawing at
Appendix 3.9.1.
13. On the basis of the above, TLSB does not consider that a contingency is required.
TLSB is confident that the delivery programme for the Project can be achieved.
EJR/EJR/343641/1/UKM/62783439.1 34
3.14 to the Applicant and Swansea Port Operator (ABP)
The possibility of bringing the raw materials for concrete by rail is identified in ES
Chapter 4, paragraph 4.6.3.2. The site of a potential rail-head for
cement/PFA/GGBFS/other is also identified on drawing 4.58 (this shows the
Indicative batching plant layout). The quantities of each type of building material
required and the number of HGV movements that these would generate are given in
Table 4.6.
(a) In view of the applicant's stated intention to include principles and elements
of sustainable development in the project design, if the raw materials for the
concrete were imported by rail, it would reduce the number of HGVs visiting
the site by an average of 400 HGV movements per week over the
construction phase. In order to establish whether these materials can be
delivered in a sustainable manner, by rail, it is important to establish
whether the adjacent rail head could be adapted for the importation of
construction materials:-Please could the applicant describe the technical and
financial feasibility (or otherwise) of using the adjacent port rail-head for the
importation of construction materials, including cement, cement replacement
materials and the construction aggregates necessary to produce 220,000 m3
of concrete over three years? The statement should address matters
including (i) the infrastructure improvements necessary to accommodate the
types and sizes of freight wagons required for the various types of
construction materials; (ii) the availability of rolling stock for delivering
materials by rail; (iii) the availability of time-slots on the rail network to
enable a reliable supply to construction aggregates, cement and cement
substitutes to be delivered to the project by rail. These details could be
addressed through a Statement of Common Ground.
TLSB's Response
1. TLSB's potential concrete suppliers have proposed differing sources of materials
for the concrete, with varying options for moving materials to the site, including
by rail.
Infrastructure Improvements
2. The railhead shown on Figure 4.58 accompanying the ES was an indicative
representation of the principle that, for delivery of cement and cement
replacement materials direct to the batching plant from rail, the batching plant
would have to be adjacent to rail provision. This is because cement and cement
replacement materials are pumped through flexible hoses from tankers (either
road or rail mounted) into the silos that are part of the batching plant. This is
theoretically possible for the northernmost of the two potential sites shown, using
existing rails. However, the existing rail connection into Swansea docks have
been out of use for some time, and would require extensive maintenance and
repair work to bring back into use. There are tight radii on these rails that would
mean that rolling stock would have to be moved by shunter rather than mainline
freight locomotives. Theoretically, this railhead could also be used for delivery of
aggregates used in the concrete.
EJR/EJR/343641/1/UKM/62783439.1 35
3. The existing rail infrastructure does not extend onto the potential construction
compound site shown on the peninsula between docks, nor the potential sites for
Permanent Works footprints, referred to in paragraph 4.7.7.3 of the ES. As such,
double handling would be required.
4. There is a working railhead to the north of Fabian Way which could be used to
offload materials for the concrete. This railhead has been offered by one of the
suppliers who has tendered to TLSB. This railhead would require the onward
transmition of materials using road wagons or dump trucks for aggregates and
road tankers for cementitious materials from the railhead to the batching plant and
adjacent storage areas.
5. There will be a premium to pay for delivery of materials by rail, based on the
quotation received from suppliers. The exact amount of this premium will depend
on cost of bringing the Port of Swansea railway lines back into use, and transfer
costs for materials from rail to the batcher.
The availability of rolling stock and capacity on the rail network
6. Rolling stock owned by prospective suppliers is available. Time slots are
currently available on the local rail network to allow delivery of these materials.
Arrangements for delivery of materials by rail have been discussed with the
landowner, ABP. The financial feasibility of delivery of concrete component
materials by rail can only be fully determined when the location for the batcher is
determined and the concrete supply for the project is chosen.
(b) In ES Chapter 4 (Project Description), Table 4.6, the last column is entitled,
'Movements per Week' and the number of HGV movements is given for the
various types of construction materials required by the project. In this table,
is a HGV movement equivalent to 1 HGV bringing materials to the site (in
which case there are also an equivalent number of empty HGVs leaving the
site), or do these HGV movements reflect the fact that for every delivery,
there is also an empty HGV leaving the site (in which case the number of
HGVs delivering material to the site are half of the stated numbers within
this table)?
TLSB's Response:
7. An HGV movement in the table represents 1 HGV bringing materials to the site,
with an equivalent number of empty HGVs leaving the site.
(c) Are the vehicle movements per week the average number of vehicles per
week over the project construction phase, or the maximum number of
vehicles per week? If they are average numbers, please could maximum and
minimum numbers of HGVs be provided, as well as the average and
maximum number of HGV movements on a daily basis during the various
stages of construction?
TLSB's Response:
8. The vehicle movements per week are quantities averaged over the period during
which the particular operation is programmed to happen. Where the delivery rate
EJR/EJR/343641/1/UKM/62783439.1 36
of an item is constant, this is maximum. For completeness, the maximum,
minimum and daily numbers are shown on the table attached to these Responses
at Appendix 3.14.1.
EJR/EJR/343641/1/UKM/62783439.1 37
3.15 to the Applicant
Two options are identified for dealing with the DCWW (DCC) water outfall pipe;
they are (i) leave it where it is and provide additional treatment processes to reduce
the risk of microbial contamination of the lagoon water or (ii) extend the outfall pipe
by 1.5km so that it discharges outside the southern edge of the lagoon.
DCC's view is that the only viable option in respect of the current outfall is extension
beyond the sea wall. This will provide a consistent solution which is resilient to
future potential population growth and the effects of climate change. DCC stated in
their RR that they, "therefore supports the extension of the outfall in accordance
with Work no. 3, Part 1, Schedule 1 of the draft DCO and is carrying out detailed
design and costings analysis to inform TLSB".
The Non –Technical Summary states in the introduction that, 'An integral part of
the Project is the provision of an enclosed water sports venue capable of providing a
safe body of water for local, regional, national and international events'. In view of
this aspiration and DCC's view:
(a) Would option (ii) provide a more robust solution for ensuring that the
microbial levels within the lagoon are kept at levels which facilitate water
sports activities all year round?
(b) If the outfall is left where it is, what is the risk and likelihood of unexpected
heavy rainfall events causing storm water flows to discharge into the lagoon
which give rise to elevated microbial levels and thus water sports would not
be safe?
(c) Please could the applicant identify on a plan the location, size (including
height) and layout of the proposed UV treatment plant, if it is to be
incorporated into the design?
(d) Is there an agreement in place between the applicant and DCWW for the
operation of the UV plant after it has been constructed?
(e) Is the applicant prepared to agree with DCC that the foul water outlet will
need to be extended outside the lagoon as part of the DCO?
TLSB's Response
1. Following submission of the Application, further discussions have been
undertaken with Dwr Cymru Welsh Water ("DCWW") to develop proposed water
quality enhancement options. Although detailed modelling has confirmed that,
UV disinfection, combined with a water quality management plan, would permit
large parts of the lagoon area to be used for all year round water sport activities,
in DCWW's view there was scope for longer term water quality management
issues and DCWW's duties.
2. The alternative option of extending the existing outfall by some 1.5km would
provide Excellent (rBWD) bathing water and improved shellfish water quality
throughout the lagoon, provided that the engineering consequences of taking the
outfall beyond the lagoon structure, ie the seawalls, are able to be resolved. These
EJR/EJR/343641/1/UKM/62783439.1 38
technical challenges have been progressed by the parties and an acceptable design
concept has been agreed in principle.
3. A number of other stakeholders, including Natural Resources Wales, the City and
County of Swansea and Port Health Authority, have noted the location of the
outfall within the lagoon. Each has indicated that an extension of the existing
outfall would be their preferred engineering solution in respect of long term use of
the lagoon for water contact sports or for the presence of shellfish beds.
4. On the basis of the above, based on DCWW's concerns about future
responsibility, on other representations raised, and having regard to the relative
neutrality of environmental impacts between the two options for water quality
enhancement, TLSB has proposed the exclusion of Work No. 8 (UV treatment
works) from further consideration as part of the authorised development
comprising the Project. As such, it is not necessary to address items a-d above
and item e is self-evidently considered in this response.
EJR/EJR/343641/1/UKM/62783439.1 39
Physical/Coastal Processes
3.16 to the Applicant
(a) Potential impact on water chemistry from impoundment resulting from sea
walls is described on page 51 of the Water Framework Directive (WFD)
Report. Is this impact considered acceptable under the terms of the WFD?
TLSB's Response
1. Yes. So far as TLSB understands, the impact on water chemistry from the
impoundment of the seawalls is acceptable in terms of the WFD objectives. The
conclusions drawn in the WFD report submitted with the Application (doc ref 8.3)
are currently being updated in line with discussions with NRW and an updated
report will be supported by the more detailed assessment of the individual
chemical components in Chapter 7 of the ES, at section 7.7.7.
2. The assessment referred to above demonstrates that the water impounded within
the seawalls constructed as part of the Project will not be subject to chemical
change simply as a result of impoundment. If, as is now proposed, the DCWW
long sea outfall is extended beyond the impounded area of the lagoon, the water
quality within the area of the lagoon itself will be improved above its quality as at
the present day.
3. Furthermore, the status of the waters in water bodies considered under Article 4.8
of the WFD is not predicted to deteriorate as a result of the Project in relation to
water chemistry see ES Chapter 7, 7.8.3.
(b) Given the need for there to be certainty over what is to be consented would
there be any negative consequences upon the removal of provisions from the
DCO to remove the option of retaining the outfall outlet pipe in its current
position (thus by default requiring the outfall to be relocated out with the
proposed lagoon)?
TLSB's Response
4. It is now proposed to remove Work No 8, comprising a UV treatment facility,
from the authorised development comprised in the draft DCO (doc ref 3.1). This
means that the approach to water quality within the lagoon can be addressed in
one of two ways. First, the use of the lagoon for water contact activities can be
regulated if the long sea outfall remains within the impounded area. TLSB is
confident that this would not unduly restrict the use of the lagoon, but does accept
that less weight could be afforded to the use of the lagoon for water-based leisure
activities in identifying the benefits of the Project. Secondly, the DCWW long
sea outfall could be extended beyond the seawall of the lagoon, with beneficial
consequences for water quality as described above.
5. A summary of the potential effects on water quality of impoundment is provided
below. Overall there would be an increase in disturbance during construction, but,
in the context of the wider extent of works associated with the Project as a whole,
and the long term benefit and security afforded by the outfall extension, these
could be perceived as minimal.
EJR/EJR/343641/1/UKM/62783439.1 40
6. As identified in the updated Table 4.1 the combination of Position A with the
outfall extension and variable speed turbines, with pumping at the end of the tidal
cycle, would still maintain excellent water quality in the lagoon.
1. Table 1 Summary of issues considered in option elimination process5
Outfall extension
Bathing water quality
in lagoon in operation
“Excellent” under the revised bathing water quality directive. No specific bathing
management plan required within lagoon. No adverse effect on other bathing
waters.
Shellfish water quality
in lagoon
WQ within the lagoon would meet excellent quality and therefore should meet
future shellfish standard.
WFD (Biological and
supporting elements)
No effect
WFD (Chemical) No effect
HRA No effect
Recreational and
commercial fishermen
The existing outfall provides localised habitat diversity (sand/gravel with rocky
outcrop) through the presence of the diffuser section and the increased nutrients
during significant wet weather. If the outfall is relocated to outside the lagoon this
will allow mobile species to colonise the new habitat and therefore remain as a
focal point for fishermen. The outfall extension will be 1.5km in a straight line
continuing the alignment of the existing outfall, which will take it approximately
750m outside the lagoon. This position will be approximately 3km from the start of
the Neath channel training walls and as such not in the direct line of shipping
access the area. The Neath Pilot boarding station will also be relocated further
south thereby moving waiting ships further away from the lagoon seawalls and
new outfall location (para 14.6.1.22). As such, it is anticipated that current whelk
fishing/potting activities as well as other recreational fishing activities should be
able to continue if the outfall were extended.
Construction
considerations
As discussed at paras 4.3.9.9 – 4.3.9.11 the new outfall section would be laid on the
seabed or buried at a similar depth (1-2m) as the existing outfall. The works would
be undertaken by marine plant which would already be on site for the construction
of the lagoon walls. In this way potential impacts are reduced and potential issues
relating to bio-security of invasive non native species (INNS) are not worsened.
The timing of construction of the outfall extension would be during the main
lagoon wall construction, and it would be completed before the final section of the
lagoon wall is put in place. To put the construction of the outfall in the wider
lagoon construction context, sediment disturbance from excavation of a narrow
trench will be minor compared to the worst case assessment undertaken within the
EIA for the lagoon wall. The impacts of the construction of the lagoon walls as a
whole have been assessed as minor adverse to neutral (locally) and neutral across
the wider Swansea Bay (Table 6.20). As the outfall construction works are
considered “minimal” in comparison to the wider lagoon wall construction, their
impacts are considered to be neutral.
In terms of water quality the extension of the outfall will involve the removal of the
diffuser section. During this period the initial dilution of the effluent will be
reduced and the outfall shortened by some 80-100m. Although this will not affect
compliance of the bathing waters during dry weather, if a significant storm event
were to occur during the construction phase and the outfall were to spill, bathing
water quality could be affected. As such the timing of these works would be
discussed and agreed with NRW with respect to bathing water compliance and the
potential need for “discounting” of routine beach sampling.
5 All paragraph and table references herein refer to the ES submitted with the Application.
EJR/EJR/343641/1/UKM/62783439.1 41
3.17 to the Applicant
Para 4.7.7.10 of Chapter 4 (Project Description) states that there may be a need to
bring a mobile crushing plant to site at times to re-process temporary slabs and
hard-standing as well as crushing of the concrete that is produced from the
demolition of the sea wall. It is important to understand whether the concrete
derived from the demolition of the sea walls and other concrete structures will be
crushed on site or whether these materials will be removed off site for recycling.
(a) How much concrete will be derived from the sea wall demolition, when will it
be produced within the construction phase and over what timescale?
TLSB's Response
1. TLSB estimates that there is 4000 cubic meters of concrete to be broken out of the
seawall. The initial demolition of parts of the seawall will take place at the start of
the construction phase, to allow access to the construction of the landfall and from
any adjacent areas to the breakwaters. It is currently anticipated that other sections
of the seawall will be demolished in the final year of construction, when the
public realm finishes are being constructed and when sea defence benefits of the
Project to the Swansea Port area have been realised.
(b) If it is not crushed on site, where will it go for recycling or disposal?
TLSB's Response
2. If there is concrete to be crushed, it this will take place on site. Concrete arising
from the works will be reused in the works. It will either be crushed and reused as
a fill or sub-base to roads, or it will be broken up and reused as fill.
(c) What is the likelihood of the concrete being crushed on site?
TLSB's Response
3. It is likely that some concrete will be crushed on site. This is likely to occur in the
site support areas.
(d) What mitigation will be used during the use of the crushing plant in terms of
noise and dust control and how will these measures be incorporated into the
DCO?
TLSB's Response
4. The use of water mist sprays at the point of dust release, or other appropriate best
practice methods will be used to suppress dust when dust is being released.
Adequate noise damping and shielding will be provided to ensure that noise levels
at receptors is within acceptable levels. A method statement which includes best
practice for dust suppression will be included in the CEMP, and use of a crusher
would be conditional on meeting these requirements.
EJR/EJR/343641/1/UKM/62783439.1 42
5. Allowable Noise levels at receptors will be included in the CEMP, and
monitoring of noise levels included establishing that these conditions are being
complied with.
6. The mobile crushing plant would be located in the Port near to the area of
proposed works, as such it will be in a dock/port environment. Notwithstanding
this, standard mitigation measures will be employed if needed (see Chapter 23,
19.1 of the ES), these would include:
Implementation of best practice for haulage contractors as per BS5228;
Screening of potentially noisy construction works (therefore acoustic
screening around the crushing plant);
Regulation of working hours;
regular maintenance of construction equipment; and
Soft start procedures for percussive piling.
7. In terms of dust, mitigation measures are summarised in chapter 23, 16.3. These
include:
No bonfires.
Site layout will be planned; machinery and dust- causing activities will be
located away from sensitive receptors, where possible.
Reduce speeds of vehicles tracking across un-made surfaces.
Use of water as a dust suppressant, where appropriate during dry weather.
Minimise drop heights for a delivery of aggregates · Regular vehicle
cleaning and covered loads.
Cleaning of mud tracked onto main highways if necessary.
8. As noted above, appropriate mitigation measures associated with noise and dust
would be secured in the CEMP through the DCO process.
EJR/EJR/343641/1/UKM/62783439.1 43
3.18 to the Applicant
Paragraph 4.7.7.15 of the Project Description states that rock will be stored in an
area of 400m by 400m at the western landfall and 250m by 250m at the eastern
landfall. It is unclear whether these areas will be located onshore or offshore. If they
are to be located offshore, how will the storage areas be constructed and where in
the ES has this operation been considered in terms of impacts on the environment?
TLSB's Response
1. Chapter 4 of the ES, paragraph 4.5.3.24, states that “The stockpiles would be
located near the landfalls at both sides of the Lagoon. The stockpile adjacent to
the western seawall would be approximately 400m by 400m and piled up to 3m
high. The stockpile adjacent to the eastern seawall within the lagoon would be
approximately 250m by 250m in area and piled up to 3m high”.
2. These stockpiles will be located in the intertidal area adjacent to the area of the
construction works at the western landfall and eastern landfall, within the Order
limits. See drawing at Appendix 3.9.1 where these areas are shown on an OS
based map.
3. The loss of this habitat is included in Table 4.4a, Chapter 4, which shows that the
loss of intertidal area as a result of these rock stockpiles between year 1 and 3 of
construction will be approximately 22.25 ha. The positioning of the western rock
storage area has been chosen to fall within the area used for the western landfall
facilities/boating centre. In this way the area affected is potentially reduced and
impacts are minimised. The long-term direct loss of these intertidal habitats as a
result of the Lagoon itself has been assessed specifically in Sections 8.5.8 and
8.5.9 of the ES. In terms of the eastern rock area, once operational this intertidal
area will re-colonise.
4. The rock stockpile areas are temporary facilities needed during construction only.
Once construction of the seawalls is completed, these stockpile areas are no
longer needed and will be removed. They will then be allowed to revert to their
original status. Monitoring of this process can be undertaken, and, if required,
would take the form of low level surveys.
5. The construction methodology for the stockpile areas is not specialised. It
involves first, Sabellaria translocation works and possibly removal of some of the
stones/cobbles to be used as herring spawning media. Thereafter, establishment
simply requires placing the stockpiled rock at this location. There will be
different stockpiles for each of the different rock size fractions, and rock will be
placed up to 3m high. There will be sufficient space in between the various rock
stockpiles to allow easy access by trucks and loading equipment. The stockpiled
rock will then later be used for the construction of the seawalls. No specific
preparation of the stockpile area will be required.
EJR/EJR/343641/1/UKM/62783439.1 44
3.19 to the Applicant
In view of the proposed location of the Project walls adjacent to the channels of the
River Tawe and River Neath:
(a) Will the presence of the lagoon walls adjacent to the river channels give rise
to a reduction in velocity of the river water entering the bay?
TLSB's Response
1. The situation post-construction remains similar to that of the baseline for the
River Neath Estuary (with training walls aligning the river flow), and there
will be no blockage to river flow from the Tawe (the existing breakwater
arrangement at the mouth of the Tawe is also maintained). Consequently,
there is not predicted to be any reduction in velocity of river waters entering
the Bay.
(b) Will there be an increase in sediment deposition either side of the lagoon,
caused by changes in river velocity and/or turbidity?
TLSB's Response
2. The coastal processes assessment contained in Chapter 6, summarised at Table
6.22 as it relates to Monkstone, predicts increases in sediment deposition, but not
as a result of changes in river velocity or turbidity. For the River Tawe, the
increases are likely to be as a result of reductions to flow and waves resulting in a
lower energy environment, meaning deposition is more favourable than in the
baseline case. For the River Neath, the potential for deposition is primarily
associated with the short-lived deposition during the construction phase.
EJR/EJR/343641/1/UKM/62783439.1 45
Statement to frame following questions
Chapter 6 of the ES is entitled Coastal Processes, Sediment Transport and
Contamination. In paragraph 6.5.1.41, baseline conditions for flood and ebb tidal
currents are described as follows:
The characteristics of the baseline flood and ebb tidal currents within Swansea Bay
lead to a clear tidal residual pattern (see Figure 6.40, Volume 2), which includes:
i. an anticlockwise circulation eddy to the west of Swansea Channel, extending
from the shoreline to the 10m below CD contour;
ii. shoreline parallel residuals across the Swansea Bay intertidal areas in a
westerly direction between Mumbles Head and Port Talbot; and
iii. north-east tidal residuals in the eastern region of the bay, between 0m CD
and the 10m below CD contour, orientated towards Aberafan Sands and
Port Talbot.
The long term effect of creation of a lagoon is described in paragraph 6.5.2.59 of
Chapter 6 of the ES Coastal Processes in the following terms:
It is considered that the completed Project will modify and redefine the
existing residual circulation within the western region of Swansea Bay by
effectively splitting the bay into two smaller embayment cells whereby the
Lagoon structure essentially becomes a headland, thus restricting exchanges
between either sides of the Lagoon; and
… the western region of the bay is expected to experience an increased
'trapping' potential of sediments (predominantly mud) in the future
compared to existing conditions, particularly across the shallow subtidal
areas adjacent to the Blackpill SSSI and within the Swansea Approach
Channel.
EJR/EJR/343641/1/UKM/62783439.1 46
3.20 to NRW and Applicant
Are the dominant forces affecting sediment transportation and coastal morphology
in and around Swansea Bay sufficiently understood to enable reliable assessments to
be made of the broad consequences for patterns of erosion and deposition in and
around the Bay from the introduction of a coastal lagoon between the mouths of the
Rivers Tawe and Neath?
TLSB's Response
1. The assessment of potential effects of the Project on coastal processes, sediment
transport and contamination (as reported in Chapter 6 of the ES), has followed an
appropriate baseline understanding and technical approach as used for a wide
number of other EIA studies on other Nationally Significant Infrastructure
Projects (including port developments (such as the ABLE Marine Energy Park
EIA and a number of Round 3 offshore wind farm projects). The approach taken
involves an initial data collation stage, whereby previous studies of relevance and
existing and newly-collected survey data have been assessed to provide a suitably
comprehensive description of the baseline environment (termed ‘evidence base’).
From this baseline description (provided in Section 6.4 of the ES), a conceptual
understanding of the dominant controls on coastal processes across the study area
has been derived. The EIA studies have been carried out using the ‘Source >
Pathway > Receptor’ model, to assess how a predicted effect on any one part of
the system potentially results in a direct (or indirect) effect on the identified
receptor.
2. Within the baseline description and conceptual understanding, consideration has
also been given to the various sources and sinks of sediment across the study area.
These sources and sinks differ in regard to the different material types, with
coarser material (sands and gravels) being controlled by different pathways to
those controlling finer (mud) material. These sediment transport processes
ultimately control the coastal morphology across the study area. With specific
regard to coastal processes, the assessed controls on the sediment regime and
morphology are primarily the hydrodynamic and wave environments, which act to
control the various aspects of sediment transport across both Swansea Bay and the
wider area.
3. The relative importance of the controls on sediment transport varies depending on
the type of sediment under consideration (mud, sand, gravel) and on the transport
pathway. Generally, sand material is transported under predominantly tidal
conditions in the outer part of the bay and along the Bristol Channel, with large
swell and storm waves (in particular) playing a more dominant role in the
shallower parts of the Bay where littoral transport processes may occur. With
regard to mud material, the transport pathway is almost entirely tidal, with waves
only acting to stir up the bed in shallower regions (or in deeper water under larger
storm conditions) and entrain more material into suspension, for onward transport
by the tide. Section 6.4.3 of the ES provides a detailed description of the
conceptual understanding of the sediment regime (sources, pathways, sinks), and
morphology across the study area.
EJR/EJR/343641/1/UKM/62783439.1 47
4. An enhanced description of the baseline environment (including associated
process controls) has been prepared for Kenfig SAC (Appendix 1.15.1), and
Crymlyn Burrows SSSI and Blackpill SSSI (Appendix 1.15.1) in response to
ongoing discussions between TLSB and NRW in respect of the negotiation of
appropriate Statements of Common Ground.
5. Assessment of the identified controls has been informed through the description
of the baseline environment and conceptual understanding of it. In addition,
numerical modelling software has also been used to support and enhance the
baseline description and conceptual understanding of the coastal processes, and to
subsequently inform the assessment of potential effects from the Project. The
baseline hydrodynamic and wave models have been calibrated and validated
against a range of field observations, to ensure they are providing an adequate
description of representative ‘real-world’ conditions (as described in Appendix
6.1, Volume 3). Furthermore, the results of sediment transport modelling for
muds have been verified against known annual dredging (and, hence, inferred
deposition) rates within the Port Talbot and Swansea approach channels. The
modelling software applied within the Project is commonly used to assess the
potential EIA effects of proposed developments. The software is considered state
of the art and fit for purpose in describing the relevant physical processes across
the study area.
6. The calibration and validation stage of the modelling approach provides a
measure of the ability of the model to adequately replicate the baseline conditions
observed across the study area. The performance of the model has been tested
against a defined set of calibration guidelines, and has been shown to perform
well within the defined limits (see Appendix 6.1 to the ES - doc ref 6.3). The
successful calibration and validation of the baseline models helps to limit the
uncertainty within the assessment and provides confidence that the tools being
used to inform the EIA are wholly suitable and fit for purpose.
7. As a result of the approach taken (combined with the existing understanding and
the breadth of available studies within the wider Swansea Bay/Bristol Channel
region), it is considered that the dominant forces affecting sediment transportation
and coastal morphology in and around Swansea Bay are sufficiently understood.
This has enabled assessments to be made of the likely broad consequences of the
Project for patterns of erosion and deposition in and around the Bay, the results of
which are considered reliable, sensible and justified. These assessments, and the
conclusions drawn from them are recorded in Chapter 6 of the ES.
EJR/EJR/343641/1/UKM/62783439.1 48
3.21 to the Applicant
Have the consequences of changes in the processes and patterns of erosion and
deposition on the shoreline east and west of the proposed lagoon been appropriately
examined and assessed for:
1 Features of interest of:
(a) the Kenfig SAC
(b) the Crymlyn Burrows SSSI; and
(c) the Blackpill SSI.
2 The sandy beaches and amenity value of:
(a) Swansea Town Beach; and
(b) Aberavon Town Beach (Aberafan Beach).
TLSB's Response
1. Prior to the EIA studies undertaken for the Project, an initial feasibility study6 was
carried out to assess and confirm the extent of the study area and the likely broad-
scale effects of a lagoon scheme (provided at Appendix 3.21.1). The scoping
phase of the EIA studies identified (through consultation with stakeholders) the
coastal processes receptors that required consideration with the detailed
assessment. Following this, the detailed EIA studies looked to provide predicted
effects for each of the identified receptors (a list which included each of the
features included in 1 & 2, above, along with a number of other receptors, as
presented in Table 6.22, in Chapter 6 of the ES).
2. As described above, the approach taken within the assessment has been to
describe the baseline conditions and develop a well-established conceptual
understanding of the processes across the study area. The assessment of potential
effects for each receptor (including each of those listed above) has subsequently
been informed by this conceptual understanding in order to provide context to any
predicted change.
3. The assessment of potential effects for each receptor has been carried out for each
project stage (construction, operation and decommissioning), and for a range of
representative conditions (calm, typical, storm conditions, sea-level rise as a result
of projected climate change etc.). Furthermore, the detailed assessment has
considered the short, medium and long-term effects on each receptor, using a
realistic worst case scenario approach (see Section 6.5 of the ES for the
assessment of effects for each project phase, along with descriptions of the
realistic worst case scenarios, where appropriate).
6 R.1956TN, May 2012, Swansea Bay Tidal Lagoon Feasibility Modelling
EJR/EJR/343641/1/UKM/62783439.1 49
4. As discussed above, the assessment used the ‘Source > Pathway > Receptor’
approach, quantifying any changes by comparing the baseline scenario (existing
situation) to the scheme scenario (with inclusion of relevant Project components).
When considered against the conceptual understanding of process controls across
the study area, this approach enables the identification of both direct and indirect
effects on the listed receptors. In this way, in addition to any direct effects that
might be predicted, an effect on a specific pathway that is linked to a receptor (for
example, the sediment transport pathways feeding sediment to Kenfig SAC) is
also considered with due regard to any potential knock-on effect.
5. Furthermore, the coastal processes assessment has also considered potential
cumulative and in-combination effects arising from the Project and others that are
located across the wider study area. The scoping phase also identified the full list
of activities (as agreed with stakeholders) that was subsequently included in the
cumulative / in-combination assessment, and Section 6.6 of the ES details the
results of this phase of the EIA studies.
6. A paper specifically addressing effects upon Kenfig SAC, Crymlyn Burrows SSSI
(which is largely related to nitrogen deposition, rather than sediment transport)
and Blackpill SSSI is attached at Appendix 1.15.1.
7. As such, it is considered that the consequences of changes in the processes and
patterns of erosion and deposition on the shoreline east and west of the proposed
lagoon have been appropriately examined and assessed for the receptors listed in
Written Question 3.21. A summary of the receptors and the impacts is provided
in Table 6.22 (Chapter 6); specifically, Swansea Town Beach is termed “Swansea
designated bathing beach” and additional assessment is also provided for “Wider
bay Swansea sandy beach areas and effect on lower shore”. Please note also that
Aberavon Town Beach (Aberafan Beach) is referred to as Aberafan Sands in
Table 6.22.
EJR/EJR/343641/1/UKM/62783439.1 50
3.22 to the Applicant
Are there other features of Swansea Bay that are considered particularly sensitive to
changes in patterns of erosion and deposition that have not been appropriately
examined and assessed
TLSB's Response
1. As discussed in the Response to Written Question 3.21, the scoping phase of the
EIA studies identified the coastal processes receptors that required consideration
within the detailed assessment. The scoping phase for the coastal processes
assessment identified a number of receptors across the study area. These included
the features of interest listed at Written Question 3.21 (e.g. Kenfig SAC, both
Crymlyn and Blackpill SSSIs; amenity beaches), along with other receptors (such
as the Swansea, Neath and Port Talbot approach channels). Aspects of the EIA
that were identified as having a coastal processes component, along with the
identified receptors, are provided in Section 6.5.0.5 and Table 6.22 of the ES.
2. Similar scoping phases were carried out for each EIA topic and any reliance or
dependence between different EIA topics has been included within the ES. As
such, the assessments of potential effects on other topic receptors, which might be
directly or indirectly influenced by coastal processes (e.g. benthic ecology, marine
mammals, birds, fish, navigation, recreation etc.), include consideration of such
within the relevant ES chapter. A description of the interrelationships between
EIA topics is provided in Chapter 24 of the ES.
3. As a result of the approach to the EIA studies (including the scoping phase and
the inclusion of interrelationships between topics and associated
interdependencies between topic receptors), it is considered that there are no other
features of Swansea Bay that are particularly sensitive to changes in patterns of
erosion and deposition, that have not been appropriately examined and assessed
and reported in the ES.
EJR/EJR/343641/1/UKM/62783439.1 51
3.23 to the Applicant
Would further hydrological modelling significantly assist in predicting the impact on
coastal processes of the existence of the proposed lagoon?
TLSB's Response
1. The numerical modelling carried out as part of the detailed EIA studies into
potential effects on coastal processes has followed widely accepted methods used
for this type of assessment. A number of representative scenarios have been
assessed across and within each process control. These scenarios provide an
assessment that includes consideration of a number of:
i. Tidal conditions – spring tide / neap tide / surge tide / sea-level rise as a
result of projected climate change;
ii. Wave conditions – various return period events from each of two dominant
wave approach directions;
iii. Sediment grain sizes – ranging from sand to mud, with relative proportions
of each informed by targeted project surveys; and
iv. River flow scenarios – typical and high discharge rates (associated with
high precipitation conditions).
2. Where considered relevant and representative, these assessment scenarios have
not only been considered in isolation but also in combination. For example, the
assessment of potential changes to wave conditions has been assessed for each of
‘spring tide’, ‘spring tide + surge tide’ and ‘spring tide + sea-level rise’ tidal
scenarios; whilst the assessment of potential changes to sediment transport
pathways has been assessed for each of ‘tide only’, ‘tide + typical wave’ and ‘tide
+ extreme wave’ scenarios.
3. The approaches taken, and the respective scenarios assessed, are considered
appropriate and representative to inform the likely effects on coastal processes for
the purposes of EIA. As such, whilst further modelling could be undertaken, it is
considered that this would be of limited value. Such additional modelling would
be likely only to reinforce the findings of the present assessment, rather than
producing materially different outcomes. The conservative nature of the
assessment (primarily achieved through the use of the realistic worst case scenario
approach) acts to manage, wherever possible, the uncertainties that exist within
both the Project description and the approach to assessment. The approach taken
by TLSB in respect of "uncertainty" in the assessment approach for coastal
processes is provided at Section 6.3.5 of the ES, whilst Chapter 4 of the ES
provides a description of the Project options which have been included within the
EIA.
4. It should noted here that the Adaptive Environmental Monitoring Plan (which is
in development through consultation with NRW will look to ensure predicted
changes are confirmed (or otherwise) and quantified (where appropriate), likely
over the lifetime of the Project. Additional modelling at this stage is unlikely to
change these monitoring requirements, which are likely to be extensive (both
spatially and temporally) – at least over the short-term – as a result of this Project
being a ‘first-of-its-kind’ development.
EJR/EJR/343641/1/UKM/62783439.1 52
5. Consequently, it is considered that further hydrological modelling would not
significantly assist in further predicting the impact on coastal processes of the
existence of the proposed lagoon.