1

Technical Note #01 To : Stuart Hannell From : Nick Cooper Date : 7 March 2017 Copy : John Freer Our reference : PB4151/TN01/303294/Newc Subject : Lochaline Ferry Terminal - Coastal Processes Assessment

Background Caledonian Maritime Assets Ltd. (CMAL) is proposing works to replace an existing ferry aligning structure at Lochaline Ferry Terminal with a new solid pier structure. Marine Scotland has advised that “the proposed size and use of the solid pier structure will generally be in keeping with the current size and use of the existing infrastructure. The drawings provided indicate that the proposed solid pier will be constructed in the same location as the existing alignment structure therefore there will not be a significant increase in footprint size. It is however appreciated that the existing structure is ‘open’ and the proposed structure will be ‘closed’ therefore coastal processes may be impacted. An assessment of potential coastal process impacts should therefore be submitted in support of any marine licence application”. This Technical Note #01 provides the necessary assessment of the potential impacts on coastal processes caused by the construction and operation of the new facility. Given the likely scale and significance of the changes expected, numerical modelling of the effects is deemed disproportionate and instead a desk-based investigation, using the professional judgement of an experienced geomorphologist has been used in the assessment. Lochaline

Lochaline is a village in the Morvern area of the Scottish Highlands. It is situated at the western side of the mouth of Loch Aline. The sea loch connects hydrodynamically to the Sound of Mull and a ferry operates between Lochaline and Fishnish on the Isle of Mull. An oblique aerial view of the mouth of Loch Aline is shown in Figure 1.

7 March 2017 PB4151/TN01/303294/Newc

https://en.wikipedia.org/wiki/Morvernhttps://en.wikipedia.org/wiki/Highland_(council_area)https://en.wikipedia.org/wiki/Loch_Alinehttps://en.wikipedia.org/wiki/Fishnishhttps://en.wikipedia.org/wiki/Isle_of_Mull

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Figure 1 – Mouth of Loch Aline

(Lochaline–Fishnish ferry seen in transit)

Lochaline Ferry Terminal – Existing Structure

The existing ferry terminal facilities at Lochaline are shown in Royal HaskoningDHV drawing no. PB4151-1000 (Appendix A). The structures are aligned approximately 50°N and comprise the following elements (Figures 2 – 6):

• A sloping concrete slipway to provide RO-RO access for vehicles to the ferry, extending from the vehicle marshalling area (located above MHWS) to below MLWS over a distance of approximately 50m;

• Rock armour protection to the southern side of the slipway along its length;

• A timber-piled support structure to a metal pier walkway which provides crew access to

the ferry to the immediate northern edge of the slipway;

• An inner dolphin constructed as a rock filled sheet pile cell with a reinforced concrete deck slab;

• A suspended metal walkway aligned nor-northeast from the inner dolphin to reach the outer berthing dolphin, a reinforced concrete structure supported on steel H piles – added after construction of the original berthing facilities; and

• A low bund of gabions (southern side) and rock fill (northern side) covered by a Fabriform mattress on the immediate northern side of the piled pier.

It should be noted that the Fabriform mattress-covered bund has a crest height of above mid-tide level along its length (highest at the inland section where it reaches around only 0.6m below

7 March 2017 PB4151/TN01/303294/Newc

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MHWS). Also, the deck level of the inner dolphin structure at the end of the aligning structure is around mid-tide level.

Figure 2 – Ferry berthed and being loaded from the slipway

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Figure 3 – Sloping slipway and rock armour protection (timber aligning structure to rear)

Figure 4 – Fabriform mattress-covered low berm (left), aligning structure (centre) and sloping concrete slipway (right)

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Figure 5 – Fabriform mattress-covered low berm

Figure 6 – Suspended walkway extension to dolphins

Lochaline Ferry Terminal – Proposed Structure

The proposed works to the ferry terminal at Lochaline are shown in Royal HaskoningDHV drawing no. PB4151-1100 (Appendix B). The existing concrete slipway, rock armour protection and dolphins are unaffected but the following changes are proposed:

• The Fabriform mattress-covered low berm and the open timber-piled access walkway are to be replaced with a solid, steel sheet piled wall which will provide the necessary crew access to the ferry to the immediate northern edge of the slipway.

The proposed size and use of the new solid pier structure will generally be in keeping with the current size and use of the existing infrastructure. The proposed solid pier will be constructed in the same location as the existing alignment structure and therefore there will be no significant increase in footprint size. The principal difference between the existing and proposed pier structures is that the existing timber-piled alignment structure is ‘open’ whilst the proposed replacement pier structure will be ‘closed’.

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Coastal Processes Assessment Given the above difference between the existing and proposed pier structures, Marine Scotland considers that coastal processes may be impacted and an assessment of potential coastal process impacts should therefore be submitted in support of any marine licence application. This coastal processes assessment has been informed by means of:

1. analysis of charts and data to inform understanding of the bed morphology and any changes over time in the vicinity of the existing ferry terminal structures;

2. expert-based assessment of the governing hydrodynamic processes which prevail; and

3. desk-based geomorphological assessment of how the principal difference between the existing and proposed pier structures may affect coastal processes and bed morphology in the future.

The following data and information has been used to inform the assessment:

• Admiralty Chart 2390-0: Sound of Mull (UK Hydrographic Office)

• Admiralty Chart 2390-2 – Sound of Mull / Loch Aline (UK Hydrographic Office)

• Bathymetric and topographic survey 13th June 2012 (Aspect Land & Hydrographic Surveys Ltd.)

• Multibeam bathymetric survey 18th January 2017 (Aspect Land & Hydrographic Surveys Ltd.)

• Level difference drawing between surveys undertaken 17/06/13 & 18/01/17 (Aspect Land & Hydrographic Surveys Ltd.)

From the Admiralty Chart 2390-0, it can be seen that the Sound of Mull is a deep channel running between Morvern and the Isle of Mull. At its greatest depth along the ferry transit route between Lochaline and Fishnish, depths in excess of 130m below Chart Datum (CD) are reached (Figure 7).

Admiralty Chart 2390-2 shows that Loch Aline can be characterised by four distinct morphological zones (Figures 7 and 8).

1. First, a narrow entrance extends into the sea loch from the Sound of Mull. The Lochaline ferry terminal is located within this entrance and the depths reach in excess of 3m below CD (Figure 8).

2. The entrance then connects to the deepest part of the loch, which reaches depths in excess of 40m below CD (Figure 8).

3. To the immediate north of the deepest section is a shallower section (refer back to Figure 7), although depths still reach up to 10m below CD.

4. The final section is an area of shallow intertidal into which the Rannoch River discharges (Figure 7).

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Figure 7 – Bathymetry of the Sound of Mull in the vicinity of Lochaline

Admiralty Chart 2390-0: Sound of Mull

Figure 8 – Bathymetry of Loch Aline in the vicinity of Lochaline

Admiralty Chart 2390-2 – Sound of Mull / Loch Aline

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The bathymetric surveys undertaken by Aspect Land & Hydrographic Surveys Ltd. show that to the immediate north of the ferry terminal there is a shallow bay in the shore, which has an inter-tidal width of up to 50m at its widest point (Figure 9). There appears to be a shallow accumulation of sediment to the immediate north of the Fabriform-covered berm which extends as a small ‘limb’ towards the terminal end of the structure.

Figure 9 – Inter-tidal Bay to north of Ferry Terminal

South of the terminal is a very small indented bay which provides a very small accumulation of sand and shingle and further south still the inter-tidal width is narrow, around only 15m.

From the ferry terminal, bed depths progressively increase to around 3.0 – 3.8m below CD over a distance of around 50m, and a channel of this depth forms a navigable route for vessels exiting and entering the sea loch to and from the Sound of Mull.

The isopachyte chart showing the difference in bed levels between the 2017 and 2013 surveys (Appendix C) shows that in the vast majority of the surveyed area, the bed level changes are within ±0.2m. This indicates that there generally is no significant bed level change over a time period of 3½ years. This is likely to be attributable to the following factors:

• There is little available sediment to be eroded, transported and deposited within Loch Aline or the Sound of Mull due to the predominantly hard rock nature of the solid geology; and

• The relatively high tidal current velocities through the mouth of Loch Aline sweep the bed generally clear of superficial sediment deposits.

Note the ‘limb’ of accreted sediment immediately

north of Fabriform mattress-covered bund

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It is notable that some (very minor) bed erosion occurred in the vicinity of the ferry terminal and this may potentially be associated with propeller thrust during manoeuvring operations. The principal concern raised by Marine Scotland was that the existing timber-piled alignment structure is ‘open’ whilst the proposed replacement pier structure will be ‘closed’ and may therefore have an effect on coastal processes. However, it should be remembered that whilst the timber-piled structure is ‘open’, the low bund to its immediate north is a solid structure, currently with a crest height of above mid-tide level along its length. Indeed, along its most inland section the bund crest is around only 0.6m below MHWS. Also, the solid steel sheet piles encasing the concrete structure at the end of the pier are at around mid-tide level. Therefore, these structures combined already present something of a ‘blockage’ to coastal processes in the present day situation under much of the normal tidal cycle, with only the few hours either side of high tide being unimpeded in the uppermost section of the water column. Indeed, it is due to this present-day impediment through much of the tidal cycle that sand and shingle has, to a limited extent, accumulated immediately north of the bund. If there was more sediment within the loch available for mobilisation and transportation, it is likely that a greater extent of accumulation would have been observed already due to this. Therefore the effect of the new ‘solid’ pier structure on the existing sediment transport processes will not be dissimilar to the present day for much of the tidal cycle. The sand and shingle which, in places, is present on the inter-tidal zone to the north of the ferry terminal would in any case be transported by bedload transport and not as suspended load in the water column, so the difference caused by the new structure ‘blocking off’ the upper sections of the water column at the peak of the tide will have no effect on sediment transport. There will, however, be an acknowledged effect on flow pathways a few hours either side of high tide. During the flood tide through the mouth of the sea loch, the tidal flow will simply be diverted along the axis of the structure towards the nor-northeast. During the ebb tide, the flow from the inter-tidal bay to the immediate north of the terminal will be constrained by the new ‘solid’ structure. However, this process will be so minor and confined to such a short part of the tidal cycle, that the broader hydrodynamic regime will be unaffected. If there was plentiful sediment available within the loch system, the newly imposed constraint for part of the tidal cycle might have led to increased sediment deposition within this inter-tidal area, but there appears to be relatively little sediment available and therefore such changes are not likely to be significant. There will be no wider knock-on effects since the changes are so localised, both spatially (close to the ‘solid’ structure) and temporarily (restricted to the upper part of the tidal cycles, a few hours either side of high tide). Changes at high tide itself are likely to be minor because that is when slack water occurs and there is very little tidal flow.

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Conclusion The proposed new ‘solid’ pier at Lochaline Ferry Terminal will cause some additional adverse effects to the existing coastal processes compared to the present arrangement, especially in terms of diversion of the flood flows into the sea loch from the Sound of Mull and impediment to the ebb flows from the sea loch to the Sound of Mull, but these additional effects over the present-day situation will be:

1. localised to the vicinity of the ferry terminal;

2. minor in magnitude; and

3. confined to the few hours either side of high water during the tidal cycle (the present bund causes effects 1 and 2 above in the present day to notably above mid-tide level).

As there appears to be relatively little sediment available for mobilisation, transport and deposition within the loch, such changes to the hydrodynamic flows are not likely to be significant on sediment transport processes. If any changes were to be expected, they would most likely be in the form of additional deposition in the small ‘limb’ of accumulated sediment which already runs along the immediate northern face of the existing bund.

Due to the nature of the envisaged changes to the hydrodynamic flows, there are not envisaged to be any far-reaching adverse effects elsewhere in the sea loch and surrounding waters.

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Appendix A – Existing Layout

7 March 2017 PB4151/TN01/303294/Newc

A1 A2 A3 A4 A5 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21

D1 D2 D3 D4 D5 D6 R1 R2

A

A

B

B

M.H.W.S +2.4 OD

0.00 OD

APPROXM.L.W.S

NAVIGATIONLIGHT

ROCK FILL

ROCK FILL

ROCK ARMOURSLOPE

FABRIFORMMATTRESS

GABIONS

M.H.W.S +2.4 OD

0.00 OD

APPROX M.L.W.S

SC

LP

LP

LP

LP

RS

RS

RS

RS P

P P

Dr

Cul

v

TL

TL

TL

TL

LB

2

A1

A2

A3

A4

A5

F6

F7

F8

F9

F10

F11

F12

F13

F14

F15

F17

F18

F19

F20

F21

D1

D2

D3

D4

D5

D6R1

F16

F1

F2

F3

F4

F5

R2

MHW

S +2

4.00

MLW

S +

A

AB

B

ROCK FILL

ROCK ARMOURSLOPE

FABRIFORMMATTRESS

GABIONS

BED LEVEL

M.H.W.S +2.4 OD

0.00 OD

APPROX M.L.W.S

SC

SC

SC

LP

LP

LP

LP

RS

RS

RS

RS

RS

P

P

P

Dr

Culv

Culv

Culv

Culv

MP

KO

KO

TL

TL

TL

TL

TL

TL

TL

LB

1

2

Gravel

Tarmac

StoneBench

Moor

Moor

Moor

Gravel

BrokenGround

Lad

Lad

Concrete

Lad

Tarmac

Tarmac

Tarmac

Gravel

ConcreteSlipway

RoughGrass

Lad

Lad

Lad

Lad

Lad

Lad

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

FenFen

Fen

Fen

Fen

Fen

Fen

FenFen

Fen

Fen

Fen

Fen

Fen

Fen

© Crown Copyright 2007. All rights reserved. Licence number 100020449

FB

Dunara

Loch View

Path

(um

)

Whitehouse

Cottage

1

BM 21.94m

Kyle Rona

Sand Mine

Kyle

TCB

Shore

LB

Cao

las

na h

-Aird

e

Hall

Fall

8.8m

St Kilda

A1

A2

A3

A4

A5

F6

F7

F8

F9

F10

F11

F12

F13

F14

F15

F17

F18

F19

F20

F21

D1

D2

D3

D4

D5

D6

R1

F16

F1

F2

F3

F4

F5

R2

MHWS +24.00

MLWS +

A

AB

B

REFER TOPLAN BELOW

HERITABLE TITLE *

CROWN ESTATES *

SEAWARD HARBOUR AREA *

LEGEND

* FOR INFORMATION ONLYDETAILS TAKEN FROM CMAL DRAWINGNo. GB8428/MM/113, TITLE DEED PLANDATED 28/11/11.

NOTES

DRAWING No.

DRAWN CHECKED APPROVED

DATE

TITLE

REVISIONS

REV DATE DESCRIPTION CHK APP

REVISION

BY

HaskoningDHV UK Ltd.

PROJECT

c

REPRODUCED FROM ORDNANCE SURVEY MAPS WITH PERMISSIONFROM THE CONTROLLER OF HM STATIONERY OFFICE. CROWNCOPYRIGHT RESERVED. LICENCE No. 100023422 2007.

CLIENT

DO NOT SCALEDRAWING No.

SCALE AT A1 CAD REF.

HASKONINGDHV UK LTDMARITIME & WATERWAYS

10 Bernard StLeith, Edinburgh

EH6 6PPTel +44 (0) 131 555 0506Fax +44 (0) 131 555 0502

info.edinburgh@rhdhv.com www.royalhaskoningdhv.com

PLAN ON SLIPWAYSCALE 1:250

ELEVATION ON SLIPWAYSCALE 1:200

EXISTINGGENERAL LAYOUT

PB4151-1000

PB4151-P-1000

PB4151-P-1000

P1

AS SHOWNOCT '15

JM

LOCHALINE SLIPWAY

SECTION A-ASCALE 1:100

SECTION B-BSCALE 1:100

P1 NOV '15 - JM - -

KEY PLANSCALE 1:2500

12

Appendix B – Proposed Layout

7 March 2017 PB4151/TN01/303294/Newc

MH

WS

+

24.00

MLW

S +

A

A

B

B

150

0762

73

8

1 1

2

2

ROCK FILL

ROCK FILL

ROCK ARMOUR

SLOPE

ROCK FILL

ROCK ARMOUR

SLOPE

FABRIFORM

MATTRESS

BED LEVEL

M.H.W.S +2.4 OD

0.00 OD

APPROX M.L.W.S

M.H.W.S +2.4 OD

0.00 OD

APPROX M.L.W.S

SECTION B-B

SCALE 1:100

SECTION A-A

SCALE 1:100

A

A

B

B

M.H.W.S +2.4 OD

0.00 OD

APPROX

M.L.W.S

NAVIGATION

LIGHT

M.H.W.S +2.4 OD

0.00 OD

APPROX

M.L.W.S

SECTION 1-1

SCALE 1:200

SECTION 2-2

SCALE 1:200

RE

FE

R T

O E

LE

VA

TIO

N 1-1

RE

FE

R T

O E

LE

VA

TIO

N 2-2

NOTES

DRAWING No.

DRAWN CHECKED APPROVED

DATE

TITLE

REVISIONS

REV DATE DESCRIPTION CHK APP

REVISION

BY

HaskoningDHV UK Ltd.

PROJECT

c

REPRODUCED FROM ORDNANCE SURVEY MAPS WITH PERMISSION

FROM THE CONTROLLER OF HM STATIONERY OFFICE. CROWN

COPYRIGHT RESERVED. LICENCE No. 100023422 2007.

CLIENT

DO NOT SCALE

DRAWING No.

SCALE AT A1 CAD REF.

HASKONINGDHV UK LTD

MARITIME & WATERWAYS

10 Bernard St

Leith, Edinburgh

EH6 6PP

Tel +44 (0) 131 555 0506

Fax +44 (0) 131 555 0502

info.edinburgh@rhdhv.com

www.royalhaskoningdhv.com

PLAN ON SLIPWAY

SCALE 1:200

PROPOSED

GENERAL LAYOUT

PB4151-1100

PB4151-1100

PB4151-1100

P1

AS SHOWNOCT '15

GIC

LOCHALINE SLIPWAY

P1

NOV '15

- JM - -

13

Appendix C - Isopachyte Chart

7 March 2017 PB4151/TN01/303294/Newc

Fen

Fen

Fen

Fen

Fen

Fen

FenFen

Fen

Fen

Fen

Fen

Fen

FenFen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Fen

Lad

Lad

Lad

J/Box

Lad

Lad

Lad

M/R 1.0m

Lad

Lad

Lad

Bus

Shelter

ConcreteRamp

Steps

Moor

Moor

Moor

DrainageChannel

StoneBench

Stone Wall 0.8m

2

1

LB

TL

TL

TL

TL

TL

TL

TL

KO

KO

MP

Culv

Culv

Culv

Culv

Dr

P

P

P

RS

RS

RS

RS

RS

LP

LP

LP

LP

SC

SC

SC

Lad

Lad

Lad

Lad

Moor

MOOR

MOORMOORMOORMOORMOOR

167900E167900E

167950E167950E

168000E168000E

168050E168050E

168100E168100E

168150E168150E

168200E168200E

744600N744600N

744650N 744650N

744700N744700N

744750N 744750N

744800N744800N

744850N 744850N

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.00.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0 0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

Survey Parameters & Equipment

1:1 @ A1

CDT

24th February 2017

1:500A5390_23

18th January 2017

KEMM

1 of 1

Legend

Notes:

Web: www.aspectsurveys.com

Tel : 01294 313399 Fax : 01294 313389

spect

IrvineKA12 OHW

Ballot Road

E-mail: mail@aspectsurveys.com

Thornhouse Business Centre

Coloured Depth Bands:

Survey Vessel:

Chart Datum is 2.10m below Ordnance Datum.

Positioning System:

The datum was established using corrected OS Rinex data and post-processed using Trimble BusinessCentre Software.

GPS Correction Source:

Echosounder:

Grid System:

Geoid Model:

Semi Major Axis:

Flattening (1/f):

Transformation Paramaters:

Vertical Datum (Hydrographic):

Vertical Datum (Topographic):

Distance Unit:

Positioning System Spheroid & Datum:

Motion Compensator:

Spheroid:

10 20 3050 40 50

Scale: 1 cm = 5.00 Meters

0.91.93.54.5

FORE STREET

PORT GLASGOW

PA14 5EQ

CALEDONIAN MARITIME ASSETS LTDMUNICIPAL BUILDINGS

HIGHLANDS

LOCHALINE

LOCHALINE SLIPWAY

LEVEL DIFFERENCE DRAWINGBETWEEN SURVEYS UNDERTAKEN 17/06/13 & 18/01/17

Technical Note 01 - Coastal Processes AssessmentTechnical Note 01 - App ATechnical Note 01 - Coastal Processes AssessmentTechnical Note 01 - App BTechnical Note 01 - Coastal Processes AssessmentTechnical Note 01 - App C