Midlothian Esks Barrier Easement Project Phase...

Midlothian Esks Barrier Easement

Project Phase 2a

Project Report

Client: River Forth Fisheries Trust

Reference: WATPB4209R001F01

Revision: 01/Final

Date: 10/05/2016

10/05/201610/05/2016 ESK PHASE 2A WATPB4209R001F01 1

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Document title: Midlothian Esks Barrier Easement Project Phase 2a

Document short title: Esk Phase 2a

Reference: WATPB4209R001F01

Revision: 01/Final

Date: 10/05/2016

Project name: Midlothian Esks Barrier Easement Project Phase 2a

Project number: PB4209

Author(s): James Davill, Carina Agnew and Clare Rodgers

Drafted by: James Davill and Clare Rodgers

Checked by: Carina Agnew

Date / initials: 10/05/16

Approved by: Edward Sorfleet

Date / initials: 12/05/2016

Classification

Open

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permission, for any purposes other than that for which they were produced. HaskoningDHV UK Ltd. accepts no

responsibility or liability for these specifications/printed matter to any party other than the persons by whom it was

commissioned and as concluded under that Appointment. The quality management system of HaskoningDHV UK Ltd.

has been certified in accordance with ISO 9001, ISO 14001 and OHSAS 18001.

No part of these specifications/printed matter may be reproduced and/or published by print, photocopy, microfilm or

by any other means, without the prior written permission of HaskoningDHV UK Ltd. or our client; nor may they be

used, without such permission, for any purposes other than that for which they were produced. HaskoningDHV UK

Ltd. accepts no responsibility or liability for these specifications/printed matter to any party other than the persons by

whom it was commissioned and as concluded under that Appointment. The quality management system of

HaskoningDHV UK Ltd. has been certified in accordance with ISO 9001, ISO 14001 and OHSAS 18001.


Executive Summary

The North Esk and South Esk are rivers with excellent areas of upstream habitat for fish and

other species, where the use of these habitats is limited by historic weir structures which act as a

barrier to fish migration and impedes the movement of sediment downstream. The River Forth

Fisheries Trust and the Scottish Environment Protection Agency (SEPA) have prioritised two

weir structures for mitigation in this catchment. Montagu Bridge Weir and Dalkeith Weir are

considered to be the most downstream impassable barriers on the North and South Esk rivers

respectively. Enabling fish migration upstream of these sites was identified as the first step to

helping fish access upstream reaches of the Midlothian Esks system.

The design stage followed an initial feasibility and optioneering study which identified a preferred

option to address fish migration and sediment movement issues at these two impassable weirs.

These options were consulted on widely through a series of public engagement events across

the local area. The design stage has built upon the work undertaken during the feasibility and

optioneering study to develop the preferred option for each site into feasible and effective

engineering designs, accompanied by supporting assessments and licences that will be needed

to deliver each option on the ground.

A series of desk and site-based surveys and investigations were undertaken to inform the design

process for each site. These included topographic surveys, ecological surveys, sediment

sampling, assessment of utilities records and ground conditions, at each site. This information

was used to model the existing conditions at each site and then conditions following

implementation of the proposed designs to ensure that the most appropriate design for each site

is progressed.

Dalkeith Weir

Dalkeith Weir (Figure 1) has been in place at this location for over 100 years, associated with a

former saw mill (the mill lade is still evident). The preferred option identified for this weir was full

weir removal as this would restore the full range of natural ecological, hydrological and

geomorphological processes at this site.


Figure 1 - Dalkeith Weir

The final design for Dalkeith Weir is to remove the weir down to bedrock across the majority of

the channel width, with the ends of the weir left in place to become the river bank retaining wall.

The channel walls immediately downstream and adjacent to the weir will be repaired to ensure

that they are in good condition. The river will also be re-profiled for 200m upstream of the weir

to ensure a smooth gradient. An artist’s impression (see Figure 2) has been produced to show

the removal of Dalkeith Weir.

Figure 2 - Dalkeith Weir Removal Visualisation


Montagu Bridge Weir

Montagu Bridge Weir (Figure 3) has been in place at this location for over 200 years,

constructed as part of the Montagu Bridge structure and landscaping of the grounds of Dalkeith

Palace. The listed building “Dalkeith Park, Montagu Bridge including Cauld” (Category A)

includes the weir (this is the cauld). Heritage considerations have therefore been a significant

factor in developing the design of an appropriate solution at this weir that is acceptable to the

main stakeholders (including the landowner, Buccleuch Estates, and Historic Environment

Scotland). The preferred option identified for this weir was to retain the weir structure and modify

the weir in a way that is sensitive to the surrounding landscape in order to enable fish to travel

upstream. This could be done by either creating a shallow gradient ramp made from rock

downstream (a rock ramp), or by installing a series of smaller weirs to raise water levels in a

series of steps downstream (pre-barrages).

Figure 3 - - Montagu Bridge Weir

The final design for Montagu Bridge Weir is a rock ramp, of width 4m, to be built on the left bank

(looking downstream) of the North Esk from Montagu Bridge Weir for 65m downstream. The

ramp will contain carefully arranged boulders that will break up the flow, creating a diverse range

of flow depths and velocities that different fish native species can use to migrate upstream. Due

to its length, a pool will be built into the rock ramp for fish to rest in as they navigate the ramp.

Scour protection to the banks will be placed downstream made from large boulders, and a

resting pool will be created at the toe of the ramp. An artist’s impression (see Figure 4) has

been produced to show the implementation of the rock ramp to facilitate fish passage over the

Montagu Bridge Weir.


Figure 4 - Montagu Bridge Rock Ramp Visualisation

This design report will be used to support the River Forth Fisheries Trust during the consenting

and funding application process for these sites in the Midlothian Esks catchment and during the

build phase of work.

Building these designs at Dalkeith Weir and Montagu Bridge Weir is an important step towards

addressing the issues of fish migration and sediment movement at these barriers in order to

create a healthier and more resilient river ecosystem for the future in the Midlothian Esks.


Table of Contents

1 Introduction 11

1.1 Purpose of this report 11

1.2 Background to the project 11

1.3 Proposed designs 12

1.3.1 Dalkeith Weir 12

1.3.2 Montagu Bridge Weir 13

2 Dalkeith Weir Site Conditions and Constraints 15

2.1 Surveys Undertaken 15

2.2 Topography of the site 15

2.3 Utilities Service Search 16

2.4 Geotechnical investigations 17

2.5 Sediment Characterisation 18

2.5.1 Sediment Sampling 18

2.5.2 Wolman Walk (Pebble Count) 19

2.6 Ecological Survey 19

2.7 Initial Heritage Assessment and Consultation 21

2.8 Early Contractor Involvement 23

2.9 Hydraulic Modelling 24

2.10 Aquatic Ecology 26

2.11 Licences and Permits 26

2.11.1 CAR Licence Application 26

2.11.2 Planning and EIA 26

2.11.3 Listed Building Consent 27

2.11.4 Conservation Area Consent 27

3 Montagu Bridge Site Conditions and Constraints 28

3.1 Surveys Undertaken 28

3.2 Topography of the site 28

3.3 Utilities Service Search 29

3.4 Geotechnical investigations 30

3.5 Sediment Characterisation 32

3.5.1 Sediment Sampling 32

3.5.2 Wolman Walk (Pebble Count) 34

3.6 Ecological Survey 35

3.7 Initial Heritage Assessment and Consultation 36

3.8 Early Contractor Involvement 37



3.10 Aquatic ecology 39

3.11 Licences and Permits 39

3.11.1 CAR Licence Application 39

3.11.2 Planning Permission 40

3.11.3 EIA Screening Request 41

3.11.4 Listed Building Consent 41

4 Dalkeith Weir Design 42

4.1 Design approach 42

4.2 Final Design Hydraulic Model Results 43

4.2.1 Hydraulic Modelling 43

4.2.2 Sediment Transport Modelling 45

4.2.3 Flood Risk 48

4.3 Final Design 50

4.3.1 Downstream channel wall 50

4.3.2 Upstream Channel 52

4.3.3 Weir Removal 52

4.3.4 Construction Approach 53

4.3.5 Finishes and reinstatement 53

4.4 Summary of Option 54

4.5 Key Risks 54

5 Montagu Bridge Weir Design 55

5.1 Option Refinement 55

5.2 Design Approach 58

5.2.1 Operational Window 59

5.2.2 Hydraulic Criteria 60

5.2.3 Rock Ramp 60

5.2.4 Resting Pool 61


5.3.1 Hydraulic Performance 62

5.3.2 Flood Risk 65

5.4 Final Design 67

5.4.1 Rock Ramp 67

5.4.2 Resting Pool 67

5.4.3 Retaining Wall 68

5.4.4 Notch in the Weir 68

5.4.5 Downstream Channel Works 68

5.4.6 Finishes and reinstatement 69

5.4.7 Safety Considerations 70

5.5 Sediment Management Plan 70

5.6 Summary of Design 71

5.7 Key Assumptions 71


5.8 Key Risks 71

6 Information to support the contractor 72

7 Conclusion and Recommendations 73

7.1 Conclusion 73

7.1.1 Dalkeith Weir 73

7.1.2 Montagu Bridge Weir 73

7.2 Recommended Next Steps 73

7.2.1 Licences and Permits 73

7.2.2 Vegetation Clearance 74

7.2.3 Photographic Weir Surveys 74

7.2.4 Appointing a Contractor 74

7.2.5 Construction Stage 75

7.2.6 Future Monitoring of Montagu Bridge Weir Fish Pass 75

Appendix A – Site Investigation Data A

A1 – Topographic survey A

A2 – Ecology Survey A

A3 – Sediment Sampling A

A4 – Geophysical Survey A

A5 – Historic Borehole logs A

A6 – Sections and utilities A

Appendix B – Desgin Technical Notes B

B1 – APEM Design Note B

B2 – Montagu Bridge Weir Design Note B

Appendix C – Hydrualic Modelling C

C1 – Hydraulic Modelling C

Appendix D – Outline Design D

D1 – Outline Design D

D2 – Cost Estimate D

Appendix E – Licences and Permits E

E1 – Heritage Report E

E2 – Draft CAR Licence Applications E

E3 – Draft Planning Application (Montagu Bridge Weir) E

E4 – Visualisations E

E5 – Draft Listed Building Consent (Montagu Bridge Weir) E

E6 – Draft Conservation Area Consent (Dalkeith Weir) E


Appendix F – Construction Drawings F

F1 - Construction Drawings F

F2 - CDM Hazard Log F

Appendix G – Pre-construction information G

G1 - Pre-construction information G

Appendix H – CDM 2015 Letters H

H1 – CDM 2015 Appointment Letters H

Appendix I – Sediment Manegment Plan I

I1 – Sediment Management Plan I

Appendix J – Communications Log J

J1 – Communications Log J


1 Introduction

1.1 Purpose of this report

The purpose of this project report is to summarise the main design considerations and

assumptions made during the development of the barrier easement designs for Dalkeith Weir

and Montagu1 Bridge Weir on the Midlothian Esks. The supporting information gathered during

the course of the project that has been used to develop the design has been summarised within

this report; the technical reports have been provided in full in the relevant appendices. This

report is to be used to support the River Forth Fisheries Trust during the consenting and funding

application process for these weirs in the Midlothian Esks catchment.

1.2 Background to the project

The River Forth Fisheries Trust and SEPA have identified a need to address issues caused by

historic weir structures along the North and South Esks. To date, thirteen weirs on the main

stems of the North and South Esks have been prioritised where action is needed to make the

structures passable to fish, restore river sediment processes and improve the health of water

bodies under the Water Framework Directive (WFD). A Feasibility and Optioneering Study

(Royal HaskoningDHV - Midlothian Esks Barrier Easement Project FINAL_220715) was

undertaken in 2015 for Phase 1 of the Midlothian Esks Barrier Easement Project to understand

the opportunities and constraints at each site and recommend appropriate solutions. A recent

walkover survey by the River Forth Fisheries Trust has identified further barriers in the wider

Esks catchment that are impassable to migratory fish.

The Feasibility and Optioneering study appraised these thirteen weirs and advised on the

preferred option to be implemented at each site. A combination of site and desk-based activities

were undertaken to develop a strong understanding of each barrier individually and within the

context of the river catchment as a whole. This included detailed geomorphological appraisal of

the historic changes at each site and likely responses to barrier removal/ modification, alongside

a series of stakeholder events held to raise public awareness and gather feedback on potential

options.

This comprehensive understanding of baseline site conditions, opportunities and constraints for

barrier removal or modification was then used to discuss, prioritise and provide cost estimates

for the options available to improve fish passage and restore channel connectivity for each weir.

In discussion with over 50 local stakeholders, the full range of potential options were evaluated

for each site and preferred options identified which provide the most complete restoration of

hydrological, geomorphological and ecological processes feasible for each barrier.

Two weirs were identified as high priority for barrier easement works in this catchment: Dalkeith

Weir, the most downstream impassable barrier on the South Esk, and Montagu Bridge Weir, the

most downstream impassable barrier on the North Esk. Enabling fish migration upstream of

1 Also spelled Montague in some sources, but for the purposes of this report we will use Montagu.


these sites was identified as the first step to helping fish access upstream reaches of the

Midlothian Esks system.

This design stage is an important part of the work to address the issues of fish migration and

sediment movement at these barriers, in order to create a healthier and more resilient river

ecosystem for the future in the Midlothian Esks. SEPA is a key project partner and funder in

delivering this Water Environment Fund (WEF) project to improve WFD status.

1.3 Proposed designs

1.3.1 Dalkeith Weir

Dalkeith Weir is located on the South Esk a short distance upstream of the A6106 Newmills

Road bridge in Dalkeith, near Edinburgh in Scotland. Dalkeith Weir has been in place at this

location for over 100 years, associated with a former saw mill (the mill lade is still evident).

Dalkeith Weir is the most downstream weir impassable to fish on the South Esk and has been

prioritised for mitigation. Although the weir has a baulk fish pass, visible in Figure 5, it is not

effective and the weir is a significant barrier to most fish. Eels and lamprey may find a route over

a shallow section of the weir at low flows, although most would be delayed below the weir for

much of the time.

Figure 5 - Dalkeith Weir in November 2015.

For Dalkeith Weir, the proposed solution identified through the options appraisal process was full

weir removal as this would restore the full range of natural ecological, hydrological and


geomorphological processes at this site. The main limiting factors identified were the potential

for upstream bank erosion and downstream risk to the road bridge, both of which required

further investigation during the design phase.

1.3.2 Montagu Bridge Weir

Montagu Bridge Weir is located on the North Esk in Dalkeith Park, to the north of Dalkeith, near

Edinburgh in Scotland. Montagu Bridge Weir has been in place at this location for over 200

years, constructed as part of the Montagu Bridge structure and landscaping of the grounds of

Dalkeith Palace.

Montagu Bridge Weir is the most downstream weir impassable to fish on the North Esk and has

therefore been prioritised for mitigation. The weir is considered a complete barrier to all fish as

the head drop is too great for fish to jump the weir and the vertical drop could not be ascended

by eel or lamprey.

Figure 6 - Montagu Bridge Weir.

The listed building “Dalkeith Park, Montagu Bridge including Cauld” (Category A) includes the

weir (this is the cauld). This was the biggest factor governing selection and design of an

appropriate solution to improving fish passage at this weir that is acceptable to the main

stakeholders (including the landowner, Buccleuch Estates and Historic Environment Scotland).

For Montagu Bridge Weir, the proposed solution identified through the options appraisal process

was some form of visually sympathetic modification of the weir structure. The two options

identified for modification were either the use of pre-barrages, or a rock ramp (see Figure 7 for


examples of these types of fish pass). It is noted that neither of these options would address

sediment transfer issues, for which a Sediment Management Plan may be required. Weir

removal was not considered acceptable at Montagu Bridge Weir as the weir is a Category A

listed structure and important part of the national and local heritage. These options were refined

further following site survey work during the design phase, as discussed in Section 3.

Figure 7 – Examples of preferred options: series of stone pre-barrages (left) and a rock ramp (right).


2 Dalkeith Weir Site Conditions and Constraints

This section of the report details site conditions and constraints that were evaluated during the

design phase for Dalkeith Weir.

2.1 Surveys Undertaken

A range of surveys were undertaken to inform the design development which define the site

parameters, conditions and constraints. The following surveys were undertaken at Dalkeith Weir

and have been summarised in the following sections, with the technical reports provided in the

appendices of this report:

• Topographic survey (Appendix A1 and A6);

• Ecological Survey (Appendix A2);

• Sediment Sampling and Pebble Count (Appendix A3);

• Assessment of borehole records (Appendix A5);

• Site Walkover by project team and Contractor (Early Contractor Involvement); and

• Statutory undertaker utilities records (Appendix A6).

2.2 Topography of the site

Royal HaskoningDHV procured a topographic survey that was used to produce a tailored

hydraulic model and inform the detailed design. The topographic survey was undertaken

(November 2015) by our sub-consultant cbec eco engineering. The survey provided ground

levels around the weirs as well as the profile of the river bed to give confidence to the modelling

results. Topographic survey information can be seen in Appendix A1 and Appendix A6.

Appendix A6 contains a long and cross sections through the river.


Figure 8 - Topographic survey point data locations at Dalkeith Weir. Full image available in Appendix A1.

The following key information for the design was gathered through the topographic survey at

Dalkeith Weir:

• Weir crest level 34.67mAOD.

• Scour hole downstream of weir 30.442mAOD.

• Downstream of weir river bed is approx. 31.8mAOD.

• 100m upstream of the weir the channel bed level is approx. 33.8mAOD.



2.3 Utilities Service Search

A desk based utilities search was carried out for this design stage of the project by requesting

records from statutory undertakers. These services have been marked on the topographic

survey, outline design and construction drawings (see Appendix A6, Appendix D1 and

Appendix F1). Prior to commencing any site work it is recommended the contractor review this

information and re-request the data if more than six months has passed.


There were limited services in this area; the services that will provide a restriction on

construction activities are those located in the entrance to the site. These will require protection

during the construction phase, as marked on the design drawings (see Appendix F1).

2.4 Geotechnical investigations

The British Geological Survey collates data on the geology of Great Britain. We used their

website to see if there was existing information that would give us confidence to design the

works without undertaking any geotechnical testing. Figure 9 below shows that existing

boreholes from the 1970’s are available in the vicinity of the weir.

Figure 9 - Historic Boreholes near Dalkeith Weir from the British Geological Society.

The borehole logs are available in Appendix A5. The borehole logs showed that the bedrock

levels varied between 31mAOD and 32mAOD in the area adjacent to the river.

The access to the weir and adjacent banks is very restricted. The banks are steep and

vegetated with mature trees, which within a Conservation Area, would require agreement with

Midlothian council before they could be removed. The river channel upstream is heavily silted

and our topographic surveys had difficulty undertaking a safe survey of the crest . Further, there

is a significant scour pool downstream of the weir, which makes access and inspection difficult.

With the information from the existing boreholes, it was decided that the significant cost and

risks associated with undertaking new boreholes or coring of the weir would not be possible until

the construction stage.


2.5 Sediment Characterisation

2.5.1 Sediment Sampling

To assess the quality of the River Esks shallow sediment, samples were collected from three

sites in the vicinity of the barrier from a depth between 0 – 0.45m (see Table 1 for further

details). The laboratory results can be seen in Appendix A3. Sediment coring was undertaken

on the 2nd December 2015. Due to high flows, coring was limited to the right bank with two

individual sampling locations selected upstream of the weir, and a further sample location

downstream of the weir (as a control). A total of 8 jars of sediment (2 x 500ml, 2 x 250ml and 4 x

60ml) were collected from each location, at varying depths.

Location description Alcontrol

Reference

Co-ordinates Date Time Depth range

X Y

South Esk - upstream of

Dalkeith Weir 4 33555 67042 02.12.15 09.00 0-20cm

South Esk - upstream of

Dalkeith Weir 5 33578 67036 02.12.15 10.30 0-30cm

South Esk - downstream

of Dalkeith Weir &

Bridge 6 33673 67215 02.12.15 13.15 0-45cm

Table 1 - Details of samples taken

The samples were analysed by Alcontrol laboratories. In the absence of accepted local sediment

quality standards, the results were reviewed using the LQM/CIEH S4ULs for Human Health Risk

Assessment standards (Land Quality Press, 2015).

Land Quality Management (LQM) and the Chartered Institute of Environmental Health (CIEH)

developed Suitable For Use Levels (S4ULs) to support the assessment of potential risks posed

to human health by contaminants in soil. The benchmark concentrations have been derived in

accordance with UK legislation and national policy and are based on the concept of minimal or

tolerable risk. For each contaminant, LQM/ CIEH S4Uls have been calculated for six land use

scenarios. It was assumed that the Public Parks land use values will be most appropriate for

purpose of this assessment. Soil Organic Matter (SOM) content was calculated using Fraction

Organic Carbon (FOC). A summary of the findings is presented in Table 2.


Site Alcontrol

Reference SOM [%}

Petroleum

Hydrocarbons

(BTEX)

Total Petroleum

Hydrocarbons

(PAHs)

Metals

4 (Dalkeith) 4 1% Not exceeded Not exceeded Not exceeded

5 (Dalkeith) 5 2.5% Not exceeded Not exceeded Not exceeded

6 (Dalkeith) 6 1% Not exceeded Not exceeded Not exceeded

Table 2 - Sediment Sample analysis for Dalkeith Weir.

2.5.2 Wolman Walk (Pebble Count)

A Wolman Walk survey was carried out to characterise particle size distribution within the river at

Dalkeith Weir. This information was used as an input into the hydraulic model.

The Wolman-walk pebble count methodology (Wolman, 1954) was used to characterise the

sediment. This involved the random sampling of a minimum of 100 substrate particles, each

sample in a grid across a discrete sedimentary unit (e.g. bar features or uniform section of

channel bed). The size of the particles are measured using a ‘gravelometer’ sediment sampler,

consisting of a handheld template with different sized square apertures ranging from sand (<2

mm) to boulders (>256 mm).

The results of the survey are shown in spatial data in Appendix A3, showing the data as D-

values and a substrate map. The findings of this survey are summarised in Table 3 below.

River Sample D50 D84 x y

South Esk 9 27.3 55.36 333660 666559

South Esk 10 35.79 66.89 333679 666713

South Esk 11 30.96 72.67 333647 666828

South Esk 12 62.35 115.33 333617 666869

South Esk 13 32.65 58.57 333554 666920

South Esk 14 43.3 77.87 333502 666953

South Esk 15 81.73 161.43 333703 667249

Table 3 - D50 and D84 values recorded in the river around Dalkeith Weir.

2.6 Ecological Survey

Royal HaskoningDHV procured ecological services from Practecology who undertook an

ecological assessment to inform designs for improvements to fish passage and ease of

sediment transfer at Dalkeith Weir. This incorporated a desk-based review of available data

sources and a field survey. The ecological field assessment was carried out in November 2015

and covered 250m upstream and 500m downstream of Dalkeith weir and across a 100m wide


riparian corridor centred on the mid channel of the river. An extended survey length downstream

was considered in the event the proposed works led to an increase in water levels. The findings

of the ecological assessment are summarised in the sections below and provided in full in the

report Practecology (2015) Midlothian Esks Barrier Easement Project – Phase 2a: Ecological

Assessment of Dalkeith Weir in Appendix A2.

Protected habitats and species

Two statutory designated sites where identified, Dalkeith Oakwood SSSI and the Firth of Forth

SPA, 1.16km and 6.2km from site respectively. The removal of Dalkeith Weir is not considered

to have any impact on these statutory protected habitats.

Records obtained from online sources and The Wildlife Information Centre indicated the

presence of a number of protected and notable species within 1.5km of Dalkeith Weir. However,

weir removal will be limited in scale and likely to affect only those habitats and species which

occupy the river and its riparian corridor close to the works area.

Dalkeith Bridge and a small culvert close to a private access road have some potential to

support roosting bats. It is considered unlikely that bats will occupy gaps in the retaining walls

adjacent to the weir due to their proximity to the waterline and the presence of overhanging

vegetation. However, if gaps are to be filled to stabilise the wall or remove opportunities for

nesting birds then it is advised that an assessment with an endoscope should be carried out first.

If signs suggest bats could be present then a specific bat survey would be required.

Figure 10 - Dalkeith Bridge


An otter holt was identified 270m downstream of the weir and will require further monitoring if the

removal of the weir leads to an increase in water level such that it is no longer usable. (Note

modelling shows no change in velocities and depths downstream of the weir once it is removed).

Trees and shrubs must be removed from the works area and route of access ahead of the bird

breeding season to ensure that works are not delayed as a result of finding nesting birds on site.

Blocking gaps in the stonework of the retaining walls, provided no signs of bats are present, is

also recommended, particularly as kingfisher have been observed in the area. Monitoring the

river prior to the commencement of works may also inform the likely location of kingfisher nests

and allow for more targeted mitigation. It is advised that ecological surveys are repeated if more

than six months passes before works commence.

Invasive Species

Both Himalayan balsam and Giant hogweed were found within the survey area along the River

South Esk. During the construction phase a Construction Environmental Management Plan

(CEMP) detailing biosecurity measures should be provided by the main contractor and

implemented during works to stop the spread of these plants and contaminated soil.

Pollution Prevention

The CEMP should also cover what pollution prevention and control measures will be adopted

given the need for in-stream works. Avoiding the refuelling of plant on site, keeping all fuels in a

securely bunded area and having a spill kit on hand for the duration of works is also

recommended.

2.7 Initial Heritage Assessment and Consultation

There are significant heritage considerations and constraints within this project and Midlothian

Council confirmed that Conservation Area Consent would be required for the removal of Dalkeith

Weir. A Heritage Statement was prepared to support the Conservation Area Consent and this

report can be found in Appendix E1.

Dalkeith Weir lies within the northern limits of Newbattle Conservation Area, and although

complete removal of the structure will impact the existing historical and functional associations

with Woodburn Saw Mill Lade and the industrial setting along this part of the river, it is not

considered to impact the character or importance of the Conservation Area. However, in

consideration of the alteration to the industrial setting of this part of the river, it is recommended

that a photographic survey is undertaken of Dalkeith Weir and its surroundings prior to any

demolition works, to provide a record.


Figure 11 – Mill Lade at Dalkeith Weir

The proposed works also include re-profiling the river channel upstream of the weir, topsoil

stripping and removal of some vegetation along the east/south bank of the river. These works

may have an impact on any buried archaeological remains, which are at present unknown, and

therefore it is recommended that an archaeological watching brief is undertaken during any

topsoil stripping required for the siting of the compound and bank stability works, and a finds

protocol is put in place in the event that artefacts are recovered during the excavation of the river

bed. We are advising a precautionary approach and the need for a watching brief will be

confirmed with Midlothian Council following their consideration of the Conservation Area

Consent application. Further detail can be found in the Heritage Statement in Appendix E1.

The removal of some vegetation along the east/south river bank may also have some localised

impact on the formal garden setting of Old Mill House and therefore it is recommended that

these trees are replaced with similar species, of a similar size where possible.

Other mitigation measures prior to and during construction include toolbox talks conducted at the

start of construction in order to highlight the location and significance of the designated and non-

designated built heritage assets, and exclusion zones are clearly demarcated around the Old

Mill House and Woodburn Saw Mill Lade in order to prevent any accidental damage during

construction.


2.8 Early Contractor Involvement

Royal HaskoningDHV partnered with Lumsden and Carroll Civil Engineering (L&C) to provide

early contractor involvement (ECI) on this project. ECI gives a contractor’s view of the site and

identifies access, buildability and site restraints at an early stage.

L&C noted there was limited access to the site, with the only access through the driveway to the

Old Mill House (see 12). This would require the site compound to be located within the grounds

of the Old Mill House. L&C recommended traffic management controls for exit/entry to the site

and protection for services in the private access road.

L&C highlighted that to access the weir and river, there would have to be vegetation and tree

removal. It was proposed access to the river channel should be from upstream of weir where

there were less mature trees and vegetation.

Figure 12 - Driveway to the Old Mill House.

When removing the weir, the retaining walls adjacent to the weir will be affected as they are

connected to the weir structure. Removing the weir will require work to be undertaken on the

channel walls immediately downstream of the weir. L&C suggested the repairs to the

downstream channel walls could be done using a new piled wall and face the piles with cladding

stone. Due to the high bedrock level this was not considered feasible.

L&C input was used to develop an outline construction methodology for the CAR licence and

undertook a pricing exercise creating a bill of quantities for the proposed construction work (see

Appendix D2, note this appendix should be considered as Commercially Sensitive).


2.9 Hydraulic Modelling

The project team assessed the river hydrology to develop an understanding of the river flows.

River gauge data was requested from SEPA and used to calculate flows at Dalkeith Weir.

The closest gauge to the Dalkeith Weir study site is the SEPA gauge at Cowbridge (333881E,

667615N), only 500m downstream of the downstream survey boundary. This gauge has only a

short flow record however, and so peak flow estimates from the gauge data are not reliable for

long term predictions. However, the gauge is suitable for providing low flow estimates, and the

Q95%, Q50% and Q10% daily flows are all available.

For flood flows, the ReFH2 software and FEH web service was used to provide flow peaks and

flow hydrographs for hydraulic modelling and sediment transport/bed mobility modelling. The

flows are shown in Table 4.

Flow statistic Flow [m3/s] Hydraulic significance

50% daily 1.54 Fish passage

10% daily 4.91 Fish passage

2 year return 34.81 Channel forming

200 year return 109.30 Design flood

Table 4 - Hydrology from the Cowbridge Gauge (low flows) and ReFH2

After completion of the topographic survey, a 2D surface Digital Elevation Model (DEM) of the

existing weir and surrounding land was built in AutoCAD. The DEM was used to input into a

hydraulic model of the existing river situation. This provided a baseline to compare the weir

removal against, to understand the impact of the changes. A report on the modelling is located in

Appendix C1.

The design stage of this project required an iterative process between the engineering team and

the hydraulic modellers to ensure that the design details were added to the model and used to

calculate the effect on the river. Model runs were undertaken at a range of flows that can be

seen in detail in the modelling report. Further detail of the design process can be seen in

Section 4 of this report.


Figure 13 - Dalkeith Weir bed stress for the existing situation. Full image available in Appendix C1.

The modelling work was undertaken by sub-consultants cbec eco engineering with Royal

HaskoningDHV’s principal hydraulic modeller providing expert reviews. Also, our project

geomorphology expert worked with cbec during the geomorphology assessment of the effect of

removing the weir. The modelling data and reports can be found in Appendix C1.

The models produced during the design phase included:

• A 1D hydraulic model of the existing conditions;

o 1D HEC-RAS model of existing condition South Esk at Dalkeith Weir- this model

is used to act as a baseline for eventual sediment transport and flood risk

modelling;

• A 2D detailed model of the structure and design condition;

• 2D (SRH-2D) low flow (Q95%, Q50% and Q10%) and flood model (2-200 year) of South

Esk at Dalkeith Weir used for design work and as a baseline for flood risk modelling; and

• A 2D, mobile bed, sediment transport model to aid the design work by showing potential

erosion and deposition following the weir removal.

The 2D model for Dalkeith weir existing conditions, and a design condition without the weir, has

been used in the re-design of the channel upstream of the weir. Importantly, 2D hydraulic


modelling results have shown that a simple weir removal results in excessive velocities and

shear, which could lead to an unstable channel upstream. Design iterations have reduced this

high velocity proximal to the weir location, and further design iterations and modelling were

required to produce a stable channel. Further information on the model development and

resulting iterative design is provided in Section 4.

2.10 Aquatic Ecology

Royal HaskoningDHV appointed APEM to provide aquatic ecology support to the design

process. The APEM specialist visited the site and reviewed species data available from the

River Forth Fisheries Trust. APEM produced a technical design note to support the design

which can be found in Appendix B1.

River Forth Fisheries Trust provided fish catch data from various locations on the North and

South Esk. This identified that the main native migratory fish species present in the watercourse,

and of concern for fish passage, are:

• Atlantic salmon (Salmo salar);

• Sea and brown trout (Salmo trutta);

• Sea lamprey (Petromyzon marinus);

• River lamprey (Lampetra fluviatilis); and

• European eel (Anguilla anguilla).

It was considered that after the removal of the weir down to bedrock, the river would be in a

natural state. This will allow the migration of native species that would have existed within the

river before the weir was built. It is noted that due to the natural bedrock of the river this may not

result in fish passage at all river flows.

2.11 Licences and Permits

2.11.1 CAR Licence Application

SEPA has confirmed that Controlled Activities Regulations (CAR) authorisation is required for

the physical engineering works within the channel at Dalkeith Weir. The draft CAR licence

application (Forms A and E) has been provided in Appendix E2.

2.11.2 Planning and EIA

Royal HaskoningDHV sought pre-planning advice from Midlothian Council (21/10/2015). The

response was that Dalkeith Weir removal would not require a planning application, unless the

construction of any new structures in the channel would be required to mitigate the removal of

the weir. The design works require the removal of the weir, repair of existing walls, re-profiling of

the river channel, so we do not consider that planning permission is needed.

Royal HaskoningDHV also submitted an EIA Screening Request Letter (25/11/2015) to

Midlothian Council to confirm whether the proposed works will require a statutory Environmental

Impact Assessment to be undertaken. Midlothian Council confirmed (02/12/2015) that the


removal of Dalkeith Weir would not require a statutory EIA. See Appendix E3 for the screening

letter responses and pre-application advice.

2.11.3 Listed Building Consent

It should be noted that from assessing available records, Dalkeith Weir is not listed and therefore

we have not included any provision for a Listed Building Consent application for the removal of

this structure.

2.11.4 Conservation Area Consent

As identified in Section 2.7, Conservation Area Consent is required for the removal of Dalkeith

Weir. See Appendix E6 for the draft application that will be submitted to Midlothian Council for

consideration.


3 Montagu Bridge Site Conditions and Constraints

This section of the report details site conditions and constraints that were evaluated during the

design phase for Montagu Bridge Weir.

3.1 Surveys Undertaken

A range of surveys were undertaken which define the site parameters, conditions and

constraints. At Montagu Bridge Weir the following surveys were undertaken and can be found in

the appendices of this report:

• Topographic survey (Appendix A1 and A6);

• Ecological Survey (Appendix A2);

• Sediment Sampling and Pebble Count (Appendix A3);

• Geophysical Survey (Appendix A4);

• Site Walkover by project team and Contractor (Early Contractor Involvement); and

• Statutory undertake utilities records (Appendix A6).

Figure 14 - Topographic survey underway at upstream of Montagu Bridge. Photo from upstream of Montagu Bridge Weir,

3.2 Topography of the site

Royal HaskoningDHV procured a topographic survey that was used to produce a tailored

hydraulic model and inform the detailed design. The topographic survey was undertaken by our

sub-consultant cbec eco engineering. The survey provided ground levels around the weirs as


well as the profile of the river bed to give confidence to the modelling results. Topographic

survey information can be seen in Appendix A1 and Appendix A6.

Figure 15 - Topographic survey points taken at Montagu Bridge Weir. A full version of this image is available in Appendix A1.

The topographic survey revealed three important aspects compared to the estimations made

during the feasibility stage of the project:

1. The height of the weir was greater than the 1.8m estimated at the feasibility stage;

2. The downstream river channel was wider than expected; and

3. The river bed level downstream of the weir had a steeper gradient than expected.

3.3 Utilities Service Search

A desk based utilities search was carried out for this stage of the project by obtaining records

from statutory undertakers. These services have been marked on the topographic survey,

outline design and construction drawings (See Appendix A6, Appendix D1 and Appendix F1).

Prior to commencing any site work it is recommended the contractor review this information and

re-request the data if more than six months has passed.


Figure 16 - Water service at Montagu Bridge.

The obtained records show limited services in this area, with the only service running along the

access road that crosses over Montagu Bridge. However, it is suggested that the contractor

consult with the landowner to determine if they have any site records that should be considered

before breaking ground in the construction phase.

3.4 Geotechnical investigations

At Montagu Bridge Weir, geotechnical information was required for the design of the foundation

of the fish pass structure. A review of the published mapping indicates alluvial and river terrace

deposits overlying Scottish Coal Measures sandstones and mudstones. In addition the initial site

visits showed evidence of rock close to the ground surface. A scoured pool is present

immediately downstream of the weir with an ‘island’ of accreted sand, gravel and cobbles further

downstream.

A review of the British Geological Society (BGS) borehole records showed that historic data is

not available for this site. Therefore, it was decided that further geotechnical information was

required to inform the design at this weir. However, access is extremely difficult with steep sided

river banks making intrusive investigation difficult. In addition, the cost of mobilising suitable

equipment to the location of the fish pass was likely to be significant and environmental

constraints were likely to impede any works in the river bed due to it being conducted during a

sensitive period for migratory fish.

A site walkover was undertaken by a Principal Geotechnical engineer to determine the need for

further geotechnical investigation. The recommendation from this walkover was to use a


geophysical survey to determine the bedrock depth at the site. This method is non-intrusive and

requires light weight equipment to mitigate the difficult access to the site and negate the need for

intrusive in-channel working.

A geophysical survey was carried out at the location of the proposed fish pass by TerraDat in

January and March 2016 (see Appendix A4) to determine the nature of the ground at the

location of the fish pass. The geophysical survey consisted of both seismic refraction and

resistivity survey techniques, as explained in the Terradat report (Appendix A4).

The geophysical survey indicated that the ground profile in the riverbed at the location of the

proposed fish pass consisted of the following profile in order of superposition:

• A thin layer (<0.5m) of soil/organic material; which is locally absent.

• A layer of compact/dense soil or highly weathered rock which varies in thickness from

approximately 2m to 5m.

• A basal layer of competent rock; the base of which was not proven by the survey.

The ground profiles revealed by the geophysical survey techniques (P wave, S wave and

resistivity) correlated very well at the location of the fish pass. In addition it is considered that the

nature of the ground revealed by the geophysical survey was in accordance with the anticipated

ground profile from the earlier desk study research carried out at the site. Consequently it is

considered that the results of the geophysical survey are sufficiently accurate to enable an

assessment of the required excavation level for the fish pass.

The results of the geophysical survey have indicated that the nature of the ground at the

presumed level of excavation will be either dense soil or weathered rock. It is considered that the

construction of the fish pass in either of these two types of ground would be adequate in terms of

bearing capacity and settlement of the structures.

However, it is possible that the dense soil, which may be alluvial soil, may not be stable during a

significant flood event. Consequently it is recommended that the fish pass is founded at least

0.3m below the top of the weathered rock.

Figure 17 - Extract from TerraDat report (full image in AppendixA4).


The geophysical survey has indicated that the top of the weathered rock is likely to be variable

and may occur at or even above the presumed excavation level of 25mOD. However it is also

possible that locally the top of the weathered rock may be deeper than 25mOD. Figure 17

shows a dashed line (top of the S4 layer) which is the estimated to be the depth of weathered

rock. The weathered rock is around the 25mAOD mark on the left hand side of the river channel;

however this drops down to 22.5mAOD on the right hand side. As a worst case scenario the

foundation of the rock ramp would have to be built at 22.5mAOD. It is noted that the fish pass

will be designed on the left hand side of the channel where the weathered rock is closer to the

existing river bed surface.

The design will require the foundation of the fish pass to be built 0.5m into the weathered rock. It

was agreed to set the invert of the fish pass structure at 25mAOD. A further layer of mass

concrete will be placed below 25mAOD to form the foundation of the structure. In general this

will be a foundation level of 24.5mAOD; however there will be localised areas that will require a

deeper mass concrete fill.

It is recommended that the suitability of the ground at the foundation excavation level should be

confirmed by a site inspection carried out by an engineer during the works.

The full geophysical survey results can be found in Appendix A4.

3.5 Sediment Characterisation

3.5.1 Sediment Sampling

To assess the quality of the North Esks shallow sediment, samples were collected from three

sites in the vicinity of the weir from a depth between 0 – 0.45 m and further details of the survey

locations are provided in Table 5. The laboratory results can be seen in Appendix A3. Sediment

coring was undertaken on the 1st December 2015. Due to the high river flows, coring was limited

to the right bank with two individual sampling locations selected upstream of the weir, and a

further sample location downstream of the weir (as a control). A total of 8 jars of sediment (2 x

500ml, 2 x 250ml and 4 x 60ml) were collected from each location, at varying depths.


Location description Alcontrol

Reference

Co-ordinates Date Time Depth range

X Y

North Esk - upstream

of Montague Bridge 1 33350 68096 01.12.15 10.00 0-20cm

North Esk - directly

underneath Montague

Bridge 2 33368 68105 01.12.15 10.55 0-30cm

North Esk -

downstream of

Montague Bridge &

Weir

3 33371 68164 01.12.15 13.00 0-20cm

Table 5 - Details of samples taken

The makeup of sediment and lack of coarse material in the bed resulted in a maximum of

approximately 30cm of core being produced each time (sediment of a slightly coarse size acts

as a plug and limits the loss of fine sediment and silt from the instrument when it is being

extracted from the bed).

Further downstream, the nature of the bed was found to be considerably more coarse and also

consisted of bedrock, limiting the depth that the corer was able to penetrate. Organic matter was

also evident within many of the cores at this site due to proximity of the sample locations to the

river banks (constrained by high flows). This limited the size of the cores obtained as the caps

which are used to collect fine sediment cores often became clogged with leaf matter.

The samples were analysed by Alcontrol laboratories. In the absence of accepted local sediment

quality standards, the results were reviewed using the LQM/CIEH S4ULs for Human Health Risk

Assessment standards (Land Quality Press, 2015).

Land Quality Management (LQM) and the Chartered Institute of Environmental Health (CIEH)

developed Suitable For Use Levels (S4ULs) to support the assessment of potential risks posed

to human health by contaminants in soil. The benchmark concentrations have been derived in

accordance with UK legislation and national policy and are based on the concept of minimal or

tolerable risk. For each contaminant, LQM/ CIEH S4Uls have been calculated for six land use

scenarios. It was assumed that the Public Parks land use values will be most appropriate for

purpose of this assessment. Soil Organic Matter (SOM) content was calculated using Fraction

Organic Carbon (FOC). A summary of the findings is presented in Table 6 - Sediment Sample

analysis for Montagu Bridge Weir.


Site Al Control

Reference SOM [%}

Petroleum

Hydrocarbons

(BTEX)

Total Petroleum

Hydrocarbons

(PAHs)

Metals

1 (Montagu) 1 1% Not exceeded Not exceeded Not exceeded



Table 6 - Sediment Sample analysis for Montagu Bridge Weir.

3.5.2 Wolman Walk (Pebble Count)

The project work included a survey to characterise particle size distribution within the river at

Montagu Bridge Weir. This information would be used as an input into the hydraulic model.

The Wolman-walk pebble count methodology (Wolman, 1954) was used to characterise the

sediment. This involved the random sampling of a minimum of 100 substrate particles, each

sample in a grid across a discrete sedimentary unit (e.g. bar features or uniform section of

channel bed). The size of the particles are measured using a ‘gravelometer’ sediment sampler,

consisting of a handheld template with different sized square apertures ranging from sand (<2

mm) to boulders (>256 mm).

The results of the survey are shown in spatial data in Appendix A3, showing the data as D-

values and a site substrate map and a summary is provided in Table 7.

River Sample D50 D84 x y

North Esk 1 39.58 111.71 333124 667599

North Esk 2 61.63 128 333170 667580

North Esk 3 55.96 122.15 333240 667593

North Esk 4 117.64 176.53 333285 667628

North Esk 5 59.71 118.5 333300 667805

North Esk 6 42.74 88.27 333258 667909

North Esk 7 40.89 65.86 333254 668002

North Esk 8 47.79 71.65 333369 668162

Table 7 - D-value for samples on the North Esk near Montagu Bridge Weir.


3.6 Ecological Survey

Ecologists were procured from Practecology to undertake an ecological assessment to inform

designs for improvements to fish passage and ease of sediment transfer at Montagu Bridge

Weir. This incorporated a desk based review of available data sources and a field survey. The

ecological field assessment was carried out in November 2015 and covered 250m upstream and

500m downstream of the weir and across a 100m wide riparian corridor centred on the mid

channel of the river. The findings of the ecological assessment are summarised in the sections

below and provided in full in the report Practecology (2015) Midlothian Esks Barrier Easement

Project – Phase 2a: Ecological Assessment of Montagu Bridge Weir in Appendix A2.

Protected habitats and species

Two statutory designated sites were identified, Dalkeith Oakwood SSSI which is immediately

adjacent to the downstream section of the survey area, and the Firth of Forth SPA, 5km

downstream of the weir. The weir modification within the river immediately downstream of

Montagu Bridge Weir is not considered to have any impact on statutory protected habitats.

Records obtained from online sources and The Wildlife Information Centre indicated the

presence of a number of protected and notable species within 1.5km of Montagu Bridge Weir.

However, the proposed weir easement will be limited in scale and likely to affect only those

habitats and species which occupy the river and its riparian corridor close to the works area.

The proposed works are unlikely to have significant impacts to habitats and species along the

River North Esk. Nevertheless, it will be necessary to remove trees and shrubs from the works

area and the route of access and it is recommended that this is undertaken ahead of the bird

breeding season to ensure nests do not delay works. It is also recommended that a tree close to

the proposed route of access should be retained and protected from both damage and

disturbance due to the potential for it to be used by bats. Although it is unlikely to be required,

should any retaining walls in the vicinity of the weir be affected by the works it is also

recommended that gaps and holes are blocked up to avoid nesting birds e.g. kingfisher utilising

this habitat. It would be necessary to confirm that any gaps in the retaining walls are not

occupied by roosting bats before they are blocked.

Invasive Species

There are a number of invasive non-native species of plant within the survey area, including

Himalayan balsam, Japanese knotweed, giant hogweed, cherry laurel and rhododendron. A

Construction Environmental Management Plan (CEMP) detailing biosecurity measures should

be provided by the main contractor and implemented during works to stop the spread of these

plants and contaminated soil.

Pollution Prevention

The CEMP should also cover what pollution prevention and control measures will be adopted

given the need for in-stream works. Avoiding the refuelling of plant on site, keeping all fuels in a

securely bunded area and having a spill kit on hand for the duration of works is also

recommended.


3.7 Initial Heritage Assessment and Consultation

Royal HaskoningDHV identified during Phase 1 of the project that consultation with Midlothian

Council and Historic Environment Scotland would be key to the successful implementation of

this project, due to the planning and heritage constraints. The development of the design in

consultation with Midlothian Council and Historic Environment Scotland is covered in Section

3.12.1 and Section 5 of this report.

The site is located within the grounds of Dalkeith Palace which is also within the ‘Dalkeith House

& Park Conservation Area’. The weir forms part of the Montagu Bridge (Grade A) Listing which

was identified as a significant project consideration and constraint. A Heritage Statement was

prepared to support the Planning Application and Listed Building Consent applications

necessary for the implementation of this project. This report is appended in Appendix E1.

The final design is considered to result in minimal alteration to the setting of Montagu Bridge

Weir as the existing contrast between the formal ‘romantic’ landscape setting upstream and the

‘wild’ landscape downstream will remain largely unaltered. The noise created by the water as it

flows over the weir will also remain unchanged which is considered an important aspect of the

heritage designation and ‘quality’ of the area. Although it is acknowledged that the construction

of the rock ramp and associated access will temporarily impact upon the tranquil and

picturesque setting of Montagu Bridge Weir, as well as the Garden and Design Landscape and

Conservation Area.

The use of boulders within the rock ramp to vary the flow of water and to create a resting pool is

considered to be in-keeping with the surrounding landscape downstream of the weir. It has been

recommended that a rock cladding is used along the retaining wall of the rock ramp as this is

considered to be more sympathetic to the designed ‘wild’ landscape downstream of the weir,

and will not misrepresent the original design of the listed building. The rock will create

additional habitat and may also facilitate the passage of eels.

In order to mitigate the impacts to Montagu Bridge and Weir, it is recommended that prior to

construction a condition survey of the listed building is undertaken. It is also recommended that

toolbox talks are conducted at the start of construction in order to highlight the location and

significance of the designated features, and exclusion zones are clearly demarcated around any

parts of the listed building which do not require works in order to prevent any accidental damage

during construction.

With respect to buried archaeology, which is at present unknown, it is recommended that an

archaeological watching brief is undertaken during the topsoil strip and a finds protocol is put in

place in the event that artefacts are recovered during the excavation of the river bed.

On completion of the works, the rock ramp will provide a range of flow depths and velocities to

account for a wide range of fish species that migrate up the River North Esk, whilst being


sympathetic to the designed ‘wild’ landscape setting which adds great value to the significance

of Montagu Bridge and Weir, and the surrounding designated landscape.

3.8 Early Contractor Involvement

We partnered with Lumsden and Carroll Civil Engineering (L&C) to provide early contractor

involvement (ECI) on this project. ECI gives a contractor’s view of the site and identifies access,

buildability and site restraints at an early stage.

L&C noted there was restricted access to the river, though access to the general area was good.

It was proposed to situate a compound in Steel Park, a grass field to the east of the river for

which a temporary haul road to the compound would be needed. A further access route would

then be put along an existing pedestrian access from the field down to the river (see Figure 18).

Figure 18 – Existing pedestrian access from the river to Steel Park.

L&C advised that the fish pass would be best built from the right bank, however it was noted by

our aquatic ecologist that the fish pass would be best built on the left bank where there were

preferential flows (attraction flows).

L&C input was used to develop an outline methodology for the CAR licence and undertook a

pricing exercise creating a bill of quantities for the proposed construction work, these are

appended in Appendix D2 (Note the contractor has provide commercial rates and this appendix

should be considered as Commercially Sensitive).



The first stage of the hydraulic modelling was to assess the site hydrology to determine river

flows at the weir. The gauge at Dalkeith Palace has been subject to vandalism over the years

and is not a reliable indicator of flood flows. The nearest flood gauge is at Dalmore, significantly

upstream of the study site and so can only be used as a rough guide to flood estimates.

The ReFH2 methodology was instead used to determine flood peaks and hydrographs for the

site. Catchment area was calculated as 133.89km2 and this area was checked manually in GIS.

As a check, the results were compared to the Dalmore gauge recommended by SEPA. These

flood flow estimates are tabulated in Table 8.

Return Period [y] Default ReFH2 [m3/s]

2 27.25

10 40.12

100 67.94

200 81.12

Table 8 - Flood flows for Montagu Weir.

However, to provide low flows for the analysis of fish pass, the gauge at Dalkeith Palace, close

to the study site is suitable. The gauged daily Q10%, Q50% and Q95% are tabulated in Table 9

and used for analysis of fish passage for the design at Montagu weir.

Daily Flow Dalkeith Palace Gauge [m3/s]

Q95% 0.577

Q50% 1.45

Q10% 4.67

Table 9 - Gauged daily flows at Dalkeith Palace.

After completion of the topographic survey, a 2D surface called a Digital Elevation Model (DEM)

of the existing weir and surrounding land was built in AutoCAD. The DEM was used to input into

a hydraulic model of the existing river. This provided a baseline to compare the weir removal

against, to see the impact of the changes. A report on the modelling can be found in Appendix

C1.

The design stage of the project required an iterative process with the hydraulic modellers to

ensure that the design details were added to the model, to calculate the effect on the river. A

crucial aspect of this design was in the sizing of the notch in the existing weir at the top of the

rock ramp. This would determine the flow into the rock ramp and thus the pass-ability of the

structure. Further information on the design development can be found in Section 5 of this

report.


The modelling work was undertaken by sub-consultants cbec eco engineering with Royal

HaskoningDHV’s principal hydraulic modeller providing expert reviews. The project

geomorphology expert worked with cbec during the geomorphology assessment. The modelling

data and reports can be found in Appendix C1.

The models produced included:

• A 1D hydraulic model of the existing conditions;

o 1D HEC-RAS model of existing condition North Esk at Montagu weir- this model

is used for design work and to act as a baseline for eventual sediment transport

and flood risk modelling;

• A 2D detailed model of the structure and design conditions;

o 2D (SRH-2D) low flow and bankfull flood model of North Esk at Montagu weir- this

model is used for design work;

• A 2D, mobile bed, sediment transport model using SRH-2D software.

o This model was used to consider if a sediment management plan could be put in

place at Montagu Bridge Weir. Further details are in Appendix I1 and Section 5

of this report.

3.10 Aquatic ecology

Royal HaskoningDHV appointed APEM to provide aquatic ecology support to the design

process. The aquatic ecologist visited the site and reviewed species data available from the

River Forth Fisheries Trust. APEM were involved in the iterative design process, advising on the

parameters for passage of different fish species under different flows. The aquatic ecologist

produced a technical design note that identifies the design criteria in relation to fish species and

supports the design evolution and this is provided in Appendix B1.

River Forth Fisheries Trust provided electrofishing data from various locations on the North Esk.

This identified that the main native migratory fish species present in the watercourse, and of

concern for fish passage, are:

• Atlantic salmon (Salmo salar);

• Sea and brown trout (Salmo trutta);

• Sea lamprey (Petromyzon marinus);

• River lamprey (Lampetra fluviatilis); and

• European eel (Anguilla anguilla).

3.11 Licences and Permits

3.11.1 CAR Licence Application

SEPA confirmed that Controlled Activities Regulations (CAR) authorisation is required for the

existing impoundment at Montagu Bridge Weir. The draft CAR licence application forms (Forms

A and D) have been provided in Appendix E2.


3.11.2 Planning Permission

A request for pre-planning advice was issued to Midlothian Council in October (21/10/2015) and

the following statement was provided by the Senior Planning Officer as part of the formal

response:

“Montagu Bridge was designed by the celebrated Scottish architect Robert Adam, and

completed by his brother James Adam following his death. For reasons of picturesque variety

Adam constructed small cauld, or weir, downstream. Water tumbles over the cauld and the

noise is amplified by the echo of the underside of the bridge; upstream the other side of the

bridge is reflected in the calm waters held back by the cauld. The noise and reflective qualities

of the water contribute to the setting of the bridge.”

It was confirmed by Midlothian Council that planning permission would be required for the

proposed works at Montagu Bridge Weir to create a fish pass at this location.

A meeting was held on site and in the Midlothian Council offices, with Historic Environment

Scotland and the Senior Planning Officer (Adam Thomson) from Midlothian Council on the 10th

December 2015. During the meeting the sketches for both the pre-barrage option and rock

ramp (see Appendix B3) were presented and the development process behind each design

was explained. The planning and heritage stakeholders consulted were broadly supportive of the

fish passage project and its aims. However, the pre-barrage option was not favoured due to the

following issues:

1. The pre-barrages would extend across the whole channel width and therefore the

existing weir will no longer be visible as it was intended to be viewed i.e. a cascading

waterfall.

2. The noise of the water passing over the existing weir, which is part of the setting, will be

altered due to the reduced head loss.

3. The pre-barrages, even if made to individually look natural with rock, will make very

man-made pools and will be regular in their layout.

4. The area downstream of the bridge is seen as a ‘wild designed landscape’ as opposed

to the more formal landscaped area upstream of the bridge. The pre-barrages would not

fit with these characteristics.

The rock ramp option was generally viewed more positively as:

1. The weir was not fully obscured by raised water level across the whole width of the

channel;

2. The noise from the weir will be similar to the existing situation; and

3. The rock ramp is less regular than the pre-barrages which is more befitting of the

‘designed wild landscape’ setting downstream of the bridge.

Further details on the decision to design a rock ramp instead of the originally preferred option of

a pre-barrage system have been provided in Section 5.


3.11.3 EIA Screening Request

Royal HaskoningDHV submitted an EIA Screening Request Letter (25/11/2015) to Midlothian

Council to confirm whether the proposed works will require a statutory Environmental Statement

to be prepared. Midlothian Council confirmed (02/12/2015) that the modification of Montagu

Bridge Weir will not require a statutory EIA. See Appendix E3 for the screening letter

responses.

3.11.4 Listed Building Consent

Listed Building Consent is the mechanism to ensure that any changes to listed buildings are

appropriate and sympathetic to their character. Listed Building Consent, specific to Montagu

Bridge, will be required for the proposed works to install a rock ramp to facilitate fish passage.


4 Dalkeith Weir Design

4.1 Design approach

The first phase of the Midlothian Esk project produced a feasibility and optioneering report

(Royal HaskoningDHV, 2015) that recommended the removal of Dalkeith Weir. The design work

undertaken in this second phase of the project developed the preferred option selected at the

feasibility stage into a detailed design fit for construction. It was confirmed with the River Forth

Fisheries Trust that the weir will be removed down to bed rock level, restoring the river to its

natural condition.

The aim of the work was to remove the weir, while not significantly increasing the flow depths,

velocities or bed shear upstream or downstream of the site which could destabilise the channel.

The design was undertaken to avoid any changes to the flow regime at the Newmills Road

bridge, situated downstream of the weir, as changes to the flow regime could cause potential

instability to the structure. Another key consideration during this phase was that as the weir is

located within a Conservation Area and the design was progressed to ensure the works were

sympathetic to its local character and setting.

A detailed topographic survey (see Appendix A1 and Appendix A6) was used to create long

sections and cross sections of the reach of the South Esk under the current conditions. A 2D

surface called a Digital Elevation Model (DEM) of the existing weir and surrounding land was

built from the data gathered during the topographic survey. The DEM was used as an input to

the hydraulic model of the river which assisted in the design development. This provided a

baseline to determine the impact of the weir removal. A report on the modelling that was

undertaken is located in Appendix C1.

An iterative design process was used to determine the design solution. The design team created

designs of the weir removal and river re-profiling and detailed them onto long sections and cross

sections. These were developed into a 2D hydraulic model. The design model outputs were

compared to the existing case model outputs to see the effects of removing the weir on average

water velocity, depth and bed shear.

The design aimed to move any increased velocities and bed stresses to areas where potential

bed erosion could be tolerated, and indeed used to improve the sediment supply through the

system, and to avoid the outside of the 90 degree bend in the river. The design went through a

range of iterations to develop the preferred channel alignment.

A sediment transport model was used as an additional tool to aid the prediction of erosion and

deposition within the river channel. Further information on the modelling process and findings

can be seen in Appendix C1 and the outline design drawings are provided in Appendix D1 and

final drawings are in Appendix F1.

During the development of the design, the ECI contractor priced the outline design drawings to

support the River Forth Fisheries Trust WEF application in January. The estimated costs from


the outline design stage can be found in Appendix D2, please note this appendix contains

materials that are commercially sensitive.

4.2 Final Design Hydraulic Model Results

The final design, seen in Appendix F1, was modelled using SRH-2D and the results of the

modelling are described below.

It is noted that the design aimed to reduce the immediate impact of weir removal as far as

possible, however, the river channel is a natural system, and the river will still continue to

develop with some natural erosion and deposition.

4.2.1 Hydraulic Modelling

This section describes the hydraulic modelling undertaken for the final design. Further detail on

the hydraulic modelling and sediment transport modelling can be found in Appendix C1.

The final design was run in a 2D hydraulic model to show the velocities, depth and bed shear.

The outputs from the model runs were displayed graphically. As expected, there is an increase

in both velocity and bed shear across the channel. The largest area of scour is on a steep

naturally occurring section of the river bed, upstream of the bend in the river. This means that

the higher stresses are away from the outside bend of the river, where the banks are also the

steepest. The shear stress areas are shown in Figure 17, and would lead to some localised

erosion. Elsewhere in the design the shear stresses are reasonable and not out of character for

the available sediments.


Figure 19 - Bed shears for the 2 year flow (for design).

It is important to compare the shear stresses between existing and design conditions. The

design increases stress in the section upstream of the weir as expected. The following figure,

Figure 19, compares the change in bed shear within the river channel Areas of blue indicate

where there is an increase in bed shear and so the potential (if high enough for erosion),

whereas red/yellow areas are reduced bed shear with the potential for accretion.


Figure 20 - Stress difference between design and existing conditions. Cold colours are excess design stress; Hot colours are excess

existing stress. The design increases stress upstream of the weir.

The figure shows that there is a general increase in bed shear upstream of the weir location,

which is to have been expected, with the highest increase to the shear stress upstream of the

bend in the river where the slope in the river bed appears to naturally steepen and which is now

exposed to shallow water flow whereas before it was submerged in the back water effects of the

weir.

4.2.2 Sediment Transport Modelling

A sediment transport hydraulic model was used to model the proposed design. This helped

improve the understanding of the implications of the design on the river system. Further details

on the specifics of the modelling can be seen in Appendix C1. This modelling was also used as

an aid during the design process.


The hydraulic modelling showed that the 2 year bank full flow presented a worst case for excess

shear in the steep sloped section upstream of the bend. The final design provides reasonable

stresses and velocities upstream of the weir: In the design area between the bend and the weir

the shear stresses peak at 120Pa on riffle crests, which would mobilize particles around 150mm

in diameter or less. However, there is a steep naturally occurring section of the design

immediately upstream of the bend. This area experiences significant shear stress (150-200Pa),

i.e. it would mobilise larger particles of up to 300mm in diameter.

The distribution of sediments is also calculated by the model and is not expected to change too

much: in the reach upstream of the weir the median particle diameter changes on average from

44mm to 41mm. Downstream of the weir there is limited deposition of sediment except in the

weir pool, and the reach d50 changes from 83mm to 70mm. Local to the largest area of erosion,

at the point of high shear, finer material (d50 20mm) is deposited on the inside of the bend and

the deepened pool is expected to have sediments of d50 60-70mm in it. It should be noted that

the weir will have collected finer material over time and so may not be representative of the

natural grading of the river bed, or what may be achieved in the future.

Results are presented for 12h and 24h into the 24h bankfull flow event to show a prediction of

how erosion and deposition of sediments may progress for the design condition with the weir

removed.

The effects of sediment transport and mobile bed materials were found to rapidly reduce the

shear stress hotspot in the steep area upstream of the bend by reducing the height of the riffle

crest upstream of the bend and reducing the slope of the steep section upstream of the bend.

The pool on the left bank downstream of the bend apex (colloquially known as Bowman’s pool)

was seen to deepen, with deposition of finer sediments on the inside of the bend.

The pool downstream of the current weir experiences deposition in the model also. Figure 21

and Figure 22 show predicted erosional and depositional areas during and after the 24h bankfull

event. Erosion is distinguished by ‘hot’ colours and deposition by ‘cold’ colours. The pattern is

broadly the same at 12h and 24h into the model run which indicates that the river rapidly

reaches a sediment equilibrium and that future events would have a much lesser impact on bed

levels. There is relatively little deposition of sediments downstream of the bridge.


Figure 21 Predicted erosion (hot) and deposition (cool) after 12h bankfull flow

Figure 22 Predicted erosion (hot) and deposition (cool) after 24h banfull flow.

The hydraulic modelling work summarised that the erosional effects of the removal of the weir,

replaced by the final design, are predicted to be limited to the riffle crest upstream of the river

bend, and a deepening of Bowman’s pool on the bend. Deposition occurs mainly in the old weir


pool (which we have planned to fill with material from upstream), but also continues downstream

slightly, and in reality beyond the downstream end of the model. The model assumes an infinite

depth of sediment and as such there is no limit to erosion. In reality in the region of Bowman’s

Pool, bedrock will rapidly be reached which will limit the depth of erosion in this location.

The design has used hydraulic modelling and sediment transport modelling to show that the

removal of the weir and the designed river bed does not cause an undue risk of channel

instability or risk to other structures on the river.

4.2.3 Flood Risk

The South Esk floodplain is generally constrained, with high tops of banks, and little flood

storage, other than the flat garden area on the right, upstream of the weir. 1D modelling is

relatively well suited to represent the site because of the small amounts of flood storage in the

area. 1D models produce depth and cross section averaged hydraulic variables: water level,

energy grade 2 , velocity magnitude and bed shear stress. Further details of the flood risk

modelling are available in Appendix C1.

To determine changes to flood risk, the 1D model was run for the 2, 10, 200 and 200+ climate

change year events (which is the 200 year event plus 20% discharge). Both water level and

energy grade were compared for existing and design conditions for each flow. For all cases the

flood levels and energy grades for the design were lower than those for the existing conditions.

The design therefore does not increase flood risk. Flood risk maps are included with the

modelling reports in Appendix C1, with the 200 year flood event outline shown in the Figure 23

below.

2 Energy grade is water level plus the level that it would increase by should the flow come to rest.


Figure 23 - 1 in 200 year flood map derived from 1D model levels and GIS. Design inundation is lower upstream of the weir.


4.3 Final Design

4.3.1 Downstream channel wall

Data obtained from the walkovers and surveys showed that the wall which forms the

downstream sides of the weir and the section immediately downstream adjacent to the scour

pool is in a poor state of repair. It has been noted in Section 4.1 that the weir removal has been

designed to avoid changes to the flow regime downstream of the weir. However, any weir

removal works undertaken will require consideration of how the adjacent weir wing

walls/retaining walls impact on the stability of the bank when the weir is removed and as such

may need to be repaired (see Figure 244 and Figure 255).

The channel walls immediately downstream (within 10m of the weir) and adjacent to the weir act

to retain the river bank and the slope above. These walls are tied into the existing weir structure

and may be structurally integral to the weir. Removal of the weir may adversely affect these

walls causing them to degrade further and compromise the stability of the river bank and upper

slope. As a minimum the walls should be repointed and repaired, and the relationship with the

weir structure investigated at the time of the weir removal (as described in Section 4.3.3)

It should be noted that the walls of Newmills Road bridge and just downstream will not be

repaired as part of this scheme because the modelling shows that these will not be affected by

any flow regime change (see Figure 2626). It is therefore the responsibility of the riparian owner

to maintain and repair these walls.

Figure 24 - Photo looking upstream towards Dalkeith Weir. Note the open joints and missing blockwork on the wall on the right hand

side. This wall ties into the existing weir in the centre of the picture.


Figure 25 - Photo looking towards Dalkeith Weir from the right bank. Note the far bank wall clad in vegetation (left bank) ties into the

existing weir.

Figure 26 - Photo looking at the downstream left-hand bank, downstream of road bridge, note the gaps in the existing bank retaining

wall. This wall is outside of the scope of works but is noted as already damaged prior to work commencing.


4.3.2 Upstream Channel

The upstream channel has been designed to be re-profiled for a 200m length upstream of

Dalkeith Weir. The sides of the river banks will be re-profiled to match the adjacent river bank

gradients, which are between 1 in 1 and 1 in 2, together with deepening of the watercourse in

places.

The re-profiling of the river channel will require removal of material from site. It was discussed

with the Trust that there is potential for efficiency if the material could be used on another

construction site, such as Montagu Bridge Weir. This would require a waste permit or exemption.

Some of the material that will be removed would have been transported downstream if it had not

been impounded by the weir. This has led to sediment starvation of the downstream catchment.

The re-use of some of the excavated material elsewhere in the downstream catchment for

channel nourishment is a potential, but would need careful consideration as the size of material

excavated may not match with the requirements in lower reaches. This additional sediment

would create additional habitat downstream for spawning fish, however a plan is needed to use

this in controlled releases.

There is an expectation within the design approach that some sediment movement will occur

following the schemes completion as the channel fully develops over time. This will release

material in to the system at a faster rate to start with and will help in addressing the long term

sediment starvation, but using natural processes to transport the material rather than man made

means.

The design drawing includes setting out points for a contractor to re-profile the river based on

the design. It is noted that no works will be undertaken to the left bank around the bend in the

river, where the banks are very steep and comprised of exposed rock.

4.3.3 Weir Removal

The works involve the removal of Dalkeith Weir. The weir removal will be one of the most

complicated parts of the construction works.

Due to the highly constricted access at the site, the steep banks, deep scour hole at downstream

of the weir and protected trees on the bank, it was not considered feasible to mobilise an

intrusive survey of the weir or trial holes on the adjacent river bank. The most effective way of

doing this will be during the construction stage, when Conservation Area consent is in place and

tree removal has been approved by Midlothian Council. This will allow access to the river bank

and the weir for construction plant. This has led to assumptions been made during the design

phase. As stated in Section 2.4, historic borehole logs were used to provide limited ground

information for the design.

The design requires the removal of the weir, which will create a 3m height difference between

the new river bed level and adjacent river banks. Downstream the banks have been supported


by vertical retaining walls. Slackening of the bank at the weir is not feasible as it would

undermine the existing walls downstream and potentially extend the scale of works downstream

towards Newmills Road Bridge. Our approach has been to remove the majority of the weir in a

trapezoidal cut, which will create a 12m wide river opening at the weir location and to use the

remaining weir sections to act as a retaining wall for the banks. The remaining sections of the

weir will be grouted to form a mass concrete wall and will be faced with recycled blockstone from

the existing weir face, to keep in character with the local area and protect it from future erosion.

In addition ground anchors will be required to connect the concrete block back to the existing

ground to resist the potential for the walls to slide into the channel which could lead to the slope

above slipping.

When the contractor starts work on site they are required to perform some initial investigation to

ascertain the composition of the weir and the surrounding banks, together with a structural

condition survey of the original weir, wing walls and any weir fill material. As the weir is

demolished, records to show the constitution of the weir and depth of any encountered bed rock

must be taken by the contractor. As early as possible during the construction, but after the

results of the investigations, the contractor must consult with the client and the client’s designer

to confirm the design approach and to agree if any changes in the design are required.

4.3.4 Construction Approach

The construction approach is estimated to take 8 weeks and will require working in lower flow

conditions to make the work safer. The River Forth Fisheries Trust have stipulated that

construction works should be carried out between May and August to avoid the sensitive periods

for native migratory fish species. A construction methodology was outlined in the supporting

information with the Controlled Activities Regulations (CAR) licence and can be found in

Appendix E2. This methodology was developed in conjunction with our ECI contractor to

provide a realistic programme and construction approach that minimises the risks to the South

Esk and surrounding habitats.

As mentioned in the section above the contractor will have to liaise with the client regarding the

findings from their own investigation works on weir once the construction phase begins. This

information will help the contractor form there demolition plan for the weir and have the potential

to reduce the need for the ground anchors.

4.3.5 Finishes and reinstatement

The design was undertaken with an aim to minimise the vegetation loss at the site. To remove

any trees within the Conservation Area requires a request to Midlothian Council. The Council

has the option to place a Tree Preservation Order on any of the trees due to their presence

within the Conservation Area.

Prior to the Planning Application / Conservation Area Consent Applications being submitted, a

tree survey must be completed. Following the tree survey the information will need to be

considered in conjunction with the design and drawings updated to reflect what trees will be

affected by the proposals. The drawings will indicate what trees will not be affected, those that


will be felled and those that require protection during the works. This information will be

presented in a format appropriate for submission with the planning application.

Any tree loss should be replaced with new tree planting of similar species and where possible

size Grass removed during the construction phase should be re-seeded within the first growing

season.

4.4 Summary of Option

• The weir will be removed down to bedrock to provide a shallower gradient across the

weir site. The ends of the weir will be left in place and faced with existing weir stone to

become the river bank retaining wall.

• The river will be re-profiled for 200m upstream of the weir.

• The channel walls immediately downstream of the weir are integral to the weir will be

repaired..

• The lade will remain intact but will be above the normal water level so that river water

cannot enter unless under very high flows.

4.5 Key Risks

• There is a risk that the landowner adjacent to Dalkeith Weir objects to the proposed

works as the only access to the site will be shared with the Old Mill House.

• There is a risk that local councillors or community groups are opposed to the works

within the Conservation Area and it is advised that consultation with the landowner and

other key stakeholders is carried out prior to the works.

• Due to the difficulty and cost of undertaking investigations on the weir during the design

stage there is limited information on the weir composition.

• Historic boreholes logs were used to show the retaining wall will need ground anchors.

• The Contractor must work with the client to consider if the design is appropriate once the

weir has been exposed. The ground conditions and composition of the weir should be

recorded during the demolition.

• There is a risk that the works do not receive approval from SEPA under the Controlled

Activities Regulations.

• There is a risk that the works do not receive Conservation Area Consent from Midlothian

Council.

• Midlothian Council could decide that Planning Permission is necessary for the proposed

works.

• Trees that need to be removed to undertake the works could be given Tree Preservation

Orders due to their location within the Conservation Area.

• High river flows could delay construction works on site and cause additional costs.

• An otter licence may be required for disturbance to the holt located downstream of the

weir.


5 Montagu Bridge Weir Design

5.1 Option Refinement

Following the Phase 1 work (see Section 1.2) on the Midlothian Esks the project team started

work on designing a pre-barrage structure downstream of Montagu Bridge weir. The detail of the

initial design work is presented in Appendix B2 in the Montagu Bridge Weir design note and

drawings, and a brief summary is provided below.

The findings of the topography surveys, combined with design recommendations from the

ecological survey (see Section 3 and Appendices A1 and A2) were used to inform the initial

design. A pre-barrage design based on 0.3m hydraulic head between pre-barrages was

created. The Figure 27 below shows the indicative layout of the pre-barrages.

Figure 27 - Pre-barrage arrangement (extract from Appendix B2).


On review of this initial design work a number of additional practical constraints were identified.

These constraints included the views of Midlothian Council and Historic Environment Scotland in

terms of the impact on the historic environment, ecological risks associated with the potential for

nesting birds and roosting bats in the right hand retaining wall and greater construction costs

than estimated during the feasibility phase of works due to the steeper gradient and wider

channel. Further detail on these constraints and the reasoning behind altering the design can be

seen in Appendix B2 in the Montagu Bridge Weir design note.

The alternative considered to the pre-barrages was a rock ramp. This rock ramp option was

preferred for the following reasons:

1. It can provide a range of flow depths and velocities to account for all native migratory

fish species; and

2. It provides a more natural bed slope, takes up less of the channel and leaves a

significant portion of the existing weir in existing condition.

3. It does not require work near the right hand bank wall where there is a high potential for

bird nesting and bat roosting.

4. It requires less intrusive construction work, as work would only take place on one side of

the river.

5. The retaining wall would be smaller in size than the pre-barrages, therefore potentially

reducing the construction costs and the construction programme.

6. The rock ramp was confirmed as the preferred option by Historic Environment Scotland

and Midlothian Council who are key project stakeholders.

This design change received approval from the River Forth Fisheries Trust in January 2016.


Figure 28 – Rock Ramp arrangement at Outline Design Stage (extract from Appendix B2).


Figure 29 - Example rock ramp from FAO, Fish Passes, Design, Dimensions and Monitoring

There were some outstanding design issues to be resolved with the rock ramp:

1. Managing sufficient attraction flow away from the weir to encourage native migratory fish

species to access the rock ramp.

2. Works to the existing weir in order to control the flow into the rock ramp i.e. cutting a

notch into the weir.

3. Future monitoring of the ramp’s performance over a range of flows to check its

effectiveness for passage of fish.

5.2 Design Approach

Following the design change the project team commenced work on the rock ramp design. The

design was informed by an aquatic ecologist design note (Appendix B1) which set the fisheries

criteria required for the design. A summary of all of the criteria can be found in Section 2 of this

report.

The topographic survey was used to create long sections and cross sections of the study area,

which in turn were used to create 1D and 2D hydraulic models, to provide river flows, depths and

velocities within the study area.

The fish pass design was developed in conjunction with the criteria set by the aquatic ecologist

and the design was then added to the hydraulic model. The modelled flows in the rock ramp

were assessed against fish species data to make sure the ramp was passable to a range of

species at a range of flows.


In addition during the development of the design, the ECI contractor priced the outline design

drawings to support the River Forth Fisheries Trust WEF application in January. The estimated

costs from the outline design stage can be found in Appendix D2.

The following sub-sections describe the detailed requirements of the design.

5.2.1 Operational Window

To provide the correct conditions for migration the ramp needs to provide different ranges of flow

and depth for different species at different periods in the year. In the absence of specific fish

migration data, the Environment Agency Fish Pass Manual (Armstrong et al, 2010) recommends

that a fish pass facility for upstream migration should be designed to operate across a flow range

from Q90 to Q10 for salmon, Q95 to Q10 for sea and brown trout and Q99 to Q70 for eel. There

is limited literature on Lamprey passage, however the EA Fish Pass Manual indicates sea

lamprey require passage at Q50 to Q20 and river lamprey low flows to Q30.

The operational flow window should therefore ideally be between Q99 and Q103. The figure

below gives a visualisation of the required operational window.

Figure 30 - Fish passage requirements for various species at a range if daily flows.

3 i.e. between the flow that occurs 99% of the time (a low flow) and one which occurs only 10% of the time (a higher flow).

Salmonids Trout Lamprey Eel

Q10%

Q20%

Q30%

Q40%

Q50%

Q60%

Q70%

Q80%

Q90%

Q95%

Required

Not Required

Daily Flow

Species

Required Passability


5.2.2 Hydraulic Criteria

The APEM Design note in Appendix B1 provides fish passage criteria and the table below

highlights the key criteria.

Species Max velocity (m/s) Minimum Depth (m)

Atlantic Salmon 2 0.15

Sea Trout 2 0.15

Brown Trout 2 0.1

Lamprey Species 0.5 0.08

European Eel 0.3 0.05

Figure 31 - Summary of hydraulic criteria from the APEM Design Note (Appendix B1).

5.2.3 Rock Ramp

The rock ramp was designed using the EA Fish Pass Manual (2010) and the United Nations

Food and Agricultural Organisation 2002 guidance for Fish passage (FAO, 2002), Fish Passes –

Design, dimensioning and monitoring. The EA Fish Pass Manual (2010) provided good detail on

fish pass selection and pass-ability criteria, the FAO (2002) provided specific detail about rock

ramp construction. Throughout this design phase APEM provided aquatic ecology design

support for the design of the rock ramp.

The preferred rock ramp gradient is 1 vertical in 20 horizontal.

The rock ramp maximum width could be effectively the width of the channel. However, in this

case there is a need for the existing weir to remain visible (due to heritage requirements) and for

water to pass over the weir and rock ramp simultaneously. The recommended minimum width is

2m (FAO, 2002).

Section 4 of the FAO 2002, contains information on ‘Close to Nature’ fish passes. The approach

is to use a rock ramp consisting of boulder sills perpendicular to the channel with perturbation

boulders between the sills. The boulders are aligned to slow water flow and increase depth,

however in-between each row of boulders there is a gap of least 0.4m to provide a path for all

species


Figure 32 - FAO 2002, Figure 4.20, boulder sills to break up flow in channels

.

Consideration was given to eel passage through the rock ramp, the design note produced by

aquatic ecologist, APEM, provided the following comments (full report available in Appendix

B1):

Eels are capable of locomotion both in water and on land using undulations of the body axis

(Ellerby et al., 2001), and therefore can pass very shallow features that may be impassable to

other fish species including salmonids, providing there is a suitable roughened substrate through

which they could crawl. Given that a rock ramp has a roughened bed substrate by design, such

a solution should be suitable throughout the range of flows required. In comparison to eels,

migratory river and sea lamprey do not seem to demonstrate the ability to move over land, and

there is no evidence that they can climb during their upstream migration (Russon et al., 2011;

Reinhardt et al., 2009). Notwithstanding, if suitable substrate is provided for them to crawl

through, such as that present in a rock ramp, upstream passage success of lamprey is likely to

be increased (Tummers et al., 2016), although potentially to a lesser extent than eel (Kerr et al.,

2015).

5.2.4 Resting Pool

For rock ramps longer than 30m, it is recommended that the pass has a gentle slope and deep

resting pools (FAO, 2002) to maximise its passability.

The Environment Agency Fish Pass Manual (2010), page 156, also recommends resting pools

for rock ramps that exceed a 2m head difference.

If a resting pool is used it should be a minimum of 1m deep for salmonids and a minimum length

of 3m. These design criteria have been taken into account during the design phase to maximise

the effectiveness of the rock ramp fish pass at Montagu Bridge weir.



5.3.1 Hydraulic Performance

The 2D hydraulic modelling undertaken by cbec eco engineering demonstrates that the rock

ramp fish pass is likely to function as a fish passable structure, with velocities in the pass largely

lower than 1m/s and water depths greater than 0.1m for flows between the Q95% and Q10%

daily flows. The full modelling report is available in Appendix C1.

The figure below shows the Q10% daily flow for the fish pass and existing river bed and

indicates a consistent water level within the fish pass of between 0.2m and 0.25m. This provides

greater than the minimum depth of 0.15m for salmonids recommend in the APEM design report

(Appendix B1).

Figure 33 - Comparison of existing impassable condition and passable condition down rock ramp at Q10% daily flow.

The modelling also produced results for Q10%, Q50% and Q95% - Figures 33, 34 and 35.

Further detail is available in the modelling report in Appendix C1.


Figure 34 - Depth along rock ramp fish pass at Q95% to Q10%. Resting pool is in the middle of the ramp at around 35-40m, the

downstream end of the ramp is around chainage 68m. (Full image in the Hydraulic Modelling report in Appendix C1).


Figure 35 - Velocity magnitude along rock ramp fish pass at Q95% to Q10%. R Resting pool is in the middle of the ramp at around

35-40m, the downstream end of the ramp is around chainage 68m. (Full image in the Hydraulic Modelling report in Appendix C1).

Figure 366 compares the ideal matrix of flow frequency passability for each species with the

results obtained from the modelling. For the majority of species the water depths and velocities

at the required flow frequencies provide passable conditions.


The notable exceptions are for salmonids and trout in the lower (more frequent) flows (Q60%

and below). This could be improved by increasing the depth of the notch in the weir and

narrowing the fish pass channel. However, creating a deeper notch in the weir would reduce the

water spilling over the rest of the weir, and at times there would be no flow over the weir crest.

The project team believed this would not be acceptable to the weir owner or meet heritage

requirements. Narrowing the fish pass width, would create deeper flows at low daily flows,

however this would increase the velocities at high daily flows to a point potentially too high for

lamprey passage and possibly too high even for trout and salmonids. The design has been

aimed at providing fish passage to salmonids and trout during higher flows, when migration runs

are more likely to occur.

Figure 36 - Summary of desired passability from the APEM report and achieved passability based on the hydraulic modelling.

5.3.2 Flood Risk

The 1D HEC-RAS hydraulic modelling showed that for all the design conditions in the main

channel the resulting water levels and energy grades were lower than the existing conditions.

The notch in the existing weir causes a slight reduction in water levels over the weir crest but

does not appear to increase levels downstream. It can be concluded that the design does not

increase flood risk. Further details are available in the modelling report found in Appendix C1,

including long sections comparing water depth along the model chainage. The 200 year flood

outline is shown in Figure 377.

Salmonids Trout Lamprey Eel Salmonids Trout Lamprey Eel

Q10% Q10%

Q20% Q20%

Q30% Q30%

Q40% Q40%

Q50% Q50%

Q60% Q60%

Q70% Q70%

Q80% Q80%

Q90% Q90%

Q95% Q95%

Required Achieved

Not Required Not Achieved

Not Required

Achieved Passability

Daily Flow

Species

Daily Flow

Species

Required Passability


Figure 37 - 200 year flood map. Existing conditions lower layer, design conditions upper layer. For no point is design condition

greater in extent than existing.


5.4 Final Design

5.4.1 Rock Ramp

A rock ramp along the left bank was designed to account for the 2m head drop of the weir. The

end of the rock ramp ties into the existing river bed, and as a result the rock ramp is 65m in

length.

To improve the chances of successful negotiation of the ramp a resting pool has been

introduced into the ramp.

The rock ramp was designed with the following parameters:

• The weir crest is 28mAOD;

• The downstream channel level is 25mAOD;

• The gradient of the rock ramp is 1 in 20;

• The rock ramp is 65m long;

• A resting pool is positioned at the half way along the rock ramp;

• The resting pool is 3m wide, 3m long and 1.2m deep;

• Boulder sills run parallel to the river flow; and

• Perturbation boulders are used between boulder sills to break up the flow.

5.4.2 Resting Pool

Royal HaskoningDHV have been made aware that poaching of fish within this reach of the North

Esk is a potential risk.

In the current situation fish migrating upstream reach the scour pool downstream of the weir and

attempt to pass the weir. The fish collect in the pool as they are unable to pass the barrier and

are at risk of poaching during this time.

With the rock ramp in place, the passability of the weir is greatly increased, but there remains a

risk that migrating fish will be poached as they navigate through the rock ramp and resting pool.

It is considered that with the rock ramp in place the passage of fish upstream will be an

improvement to the current situation, albeit some risk of poaching remains.

The resting pool within the rock ramp is required to maximise its effectiveness and the following

were considered during the design process:

• The rock ramp is designed on the left bank of the river furthest from the access paths

increasing the difficulty of getting to the site.

• Although a grating or mesh could be used to cover the fish pass/resting pool to reduce

the risk of poaching, it was discounted due to the implications on both the appearance

(heritage impact) and maintenance (debris collection).

• A resting pool in the rock ramp is recommended by the literature to maximise the

efficiency of the fish pass and removing it would reduce this greatly.


Additional mitigation to minimise the impact of poaching on the number of fish migrating

upstream should be considered, such as the planting of thorny vegetation species along the left

hand bank to inhibit access to the resting pool. However this would make future maintenance

more difficult. The potential for planting should be discussed with the landowner.

The design of the resting pool also incorporates boulders and cobbles to provide features that

fish can use as shelter when they are within the resting pool.

5.4.3 Retaining Wall

The rock ramp is supported by a U-shaped concrete wall which varies between 0.5 and 3.5m

tall.

The ‘Concrete Specification’ has been provided in the specification document alongside the

construction drawings (Appendix F1).

The retaining wall extends around 1m onto the crest of the existing weir to control the flow of

water into the rock ramp and surround the notch (see below) to maintain the ramp’s passability.

This extended wall will not be physically attached to the weir so that it can be removed in the

future if required without damaging the underlying structure.

5.4.4 Notch in the Weir

The size of the notch in the existing weir has been designed to control the volume, depth and

velocity of water in the rock ramp. In order to notch the weir, permission is needed from Historic

Environment Scotland and Midlothian Council, as part of the Listed Building Consent. Initial

consultation, as part of the pre-planning advice, was that this approach was acceptable if the fish

pass could demonstrate that it fit with the character and setting of the site.

A stop log slot has been built into the fish pass notch, to allow for the potential future regulation

of flow. This recess will allow the placement of a stop log in low flow conditions to reduce the

volume of water going into the fish pass if required.

5.4.5 Downstream Channel Works

There was concern that directing flows from the rock ramp towards the left hand side of the river

could cause scour to the bank. The design incorporates placement of roughly 2 tonne boulders,

1-2 deep within the river bank to protect it from scour. The boulders will be positioned on the

curve of the river. Small cobbles can be used to infill between the larger boulders if required.

As recommended in the APEM design report, larger boulders will also be spread across the

width of the remaining channel at the outlet of the rock ramp. This will help break up the flow

from the rest of the river and encourage fish to enter the rock ramp. An analysis of boulder size

was undertaken to calculate the mass required to resist movement during high flows, these

boulders will be 3-5T.


5.4.6 Finishes and reinstatement

The finishes at the site were designed to be sympathetic with the ‘wild landscape’ downstream of

Montagu Bridge. Two options were discussed, that of a wall clad with blockwork from matching

stone as shown in Figure 388 or by a more rugged approach of boulder stone piled against the

retaining wall shown in Figure 399.

Figure 38 - Rock ramp cladding option using stone to match existing site.

The options were discussed as part of the pre-planning advice with Midlothian Council and

Historic Environment Scotland; however no preference was given at that stage but advice that

whichever option is chosen it should fit with the setting of the ‘wild designed landscape’

downstream of the weir. The project team have decided to use the boulder cladding. The

concrete walls of the rock ramp will be clad using boulders along the riverward edge to blend

with the gravel river and visible bed rock. The rock ramp itself contains boulders and gravels that

will also mimic the river channel.

Figure 39 - Rock ramp cladding option using boulders.

Any tree loss will be replaced with new tree planting. Grass removed will be re-seeded.


5.4.7 Safety Considerations

During the design stage considerations were given to health and safety of the site to members of

the public and those who might undertake future maintenance on the site.

The proposed ‘rock ramp’ solution creates a fish pass structure that has a diverse range of flows

and velocities, suitable for passage of many aquatic species. The proposed solution is designed

to have minimal maintenance therefore requirements to access the rock ramp in future are

minimised.

The site is located on the left bank of the river, and access to the fish pass is through a wooded

sloping bank. A post and rail timber fence adjacent to the fish pass has been included to restrict

free public access, together with the possibly of a safety ring and signage to further discourage

access to the site. It is acknowledged that this will require consultation with the landowners and

the planning authority to ensure that the safety of the site is ensured while maintaining the

heritage of the site.

Stop log for sealing off the pass have not been included due to issues relating to safe access

and manual handling of any stop logs.

It was considered that a structure such as this fish pass should not be constructed without

consideration of appropriate access for future works or maintenance. During the works a

temporary access track will be constructed down to the river from the right bank (opposite side to

the fish pass). The River Forth Fisheries Trust should discuss the possibility of keeping this as a

permanent track down to the river with the landowner, which would facilitate a safe access route

to bring people and plant to the site. Only a small amount of temporary works would then be

required to perform any possible maintenance operations in the future.

5.5 Sediment Management Plan

The issue of sediment transport downstream of Montagu Bridge Weir is considered an important

aspect in the development of a good ecological status for the North Esk. It is noted that it is not

possible to remove Montagu Bridge Weir due to its listed status. This causes an issue in trying to

achieve sediment movement past the weir. As part of this project, a sediment management plan

was developed to consider an approach to management sediment in the North Esk downstream

of Montagu Bridge Weir. The full Sediment Management Plan report is provided in Appendix I1.

The report provided an assessment of the role of the Montagu Bridge weir in the context of

sedimentary processes of the North Esk in its entirety, concluding that the current disruption to

sediment transport associated with the structure has only a limited impact on the sedimentary

regime of the river.

The report, therefore, suggests that sediment management measures at this site are not likely to

be cost-effective and will be unlikely to deliver substantial benefits to the morphological

dynamics and associated quality of in-channel habitats at this site and the river system

downstream.


5.6 Summary of Design

A rock ramp, of width 4m, will be built on the left bank of the North Esk from Montagu Bridge

weir for a 65m length downstream. The ramp will contain boulder sills and perturbation boulders

that will break up the flow creating a diverse range of flow depths and velocities that fish can use

to migrate upstream. Due to the length a resting pool will be built into the rock ramp. Scour

protection to the banks will be placed downstream from large boulders and a resting pool at the

toe of the ramp.

5.7 Key Assumptions

• The bedrock downstream of the weir is 32mAOD and excavation will be too 31.5mAOD.

• The existing river banks are stable.

• The Q95 river flow is 0.577m3/s.

• The Q10 river flow is 4.67m3/s.

5.8 Key Risks

• There is a risk that the landowner objects to the proposed works, despite their

engagement in the process to date.

• There is a risk that the works do not receive Planning Consent or Listed Building Consent

due to stakeholders being opposed to the works.

• There is a risk that the works do not receive approval from SEPA under the Controlled

Activities Regulations.

• There is a risk that planning conditions imposed by Midlothian Council require different

and potentially more expensive finishes than the cost estimate includes.

• High river flows could delay works on site and cause additional costs.


6 Information to support the contractor

Additional design information to support the contractor can be found in the Construction Design

and Management Regulations 2015 (CDM) hazard log, Specification and Pre-Construction

Information documents in Appendix F2 and Appendix G1.

The CDM hazard log provides a list of risks and decisions undertaken at the design stage that a

contractor should review during the construction stage.

The Specification is for the works at for both sites and contains additional information for the

contractor that was not appropriate to place on the construction drawings.

The pre-construction information is a document the client can provide to the contractor to

discharge one of their duties under the Construction Design and Management Regulations 2015.

The document provides all the information the client understands about the site and the

constraints to the contractor to help them plan and manage the construction phase of the

project.


7 Conclusion and Recommendations

7.1 Conclusion

7.1.1 Dalkeith Weir

At Dalkeith Weir, the removal of the weir has been designed and modelled by a team of

engineers, geomorphologists, ecologists and heritage consultants. The removal of this weir will

open up the river to sediment transport and facilitate the passage of migratory fish, meeting the

project objectives set out by the River Forth Fisheries Trust to reinstate natural processes. The

design drawings are appended to this report in Appendix F1.

In accompaniment of the design the following applications have been completed, as far as

possible. These consents must be in place prior to the commencement of any construction

works. These draft applications are found in the appendices within Appendix E.

• CAR Authorisation (4 month determination period); and

• Conservation Area Consent (2 month determination period).

7.1.2 Montagu Bridge Weir

At Montagu Bridge Weir, a solution to allow migratory fish to pass the barrier has been designed

and modelled by a team of engineers, geomorphologists, ecologists and heritage consultants. A

fish pass has been designed to allow the upstream migration of the range of native migratory

fish species present in the North Esk across a range of flows. The design was sympathetic to

the local character and setting of the site to allow fish migration without detracting from the listed

structure and its setting. The design drawings are in appended to this report in Appendix F1.

In accompaniment of the design the following applications have been completed, as far as

possible. These consents must be in place prior to the commencement of any construction

works. These draft applications are found in the appendices within Appendix E.

• Planning Application (2 months determination period);

• Listed Building Consent (2 months determination period);and

• CAR Authorisation (4 months determination period).

7.2 Recommended Next Steps

7.2.1 Licences and Permits

As stated in Sections 7.1.1 and 7.1.2 above, the required consents and licences must be in

place prior to works commencing. There are a number of outstanding issues to be resolved by

the River Forth Fisheries Trust before these applications can be submitted with regard to liability.

A note has been provided alongside the draft applications on the outstanding requriments.

It should also be noted that a tree survey must be completed, for both sites, to accompany these

consent applications. The tree survey will need to be processed to reflect what trees will be


affected by the proposals i.e. not affected, felled or require protection. This information will be

presented in a format appropriate for the Planning Application (Montagu Bridge

Weir)/Conservation Area Consent application (Dalkeith Weir). The work required will include the

survey, GIS time, engineer input and time to present to planning authority. Once this is

completed the applications can be submitted.

Once the planning application is submitted the River Forth Fisheries Trust will have to support

and answer any queries that occur from the planning process. It is also likely that planning

conditions will accompany the consent and will need to be discharged prior to the

commencement of work.

7.2.2 Vegetation Clearance

The construction works are proposed for summer working (May to September), to ensure that

the most sensitive periods for in-river working are avoided. It is recommended that prior to the

bird breeding period, specialist vegetation clearance is undertaken to remove potential bird

nesting habitat, which could prevent the construction works from occurring within that season.

This would be best done in the winter months prior to the construction. It is advisable to have an

ecologist on site during this vegetation clearance.

While vegetation management is being undertaken it is also advisable that the River Forth

Fisheries Trust consider the clearance of invasive species noted in the ecology survey. This

would reduce the risk of the spread of invasive species during the construction works.

7.2.3 Photographic Weir Surveys

It is expected that a photographic record of the weir structures before construction work will need

to be undertaken, and this is likely to be enforced as a condition for the Conservation Area

Consent (Dalkeith Weir) and potentially a Planning condition/Listed Building Consent condition

(Montagu Bridge Weir). These surveys will need to be undertaken by a heritage specialist.

7.2.4 Appointing a Contractor

The River Forth Fisheries Trust will need to appoint a contractor to undertake the works. The

Trust will need to decide on the type of contract for the work and prepare tender documents. The

Trust will need to issue the tender to interested contractor and give a period of 6-8 weeks to

tender for the works. During this time the Trust will have to answer questions on the tender from

the bidding contractors. It is recommended that the trust take the tendering contractors to the

site to undertake a site walkover to familiarise themselves with the site and the access

constraints.

While the contract documents are being developed it is advisable that the River Forth Fisheries

Trust update the Pre-Construction Information document, produced as part of the design stage,

with any latest developments, for example planning conditions or landowner constraints.

This process of appointing a contractor could take 3-4 months, so it is recommended that the

compilation of tender documents starts in January/February of the year the construction will

occur so that the contractor is appointed in time to start construction in the summer months.


7.2.5 Construction Stage

Royal HaskoningDHV recommend that the work is undertaken in the summer months to avoid

sensitive periods for in-river working and also have a greater potential of lower river flows. At

both sites the construction period is estimated to be 8 weeks in duration. Starting at the end of

May or beginning of June would be preferred. If any delays were to occur to the programme,

there would still be summer working allowed in August.

The Trust should consider the Construction, Design and Management Regulations 2015 (CDM

2015) in the work they are doing, the Trust will undertake the CDM role of a Client. Information is

available from the Health and Safety Executives website on the duties of all parties involved in

construction projects.

The HSE website states that Client duties include:

Make suitable arrangements for managing a project, including making sure:

• other duty-holders are appointed as appropriate;

• sufficient time and resources are allocated.

Make sure:

• relevant information is prepared and provided to other duty holders;

• the principal designer and principal contractor carry out their duties; and

• welfare facilities are provided.

7.2.6 Future Monitoring of Montagu Bridge Weir Fish Pass

Fish pass guidance recommends future monitoring of rock ramps to assess their passability and

provide evidence if adjustments to the boulder positions are needed. We have consulted with

APEM, our aquatic ecologist, to develop a price for monitoring the rock ramp over a period of

high and low flows for one year. Ideally this will be to monitor for 2 months (1 month in summer

and another month in winter). In additional a visual inspection of the pass under a range of flows

could be undertaken to determine where flows may be too high, or depths too shallow,

throughout the pass, and thus where adaptations may be required. We have provided cost

estimates for a consultant to undertake the work, but note that the Trust may be able to

undertake the work themselves at considerably reduced cost. We recommend that this would be

undertaken in the year after construction.

Following the monitoring, the rock ramp may need amendments to the boulder positions to alter

the flows if it is believed the flow regime is sub-optimal for fish migration during some flow

conditions. This item should be considered a risk item as it may not be needed. However,

current literature suggests that it is prudent to plan for minor modifications. It is noted that this is

not a change to the fish pass super-structure and would likely consist of the following

construction activities:

• Re-position of boulders.

• Placing additional boulders.

• Changing the size of the weir notch.

A cost estimate for this is provided in Appendix D2.

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Appendix A – Site Investigation Data

Appendix A contains the following information, split into information about each weir:

A1 – Topographic survey

A2 – Ecology Survey

A3 – Sediment Sampling

A4 – Geophysical Survey

A5 – Historic Borehole logs

A6 – Sections and utilities

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Appendix B – Desgin Technical Notes

Appendix B contains the following:

B1 – APEM Design Note

B2 – Montagu Bridge Weir Design Note

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Appendix C – Hydrualic Modelling

Appendix C contains the following:

C1 – Hydraulic Modelling

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Appendix D – Outline Design

Appendix D contains the following:

D1 – Outline Design

D2 – Cost Estimate

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Appendix E – Licences and Permits

Appendix E contains the following:

E1 – Heritage Report

E2 – Draft CAR Licence Applications

E3 – Draft Planning Application (Montagu Bridge Weir)

E4 – Visualisations

E5 – Draft Listed Building Consent (Montagu Bridge Weir)

E6 – Draft Conservation Area Consent (Dalkeith Weir)

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Appendix F – Construction Drawings

Appendix F contains the following:

F1 - Construction Drawings

F2 - CDM Hazard Log

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Appendix G – Pre-construction information


G1 - Pre-construction information

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Appendix H – CDM 2015 Letters


H1 – CDM 2015 Appointment Letters

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Appendix I – Sediment Manegment Plan

Appendix I contains the following:

I1 – Sediment Management Plan

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Appendix J – Communications Log

Appendix J contains the following:

J1 – Communications Log

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