boston london road fishing quay · t iman001472 blrfq icsr 002 a...

$: Boston London Road Fishing Quay · T IMAN001472 BLRFQ ICSR 002 A P:\Cambridge\Demeter\EVT\Projects\339200 Boston Barrier TWAO\07 Reports\IMAN001472-002 London Rd Fishing Quay\01 04$
Boston London Road Fishing Quay

Inspection and Condition Survey Report

May 2016

Environment Agency

IMAN001472 BLRFQ ICSR 002 A

P:\Cambridge\Demeter\EVT\Projects\339200 Boston Barrier TWAO\07 Reports\IMAN001472-002 London Rd Fishing Quay\01

04 May 2016





May 2016

Environment Agency

Mott MacDonald, 22 Station Road, Cambridge CB1 2JD, United Kingdom

T +44 (0)1223 463500 F +44 (0)1223 461007 W www.mottmac.com

IMAN001472/BLRFQ/ICSR/002/A 04 May 2016 P:\Cambridge\Demeter\EVT\Projects\339200 Boston Barrier TWAO\07 Reports\IMAN001472-002 London Rd Fishing Quay\01 TEXT\IMAN001472-BLRFQ-ICSR-002 A_7 wf.docx

Boston London Road Fishing Quay Inspection and Condition Survey Report

Revision Date Originator Checker Approver Description

A May 2016 W Fan P Harvey M Taylor First Issue

Issue and revision record

Information class: Standard

This document is issued for the party which commissioned it and for specific purposes connected with the above-captioned project only. It should not be relied upon by any other party or used for any other purpose.

We accept no responsibility for the consequences of this document being relied upon by any other party, or being used for any other purpose, or containing any error or omission which is due to an error or omission in data supplied to us by other parties.

This document contains confidential information and proprietary intellectual property. It should not be shown to other parties without consent from us and from the party which commissioned it.



Chapter Title Page

Executive Summary i

1 Introduction 1

1.1 Scope of Report ____________________________________________________________________ 1 1.2 Description of Structure ______________________________________________________________ 1 1.3 Source of Information ________________________________________________________________ 4 1.4 Previous Inspection and Maintenance History _____________________________________________ 4

2 Condition Assessment 5

2.1 Condition Grades ___________________________________________________________________ 5 2.2 General Condition __________________________________________________________________ 5 2.3 Steel Sheet Piling ___________________________________________________________________ 8 2.4 Reinforced Concrete Capping Beam ___________________________________________________ 10 2.5 Wooden Fendering _________________________________________________________________ 12 2.6 Vegetated Quay Side _______________________________________________________________ 13 2.7 Non-vegetated Quay Side ___________________________________________________________ 15 2.8 Ladder Access ____________________________________________________________________ 16

3 Residual Life Assessment 19

3.1 Deterioration Curve ________________________________________________________________ 19 3.2 Residual Life Assessment ___________________________________________________________ 21

4 Conclusion and Recommendations 23

4.1 Conclusion _______________________________________________________________________ 23 4.2 Recommendations _________________________________________________________________ 23

Appendices 25

Appendix A. Condition Rating Drawing ____________________________________________________________ 26 Appendix B. As-built Drawings __________________________________________________________________ 27

Contents

i



Mott MacDonald has been commissioned by the Environment Agency (EA) to

complete an Inspection and Condition Survey Report of the EA owned section of

London Road Fishing Quay in Boston as part of Boston Barrier Project. A visual

inspection from the land was carried out on 18th Feb 2016 for the upper parts of

the structure that can be inspected without the need for special access equipment.

The condition grade is classified based on the Condition Assessment Manual,

CAM (Environment Agency 2006). The current Condition Grade of the steel sheet

pile structure based on this visual inspection was considered to be 3 (in Fair

Condition). Other parts of associated elements to the main sheet pile structure are

also in Fair Condition apart from the reinforced concrete capping beam, which is

considered to be in Fair to Poor Condition. The access ladder is sub-standard and

poses serious Health and Safety risks to users.

Based on the deterioration curves, the time for the asset to deteriorate from its

current Condition Grade (CG3) to Condition Grade 4, which is considered the

minimum Condition Grade acceptable for that structure, is 13 years.

The current load capacity of the quay cannot be determined due to the lack of as-

built information about the sheet pile.

Based on the findings from the condition assessment and residual life

assessment, it is recommended that:

� concrete repair to reinforced concrete capping beam shall be carried out,

� the voided hole in the pavement shall be investigated;

� the sub-standard ladder access shall be upgraded to meet the current

standards;

� vegetation clearance shall be carried out at the vegetated quay side; and

� resurfacing to pedestrian footway shall be carried out.

Executive Summary



1

1.1 Scope of Report

Mott MacDonald has been commissioned by the Environment Agency (EA) to complete an Inspection and

Condition Survey Report of the EA owned section of the London Road Fishing Quay in Boston as part of

Boston Barrier Project.

The purpose of this report is to inform the EA of the condition of its asset. The scope of report is as follows:

� Condition assessment of quay

� Residual life assessment

� Recommendations

A visual inspection from the land was carried out on 18th Feb 2016 for the upper parts of the structure that

can be inspected without the need for special access equipment. . The inspection was carried out at

9:30am when the tide was low with good weather conditions.

An assessment of the load capacity of the quay has not been undertaken as part of this assessment due to

a lack of data regarding the as-built design of the quay as well as the additional intrusive investigations that

would be required.

1.2 Description of Structure

The steel sheet pile retaining wall is located along the tidal reaches of the Witham Haven at London Road

west of the Port of Boston. The Ordnance Survey Grid Reference of the structure is 532653E/343173N. A

location plan is shown in Figure 1-1.

The structure was constructed circa 1950 according to the previous visual inspection drawing (see

Appendix A) and consists of an anchored steel sheet pile wall with concrete capping beam on top. The

quay is currently used by the local fishermen to dock their fishing boats and land any catch. The EA owned

section is approximately 200m long including a vegetated section and non-vegetated section. There is

dense grass growing in the vegetated section retained by the sheet pile wall. The non-vegetated section

retained by the sheet pile wall comprises an approximately 2.5m wide pedestrian footway and an

approximately 5.4m wide pavement area for loading purpose. There are numbers of ladder accesses to

boats at approximately 15m intervals. See Photo 1-1, Photo 1-2 and Photo 1-3 for fishing quay.

1 Introduction



2

Figure 1-1 Location Plan

Source: MM Ordnance Survey data: © Crown Copyright. All rights reserved. Licence number AL100019901

Photo 1-1 Boston London Road Fishing Quay (Vegetated Section - South facing)

London Road Fishing Quay

Port of Boston

Boston



3

Photo 1-2 Boston London Road Fishing Quay (Vegetated Section - North facing)

Photo 1-3 Boston London Road Fishing Quay (Non-vegetated Section - South facing)



4

1.3 Source of Information

The condition of the quay structure has been assessed in accordance with the following guidance:

� EA Condition Assessment Manual - Ref. 166_03_SD01

� Guidance on determining asset deterioration and the use of condition grade deterioration curves – Ref.

SCHO0509BQAT-E-P

There is limited as-built information available at the time of preparing this report. The as-built drawings

received so far are listed below and attached in the Appendix B:

Table 1-1 As-built drawings

Drawing Name Drawing Title

116/16 Details of piling, waling, ladder, capping beam and single tie anchor block

116/21A Section IOA – Mussel Stage

1.4 Previous Inspection and Maintenance History

A visual site inspection was undertaken in 2010 by Halcrow and Jacobs. Following this inspection the quay

structure was given an approximate overall condition grade of 3 (in Fair Condition). No record of this

inspection report was available at the time of this study. However, a drawing prepared by Halcrow and

Jacobs showing the condition rating is attached in Appendix A.

No maintenance records were available at the time of preparing this report.



5

2.1 Condition Grades

Condition grade deterioration curves offer a standardised approach to assess and quantify the

deterioration of flood defence assets.

Condition grades are based on the Condition Assessment Manual, CAM, (Environment Agency 2006)

definitions of condition grades per asset type (as described in text and illustrations in CAM). Five condition

grades as used, with their general descriptions given in Table 2-1.

Table 2-1 Condition grades

Grade Description of condition Extent of defects

1 Very good Cosmetic defects that will have no effect on performance

2 Good Minor defects that will not reduce overall performance of asset

3 Fair Defects that could reduce performance of asset

4 Poor Defects that would significantly reduce performance of asset

5 Very poor Severe defects resulting in complete performance failure

Source: Condition Assessment Manual, Environment Agency, 2006

2.2 General Condition

The current condition of the quay is fair with a condition grade of 3 based on the visual inspection. See

Photo 2-1 for London Road Fishing Quay.

It should be noted that access to the quay wall was limited as the access ladders down to the front of the

sheet piling were unsafe and access to the bottom of the ladders was restricted due to either fluvial flows

or the location of boats adjacent to the quay wall. Only one access ladder would give access to the mud

flats; however the uncertain footing on the flats led to the preference to avoid access down the ladders at

this time.

2 Condition Assessment



6

Photo 2-1 London Road Fishing Quay (South facing)

During the site visit measurement of the thickness of the piles was undertaken using an ultrasonic

thickness gauge allowing a reasonable assessment of pile thickness to be made along the quay wall.

However due to the access constrains outlined above no thickness measurements could be undertaken

safely in the lower section of the wall. As such this assessment is limited to measurements along the

underside of the piling capping beam. Table 2-2 re-produces the results of the pile thickness

measurements.

Table 2-2 Thickness measurement

Location Location Description Sheet Pile Thickness (mm)

Location 1 At 1st hand railing from North side 8.7

Location 2 At 3rd hand railing from North side 9.4

Location 3 At 6th hand railing from North side 9.8

Location 4 At 9th hand railing from North side 8.9

Location 5 At 1st access ladder from South side 9.4



7

Figure 2-1 Location for sheet pile thickness measurement



8

The variation between the results show above was considered to be within the tolerances of the

measurement method and therefore an average thickness of 9.2mm was considered as a reasonable

estimate of the current pile thickness along the quay wall in the areas measured.

An overall assessment of the piling thickness indicated that the steel thickness appeared adequate.

Furthermore no indication of structural failure or even deformation was apparent along the quay side wall.

However it should be noted that this assessment is made with no reference to as-built information (sheet

pile thickness information was not shown on the as-built drawings received), or dates of construction which

were unavailable at the time of this report.

Finally it should be noted that the areas of greatest concern in sheet pile retaining walls often relate to

those in the wetting-drying area which were inaccessible at the time of the visit. If such measurement were

required extended access to the quay wall would be necessary.

2.3 Steel Sheet Piling

The steel sheet pile wall is considered to be in Fair condition with a condition grade of 3.

The main findings for the steel sheet piling are listed below:

� Misalignment appears in a short section with dense vegetation covered concrete capping beam (see

Photo 2-2).

� Joints are generally in good condition (Z profile pile, section type is unknown).

� Minor corrosion in atmospheric zone.

� At some locations, anchor plates are missing (see Photo 2-3).

� Pile thicknesses appear reasonable with respect to modern pile design, although this may not relate to

the original pile design. However no areas of deformation or structural failure were apparent;

� Silt has built up locally at some areas.



9

Photo 2-2 Misalignment of sheet pile wall

Photo 2-3 Missing anchor plate

Missing anchor plate

Misalignment in the dense vegetation area



10

2.4 Reinforced Concrete Capping Beam

The reinforced concrete capping beam is in Fair to Poor condition with a condition grade of 4.

The main findings for the reinforced concrete capping beam are listed below:

� Significant concrete spalling with exposed reinforcement appear in some areas (see Photo 2-4 and

Photo 2-5).

� Cracks appear in some areas (see Photo 2-6).

� The alignment and level of the concrete capping beam appears to show no significant signs of

movement (see Photo 2-7).

Photo 2-4 Concrete spalling

Severe concrete spalling with exposed reinforcement along bottom edge of the capping beam



11

Photo 2-5 Reinforcement exposure

Photo 2-6 Concrete cracking

Severe concrete spalling with exposed reinforcement

Significant cracking in concrete



12

Photo 2-7 Alignment of concrete capping beam

2.5 Wooden Fendering

The wooden fendering is in Fair condition with a condition grade of 3.

The main findings for the wooden fendering are listed below:

� Some cracking were shown but generally well secured and showing only limited weathering (see Photo

2-8 & Photo 2-9).



13

Photo 2-8 Crack in wooden Fendering

Photo 2-9 Wooden Fendering

2.6 Vegetated Quay Side

The vegetated quay side is in Fair condition with a condition grade of 3.

The main findings for the vegetated quay side are listed below:

� Existing ground was covered with dense grass and was difficult to inspect, however no significant

deviation in ground profile were apparent (see Photo 2-10).

� There are well established trees adjacent to the structure could potentially cause misalignment of the

piles (see Photo 2-11).



14

Photo 2-10 Vegetated quay side

Photo 2-11 Well stablished trees nearby

Tree is about 5m to sheet pile wall



15

2.7 Non-vegetated Quay Side

The non-vegetated quay side is in Fair condition with a condition grade of 3.

The main findings for the non-vegetated quay side are listed below:

� The alignment of the pile is generally satisfactory.

� Some areas of local subsidence of ground indicate possible voiding. No obvious sign of pile movement

at locations, probably ground movements behind wall (see Photo 2-12).

� Pavement is in fair condition showing cracking and uneven ground (see Photo 2-13).

Photo 2-12 Local subsidence of ground

Possible void behind the sheet pile wall



16

Photo 2-13 Pavement

2.8 Ladder Access

The ladder is in Fair condition with a condition grade of 3.

The main findings for the ladder are listed below:

� Rungs are in reasonable condition (see Photo 2-14). However the ladder constitutes a significant

Health and Safety risk due to its constrained dimensions (see Figure 2-2) and does not meet principle

dimension requirements specified in the current standards (BS EN ISO 14122-4) for fixed ladders. We

would suggest that if this is an EA owned asset then this would constitute a significant liability. Due to

lack of the as-built record, the Contractor who installed the ladders previously is unknown.

� Hand railing at the top of the ladder is in good condition (see Photo 2-15).



17

Photo 2-14 Access ladder

Photo 2-15 Hand railing



18

Figure 2-2 Cross section view and plan view of ladder access



19

3.1 Deterioration Curve

Deterioration curve quantify the residual life of some type of assets and for different condition grades with

and without maintenance, allowing the user to evaluate their deterioration over time, see Table 3-1.

The ‘best estimate’ in the table assumes ‘standard’ conditions. If the loading on, or aggressiveness of

environmental conditions around, an asset is likely to be higher or lower than typical design condition, a

faster or slower rate of deterioration should be chosen depending on the severity of this shift.

3 Residual Life Assessment

20 IMAN001472/BLRFQ/ICSR/002/A 04 May 2016 P:\Cambridge\Demeter\EVT\Projects\339200 Boston Barrier TWAO\07 Reports\IMAN001472-002 London Rd Fishing Quay\01 TEXT\IMAN001472-BLRFQ-ICSR-002 A_7 wf.docx


Table 3-1 Deterioration times (years) to different condition grades for different asset types and exposures

Source: Guidance on determining asset deterioration and the use of condition grade deterioration curves



21

3.2 Residual Life Assessment

Step1: Identify the type of asset

Step 2: Identify the factors influencing the asset life

Step 3: Identify the appropriate deterioration curves

Three deterioration rates are extracted from Table 3-1 considering the options:

Table 3-2 Best estimate (m)

Type Grade 1

Very Good Grade 2 Good

Grade 3 Fair

Grade 4 Poor

Grade 5 Very Poor

Sheet Piles 0 8 30 43 50

Table 3-3 Fastest estimate (m)

Type Grade 1


Grade 3 Fair

Grade 4 Poor

Grade 5 Very Poor


Table 3-4 Slowest estimate (m)

Type Grade 1


Grade 3 Fair

Grade 4 Poor

Grade 5 Very Poor


Step 4: Determine the deterioration curve

The fastest estimate Table 3-3 is chosen as it is assumed that the asset is under aggressive coastal

environment and being used regularly by the fishermen.

Vertical wall Steel sheet pile wall

Coastal environment No maintenance in sheet piles

Vertical wall Steel Piles Coastal Both No



22

Step 5: Assess the current condition grade

The Condition Grade of the sheet pile structure is 3 (Fair)

Step 6: Forecast the expected deterioration time

The time for the asset to deteriorate from its current Condition Grade (CG3) to Condition Grade 4, which is

considered the minimum Condition Grade acceptable for that structure, is 13 years (25-12).



23

4.1 Conclusion

The current Condition Grade of the steel sheet pile structure based on this visual inspection is 3 (in Fair

Condition). Condition grade is classified based on the Condition Assessment Manual, CAM (Environment

Agency 2006). Other parts of associated elements to main sheet pile structure are also in Fair Condition

apart from the reinforced concrete capping beam, which is in Fair to Poor Condition. The access ladder is

sub-standard and poses serious Health and Safety risks to local users.

Based on the deterioration curves, the time for the asset to deteriorate from its current Condition Grade

(CG3) to Condition Grade 4, which is considered the minimum Condition Grade acceptable for that

structure, is 13 years.

Current load capacity of the quay cannot be determined due to lack of as-built information.

4.2 Recommendations

Based on the findings from condition assessment and residual life assessment, the recommendations are

listed in Table 4-1:

Table 4-1 Identification of Required Structural Works

Priority Structural Work Required Description Item Unit

Total budget Price

Timing requirement for investment Justification

1 Concrete repair Reinforcement exposed and concrete spalling in some areas

10 No. £50,000 Within next year

Extending asset life

2 Void investigation Possible void appears behind the sheet pile wall


Health & Safety

3 Ladder access upgrading

Current ladder access is sub-standard


Health & Safety/ Sub-standard structure

4 Vegetation clearance

In order to ensure effective inspection of the pile wall it is preferable to ensure vegetation clearance. However it is also recommended that the well-established trees remain in place. Although not ideal any removal could cause instability within the wall. Monitoring of

600m2 £2,500 Within next 5 years

Extending asset life

4 Conclusion and Recommendations



24

Priority Structural Work Required Description Item Unit

Total budget Price

Timing requirement for investment Justification

the wall should be undertaken to ensure no adverse effects and removal only undertaken where clear evidence of pile movement is seen

5 Pedestrian footway resurfacing

Cracking and local subsidence on pavement

250m2 £10,000 Within next 5 years

Extending asset life/Health & Safety



25

Appendices

Appendix A. Condition Rating Drawing ____________________________________________________________ 26 Appendix B. As-built Drawings __________________________________________________________________ 27



26

Drawing IMAN001472/001 is attached.

Appendix A. Condition Rating Drawing



27

As-built drawings listed below are attached.

� 116/16 – Details of piling, waling, ladder, capping beam and single tie anchor block

� 116/21A – Section IOA – Mussel Stage

Appendix B. As-built Drawings

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