Document Number: EOS 07-0118
Date: 24/03/2017
ENGINEERING OPERATING STANDARD
EOS 07-0118
REQUIREMENTS FOR THIRD PARTY WORKS IN THE VICINITY
OF UK POWER NETWORKS ASSETS
Network(s):
EPN, LPN, SPN
Summary:
This engineering operational standard details UK Power Networks requirements for
third party development works affecting UK Power Networks assets.
Author:
Uriel Arias
Date:
24/03/2017
Approver:
Paul Williams
Date:
21/04/2017
This document forms part of the Company’s Integrated Business System and its requirements are mandatory throughout UK
Power Networks. Departure from these requirements may only be taken with the written approval of the Director of Asset
Management. If you have any queries about this document please contact the author or owner of the current issue.
Applicable To
UK Power Networks
External
☒ Asset Management
☒
G81 Website
☐ Capital Programme
☒
UK Power Networks Services
☒ Connections
☐
Contractors
☐ Health & Safety
☒
ICPs/IDNOs
☐ Legal
☐
Meter Operators
☐ Network Operations
☐ Procurement
☐ Strategy & Regulation
☐ Technical Training
THIS IS AN UNCONTROLLED DOCUMENT, THE READER MUST CONFIRM ITS VALIDITY BEFORE USE
Version: 3.0
Requirements for Third Party Works in the Vicinity of UK
Power Networks Assets
Document Number: EOS 07-0118
Version: 3.0
Date: 24/03/2017
Revision Record
Version
3.0
Review Date
21/04/2022
Date
24/03/2017
Author
Uriel Arias
Why has the document been updated – Review to include greater detail of assessment criteria and
guidance
What has changed – Title changed and document layout reviewed; Section 4 added for general
considerations applicable to any works; Distinguishable sections for works around substations,
tunnels, cable bridges and underground Cables created and develop from project inception to
construction phase. Clarification on reasoning for 1/1000 differential maximum settlement criteria
introduced. BS and ISO references updated. Tunnels section revised to include location survey and
assessment criteria for tunnel’s condition. Other minor changes.
Version
2.0
Review Date
03/02/2019
Date
18/01/2016
Author
Helen Amare
Why has the document been updated – Periodic review, content of document updated following site
meetings and discussions with developers and details of ECS 07-1000 combined to this document.
ECS 07-1000 to be withdrawn.
What has changed – Sections 1 (Introduction) and 2 (Scope) updated, Section 4 (Details) updated;
guidance to developers regarding UKPN requirements for ventilation, replacement of plants and safety,
and quality of life of occupiers of buildings adjacent to secondary substation sites added on Sections
4.1.4, 4.1.5, 4.16 and 4.2. Information on what a condition survey report should consist of added on
section 3.1.1, Requirement of protection of substation building form environment conditions or damp
following demolition of adjacent building added in section 4.1.10, Contact number in any event likely to
compromise any UK Power Networks asset provided in Section 5.
Document transferred onto a new template and rules applied.
Version
1.0
Review Date
09/09/2016
Date
22/08/2013
Author
Helen Amare
Original
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Requirements for Third Party Works in the Vicinity of UK
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Document Number: EOS 07-0118
Version: 3.0
Date: 24/03/2017
Contents
1
Introduction ......................................................................................................... 4
2
Scope ................................................................................................................... 4
3
Glossary and Abbreviations ............................................................................... 4
4
General Considerations of Works around any Live Electricity Asset .............. 5
5
Construction Work near Substations................................................................. 6
5.1
Plan and Design of Construction Works ................................................................ 6
5.2
Assessment of Risk and Suitability of the Proposal ............................................... 7
5.3
Monitoring of Construction Works around Substations .......................................... 8
5.4
Considerations while the Construction Activity takes place .................................... 9
6
Construction Work near Cable Tunnels ........................................................... 11
6.1
Planning and Designing Construction Works near Cable Tunnels ....................... 11
6.2
Assessment Risk and Suitability of the Proposal ................................................. 12
6.3
Monitoring of construction works around Tunnels ................................................ 13
6.4
Considerations while the Construction Work takes place ..................................... 14
7
Construction work near Cable Bridges ............................................................ 15
7.1
Planning and Designing Construction Works near Substations ........................... 15
7.2
Assessment of Risk and Suitability Assessment .................................................. 15
7.3
Monitoring of Construction Works around Cable Bridges ..................................... 15
7.4
Considerations while the Construction Work takes place ..................................... 15
8
Construction Work near Underground Cables ................................................ 16
8.1
Planning and Designing Construction Works near substations ............................ 16
8.2
Assessment of Risk and Suitability of the Proposal ............................................. 16
8.3
Monitoring of Construction Works around Substations ........................................ 16
8.4
Considerations while the Construction Work takes place ..................................... 16
9
References ......................................................................................................... 17
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Document Number: EOS 07-0118
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1
Introduction
Third party works in the vicinity of existing UK Power Networks assets such as substations,
tunnels, cable bridges and underground cables need to be monitored and managed in order
to avoid compromising the electricity network. Electrical equipment, plant and some
structures are sensitive to vibration and ground settlement during adjacent demolition, piling
or heavy construction works.
This document sets out the survey, assessment, monitoring and control requirements for
works being carried out adjacent to and/or below UK Power Network’s assets. It highlights
the requirements for maintaining ventilation and plant/personnel access routes, fire
protection, E.M.F. and noise control when works are undertaken by a Customer in the
vicinity of UK Power Networks assets.
2
Scope
This standard aims to provide guidance to:



Developers undertaking works involving tunnelling, piling or excavation adjacent to
substations, cable bridges, tunnels and underground cables. This includes any
temporary works or plant necessary to undertake the main works that are likely to have
an adverse impact on UK Power Networks assets.
Developers planning to construct residential accommodation adjacent or above
132/33kV (Grid), 33/11kV (Primary) or 11kV/415V (Secondary) substations.
Developers regarding UK Power Networks’ requirements for surveys, controls, design
considerations, safe operation, replacement of plant and safety and quality of life of
occupiers of buildings adjacent to substation sites.
3
Glossary and Abbreviations
Term
Definition
Customer
Can be either a developer, a contractor or a consultant seeking to survey,
design, assess, monitor or undertake construction works in the vicinity of
UK Power Networks assets.
E.M.F
Electric and Magnetic Field
HSE
Health and Safety Executive
HSG47
Health and Safety Guideline 47:
Avoiding danger from underground services (cables and pipes)
NRSWA
New Roads and Street Works Act
PPV
Peak Particle Velocity
UK Power Networks
UK Power Networks (Operations) Ltd consists of three electricity
distribution networks:

Eastern Power Networks plc (EPN).

London Power Network plc (LPN).

South Eastern Power Networks plc (SPN).
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4
General Considerations of Works around any Live Electricity Asset
To ensure that the requirements outlined in this document are met, representatives from
UK Power Networks and the Customer shall meet on site to define, when pertinent, the
preparation the following:









A condition survey report of the UK Power Networks asset prior to the commencement
of the construction works;
Ground movement/settlement assessment report relating to the substation and
electrical assets;
Vibration monitoring reporting strategy;
Method statements describing the proposed works and construction methodology,
including any non-standard construction techniques envisaged;
Details where the construction methodologies for the proposed works involve
techniques which could result in ground-borne vibration in excess of the permissible
vibration limit;
Control measures should settlement or vibration exceed permissible limits;
Plant and personnel access routes, temporary arrangements during construction and
new access way arrangements for personnel and equipment;
Details on how ventilation routes will be protected;
Details on how dust and debris will be controlled.
Subject to the scale of the proposed works a team of experts will need to be assembled by
UK Power Networks to assess the Customer’s proposal. The resource required to do this
shall be identified at an early stage of the project. When various experts input is required,
it is important that the Customer keeps and shares a record of all Pre-works discussions.
Formal agreements can vary from a Party Wall Act award, Asset Protection Agreement or
License Agreement.
The condition of the structure shall be agreed by the Customer and by UK Power Networks
prior to the works commencing; rectification of any subsequent damage, depending on its
severity, discussed either during the works or upon their completion.
Upon completion of the works (e.g. excavation or tunnelling), a post-works survey of the
asset is to be carried out to establish the final condition of the structure. Subject to the
findings of the post-works survey, any damage deemed to have been caused by the works
shall be rectified by Customer at their expense.
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5
Construction Work near Substations
This section shall be read in conjunction with Section 4.
Where vibration, settlement and/or general impact to the substation exceeds tolerances or
adversely impacts operation, it may be necessary for the Customer to submit an application
for the substation to be relocated. If this does become necessary UK Power Networks
Connections can be contacted at [email protected].
5.1
Plan and Design of Construction Works
5.1.1
Asset Condition Survey
Surveys to assess the condition of the substation building or structure shall be carried out
prior to the works commencing and following completion. A written report shall be submitted
for UK Power Networks to contrast the condition of the asset pre and post works.
The condition survey reports shall record any signs of cracking, water ingress, and oil leaks;
photographic evidence shall be provided. The survey shall be visual only and no intrusive
investigations, opening up of plant or equipment will be carried out during the survey.
5.1.2
Geotechnical Report
The ground conditions around the substation building shall be understood in order to
substantiate the risk analysis of the proposals to be submitted by Customer; the
Geotechnical Report shall be submitted to UK Power Networks along with the proposal’s
explanatory documents. The submission of the Geotechnical Report will be required for
works impacting the foundations of the substation or when piling or excavations may alter
the condition ground supporting the substation.
As a minimum, the report will state the ground bearing capacity and composition of the soil
around/below the UK Power Networks assets.
5.1.3
Electric and Magnetic Fields survey (residential developments only)
To ensure that any proposed residential properties are safe to occupy, it is important that
an E.M.F. survey around the substation asset is commissioned by the Customer; this shall
establish the electrical and magnetic field levels and enable the design and incorporation
of screening where appropriate to protect occupants. This will also allow the consideration
of locating key living areas like bedrooms at “safe” areas in order to minimise exposure.
Guidelines published by the International Commission on Non-Ionising Radiation Protection
(ICNIRP, 1998), set the maximum permitted exposure levels to magnetic fields up to 360
microtesla [mT] and to electric fields up to 9000 volts [V] per metre.
Reference levels above which further investigation into screening and control is
recommended for the public are 100 mT for magnetic fields and 5000V per metre for electric
fields.
Small electricity distribution equipment such as UK Power Networks Secondary
(11kV/415V) substations typically produce magnetic fields up to 2mT close to their
boundary, occasionally more if built into another building. The fields fall rapidly with
distance, and within 1 to 2 metres from a typical substation, the fields associated with it are
usually indistinguishable from other fields present in homes.
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5.1.4
Noise Survey (Residential Developments only)
A noise survey shall be undertaken as part of the project planning process to establish a
baseline and understand what mitigation, where appropriate, is required to prevent noise
complaints once the property is occupied.
For reference, transformers can produce a low frequency hum (100hz). In extreme cases
this magnitude of noise can cause disturbance.
5.2
Assessment of Risk and Suitability of the Proposal
5.2.1
Ground Settlement and Displacement
The Customer shall provide a risk assessment based on a predicted settlement from
anticipated ground movement and/or percentage ground loss. From this assessment and
calculation, the Customer is to discuss with UK Power Networks whether settlement is likely
to cause damage to the substation structures or equipment.
For the assessment of the impact of the ground settlement, UK Power Networks follows
these guidelines:
>1:500 will have the potential to create minor cracking in building structures.
>1:750 settlement will have the potential to disturb sensitive equipment.
>1:1000 manufacturer’s maximum tolerance of electrical switchgear and
transformers.
For the purposes of assessing and monitoring UK Power Networks assets a 1:1000
differential settlement trigger limit shall be set.
5.2.2
Access and Egress Routes
The substation building and plant are regularly visited by UK Power Networks operatives in
order to carry out routine maintenance and cleaning. Less frequently it may be necessary
to replace plant or equipment in order to upgrade it or carry out major repairs. For these
reasons it is important that maintenance of the existing personnel and plant access routes
are considered in the final design. An equipment replacement strategy must always be in
place.
Where a substation is located below street level a 2 x 3m minimum plant access area must
be maintained. Access to this area must be possible during and after the completion of the
development. This will be the way for key plant to be removed and replaced using a lorry
mounted crane. A clear headroom of 3.25m is to be maintained above this access point.
Where required the plant access area can be enclosed with a suitable hatch or removable
covering providing that no one section exceeds recommended maximum personal lifting
limits.
Any permanent changes to access arrangements will need to be formally recorded on the
deeds / lease of the substation; this will need to be arranged through UK Power Networks’
Property and Consents team.
In order to ensure safe egress from the property during construction and occupation, UK
Power Networks do not recommend that any access or egress point passes any doors or
ventilation louvres leading directly from the substation building.
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5.2.3
Ventilation
If a diversion is required, demonstrable proof must be provided by the Customer that the
revised ventilation route does not compromise the cooling of the substation or any other
electrical asset.
The transformers can develop up to 13kW of heat. Switch gear operates safely at a
maximum temperature of 25 degrees Celsius.
Refer to EDS 07-0102 Secondary Substations Civil Design Standard for guidance on
ventilation systems.
5.2.4
Fire Protection
Four-hour passive fire protection is to be maintained/installed/provided between the
substation and the property.
Ventilation systems shall be considered an extension and an integral part of the substation
when considering fire risks.
5.2.5
Structural Supports
The use of the substation building/structure to structurally support a structure above is not
permitted as the development property could be compromised should there be a plant
failure resulting in the loss or damage of a supporting wall.
5.3
Monitoring of Construction Works around Substations
An Instrumentation and Monitoring plan shall be produced by the Customer and agreed
with UK Power Networks one month prior to the commencement of the works on site. Where
required the Instrumentation and Monitoring Plan shall include agreed trigger levels
(green/amber/red) with associated action plans.
The Customer shall have an Emergency Action Plan agreed with UK Power Networks
should settlement or vibration exceed agreed limits.
5.3.1
Structural and Settlement/Displacement monitoring
To ensure that substation building and plant/equipment are not compromised by settlement,
it is essential that the structure’s sensitive areas are monitored and control measures are
agreed.
Structural and ground settlement monitoring is to take place using an agreed levelling
process at each corner of the structure; as a guideline, these shall be at the mid-point along
each longer wall as well as incorporating any other locations agreed in the pre-works
discussions. Monitoring to take place at an agreed frequency and the results are to be
communicated to the UK Power Networks representative for the scheme.
The monitoring shall continue for a period of two months after the works are complete or
until the readings are stabilised, whichever is the greatest.
Where settlement is likely to affect plant and equipment in the building, in order to monitor
movement within the switchgear surface, mounted strain gauges are to be installed on the
switchgear busbar casings.
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The properties of cast iron are to be used to set the safe working stress as it is less
malleable than copper and will provide an adequate factor of safety in the monitoring. The
cast iron properties to be considered are 38N/mm2 in tension and a Young's modulus of
100x103 N/mm2. In order to give some reaction time before the safe working stress is
reached an alarm trigger level of 75% of the safe working stress shall be set. Using these
figures the trigger level will be 300 microstrain.
A self-temperature compensated strain gauge shall be used to minimise the effect of
temperature on the strain gauge readings.
5.3.2
Vibration Monitoring
A Vibration Monitoring Plan with green/amber/red trigger levels between 0 to 7 mm/sec
shall be produced by the Customer and agreed with UK Power Networks one month prior
to the start of works on site. The Customer shall provide UK Power Networks with vibration
monitoring reports on an agreed frequency.
A suitable channel seismograph is to be used to monitor vibration within the substation.
Suitable and accessible points around the building structures and/or plant shall be selected
for vibration monitoring. Vibration monitors, measuring the Peak Particle Velocity (PPV) in
three orthogonal axes (2 horizontal and 1 vertical), shall be fixed to the switchroom floor,
near the centre of the line of switchgear, on the busbar casing where it is accessible and
other vibration sensitive areas or equipment within the substation; for example protection
panels or on the external wall of a secondary substation.
Areas, including the switchroom, containing plant particularly susceptible to the effects of
vibration should be chosen as the location for monitoring the vibrations. The seismograph
shall allow the vibration to be monitored remotely and in real time.
The maximum PPV must be 7 mm/sec. An audible alarm shall be linked to the monitoring
system and sound when a 7 mm/sec or greater is detected. The audible alarms shall be
made available for immediate reaction.
The results of a 30 second vibration measurements are to be analysed to provide the
maximum PPV recorded over 15 minute periods. The summary results are to be presented
in a digital format. In order to ensure accurate and consistent results, substation buildings,
equipment and plant vibration monitoring shall be measured and assessed in accordance
with BS 7385-2:1993 and BS ISO 4866:2010.
5.4
Considerations while the Construction Activity takes place
If the system or plant mal-operates through differential settlement or where excessive
settlement is recorded, work shall stop immediately and support to the structure shall be
provided by the Customer; continuation of the work will only proceed following consultation
and agreement with UK Power Networks.
Where the structure of the substation building has been exposed following demolition of an
adjacent or parent building, it will be necessary for the Customer to provide additional
protection. In order to ensure that the building remains water-tight and weather resistant.
This is to guarantee the plant and equipment, which is rated for indoor use only, is not
exposed to inclement environmental conditions or damp.
© UK Power Networks 2017 All rights reserved
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Settlement in excess of the agreed levels or any action causing damage to the structure
shall be investigated and suitable temporary support installed by the Customer (at their cost
and immediately), until a permanent solution and repair can be carried out.
Action by the Customer will be required to ensure that the settlement is stabilised and
controlled and an alternative work method adopted.
If the found that the busbars are experiencing physical strain contact Fore Hamlet Control
Centre (0800 3163105 or 0161 7740475).
Work causing the excessive vibration shall be stopped and an alternative method of work
adopted. Work likely to cause the high vibration level shall be stopped after the alarm
sounds. UK Power Networks and the Customer shall react to the alarm(s) when they are
first generated, ensuring that they are not false alarms (e.g. the strain gauge has become
detached).
5.4.1
Protection from Dust and Debris
The substation building and plant are to be protected from dust and debris during and after
the construction works. Any debris resulting from the proposed works shall be removed by
the Customer.
The Customer shall not allow any debris to be left around UK Power Networks substations
and interfere with substation access. Always keep the area around UK Power Networks
substation free of construction materials and debris.
Any physical protection required to be erected within the substation building must be
undertaken by a contractor approved by UK Power Networks to work within a live substation
environment.
5.4.2
Access and Egress during Construction Works
It is important that maintenance of personnel and plant access routes open. An equipment
replacement strategy must always be in place, even during the construction stage of the
development scheme.
Where a substation is located below street level a 2 x 3m minimum plant access area must
be maintained. Access to this area must be possible during and after the completion of the
development. This will be the way for key plant to be removed and replaced using a lorry
mounted crane. A clear headroom of 3.25m is to be maintained above this access point.
In order to ensure safe egress from the property during construction, UK Power Networks
do not recommend that any access or egress point passes any doors or ventilation louvres
leading directly from the substation building.
5.4.3
Ventilation
In order to ensure that transformers do not overheat during operation it is important that
ventilation routes and openings are maintained clear. (e.g. louvered vent panels).
If a temporary diversion is required, the Customer shall ensure the revised ventilation route
does not compromise the cooling of the substation or any other electrical asset.
© UK Power Networks 2017 All rights reserved
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6
Construction Work near Cable Tunnels
This section shall be read in conjunction with Section 4.
Where there is potential to damage to the tunnel, excessive settlement or uncertainty of
impact of the third party works, UK Power Networks may request that a legally binding Asset
Protection Agreement is drawn up.
6.1
Planning and Designing Construction Works near Cable Tunnels
6.1.1
Line and Level Survey
Due to changes in topology and surface features, the tunnel’s relative referencing system
may get altered in time, making underground asset records true only at the time of
installation of the asset; for this reason positive identification by a specific site survey shall
be undertaken by the Customer; this will consist of a line and level survey of the tunnel.
True location of the tunnel will allow the exact determination of the exclusion zone; this is
of utmost importance where boreholes, piling, basement excavation and/or tunnelling is
likely to be carried out within 10m from the edge of the tunnel.
6.1.2
Internal Condition Surveys
An internal condition survey of the tunnel shall be carried out. The location and length of
the survey shall be agreed between the Customer and UK Power Networks prior to the
construction phase. This pre-condition survey will form part of the record which will enable
comparison with the subsequent condition surveys to ultimately assess the effects of the
works on the tunnel. In order to establish if there has been any additional damage or defects
caused by the works, a condition survey of the tunnel will also be carried out after
completion of the third party works. Interim surveys may be agreed subject to the risk and
scale of the works being undertaken.
The purpose of these surveys shall be to visually examine and record the general condition
of the tunnel internally. The surveys shall be purely visual and no intrusive investigations,
opening up or monitoring will be carried out.
The surveys will identify:








Delamination of the lining segments.
Corrosion or other staining.
Cracks and fractures.
Deformation and displacement.
Water ingress or evidence of such as dampness.
Movement/displacement of segments (open joints).
Loose or missing bolts.
Any other obvious visible defects.
Subject to the findings of the post-works survey, any damage deemed to have been caused
by the vibratory, tunnelling or excavation works shall be rectified by the Customer at their
expense.
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6.1.3
Geotechnical Survey
In order to substantiate the risk analysis to be submitted by the Customer, the Geotechnical
Report of the area shall be submitted to UK Power Networks.
To locate exact position of shallow tunnels, trial holes shall be carefully excavated, possibly
by hand tools.
6.2
Assessment Risk and Suitability of the Proposal
As tunnels are such critical assets it is expected to see Category III checks and reports
being undertaken as the design progress. The following general guidelines shall be taken
into account at the design stage:
 Adjacent building’s foundations to be designed to avoid stresses being transferred to
tunnel structure. This shall require spread footings or piles being founded below invert
of tunnel.
 Unless otherwise specified, for project planning purposes, a 10m diameter cylinder with
same tunnel’s centre shall be kept clear from increased loads directly above the tunnel.
The diameters of the tunnel and offsetting cylinder vary at different locations.
 Edge of piles to be designed at least two metres away from outside of the tunnel
alignment annulus and associated structures; the piling loads to be transferred below
to horizontal centre line of the tunnel.
 For the ground around the tunnel’s to top half section, heavy permanent loading shall
not occur within a 3m distance from the outside of the tunnel
 Structures proposed in the vicinity of UK Power Networks tunnels and alignment shall
be designed to prevent the impact E.M.F. interference.
6.2.1
Impact from Adjacent Ground Works and Ground Level Increased Loads
Ground movement associated with the third party proposed works may impose radial and
longitudinal deformations and stress changes on the tunnel. The potential impacts of
ground movements on the longitudinal and transverse response of tunnel shall be assessed
and reported to UK Power Networks. The report commissioned by the Customer shall
inform and advice on:




Risk assessment based on the predicted horizontal and vertical settlement.
Calculation of heave and loading to tunnel structure from the proposed works.
Assessment of the stress increase on the tunnel crown.
Consideration of the capacity of the tunnel lining to resist the effect of the surcharging
and/or movement.
Predicted tunnel settlements exceeding 20mm over a radius of curvature of less than 10km
shall require specific structural analysis to demonstrate that the increase in stress imposed
on the tunnel structure do not exceed its capacity.
The UK Power Networks tunnel shall be assessed as a "stiff ring" without the added
flexibility (or stiffness reduction) attributable to the joints in order to compare the hoop force,
axial forces and bending moments to the capacity of the material forming tunnel lining and
general construction. From this assessment and calculation, it is to be established whether
this settlement is likely to cause damage to the tunnel.
Where bolted connections are present, a flexible tunnel model shall be used to assess the
stress on the connection bolts. Where there is no bolted connection, no bolt stress
calculation will be required although an estimate of the opening up of the joints between the
sections will be required for both bolted and non-bolted joints.
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For the purposes of calculation, the pre-development status of the loading shall be
considered neutral and any reduction or increase in load throughout the construction of the
development shall be considered.
6.2.2
Impact from Adjacent Tunnelling Works
Same as detailed in Section 6.2.1.
For the purposes of calculations an industry standard Moderately Conservative
percentage loss for the material through which the Customer’s tunnel is being
constructed shall be used. Typically this is considered to be 1% although this may vary for
some geological strata.
6.2.3
Access and Egress Routes
The tunnel plant are regularly visited by UK Power Networks operatives in order to carry
out routine maintenance and cleaning or less frequently to replace plant or equipment. It is
important that existing personnel and plant access routes are maintained clear and the
Customer’s scheme is complete. An equipment replacement strategy must always be in
place.
Where access to the tunnel through a hatch, a 2 x 3m minimum plant access area must be
maintained. Access to this area must be possible during and after the completion of the
development. This will be the way for plant to be removed and replaced using a lorry
mounted crane. A clear headroom of 3.25m is to be maintained above this access point.
Any permanent changes to access arrangements will need to be formally recorded on the
deeds / lease of the substation; this will need to be arranged through UK Power Networks’
Property and Consents team.
6.2.4
Ventilation
The Customer shall make sure that the ventilation routes are not compromised.
6.3
Monitoring of construction works around Tunnels
Depending on the results of the preliminary investigations, an instrumentation and
monitoring plan may be needed along with documented agreement on the liabilities and
details of the mitigation works to manage the impact.
The Instrumentation and Monitoring plan for the tunnel shall be produced by the Customer
and agreed with UK Power Networks one month prior to the commencement of the works
on site. Where required the Instrumentation and Monitoring Plan shall include agreed
trigger levels (green/amber/red) with corresponding action plans. The Customer shall agree
with UK Power Networks the frequency of readings and shall provide UK Power Networks
with reports.
The Customer shall have an Emergency Action Plan agreed by UK Power Networks should
settlement or vibration exceed agreed limits.
© UK Power Networks 2017 All rights reserved
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Requirements for Third Party Works in the Vicinity of UK
Power Networks Assets
Document Number: EOS 07-0118
Version: 3.0
Date: 24/03/2017
6.3.1
Structural, Settlement and Displacement
An electro level monitoring is recommended to monitor the settlement and ovalisation inside
the tunnel.
The tunnels shall be monitored after completion of the works for a period to be agreed with
UK Power Networks depending on the scale of the works being undertaken. The post-works
monitoring period will be at least than three months or until the readings are stabilised,
whichever is longer.
6.3.2
Vibration
Tunnels in the vicinity of the construction site respond to vibrations caused by the
construction activity with varying results.
Potential vibration effects resulting from proposed construction works is dependent upon
the method of installation.
Construction work shall be carried out to minimise vibrations experienced in the tunnel and
associated structures. Maximum vibration to be limited to 7mm/sec peak particle velocity (PPV), and verified by means of monitoring.
To ensure that tunnel structure and plant/equipment housed within are not damaged by
vibration, it is essential that the structure’s sensitive areas are monitored and control
measures are agreed.
6.4
Considerations while the Construction Work takes place
The following items outline other general requirements for the works by third parties in the
vicinity of UK Power Network tunnels while the construction works take place:



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Tunnel entry points to be kept clear of obstructions and access to be available at all
times.
Construction plant and machinery not to work within 2m (concentric zone) of the tunnel
alignment annulus or associated structures, UK Power Networks MUST be informed in
advance of any works and in sufficient time to assess the works and any possible
impacts to the structural integrity of the asset in question – this advance notification
duration will be dependent on the works to be undertaken.
Vehicle forces, e.g., weight and braking forces not to be transmitted through the ground
into the tunnel or associated structures.
The Customer shall submit weekly vibration monitoring reports to UK Power Networks
during construction and during a post work agreed period.
UK Power Networks are to be advised that an emergency, potential emergency or
significant unplanned event has occurred, such us:

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
Failure/Deformation of tunnel lining.
Poor ground conditions/uncontrolled loss of ground into tunnel.
Major water inflow into tunnel.
Deteriorating ground conditions.
Fire – with potential to damage lining structure.
Potential long term stoppage of tunnelling in zone of influence of UK Power Networks
tunnels due to difficulties due to machinery breakdown.
Ground movements in excess of the agreed value.
© UK Power Networks 2017 All rights reserved
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Requirements for Third Party Works in the Vicinity of UK
Power Networks Assets
Document Number: EOS 07-0118
Version: 3.0
Date: 24/03/2017
7
Construction work near Cable Bridges
This section shall be read in conjunction with Section 4.
7.1
Planning and Designing Construction Works near Substations
Assessments of the cable bridge structures and the cables on the bridge shall be carried
out to demonstrate that the predicted effects from ground movements induced by proposed
third party works are within acceptable limits. Differential settlement across the width of the
bridge foundation shall be considered.
Based on the structure type, a suitable assessment method shall be used to evaluate the
cable bridge structure response to the effects of ground movements caused by the
proposed construction works.
7.2
Assessment of Risk and Suitability Assessment
Analysis of the structure shall be carried out to calculate the change in stress due to ground
movement. Induced stresses to be confirmed during the assessment and compared with
allowable material stress.
7.3
Monitoring of Construction Works around Cable Bridges
As agreed during the Planning and Design stage.
The Customer shall have an Emergency Action Plan should settlement or vibration exceed
agreed limits. The plan shall be discussed and agreed prior the commencement of the
works.
7.4
Considerations while the Construction Work takes place
Horizontal movement of a cable bridge is more critical than vertical movement in causing
structural and cable damage.
Horizontal movements of abutments and piers must be controlled in order to avoid structural
damage and tension on cable joints.
© UK Power Networks 2017 All rights reserved
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Requirements for Third Party Works in the Vicinity of UK
Power Networks Assets
Document Number: EOS 07-0118
Version: 3.0
Date: 24/03/2017
8
Construction Work near Underground Cables
This section shall be read in conjunction with Section 4.
8.1
Planning and Designing Construction Works near substations
UK Power Networks shall be consulted at an early stage and a copy of the cable plan
indicating locations of any cables buried in the proposed areas obtained prior to the works
concerned being carried out. For information contact [email protected].
If it becomes necessary to move cables or meter positions UK Power Networks
Connections can be contacted at [email protected].
8.2
Assessment of Risk and Suitability of the Proposal
Movement of underground cables resulting from excavation works shall not exceed a
change in slope steeper than 1:1000 (maximum slope at any point on the cable run). This
applies to fluid filled cables and paper/lead and gas insulated cables
If construction works are planned within an existing easement area or any type of legal right
relative to the cables, it is likely that a license agreement needs to be put in place to allow
the works to commence.
8.3
Monitoring of Construction Works around Substations
As agreed during the planning stage.
The Customer/Customer shall have Emergency Action Plan agreed with UK Power
Networks should settlement or vibration exceed agreed limits.
8.4
Considerations while the Construction Work takes place
Construction works should not cover, enclose or disturb UK Power Networks cables as
works to repair or replace these cables may be required in the future which could result in
considerable disruption to the property occupier if the cables are not easily accessible.
Damage to underground cables during excavation works can result in serious injury to
people at work and disruption of electricity supplies. When work is carried out near
underground cables, adequate precautions must be taken. Excavation works above and
adjacent to live cables shall be carried out in accordance with the HSE guidance document
HSG47, by a suitably competent Customer with demonstrable training in NRSWA.
Shear loads on cables and tensile force to joints during excavation and tunnelling works
shall be avoided.
If a cable damage occurs this must be reported immediately to the following numbers:
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London: 0800 780 078
Kent, Sussex and Surrey: 0800 783 8866
East of England: 0800 780 078
© UK Power Networks 2017 All rights reserved
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Requirements for Third Party Works in the Vicinity of UK
Power Networks Assets
Document Number: EOS 07-0118
Version: 3.0
Date: 24/03/2017
9
References
BS ISO 4866:2010
Mechanical vibration and shock. Vibration of fixed structures.
Guidelines for the measurement of vibrations and evaluation of their
effects on structures
BS 7385-2: 1993
Evaluation and measurement for vibration in buildings Part 2. Guide to
damage levels from ground borne vibrations.
BS 5228-1:2009+A1:2014
Code of practice for noise and vibration control on construction and
open sites. Noise
EDS 07-0102
Secondary Substation Civil Design Standards
EDS 07-0105
Grid and Primary Civil Engineering Standards
© UK Power Networks 2017 All rights reserved
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