Site Rules
Regulation
Excavations
Page 1 of 11
2. Excavations
Contents:
1. Introduction
2. Organizational aspects
3. Risk inventory and evaluation
4. Safety aspects of pit and trench digging
5. Excavations in the vicinity of cables
6. Excavations in the vicinity of pipelines
7. Excavations in the vicinity of sewers
8. Excavations in the vicinity of railway tracks
9. Excavations in the vicinity of high-voltage masts
10. Excavations in and near greenery
11. Work to be performed in pits and trenches
12. Confined space
13. OBL Acceptance Committee
1. Introduction
 This regulation covers the SHE aspects of excavations, both IBL (Inside Battery Limits)
and OBL (Outside Battery Limits).
 Excavations: this is taken to mean all digging and earth-moving operations, etc., below
a depth of 0.2 m below ground level. This therefore includes soil drilling operations,
installation of earth electrodes, etc.
 Legal provisions:
- Working Conditions Decree: Art. 3.29 – section 4, Art. 3.30 and Art. 3.31
- Working conditions policy rule 4.2-2: Assessment method for exposure to toxic
substances when working in or with contaminated soil
- Working Conditions Information Sheet 22: Working with contaminated soil
 Site Rules:
- Chapter ‘Soil and infrastructure’
- Chapter ‘Work permits’.
 The laying of cables, lines, sewers, etc. as well as backfilling of trenches and pits shall
be subject to the regulations issued by the owner.
This regulation applies to all excavations in so far as specific excavation regulations of
owners of cables, pipelines, sewers, etc., do not include deviating or supplementary
provisions. If they do, the provisions from the excavation regulations of the
owner in question (SABIC Pipelines BV, Vynova, USG, EPG, Gasunie, WML, KPN, Air
Liquide, etc.) take precedence.
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Site Rules
Regulation
Excavations
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2. Organizational aspects
 For excavations a work permit is required. If the excavations extend over the areas of
several area managers, the work permit procedure applies in each of these areas.
 The head of the commissioning department specifies the required safety precautions
on the work permit.
 Use shall be made of the "Aanvraag graafinformatie” form (Excavation information
application form) to obtain the required information from Mapping & Registry RHDHV Sitech Site Office. The excavation information provides information on the routes of
pipelines, cables, sewers, railway tracks, etc., while it also specifies what agencies are
to be notified prior to the start of the excavation.
 Before any excavation can be started, it should be investigated whether the soil in
which this will take place is contaminated. This investigation can be requested by
means of the form “Aanvraag bodemonderzoek voorafgaand aan bouw, graaf of
sloopwerkzaamheden” (Request for soil investigation prior to building, excavation or
demolition work).
 Before resuming work after an interruption, it shall first be established that the situation
has not changed, that the precautions taken are still in place, and that the work permit
or permits are still valid.
 Once the excavation works have been completed, the applicant sends the excavation
information back to the Mapping & Registry RHDHV department, which is part of the
Sitech Site Office. The associated drawing(s), stating any deviations found in
comparison with the actual situation, which are obtained by surveying, must be
supplied to Mapping & Registry RHDHV - Sitech Site Office for processing in SiteView
no later than 4 months after execution. This also applies to new objects.
 All abnormal occurrences, including damage observed or caused to underground
pipelines, cables, sewers, etc., must immediately be reported to the head of the
commissioning department. The excavation work must temporarily be halted when an
abnormal occurrence takes place.
3. Risk inventory and evaluation
 If the head of the commissioning department decides that the hazard and risk aspects
cannot normally be controlled, these aspects are to be analyzed prior to the work
(TRA, JSA) and any safety precautions arising from such analyses must be taken.
 SHE aspects to be taken into account include:
o zone areas (gas and dust explosions)
o underground pipelines, cables, sewers, etc.
o contaminated soil
o groundwater
o undercutting due to leakages
o changes to cable routes etc.
o environmental influences (plant, building, traffic, railroad, etc.)
o cable routes etc. being loaded with the weight of excavation equipment,
material and transport means
o greenery (durability, view, appearance).
o risk of people getting buried under falling earth
o poisoning or asphyxiation (dangerous fumes or gases)
o people tripping or falling or vehicles driving into excavations
 If the depth of a pit or trench exceeds 1 m, earth-retaining structures are to be applied
(strutting, shuttering or dam walls) or a safe slope angle is to be used.
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Regulation
Excavations
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4. Safety aspects of pit and trench digging
4.1 Soil type
 All Chemelot sites are regarded as ‘stirred soil’.
This means that the soil pressure must never exceed 200 kN/m2 (2 kg/cm2).
4.2 Measure to prevent slope cave-ins
 In the absence of adverse conditions, the ratio of height (a) to horizontal distance (b)
as given in the table applies.
Soil type
Loose or stirred
Sand or loam
Clay



Depth
below
ground level
1–4m
Slope not
steeper than
(a : b)
1:1
1 – 1.5 m
1.5 – 4 m
1.5 : 1
1:1
a
b
Stepped excavation is allowed if sloped excavation is impossible because of
the presence of underground infrastructure.
In case of
- excess water (groundwater, precipitation, frost, thaw, etc.)
- heavy top load at or along the intersecting line of slope and ground level
(buildings, installations, etc.)
- inhomogeneous and/or layered soil
- vibrations (excavation equipment, traffic, rail transport, etc.)
- soil deterioration (prolonged open excavation)
the risks involved are to be determined and supplementary measures are to be taken.
When the excavation depth exceeds 4 m the risks are to be determined on the basis of
the soil properties as established and the conditions under which the excavation takes
place and supplementary measures must be taken. This will usually result in the use of
earth-retaining structures.
Undercutting of slopes is not allowed.
4.3 Earth-retaining structures
 Earth-retaining structures must
- be made of appropriate materials that are suitable for the purpose
- be adequately dimensioned
- be strong enough to guarantee a safe workplace.
 The design of earth-retaining structures is to be determined separately for each
individual case, taking into account the results of the risk inventory and evaluation (see
3.). The contractor must demonstrate the suitability of the earth-retaining structure on
the basis of calculations.
 Components of earth-retaining structures must not be loaded in ways other than that
for which they were originally meant, unless they are designed for such extra loads.
 Provisions installed to prevent caving in of pit or trench walls must not be removed as
long as people are locally present in a pit whose bottom is more than 1 m below
ground level.
 When use is made of hydraulic jacks, an effective pressure-limiting device is to be
applied.
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Regulation
Excavations
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4.4. Soil drillings and installation of earth electrodes
 If it is suspected, based on the excavation information, that underground infrastructure
is present within a distance of 5 m from the point at which the work takes place, this is
to be verified by digging trial trenches. For further information see the requirements
formulated in chapter 5.
4.5 General instructions
 When the intersection line of slope and ground level is in or near a road surface,
adequate measures must be taken to prevent parts of the road surface falling into the
pit or trench.
 Next to the edges of a pit or trench with a depth exceeding 1 m, a safety strip of at
least 0.5 m wide is to be provided, which must be kept free of earth and materials,
unless a closed wall structure is applied that projects at least 0.15 m above ground
level.
 The excavation must be provided with an adequate number of safe access and exit
points, for instance by means of ladders. A trench with a width at ground level of more
than 0.8 m must be provided with an adequate number of suitable crossings, also
depending on the length, location and depth of the trench. The head of the
commissioning department is to be consulted about this.
 Crossings should be of adequate strength and have a width of at least 0.6 m.
Alongside these crossings a suitable guard rail or fencing is to be provided to a height
of at least 1 m, of such a construction that the danger of objects falling into the pit or
trench is also prevented.
 Slopes and earth-retaining structures must be inspected daily and after work
interruptions caused by adverse weather conditions and where necessary they must be
repaired.
 Excavation equipment and the like must maintain such a distance from the trench or pit
and be positioned in such a way that there is no risk of collapse of cave-in of the slope.
5. Excavations in the vicinity of cable routes
5.1
General
The electrical engineering aspects as described in this section apply when excavation work is
carried out within a distance of 5 m from the cable route. The excavation work is described in
section 1.2.
Cables must be provided with sound, non-damaged insulation to prevent contact with live wire,
short-circuiting, etc. Damage to the insulation may immediately or eventually result in a
dangerous situation, such as short-circuiting, earth leakage and/or the risk of contact. The
cable route manager must be informed immediately of any damage. Inside battery limits (IBL)
the officer responsible for electrical engineering in the plant in question is the cable route
manager; outside battery limits (OBL) the Sitech Site Office manager is responsible for cable
route management.
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Regulation
Excavations
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5.2
Preparations
All excavations require sound preparations. Examples of the matters to be considered are:
- The head of the commissioning department evaluates the risks to determine whether a
cable watch is needed. The cable watch must demonstrably and specifically have been
instructed for this purpose. The commissioning department instructs the cable watch on the
local risks.
- Besides the site safety instructions and the plant safety instructions, the digging crew must
also observe the specific instructions received from the cable route manager or the OBL site
manager.
Excavation information and/or a map showing the (underground) cable routes gives the most
accurate information possible about all known underground cable routes, sewers, pipelines,
etc. However, it does not indicate through what areas the routes pass and who is responsible
for the cables in these routes. Information about the cable route managers can be obtained
from the department supplying the excavation information and/or the map showing the
(underground) cable routes; they can supply sectional diagrams of the cable routes that
indicate the number of cables, the cable data and the cable owner, on the basis of which the
responsible cable route manager can be traced.
5.3
Requirements / Instructions
Excavation personnel may perform digging operations only if they have received the general
site instructions but have also have been instructed on:
- the nature of the work;
- specific risks in relation to the work;
- specific (safety) regulations relating to the work
- the local situation;
- specific (safety) instructions provided by the cable route manager.
The instructions received must be recorded in the Safety Passports of the employees involved.
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Regulation
Excavations
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5.4
Procedure for excavation work
The party that is responsible for the order:
 discusses the work with the permit provider;
 checks, on the basis of the excavation information, whether all ticked agencies have been
informed of the work;
 determines whether a RIE/JSA is needed for special parts of the work, for instance
excavations deeper than 80 cm;
 checks whether written permissions from the area managers/agencies are available;
 takes care of the work permits and checks, together with the permit providers, whether all
data are correct;
 takes account of all attention points specified in chapter 5;
 verifies whether all instructions mentioned in section 5.3 have been received;
 discusses the plan of action, the location of the cables, their number, and their depth with all
excavation personnel;
 orders manual digging of trial trenches in accordance with the directions of the cable route
manager and has the resulting data recorded in the excavation information.
If cable route deviations are observed, this is to be reported as soon as possible, but in any case
before the trench is backfilled, to the party responsible for the order and the cable route manager.
If cables no longer lie in the cable bed, they should be adequately (minimally at one-metre
intervals) be supported or be suspended.
5.5
Machine excavations
Machine excavations are permitted only if:
 written permission has been obtained from the cable route manager and
 the exact position of the cables has been determined by means of manually dug trial
trenches and
 a distance of 1 meter beside the cables is observed and
 a distance of at least 0.3 m above the cables or 0.1 m above the cable protection cover,
covering bricks, tiles, etc. , if present, is observed.
This should be in conformity with the following figure, where the shaded area represents the
area where digging must take place manually.
Ground level
Protection cover
30
cm
20
cm
See *
100
cm
100
Cables
cm
Zie *
* Note:
If a manual trench is dug in longitudinal direction beside the cables over the entire length of
the cable route, so that the exact location of the cable route is determined, the distance of 1 m
can be reduced to 0.3 m for machine excavations.
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Regulation
Excavations
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Within a radius of 0.3 m around the cables machine excavation is therefore never permitted.
Do not forget to dig trial trenches perpendicularly crossing the cable route in order to detect
parallel cables that are just outside the cable route.
5.6.
How to act in other situations
In the situations described below the cable route manager or the OBL site manager is to be
alerted, the work is to be stopped and the surrounding area is to be evacuated and cordoned off:
5.6.1 Cable damage or threat of cable damage
If a cable or sleeve threatens to be damaged, or is already damaged, the work must be
stopped immediately and the surrounding area must be evacuated and cordoned off to avoid
injury caused by contact and/or bursts of flame due to short-circuiting. This should be treated
as an alarm situation, it being strictly prohibited to come near, touch or move the cables or
sleeves. The permit provider and the cable route manager must be alerted immediately. They
will take further action. The cable will be rendered electrically safe and be repaired. After repair
and after having received permission from the head or the direct supervisor of the
commissioning department the work can be resumed.
5.6.2 Underground leakage
If underground pipeline leakages are observed, the work must be stopped immediately, the
surrounding area must be evacuated and cordoned off and the cable route manager must be
alerted. Care should be taken because initially it will not be known what liquid is released and
what acute and chronic health effects it may have. Another reason to be careful is that the
presence of liquid may give rise to short-circuiting in case of cable damage.
The cable route manager will take any further action required, for instance to determine the origin
and the nature of the liquid, to empty the trench, to check the cables for damage, if necessary
after first rendering them safe, and to eliminate the leakage.
5.6.3 High groundwater level
If a cable trench fills up with water due to high groundwater levels or heavy showers, the work is
to be stopped and the cable route manager is to be alerted. To avoid the risk of electrocution,
work should never be continued in a flooded trench.
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Regulation
Excavations
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5.6.4 Subsidence
If, for whatever reason, subsidence has taken place, the cable route manager must be
consulted about measures to be taken to support the cables and prevent cable damage. The
cable route manager will also initiate actions to establish the cause of subsidence and prevent
further subsidence.
5.6.5 Nekaldiet sleeves.
If a NEKALDIET sleeve is found during excavation work, the work is to be stopped
immediately because of the explosion risk and the cable route manager is to be alerted.
Sketch of Nekaldiet sleeve:
Top view
Specific
characteristics:
 flat lid
 Richels in deksel
Side view
Photos of Nekaldiet sleeve:
Top view
Bottom view
5.7
Backfilling of trenches
The head of the executing department ensures that accurate measurement of new and/or
removed and/or modified cables or deviating situations takes place and that the as-built
situation thus found is directly included in the various drawings.
The means used to support the cables during the (excavation) work shall be removed during
backfilling.
Care must also be taken that the earth beneath the cables is properly compacted. The permit
provider and/or the cable route manager have the right to order opening of the trench if
suspicious circumstances are observed.
5.8
Handing over of work
When work and the associated responsibilities are handed over, the new responsible officer
shall be given all information about the activities that is relevant for safety and for proper
progress of the work.
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Regulation
Excavations
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NB:
Before resuming work after an interruption, it shall first be established that the situation has not
changed, that the precautions taken are still in place, and that the work permit or permits are
still valid.
6. Excavations in the vicinity of pipeline routes
 On the instructions of the route manager, trial trenches shall be dug manually
perpendicularly across the pipeline route.
 The top layer may be removed mechanically up to a depth of at most 0.2 m.
 Mechanical removal of the layers below is allowed only after hand-dug test holes have
been made.
7. Excavations in the vicinity of sewers
 Before excavation work is carried out, information must be obtained from the sewer
manager or owner about the depth at which the sewers are located.
8. Excavations in the vicinity of railway tracks
For excavation work below or in the vicinity of railway tracks, earth removal conditions and
zones have been defined as shown in the figure below.
Other stipulations:
 Based on the risks, the head of the commissioning department determines whether a
railway look-out man is necessary.
 Besides the plant and site safety instructions, the excavation personnel shall also
observe the instructions issued by the head of the commissioning department.
 For the laying of pipelines, cables, sewers, etc., in the shaded area prior permission of
the OBL Acceptance Committee shall be obtained.
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Regulation
Excavations
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Consult with Park Assets/Site Infra for
excavations within 15 m of the track centre.
Work permit mandatory
within +3 m loading gauge!
Track centre
* Mandatory work permit with specific points to be noted when
working within +3.00 m loading gauge (= 5.50 m from track centre)
2.50 m
loading gauge = 2.50 m
3.00 m
Ground level
Distance from
track centre (m)
Excavation
zone boundary (m)
2
3
4.5
7
10
12
15
ground level
-0.40
-1.00
-2.00
-3.20
-4.00
-5.20
Excavation zone for which
no advice is needed
For earthwork in the shaded zone
a geotechnical investigation is necessary.
Typical dimensions:
Track width: 1.43 from rail to rail
Sleeper width: 2.60 m
Loading gauge: width 2.50 from track centre, height 4.80 m
December 2015
2.00 m from the track centre an imaginary line is drawn
at a slope of 1 :25. At a distance of 14.5 from the track
centre this line reaches a depth of 5.00 m below ground
level. For excavation work that passes this line a
geotechnical investigation of the railway track stability is
required.
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Regulation
Excavations
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9. Excavation work in the vicinity of high voltage masts
 Activities may only be carried out in the hazardous zone of a high voltage line following
written permission of the manager of the line (Essent Intermediate). The hazardous
zone is 50 metres on each side, measured from the centre of the high voltage line.
Where equipment (including hoisting equipment) is used with an overturn radius
greater than 35 metres, the hazardous zone shall be 1.5 times the overturn radius.
10. Excavation work in and in the vicinity of greenery
 These activities shall take place in consultation with Mapping & Registry RHDHV Sitech Site Office.
11. Work to be carried out in pits and trenches
 Specific activities other than excavation work, such as laying, replacing, repairing, etc.
of pipelines, cables, sewers and other installation parts, shall be subject to the
applicable work permits and technical specifications/standards.
12. Confined space or special space
 The work permit shall specify whether the pit or trench is to be considered a confined
space or special space. For further information see the chapter on work permits of the
Site Rules.
13. Acceptance Committee OBL
 Where site users use OBL pipe racks, sewers, underground routes and roads for their
piping, cables and other installation components, they must report proposed installation
or modification of such piping, cables and other installation components to Mapping &
Registry RHDHV - Sitech Site Office for discussion by the Acceptance Committee
OBL. Implementation may commence only following approval by the Acceptance
Committee OBL.
December 2015