Person wearing a hard hat beside a vehicle on a marked-out construction area in front of a cooling tower and industrial installations.

Explosive ordnance assessment at substations and energy installations

For a new cable trench or foundation in an existing substation, the working area and operating conditions must be defined. FONTANA-EOD clarifies the investigation needed in the ground with your design team. The operator and responsible electrical specialists determine which electrical protective measures and operational permissions the work requires. These requirements inform preparation of the explosive ordnance investigation.

Working area

Show the location and depth of the groundworks on the plan.

Installation operation

Clarify protective measures with those responsible.

Survey feasibility

Identify utilities and metal installations.

Critical infrastructure

Discuss groundworks within the installationSelect suitable investigation services
Context

Review permission to work and the explosive ordnance report separately

Operational permission to work and the explosive ordnance investigation are documented for each section according to their different purposes. The responsible electrical specialists clarify the installation's electrical state; the explosive ordnance report describes the investigation carried out on the ground. Describe the planned groundworks and provide existing explosive ordnance reports accordingly. Also state which operational prerequisites have already been clarified.

Project references

Selected project examples

Investigation task

Define the ground disturbance within the energy installation

Two people with a tablet beside a marked construction area; plans lie in the foreground.

Describe the volume of ground affected for the investigation

An extension to an energy installation may involve foundations, cable trenches, drainage and temporary working space. Show the location, depth and reference level of these areas of ground disturbance. FONTANA-EOD can then relate available evidence to the work actually planned. Calling a project an alteration or maintenance does not, by itself, define an investigation scope. Even a small technical addition may affect ground previously assessed for a different purpose.

Select services according to the actual volume of ground affected
Two people with a tablet beside a marked construction area; plans lie in the foreground.

Account for existing structures when selecting methods

Utilities, metal installations, foundations and adjacent equipment can affect preparation of an investigation. Add available as-built plans and identify known uncertainties. The technically appropriate approach depends on the task and accessible conditions. Shutdown does not automatically mean that every technical investigation is possible without restriction. Construction conditions, access and remaining structures are still considered for the specific area.

Coordinate methods with existing structures and access
Two people discussing plans at a table beside a vehicle on a construction site.

Compare the earlier investigation with the new depth

Read an earlier report together with its site plans and described task. For a deeper foundation or altered cable route, check whether the earlier findings remain applicable. The actual limits of the specialist work are decisive. An already investigated installation site does not provide blanket coverage for all later depths and extensions. The new construction design therefore remains the basis of the technical comparison.

Compare investigation scope with new depths
Project types

Distinguish individual construction tasks within an existing installation

Person in high-visibility clothing beside a utility trench, with solar panels and wind turbines in the background.

Cable trenches and connection points

Describe the route, connection pits and local deeper excavations together. Even a short new connection between existing foundations may affect ground not previously addressed. Utility information from the responsible bodies is brought together with the construction plan. Clarification of existing utilities is handled by the bodies responsible for utility information. Both sets of information are needed during preparation so that the agreed specialist work can be related to the actual ground disturbance and local conditions.

Assess connection pits and cable routes
Two people with a tablet beside a marked construction area; plans lie in the foreground.

Foundations for technical equipment

For a new unit, cabinet or load-bearing component, specify the foundation, excavation and required working space. The visible installation footprint may be smaller than the area of ground affected. Additional sections show differing depths. Existing documentation for an adjacent route is used only after a spatial and technical comparison. This makes clear which findings already apply and which additional question needs addressing.

Clarify the investigation scope for installation foundations
Two people with a tablet beside a marked construction area; plans lie in the foreground.

Drainage and ancillary installations

Chambers, channels and connections may reach different depths from the rest of the works. Mark them on the plan even if they belong to a separate trade. A general description of the installation area should not obscure these local areas of ground disturbance. Preparation distinguishes dismantling, construction and connection. The specialist findings can then be related to the groundworks actually planned.

Select methods for drainage and ancillary installations
Project enquiry for ordnance assessment and surveys.

Access routes and temporary working areas

Equipment setup or construction logistics may require additional areas. Describe whether ground will be removed, surfaced or anchored for this purpose. Use as a temporary working area does not, by itself, determine investigation requirements. The actual construction activity is decisive. Access and bearing capacity are clarified by the responsible parties and coordinated organisationally with the requirements of the agreed explosive ordnance specialist work.

Coordinate temporary areas and access
Prepare the decision

Base initial coordination on the specific alteration

Structures and depth

Show new trenches, foundations and connections on a current plan. Add the actual working depths and reference levels. Investigation requirements can then be derived from the construction activity rather than a general description of the entire installation.

Existing structures and access

Provide as-built documentation and the intended working area. Name known uncertainties. The operator explains the organisational prerequisites so that the specialist contractor can relate its task to the conditions actually accessible.

Timing and responsibilities

Name the planned construction phases and contacts for operational and construction questions. Keep provisional details clearly identified as such. The specialist scope required is then compared with the available working windows.

Project-specific tasks

Clarify the working area and installation operation before deployment

01

What groundworks are planned?

Describe, for example, a new cable trench, alteration of a foundation or addition to an earthing system as separate areas of ground disturbance. Location, extent and depth are required. Mark the specific trenches, excavations or foundation points on the installation plan.

02

What electrical equipment remains in operation?

Ask the responsible operator representatives to specify the operating conditions relevant to the work. These include the boundaries of the accessible area and required protective measures. The design team and specialist contractor need the conditions applicable to their assignment. Technical switching operations remain with the responsible electrical specialists.

03

When can the area be accessed?

An available time window must also provide a usable working space. Clarify access, traffic routes and planned equipment and material positions. State which zones become accessible only after an operational change. The investigation can then be planned in the appropriate sequence.

Project documents

Bring together documentation for the investigation

Current construction design

The ground disturbance plan shows spatial boundaries and differing depths. Additional working space and temporary construction conditions are described too. This gives specialist planning a traceable basis for the specific task.

Existing specialist reports

Provide reports with their attachments and the plan revision to which they originally relate. Keep limitations visible. Only the combined comparison establishes which findings can be used for the current works and which questions remain open.

Operational information

The responsible bodies provide the conditions relevant to the planned working area. Changes follow a clear reporting route. The specialist contractor coordinates its activity using this information; operational decisions remain with those responsible for them.

Documentation

Document investigated areas on the installation plan

Identify the survey scope

The specialist report must show which areas were investigated and what the results mean for the agreed assignment. Location references, areas addressed and limitations are decisive for later use. For new groundworks, check whether they fall within the documented investigation scope. Belonging to the same installation is insufficient. Assign necessary follow-up investigations or exposure work to the affected area. Recovery of confirmed explosive ordnance is coordinated with the permitted scope of activities, local responsibilities and documentation requirements. Following actual exposure or clearance work, include the corresponding findings and clearance records.

Coordinating further work

Operational permissions and electrical requirements remain identifiable as separate documents. Agree which documents construction management needs for each section and who provides them. Security of supply and other operator obligations are clarified separately with the responsible operations staff and specialists.

Technical assessment

Technical foundations: BFR KMR: Clearance planning and clearance concept – introduction · BFR KMR: Geophysics · BFR KMR: Documentation · DGUV Information 203-001: Safety when working on electrical installations · § 5 ArbSchG: risk assessment · § 8 ArbSchG: cooperation between employers

The Federal Guidelines on Explosive Ordnance Clearance contain requirements for historical and technical investigation, clearance concepts, procurement and documentation within their defined federal remit. Their application to the specific construction project at the energy installation, together with locally applicable requirements and responsibilities, is clarified separately.

Next steps

Coordinate investigation with installation plans and operating conditions

01

Provide plans and existing reports

Provide the extract of the installation plan relevant to the ground disturbance, existing explosive ordnance reports and the planned construction conditions. Mark unresolved locations. The information on substations and transformer stations is compared with the installation and foundation design.

02

Name the responsible contacts

Assign each open question to a responsible person: installation operations, construction management or the explosive ordnance specialist contractor. Where employees of several employers work at one workplace in Germany, the employers cooperate on occupational safety under § 8 ArbSchG and coordinate the necessary protective measures. The documents must show who issued each specialist assessment or operational permission.

03

Agree the survey method

Existing reports and historical evidence are related to the ground disturbance. Ground conditions, utilities, metal components and accessible areas determine which technical investigation is suitable. Methods, occupational safety and any necessary preparatory work are coordinated with the operator and construction management before work proceeds. Existing information and reports are reviewed for their plan revision, spatial scope and questions still open for the current construction task. If historical evidence is missing, suitable sources are researched and aerial photographs evaluated for the affected installation areas. The results are related to the present-day ground disturbance and used to plan further investigation.

04

Carry out the investigation

The commissioned investigation is performed in the agreed installation areas. Data, findings and restrictions are recorded with position, depth and plan references.

05

Assess results

Survey data and findings are evaluated by specialists. Areas still open, necessary follow-up investigations and the next decision are identified for installation operations, designers and construction management.

06

Check changes before the next construction section

Before the following construction section, check whether the working area and planned groundworks still match the documented position. Pass on open investigation areas and operational restrictions separately. Specify in the next assignment which questions still need clarification before groundworks begin. Assessment, areas addressed and the limits of the findings are documented in the report with the corresponding plan attachments.

Technical assessment

Check survey conditions among utilities and installations

Identify sources of interference in advance

Metal installations, utilities and cables can affect geophysical investigations. As-built plans and information about visible installation components help preparation. Whether a surface survey or another method is suitable for the planned ground disturbance is assessed using the conditions on site. Necessary investigations and protective measures are planned before ground disturbance during vegetation clearance, dismantling, surface breaking or creation of access routes and working areas. Areas becoming accessible later are investigated before the respective subsequent ground disturbance.

Clarify operational permission and survey feasibility separately

Electrical operating conditions and the ability to obtain geophysical findings are different questions. Even after operational permission is granted, existing metal components may limit the investigation. Conversely, a survey method that is suitable in principle does not permit access to an area closed for operational reasons.

Compare changed trenches and excavations with reports

If a cable route is relocated or a deeper excavation planned, compare the new ground disturbance with existing results. Changed working conditions may also require protective measures to be coordinated again. Record which change was assessed and which specialist or operational measures follow from it.

Method selection

Select survey methods for work within an existing installation

Existing utilities, new structures and operational accessibility are considered together. Use as a utility installation does not dictate a single method; the specific investigation task is decisive.

Historical records and aerial photographs

Historical aerial photograph assessment and other old records help place the basis for suspicion in its spatial context. The available images, their evidential value and the limits of the area considered matter. The absence of an identifiable indication must be distinguished from a technically surveyed ground area. The assessment is considered together with the planned intervention and other available findings. It can support the choice of a survey, but is not a measurement of the present-day subsurface or confirmation for all future works.

Understand aerial photograph assessment

Magnetometric survey

Magnetometric methods detect magnetic anomalies. Whether they can address the specific survey task depends, among other things, on the expected objects, ground conditions, interference and required survey area. Fences, utilities or existing structures may affect interpretation. A measurement signal is therefore not described as ordnance solely because of its strength. Method, interpretation and any further investigation are planned as a connected specialist task.

Understand the scope of magnetometry

Electromagnetic methods and TDEM

Electromagnetic surveys may be suitable for particular metallic targets and site conditions. TDEM detects the time-dependent electromagnetic responses of electrically conductive bodies. Suitability is justified for the particular task, not inferred merely from the availability of equipment. Interfering installations, accessible areas and the required conclusion must also be considered. Results are documented with location and survey conditions. Whether a complementary method is needed follows from the specialist assessment and remains a specific project decision.

Understand electromagnetic surveying

Ground-penetrating radar

Under suitable conditions, ground-penetrating radar can provide information about subsurface structures and reflections. Ground conditions, moisture, installations and the particular survey task affect interpretability. An anomaly is not automatically ordnance, and an area with no apparent anomalies is not general evidence for arbitrary depths. The specialist interpretation and its limits are documented with the instruction. A survey for another purpose is not adopted without checking as ordnance evidence.

GPR and limitations

Deep-ground and downhole surveys

For deeper ground interventions, it may be necessary to assess whether surveying from the surface can provide the required assessment or a different approach is needed. For individual foundation or chamber locations, the ground volume to be assessed and achievable survey coverage are compared before a borehole grid is defined. Necessary surveys and protective measures are defined before boreholes are created. Location, depth, borehole arrangement and existing utilities then form part of preparation. Creating survey access must also be planned using a technically suitable approach. A general depth figure or standard grid does not replace this task. Results remain limited to the areas actually addressed and the method used. For surveys from investigation boreholes, casing, drilling depth and documentation are also coordinated with the task and site conditions.

Prepare deep interventions

Survey during construction

If a necessary preliminary survey cannot be completed in full, the suitability of a technically planned approach during construction is assessed. Each working layer is technically surveyed and evaluated before controlled removal in layers with supplementary visual inspection follows. The steps are repeated to the agreed excavation formation. Excavation layers, stop signal, authority to give instructions, reporting channels and documentation are agreed with site management and specialists before work starts. Pure visual observation of the excavation cannot simply replace a necessary instrumental survey. Site management needs a clear description of when specialist works take place, how new findings are handled and which areas remain outstanding.

Agree the approach during construction
Working approach

Specialist work under the agreed installation conditions

Agree the task and prerequisites together

FONTANA-EOD prepares the explosive ordnance specialist work using the planned earthworks, available evidence and specified installation conditions. The agreed scope describes the area and question to be addressed. The responsible bodies provide the operational prerequisites. The report relates the investigation carried out to its areas and depths. Operational permissions are documented separately according to their respective purposes.

Discuss the investigation task

Keep responsible contacts available

The design team explains structures and depths; the operator names contacts for operational conditions. Where several specialists are responsible, record which question goes to whom. Central project coordination can bring the information together; individual decisions remain with the named responsible parties. Questions about access, the working area and changes should be answerable in time for the planned deployment.

Check actual conditions before starting

Preparation is based on a particular plan and the operating conditions supplied with it. Before work proceeds, check whether the agreed working area is actually available. Different installations or changed accessibility may require renewed coordination. The responsible electrical specialists clarify necessary switching measures; the responsible operator representatives clarify operational prerequisites. The specialist investigation scope is adjusted accordingly.

Document open areas clearly

If a section cannot be accessed or addressed to the agreed extent under the available conditions, it remains identifiable in the documents. A shared installation name does not make it part of a completed result. For further planning, describe the open question and necessary prerequisites. Later work can then be prepared specifically without overwriting the previous specialist findings.

Provide results for the next construction activity

Assign the report and plan attachments to the specific construction phase. Construction management then has a basis for comparing the intended work with the documented scope. The responsible bodies provide operational documentation alongside it. Both sets of information matter for construction. A shortened completion notice should not obscure the spatial limits of the explosive ordnance specialist work or requirements still open.

Construction phases

Develop the investigation scope with the installation design

Early extension planning

Where several locations are possible for a new structure, distinguish the options on the plan. Include known depths, connection points and operating conditions. Initial specialist coordination can then establish which evidence already exists and which information is still needed for selection. The final investigation scope is related to the selected construction task. It does not follow solely from the size of the entire installation site.

Coordinate this work step

Preparation for a planned shutdown

Describe an announced shutdown window in terms of the areas actually available and organisational prerequisites. The specialist work possible within it also depends on the investigation objective and local conditions. The parties therefore coordinate the scope needed in advance. Scheduling should also identify which tasks must be clarified before the window and which areas may need separate treatment.

Coordinate this work step

Alterations while neighbouring installation areas remain operational

Where adjacent areas remain in operation, the operator explains the conditions applicable to the working area. The specialist contractor describes the requirements of the planned investigation. A specific sequence is then agreed. If access or operating status changes, reassess the effects on the specialist work that can actually be carried out.

Coordinate this work step

Later alteration of a route or foundation

Compare a subsequently relocated route or deeper planned foundation with the earlier results documentation. Retain the existing report as a record of its scope at the time. The new assessment identifies usable findings and open questions. Even within the same installation fence, an additional area of ground may be affected. Specialist applicability therefore follows the ground disturbance, rather than the familiar site name alone.

Coordinate this work step
Project site

Identify the installation site and local contacts

Illustrated map of Germany with location markers on a construction site.

Show the affected installation on the site plan

State the site, installation and specific construction section. Where several operational units exist, clear internal names and an overview plan are helpful. Add the intended access route and an available project contact. Identifying the region aids preparation. Operator information and the current ground disturbance plan clarify the individual installation's conditions for the activity actually planned.

Identify the project region
Illustrated map of Germany with location markers on a construction site.

Provide existing requirements with their scope

Provide authority information, operator conditions and earlier specialist reports in full. Identify the area and works each addresses. A statement about an earlier cable route may have a different scope from the current foundation. Keep the responsible parties named for queries. Local requirements and specialist findings can then be brought together without confusing their respective subjects.

Identify the project region
Understand the results

Keep operational and specialist statements distinct

Specify the installation's condition

DGUV Information 203-001 addresses protective measures for work on and near electrical installations. The risk assessment and working boundaries defined by specialists govern the specific activity. Necessary electrical measures and responsibilities are clarified with the operator. These tasks remain with those responsible for them even when an explosive ordnance investigation is commissioned.

The responsible bodies provide information about operating status. Preparation requires clarity about the area and period to which it applies. The explosive ordnance specialist work is planned under these conditions. Its documentation then describes the investigation actually carried out. Operating status and explosive ordnance investigation status are documented with their respective areas, time references and limits.

Explore results and terminology

Consider an area together with its depth

An investigated area is considered together with its documented depths, boundaries and limitations. Lateral position may be decisive for a later cable trench, and depth for a new foundation. Keep the corresponding report and attachments together. A general note about an earlier contract is insufficient to establish reliably the scope applicable to changed groundworks.

Document areas and depths together

Determine the appropriate service from the construction question

First describe the planned work and the specialist conclusion it requires. Existing documents may affect the further scope needed. The services overview explains different preparation, investigation and supervision activities. FONTANA-EOD relates their selection to the specific installation. Naming a single device replaces neither a description of the volume of ground affected nor clarification of the actual working conditions.

Select appropriate specialist services
Working together

Name the parties and their tasks

Installation operator

The operator identifies operational prerequisites and responsibilities. The information relates to the specific working area and period. Preparation of the investigation can then be based on actual conditions.

Construction planning

The design describes the planned groundworks and updates the plan revision when changes occur. Short connection sections and local deeper excavations also remain identifiable. They may be decisive when relating existing investigation results to the works.

Specialist company and competent bodies

The specialist contractor addresses the explosive ordnance question within the agreed scope and documents the work carried out. Results remain assigned to the respective ground disturbance. The bodies responsible for other installation and operational assessments provide them separately.

In Germany, state ordnance disposal services and locally competent authorities carry out hazard response and find management. Their involvement and public-order or building-control tasks are established for the project location. Outside Germany, local responsibilities apply. Contacts, requirements and reporting are assigned to the specific works.

Documents and execution

Present information about existing conditions clearly

Two monitors displaying aerial photographs and maps; further aerial photograph printouts lie on the desk.

Identifying historical documents

Older plans or aerial photographs may show the site at a different stage of development. Identify known changes and provide the documents with their spatial references. Specialist evaluation relates this information to the current construction task. Earlier use alone does not establish a comprehensive conclusion about all current installation areas or their differing ground disturbance depths.

Explore the historical basis
Two people discussing plans at a table beside a vehicle on a construction site.

Use current photographs as supplementary information

Photographs can illustrate surfacing, access and visible installations. Relate the photographs to the site plan and observe the site's conditions for sharing them. Visible conditions help preparation but do not replace information about underground installations or operating states. The responsible bodies and corresponding as-built documentation clarify this information for the planned activity.

Understand documentation
Two people discussing plans at a table beside a vehicle on a construction site.

Retain results plans in the project records

File documentation so that the area, depth, plan revision and actual scope of specialist work can be traced later. Keep attachments with the report. For new connections or further foundations, compare the documented position with the current construction design. This prevents an earlier partial investigation from being used as a complete assessment of a later extension merely because the site is the same.

Documenting results clearly
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Person with a yellow survey cart on a footpath in front of a hedge.

Technical information

Critical infrastructure: brochure

Work at critical infrastructure requires careful coordination with operations and construction design. The brochure explains preparation, suitable investigations and traceable result documentation.

Download the brochure as a PDF
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Critical infrastructure: brochure – page 1

German · 8 pages

Questions from planning

Questions arising from energy installation operation

Does the whole installation have to be shut down for every survey?

The responsible specialists determine the measures required according to the specific activity and electrical hazards. Working space, equipment movements and operational conditions must be coordinated for this purpose.

Does FONTANA-EOD carry out electrical switching operations?

The responsible electrical specialists plan and arrange switching operations. The explosive ordnance contract describes the investigation of the agreed volume of ground; operational and electrical measures are organised separately with the operator.

Does shutdown automatically allow unrestricted surveying?

No. Metal installation components and utilities can affect geophysical results independently of operational access permission. Survey conditions are therefore assessed separately by specialists.

Does the report also apply to a cable trench relocated later?

The new route and its depth must be compared with the documented scope of investigation. A change within the same operational site is not automatically covered by the earlier investigation.

What should be done if a suspicious object is found during earthworks?

If an unexpected suspicious object is found, stop work in the affected area immediately. Do not touch, move or further expose it. Leave the immediate area, keep your distance and keep others away without putting yourself at risk. In Germany, notify the police immediately on 110; outside Germany, use the local emergency reporting route. The responsible authorities decide the next steps. Inform installation operations, construction management and the client; internal reporting must not delay the emergency call.

What does a planned shutdown window mean?

It is an operational condition. Whether and to what extent the specialist work can be carried out within it also depends on the investigation objective, access and existing site conditions. These points are coordinated together in advance.

Should additional working space beside the foundation be specified?

Yes, where creating it involves ground disturbance. The visible installation footprint alone may be smaller than the area actually affected. The ground disturbance plan should therefore also show working space and connection points.

What determines the cost of an investigation at an energy installation?

Costs depend on the area, depth and volume of ground disturbance, ground conditions, existing utilities and metal sources of interference, available evidence and the suitable method. Available working areas, operational requirements and agreed shutdown windows influence the work. The quotation relates to the investigation required for the construction section, including evaluation and documentation.

Project enquiry

Provide the installation plan and planned groundworks

Installation plan and ground disturbance

Send the extract of the installation plan relevant to the ground disturbance, showing the type, location, extent, depths and reference levels of the planned groundworks. Add existing explosive ordnance documentation and complete reports with attachments, together with the planned construction conditions.

Operator contact and operating conditions

Name the responsible operator contact, available working areas, access arrangements and construction periods. Add known access restrictions and the status of operational coordination. We will discuss the investigation scope for the planned areas and depths. Switching operations, electrical protective measures and continued operation are coordinated separately with the operator and responsible electrical specialists.

Project enquiry

Have your project assessed

Whether historical aerial photograph analysis, explosive ordnance surveying, surface surveying using GPR, magnetometry or TDEM, deep-ground surveys, downhole surveys, excavation supervision, area clearance or ordnance recovery is needed depends on the location, ground disturbance, depth, ground and existing documents. An early ordnance assessment provides clarity for tendering, programming, occupational safety and construction.

FONTANA-EOD combines its Section 7 SprengG licence, specialists holding Section 20 SprengG certificates of competence, suitable survey and clearance methods, and traceable documentation. Send the site plan, depth of ground disturbance, construction phase and existing documents for an initial technical assessment.

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