Technical map of the Weser-Ems administrative area marking Oldenburg for explosive ordnance assessment and surveying by FONTANA-EOD

Explosive ordnance surveying and disposal in Osnabrück

For project owners, planners and site management in Osnabrück, FONTANA-EOD coordinates explosive ordnance assessment with the earthworks sequence. Preliminary ground interventions for access roads, temporary installations or site setup are considered together with the main excavation and connections. Send the site plan, intervention depths, construction sequence and existing investigation results for specialist coordination.

Preliminary work

Include early ground interventions too.

Construction phases

Schedule surveys before the respective earthworks.

Handover

Make results available before the next ground intervention.

Discuss the construction sequence with usExplosive ordnance assessment in Lower Saxony
Assess the construction project

When an explosive ordnance assessment becomes relevant to your project

The City of Osnabrück distinguishes aerial photograph assessment from investigation of the construction area; the type and scope of surveying depend on the planned measure. Bring together the affected construction section, planned earthworks and their depths with existing reports. A local project reference of our own is the specialist explosive ordnance supervision during construction on Bessemerstraße. Our service page explains how we provide specialist supervision of groundworks. The conclusions of the reference commission apply only to its agreed investigation scope.

Project references

Selected project examples

Project site

Connect the site with the specific construction task

Illustration of a map with the Lower Saxony coat of arms, a tablet, hard hat and documents.

Site and existing requirements

Specify the actual project location with a site plan and the affected land parcels. Existing information, official conditions and reports are assigned to this area. Osnabrück is in Lower Saxony in the Weser-Ems administrative area. The City of Osnabrück is responsible for explosive ordnance hazard response within the city; information and existing reports are assigned to the specific property and ground intervention. For addresses in the city centre and old town, Schinkel, Wüste, Westerberg, Sutthausen, Dodesheide or Hellern, identify the available documents. For enquiries from Belm, Wallenhorst, Hasbergen, Georgsmarienhütte, Lengerich or the Osnabrück district, provide the complete project address with municipality and federal state. The competent authority is clarified for the actual project location.

Explosive ordnance assessment in Lower Saxony
Local context

The investigation must fit the actual construction sequence

Local starting point

The City of Osnabrück’s guidance on explosive ordnance surveying explicitly addresses ground interventions during construction. It distinguishes aerial photograph assessment from investigation of the construction area and states that the type and scope of surveying depend on the proposed measure. An assessment alone is not described there as explosive ordnance clearance for the construction area.

The City of Osnabrück documents the severe bomb hit on the town hall on 13 September 1944. Reconstruction began in 1947 and was completed in 1948. When preparing ground interventions in the historic city centre, the buildings and recorded destruction at that time are compared with later construction conditions. Former basements, excavations and subsequent fill are assigned to present-day intervention areas insofar as files and plans identify them. The position and depth of the work actually planned are decisive.

Implications for construction planning

When preparing construction, also describe work taking place before excavation for the building. If a temporary access road is planned first, followed by service works and then a deep excavation, the areas and depths of each stage are recorded separately. For later tasks, it is checked whether the available results cover the respective intervention. For properties around the station, railway or linear infrastructure sites and transport routes, former construction and land-use phases are compared with the present-day intervention. This also applies to records of older production and storage sites, commercial and industrial sites whose use has changed repeatedly, housing and conversion sites. Information on reconstruction, relocated rubble or terrain changes is spatially assigned to the areas affected.

Working together

Distinguish the tasks of client, designers and specialist contractor

Client and operator

The client describes the project and provides the available project records. The operator adds requirements for use, access and timing. A coordinating contact brings the parties together; individual tasks remain assigned to the named parties. Before commissioning, it is clearly recorded what information is missing, who will obtain it and what decision the result is intended to prepare.

Planning and construction management

The specialist designers describe areas, depths, construction methods and changes. Site management coordinates the planned sequence with the construction contractors and agreed specialist works. Results are assigned to the respective intervention. A technical plan change is communicated early enough for its effect on the survey task to be assessed before construction. Organisational construction stage boundaries remain distinguishable from technical survey boundaries.

Specialist company and competent bodies

The private explosive ordnance specialist contractor performs the agreed investigation and documentation work. Official requirements and decisions are clarified with the respective responsible bodies. The records needed for a specific procedure depend on the location and project. The technical report documents the specialist work carried out and its area, depth and limits of conclusions. The responsible bodies make official decisions concerning subsequent groundworks.

The City of Osnabrück is the local hazard response authority. If explosive ordnance is found, it organises the necessary measures, such as clearing the area and evacuation. Lower Saxony’s explosive ordnance disposal service supports the municipality and carries out its assigned recovery and disposal tasks. Commercial specialist companies carry out commissioned hazard investigations. Contacts, official conditions, reporting channels and the handover of assessed findings are agreed before the affected work.

Investigation task

Which specialist task comes next?

First assess the existing findings

Aerial photograph analyses, official correspondence and earlier technical reports are related to the current project. What matters is which question each document answers and which spatial area it covers. Analysis of historical imagery must be distinguished from technical investigation of the present ground. If findings are missing or do not match the planned construction task, the further investigation needed is agreed with the specialists.

Assess historical documents

Relate the investigation to the area and depth

For the technical investigation, a suitable method is selected according to the objective, depth, ground and interference. A standard device alone does not define an appropriate service. The agreed scope identifies accessible areas and required results documentation. Even for a partial investigation, it must remain clear which area is actually investigated and which questions still require clarification afterwards.

Prepare the survey with the specialists
Project types

Identify preliminary interventions in Osnabrück in good time

Illustration: two people review plans and documents at a table beside a construction vehicle.

Site setup before the main excavation

An investigation is often requested for the later excavation. However, site fence foundations, temporary services, drainage or an access road may disturb the ground beforehand. Describe these tasks with the same spatial care as the main excavation. The first necessary investigation date depends on the first affected intervention. A later excavation appointment does not automatically cover this preparation.

The site setup plan identifies the individual preliminary tasks and shows the ground volumes they are intended to affect. For each area, it includes the planned depth, required working space and intended execution date. The enquiry also shows which areas are already accessible for investigation. Temporary and permanent installations remain distinguishable on the plan. The specialist planners can use this to identify which investigation results are needed for the first tasks and what belongs to the later main excavation. If, for example, a temporary service alignment or access road position changes, the specialist company receives the new plan before the affected work is carried out.

Coordinate the sequence and tasks
Illustration: two people with a tablet beside a drawing table and a survey trolley on a construction site.

Service works under several commissions

Utilities, drainage and road opening may be carried out by different companies. For explosive ordnance assessment, the actual trenches, chambers and working volumes are recorded together. Handovers between companies must not create undescribed gaps. Site management needs the associated report and unresolved matters for each section. A general note about the overall project is too imprecise.

Where two service sections cross, both alignments are compared with their respective depths and working space. A chamber or connection may form a different spatial task from the continuous trench. The shared site plan shows these transitions even if they belong to different commissions. Each contractor can identify the documents relating to its work area. If construction lot identifiers and report areas do not match, their correspondence is clarified before handover. Changes to a connection are then also communicated to participants whose work areas are affected.

Specialist services and investigation tasks
Illustration: a person wearing a hard hat and holding a tablet beside a cordoned-off excavation with an excavator.

Demolition followed by deeper new construction

When replacing a building, demolition work on foundations may already constitute ground interventions. Deeper new foundations may follow. The two phases are described separately in the task definition. Existing structures may also limit investigation. Whether preliminary specialist work or work during construction is suitable is decided from actual accessibility and the investigation objective.

Floor plans and existing information on basements, foundations and underground connections help identify the individual interventions. The planned condition after demolition is compared with the later new building and its foundation depths. For each phase, the specialist planners define the investigation task and prerequisites for execution. For an area initially inaccessible, it is documented in which construction condition it is to be investigated. After existing structures change, it is checked which assumptions still apply. New findings are passed on with the previous results documents, allowing the following commission to build on the status actually achieved.

Provide specialist supervision of excavation
Preparation

Prepare the scope and commission together

Establish what needs to be known before commissioning the work

First establish which decision the commission needs to support. Is the task an initial assessment of existing documents, an investigation of a specific area or examination of an anomaly that has already been assessed? These tasks require different evidence. A general wish for safety does not define an investigation that can be carried out. The enquiry therefore specifies the groundworks, location, depth and available findings. Suitable specialist work and the required reporting are then agreed on that basis.

Define the specialist task

Coordinate preparatory work with the investigation

Required access and survey conditions are clarified before the site visit. This may include keeping areas clear, obtaining service information and coordinating with other trades. The method and site determine which preparations are actually needed. Changes to the surface or additional groundworks are not undertaken unilaterally simply to prepare for a survey. Their sequence is agreed with the specialist designers and responsible parties.

Clarify preparatory work in the programme

Agree a clear scope and schedule

A reliable process distinguishes work already technically clarified from prerequisites still unresolved. If an area will only be partly accessible, this must be taken into account when commissioning the work. Handover and assessment of results also need time in the construction programme. Specific coordination connects the described scope with access, records, execution conditions and the date by which a decision is needed.

Discuss the scope and schedule
Earthworks during individual construction phases

Which interventions occur before and after the main excavation?

01

Site setup involving ground interventions

A site access road is not automatically mere use of the surface. If paving must be removed, temporary services installed or foundations constructed, for example, these interventions form part of preparation. Show the work actually planned on the site plan; the name “site setup” does not establish investigation needs.

02

Excavation and deeper structures

Alongside excavation across the area, deeper sections for chambers or foundation elements may be added. Record their position and depth separately so that the investigation can take these differences into account. If the foundation design changes, compare before execution whether the existing investigation result still covers the new intervention.

03

Road and service connections

For a connection outside the main excavation, different documents, installations and access conditions may be relevant. The connection to the existing network should therefore be described as a separate work area. Existing service plans and traffic constraints support coordination; they do not themselves demonstrate an explosive ordnance investigation.

04

When another company continues the work

If another company undertakes further earthworks after the civil engineering stage, it must receive the results relevant to its work area. Hand over the associated report with the current plan version, investigation boundaries and unresolved matters. An oral statement that an area has already been investigated is insufficient.

Project documents

Documents that establish the next step

Sequence of the first earthworks

Provide a sequence starting with the preliminary work. Alongside the main excavation, record boreholes, services and temporary installations planned earlier. The area and depth intended for each task should be clear. This identifies when the specialist findings needed must be available.

Provide complete requirements to those carrying out the work

Official correspondence and specialist reports are passed on with their appendices to the respective affected parties. An isolated sentence may omit the spatial scope or a condition. Site management assigns the documents to the construction plan. Changes are referred back to the specialist planners before the affected work.

Construction sequence

Coordinate investigation and construction sections

Preparatory investigation and initial ground works

The sequence is planned around the ground works actually proposed. Drilling, service diversions or temporary foundations may already be planned before the main excavation. For each affected area, it is clarified what must be established beforehand and which records are available. Construction plans already submitted may need additional construction details later. These additions are submitted for specialist assessment before the work concerned begins.

Coordinate the construction phase with us

Further construction phases and changed plans

At the transition to the next construction phase, it is checked which results still apply. The location, depth and limitations described in the report are decisive. Additional working areas or changed methods are explicitly included. An interim release of an area for operational use and the technical findings of an investigation report are different matters. Site management receives the clarified status together with the associated plans and outstanding next steps.

Coordinate the construction phase with us
Method selection

Select methods according to the task and survey conditions

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

Electromagnetic investigations may be suitable for certain metallic target objects and site conditions. Suitability is justified for the particular task, rather than inferred from equipment availability alone. Interfering installations, accessible areas and the conclusion required must also be considered. Results are documented with their location and investigation conditions. Whether a supplementary method is needed follows from the technical assessment and remains a specific project decision. TDEM records time-dependent electromagnetic responses from electrically conductive objects.

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 investigation task affect interpretation. An anomaly is not automatically explosive ordnance, and an area without anomalies is not general evidence for arbitrary depths. The technical interpretation and limitations are documented with the commission. An investigation for other purposes is not adopted as explosive ordnance evidence without assessment. Highly conductive ground can limit its range.

GPR and limitations

Deep-ground and downhole surveys

For deeper groundworks, it may be necessary to establish whether a surface investigation can provide the required findings or another approach is needed. Preparation includes the location, depth, borehole layout and existing services. Creating access for the investigation must also be properly planned by specialists. A general depth figure or standard grid cannot replace that work. Findings remain limited to the areas actually investigated and the method used.

Prepare deep interventions

Survey during construction

If a necessary preliminary investigation cannot be completed, it is assessed whether a technically planned approach during construction is suitable. This includes coordinated investigation, interpretation and communication of findings within the planned workflow. Visual observation during excavation is not an interchangeable substitute for a necessary survey. Site management needs a clear description of when specialist work takes place, how new findings are handled and which areas remain unresolved. Where the method is suitable, each working layer is technically surveyed and assessed before controlled removal in layers. Visual checks supplement the survey. The process continues to the agreed excavation base and, where necessary, along walls or slopes; the stop signal, authority to issue instructions and reporting channels are agreed beforehand.

Agree the approach during construction
Investigation before and during excavation

Select methods for the task and construction condition

Clarify the historical evidence before the ground intervention

A historical aerial photograph analysis and existing investigation reports help describe the starting situation. The complete plan appendices form part of this. Any supplementary technical investigation needed is determined from these findings and the planned groundworks. Earlier buildings or previous excavation do not provide general evidence that an area is free from explosive ordnance.

The historical question also covers the preliminary intervention areas outside the later excavation. These work areas are identified on the current plan. Existing assessments are provided with their complete appendices and compared spatially with these areas. Unresolved assignments or missing explanations are recorded as specific enquiries. If the evidence is insufficient for the intended assessment, the scope of supplementary research or aerial photograph analysis required is clarified. Its result enters investigation planning with its spatial reference and limitations. If work areas are added later, the evidence available for this additional task is checked.

Consider areas and depths together

A surface survey must be assessed against the investigation objective and local measurement conditions. Different or supplementary methods may be needed for deeper interventions. The decisive point is whether the planned investigation can provide substantiated findings for the intended work area; a fixed range cannot be promised generally across the city.

The excavation, service trench and individual ground investigation points each receive their own position and depth information with the associated elevation reference. The specialist company compares this information with local conditions and explains a suitable approach. A changed formation level or additional deeper section is described with its new spatial scope. Results documentation likewise relates to the areas actually investigated. Later comparison with construction can therefore identify which question was investigated and which additional volume of ground needs assessment when plans change.

Prepare surveying during construction

If ordnance surveying during construction is required, investigation and earthworks must be coordinated by specialists. The DGUV distinguishes this task from visual observation during excavation alone. The method, necessary personnel and protective measures must be defined before the excavator appointment.

The schedule links the respective investigation tasks with the planned construction sections. Participants agree which areas must be available, which preliminary work is necessary and who supplies the associated information. For site management, the results documents needed before the next affected task are recorded. If only part of a section is investigated, the status achieved and remaining tasks are described spatially. Further execution is coordinated with this status. Following changes to the construction sequence, excavation geometry or accessibility, coordination is updated before the next affected intervention; the companies involved receive the relevant plan and report versions.

Next steps

What needs clarification before the next construction phase

01

Record the work sequence

Record preliminary work, the main excavation and connections with their areas and depths.

02

Assign reports to construction sections

Assign existing assessments and reports to the respective work areas. If historical questions about individual areas remain unresolved, supplementary land-use records are researched and suitable wartime aerial photographs assessed, where available. The findings and assessment limitations are assigned to the present-day construction sections.

03

Agree the investigation

Before each groundworks task, clarify which investigation is necessary and under what conditions it can take place. A suitable method is selected according to the investigation objective, depth required, ground conditions, services, sources of interference and accessibility. This selection explains the specialist work and preliminary tasks needed for each construction section.

04

Investigate the agreed area

The specialist contractor carries out the commissioned investigation. Survey grids, necessary borehole locations and access for investigation are coordinated with the area, level reference, ground works depth and local conditions. Survey data and findings are spatially referenced; inaccessible sections and interference are recorded.

05

Assess findings and agree further work

The results are compared with the construction task. Anomalies, assessed findings and unresolved areas are identified separately. For confirmed explosive ordnance, recovery and further handling are agreed with the responsible bodies in accordance with the division of responsibilities in Lower Saxony.

06

Hand over results

Hand over the report with its associated plans to site management and the contractors.

Documentation

Hand over investigation reports before earthworks

Findings and their scope

A suitable results report describes the area investigated, methods used and limitations of their conclusions. Areas or depths not covered remain identifiable. For investigation in stages, record which document applies to which construction condition and who arranges any necessary supplement. This prevents an older plan from silently remaining the basis of later work.

Project responsibilities

Commissioned technical work must be distinguished from statutory hazard response. In Lower Saxony, this is the responsibility of municipalities; the state explosive ordnance disposal service supports them and carries out its assigned recovery and disposal tasks. The private investigation documents the commissioned technical scope. Official decisions are made by the competent authorities; project participants coordinate further work accordingly.

Working approach

How FONTANA-EOD works

Document the agreed specialist service clearly

We assess the planned groundworks against the available documents and their design revision. Before attending site, we agree with you what needs to be investigated, which areas are accessible and what findings are required. If the design or site conditions change, we check whether the agreed scope remains appropriate. The report states what was actually investigated and the limits of the findings. This allows designers and site management to see which findings they can use and where questions remain.

Discuss the investigation task

The task before the equipment

We first establish the investigation objective: which question must it answer? We then select a technically suitable method. The availability of a particular device or experience on a similar neighbouring site is not enough to justify the choice of method on its own.

Keep limitations visible

Inaccessible areas and limited conclusions are identified. They do not disappear into a total area figure. Designers and site management can then decide specifically which areas still need attention and when a suitable survey becomes possible.

Clarify changes before intervening in the ground

A new location, additional depth or different construction method is compared with previous results. A familiar project name does not replace this comparison. Feedback is provided before the affected work so that an outstanding question can be included in the sequence.

Hand over the report and plan together

The technical conclusion remains connected to its location references and appendices. A brief summary helps orientation but does not replace the documented survey scope. This basis is retained even if site management or contractors change.

Understand the results

Use technical statements for the next decision

Read results together with their scope

A statement is understandable only with its investigation task. Check the area and depth described, methods used and restrictions. A report title or single result line is insufficient. For new work, these details are compared with the current plan to establish which knowledge remains usable and which question is unresolved.

Explore results and terminology

Use project terminology unambiguously

Document review, surveying, construction-phase specialist work and recovery are different tasks. An enquiry need not identify the correct method in advance. An accurate description of the intervention and required decision is more useful. This establishes the appropriate technical scope and prevents a general term from meaning different things in design, procurement and execution.

Understand the service scope
Design and findings

Documents for the next construction decision

Illustration: aerial photographs and maps on two screens and printed on a desk.

Historical evidence and the current design

Aerial photograph interpretation is related to the actual groundworks. Its purpose and geographical scope remain distinct from a technical investigation of the ground as it is today.

Understand aerial photograph assessment
Illustration: two people review plans and documents at a table beside a construction vehicle.

Specialist reports for site management

The findings, their locations and limitations are handed over together. This makes clear to those carrying out the work which area has been investigated and which task remains outstanding.

Assess investigation reports
Four people in orange high-visibility vests in front of two excavators on a construction site.
Person with a yellow survey cart on a footpath in front of a hedge.
Questions from planning

Questions about construction preparation in Osnabrück

When should explosive ordnance assessment be included in the construction sequence?

As soon as the first ground interventions are specifically planned. These may already include geotechnical investigation points, temporary connections or preliminary earthworks. The necessary investigations must be coordinated with these tasks, rather than only with the start of the main excavation.

Is an aerial photograph assessment sufficient to start construction in Osnabrück?

The city explicitly states that an aerial photograph assessment does not provide explosive ordnance clearance for the construction area. Whether a technical investigation is needed, and which type, must be clarified using the findings and proposed measure. This question must be clarified from the specific documents before your construction starts.

Can several construction sections be investigated in sequence?

Whether investigation in stages is suitable must be assessed against the design. The limits of each result, earthworks sequence and unresolved areas must be recorded. The construction schedule alone does not justify work in a section not yet sufficiently assessed.

Which documents does the contractor need for the next excavation?

The investigation results relevant to its area and depth, including plan appendices, limitations and any necessary follow-up measures. Also check whether the report handed over matches the current construction plan. Evidence from another construction phase cannot be applied without comparison.

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

If possible explosive ordnance is found, stop work at the location immediately. Do not touch, move or expose the object further. Leave the immediate area, keep your distance and keep others away without putting yourself at risk. In Germany, notify the police immediately on 110 and follow their instructions. Inform site management and the client; internal reporting must not delay the emergency call. An enquiry form for planned construction projects is not an emergency reporting channel.

Why does a temporary service form part of construction preparation?

Because its trench may disturb the ground before the main structure is built. Where investigation is needed, this first intervention must be included in planning. Describe the position, depth and working space of the temporary installation, together with its planned construction date.

Which factors determine the investigation scope and costs?

Area, intervention depth, available documents, ground conditions, metal interference and access determine the investigation task. Required preparation, interpretation, assessment of findings and documentation must also be considered. When agreeing the quotation, identify the first interventions, further construction phases and existing results. Unresolved quantities or access are agreed before execution.

How is an area cleared of obstructions later addressed?

It is compared with the previous investigation scope. If it was previously inaccessible or its measurements could be interpreted only with limitations, that limitation remains until specialist clarification. Further work is coordinated in good time before groundworks start there.

Project enquiry

Discuss the sequence of your groundworks

Plan revision and decision deadline

State whether the enquiry concerns early planning, preparation for tendering or ground works about to begin. The date by which technical findings are needed helps coordination. Outstanding information is explicitly identified rather than replaced with assumed values. Specify the earliest ground works, construction time windows, maximum ground works depths and investigations already commissioned.

Assign records to their locations

Send a site plan and available reports with their associated appendices. For several construction phases, identify which document belongs to which area. Photographs supplement descriptions of access and existing structures; they do not replace information about underground structures or planned depths. Include official correspondence, conditions, service plans and ground investigation records or records of existing structures. Identify contacts and areas that are not yet accessible.

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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