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

Explosive ordnance surveying in Langenhagen

If several explosive ordnance reports exist for your construction project in Langenhagen, their respective scope must be clear before groundworks start. Which individual areas have been investigated, and which recommendations remain outstanding? FONTANA-EOD clarifies further investigation needs with you and carries out the commissioned investigations and their documentation.

Assign findings to their areas

Assign reports to the areas investigated.

Completed or still outstanding?

Distinguish recommended investigations from those carried out.

Plan the next steps

Agree outstanding tasks before ground disturbance.

Discuss the project's technical requirementsExplosive ordnance assessment in Lower Saxony
Assess the construction project

Clearly assign individual areas and investigation results

Several reports for one project may concern different areas, measures and unresolved questions. For your project in Langenhagen, we relate the existing results to the current construction design. Recommendations, investigations actually carried out and unresolved areas remain separately identifiable.

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. Langenhagen belongs to the Hannover Region in Lower Saxony. The region lies in the Leine-Weser administrative area. For the local administrative route, the specific project address is assigned to the relevant municipality. For each site plan, identify the available document version and the authority responsible for the project location.

Explosive ordnance assessment in Lower Saxony
Local context

What the individual reports establish for your construction project

Documented planning status

The draft explanatory statement for Langenhagen development plan 714 “Airport West 2”, dated 18 November 2025, lists several result areas from the aerial photograph assessment. Different recommendations are reproduced for individual areas. The draft also describes investigations by another specialist company. These details concern that project and its documented status.

The Langenhagen town chronicle records air raids during the Second World War, particularly in autumn 1943, and the subsequent reconstruction. For present-day ground interventions, these historical spatial references are compared with later uses, buildings and terrain changes. Each finding is assigned to the land parcels and groundworks actually affected.

Implications for construction planning

For your construction design, the statement “the area was checked” is insufficient. Check which part each report covers, what was investigated and what work was actually carried out. An aerial photograph assessment result must be distinguished from a report on a technical investigation or a recommendation still outstanding.

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.

Within Langenhagen, municipal requirements are agreed with the competent city authority. For a project address outside the city, the respective municipality is responsible. The state explosive ordnance disposal service supports municipalities in Lower Saxony within its remit.

Investigation task

Which specialist task comes next?

Check the questions addressed by the existing documents

Historical aerial photograph analysis and a technical investigation may answer different questions. The first step is therefore to clarify what each result relates to and which limitations are explicitly stated. Simply showing an area without indications does not automatically answer every explosive ordnance question. The complete report, the basis of its investigation and the intended use of the result are decisive.

Assess historical documents

Describe outstanding measures as a defined commission

The new commission identifies the areas and questions not sufficiently covered by existing results. Suitable methods are determined from the objective, depth and actual conditions. Work already completed remains identifiable. This avoids either repeating an old recommendation without checking it or overlooking an unresolved area because of a different partial report.

Compare investigation methods
Project types

Handling different results within one project

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

Several results maps for one property

A larger project may be described by several maps and reports. Their individual results need not contain the same recommendation. Assign the complete records and their status to each area. Where maps meet or overlap, check the spatial relationship. An overall project name must not obscure differing conclusions or turn an unresolved area into one already investigated.

Where maps overlap, compare the reference points, area identifiers and underlying plan versions. A newer report may cover a smaller area than an older one. Record which conclusion continues to be used for each affected area and which enquiry to the respective author is necessary. Site management receives the complete records, including the associated maps.

Document findings and their limitations
Illustration: two people review plans and documents at a table beside a construction vehicle.

Later investigations following a recommendation

An older document may recommend an investigation while a later report documents work already carried out. Both belong in the register but serve different purposes. Check which measure was actually undertaken, which area it concerned and which limitations remain. A reference in a planning explanatory statement may draw attention to a report; construction preparation requires its complete version.

For further commissioning, the scope actually carried out is taken from the report. This includes the depth investigated, methods used and remaining limitations. Official requirements are assigned with their date, full wording and appendices. If a document refers to another final report, that report is requested. Until it has been checked, it remains clear which conclusion is not yet sufficiently substantiated.

Document findings and their limitations
Illustration: two people with a tablet beside a drawing table and a survey trolley on a construction site.

New groundworks between areas already investigated

An additional connection or working volume may lie outside the areas already investigated. Show the new design together with the documented investigation boundaries. The planned depths must also be comparable. Existing findings are used insofar as they suit the task. Specialists determine the remaining needs for gaps not covered or additional ground interventions.

If a borehole is relocated, specify the new starting point, planned drilling depth and elevation reference. For an excavation, working space and necessary connections also count. If the depth references of several reports differ, clarify the comparison using the associated ground elevations. The new investigation commission then describes the volume of ground still unresolved, even if several areas previously treated separately need to be considered together.

Specialist services and investigation tasks
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.

For tendering, work already carried out, investigations still needed and possible additions are described separately. All companies invited to quote receive the same plan version and the same existing results. Specify the expected report contents, plans and handover dates. An investigation merely mentioned remains identifiable as an unresolved documentation matter until complete documentation is available. If changes occur, the agreed scope of work is updated with the affected areas.

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.

Also describe the groundworks necessary to reach an individual area. These may include removing paving, preliminary excavation or creating investigation access. These tasks receive their own position and depth references. Before execution, the responsible parties agree which specialist explosive ordnance prerequisites must be met and how the subsequent investigation will be made possible.

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
Tasks at the site

Record what is available for each individual area

01

Areas assessed

Assign the corresponding area to each assessment. Use recommendations together with the investigation question they describe; do not extend them to neighbouring areas. Where there are several results plans, their respective boundaries and identifiers must remain unambiguous.

02

Areas already investigated

Complete reports and plan appendices are needed for measures carried out. They show which area was actually investigated and which limitations apply. A reference in a planning explanatory statement or meeting minutes may identify such documents but does not replace checking them.

03

Measures still outstanding

A recommendation to investigate does not demonstrate that the investigation was carried out. Unresolved areas, missing reports and necessary enquiries should therefore be identified separately. This makes clear what remains to be done before the next groundworks.

04

New or relocated ground interventions

If an excavation, service or construction site area is relocated, check whether the existing results also apply to the new position. A change may affect several investigated and unresolved areas. Compare the changed design with the respective results plans.

Project documents

Documents that establish the next step

Create a register of the complete records

For each document, record the date, author, reference map and area concerned. Identify whether it is an assessment, a recommendation or a report on work carried out. Missing appendices and unresolved references remain visible. The register provides orientation; the actual conclusions are always read together with their prerequisites and limitations.

Compile the current status for site management

The handover combines the current site plan with the complete specialist reports. Unresolved areas and decisions still needed are identified separately. This shows which findings are available before each ground intervention. For the respective area and plan version, the measurement data, survey results and assessment of findings belonging to the commission are brought together with the complete report. After clearance work has been carried out, the clearance record, including scope, results and limitations, forms part of this handover. An isolated sentence or a colour-coded map alone does not reliably describe the full specialist scope of the records.

Construction sequence

Coordinate investigation and construction sections

Before awarding the next construction section

Compare the planned ground interventions in the next section with all relevant records. This includes reports added later and their appendices. Tender documents must identify which preliminary work actually exists and which tasks are still to be commissioned. Different recommendations are assigned to the respective areas. The sequence follows the specialist findings still needed and the access actually available.

Coordinate the construction phase with us

When the responsible parties change

New site management or another client needs a traceable, current set of documents. The handover includes complete reports, maps, associated correspondence and the register of unresolved matters. Completed work should be identifiable from its supporting documentation. Changes to the construction design are then compared again with investigation boundaries. An oral summary of the project history is insufficient for this spatial assignment.

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 can be suitable for particular metallic targets and site conditions. Their suitability must be explained for the task, rather than inferred simply from the availability of equipment. Interfering installations, accessible areas and the findings required must also be considered. Results are documented with their location and survey conditions. The specialist assessment determines whether a supplementary method is needed; this remains a project-specific 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 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. A necessary survey remains part of the agreed approach; visual checks supplement it. Site management needs a clear description of when specialist work takes place, how new findings are handled and which areas remain unresolved.

Agree the approach during construction
Technical assessment

Compare investigation questions and results for each area

What was checked using the aerial photographs?

The aerial-photo analysis must be read together with its explanations. The cited Airport West 2 draft explicitly distinguishes indications of air-delivered ordnance from other possible explosive ordnance. The information concerns that planning area, not your property. Check your own report to identify which ordnance types and indications the assessment addresses.

For existing aerial photograph assessments, compare the respective image capture dates and map sections covered. Later earth movements, fill or new structures are also checked against their own records. Where earlier aerial photographs do not show part of the area sufficiently, this limitation is taken into account in further hazard investigation. Any necessary supplement is commissioned with its specific investigation question.

When further surveying is necessary

For any necessary geophysical survey the investigation objective, local conditions and specialist limitations must be defined. Whether an area already investigated needs checking again depends on the existing results and current design. A result from a neighbouring area does not answer unresolved questions for your own area.

Ground conditions, existing services, reinforcement and other interfering objects can affect a measurement’s suitability and interpretability. The specialist planners select the method according to the target objects, the volume of ground required and actual measurement conditions. For a requested borehole clearance, the starting point, drilling depth and elevation reference form part of the commission’s basis. A survey report links the areas actually investigated with methods, results and remaining limitations.

Requirements for supervision during construction

During construction-phase ordnance clearance the necessary technical investigations are incorporated into the excavation sequence. The DGUV FAQ explains that visual observation alone, without this specialist work, does not meet the state of the art for this task. The approach is planned with investigation sections, protective measures and reporting channels. Accessibility and timing are considered in specialist method selection.

If the specialist assessment identifies further clearance needs, the clearance objective and spatial scope are defined. Area clearance is described with its purpose, accessible areas and actual construction conditions. Where explosive ordnance is identified, recovery and further measures are coordinated with the competent authorities within Lower Saxony’s allocation of responsibilities. The survey report and clearance record document the specialist work carried out, together with its conditions and limitations.

Next steps

Compile reports for the next groundworks

01

Identify the project location and next groundworks at first contact

Assign an author, date, plan appendix and investigated area to each report. Request missing appendices and record what remains outstanding. If a summary and detailed report appear inconsistent, clarify the relevant statement before using it further. For the first discussion, identify the specific project address, current site plan and first planned groundworks. State which decision the planners need and who is bringing the existing records together.

02

Check documents and assess unresolved historical questions

For each area, record whether there is an assessment, recommendation, completed investigation or official requirement. These may complement one another but are not interchangeable. A newer report does not replace an older one merely because of its date. The area and question it addresses are decisive. Documents are checked for their spatial conclusions, investigation question and completeness. If the specialist basis remains unresolved, the necessary historical research and wartime aerial photograph assessment are carried out. Their findings and limitations provide a basis for further investigation planning.

03

Select methods and coordinate responsibilities

Lower Saxony’s information on responsibilities distinguishes commercial hazard investigation from statutory municipal measures and the KBD’s tasks. Refer unresolved questions to the respective competent body. Record in the commission which investigation results are required. Necessary decisions by the competent authorities remain separate. The specialist planners select a suitable method according to the investigation objective, intervention depth, ground conditions and interference. For each area, the planned specialist work, required access and prerequisites for execution are defined.

04

Survey or provide specialist supervision and assess results

The agreed surveys or specialist supervision work are carried out in the defined areas. Measurement data and anomalies are assessed with reference to the methods and local conditions. Areas that cannot be investigated remain separately documented. An actual suspected find requires the affected work to stop and the competent authorities to be notified immediately.

05

Document and hand over the report and site plans together

Before the relevant ground intervention, the documents applying to that area are handed over together. They explicitly include limitations and unresolved matters. Where needed, compile an overview of the documents. The next intervention is based on the areas actually documented and the specialist limitations of the findings. The documentation identifies methods, areas and depths actually investigated, and remaining limitations. The report and plan appendices are handed over together to the agreed recipients. The assignment remains traceable even if site management or contractors change.

06

Compare subsequent ground interventions with the documented results

Before the next groundworks, their position, depth and execution are compared with the existing findings. Relocated structures, additional connections or new construction sections receive their own assignment. Unresolved questions and necessary supplements are handed over to those involved with the associated plan version for the next decision.

Documentation

Document completed work separately from remaining tasks

Findings and their scope

The final report must show where investigations were carried out, which method was used and which limitations apply to the results. If only part of the project was investigated, this must also be evident in the overview plan. The documentation for a specific measure is retained with its appendices and checked for applicability when later changes occur.

Project responsibilities

Specialist documentation must be distinguished from an official order or decision. The BFR Kampfmittelräumung provides specialist principles for organising documents within its stated scope. Any additional requirements for a specific Langenhagen project must be clarified with the responsible parties.

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 findings are identified. They are shown separately in the report and overview plan. Planners and site management can then decide specifically which areas still need work and when a suitable investigation will become possible.

Clarify changes before intervening in the ground

A new location, additional depth or different construction methods are compared with the existing results. Changes are passed on with dates and clear plan references. Feedback is provided before the affected work so that an unresolved question can be incorporated into the workflow.

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.

Understand investigation reports and their limitations

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 differing investigation stages in Langenhagen

Does a result without indications apply to the entire project?

Only if the investigation actually covers the entire project and the relevant questions. A result for one area must not be applied to the remainder. It must also remain clear which explosive ordnance question the respective method actually investigated. Before the planned groundworks, agree the required investigation scope with the specialist company and the official requirements with the City of Langenhagen. The state explosive ordnance disposal service supports the municipality within its remit.

What does a reference to clearance in a development plan establish?

It may indicate that work was carried out. Before using this information further, check the associated report, the actual area and the documented limitations. The brief reference alone does not replace these documents.

Can different recommendations apply within one planning area?

Yes. The draft for Airport West 2 documents different results for individual areas. For your project, check each recommendation together with its associated area and investigation question. The project name alone does not identify which area was investigated.

Does an area already investigated need to be checked again?

This depends on what the existing report establishes and on the new design. Different ground interventions, changed depths or additional findings may require reassessment. This does not automatically mean that all investigations must be repeated.

How should a suspicious object be handled?

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.

Can a coloured overview map replace the complete reports?

The map helps orientation but must refer to the underlying records. The complete documents explain which question was investigated and which limitations apply. Where individual areas differ, their findings are assigned separately rather than inferring a uniform status solely from a shared colour.

What happens if a final report mentioned in the records is unavailable?

The report is requested from the responsible party and recorded as a missing document until the matter is clarified. A reference to its existence does not establish its precise scope or result. Whether supplementary specialist measures are necessary is decided using the complete available information and the planned ground interventions.

What information makes quotations for the remaining task comparable?

Identify the unresolved areas, depths and investigation questions, together with all existing results. Describe access, required preliminary work and the expected documentation. Work already carried out and tasks still outstanding must be distinguishable so that quotations relate to the same actual investigation scope. Together with the selected method and local measurement conditions, this information determines the work involved, timing and costs.

Project enquiry

Check existing reports for your project in Langenhagen

Assign reports together with their plan appendices

Provide the complete existing assessments, technical reports and official correspondence. Add a register showing which document belongs to which area. Missing appendices or follow-up reports that are merely mentioned should remain identifiable so that further clarification can be targeted.

Mark new ground interventions and unresolved questions

On the current site plan, mark the planned groundworks and depths, together with changes from earlier investigations. Identify the next construction section, the decision needed and the responsible contact. This allows existing results and the remaining task to be compared transparently.

Add the project address, land parcels, current project status and planned construction dates. Provide official conditions with their appendices. Attach existing service plans and as-built plans, identifying their respective versions.

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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