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

Explosive ordnance surveying and disposal in Hanover

For project owners, planners and site management, FONTANA-EOD compares existing aerial photograph analyses, official information and earlier survey reports with the construction project in Hanover. The review establishes which areas and depths the documents cover and which further investigation is needed for the planned ground intervention. Send the site plan, construction task and complete reports with appendices for technical coordination.

Available documents

Review reports and accompanying maps.

Construction task

Record the project’s areas and depths.

Coordination

Clarify the commission and official procedure.

Discuss the construction projectExplosive ordnance assessment in Lower Saxony
Assess the construction project

When an explosive ordnance assessment becomes relevant to your project

The Hanover Fire Brigade explains how aerial photograph analysis helps prepare construction projects. An area shown in red may indicate bombing, wartime impacts or unusual ground discolouration. It therefore identifies an area requiring clarification, rather than an already confirmed individual explosive ordnance find.

Compare the complete analysis with its site plan and earlier survey reports against the current ground intervention plan. We compare the areas and depths covered with your planned earthworks. Unresolved areas, preparatory work needed and the investigation scope are agreed with planners and site management; the responsible bodies are involved according to their remits.

A local practical example is the GPR investigation at Vahrenheider Markt. The GPR service page explains the method’s limitations. For your project enquiry provide the marked construction area, ground intervention depths and existing results.

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

State the actual project location with a site plan and the affected properties. Existing information, official conditions and reports are assigned to this area. Hanover is in Lower Saxony in the Leine-Weser administrative area. Assign addresses in Mitte/Innenstadt, List/Oststadt, Linden/Limmer, Ricklingen, Vahrenwald/Bothfeld, Misburg-Anderten and Südstadt/Döhren to their respective site plans and documents. For enquiries from Langenhagen, Laatzen, Garbsen, Seelze, Hemmingen or the wider Hanover region, the project location and responsible municipality are identified separately. Within the city, the state capital Hanover is responsible for protection against explosive ordnance hazards; in the surrounding area, the relevant municipality must be involved. For each site plan, identify the corresponding document version and the body responsible for the project location.

Explosive ordnance assessment in Lower Saxony
Local context

What official information means for your project

Local starting point

On its page about suspected areas and construction projects, the state capital Hanover explains that a risk assessment may be based on an aerial photograph analysis by Lower Saxony’s explosive ordnance disposal service. An area shown in red indicates identified wartime impacts or corresponding indications. It is not equivalent to an already confirmed individual item of explosive ordnance. Where documents concern former industrial and storage areas, railway and route areas, or residential and redevelopment sites, these phases of use are compared with the present construction area. Information about relocated rubble or terrain changes is assigned to the affected area and planned ground intervention.

The Hanover City Archive records the dropping of high-explosive and incendiary bombs on the night of 8 to 9 October 1943. The Kestner Museum was also hit; building control documents stored in the destroyed Bauamtshaus were lost. When investigating the history of a construction area, available aerial photographs, maps and files are compared with former buildings and subsequent terrain changes. Gaps in surviving building files must be taken into account when reconstructing the history of use and construction.

Implications for construction planning

A specifically identified point suspected of containing an unexploded bomb is a different matter. For such points, the city describes a procedure for further technical investigation. Present any existing letter from the city at the project discussion. Clarify with the contacts named there which measures have already been arranged and which additional investigations you must commission yourself.

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.

As the municipality, the state capital Hanover is the responsible hazard prevention authority; investigation and elimination of hazards are assigned to its Fire Department. Lower Saxony’s explosive ordnance disposal service supports the municipality. For suspected unexploded bomb points already coordinated by the city, their processing status is clarified with the responsible contact. Any additional private hazard investigation measures required are commissioned with their own defined area and service scope.

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

Bring construction tasks and suspected areas in Hanover together

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

Excavation within a marked area

For an excavation, current planning is compared with the geographical scope of the existing information. What matters is whether the excavation, including working space, shoring and other ground interventions, intersects the area considered. A coloured area marking conveys different information from an individually identified suspected point. Both must be included in full in the enquiry. This establishes the further clarification needed before the intended ground intervention.

For existing technical reports, the elevation reference also matters: if the terrain has changed, a depth below the former ground surface can only be correctly located using current elevations. State the planned excavation base and underside of foundations or shoring elements. Where different working areas are needed for individual construction phases, these remain separately identifiable. Specialist planning can then determine whether the documented scope fits the current construction task or whether additional areas and depths require clarification. Coordination is based on the dated planning version that is subsequently intended to be used for the investigation.

Provide specialist supervision of excavation
Illustration: two people with a tablet beside a drawing table and a survey trolley on a construction site.

Utility route with changing conditions

Sections of a utility route may lie both inside and outside a depicted suspected area. Chambers, launch and reception pits or lateral working areas are additional considerations. Describe these areas with their respective depths. A utility alignment shown as a single line is often insufficient to define the technical task. Even a short connection to existing infrastructure is compared with the investigation scope if further groundworks are planned there.

For the enquiry, divide the alignment into traceable sections with their width, intended depth and associated excavations. Assign existing explosive ordnance documents and known installed structures to each section. A transition from open ground to a surfaced access route may mean different measurement conditions; the suitability of the approach is therefore explained for each section. Designations also remain clear for the results handover. If a connection is subsequently moved or its depth changes, it is possible to identify which part of the previous commission is affected and which question remains to be clarified before implementation.

Specialist services and investigation tasks
Illustration: two people review plans and documents at a table beside a construction vehicle.

Specific suspected point within the construction sequence

If an individual point is already being investigated by the city, its processing status is obtained first. The construction project needs to establish which investigation has already been arranged and which additional private specialist service is actually required. The two are kept separate spatially and organisationally. Commissioning the same task twice does not provide additional findings; rather, the complete existing file helps plan appropriate follow-on work.

The processing status includes the date and subject of previous steps, the accompanying plans and any existing file reference. Identify which measure has been requested, commissioned or already carried out and which body coordinates the next step. The new construction planning is compared with this status. This distinguishes an additional private investigation for the excavation or utility from investigation of the specified point. Results are passed on with their spatial reference. Site management and the client can identify which response a particular task depends on and who provides any documents or information still missing.

Document findings and their limitations
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
Documents and construction planning

What do the documents establish about the construction project?

01

Analysis for the correct area

Check whether the mapped application area fully encompasses the subsequent ground intervention. An earlier construction project may have involved a smaller area or different ancillary work. Added access routes, connections or working pits must also be included in the technical assessment. An address alone does not show which areas the work affects.

02

Area indication and individual suspected point

An indication of a suspected area describes a different starting point from an individually located suspected point. The legend, explanatory text and accompanying plan must be read together. The colour of a map section determines neither a ready-made investigation method nor a general time requirement.

03

Excavation and deeper structures

In a hypothetical new construction project, the excavation base, a deeper chamber and individual foundation elements may reach different depths. Show these differences in the planning. The investigation scope must take these depths into account. A report for the general construction area does not automatically cover every deeper ground intervention.

04

Preparatory earthworks

Ground investigation works, exploratory excavations or temporary utilities may precede the main construction work. Identify this preparation early. If the ground still needs to be investigated for it, clarification must not wait until the main excavation.

Project documents

Documents that establish the next step

Provide the information with its map

Send the complete letter, including the map, legend, date and any identified suspected points. A map excerpt without explanation may leave it unclear whether it concerns a general area designation or a specific investigation. The construction planning is included as a separate, current plan. This keeps the origin and meaning of the two documents clear.

Identify work already commissioned

State which measures have already been commissioned, who expects a response and which results are available. This is particularly helpful when official procedures and private construction preparation proceed simultaneously. FONTANA-EOD can then relate the requested scope to the unresolved specialist task rather than having to infer the status from individual emails.

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 methods

Determine investigation requirements from the report and construction planning

Review the aerial photograph analysis

The historical aerial photograph analysis provides information about the former situation. It must be distinguished from a technical investigation in the ground. Its spatial boundaries and specific recommendations inform further planning. Missing assessments are treated as unresolved questions, not as confirmation that there is no risk.

For the comparison, the assessment, analysis plan and available appendices are read together. Marked areas and individual indications are transferred to the current site plan; their designations and the source of each assessment remain traceable. A reservation mentioned in the analysis is translated into a specific question for further investigation, for example about the area covered or available photographic material. If several versions exist, their dates and corresponding appendices are identified. The remaining areas and questions determine the additional research commission. The results then help establish the need for and spatial scope of a technical investigation.

Choose a suitable technical investigation

Whether a surface survey, a depth-specific investigation or a combination is suitable depends on the task and measurement conditions. Known installed structures, surfacing and fill must be taken into account. A fixed detection depth or method range cannot be derived from a general description of the location.

Describe the current condition of the areas, known utilities and installed structures, and relevant changes caused by filling or demolition. Current photographs can supplement the documents; the position and depth of planned groundworks remain identifiable in the plan. Specialist planning assesses what can be established under these conditions and what the measurement requires. Necessary access and preparatory work are assigned to a specific area and agreed with those involved before implementation. For commissioning, the accessible areas, intended investigation and required results documents are described together. Limitations remain assigned to a traceable part of the construction area.

Investigation during earthworks

If ordnance surveying during construction is technically necessary, its task must be coordinated with the earthworks. The DGUV explicitly distinguishes this technical investigation from merely observing excavation. Methods, investigated subareas and remaining limitations must be documented.

Before implementation, agree which responses site management and the executing contractor need for the individual working areas. These include the current processing status, spatial allocation of results and unresolved tasks. If the work sequence changes, specialist planning must be able to identify which ground intervention comes next. Interim results are handed over with their date and planning reference so that everyone involved uses the same version. Where anomalies occur, the agreed reporting channels and responsibilities are followed. Subsequent work is compared with the results actually available; additional areas or depths receive their own technical clarification.

Next steps

How to prepare the investigation

01

Gathering the records

Have the analysis with its complete accompanying plan, earlier reports and official letters available. If information about former use or wartime events is missing, additional historical documents are researched and suitable wartime aerial photographs analysed where available. Results and the limitations of the analysis are assigned to the present ground intervention area.

02

Draw ground interventions

Clearly define the main structure, ancillary work and depths.

03

Identify missing information

Identify missing investigations, unclear spatial references and measures already arranged.

04

Agree the scope of service

Before work begins, clarify which work is commissioned privately and which is arranged by the authorities. The method is selected according to the investigation objective, ground intervention depth, soil structure, utilities, sources of interference and accessibility. Its suitability and necessary preparatory work are explained for the individual areas.

05

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.

06

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.

07

Hand over the report and results plans

The report identifies the method, areas addressed and limitations of the assessment. Results plans and, where applicable, a clearance record document the position, depth, findings and results of the work carried out. Planners and site management receive the documents for the next ground intervention together with any unresolved tasks.

Documentation

Who is responsible, and what belongs in the report?

Findings and their scope

In Lower Saxony, municipalities are responsible for official hazard prevention. According to the LGLN’s description of responsibilities, commercial specialist contractors carry out commissioned hazard investigation measures; the state explosive ordnance disposal service is responsible, among other tasks, for recovery, defusing and disposal. FONTANA-EOD’s investigation documents the commissioned technical scope. The responsible bodies make the official decisions.

Project responsibilities

The initial documents and technical results report are kept together in the project file. The report must be relatable to the areas and depths actually investigated. Changed construction plans, areas not covered and indications requiring further clarification must be compared before subsequent ground interventions.

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 explosive ordnance assessment in Hanover

Does a red area mean that a bomb has been found?

No. The depiction must be interpreted using the corresponding analysis and legend. An indication covering an area and an individual point suspected of containing an unexploded bomb are different starting points. The available findings and the project determine which further assessment is required.

What does the KBD need for a wartime aerial photograph analysis?

The current official guidance specifies, among other things, the unambiguous location of the application area and suitable maps marking that area. Applications on behalf of third parties must meet the conditions stated there. Use the KBD’s current information and forms; your construction plans should refer to the same area.

Does a letter from the city replace my investigation commission?

That depends on the content and subject of the letter. Present it during the technical coordination. Investigation of a specific suspected point that has already been arranged and investigation of other construction areas may be different tasks. Duplicate commissions and unresolved gaps should explicitly be avoided.

Can I use an old investigation for a new building?

An existing report can provide a starting point. Before using it, its area, depth, method and limitations must be compared with the new ground intervention. An unchanged address is insufficient if the construction boundary or foundations have changed.

Who should I contact about a current find?

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.

What should be done if an excavation is moved?

The new position is compared with the existing information and investigation boundaries. Even at the same address, the shift may affect an area not previously investigated. Provide both the old and new planning versions. This comparison and the technical assessment determine whether further investigation is needed.

Which factors determine the investigation scope and costs?

Area, ground intervention depth, document version, soil structure, interference from metal and access determine the investigation task. Necessary preparation, evaluation, investigation of findings and documentation are additional factors. Work already commissioned and existing results are taken into account so that the quotation describes the task actually still required. Unresolved quantities or access conditions are agreed before implementation.

Can the investigation begin before the final route is selected?

An earlier investigation may be useful if its area and information objective are already sufficiently defined. Multiple options are explicitly described. The result is later compared with the selected route, including working areas; indiscriminate transfer to every conceivable option is avoided.

Project enquiry

Send the site plan and existing reports

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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