Technical map view of the Darmstadt administrative district with Darmstadt marked for explosive ordnance assessment and surveying by FONTANA-EOD

Explosive ordnance surveying for your Hanau construction project

Project owners, design practices and site managers need a clear investigation commission and complete results documents for groundworks in Hanau. FONTANA-EOD supports review of existing information and the agreed explosive ordnance investigation. Send the site plan, proposed groundworks depth, official statements and existing reports so that technical scope, contacts and next steps can be agreed.

Commission

Identify the area and results needed.

Coordination

Agree contacts before work begins.

Documentation

Pass outstanding questions to site management.

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

Coordinate the technical commission and official duties clearly

For your Hanau construction project, we describe the commissioned investigation and expected results within their specific scope. The duties of public bodies remain separately identifiable. Before work begins, we clarify who receives the results and how outstanding questions will be addressed before subsequent groundworks.

Project references

Selected project examples

Project site

Connect the site with the specific construction task

Schematic map with a coat of arms and state colours, alongside a tablet, safety helmet, pen and notebook.

Identify Hanau and the actual project location

The city’s notice of 17 July 2024 describes a find during surveying and its subsequent defusing by the state explosive ordnance clearance service. For your project, the investigation commission, handover of results and duties of public bodies are likewise clearly distinguished. Your own workflow is prepared for the specific area and coordinated with the parties actually responsible.

Hanau has been an independent city since 1 January 2026, in the Darmstadt administrative district in Hesse, Germany, and therefore does not belong to a county district. For the project, state the actual address and proposed groundworks. For a project in another municipality, such as one in the Main-Kinzig district, identify that municipality. Responsibility follows the project location and technical task; the explosive ordnance clearance service at Darmstadt Regional Council is responsible throughout Hesse.

Hesse
Local context

Investigation and emergency response have different duties

Relate the Hanau find to that specific event

On 17 July 2024, the City of Hanau reported an air-dropped bomb found during surveying. The explosive ordnance clearance service at Darmstadt Regional Council undertook its defusing; other public bodies were involved in the measures required. The notice concerns only that operation at that time. It does not support a conclusion about other properties.

Clarify responsibilities for your own construction project

The allocation of duties nevertheless matters for project planning: a commissioned technical investigation and official measures in response to a specific danger are different steps. A survey appointment therefore does not promise that every possible follow-up question will be resolved that day. Before work begins, agree who receives investigation results and how outstanding points are taken forward into subsequent work.

Hanau’s municipal museums describe the air raid of 19 March 1945 and severe destruction of the city centre, infrastructure, railway and industrial facilities. Reconstruction changed the cityscape. For a current construction task, available historical indications are assigned to the specific property. Known changes caused by rubble clearance, filling or later construction form part of the document review with their location and elevation references. For a formerly used area, clarify which findings exist and which ground volumes the new groundworks actually affect.

Working together

Allocate tasks within the construction project

Client and operator

The client describes the project and provides the available project documents. The operator adds requirements relating to use, access and scheduling. The participants agree their respective tasks and decision-making responsibilities. A coordinating contact person brings the project information together. Before an appointment, it is recorded clearly which information is missing, who will obtain it and which decision the result is intended to support.

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 carries out the agreed investigation and documentation. Official requirements and decisions are clarified with the competent bodies. Documents needed for a specific procedure depend on the site and project. The technical report describes the specialist work completed with its spatial extent and limits. Its applicability to further groundworks is checked against the specific ground disturbance. The competent bodies make official decisions.

The KMRD based at Darmstadt Regional Council is responsible for all of Hesse. Suitable specialist contractors are commissioned for technical investigation or clearance within the respective permit and competence framework. Under Hesse's General Provisions, defusing, blasting and removal are reserved exclusively to the KMRD or a person commissioned by it. Assign the competent authorities and responsible specialists clearly before the task concerned.

Investigation task

Which specialist task comes next?

Align the investigation with the conclusion needed

The suitable specialist service is determined from the planned groundworks, existing findings and site conditions. The commission describes this specific contribution. It does not change official responsibilities. Method selection and expected limits of conclusions remain transparently connected to the area and question to be addressed.

Compare specialist services for the conclusion needed

Determine a subsequent service from the results

If a report identifies further needs, define the unresolved question before placing another commission. Consider the area affected and proposed groundworks together. Continuing without a clear commission makes later traceability difficult. The next specialist service therefore follows explicitly from the documented findings and limits.

Compare investigation methods
Project types

Connect responsibilities, specialist work and handover of results

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

Identify the agreed technical commission unambiguously

Record which area and question the commissioned investigation concerns. The expected documentation is linked to this task. All participants can then understand the intended contribution. A general project title or survey date alone does not describe every service that may become necessary later.

For a bill of quantities, describe the initial records, investigation objective and spatial scope together. With several construction stages, record which part is needed first. An accessible utility area and an excavation accessible only later may be at different stages of investigation. The quotation identifies the associated specialist service, preparation required and expected results documents. For an additional ground volume, agree the suitable supplementary work before work on it begins.

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

Agree the recipients of the results

Before execution, identify who receives reports and plans and passes them to the next construction phase. The responsible person needs the complete conclusions and restrictions. Brief verbal information can support coordination. For later design changes, the written records must remain available with their spatial reference.

Record who provides the complete documents for execution, technical planning and the project owner. The handover covers the areas actually treated, elevation and depth references, and remaining restrictions. Recipients compare this information with the next construction phase. Any part of the investigation still outstanding is identified separately. Even with separate construction contracts, the technical conclusion remains tied to the documented specialist task.

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

Assign unresolved questions to further tasks

If questions remain after an investigation, describe them with the area affected and the next clarification needed. Responsibilities are agreed transparently. Completion of an individual service can coexist with outstanding subsequent steps. The project overview therefore shows both the existing results and decisions still required.

An unresolved question may concern a missing plan appendix, an area whose data cannot be interpreted, a deepened foundation or a rerouted utility. State the specific difference from the previous position. The responsible parties then determine which information, technical assessment or additional work is needed. New results are subsequently brought together with the earlier records. It remains clear which conclusion is being reused and which scope has actually been added.

Coordinate the sequence and tasks
Preparation

Prepare the scope and commission together

Establish what needs to be known before commissioning the work

Describe the investigation needed in the commission with its area, groundworks depth and existing findings. Clarify whether the task is to assess records, technically investigate particular ground volumes or carry out further work on findings already assessed. Also identify who receives the report and assigns unresolved questions before the subsequent construction work. The commissioned specialist service and any further official steps retain their respective scope. An investigation quotation can then be agreed against specific underlying information and expected results documents.

Define the specialist task

Coordinate preparatory work with the investigation

Preparation connects the work areas needed with available access, utility information and the activities of other trades. Responsible contacts agree the surveying conditions required for the suitable method. Demolition, changed surfaces or additional investigation access receive their own technical planning and necessary prerequisites. They are not arranged independently merely to prepare for the survey date. Before execution, agree how local restrictions and new findings are communicated to the parties responsible for subsequent work.

Clarify preparatory work in the programme

Agree a clear scope and schedule

The scope of private specialist work is agreed using the project documents, actual execution conditions and permissible activity. Necessary preparatory works, investigation, evaluation and documentation are described transparently. Costs and dates are related to these prerequisites and the required coordination. Changes to the construction plans are checked against the agreed contract before work is extended.

Discuss the scope and schedule
Tasks at the site

What belongs in the technical commission

01

Define the investigation area clearly

Have the proposed investigation area shown on a site plan. Include the relevant groundworks and depths as far as these are known. Also identify areas outside the commission. Site management can then distinguish which activities the results cover and where additional assessment is still missing.

The work area may also include shoring, ancillary pits, site access roads and utility connections outside the later building footprint. If excavation geometry changes, identify the volumes affected on the current plan. Elevations refer to a named reference; known filling or excavation is communicated. Preparatory groundworks are recorded with their actual intervention so that necessary investigations and protective measures can be clarified before execution.

02

Provide existing official statements

In Hesse, the explosive ordnance clearance service based at Darmstadt Regional Council provides information about possible contamination of properties. For an enquiry, it requires a precise plan with marked property boundaries; an online application for aerial photograph evaluation is also available. If a statement already exists, include it and its associated plans in preparation of the technical commission.

03

Clarify decision-making responsibilities on site

The project owner’s responsible contact should be reachable if results or site conditions differ from expectations. Also record who passes on revised plans. Organisational preparation records contacts, plan revisions and handovers transparently. Technical assessments and official decisions remain with the relevant responsible parties; written records are available to participants joining or replacing others.

04

Do not silently extend work steps

An investigation commission does not automatically include every possible later clearance measure. If further needs arise, their technical prerequisites and scope must be clarified. The same applies to revised construction plans. For a reliable agreement, describing the outstanding task is more useful than continuing the previous commission without review.

Project documents

Documents that establish the next step

Keep technical reports and official notifications distinct

Both types of document may matter for the workflow, but serve different purposes. Record their content, date, spatial reference and responsible body. A shared file makes access easier. An organisational notification is not described as a technical investigation report, and a technical report is not expanded into an official decision.

Consider the next groundworks at handover

Check together which groundworks are planned next and which findings are already available for them. Assign unresolved questions clearly. The report remains available with its appendices. The next construction phase can then build on the documented position, even if participants or design details have changed in the meantime.

If results are handed over by stage, the project overview states progress for each area concerned. Preliminary information is distinguished from completed technical assessments. A section becoming accessible later receives the clarification it needs before the proposed intervention there. When contractors change, complete plans and reports are passed on with outstanding tasks. After clearance work has been carried out, the clearance record, stating clearance scope, results and remaining limits, is also assigned to the section actually covered and relevant site plan. The current construction plans and investigation scope actually completed remain separately traceable.

Construction sequence

Coordinate investigation and construction sections

Agree the allocation of duties before work begins

Compile the current groundworks plan and existing records. Identify the client, specialist participants and recipients of the results. Give the commissioned investigation a clear scope. Coordination also identifies which other bodies are involved and which requirements remain unresolved before the groundworks concerned.

Coordinate the construction phase with us

Prepare subsequent execution from the report

Site management compares the new results with the next intervention and includes unresolved questions in the task overview. Technical or official clarification still required remains identifiable. A date for subsequent work is agreed against these requirements. The documentation thus forms the basis for the next activities without anticipating unknown results.

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 evaluation and other older records help locate the basis for suspected contamination. For the commission, available images, their dates and limits of conclusions are related to the current groundworks. Other existing findings receive a traceable reference to the same area. This evaluation supports assessment of investigation needs, but does not document a survey of the present-day subsurface. The absence of an identifiable indication must therefore be distinguished from a technical field investigation and the actual scope of its conclusions for the proposed work.

Understand aerial photograph assessment

Magnetometric survey

Magnetic surveying methods detect magnetic anomalies. For the agreed investigation task, expected objects, the ground volume needed and local interference are technically assessed. Existing structures, utilities or fences can affect interpretation. Interpretation assesses survey signals and records any further clarification needed with its spatial reference. Signal strength alone does not identify explosive ordnance. The handover of results therefore provides a technical conclusion rather than merely a list of anomalies. Magnetometry measures the magnetic field passively. Detection depends on the magnetic effect of the object sought; electrical conductivity alone does not establish that this method can detect it.

Understand the scope of magnetometry

Electromagnetic methods

Electromagnetic investigations may be suitable for certain metallic target objects and site conditions. Their selection is justified against the specific task, accessible work areas and interfering installations. Results are documented with their location and actual investigation conditions. Technical assessment identifies any addition required and makes the outstanding scope clear for further coordination. An available device does not replace this commission-specific decision. Transient electromagnetic methods, or TDEM, evaluate the time-dependent electromagnetic response of conductive objects. The method is selected according to the investigation objective and actual surveying conditions.

Understand electromagnetic surveying

Ground-penetrating radar

Under suitable conditions, ground-penetrating radar can provide information about subsurface structures and reflections. The conclusion needed is defined in the commission and assessed against ground conditions, moisture and installations. The report states interpretation and limitations of the data actually evaluated. Anomalies are not automatically explosive ordnance; areas without anomalies do not establish findings to arbitrary depths. If a report prepared for another technical purpose is submitted, its suitability for the explosive ordnance question is checked first.

GPR and limitations

Deep-ground and downhole surveys

For deep excavations and foundations, the assessment checks whether a surface investigation can provide the conclusion required or whether a different approach is needed. Deep surveying or borehole surveying receives specific planning of starting points, depths, arrangement and existing utilities. Suitable investigation access and its creation are technically prepared. A general depth figure or standard grid does not replace this definition. The report assigns results to the ground volumes actually covered and method used.

Prepare deep interventions

Survey during construction

If the necessary preliminary investigation cannot be completed in full, the technical suitability of an approach alongside construction is assessed. The relevant work areas, investigation and interpretation steps, and reporting of new findings are coordinated with the construction sequence. Visual observation during excavation alone does not replace the survey needed. After each stage, site management needs the technical findings reached, remaining limits and outstanding tasks. The responsible contacts and requirements for the next groundworks are clarified in advance.

Agree the approach during construction
Technical assessment

Which information is missing for the next step

Compare historical information with the construction area

The Aerial-photo analysis assesses indications in historical images. Its conclusions must be assigned to the current construction area. If several reports exist, read their reference areas and results together. Contradictions or missing appendices need clarification before further planning. Merely mentioning an investigation at a neighbouring site does not support a conclusion about your project.

Assess technical results professionally

The Surveying must match the investigation task and site conditions. Survey data may require further technical clarification; its mere existence does not constitute complete evidence of completion. Ask for an explanation of what could be interpreted, which areas remained restricted and what conclusion follows for the planned interventions. Magnetometry detects magnetic anomalies; active electromagnetic methods and ground-penetrating radar have different conditions of use. For ground-penetrating radar, propagation conditions in the ground are decisive. Selection accounts for ground composition, existing utilities, interfering objects, the investigation objective and groundworks depth. For deeper interventions, any necessary deep surveying or borehole surveying is technically planned. Borehole clearance or technical evidence remains assigned to the ground volume actually investigated and the limits of its conclusions.

Plan subsequent work on a reasoned basis

If additional measures are needed, a Clearance plan can bring their sequence and evidence together. Professional explosive ordnance clearance alongside construction is not equivalent to simply observing excavation. A difficult-to-access area or one with poor interpretability does not automatically justify a particular alternative. The approach must match the clarified task.

Next steps

Coordinate investigation and handover of results with construction

01

Clarify the project and records

The initial contact identifies the project location, construction task and conclusion needed. Existing plans, official statements and reports are checked for currency, spatial reference, completeness and gaps.

02

Supplement historical information

Where historical questions remain unresolved, the necessary research and aerial photograph evaluations are carried out under a technically agreed commission. The KMRD statement is considered; supplementary findings are assigned to the current interventions.

03

Define methods and requirements

The suitable method is selected from the investigation objective, groundworks depth, ground composition, existing utilities, interfering objects and surveying conditions. The technical commission, access, preparatory work and necessary protective measures are clarified with those responsible before the groundworks concerned.

04

Perform the agreed investigation

The agreed surveying or proper investigation during construction is carried out within the permitted specialist commission on the areas and points agreed. Measurement data and observations receive clear position and elevation references. Uninvestigated areas, restricted access and relevant interference are recorded.

05

Assess survey data and findings

The collected data and findings are evaluated against the investigation objective. The technical assessment considers interference, the areas reached and remaining limits of the conclusions. It establishes which further investigation or work is needed for the planned groundworks.

06

Update the plan with the areas covered

The results drawing must identify the area actually covered. If a part was omitted because of an obstacle, this should be clear at handover. The originally proposed work area and the area actually investigated may differ. Without this comparison, an untreated corner risks being mistakenly included in the completed area. The report and plans document the specialist work performed, technical assessment, areas covered, and location, elevation and depth references with their respective limits of conclusions.

07

Define outstanding tasks specifically

Instead of a general note, identify which question still needs an answer. Is a report missing, is part of the data uninterpretable, or have the plans changed? These distinctions determine further coordination. Also state which activities the existing investigation does not cover until clarification.

08

Provide revised plans to the technical planners

If an excavation is extended or a deep structure relocated, for example, the responsible technical planners need the revised plans. A final report remains tied to its described investigation scope. A later design change therefore first requires comparison, rather than automatically commissioning a new investigation of the whole property.

09

Record requirements for continuing work

Where a find is confirmed, the responsible authorities determine subsequent action. For construction to continue afterwards, also clarify which work areas and conditions the existing evidence actually covers. A lifted closure should not be reused without review as comprehensive investigation evidence for every future intervention. Site management and technical planners compare the records with the next specific groundworks and agree necessary additions or changes with the responsible parties.

Documentation

Document technical reports and official measures separately

Findings and their scope

Retain the commissioned investigation reports, plans and any official notifications with their respective purposes. Verbal handover is not sufficient for later design changes. The records should show which areas were covered, which results are available and which questions remain. Participants joining later can then understand the position reached.

The General Provisions for Hesse specify site plans at a scale of 1:1,000 and submission of results to the explosive ordnance clearance service. The technical commission, actual progress and relevant plan version remain available together in the project file. A later addition is transparently assigned to its area and date.

Project responsibilities

The explosive ordnance clearance service at Darmstadt Regional Council is responsible throughout the state and arranges removal and, where necessary, defusing and destruction of explosive ordnance. FONTANA-EOD delivers the agreed specialist services within their respective investigation and documentation scope. The responsible authorities make the official decisions. The BFR KMR apply directly to federal properties; for other projects, their principles are used here as technical guidance.

Working approach

How FONTANA-EOD works

Document the agreed specialist service clearly

FONTANA-EOD describes the agreed investigation with its available records, actual work areas and results needed. After execution, the designated recipient receives the report, including documented limits and outstanding questions. The technical position reached remains distinguishable from any subsequent official measures. If plans or surveying conditions change, further technical needs are compared with the commission. The next groundworks are related to these specific results and the decisions still needed.

Discuss the investigation task

The task before the equipment

Before equipment is selected, establish which information is missing for the next construction decision. Existing records and local surveying conditions form the basis. A method from a similar project or an equipment name determines neither your own investigation scope nor the results needed.

Keep limitations visible

Inaccessible areas and restricted interpretations are identified in the report with their spatial reference. They remain identifiable for further work. The designated recipient can then assign the technical task still required and its prerequisites to the construction stage concerned, rather than treating an incomplete position as overall completion.

Clarify changes before intervening in the ground

A new area, changed depth or different construction method is compared with existing results before the intervention concerned. The current plans show what has changed from the commissioned scope. Those responsible use this to clarify further investigation and coordination required before the new task is carried out.

Hand over the report and plan together

The report and plans are handed to the agreed contacts with their full scope of conclusions. Progress reached, restrictions and outstanding subsequent tasks remain connected. A summary helps with orientation, but does not replace the records. Subsequent site management or a specialist contractor also needs this basis to assign further steps and responsible parties transparently.

Understand the results

Use technical statements for the next decision

A clear handover preserves the technical context

The report, site plan and limits of conclusions are passed to the responsible participants together. Even a brief summary refers to these complete records. This keeps clear which question was actually addressed. An individual sentence forwarded without appendices cannot reliably communicate the spatial and technical scope of the results.

Understand investigation reports and their limitations

A new participant needs the current records

When site management or the specialist contractor changes, the valid plan revisions, existing findings and outstanding tasks are handed over together. Earlier responsibilities remain traceable as project history. The current allocation of duties is clarified for the next activity. A shared project address alone does not ensure that all participants mean the same area and task.

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 commissions and construction workflow in Hanau

Does a clearance service statement already constitute the technical investigation?

No. The statement assesses available findings and may identify work required. Whether and how a technical investigation takes place must be clarified for the specific project and commissioned accordingly.

Which duties does FONTANA-EOD undertake within the agreed technical commission?

FONTANA-EOD undertakes the agreed review, investigation and documentation tasks within their respective scope. Official emergency response and required closures are arranged by the responsible public bodies. Under Hesse’s provisions, defusing, blasting and removal are the responsibility of the explosive ordnance clearance service or persons it commissions. Further services needed are agreed for the specific task.

Does the Hanau find in 2024 indicate contamination of my property?

It documents the event described by the city at that time. It does not establish contamination or a completed assessment of your property. Your own property records and planned groundworks must be assessed for that purpose.

What should site management receive after the investigation?

It needs the results with their associated area plans, limits of conclusions and outstanding tasks. The evidence must match the proposed construction stage. If that stage changes, the previous coverage must be checked again.

How should I respond to a possible find?

Stop work in the area concerned, do not touch or move the object and keep your distance. Warn others and call the police on 110 from a safe distance. Further handling is reserved for the responsible specialists. Do not expose the object further or take it to a police station or other official premises. Leave the danger area and keep others away.

Why should the investigation report’s recipient be agreed in advance?

So that results, appendices and outstanding questions reach the next construction phase in good time and can be taken forward unambiguously.

How is a question left unresolved after the investigation taken forward?

It is recorded in the project overview with the area affected, clarification needed and responsible participants.

Which cost factors matter for an investigation in Hanau?

The work involved depends on usable previous records and the KMRD statement, preparation and access required, area size or number and depth of investigation points, suitable method, surveying conditions, interpretation and documentation. Unresolved areas and supplementary tasks are quoted with their actual prerequisites. Private specialist services, official duties and other preparatory services remain distinguishable within the service scope.

Project enquiry

Prepare the first technical discussion

Define the technical commission

Describe the area, proposed groundworks and existing findings. Add the actual project address, parcel numbers, file reference, groundworks depth and a current site plan. Attach existing official statements and complete reports with appendices. Describe construction progress, access, existing utilities and known ground alterations. Identify the construction stage needed first and mark additional working volumes. Missing information remains identifiable as outstanding points so that the specialist service needed can be defined specifically.

Identify participants and handover responsibilities

State who receives the results and coordinates subsequent work. Identify the client, site management, technical planners and coordinating contact with the proposed schedule. Recipients receive the associated reports and plans with the outstanding questions. With several trades or construction contracts, record who compares the findings before the next groundworks. Also state which activities should begin first and which areas become accessible only later.

GPR on a construction site
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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