Forest fire in Wahner Heide: Fighting the fire from a distance

On 7 July 2026, SAT.1 NRW reported on the forest fire in Wahner Heide. According to the report, firefighters were not allowed to enter the affected area. They fought the fire from a distance, with a helicopter also deployed. Ordnance in the ground restricted access to the area where the fire had to be tackled.

In the interview, Oliver Fontana explained the danger posed by heat: Ordnance buried in the ground can also explode. Explosions and fragments endanger emergency personnel. Being below the surface does not remove the danger described in the report.

For owners and managers of woodland and green spaces, looking at the visible surface is therefore not enough. The history of the site and existing evidence of ordnance also matter when planning work. Renewing a path, removing a root or laying a utility line makes a difference to the investigation required. Its scope depends on the affected area and the actual ground disturbance.

Watch the video on SAT.1 NRW

A vegetated area looks different from a construction site in everyday use. Tall grass, dense trees or an undisturbed surface do not, however, reliably indicate what lies below. A site's previous use and specific evidence help establish whether ordnance is suspected. Relevant information may include existing assessments, records, reported finds or evidence of former military use.

The location matters: Evidence must relate to the area where work is planned. A report of a find in a region initially records an event at a particular place. It does not establish the precise position or depth of an object on another property. Equally, a site's long, undisturbed use does not replace a ground survey when a new project involves a different type of ground disturbance.

Owners should therefore keep existing documents together and in order. Plans, survey reports and records of later changes make it easier to answer the next project enquiry precisely. A plan clearly identifying the relevant area is more useful than a general statement that the site was checked at some point.

During an incident, the responsible incident command decides how emergency personnel proceed. It assesses the current situation using the available information. Anyone not involved in the response must observe cordons and official instructions. Do not enter an affected area to carry out your own investigations or gather supposedly useful additional information.

Later construction or maintenance work first requires a precise description of the project. This includes the exact area, the proposed activities, possible ground disturbance and existing documents. These details allow specific questions to be put to the competent authorities and a suitable specialist contractor. A report on a previous emergency response is one source of information among others.

A completed emergency response does not therefore answer a future client's project questions. The end of a firefighting operation describes the status of that operation. Whether trees may subsequently be removed, paths renewed, utilities laid or foundations built, and under what conditions, depends on the particular project and its supporting information. This must be addressed when preparing the actual work.

Very different activities may be planned in woodland or green spaces. Maintaining vegetation above ground, removing roots, installing drainage, repairing a path and laying a utility line affect the ground in different ways. Describe what will actually happen on site. A general term such as grounds maintenance or reinstatement is often not specific enough.

Where possible, state where the work will take place and how deep the planned ground disturbance will extend. A route also needs details of lateral working areas, crossings and excavation locations. For individual positions, the proposed starting points and their location on the site are relevant. A clear drawing often explains these differences better than several general emails.

If the design changes, the survey documents must be checked against the revised project. Evidence for a narrow working strip cannot simply be extended to a wider area. The same applies to deeper excavations or new starting points outside the area previously considered. The report and construction design must describe the same working area, both in plan and in depth.

Historical aerial photographs can provide evidence of former site features and events. Together with maps and other records, they help locate areas of suspected ordnance. Interpreting them is specialist work: The date, image quality, coverage and visible changes must be considered. One image cannot explain the full history of an area.

Read the assessment with your project in mind. Which area was considered? What evidence was identified? Which areas remain unclear because of the available records? And what does this mean for the proposed work? These answers show what the images can establish for your project and which questions require further investigation on site.

Historical records answer different questions from a site survey. They can establish grounds for suspecting ordnance or narrow down the relevant area. A technical survey, in turn, relates to the local survey conditions and the agreed task. Together, they show what historical evidence exists and what the site investigation can establish about it.

Historical aerial photograph analysis for your project

A survey starts by establishing what work is planned in the woodland. For a path, the affected area matters; for a utility line, the route including crossings and excavations; for a borehole, the individual position and its depth. Existing evidence of ordnance is related to these working areas. This defines the questions a technical survey needs to answer.

Paths, uneven ground, vegetation and existing installations affect where survey instruments can be used. If parts of the site are inaccessible, this must be taken into account in planning. A quotation should therefore show which areas will be surveyed, the conditions that must be met and how areas left unresolved will be handled. The instrument's name alone does not define this scope.

When the design changes, the existing results are compared with the revised ground disturbance. An earlier survey can provide valuable groundwork. It applies, however, to the documented area and the task at that time. Additional path areas, relocated boreholes or greater depths must be considered separately before ground work begins.

Geomagnetics, electromagnetic methods and ground-penetrating radar investigate different physical properties. Geomagnetics records magnetic anomalies, particularly those associated with ferromagnetic objects. TDEM measures electromagnetic responses from conductive objects. Ground-penetrating radar records reflections from differences in the ground and can provide information about layers, buried installations and other structures.

An anomalous signal is initially a survey finding. Its position, the survey conditions and known buried installations are considered during interpretation. A point on a survey plan does not therefore establish with certainty what object is present. Depending on the findings, a further survey, a planned investigation of the target location or other specialist work may be required.

For planned woodland work, the report must show which areas were surveyed and which questions remain open. A survey along an accessible path does not automatically describe adjacent vegetated land. The depth range to which the results apply under the local conditions must also be clear. These stated limits form part of the findings and must be taken into account before the next ground works.

Ordnance survey methods and their limits

The visible surface alone does not determine whether a method is suitable. Ground composition, moisture and existing installations also affect the signal. Electrically conductive or highly heterogeneous ground can limit ground-penetrating radar investigations. Utilities, reinforcement and other metal objects can mask magnetic or electromagnetic signals. Method selection must take these local conditions into account.

The depth of the planned work is also decisive. A surface survey can assess only the zone for which it provides interpretable data under the actual conditions. If a foundation, excavation or utility requires a deeper working zone, the need for an additional investigation at depth must be assessed. A general depth claim without reference to the method, target object and area is insufficient.

Areas that cannot be investigated adequately must remain identifiable as such in the results. They must not be treated as showing no anomalies simply because no clear target signal could be recorded. This distinction matters to owners and designers: An area with interpretable survey data and a gap in coverage support different conclusions. The actual planned ground disturbance determines which further service can answer the outstanding question.

Maintenance, reinstatement and construction can overlap in woodland and green spaces. For an ordnance assessment, the relevant point is which activity actually disturbs the ground. A path, drainage system or new utility section may occupy a different working zone from the previous use. Individual boreholes and root removal must also be described by location and intended depth.

Geotechnical investigations, environmental investigations and ordnance assessments answer different questions. A ground investigation report may be important when designing a path or foundation. This does not make it an ordnance survey report. Equally, an ordnance survey does not assess load-bearing capacity or possible contaminants. The full reports and their agreed tasks show which services have already been carried out.

Coordination must take place before ground disturbance, especially for boreholes and trial pits. Designers, site management and the specialist contractor need the same information about the work location. If a report covers only an adjacent area, its relevance to the new work must be assessed. This keeps clear which questions have been answered and which further investigation is needed on site.

An earlier report can contain valuable groundwork. First establish what was commissioned, which area the report covers and what results it records. A heading or brief conclusion is not enough to apply it to a new project. Appendices, plans and information on areas not investigated can also be decisive.

Review these documents with those responsible for the project and the specialist contractor involved. Compare the task previously investigated with the new design. Where the area, depth and question agree, existing information can help with the next steps. Where they differ, the additional information or investigations required can be identified precisely.

File reports together with the correct version of their plans. Loose extracts without appendices can easily lose their original context. When passing records to a design office or contractor, provide the documents that belong together. New project participants can then see what was actually investigated and which limits the report states.

During an active fire, the responsible incident command decides how emergency personnel proceed. Others must observe cordons and official instructions. Carrying out your own investigations in the affected area is not part of preparing later maintenance or construction work. A private survey commission does not lift an existing closure.

For planned work, information about the property and project is gathered instead. The owner supplies existing records. The design identifies paths, working areas, routes or individual locations of ground disturbance. A suitable specialist contractor assesses which survey is appropriate for the task and documents the work performed. Site management needs the results before preparing the relevant work stage.

Official requirements are clarified with the competent authority. Which body undertakes which task depends on the project location and the specific circumstances. Pass on existing correspondence with its date, appendices and a clear identification of the relevant area. If a suspicious object is found during work, the immediate step is to notify the police. A technical enquiry about later surveys serves a different purpose from reporting an urgent find.

Dense vegetation, uneven ground, paths and existing installations affect how woodland can be surveyed. The specialist contractor needs to know which areas are accessible and where obstacles are located. Initially describe the site using existing plans and images already available. You do not need to enter potentially hazardous land or disturb the ground yourself to make an enquiry.

The preparation required and permitted is agreed in relation to the planned survey. This is particularly important when general terms such as site clearance or reinstatement can refer to very different activities. Vegetation above ground, roots and built obstacles affect the survey in different ways. State what is to be removed or changed rather than carrying out that work before the specialist assessment.

If part of the site remains inaccessible, this must be clear in the survey scope and later in the results. A surveyed area does not automatically include every space between the survey locations. Before later path construction, drainage or maintenance, any outstanding task can then be assessed precisely. Newly accessible areas are checked against the existing records; improved access alone does not extend a completed report.

Anyone planning paths, utilities or other installations in woodland needs the survey findings in time for the next work stage. The survey date alone is not enough. Interpretation, reporting and agreement on unresolved areas also form part of the programme. Together, they establish what the results show for the intended ground disturbance.

Agree when the designers and site management should receive the documents. The planned date for root removal, a borehole or a utility trench describes the need more precisely than a request for the fastest possible survey. Also identify which working areas are needed first and whether further sections will follow.

If new evidence emerges or the design changes, the relevant parties must be informed. A wider path or relocated starting point may extend beyond the area previously considered. Before work proceeds, establish whether the existing results are sufficient. This comparison must take place before ground works, so the work crew knows the extent actually surveyed.

For an initial enquiry, give FONTANA-EOD the exact project location and describe the planned work. A site plan with the working area marked, the proposed depths and the current design status help establish the requirements. Include any date or construction stage that has already been fixed.

Also provide existing aerial photograph assessments, earlier survey reports, known requirements and records of utilities or existing installations. Complete documents with their dates and appendices are helpful. If information is not yet available, say so in the enquiry. For example, explain if a survey has been mentioned but the corresponding report is still missing.

Describe the decision you need to make next. Are you preparing a tender, defining a survey scope or comparing existing results with a revised design? FONTANA-EOD can then identify which information is still needed for the forthcoming work.

Compile the project documents for your enquiry

A survey remains useful for later work only if its scope is clear. Keep the report, site plans and appendices together. They must identify the surveyed area, the task undertaken and the results. Inaccessible areas, survey limits and unresolved findings are equally important. A brief statement that the woodland was checked does not show these distinctions.

When paths are later altered, utilities added or different depths of ground disturbance planned, compare the changes with these records. The earlier survey remains a source of information. Whether it covers the new task depends, however, on where and under what conditions it was undertaken. A new plan should therefore clearly show how the proposed work differs from the previous design.

This also helps when responsibilities change. A new owner, another design office or a subsequent contractor needs the complete records for the relevant area. Passing on only a brief conclusion can lose the geographical limits and unresolved questions. The report and plan record what the findings actually apply to.

Understanding survey reports and clearance records

If you discover an object that could be ammunition, do not touch or move it. Leave the immediate area, warn others without putting yourself at risk and, in Germany, notify the police immediately on 110. Follow the instructions of the competent authorities.

Do not investigate the object yourself to make your report more precise. A closer inspection, cleaning or uncovering it can create additional dangers. Do not approach the find again for photographs or a more detailed description. Get yourself and others out of the immediate danger area; gathering more information does not justify approaching it again.

A project enquiry about planned work serves a different purpose from reporting an urgent find. It helps prepare future work and discuss the documents needed. For a suspected ordnance find, the police are the immediate point of contact. The following official guidance explains what to do if ammunition is found.

Official guidance on what to do if ammunition is found

Immediate help after an ordnance find

For a planned project, FONTANA-EOD needs the specific working area and proposed ground disturbance. Send a current site plan, details of the depth and working methods, and existing survey reports or official correspondence. The site's condition, access and known installations also help establish the requirements.

Identify the next activity: A path, utility line, borehole or other ground work. FONTANA-EOD works with you to establish what information is still missing and which survey task follows from it. If you have just found a suspicious object, contact the police directly.

Send a project enquiry to FONTANA-EOD

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