Technical map of the administrative district of Düsseldorf, marking Düsseldorf as a location for ordnance investigation and surveying by FONTANA-EOD

Ordnance assessment in Ratingen: clarify ground interventions on existing sites

What groundworks are added by your alteration? New foundations, deeper utilities or an extension may exceed the area previously investigated. FONTANA-EOD supports commissioned assessment in Ratingen of the investigation needed for this work. We compare documented existing conditions with planned construction. A change of use without groundworks is considered separately.

Existing building space

Compile as-built plans and earlier reports.

New areas and depths

Mark additional groundworks in the design.

Coordination with the town

Clarify the application and necessary measures for the project.

Discuss groundworks for alterationsExplosive ordnance assessment in North Rhine-Westphalia
Assess the construction project

The actual alteration work determines further needs

A new use may involve additional ground interventions or leave existing building space unchanged. For your Ratingen project, we compare existing conditions and planned construction. Existing ordnance documents are related to the specific changes; outstanding questions are clarified before affected work.

Project references

Selected project examples

Project site

Connect the site with the specific construction task

Illustrative map of North Rhine-Westphalia with the state coat of arms, a tablet, a white FONTANA-EOD helmet and a notebook.

Consider Ratingen's procedure and the actual alteration together

The town of Ratingen routes the aerial photograph analysis application through the local public order authority to the Düsseldorf explosive ordnance disposal service. It identifies certain cases where this application is not to be submitted. Compare the conditions described with the actual work; the term conversion alone does not replace this comparison.

Property identification links the address, cadastral plot and current site plan. Ground interventions belonging to the alteration are additionally identified with their extent and depth. Existing reports retain their own spatial reference. For several buildings or construction phases, clearly record which document addresses which work area. A project in another municipality follows its procedural route. A shared property name does not combine separate investigation areas into a new overall result. Further project locations are listed in the regional overview.

The overview of the Düsseldorf administrative district provides further local information for the regional context of your construction project.

North Rhine-Westphalia
Local context

When actual construction work is decisive for the application

Check Ratingen's scope against the actual work

Ratingen's service portal describes the aerial photograph analysis application and identifies cases where it is not to be submitted. These include work without ground intervention and changes of use or demolition under certain conditions. Check these conditions against the actual construction. The terms alteration or conversion alone are insufficient.

The chronicle of the town of Ratingen describes the heavy air raid on the town centre on 22 March 1945 and subsequent rubble removal and construction. For a property, earlier buildings and later ground changes are considered with their actual locations. Suitable historical images, construction files and ground level plans are researched and assessed by specialists. They may help trace earlier construction conditions and later ground interventions. The specific outstanding ordnance question is derived from these together with today's plans.

Compare existing conditions with new plans

Compare existing conditions and the design: does the work stay within the existing building space or add new areas and depths? If an older document describes only the former construction condition, its finding cannot automatically be transferred to changed plans. Clarify uncertain cases with the local public order authority.

A larger basement, new foundations, additional retaining structures or changed connection areas may extend beyond the area previously considered. For an alteration, describe whether the building volume changes and what additional ground interventions arise. Documents on reconstruction, demolition, fill or later extensions are considered where they describe the area affected. The local public order authority receives the actual scope. Conditions of any specified procedural exception are compared with this construction work. Specialist planners use earlier results within each documented area.

Working together

Distinguish the tasks of client, designers and specialist contractor

Client and operator

For the alteration, the developer identifies building parts remaining in use and volumes of ground to be changed. They provide existing-condition files and earlier ordnance documents. During ongoing operations, the operator adds accessible routes, use times and conditions for work on existing installations. A named contact collects missing information; responsibility for obtaining it remains explicitly assigned. Before the specialist commission, record which additional ground intervention needs a decision and who provides the necessary documents.

Planning and construction management

Specialist planners compile existing and new foundations, utility connections and working areas in distinguishable plan versions. They identify the location, depth and construction method of every change. Site management assigns contractors and agreed specialist work to these interventions. If a connection is later planned deeper, for example, ordnance specialist planners receive the changed version before construction. A contractual lot boundary is treated separately: whether it is also an investigation boundary follows only from associated reports and plans.

Specialist company and competent bodies

The private explosive ordnance specialist carries out the agreed investigation and documentation work. Requirements and decisions of public authorities are addressed with the responsible bodies. The documents needed for a particular procedure depend on the location and project. The technical report describes the work carried out, including its documented area, depth and scope. Decisions reserved for public authorities are made by those authorities.

Ratingen's local public order authority advises on application documents and forwards the aerial photograph analysis application to the state explosive ordnance disposal service at the Düsseldorf District Government. The public order authority decides on further measures needed from the specific process. Permissible private specialist tasks are agreed with their investigation and documentation scope. Changes to existing conditions and additional groundworks are shown completely during coordination. For project locations outside Ratingen, local responsibility follows the actual address. A need for ordnance recovery is coordinated with the permissible task and the competent authorities.

Investigation task

Which specialist task comes next?

Clarify applicability with the town

Ratingen's service page distinguishes particular activities and their conditions. Describe actual ground interventions for assessment. A general work description is insufficient. Discuss uncertain cases and changes with the local public order authority using the specific design.

Assess historical documents

Limit an addition to the new question

Existing results and additional ground interventions identify the finding still missing. Further investigation is planned with the technical conditions on the existing site. Not every change needs the same approach. Before a private commission, also consider the North Rhine-Westphalia prerequisites and official requirements applicable to the specific activity.

Compare investigation methods
Project types

Describe alterations and additional ground interventions precisely

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

Record construction changes individually

The project label alteration does not describe what work will actually take place. Identify new foundations, utility sections or other ground interventions with their location and depth. Preparatory activities are included too. Specialist assessment follows these details, rather than the building's eventual use alone.

Provide specialist supervision of excavation
Illustration: two people review plans and documents at a table beside a construction vehicle.

Evidence existing boundaries through documents

Comparison needs as-built plans and earlier reports with their respective status. Unknown depths or undocumented structures remain expressly unresolved. An assumption about earlier groundworks is not used as an established investigation boundary. Missing details are clarified specifically before a decision based on them.

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

Show utility changes traceably

Compare previous and planned routes, and the width and depth of the work. Work described as renewal may affect additional areas. Mark these differences on the current plan. Existing results are assigned according to their actual findings, rather than the previous utility label alone.

Specialist services and investigation tasks
Preparation

Prepare the scope and commission together

Before commissioning, compare existing conditions and planned groundworks with existing ordnance documents. For the Ratingen project, define the finding still needed, official procedural status and permissible specialist task.

Establish what needs to be known before commissioning the work

For an alteration in Ratingen, compare existing use with groundworks actually needed. An additional basement raises a different spatial question from unchanged use within an existing building. Provide the previous floor plan, new design and available result plans together. The commission defines whether documents first need assessment, additional areas need investigation or assessed findings need further work. Each task receives the information and result documents needed; location, depth and state of knowledge are explicitly identified.

Define the specialist task

Coordinate preparatory work with the investigation

In an occupied building, a survey area may become accessible only after access has been agreed. Plans therefore record which rooms, external areas or utility sections will actually be available on the investigation date. Utility information and other trades' work relate to this. The selected method determines necessary survey conditions and preparation. Breaking out, exposure or other preparatory ground interventions are agreed with specialist and organisational input beforehand; they are treated as separate work even if intended only to provide later investigation access.

Clarify preparatory work in the programme

Agree a clear scope and schedule

Agree the date for an identified working area and documented plan version. If the extension area is accessible but the utility connection remains closed, for example, record this division in the commission already. Identify for each part when an interpreted result is needed and what prerequisites remain outstanding. The sequence accounts for fieldwork, assessment and handover. Effort and dates follow this scope, access, documents and execution conditions; the next construction decision is aligned with the result status actually available.

Discuss the scope and schedule
Tasks at the site

Changes to include in construction documents

01

Groundworks for the new use

Describe construction work needed for the new use, such as utility trenches or new foundations. List these activities individually; the new use alone does not establish whether or where the ground is affected.

02

Extension of existing building space

Place as-built plans and the design side by side. Mark where the new construction extends beyond the existing building or documented groundworks. Even small additional areas must be locatable on the plan. Results for adjacent existing structures do not automatically cover them.

03

Changed utility location or depth

For utility work, state whether route and depth remain unchanged. A changed route, widening or deepening must be included in plans and coordination. The term renewal alone does not describe the groundworks actually planned.

04

Missing existing-condition information

Explicitly identify missing existing-condition details. If an earlier intervention depth is not evidenced, it must not be used as an established boundary. The outstanding question can then be clarified specifically before affecting investigation planning.

Project documents

Documents that establish the next step

Read the earlier report with its original purpose

Record the construction condition and ground intervention for which the document was prepared. Associated annexes often show the decisive spatial boundaries. A result for existing conditions is not transferred to new work solely because the address is the same. Comparison considers the task, depth and identifiable limitations.

For a change of use, Ratingen's service portal identifies two combined conditions: the building volume remains unchanged and there is no ground intervention. For the demolition described there, the boundary of the previously enclosed building volume is decisive. A new basement or additional utility trench is therefore shown expressly. For what the town calls “Leitungen des ehemals offenen Verbaus”, installation after 1945 and an unchanged route without widening or deepening also apply. Existing-condition documents must support this assessment. For missing information or changed work, clarify the specific construction with the local public order authority. The terms conversion, demolition or renewal alone do not evidence the prerequisites.

For the application, Ratingen's service portal describes an extract from the Deutsche Grundkarte at a scale of 1:5000 with unambiguous marking of the areas to investigate. A comparable suitable map may support spatial assignment. The marked boundary is linked to the specific construction project. For several plan versions, it remains clear which accompanied the application and which changes were added later. Additional intervention areas and depths are compared with existing information and reports. The next specialist question can then address the working area actually planned.

Hand over the new construction plans with applicable results

Site management receives the current design with ordnance documents usable for it. Identify added areas and clarification still outstanding. Earlier versions remain identifiable as such. A further plan change is checked before affected work so documented findings continue to fit actual construction.

At handover, record which results fit existing conditions and where questions remain. The result plan identifies the area actually investigated and relevant limitations. Site management receives the report, maps, current design and associated official information together. Significant differences remain clear even in a short overview. For another plan change, repeat this comparison before affected groundworks. Identify those responsible for missing documents, additional specialist work and coordination of next steps. After clearance work, the clearance record with its scope, results and remaining limits is assigned to the area actually treated and associated plan version.

Construction sequence

Coordinate investigation and construction sections

Before tendering alteration work

Compare existing conditions and planned ground interventions with clear plan versions. Include earlier information and reports in full. Identify unresolved questions so they can be considered in the next commission. A generally worded service item does not replace assignment of actual new working areas.

Coordinate the construction phase with us

For a change during construction planning

Communicate additional areas, greater depths or another construction method in good time. The changed part is compared with previous results. Outstanding prerequisites are clarified before its construction. A different section already agreed does not automatically confirm an intervention added later.

Coordinate the construction phase with us
Method selection

Select methods according to the task and survey conditions

Historical records and aerial photographs

For comparison with existing conditions, historical images and older documents are assigned to the earlier building footprint and newly planned working areas. Image availability, interpretability and coverage are decisive. Aerial photograph analysis can assess indications of wartime impacts for this area and support further investigation planning. The absence of a visible indication is distinct from technically investigated ground. Changes through demolition or reconstruction are compared with today's construction files. Historical analysis describes the image content at the time; measurements of today's subsurface and findings about later ground interventions each need their own specialist basis.

Understand aerial photograph assessment

Magnetometric survey

Magnetic methods detect magnetic anomalies. For an alteration, suitability for expected objects, ground conditions and the investigation area needed is checked alongside existing structures. A fence beside the extension, utilities at a connection or metallic existing components may affect measurement and interpretation. These conditions are assigned to the working area concerned, rather than inferring the entire site's status from a neighbouring area that surveys well. Signal strength alone does not identify explosive ordnance. Planning therefore links suitable measurement, specialist assessment and necessary further clarification for the actually new ground intervention.

Understand the scope of magnetometry

Electromagnetic methods

Electromagnetic methods may suit appropriate metallic targets and site conditions. For renewal of an installation, first describe which installations remain and which additional volumes of ground need investigation. An instrument name is insufficient: specialist planners justify suitability according to the finding required, accessible survey areas and possible interference. Locations and investigation conditions are documented with results. Whether a second method is needed follows from interpretation of the specific connection or extension area and the question still outstanding there.

Understand electromagnetic surveying

Ground-penetrating radar

Under suitable conditions, ground-penetrating radar provides information about subsurface structures and reflections. For an alteration, clarify whether an existing radar report was intended to investigate utilities, structures or the ordnance question. Ground conditions, moisture and installations affect interpretability. An identifiable foundation may help planning around existing structures; it does not answer the ordnance question for an additional volume of ground. Both anomalous and unremarkable images are interpreted only within the respective specialist task. The commission, actual area and depth findings covered, and limits are documented for comparison with the new construction.

GPR and limitations

Deep-ground and downhole surveys

A deeper foundation or utility may extend beneath an earlier investigation area. Specialists then check whether a surface investigation still addresses the required objective or a deep-ground or downhole survey is needed. The commission needs location, depth, planned boreholes and existing utility information. Creation of investigation access is also prepared by specialists. A standard grid or general depth figure does not replace planning for this volume of ground. Later findings relate to the method actually used and documented investigation areas.

Prepare deep interventions

Survey during construction

For work on existing sites, part of the subsurface may not be fully accessible or interpretable beforehand. Specialist planners then assess whether an approach accompanying construction is suitable for that specific area. It describes investigation steps, interpretation and communication of findings together with the planned construction work. Merely watching excavation does not replace a necessary survey. Site management needs coordination by section: when specialist work takes place, how new findings are passed on and which areas remain unresolved pending further clarification. This defines the scope of commissioned supervision.

Agree the approach during construction
Technical assessment

Check whether existing results cover the new work

Compare earlier information with the design

The historical aerial photograph analysis must fit the application area and intended construction work. Read existing information with its annexes. A result for the previous construction section need not also cover an extension area or deeper work.

For each older report, compile the task, date, area covered and associated annexes. Relate current plans to the same spatial reference. If the investigation level or depth information is unclear, clarify the details needed from the complete documents. An earlier construction plan shows the design at that time; the investigation report describes specialist work actually performed. For differences, record which finding already exists for the new construction and what addition is still needed.

Check access and survey conditions

Whether and how a survey is possible and suitable also depends on existing conditions. Structures and metallic installations may affect access and measurements. These conditions belong in investigation planning. The size of the intervention area alone does not establish a suitable method.

In existing buildings, foundations, reinforcement, utilities and other installations may affect measurements. Access and accessible working areas are therefore described before defining the service. Method selection considers ground conditions, targets, intervention depth and interference. A suitable investigation and specialist interpretation belong together. Areas with restricted interpretability remain documented within their actual scope. A supplementary investigation step addresses the finding still needed and is agreed subject to applicable prerequisites.

Describe the commission scope

The clearance plan or the investigation plan describes the area and investigation objective. Identify additional questions and record which existing parts are outside the commission. The later report must identify which tasks were actually undertaken.

The task description separates existing structures from additional ground interventions. A new foundation may also involve working space, excavation support or preceding utility work. For comparison, show these areas with their depths and elevation references. A new construction phase uses applicable results within the documented scope. Larger working areas, changed foundations or different depths are considered separately before construction. Site management receives complete result documents and outstanding tasks for the section affected.

Next steps

Agree changes before groundworks start

01

Initial contact and assessment of the evidence

At first contact, describe existing conditions, new groundworks and the decision needed. Earlier plans, ordnance reports and official notifications are compiled in full with dates and annexes. If historical information is missing, the necessary aerial photograph analysis is initiated through the local public order authority. For unresolved use or ground information, supplementary records and images are researched and assessed by specialists. Findings are linked to the specific construction intentions.

02

Coordinate changes and methods

The current plan identifies additional areas, depths and construction methods compared with existing conditions. The suitable investigation method is determined according to ground conditions, targets, interference and access. Changed work is coordinated with the local public order authority. State measures and permissible private tasks are assigned to their respective responsibilities. Preparation and missing existing-condition details are clarified before execution. Everyone uses the same identified plan version for questions.

03

Investigate and assess results

The agreed survey or suitable supplementary specialist supervision is undertaken under the defined conditions. Measurements and observations are interpreted by specialists and assigned to areas addressed. Assessment distinguishes usable findings, anomalies and locations with restricted interpretability. Differences from previous knowledge or agreed scope are documented and communicated to specialists involved. Further investigations needed follow from outstanding questions about the specific construction.

04

Document findings and prepare the subsequent decision

Site management receives results and conditions for the agreed work with maps and annexes. Investigated areas and unresolved extension areas remain distinguishable. Before construction, the current design is compared with documented scope and official status. New plan changes are checked separately before affected ground interventions. Applicable existing results remain usable for their covered area. Specialist additions and decisions still needed are assigned to each construction section.

Documentation

Relate earlier results to additional ground interventions

Document existing conditions and new investigation scope together

The report must identify the investigated area, depth considered and investigation conditions. For an alteration, check how these details fit the new construction. Uninvestigated extension areas remain labelled as such. They do not form part of the result merely because they share the property address.

Project responsibilities

The BFR Kampfmittelräumung describe specialist work on federal properties and provide specialist guidance for planning and documentation outside their direct scope. In Ratingen, North Rhine-Westphalia responsibilities remain decisive. The technical report documents the specialist service performed within its spatial and technical limits. Competent authorities make official decisions.

Working approach

How FONTANA-EOD works

Document the agreed specialist service clearly

For the alteration, FONTANA-EOD addresses the agreed ordnance question for the groundworks identified. The basis is compared existing conditions, new plans and the permissible specialist task. Before construction, define accessible investigation areas and results needed. If the basement footprint or route of a connection changes, for example, compare the affected part with the commission. The report then identifies the investigation actually performed and its limits. Site management can identify which finding fits the original conditions and what still needs clarification for the changed ground intervention.

Discuss the investigation task

The task before the equipment

First identify the finding still missing: is earlier information to be assessed, an extension area investigated or a deeper connection evaluated? Select the method from this under actual site conditions. An available instrument or approach on a neighbouring site does not itself justify a suitable investigation. The specific specialist question remains linked to the new ground intervention in the commission.

Keep limitations visible

If part of a basement is inaccessible or a connection zone has restricted interpretability because of installations, identify it separately on the result plan. The overview shows the proportion actually investigated and outstanding question. Site management can then agree suitable further investigation for the next section. A total area figure is supplemented by these limitations so existing conditions addressed and the unresolved extension remain distinguishable.

Clarify changes before intervening in the ground

A wall moved outwards, deeper foundation or different construction method is compared with existing results. Responsible specialist planners receive the change before affected groundworks. They clarify whether the previous finding still fits or an addition is needed. Even under the same project name, the change remains traceable in the task overview with location, depth and specialist response.

Hand over the report and plan together

For handover to new site management or a specialist contractor, provide the result plan, complete report and current alteration design as related documents. A short overview can point to applicable annexes and unresolved areas. Their spatial findings continue to follow from the documented investigation. Across several construction sections, it remains clear for which specific work the new participant can use the results and which question needs further clarification first.

Understand the results

Use technical statements for the next decision

An existing building does not evidence a complete investigation

Buildings alone do not establish which areas were investigated earlier. The reports and annexes from that time are needed. Long use does not extend their evidential scope either. New ground interventions are assessed using traceable results, and remaining information gaps are explicitly identified.

Understand investigation reports and their limitations

Distinguish unchanged purpose from unchanged construction

An installation may retain the same purpose while its utility route, depth or structures change. Conversely, use may change without new groundworks. Actual construction is decisive for specialist assessment. Show the specific differences rather than summarising them only under a general project title.

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 alterations and renewed installations in Ratingen

Does every change of use need a new aerial photograph analysis?

Ratingen's service page identifies cases where this application is not to be submitted. These include changes of use without changing building volume and without ground intervention. Compare current conditions with your actual work. If groundworks are added, the work must be reassessed accordingly. Coordinate assessment early before affected groundworks so necessary applications and investigations fit the construction programme.

Is an older report sufficient for an additional foundation?

Check whether the report covers the new foundation's location, depth and construction method. Compare annexes with the current design too. A result for the existing building does not apply to a previously uninvestigated area without specialist review. Method suitability depends on ground conditions, targets, depth and interference. Areas that cannot be interpreted or have restricted interpretability remain documented.

What details matter for a changed utility?

State previous and planned routes, depth and construction method. Mark changes and missing existing-condition information. This allows assessment of which existing results still fit and which questions remain for the new utility.

Who decides on necessary further measures?

According to Ratingen's procedure, the local public order authority decides on necessary measures. FONTANA-EOD undertakes agreed specialist tasks within the commission. A private investigation does not replace that official decision. The sequence links document review and necessary historical analysis with method selection, investigation or suitable supervision, assessment and documentation. Before the next construction work, compare results with the current ground intervention.

What should you do if a suspicious object is found?

Stop work in the affected area, do not touch or move the object and move away. Keep other people away and notify the police immediately on 110. Follow the authorities' instructions.

Does an existing building evidence investigation of its surroundings?

No. Existing reports, annexes and their actual scope are decisive. The building alone contains no documented finding for additional areas.

Which factors determine effort and costs?

The method, investigation scope, depth, interference and access determine the effort required. Incomplete as-built documents, additional working areas or supplementary investigations affect the steps needed. Preparatory, accompanying and follow-up work are considered in the specific process. The service agreement describes the permissible specialist task and result documents needed. Those involved clarify their tasks and associated cost responsibilities before execution.

What matters if a utility keeps its use but is installed deeper?

The new depth and actual working area are compared with previous documents. Unchanged use does not replace specialist assessment of the changed ground intervention. This needs as-built plans, the current design and complete earlier ordnance documents with annexes. Known gaps and unresolved existing depths remain expressly identified.

Project enquiry

Prepare your alteration in Ratingen

Compare existing conditions with the design

Send identified plan versions with additional areas, depths and construction methods. Add the project address, cadastral plot, construction phase, schedule and decision requested. Planned depths have a clear elevation reference. The sector overview explains typical interventions and the documents they require.

Identify gaps in knowledge

Include complete older reports and identify existing structures or earlier intervention depths not supported by evidence. Identify the groundworks due first and contacts responsible for further information.

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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