Technical map view of the Cologne administrative district with Cologne marked for explosive ordnance investigation and surveys by FONTANA-EOD

Explosive ordnance assessment in Troisdorf: Prepare access and documents

Can the proposed investigation area be entered, and are the necessary permissions in place? FONTANA-EOD supports clients, specialist planners and site management in Troisdorf with the commissioned preparation of explosive ordnance investigations. We compare site plans, existing knowledge and available areas with the proposed task. Permission to enter governs access; whether and how investigation is possible is additionally clarified on technical grounds.

Property and project

Compile the site plan and proposed groundworks.

Access to the area

Clarify necessary permissions with owners.

Areas still closed

Assess effects on the investigation.

Prepare the investigationExplosive ordnance assessment in North Rhine-Westphalia
Assess the construction project

Make the areas required available before the appointment

An investigation may require additional access or neighbouring areas beyond the construction area itself. For your Troisdorf project, we compare the proposed task with the areas and documents available. Permissions, technical prerequisites and outstanding areas are each considered according to their own purpose.

Project references

Selected project examples

Project site

Connect the site with the specific construction task

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

Relate Troisdorf's requirements to the actual area

Troisdorf is in North Rhine-Westphalia, within the Rhein-Sieg district and the Cologne administrative district. The municipal enquiry is processed by the city's Ordnungsamt; the state explosive ordnance disposal service for the Rhineland is based at the Düsseldorf district government. For local investigations required, permission to enter is clarified with the owners concerned, including neighbouring properties needed. The project location, actual investigation area and access required are therefore identified together. Further specialist tasks and official decisions are coordinated with the respective responsible parties.

North Rhine-Westphalia
Local context

Which documents Troisdorf identifies for the enquiry

Application documents and permissions in the Troisdorf procedure

The City of Troisdorf's service portal requires explosive ordnance enquiries to include the precise property location and use, together with a marked extract from the official base map. Where on-site investigations are required, owners' permission to enter is envisaged. This also applies to neighbouring properties if they must be entered for investigation. The written application is submitted to the Ordnungsamt; the city also offers an online service. It recommends submitting the enquiry at least half a year before construction begins. Existing analyses for the area are checked first. Where no analysis exists, historical aerial photograph analysis by the state explosive ordnance disposal service is envisaged. For the application, the city explicitly identifies the official base map at a scale of 1:5000 with the property clearly marked. Any former federal ownership and use is also stated. Documents are related to the area actually applied for.

Distinguish access, utility information and the specialist task

For surveys required, the city also identifies an overview of utilities. The application, utility plans and permission to enter serve different purposes. In addition, technical assessment must establish which area can be investigated under existing conditions. The city explains that utility plans can be obtained from the respective utility operators and supplied later if necessary. Preparation records which information is already available and which remains outstanding. Permissions required are assigned to the properties actually to be entered and the respective contacts. If the area required changes, this allocation is updated too. In its notice of 23 October 2024, the City Archives commemorates the air raid of 29 December 1944. For present-day projects, historical documents are checked against the specific property and proposed ground interventions.

Working together

Distinguish the tasks of client, designers and specialist contractor

Client and operator

The project owner describes the proposed work and provides the available project documents. The operator adds requirements for use, access and timing. A coordinating contact makes cooperation easier but does not automatically take on every other party's duties. Before commissioning, record 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 scope. Official requirements and decisions are clarified with the competent authorities concerned. The documents needed for a particular procedure depend on the location and project. The technical report describes the specialist service performed; its conclusions are not presented unchecked as general authorisation for further groundworks or as an authority's decision.

Investigation task

Which specialist task comes next?

Assess access and investigability separately

An accessible area may have technical limitations. Utilities, buildings and other installations are therefore additionally considered. Permission to enter does not establish a suitable survey method. Selection follows the actual specialist question, existing knowledge and conditions within the work area.

Assess historical documents

Describe the scope required before agreement

Compare proposed groundworks and available documents with the investigation areas needed. Missing access may affect the findings achievable and is identified explicitly. The service is defined with these prerequisites. Official determinations and the legal prerequisites for the specific private activity in NRW are also checked.

Compare investigation methods
Project types

Clarify availability for the specific investigation task

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

Describe all access required

The route to the work area may cross other properties or operational areas. Show the areas actually needed for the proposed activity. Identify the respective contacts. Consent for the construction area is not transferred to an additional access route or neighbouring area without clarification. Draw the vehicle access, proposed setup areas and subareas to be investigated on the same site plan. Property boundaries remain identifiable on it. Identify necessary passageways and usable access times. The specialist company can then assess the investigation volume actually available and prerequisites still requiring clarification before the appointment.

Coordinate the sequence and tasks
Illustration: two people review plans and documents at a table beside a construction vehicle.

Assign permissions to the correct area

A declaration should be linked to the area for which it was given. Keep the associated site plan and any conditions together. Unclear boundaries are clarified before work. The spatial reference of a permission must not emerge only from a casual verbal description during the appointment. Assign each property concerned the declaration required and the person with whom access is coordinated. Spatial or time conditions are passed on with the current plan. For subsequent work, it is clarified who provides the agreed access and notifies the parties involved of changes.

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

Report changes in availability in good time

If an area promised earlier has since been closed, built over or used differently, this affects preparation. Communicate the change with its precise area and expected duration. The investigation sequence is then coordinated accordingly. An earlier commitment does not demonstrate that the area is actually available on the proposed day.

Coordinate the sequence and tasks
Preparation

Prepare the scope and commission together

The following specialist topics explain possible investigation tasks. Which activity may be privately commissioned under the specific North Rhine-Westphalia procedure is clarified separately before an agreement.

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 sound workflow distinguishes work already clarified technically from outstanding prerequisites. If an area will be accessible only in part, commissioning must take this into account. Handover and assessment of results also need time in the construction sequence. An enquiry therefore does not imply a blanket commitment on dates or cost. Specific coordination connects the described scope with access, documents, execution conditions and the date by which a decision is needed.

Discuss the scope and schedule
Tasks at the site

Clarify access, contacts and available dates

01

Investigation areas and access routes

Draw where investigation is intended and which areas must be accessible for it. State whether neighbouring properties are required. The basis is the specific investigation task; the property address alone does not describe the access needed.

02

Owners and contacts

Clarify who can provide the areas required and give the necessary declarations. An arrangement with site management does not automatically replace the owner's declaration. Even with permission to enter, survey conditions and permissible groundworks must be assessed separately.

03

Availability within the construction programme

Coordinate when the area will be available and which other works take place there. If subareas become available consecutively, investigation planning must be adapted accordingly. Clarify the other investigation prerequisites before the appointment too. Consider use by other companies, deliveries and temporarily occupied access routes. The respective employers incorporate proposed activities and their interfaces into the risk assessment. Changed time windows are communicated with their reference to the work area required. Preparatory tasks needed are coordinated with their commission, responsibility and proposed timing.

04

Inaccessible subareas

Tell us if an area required is closed or cannot be used as proposed. Have its implications for the investigation assessed. An area not addressed must remain identifiable as such in the report later.

Project documents

Documents that establish the next step

Bring permission and the specialist commission together

Authorisation to enter describes a prerequisite for the work. The specialist commission, by contrast, establishes which question is addressed and to what extent. Both documents must fit the actual activity. Permission for an official procedure is not treated as a general private commission or an investigation result.

Keep unavailable areas identifiable in the result

If only part of the proposed area could be addressed, this is documented. Site management receives the location of outstanding areas and the questions remaining as a result. A shared appointment or property name does not conceal this limitation. Specific needs for further work are coordinated with the parties involved.

Documentation identifies whether an area remained outstanding because of missing access, site obstructions or technical method limitations. Causes are assigned to the subarea concerned and proposed construction task. If an initially closed area becomes available later, the new condition and investigation still required are coordinated before the groundworks concerned. The client and contractors receive the relevant result and plan revisions for this.

The investigation report assigns the initial data and historical documents used, together with survey data, survey results and assessment of findings, to the site plan of the cadastral parcels, routes or construction areas concerned. After clearance work, the clearance record with the actual clearance scope and results is attached. The conclusion records which findings are usable for the approaching construction task and which steps are still missing for outstanding subareas.

Construction sequence

Coordinate investigation and construction sections

Before coordinating the on-site appointment

Compile the site plan, proposed interventions and permissions required. Identify areas not yet available and information still outstanding. The parties can identify unresolved preparations from this. An agreed appointment is not treated as a substitute for missing consent or an unresolved technical prerequisite. The city identifies vegetation clearance, removal of surfacing or structures, and setting out borehole positions among possible preparations with cost implications. Whether such work is necessary and permissible for the specific investigation is clarified before commissioning it. Relevant explosive ordnance knowledge, protection requirements and responsibilities are considered. State which preparatory works are already documented and which are merely proposed.

Coordinate the construction phase with us

For an investigation in several sections

Assign each section the areas and documents actually available. Keep areas already addressed separate from those still outstanding. A partial result is passed on within its documented scope. For later sections, plan changes and different conditions are reconsidered before the respective construction work.

Coordinate the construction phase with us
Method selection

Select methods according to the task and survey conditions

Historical records and aerial photographs

Historical aerial photograph assessment and other old records help place the basis for suspicion in its spatial context. The available images, their evidential value and the limits of the area considered matter. The absence of an identifiable indication must be distinguished from a technically surveyed ground area. The assessment is considered together with the planned intervention and other available findings. It can support the choice of a survey, but is not a measurement of the present-day subsurface or confirmation for all future works.

Understand aerial photograph assessment

Magnetometric survey

Magnetometric methods detect magnetic anomalies. Whether they can address the specific survey task depends, among other things, on the expected objects, ground conditions, interference and required survey area. Fences, utilities or existing structures may affect interpretation. A measurement signal is therefore not described as ordnance solely because of its strength. Method, interpretation and any further investigation are planned as a connected specialist task.

Understand the scope of magnetometry

Electromagnetic methods

Electromagnetic investigations can be suitable for particular metallic targets and site conditions. Their suitability must be explained for the task, rather than inferred simply from the availability of equipment. Interfering installations, accessible areas and the findings required must also be considered. Results are documented with their location and survey conditions. The specialist assessment determines whether a supplementary method is needed; this remains a project-specific decision.

Understand electromagnetic surveying

Ground-penetrating radar

Under suitable conditions, ground-penetrating radar can provide information about subsurface structures and reflections. Ground conditions, moisture, installations and the particular survey task affect interpretability. An anomaly is not automatically ordnance, and an area with no apparent anomalies is not general evidence for arbitrary depths. The specialist interpretation and its limits are documented with the instruction. A survey for another purpose is not adopted without checking as ordnance evidence.

GPR and limitations

Deep-ground and downhole surveys

For deeper interventions, it may be necessary to assess whether investigation from the surface can provide the findings required or whether another approach is needed. Location, depth, borehole layout and existing utilities then form part of preparation. Creation of investigation access must also be planned in a technically suitable way. A general depth figure or standard grid does not replace this task. Results remain bound to the areas actually addressed and method used. For borehole positions, actual starting locations and elevations are shown together with intervention depth. The explosive ordnance findings required are determined before intervention. Available access and working spaces are related to the specific proposed positions.

Prepare deep interventions

Survey during construction

If a necessary preliminary investigation cannot be completed, the specialists assess whether a planned approach during construction is suitable. This includes coordinated investigation, interpretation and communication of findings within the intended work sequence. Visual observation of excavated material is not an interchangeable substitute for a necessary survey. Site management needs a clear description of when specialist work will take place, how new findings will be handled and which areas remain unresolved.

Agree the approach during construction
Technical assessment

An accessible area is not automatically suitable for surveying

Determine the investigation required

The historical aerial photograph analysis and further documents help determine the investigation needed. Planning also requires the location and depth of the proposed groundworks. An easily accessible area is insufficient if the actual construction work lies elsewhere or additional areas need investigation.

Consider utilities and installations

For a survey, survey conditions must be assessed as well as access. Utilities, buildings and other installations may affect the method. Preparation required and permissible is clarified for the specific project with the responsible parties.

Record uninvestigated areas

If the proposed scope cannot be achieved, the clearance plan or investigation plan must be adapted. Outstanding areas may require separate work. Time pressure or a more easily accessible neighbouring area does not remove the technical limitation.

Next steps

Prepare the on-site investigation

01

Compile the application and earlier documents

Compile site plans, correspondence and existing investigation results. Identify what has already been submitted and what has been added. The current investigation commission can then be compared with the original enquiry. The initial project enquiry discusses the construction task, areas, depths and next decision required. Demolition, connections and temporary construction stages are considered alongside new buildings. Known utilities and the respective current plan revision are allocated.

02

Coordinate access with owners

Clarify access and declarations required using the same area boundary as for the investigation. Record the areas to which a commitment applies. Unclear area descriptions should be resolved before on-site work. Information, aerial photograph analyses and investigation reports are checked for plan revision, spatial coverage, depth reference and outstanding questions concerning the present task. The scope actually documented is decisive. Missing or contradictory information is identified with its reference to the proposed intervention.

03

Supplement historical information

The required state aerial imagery analysis is initiated through the municipal procedure provided locally. If the available findings need supplementation, further historical research is carried out for the specific question. Available aerial imagery, maps and records of use are professionally analysed and related to the present-day construction site. The findings feed into further investigation planning.

04

Communicate changes before the appointment

Before the investigation appointment, check that the agreed conditions still exist. Report closed, built-over or otherwise unavailable areas. Document changes and coordinate the investigation adjustments required. The specialist company selects the technically suitable approach according to the investigation objective, basis of suspicion, ground structure, interference and accessibility. Preparatory services and the permissible activity scope are clarified. Investigation areas and interfaces are coordinated with the construction sequence.

05

Investigate and assess results

Within the agreed and permissible scope, the defined areas or points are investigated using a suitable method. The data collected are recorded with location, depth reference and site conditions. Specialist personnel assess results and anomalies according to the investigation objective, method and interference. A measurement anomaly is not yet identified ordnance. Further clarification required and areas not adequately investigated are identified; local reporting procedures apply if ordnance is found.

06

Hand over addressed and outstanding areas

After investigation, record which areas were addressed and which limitations existed. Pass this information to site management with the results. Omitted areas thus remain identifiable in further planning. Work carried out and its technical assessment are documented in a report with associated site and plan appendices. Methods, areas addressed, depth references and limits of findings remain traceable. The client and designers check this status against the next construction phase. Additional specialist work or official steps are identified before the interventions concerned.

Documentation

Retain permission to enter separately from investigation results

Findings and their scope

File land-use declarations, survey data, reports and official responses separately and assign them to the respective area. It must remain clear who made which statement. Permission to enter is not an investigation result and does not confirm the safety of all proposed groundworks. Hand reports over with their associated maps and appendices. A document overview identifies issuer, date, spatial reference and contents. Different names for the same subarea are allocated traceably on the current site plan. For later construction sections, the investigation belonging to each commission and the result status supporting further planning remain identifiable. Missing appendices are passed to the responsible project participants as outstanding information.

Project responsibilities

The BFR Kampfmittelräumung provide technical guidance for preparation and documentation. Local procedures and the limits of private tasks under the KampfmittelVO NRW must be observed. FONTANA-EOD provides the legally permissible specialist services commissioned. Owners' declarations and official decisions remain separately required insofar as they are envisaged for the project.

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

A neighbouring area may require its own coordination

Investigation of the construction area may depend on availability of an adjacent area. This relationship is described using the specific task. Consent required and actual access are clarified before the appointment. Investigation on a more easily accessible substitute area does not automatically answer the original question.

Understand investigation reports and their limitations

Allocate organisational prerequisites and investigation results

Access, contacts and dates make execution plannable. The findings actually achieved arise only from the corresponding work and documentation. Retain these different pieces of information separately with clear allocation. Even during later project handovers, this keeps it clear which prerequisite is met and which specialist question is answered.

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
Person in an orange high-visibility vest with a MALÅ survey cart on a meadow.
Person in a high-visibility vest in front of a marked construction area with piles of soil.
Questions from planning

Questions about preparation in Troisdorf

When must permissions for neighbouring properties be clarified?

If neighbouring properties must be entered for the investigation required, Troisdorf also identifies permission to enter from their owners. Therefore use investigation planning to clarify the areas and access actually needed.

Does permission to enter also authorise the proposed groundworks?

Permission to enter initially concerns access to the area. Which groundworks are permissible and which technical prerequisites must be met for them require separate clarification. Utility plans and explosive ordnance documents also remain necessary insofar as required for the task.

What should be done about initially unavailable subareas?

Identify unavailable areas and have the implications for investigation assessed. Whether work in sections is appropriate depends on the project. Retain outstanding areas in planning and the report.

Which information helps at the first coordination stage?

Compile the site plan, type and depth of groundworks and existing explosive ordnance documents. Add information on access and available areas. For the official application, also observe the current document guidance in Troisdorf's service portal.

What should happen in the event of a suspicious find?

Stop work in the area concerned. Neither touch nor move the object, keep your distance and warn others. The City of Troisdorf identifies the Ordnungsamt or the police on 110 as reporting contacts. Follow their instructions.

Which change in site availability should be reported?

Every change affecting the access or work area required, with its precise location and period. This includes new closures, occupation or structural changes.

Does permission for the construction area automatically cover the access route?

The route actually required and permissions needed for it are clarified separately. A declaration for one area is not transferred indiscriminately to further properties.

What determines the survey workload and costs?

The city describes the enquiry, aerial photograph analyses, survey readings and explosive ordnance recovery as free of fees for applicants. It also identifies possible costs of further investigations and preparatory work. For federal or former federal properties, it describes assessment as generally chargeable. Private specialist services are agreed with their scope. Their costing considers area, depth, method, accessibility, preparatory services, interpretation and documentation.

Project enquiry

Documents for investigation in Troisdorf

Allocate access and permissions

Show work areas and access routes required, together with declarations already available or still outstanding. List the properties concerned with their respective reference to investigation planning. For each third-party area needed, identify the contact, status of the declaration required and identifiable conditions. Outstanding consents and access already available remain distinguishable. Also state which works are officially initiated and which specialist tasks you wish to commission separately. On this basis, the initial discussion coordinates the investigation scope required and outstanding prerequisites.

Describe current conditions

Identify time restrictions, known obstructions and changes since previous coordination. Supply available plans and official responses with their respective work status. Identify existing utility information and information still outstanding. For investigation in sections, time windows and areas concerned are stated together. After an interruption or change of company, the new site management receives the current results, location of outstanding areas and tasks still required. An area that has since become available is checked against the original investigation plans before further work there.

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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