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

Ordnance investigation in Hürth for a new property use

A surfaced area is to become a building with new connections, or an existing structure is to receive additional foundations. Such plans change the questions concerning the ground. FONTANA-EOD supports ordnance investigation for projects in Hürth by considering existing findings together with the groundworks actually planned.

Use

Distinguish former use from the future construction task.

Ground conditions

Identify known fill and existing assessments.

Execution

Clarify changed areas and depths before the work.

Discuss the project's technical requirementsExplosive ordnance assessment in North Rhine-Westphalia
Assess the construction project

Describe the new construction task through the actual groundworks

For a changed property use in Hürth, existing installations and new groundworks are considered together. We compare existing findings with the proposed areas, depths and construction methods. Information on fill and other specialist assessments remains identifiable with its own findings and limitations.

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.

Bring Hürth application details together on specialist grounds

The current Hürth forms distinguish aerial imagery analysis from ordnance investigation. The follow-up application identifies the explosive ordnance disposal service of the Düsseldorf District Government and the Hürth public order office and refers to the analysis file reference. For your project, details of the area, ground conditions and proposed work are coordinated with one another. Hürth is in the Rhein-Erft district, within the Cologne administrative district, in North Rhine-Westphalia. Identify the specific project location, for example Efferen, Hermülheim, Knapsack, Kalscheuren, Gleuel or Berrenrath, with the property and plots. The local procedure passes through the town of Hürth; the current applications involve the explosive ordnance disposal service of the Düsseldorf District Government.

North Rhine-Westphalia
Local context

The land-use designation is insufficient for the investigation

Connect Hürth applications with previous and future use

The current Hürth application for aerial imagery analysis asks about previous and future use. It also asks about specific ground interventions such as driving work or piled foundations. Preparation therefore needs more than the new land-use designation: describe which groundworks are proposed and which parts of the property remain unchanged. The aerial imagery analysis application requires a cadastral map at a scale of 1:5000 with the investigation area clearly marked. The property, plots and planned groundworks must correspond. For an alteration, new foundations or utility trenches are distinguished from installations retained on the plan. A later design option is passed on with its date and affected areas so that the analysis can be used for the project actually proposed.

The town chronology identifies expansion of the lignite industry from 1901 and a nitrogen factory from 1907 in Knapsack, together with severe war damage in 1944, particularly in Efferen and Knapsack. For a project, this information is linked with property records, former uses and area-specific historical findings. It does not describe a present-day contamination map and does not replace local assessment of the specific construction site.

Read ground assessments and ordnance documents according to their purpose

The application for ordnance investigation also addresses fill and an existing ground assessment. This information may help describe the ground and outstanding questions. A ground assessment is not, however, ordnance evidence merely for that reason. Its findings must be distinguished from ordnance documents according to investigation purpose and spatial reference. The operational application distinguishes fill deposited up to 1945 from fill deposited after 1945. Also identify the basis of any elevation or stratum information and state unknown values as such. A ground alteration is incorporated into the specialist and official procedure before it is carried out. The form also identifies current or former federal property, pollutant contamination and areas of suspected archaeological interest. Documents required for these matters are agreed according to the specific case.

Working together

Distinguish the tasks of client, designers and specialist contractor

Client and operator

The client describes the project and provides the existing project documents. The operator adds the requirements for use, access and timing. A coordinating contact agrees the assigned tasks with those responsible. Before commissioning, a clear record is made of which information is missing, who will obtain it and which decision the results are intended to inform.

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?

Derive the specialist question from use and groundworks

A new property designation does not describe an investigation method. The groundworks proposed and findings available are decisive. Technical conditions in existing installations are also considered. Only on this basis can it be assessed which investigation is suitable for the scope of findings required.

Assess historical documents

Agree preparation and the permissible commission

A private specialist service in North Rhine-Westphalia needs a specifically clarified legal and technical scope. Preparation required is agreed with those responsible. A note on a form does not constitute clearance for groundworks of your own. Before construction, official duties, the specialist commission and outstanding prerequisites remain distinguishable.

Compare investigation methods
Project types

Plan property changes clearly

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

Show retained and new structures separately

Identify which installations will remain and where additional groundworks are proposed. New foundations or connections may affect different areas from existing development. This distinction helps define the specialist task. It makes no additional ordnance findings about unchanged parts of the site.

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

Provide the basis of ground information

Older elevation plans, ground investigation reports and other information are provided with their source and revision status. Unknown stratum thicknesses remain an outstanding question. An assumption is not carried forward as a confirmed value. Specialist planning can then identify which information is reliable and what additions are needed for the specific task.

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

Compile different assessments clearly

Reports on ground conditions, contaminated land and ordnance are each retained with their attachments. Their investigation purpose and spatial reference remain identifiable. A common overview helps exchange between those involved. It does not replace specialist assessment of whether an individual finding is relevant to the groundworks now proposed.

Coordinate the sequence and tasks
Preparation

Prepare the scope and commission together

The investigation objective and suitable methods are determined from the planned groundworks and existing findings. Which activity may be commissioned privately under the specific North Rhine-Westphalia procedure is clarified separately before an agreement. For commissioning, the area to be investigated, findings required and preparatory services needed are identified. An enquiry for aerial imagery analysis, an official decision and a technical investigation carried out each serve their own task. The work needed next depends on the outstanding questions and local procedural status.

Establish what needs to be known before commissioning the work

For the Hürth project, previous use is linked with the groundworks actually planned. The new land-use designation alone does not define investigation scope. Describe new buildings, foundations and connections with their location, depth and construction method and assign existing ordnance documents. Information on fill and other assessments is included according to its respective purpose. This determines whether documents first need assessment, additional ground areas and volumes need investigation or findings already assessed require further work. The permissible commissioned specialist service and results documents required receive a specific scope.

Define the specialist task

Coordinate preparatory work with the investigation

Before investigation, the actual survey areas and access are clarified. A previously surfaced or commercially used area may contain installations and utilities relevant to preparation. Available information is compared with present-day conditions and coordinated with other trades. The preparatory work needed depends on the method and site. Additional breaking of the surface or other groundworks to provide survey access are professionally prepared in advance and are not undertaken independently. Ground changes remain identifiable with their actual status in the plans.

Clarify preparatory work in the programme

Agree a clear scope and schedule

The commission describes the groundworks actually proposed for the new use. Areas that are only partly accessible and outstanding prerequisites are considered in the scope. Effort and timing depend on access, documents and coordination; assessment and handover of results form part of the process. Unknown elevations or stratum information are identified as such. If planning or site conditions change, this is compared with the agreed commission before additional work. An unchanged property outline does not confirm that previous results cover every new foundation or connection activity.

Discuss the scope and schedule
Tasks at the site

Which changes matter for the construction task

01

New loads and foundations

Show where additional foundations, deeper excavations or retaining elements are proposed. If only the use above ground changes, state this too. The terms commercial, residential or storage do not reliably identify the actual groundworks. The Hürth application records previous and future use separately. Supplement these details with the actual groundworks: for a new extension, foundation footprint and depth are particularly relevant; for a change of use without additional groundworks, the unchanged ground relationship is relevant.

02

Known ground changes

Provide existing information on fill and earlier ground elevations. Distinguish documented information from assumptions. If the origin, age or thickness of a stratum is unknown, explicitly record this. Missing information must not be treated as confirmation of unchanged ground conditions. If stratum thickness is taken from a ground investigation report, include its investigation points and elevation reference. A value from another part of the property is not transferred to the new excavation without assessment. Those responsible clarify which supplementary information is needed for the proposed investigation.

03

Assessments with different tasks

Ground investigation, contaminated land and ordnance investigations answer different questions. Provide existing reports with their attachments without equating their results. For comparison, it matters where investigation took place, which question was addressed and which limitations each report contains. In particular, distinguish aerial imagery analysis from subsequent investigation. The follow-up application requires the analysis file reference, whereas an investigation report describes the areas and results actually investigated later. A recommendation remains recorded as a recommendation in the document overview until the associated work is substantiated.

04

Unchanged parts of the site

Not every area of a property being put to a new use is altered. Identify where existing installations are retained and where work will actually take place. This helps define the specialist task; it does not mean ordnance findings are already available for the remaining areas. Where several construction phases are involved, each proposed ground intervention has an identifiable reference to the site plan. A later utility centreline may affect a different part of the site from the foundation planned first. This additional task is compared with existing results before its work scope is defined.

Project documents

Documents that establish the next step

Connect results with the changed use

The report must identify which work and areas were actually investigated. Compare these details with current construction plans. New depths or added structures are assessed separately. Existing evidence is not transferred to the entire new design solely because the property address is unchanged. For handover, the areas actually investigated are compared with the most recent design used. Site management receives the associated plan attachments and limitations relevant to its work. If work is deepened or relocated later, the revision is passed to those responsible for specialist and organisational matters.

Keep differing elevations and areas unresolved until clarified

If documents use different elevation references or areas, this difference is clarified before they are used together. Documentation receives a traceable current revision. Findings still missing remain visible. Those involved later can then identify which results belong together and where additional specialist coordination is needed. For each part of the site, the common overview identifies the report, its date and associated attachments. After clearance work has been carried out, the associated clearance record with the area actually treated, clearance scope and results is also recorded in this overview. Investigated, uninvestigated and partly addressed areas remain separate. Findings still outstanding are linked with the unresolved task; they are considered together with the current plan revision in the next decision.

Construction sequence

Coordinate investigation and construction sections

Hand over the initial conditions and design together

Bring together existing ground information and the current plans. Known changes since older investigations are identified. A list of outstanding details helps the next coordination. The specialist task can then relate to the actual difference between existing conditions and proposed construction. Before commissioning, check which documents are already complete and which still need to be obtained. The service description assigns preparation, investigation, interpretation and handover to the respective proposed areas. Access, contacts and contributions from other specialist authorities or parties are identified with their actual status.

Coordinate the construction phase with us

Assess changes before the next construction phase

New foundation locations, changed depths or additional utilities are compared with previous results. Pass these changes to the specialists involved. The supplementary scope required is specifically determined. Site management then receives the appropriate evidence for the forthcoming work. When the contractor changes, the relevant design, valid reports and outstanding tasks are handed over together. Confirm within the project process who receives the new details and before which groundworks the supplementary comparison is needed. A collection of files alone is linked to the specific construction phase for this purpose.

Coordinate the construction phase with us
Method selection

Select methods according to the task and survey conditions

Historical records and aerial photographs

Historical aerial imagery analysis and other older documents help to place the basis for suspected ordnance in its spatial context. Availability, information value and area boundaries of the imagery determine the state of historical knowledge. The absence of a visible finding is not a present-day subsurface measurement. Documented changes in use and ground conditions are linked with other findings and planned groundworks. Information on earlier fill is assessed with its source and time reference. Historical assessment supports investigation planning but does not confirm all work for a future change of property use as a blanket statement.

Understand aerial photograph assessment

Magnetometric survey

Magnetometric methods detect magnetic anomalies. Suitability is assessed according to expected objects, ground conditions and the investigation area and volume required. Utilities, fences and existing structures can influence interpretation. Actual conditions are therefore described for the newly affected areas. Signal strength alone does not identify an object as ordnance. Measurement, assessment and further investigation are planned together. A result concerning an earlier use is checked with its actual ground area and volume before assignment to the new construction task.

Understand the scope of magnetometry

Electromagnetic methods

Electromagnetic investigations may be suitable for certain metallic target objects and site conditions. Selection considers the information required, accessible survey areas and interfering installations; equipment availability alone is insufficient. Ground composition and fill information is included according to its documented status. Results receive spatial references and the actual investigation conditions. Any addition required follows from specialist assessment. The new land-use designation alone determines neither a device nor an investigation scope already achieved.

Understand electromagnetic surveying

Ground-penetrating radar

Under suitable conditions, ground-penetrating radar can provide information on subsurface structures and reflections. Ground conditions, moisture and installations affect interpretability. A reflection is not automatically ordnance; an unremarkable area does not confirm conditions at any arbitrary depth. Specialist interpretation and limitations are documented with the commission. Before an existing report investigating ground composition is used as ordnance evidence, its purpose and scope are checked. Information from a ground assessment and an actual ordnance investigation remain distinguishable.

GPR and limitations

Deep-ground and downhole surveys

For deeper groundworks, it may be necessary to check whether investigation from the surface can provide the information required or whether another approach is needed. New foundation positions and particular construction methods are described with location, depth, elevation reference, borehole layout and known utilities. The provision of suitable investigation access is professionally prepared. A standard grid or general depth figure does not replace this task. Results remain tied to the ground areas and volumes actually investigated and the method used. Different ground levels are clearly assigned when depth information is compared.

Prepare deep interventions

Survey during construction

If a necessary advance investigation cannot be completed in full, it is assessed whether a professionally planned approach during construction is suitable. Investigation, interpretation and communication of findings are linked with the actual work for the new use. Visual observation of excavated material alone does not replace a necessary ordnance survey. Site management receives an allocation of specialist work, new findings and unresolved areas within the sequence. Additional groundworks or proposed ground alterations are professionally agreed before the affected activity.

Agree the approach during construction
Technical assessment

Plan investigation and new groundworks together

Assess existing indications

A historical aerial photograph analysis is brought together with other findings for the identified area. The new use alone establishes neither suspected ordnance nor its exclusion. The information available and specific work to which specialist assessment is to relate are decisive.

Assess investigation conditions

The information to be considered in a survey includes fill, utilities and installations. Their significance depends on the method and question addressed. Without specialist assessment, stratum information does not establish any blanket achievable investigation depth or measurability.

Agree the work required

A clearance plan can relate investigation, preparation and construction to one another. Any necessary preparatory groundworks must also be agreed. Details in an application form are not instructions to strip an unresolved area independently or expose utilities there yourself.

Next steps

Keep property details current through to construction

01

Describe the initial conditions

Bring together existing plans, reports and reliable information on former use. Note when documents were produced and whether the area has changed since. For unsubstantiated assumptions, record a clarification point rather than entering a supposed fact in the application. For initial contact, state the project address, proposed work and current plan revision. Specialist planning checks existing ordnance reports for their area and depth references, limitations and identifiable gaps. It assigns official notes and investigations already carried out to their respective functions. The document overview identifies which results can be used for the new construction task and which question still needs an answer.

02

Supplement historical findings where needed

Existing aerial imagery analyses and historical indications are related to the present-day project area. Where the basis is incomplete, the necessary supplementary research or aerial imagery analysis is carried out through the appropriate specialist or official route with its question defined. The findings obtained are assessed together with previous use and current plans to determine investigation needs. An entry in the town's history is first checked for its actual relevance to the property.

03

Show the application area clearly

The Hürth follow-up application provides for a specific site plan of the areas to be investigated. Assign the construction task to the plan. Where there are several parts of the site, differences in depth or construction method should remain identifiable so that questions are not handled solely under a general property address. Investigation planning defines suitable methods according to the findings required, depth of groundworks and actual site conditions. Existing utilities, installations and interference are taken into account. The commission describes its spatial scope and prerequisites for carrying it out. The marked area remains linked to the specific construction task if a foundation or utility route changes.

04

Clarify access and associated conditions

The follow-up application also records utilities, possible pollutant contamination and areas of suspected archaeological interest. Communicate existing findings about these matters and identify outstanding points. Coordination and protective measures required are clarified with those responsible before the work. On the basis clarified, specialist personnel carry out the investigation or agreed supervision permitted within the respective legal and technical scope. Data are recorded with their location, local measurement conditions and limitations. If conditions change, the further approach is coordinated. A suspicious find triggers the prescribed reporting and hazard prevention procedures.

05

Assess and clearly document findings

The data and findings collected are professionally assessed in the context of the investigation objective, method and site conditions. Interference and areas that cannot be investigated remain identifiable. The report documents the work carried out, results, location and depth references, and limitations; maps and attachments remain connected to it. Any further clarification required is assigned to the affected area. A measurement anomaly is professionally assessed and is not identified as a particular object solely on the basis of the measurement signal.

06

Update changed plans

If a deeper excavation or an additional connection is added during planning, identify the change from the assessed version. Only a specialist comparison can establish whether the existing results are sufficient. A new description of the intended use must not obscure a change in the actual ground intervention. For the next construction phase, hand over the assessed report together with its associated plans. Site management compares the forthcoming work with the investigated area and the documented limitations. Outstanding tasks are assigned a responsible contact and linked to the next ground intervention. The plan and report versions used remain traceable for later additions.

Documentation

Assign results to the specialist task and area

Findings and their scope

The handover includes the relevant ordnance reports, identifying the investigated areas, results and limitations. Supplementary geotechnical or contaminated-land documents remain identifiable as separate specialist reports. If findings refer to different areas or elevations, this difference must be clarified before the documents are used for a shared construction section.

Project responsibilities

FONTANA-EOD performs the agreed specialist service and documents its scope. Statutory responsibilities remain with the competent authorities. The BFR Kampfmittelräumung provide technical principles for planning and documentation. They apply directly to federal properties; elsewhere, local requirements and the specific project task are decisive.

Working approach

How FONTANA-EOD works

Document the agreed specialist service clearly

FONTANA-EOD undertakes the agreed specialist task using the available findings and the current plans for ground interventions in Hürth. Information on previous use, ground structure and other assessments is considered according to its purpose. Accessible areas and the results needed are agreed before the work starts. If plans or local conditions change, the scope is reviewed before the affected work proceeds. The report documents the work actually undertaken and its limits. Site management can relate the findings to the new construction work and identify matters still requiring clarification.

Discuss the investigation task

The task before the equipment

Method selection starts with the information missing for the future groundworks. Specialist planning considers the available knowledge, actual conditions and the volume of ground affected. An available instrument or a neighbouring property converted to a similar use is not sufficient as the sole basis for selection. Information on fill and existing assessments is considered within its stated scope. The method is justified for the specific investigation task, rather than inferred from the description of the new use.

Keep limitations visible

Inaccessible areas and areas where interpretation is restricted are identified with their actual boundaries. Site management can relate new foundations, connections or other affected activities and any necessary additions to these areas. A general statement of the property area does not replace this distinction. Planning and construction teams agree when a suitable investigation can be carried out. Previously investigated volumes of ground and those additionally affected remain identifiable, even where the surface was paved or built on for a long time.

Clarify changes before intervening in the ground

If location, depth or construction method changes, the new version is compared with the existing results before the affected work begins. This also applies where altered ground levels affect the reference for depth information. Specialist planners receive a clear account of the difference from the previous version. Their response and any necessary additions are assigned to the affected volume of ground. An unchanged project name or property outline does not replace this comparison.

Hand over the report and plan together

At handover, reports and their associated plans are provided with the relevant area, elevation and planning version. A short overview can point to findings, limits and outstanding tasks for the new use. It does not replace the documented investigation scope. When site management or contractors change, the origin and limitations of other assessments also remain clear. Subsequent construction work can use the relevant results and identify the information still needed for additional groundworks.

Understand the results

Use technical statements for the next decision

Read an assessment according to its purpose

A geotechnical report can contain important information about strata. Whether it also answers a particular question depends on its investigation brief and content. Record these limits when passing it on. A shared project name does not make different specialist reports interchangeable forms of evidence.

Understand investigation reports and their limitations

The new use does not describe every ground intervention

Even where the intended future use is similar, foundations, connections or intervention depths may differ. Conversely, a change in the description of the use does not automatically mean that new groundworks are planned. Describe the actual construction work. This information enables a specialist comparison with existing findings and outstanding requirements.

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 changes of use and ground conditions in Hürth

Does a different use automatically require a new investigation?

The description of the use alone does not establish this. First describe the planned groundworks and compare them with existing findings. These, together with the applicable requirements, determine what further clarification is needed. Agree the required process with the responsible parties before the affected groundworks begin.

What should I do if information on fill is missing?

Identify the missing information clearly and provide existing assessments or older elevation plans. Do not treat estimates of unknown information as established values. The additional information required must be agreed by specialists for the specific investigation.

Can I submit the ground investigation report as an ordnance report?

It may contain supplementary information about the ground, but it does not replace an ordnance report. What it establishes depends on the particular investigation task. Include existing assessments and their annexes, and have their relevance assessed by specialists.

How does the follow-up application relate to the aerial photograph analysis?

The Hürth form asks for the file reference of the aerial photograph analysis. Keep the associated notification and map together with the current plan. This allows the proposed investigation and existing indications to be assigned to the same area.

What must happen if suspected ordnance is found?

Stop the affected work and move away. Leave the object untouched and keep other people away. Call the police immediately on 110 from a safe distance and follow the authorities' instructions.

How are installations that will be retained shown on the plan?

They remain distinguishable from the newly planned ground interventions. This allows the specialist task to be defined without extending findings to areas that were not considered.

What matters when elevation information differs?

The reference used in each case must be traceable. Differences between reports and plans are clarified before the information is used for the same ground intervention.

What information and cost factors matter for an additional foundation?

Its location, depth and construction method compared with the previous design. These determine whether existing results are sufficient or an addition is needed. The effort also depends on the size and accessibility of the area, the planned intervention depth, suitable methods, interference and usable previous findings. Necessary preparatory work, interpretation and documentation are agreed with their scope for the specific task. Costs for statutory hazard response are distinguished from privately commissioned services.

Project enquiry

Coordinate the new use and groundworks in Hürth

Show existing structures and changes

Mark the installations to be retained and the newly planned ground interventions on the current plan. For your project in Hürth, the current site plan, planned groundworks and existing assessments are useful. State what changes are planned from the previous use and what information about the site is missing. This provides a concrete basis for discussing the specialist task.

Include complete assessments

List their origin, investigation purpose and identifiable gaps separately. Also state which earthworks are due to start first and which areas are not yet accessible. This allows necessary preparatory work and the handover of results to be coordinated in good time.

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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