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

Explosive ordnance surveys in Iserlohn before ground intervention

For an extension, utility trench or new foundation, an ordnance assessment needs more than the property address. Where will work take place, how deep will it go and which plans will it follow? FONTANA-EOD helps developers and designers with projects in Iserlohn compile this information for specialist clarification and correctly assign existing results.

Planned works

Describe the groundworks actually planned.

Site plan

Mark work areas clearly on the plan.

Result

Derive further needs from the findings.

Assess the construction project

Link the enquiry to the groundworks actually planned

For an ordnance assessment in Iserlohn, describe the construction task, location and intervention depths clearly. We assess existing findings and define further specialist needs. Official aerial photograph analysis and any subsequent investigations are distinguished by what each can establish.

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.

Use the responsible Iserlohn authority and enquiry route

Iserlohn is in the Märkischer Kreis district, within the Arnsberg administrative district in North Rhine-Westphalia. The town of Iserlohn handles aerial photograph enquiries through its public order and trade affairs department. Its current service page lists details of the planned construction work and a site plan as components of the enquiry. Further needs depend on the findings and the specific ground intervention. For statutory ordnance tasks, the explosive ordnance disposal service at the Arnsberg District Government supports the local public order authority.

The town lists kampfmittelueberpruefung@iserlohn.de as the email address for aerial photograph enquiries. Details of the planned construction work and the site plan refer to the same revision. Identify the structures planned and the groundworks they require. For properties in the surrounding area, determine the responsible local authority from the actual municipality. A project crossing several municipalities needs a traceable allocation of sections. Each response remains linked to its location and plan version. Record what finding is needed before the first planned work for subsequent processing. Further project locations are listed in the regional overview.

Local context

Relate historical information to today's ground interventions

Observe Iserlohn's guidance on aerial photograph enquiries

On its “Munitionsfunde” service page, the town of Iserlohn specifies an application for aerial photograph analysis for planned ground interventions deeper than 80 centimetres. The enquiry includes information about the construction work and a site plan. According to the town, further investigations may be required if the analysis indicates possible ordnance.

The town of Iserlohn describes the air-raid shelter tunnel beneath the Oberste Stadtkirche as a Second World War construction project. According to the town, construction began in the Bilstein in summer 1943. The town relates the shelter planning at the time to the local metal industry as a potential target. For present-day projects, such historical indications are related to the area actually affected using suitable images and records. Later changes to ground levels or use are traced using existing documents. Today's project address and precise ground intervention plan determine which historical question requires clarification for further investigation.

Assess the depth figure and existing evidence separately

The depth mentioned describes this local procedural guidance. It is not an assurance that shallower ground interventions are generally safe. Nor does submitting an application replace an investigation result. Before work begins, existing findings, official requirements and the specific ground intervention must be considered together.

To investigate an area of suspected ordnance in Iserlohn, information from the periods available is brought together. Earlier buildings, documented wartime impacts, reconstruction or later development may involve different documents. Research therefore identifies the origin, spatial relevance and limits of the findings. An older map is compared with current property and ground intervention plans. Unclear assignments are addressed before decisions on further measures. Historical analysis and technical investigation retain their different tasks. Existing official requirements are assigned to the respective area and the next ground intervention.

Working together

Distinguish the tasks of client, designers and specialist contractor

Client and operator

The client describes the project and provides the available project records. The operator adds requirements for use, access and timing. A coordinating contact brings the parties together; individual tasks remain assigned to the named parties. Before commissioning, it is clearly recorded what information is missing, who will obtain it and what decision the result is intended to prepare.

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 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.

The local public order and trade affairs department receives the enquiry under the municipal procedure. The state explosive ordnance disposal service at the Arnsberg District Government supports the local public order authority within the respective remit. For a private commission, the permissible specialist task and necessary authorisations are clarified. If a suspicious object is found, the responsible authorities lead further hazard response. Project participants record which documents and responses are needed for the work section concerned. A need for ordnance recovery is coordinated with the permissible task and the competent authorities.

Investigation task

Which specialist task comes next?

Understand aerial photograph analysis in terms of its purpose

A historical analysis provides findings on possible ordnance contamination and the need for further state action. Its result is read alongside the specific plans. It may raise further investigation questions. A particular subsequent method is not established merely by submitting an application, but is determined from the findings and project conditions.

Assess historical documents

Link supplementary specialist work to the North Rhine-Westphalia procedure

A private commission has a clear question and boundary with statutory tasks. Legal requirements and necessary authorisations are checked beforehand. Existing requirements remain part of planning. The technical service description links the task at the specific site with statutory conditions and interfaces with the authorities.

Compare investigation methods
Project types

Compile a clear description of the construction project

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

State the purpose of the construction work precisely

Describe which structures or installations are to be built, altered or removed. A general description such as conversion often leaves the scope of groundworks unclear. Planned ground interventions are therefore assigned individually. This enables the responsible authority to identify the specific work addressed by the enquiry and accompanying plans.

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

Relate the site plan to intervention depths

Each affected area is shown clearly on the plan and linked to the depth information available. The elevation reference used remains identifiable. Values not yet established are marked provisional. This prevents a single figure being mistakenly applied to every connection, foundation or other project activity.

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

Show additional components of the work

External connections, access routes involving groundworks or other supplementary ground interventions may extend beyond the building footprint. Include them in the description where they form part of the project. Earlier results are checked for these areas too. A finding for the main area is not treated as evidence for all ancillary work without a traceable comparison.

Provide specialist supervision of excavation
Preparation

Prepare the scope and commission together

The specialist service is determined by the planned ground intervention and the conclusion required for it. 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

For the Iserlohn commission, describe the actual groundworks: extension, foundation, utility trench and any associated additional work areas. These details are linked to the site plan and existing ordnance documents. This establishes whether documents first need assessment, specific volumes of ground need investigation or already assessed findings need further work. The permissible commissioned specialist service and results required are defined by this scope. A building footprint alone does not show every planned ground intervention. Outstanding location or depth options remain identifiable for further specialist clarification.

Define the specialist task

Coordinate preparatory work with the investigation

Before the work begins, clarify actual survey access, utility information and interfaces with other trades. Also identify work areas alongside the main trench where groundworks are planned. Necessary preparatory work depends on the method and site. Additional breaking out or other interventions to create investigation access are prepared with specialist input and the responsible parties, rather than undertaken independently. The enquiry, commissioned scope and actual site conditions are compared before the affected work starts.

Clarify preparatory work in the programme

Agree a clear scope and schedule

The commission identifies the first planned groundworks and the finding needed for them. Assessment and handover of results form part of the process. Effort and scheduling depend on actual access, documents and coordination. Official aerial photograph analysis, possible technical investigations and later results remain distinguishable by their respective status. If location or depth changes, specialists assess whether the agreed commission still fits. A successfully sent enquiry is not entered into the construction programme as an investigation already performed.

Discuss the scope and schedule
Tasks at the site

Prepare the enquiry so the ground intervention is clear

01

Identify the construction task

Describe what will actually be built, altered or removed. The term conversion alone leaves open whether work is solely above ground or affects foundations, shafts or utilities. Also identify preparatory work if it already involves ground intervention. This defines the specialist question before the first intervention.

02

Show areas, rather than addresses alone

Mark the proposed work areas on a legible site plan. Property boundaries, existing buildings and planned structures should be distinguishable. Any connection outside the main construction area must also be shown. An application for one part of a site cannot automatically be transferred to the entire property.

03

Provide traceable depth information

Assign the planned intervention depth to each structure. Where ground levels have changed, state which condition the depth refers to. A general figure for the eventual building height does not answer this question. If the foundation design is not yet settled, identify the outstanding planning status rather than assuming a scope already established.

04

Include earlier documents in full

If an earlier analysis or technical reports are available, their maps and limitations are also needed. A single sentence giving a result may lose its spatial context. Clarify which documents concern the current project and which relate to other work. This helps establish which findings can continue to be used.

Project documents

Documents that establish the next step

Distinguish the enquiry, analysis and investigation

An acknowledgement of an enquiry documents a procedural step. An analysis or investigation, by contrast, contains specialist findings within a specific scope. These documents are kept separately with their respective status. This makes clear for subsequent construction planning which results are actually available and which steps remain outstanding.

The project file contains the submitted description, associated site plan and responses relating to them. Result reports are provided together with all maps and annexes. Each document is assigned its investigation purpose and affected area. A missing annex or illegible drawing is specifically clarified. A clearance record is assigned to the clearance operation actually performed. Findings that can be used and questions still outstanding remain distinguishable for further planning.

Compare the current construction work with the result

Before the planned work, compare the plans with the findings available. Changed areas or depths are assessed separately. Site management receives complete documents with the associated maps and limits. Older correspondence is not used to close the current ordnance question merely because it concerns the same address.

At handover, the plan version, result report and planned subsequent work are considered together. An additional foundation, extended utility section or new lateral working area is compared with the documented boundary. Site management receives the documents for its specific construction work. If further findings are needed, identify the specialist task and responsible contact. Outstanding conditions and areas already addressed remain traceable even when contractors change. New results are assigned to the relevant construction phase.

Construction sequence

Coordinate investigation and construction sections

Bring plan information together before the enquiry

Provide a clear description, site plan and existing result documents. Identify outstanding depths or alternative construction options. The enquiry can then refer to the scope actually planned. A later addition is easier to trace if the submitted plan already has a clear revision and complete area labels.

Incorporate responses into further planning

Official and specialist responses are assigned to the relevant plan version. Further information needed and additional investigations remain identifiable as outstanding steps. If construction changes, a new comparison is made. Handover to site management includes the current state of knowledge, rather than only the original application letter.

Method selection

Select methods according to the task and survey conditions

Historical records and aerial photographs

Historical aerial photograph analysis and other older documents help locate the basis for suspected ordnance. Images, interpretability and area boundaries are linked to the groundworks actually planned. The absence of a visible indication is not a technical investigation of today's ground. Other available findings are considered. For the enquiry, the extension, trench and additional working areas are assigned clearly on the plan. Any later relocation of the ground intervention is compared with the spatial basis of the analysis.

Understand aerial photograph assessment

Magnetometric survey

Magnetic methods detect magnetic anomalies. Suitability is assessed according to the expected objects, ground conditions, interference and volume requiring investigation. Utilities, fences and existing structures can affect interpretation. Signal strength alone does not identify explosive ordnance. Measurement, assessment and further clarification are linked to the specific specialist task. Coverage is assigned to the planned trench or foundation. A result alongside the ground intervention does not, by itself, establish the finding for its own volume of ground.

Understand the scope of magnetometry

Electromagnetic methods

Electromagnetic investigations may suit certain metallic targets and site conditions. Selection considers the finding required, accessible survey areas and interfering installations, rather than instrument availability alone. Results are documented with their locations and actual investigation conditions. Any necessary addition follows from specialist assessment. Local procedural guidance for enquiries does not, by itself, determine either the instrument to use or sufficient investigation scope. Method selection relates to the groundworks actually planned.

Understand electromagnetic surveying

Ground-penetrating radar

Under suitable conditions, ground-penetrating radar can provide information about subsurface structures and reflections. Ground conditions, moisture and installations affect interpretability. A reflection is not automatically ordnance; an area without notable signals does not confirm any arbitrary depth. Specialist interpretation and limits are documented with the commission. An earlier radar survey is read according to its investigation purpose and coverage. The location of today's trench and its additional working areas is compared with what the findings can actually establish.

GPR and limitations

Deep-ground and downhole surveys

For deeper ground interventions, it may be necessary to assess whether a surface investigation can establish what is needed or whether another approach is required. Positions, depths, reference elevations, borehole layout and known utilities are prepared for this purpose. Suitable investigation access is also planned by specialists. A standard grid or general depth figure does not replace this task. The technical task is defined for the volume of ground required. Municipal procedural guidance is not used as a blanket statement about its ordnance status.

Prepare deep interventions

Survey during construction

If a necessary advance investigation cannot be completed in full, specialists assess whether a planned approach accompanying construction is suitable. Investigation, interpretation and communication of findings are related to the groundworks actually planned. Visual observation of excavated material alone does not replace a necessary survey. Site management receives the allocation of specialist work and unresolved areas within the programme. Lateral working areas or an additional deepening of the trench are compared with the agreed approach before construction. The scope actually addressed remains traceable in the result.

Agree the approach during construction
Technical assessment

Analysis, measurement and assessment serve different purposes

Check historical indications

The historical aerial photograph analysis examines existing image sources and may provide indications for further ordnance assessment. What it establishes depends on the documents that can be interpreted. It must not be equated with a technical investigation covering the entire area. A result is incorporated into planning within its actual evidential scope.

A site plan links the property, existing buildings and new structures through traceable reference points. The space actually needed for the excavation, support works, connections and preparatory groundworks is distinguished. If several drawings exist, identify the date and validity of each version. A plan legend explains which area was investigated and which is only planned for construction. Existing utilities and other known installations are considered at their locations. Metallic interfering objects can affect interpretability; the survey limits actually reached are described in the result report.

For a specialist task requested as borehole clearance, the point location, depth reference and findings needed are defined before commissioning. The elevation reference also remains identifiable for other ground interventions. A depth from existing ground level and a depth following prior soil removal may concern different volumes of ground. During preparation, show these conditions together with the structures affected. An added utility or a shaft deepened later is identified on the current plan. Further investigation needs depend on this change and the findings actually available.

Coordinating technical investigation

Whether a survey is needed, and which method is suitable, depend on the task and local conditions. Existing buildings, utilities or other interference may affect the investigation. Specialist preparation therefore also clarifies accessibility and interpretability. A construction project's description does not establish a universally suitable survey method.

Justify the next steps

Where a clearance plan is required, it brings together the findings and measures derived from them for the specific project. Not every application automatically triggers the same sequence. What matters is which questions remain unresolved after the work undertaken so far and what finding is needed before the next planned ground intervention.

Next steps

From application to an assessed work area

01

Use a current plan version

Match the drawing used for the enquiry to the actual construction plans. Superseded designs cause avoidable questions if structure locations or depths have since changed. Record the plan version and responsible contact so questions about the same project can be answered. At first contact, identify the construction task and decision needed. Existing ordnance reports are checked with their complete maps and annexes.

02

Assess the official response

Read conditions and guidance on further steps alongside the result. Clarify outstanding points with the responsible authority and commissioned specialist planners. An acknowledgement or notice that documents have been forwarded does not establish whether the planned work can begin. Where needed, unresolved historical information is researched and assessed using suitable records and images. The required official aerial photograph analysis is initiated through the local authority. Methods and investigation scope are selected according to target objects, ground conditions, intervention depth, interference and access. Conditions for undertaking the work are agreed with the specialist planners and responsible authorities involved.

03

Report changes before ground intervention

If a shallow connection trench becomes a deeper excavation, compare the previous investigation scope with the changed project again. This also applies to a relocation within the same property. Additional measures are derived from this comparison and agreed before the changed groundworks. Once the prerequisites are clarified, the agreed investigation or suitable specialist supervision is undertaken. Data and observations are interpreted and assessed for their significance to the construction task described. Usable results, anomalous findings and outstanding questions remain distinguishable.

04

Hand over results to site management

Those undertaking the work need the documents for their actual work area. These include the areas and depths covered as well as remaining limitations. Decide who communicates construction plan changes so that a new drawing is not confused with a result for a superseded design. Reports and maps document the scope actually addressed and the results. The decision on subsequent work identifies additions or coordination needed before the next step. For tendering, describe the specific specialist task and expected result documents.

Documentation

What traceable evidence must contain

Findings and their scope

Keep the analysis, technical reports and associated plans together. The area investigated, depth considered, method used and limits of the result must remain identifiable. For a later extension, this makes it possible to check whether existing documents are sufficient or further specialist clarification is needed.

Project responsibilities

FONTANA-EOD undertakes the agreed specialist commission; the relevant competent authorities make official decisions. In North Rhine-Westphalia, local public order authorities and state explosive ordnance disposal services must be involved according to their respective tasks. The BFR Kampfmittelräumung apply directly to federal properties. Their technical principles for planning and documentation can also provide guidance for other projects.

Working approach

How FONTANA-EOD works

Document the agreed specialist service clearly

FONTANA-EOD undertakes the agreed specialist task for the identified groundworks in Iserlohn. Before the work begins, existing findings and required results are related to the same plan version. Accessible areas and prerequisites are agreed. Changes to plans or local conditions are reviewed before the affected work proceeds. The report documents the work actually undertaken and its limits. Site management can identify what finding is available for the next trenching or foundation step and which additional task remains outstanding.

Discuss the investigation task

The task before the equipment

Method selection starts with the information missing for the ground intervention described. Specialist planning considers existing results, ground conditions and actual circumstances. An available instrument or similar neighbouring work is not sufficient as the sole basis. The selection is justified for the location and volume of ground required. Information from the aerial photograph enquiry is linked with current construction plans so new detailed designs do not change the previous task description unnoticed.

Keep limitations visible

Inaccessible areas and areas with restricted interpretability are identified with their actual boundaries. Site management can assign the groundworks affected and necessary additions to them. A general total area figure does not replace this distinction. Planning and construction teams agree when a suitable investigation can take place. If an additional work area is needed alongside the utility trench already considered, its state of knowledge is clarified separately. The adjacent investigated area does not replace this finding.

Clarify changes before intervening in the ground

New locations, additional depths or different construction methods are compared with existing results before the affected work begins. Specialist planners receive a clear account of the change from the previous enquiry and investigation. Their response and necessary additions are assigned to the affected volume of ground. This also applies to an additional shaft or changed foundation position within the same project. The project name and property address remain important for identification but do not, by themselves, confirm an unchanged investigation scope.

Hand over the report and plan together

At handover, reports and associated plans are provided with the trench, shaft or foundation areas actually addressed. An overview can list findings and outstanding tasks important for the next step. It does not replace the documented investigation scope. When designers, site management or contractors change, the groundworks underlying the enquiry and results remain traceable. New construction details are compared with these before the associated ground interventions begin.

Understand the results

Use technical statements for the next decision

A depth figure describes the ground intervention

The application threshold stated by the town is not a statement that a layer of ground is safe. Known indications and requirements must also be considered for other ground interventions. Describe the actual work with its elevation reference. Merely staying below a numerical value does not replace project-specific assessment of existing findings.

Understand investigation reports and their limitations

A response needs a clear plan version

If several versions of a plan exist, it must be clear which version a finding refers to. Changes to location or depth are identified separately. Further questions can then be coordinated specifically. A part of the earlier result that remains applicable is retained without extending it to the entire new plan.

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 ordnance enquiries in Iserlohn

What does the town say an aerial photograph analysis enquiry should include?

Iserlohn specifies details of the planned construction work and a site plan. Add the groundworks actually intended so areas and intervention depths can be compared by specialists. The town's current guidance governs submission. Coordinate the need in good time before the planned ground interventions. The local public order authority involves the state service within its remit.

Does the 80-centimetre figure mean a safe depth?

No. The town's procedural guidance is not a general assurance that shallower work is safe. Existing indications, specific groundworks and official requirements must still be considered. The depth figure alone does not establish freedom from ordnance.

Is a survey always needed after aerial photograph analysis?

This cannot be decided in general terms. Further needs follow from the documents that can be interpreted, the indications identified and the planned work. A technical investigation must be suited to the finding needed and site conditions. Ground conditions, depth and interference limit what the method used can establish.

Can an older report be used for a new extension?

First check whether it actually covers the new construction area and planned depth. Provide the complete report with its maps and limitations. The same address or an earlier start of construction on the property is not sufficient evidence.

What should you do if a suspicious object is found?

Stop the affected work, do not touch or move the object, and move away. Keep other people away. Notify the police immediately on 110 from a safe distance and follow the authorities' instructions.

Is an acknowledgement already a specialist response?

No. It confirms receipt of the enquiry. Specialist findings and any further steps follow from the respective analyses and notifications. Specialist work proceeds from document review and necessary historical analysis through method selection and investigation to assessment and documentation. Results are compared with the plans before subsequent work.

Which factors determine effort and costs?

The method, investigation scope, depth, interference and access determine the effort required. Missing documents or necessary preparation are considered during coordination. For commissioning, agree the specialist service and required result documents with their specific scope. Cost allocation is clarified with the responsible parties under the respective procedure.

Does a response to the first site plan apply to every later change?

This must be checked. New areas, depths or construction methods are compared with the scope of the existing finding and coordinated again where necessary. Planned depth together with a traceable reference to each area helps with assessment. Outstanding values are identified and later compared with the settled design.

Project enquiry

Prepare the first technical discussion

Describe the construction task clearly

Identify the individual activities and their locations on the current plan. Add the project address, cadastral plot, official correspondence, utility plans and complete ordnance reports with their maps. The sector overview explains typical interventions and the documents they require.

Assign plan versions and depths

Identify reference elevations, provisional values and changes to construction. State outstanding foundation or utility details, the earliest ground intervention, areas not yet accessible and the people responsible for answering questions.

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.