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

Explosive ordnance surveys in Ahlen before investigation and construction works

Ground investigation works may be needed before an excavation can be designed. These preparatory activities also disturb the subsurface. For projects in Ahlen, FONTANA-EOD helps clients and design offices clarify the explosive ordnance investigation requirements for the preliminary investigation and distinguish them from the later construction works.

Ground investigation points

Specify planned points and depths clearly.

Access routes

Include the groundworks required for access.

Construction area

Check later interventions separately against the results.

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

Plan preliminary investigation and construction with their respective scopes

For your project in Ahlen, we distinguish point investigations, associated groundworks and the subsequent construction works. Existing information is compared with the areas and depths intended for each. This allows the further investigation requirements to be defined for the next work step actually planned.

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.

Local coordination for the specific construction task

Ahlen is part of the district of Warendorf in the Münster administrative district in North Rhine-Westphalia. Official Gazette 36/2025 of 10 October 2025 contains notices on development plan No. 49, “Hohle Eiche”. The municipal service portal lists Group 1.2 – Law, Public Order and Central Procurement. The specific explosive ordnance investigation procedure for your project is coordinated with the local public order authority. Available documents are assigned to the actual property and planned groundworks.

Identify the project address, parcel and location of each investigation point. For access routes, setup areas or additional utility works, state whether and where soil will be disturbed. For projects in the surrounding area, the local contact body depends on the actual municipality of the project location. A continuous route design may therefore involve several authority procedures. Assign responses and investigation results to the respective section. The technical preparation records which conclusion is needed before the first intervention and which documents follow for the later construction phase. Other project locations are shown in the regional overview.

North Rhine-Westphalia
Local context

Compare historical information with present-day investigation tasks

Understand the announced preparatory works for Corridor B

In the City of Ahlen's Official Gazette of 24 January 2025, Amprion announced preparatory works for the Corridor B route planning. For the period then specified, March to May 2025, these included ground investigations and explosive ordnance investigations on suspected areas. Technical preparation identifies the working areas and required access routes separately, with the respective groundworks for each.

The town chronicle of Ahlen records air raids during the Second World War and identifies 23 March 1944 as the date of the largest attack on the town. For a present-day suspected explosive ordnance area in Ahlen, historical photographs and other suitable documents are related to the areas actually affected. Reconstruction, demolition or development may separate the former condition from today's use. These changes are traced using the available files and plans. A geotechnical investigation answers different questions from the historical assessment of suspected explosive ordnance. The two tasks therefore retain their own information bases and results.

Assess investigation points and the future construction area separately

The announcement at that time is not a report of completed works and provides no evidence for another property. For your own project, the question remains: which investigation is initially needed for the preliminary ground investigation, and which questions can only be answered with the later construction plans? A result for individual investigation points does not automatically cover the future excavation or route area.

The current investigation plans, existing aerial photograph assessments and technical results reports are brought together for comparison. Earlier area descriptions are assigned to today's address and the points actually planned. A map may represent a different time or area from the subsequent design. The reference points used and the respective purpose of investigation therefore remain identifiable. Outstanding historical questions are researched before deciding on further measures. The local body is involved in the official procedure. The later construction design adopts the results within their documented scope and describes additional interventions separately.

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.

For projects within the town, the local public order authority and the state explosive ordnance disposal service at the Arnsberg District Government are involved through the prescribed authority procedure. The state body performs its tasks within the respective procedure. A private appointment requires a permissible specialist task and the necessary permissions. In the event of a find, the competent bodies determine further hazard prevention measures. The project participants record the responses required for each work section. Any requirement for ordnance recovery is coordinated with the permissible task and the competent authorities.

Investigation task

Which specialist task comes next?

Describe the investigation task before selecting a method

First, it is recorded which question needs to be answered for which intervention. Historical information, location and technical conditions inform this assessment. A geotechnical investigation and an explosive ordnance investigation serve different purposes. The proposed geotechnical method alone therefore establishes neither a suitable nor an already completed explosive ordnance procedure.

Assess historical documents

Coordinate the private service with the authority investigation procedure

For a private contract, the permissible activity and necessary permissions are checked within the specific North Rhine-Westphalia procedure. The competent bodies receive a traceable reference to the intended measure. A public announcement of another party's preparatory works does not replace this coordination. The specific contract receives a clearly defined scope and identifiable prerequisites.

Compare investigation methods
Project types

Record each phase with its associated groundworks

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

Identify investigation points clearly

A plan shows the proposed points with their current identifiers. Add the investigation purpose and planned interventions so the specialist task is clear. Earlier point numbers are cross-referenced when changes occur. A mere list of coordinates does not describe all works needed to establish and use each point.

Document investigation points and work scope
Illustration: two people with a tablet beside a drawing table and a survey trolley on a construction site.

Treat access routes and setup areas as a task in their own right

Describe whether existing routes will be used unchanged or additional groundworks are planned. A required access route is not covered solely by an investigation point beside it. The actual interventions are therefore shown on the plan. Their technical assessment uses the available information and the specific execution planned.

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

Define later construction sections in good time

The construction design may require different areas and depths from an earlier investigation. Record these differences in the document overview from the outset. A later contract can then build specifically on the available information. A completed preliminary investigation package is not used as evidence for a subsequently defined overall construction project without comparison.

Document findings and their limitations
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 Ahlen contract, the first step is to identify which ground investigations or associated preparatory works are planned next. Points, depths and working areas required are linked to the available explosive ordnance documents. This establishes whether documents must first be assessed, specific ground volumes investigated or previously assessed findings investigated further. The permissible appointed service and required results are given this scope. An excavation defined only later remains identifiable as a separate future task. The preliminary investigation's required result is not equated with a general conclusion about the whole future construction area.

Define the specialist task

Coordinate preparatory work with the investigation

Before the investigation date, actual measurement access, utility information and interfaces with other trades are clarified. Access routes and setup areas are also described in terms of any groundworks planned. The preparatory works needed depend on the method and site. Additional breaking-out or other interventions to create investigation access are coordinated technically with the responsible participants in advance, not undertaken independently. Point investigations and the further working areas they require remain identifiable with their respective prerequisites.

Clarify preparatory work in the programme

Agree a clear scope and schedule

The appointment describes the preliminary investigation initially planned and the information known for it. Partially accessible areas and outstanding prerequisites are considered in the scope. Effort and dates depend on actual access, documents and coordination; evaluation and result handover form part of the process. If the later construction design is still undecided, this is expressly stated. Changes to investigation points or associated groundworks are compared with the agreed contract. The next step can thus be prepared without extending point-specific results to all future works.

Discuss the scope and schedule
Tasks at the site

Bring together the investigation programme and areas required

01

Mark the points on the plan

Number the proposed investigation points and plot their locations on a common drawing. A parcel number alone does not describe where the ground will actually be disturbed. The review must also show which points have been added or moved compared with an earlier design.

02

State the depth for each investigation point

Different investigation tasks may require different depths. State the planned intervention depth for each point and the elevation reference used. If ground levels change, the comparison must remain traceable. A known result for a shallower intervention does not support conclusions at arbitrarily greater depths.

03

Consider associated works

If a setup area must be created for equipment or an access route established through ground disturbance, this work also belongs in the coordination. Simply passing along an existing route differs from altering it. The actual works matter, not just their description as access or site facilities.

04

Keep the later construction design separate

Identify which drawings concern only the investigation programme and which already show the planned construction. This makes the scope of a result visible. If a few investigation points are followed by a full excavation, its investigation requirements must be assessed separately using the available information.

Project documents

Documents that establish the next step

Hand over investigation results with the point plan

Each report is kept with its associated plan version, the areas actually worked and its limitations. Moved or omitted points remain traceable. Subsequent planning can then check which conclusion is relevant to the new intervention. A summary project name does not replace this spatial assignment.

A document overview links file name, date and investigation purpose to the associated points or areas. The result report includes the maps and attachments showing the actual work scope. A simple point list and a spatial investigation boundary serve different purposes. If a map is missing, it is requested specifically. Relocated or unworked points also remain identifiable in the handover. The assessment can then be checked against the investigation programme actually completed. The project file also records which works were actually carried out. A clearance record is assigned to its associated clearance operation and the area worked.

Document the transition to construction design

The later execution receives its own overview of the evidence required. Existing results are considered there with their original purpose. Outstanding areas and depths remain visible. The construction management team can thus understand the current information without inferring a wider investigation scope from completed preparatory works.

Before a later construction phase, foundations, excavations, utility routes and working spaces are compared with the documented investigation scope. Additional depth or a laterally changed intervention is shown specifically. The resulting technical question is assigned to the area concerned. The design records which information can already be used and which additions are still needed. When contractors change, this information is handed over with the complete reports. A new participant can then work from a traceable state of progress.

Construction sequence

Coordinate investigation and construction sections

Start with the current investigation plan

Bring together the point list, planned interventions and available explosive ordnance documents. Identify associated access routes and additional groundworks. Outstanding information is assigned a contact person for clarification. This overview allows the next technical step to be determined without pre-empting undecided parts of the later construction works.

Coordinate the construction phase with us

Check changes before execution

If a point is moved or the planned depth changed, this is compared with the previous conclusions. The change remains identifiable on the plan and in further coordination. Necessary additions relate to the new scope. Only then can the result package be assigned to the work step actually to be carried out.

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 analysis and other older documents help to locate the basis for suspicion spatially. Available images, their evidential value and area boundaries are related to the proposed investigation points and associated working areas. The absence of a visible finding is not a technical investigation of today's ground. The assessment is brought together with other information. The geotechnical question and historical explosive ordnance assessment retain their own information bases. If the later construction design changes or expands, it is checked whether the existing assessments cover the ground volumes actually required.

Understand aerial photograph assessment

Magnetometric survey

Magnetometric methods detect magnetic anomalies. Suitability is assessed according to expected objects, ground conditions, interference and investigation volume required. Utilities, fences and existing structures can affect interpretation. Signal strength alone does not identify explosive ordnance. Measurement, assessment and further investigation are planned for the specifically defined preliminary investigation task. Results receive location references and limits of their conclusions. An investigation of individual points is not used as evidence for the whole future construction area merely because those points lie within the property.

Understand the scope of magnetometry

Electromagnetic methods

Electromagnetic investigations may be suitable for certain metallic target objects and site conditions. Selection considers the conclusion required, accessible measurement areas and interfering installations, not just instrument availability. Results receive location references and details of the actual investigation conditions. Any necessary supplementary method follows from technical assessment. The ground volume worked is assigned to the planned investigation points and working areas. Changed points are compared with this actual result scope before execution.

Understand electromagnetic surveying

Ground-penetrating radar

Under suitable conditions, ground-penetrating radar can provide information about subsurface structures and reflections. Ground, moisture and installations affect interpretability. A reflection is not automatically explosive ordnance; an area without anomalies does not confirm conditions at any arbitrary depth. Technical interpretation and limitations are documented with the contract. Before a radar report for geotechnical or other purposes is used as explosive ordnance evidence, its objective and scope are checked. The actual coverage is related to the ground volume needed for the preliminary investigation.

GPR and limitations

Deep-ground and downhole surveys

For deeper interventions, it may be necessary to check whether a surface investigation achieves the required conclusion or another approach is needed. Proposed investigation positions and depths are prepared with reference elevations, borehole arrangement and known utilities. Creating suitable investigation access is also technically planned. A standard grid or general depth figure does not replace this task. Results remain bound to the ground volumes actually worked and the method used. A geotechnical borehole description alone does not document a prior explosive ordnance investigation.

Prepare deep interventions

Survey during construction

If a necessary preliminary investigation cannot be completed in full, it is assessed whether a technically planned approach during the works is suitable. Investigation, interpretation and communication of findings are linked to the preliminary investigation or construction activities actually planned. Mere visual observation of excavated material does not replace a necessary survey. The construction management team receives the assignment of specialist works, new information and outstanding areas to the work sequence. Necessary investigations for early ground investigation points and later construction phases retain their respective scopes; they are not inferred from a mere announcement of preparatory works.

Agree the approach during construction
Technical assessment

Ground conditions and explosive ordnance are different investigation questions

Evaluate preliminary information

A historical aerial photograph analysis may provide information for the explosive ordnance assessment together with other documents. It is related to the specific area. A geotechnical description, by contrast, addresses other questions, such as ground composition. A geotechnical report must therefore not be treated as a completed explosive ordnance investigation without corresponding evidence.

For each point, location, planned intervention depth and elevation reference are provided together. A depth measured from ground level must match the ground actually present during execution. If soil is removed beforehand or a working platform created, that condition is considered during preparation. The same applies to lateral working spaces, slopes and groundworks required for setup. The point list shows which position remains open, which has been replaced and which omitted. Related plans and lists share the same traceable revision status. Existing utilities and other known installations are included in preparation with their locations. Metallic interference sources can affect interpretation; the measurement limits actually reached are described in the results report. If the requested specialist task is described as downhole clearance, the point location, depth reference and required scope of conclusions are clarified before appointment.

For investigations in sections, the order of interventions is coordinated with the information required. An access route may be used before the investigation point itself. The works planned for it therefore receive a separate description. If an existing surfaced route remains unchanged, that condition is distinguished from a construction access road that must be created. Setup areas added later are checked for coverage by the existing documents. The contractors receive the approved work plan together with the relevant specialist results and outstanding prerequisites.

Clarify the investigation before opening the ground

Whether and how a survey is required is coordinated technically before the ground intervention concerned. The proposed ground investigation equipment does not automatically determine the explosive ordnance method. Access, existing interference and the conclusion needed also form part of preparation. Independent trial excavations are no substitute for this clarification.

Use results for the next phase

The clearance plan describes the steps required for the task in question. Preliminary investigation results can inform further design but retain their spatial and depth references. As the construction design becomes more definite, they can be used to check which questions are already answered and where supplementary clarification is needed.

Next steps

From the first point plan to later execution

01

State the purpose of the preliminary investigation

Describe which design question the ground investigation programme is intended to answer and which groundworks are planned for it. Attach the complete existing explosive ordnance documents. A brief reference to an area already checked is insufficient if the associated report or map is missing. Initial contact identifies the responsible people, current plan version and the first works due.

02

Coordinate the investigation scope

Have the proposed points and associated works compared with the available information. Authority requirements must be considered. Record which prerequisite must be met before a particular investigation point is opened and which questions remain for the later construction phase. Where necessary, outstanding historical information is researched and technically assessed using suitable records and photographs. The required official aerial photograph assessment is initiated through the locally competent body. Methods and investigation scope are then selected according to target objects, ground, depth, interference and access. Works required for setup and access are also considered.

03

Check relocations before execution

A point may need to be moved on the plan, for example because a utility occupies the intended location. Report such changes before the intervention. Whether the previous result covers the new position must be checked against its actual limits; an unchanged point number alone says nothing about this. Once the prerequisites are clarified, the agreed investigation or technically suitable supervision is performed. Data and observations are evaluated for their significance to the intervention described. Usable results, anomalous findings and outstanding questions remain distinguishable.

04

Hand over preliminary investigation and construction separately

After the investigation, document which areas and depths were worked. Also pass limitations to those continuing the design. Before later groundworks, the execution plan current at that time is compared with these documents so that a limited result is not accidentally used for a larger area. The follow-on decision identifies additions or coordination needed before the next work step. For tendering, the specific specialist task and expected result documents are described.

Documentation

Results must belong to the right design phase

Findings and their scope

Traceable evidence connects the area investigated, works performed and their result. For point investigations, assignment to the identified points is particularly important. Areas that could not be covered must also remain identifiable. Keep the underlying plan version with the report and mark later changes.

Project responsibilities

FONTANA-EOD performs the agreed specialist contract. Authority decisions remain with the competent bodies; in North Rhine-Westphalia these include local public order authorities and state explosive ordnance disposal services. The BFR Kampfmittelräumung apply directly to federal properties and offer technical guidance on planning and documentation for other projects.

Working approach

How FONTANA-EOD works

Document the agreed specialist service clearly

FONTANA-EOD performs the agreed specialist task for the identified Ahlen investigation points and working areas. Accessible areas and results required are coordinated before execution. Changes to the design or local conditions are reviewed before the works affected. The report documents the actual work and its limits. Subsequent designers can identify which conclusion is available for the next investigation point and which questions can only be addressed with the later construction task. An announced investigation is distinguished by its actual progress from a result that has been handed over.

Discuss the investigation task

The task before the equipment

Method selection starts with the information required for the ground investigation immediately planned. The specialist designers consider existing results, subsurface conditions and actual circumstances. An available instrument or a similarly completed neighbouring borehole is insufficient as the sole basis. Selection is justified for the ground volume described. The explosive ordnance question remains distinguishable from the geotechnical information to be obtained through the subsequent investigation.

Keep limitations visible

Inaccessible areas and those with limited interpretability are identified with their actual boundaries. The construction management team can assign the affected investigation works and additions still required to them. A general total-area figure does not replace this distinction. Design and execution teams coordinate when a suitable investigation will be possible. Associated access or setup areas also remain identifiable where groundworks are planned. A result for an individual point is not silently transferred to these further volumes.

Clarify changes before intervening in the ground

New positions, additional depth or different construction methods are compared with existing results before the work concerned. The specialist designers receive an identifiable description of the change from the previous investigation stage. Their response and necessary additions are assigned to the ground volume affected. This also applies when an early investigation develops into a definite excavation or route design. The same property address or continuing project name does not in itself confirm an unchanged investigation task.

Hand over the report and plan together

Reports and plan attachments are handed over with the investigation points and working areas actually worked. An overview may identify the conclusions and outstanding tasks important for the next step. It does not replace the documented investigation scope. When designers, construction managers or contractors change, the bases of the early investigation remain traceable. For subsequent construction, it is checked which results fit and which additional ground volumes still need separate specialist clarification.

Understand the results

Use technical statements for the next decision

An announcement describes intended works

A published advance notice does not show which investigations were subsequently completed. The corresponding result documents are needed for that. Naming a property in a list also initially describes the intended reference. Only the documentation shows the work scope and associated conclusions.

Understand investigation reports and their limitations

Distinguish an investigation point from its working area

An individual point may belong to a larger work task. What matters is which additional groundworks are planned for execution. These are described separately and compared with the available information. An access route used unchanged and an area that must be created are not equated solely because they serve the same project purpose.

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 investigation works in Ahlen

Does the Corridor B notice provide evidence for my property?

No. Ahlen's Official Gazette of 24 January 2025 announces certain preparatory works for another party's project and a period in the past. It confirms neither their execution nor a completed investigation of your project. What matters is the results actually available and their respective limits. Coordinate the investigation requirements before the planned ground disturbance. The local public order authority and the state service clarify the authority requirements within their respective responsibilities.

Does a point investigation apply to the whole future construction area?

That cannot be inferred from the property's name. What matters is which area and depth were investigated and which conclusion the report supports. Compare the result with the later construction plan before using it as a basis for further groundworks. The method used, ground conditions and local interference limit the conclusions for additional areas or depths.

Must access routes appear in the documents?

Describe the access routes needed for the preliminary investigation, particularly any groundworks planned there. Whether an additional investigation is necessary depends on the specific intervention and available information. An existing route used unchanged and an access route that must be created are not the same task.

What should be done when a borehole point is moved?

Mark the new position and clarify before the intervention whether it is covered by the previous investigation result. Also record changed depths. A point must not be considered resolved merely because it retains the same number on the plan.

What should I do if I find possible ordnance?

Stop the affected works and move away from the object. Do not touch or move it and keep other people away. From a safe distance, notify the police immediately on 110; further steps follow the authorities' instructions.

What does the next design phase need from the preliminary investigation?

Complete reports with a point plan, work scope and limits of the conclusions. These details are compared with the newly planned areas and depths. The specialist process connects document review and necessary historical assessment with method selection, investigation, evaluation and documentation. Follow-on works are related to the information actually available from that process.

Which factors determine effort and costs?

The method, number and location of points, investigation scope, depth, interference and access determine the effort. Missing documents or necessary preparatory works are considered during coordination. The appointment agrees the specific specialist task and required result documents with their scope. Allocation of costs is clarified with the responsible participants within the respective procedure.

How are omitted or relocated investigation points handled?

They remain traceable on the plan. Results from other points are not transferred to them; further requirements are clarified for the current location and task. An announcement is distinguished from final evidence using the works actually performed and their result documents.

Project enquiry

Prepare the first technical discussion

Show points and working areas

Mark investigation points, additional groundworks and the respective plan version. Add the project address, parcel, complete explosive ordnance reports with their maps, authority correspondence and available utility plans. The sector overview explains typical interventions and the documents they require.

State the construction phase

State whether you are preparing the next preliminary investigation or already the later construction works. Identify the earliest intervention, additional areas, inaccessible areas and the people responsible for queries.

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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