Technical map view of the Gießen administrative district with Gießen marked for explosive ordnance assessment and surveying by FONTANA-EOD

Explosive ordnance surveying for your construction project in Wetzlar

A suspected location lies beside the planned construction site. Can it be disregarded in the explosive ordnance assessment? For a project in Wetzlar, the technical assessment needs the precise location, proposed ground works and associated statement. The property boundary alone does not answer that question.

Location

Locate suspected points on the correct plan.

Construction area

Define the full extent of proposed ground works.

Coordination

Clarify access and outstanding questions early.

Discuss the project's technical requirementsExplosive ordnance assessment in Hesse
Assess the construction project

How is a suspected location near the construction site assessed?

For a project in Wetzlar, the existing statement, its location plan and proposed ground works are considered together. Indications on adjoining land may also matter. The investigation brief identifies the affected areas and unresolved access; existing results reports are taken into account within their actual scope.

Project site

Identifying Wetzlar and the actual project location

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

Reading the subsequent ‘Schattenlänge’ planning status too

The explanatory statement dated January 2021 also reports on page 14 that the entire plan area, including the rainwater retention basin, had since been investigated and certified free from explosive ordnance. The suspected hazard information reproduced earlier therefore describes an earlier stage of work. For your project, the complete associated evidence is compared with your own current plans.

Wetzlar is the district seat and a special-status town within Lahn-Dill-Kreis in the Gießen administrative district in Hessen, Germany. State the actual project address and municipality. For a project in the surrounding area, local responsibility follows that project location. The explosive ordnance clearance service at the Darmstadt regional administration is responsible throughout Hessen. Further tasks and access are agreed with the respective responsible bodies or parties.

Hesse
Local context

Considering suspected locations together with the site and evidence

Reading the statement at the time in its full planning context

The explanatory statement for Wetzlar development plan Münchholzhausen No. 8, ‘Schattenlänge’, dated January 2021, refers to an explosive ordnance clearance service statement of 24 February 2014. It identifies several suspected unexploded bomb locations and requires their assessment before construction involving ground disturbance, including where a point lies within a radius of 15 metres outside the construction site. This is a specific statement for the planning described there, not a general distance rule for every property in Wetzlar.

On the following page, the explanatory statement reports that the entire plan area, including the rainwater retention basin, had since been investigated and certified free from explosive ordnance. For a construction task today, the complete results documentation and your own proposed ground works must therefore also be considered.

Describing today’s construction task in full

Your project needs the full spatial context. An extract ending at the property boundary may hide important indications from the statement. Provide the available plans together with the current construction plans. FONTANA-EOD helps define the specialist task and any coordination required.

The municipal old town framework plan describes Wetzlar as an industrial location exposed to heavy bombing during the Second World War, particularly around the railway station and in Niedergirmes. At the same time, a substantial part of the historic urban structure survived within the medieval town walls. For a project today, this historical context is compared with the available site-specific findings and known later changes. A specific investigation remains tied to the current construction task and the ground volume actually assessed.

Working together

Distinguish the tasks of client, designers and specialist contractor

Client and operator

The project owner describes the proposed work and provides the available project documents. The operator adds requirements for use, access and timing. A coordinating contact makes cooperation easier but does not automatically take on every other party's duties. Before commissioning, record clearly which information is missing, who will obtain it and which decision the result is intended to support.

Planning and construction management

The specialist designers describe areas, depths, construction methods and changes. Site management coordinates the planned sequence with the construction contractors and agreed specialist works. Results are assigned to the respective intervention. A technical plan change is communicated early enough for its effect on the survey task to be assessed before construction. Organisational construction stage boundaries remain distinguishable from technical survey boundaries.

Specialist company and competent bodies

The private explosive ordnance specialist carries out the agreed investigation and documentation. Official requirements and decisions are clarified with the competent bodies. Documents needed for a specific procedure depend on the site and project. The technical report describes the specialist work completed with its spatial extent and limits. Its applicability to further groundworks is checked against the specific ground disturbance. The competent bodies make official decisions.

The KMRD based at Darmstadt Regional Council is responsible for all of Hesse. Suitable specialist contractors are commissioned for technical investigation or clearance within the respective permit and competence framework. Under Hesse's General Provisions, defusing, blasting and removal are reserved exclusively to the KMRD or a person commissioned by it. Assign the competent authorities and responsible specialists clearly before the task concerned.

Investigation task

Which specialist task comes next?

Defining the outstanding question before selecting a method

First establish whether the task concerns an individual suspicion, a larger area or changed ground works. Existing findings and the conclusions actually needed are then brought together. A map mark alone does not determine a technical method. The objective, scope and local conditions must fit together.

Selecting methods for the specific investigation question

Accounting for survey limits during planning

Utilities, structural remains and available access may affect the investigation scope. Specialist planners describe these prerequisites and possible limitations. Areas with insufficient coverage remain identified in the results. The next steps are determined for the specific ground works; general observation does not replace a required technical assessment.

Compare investigation methods
Project types

Retaining the spatial context through to the results

Two people discussing plans at a table beside a vehicle on a construction site.

Passing on the full location plan

An isolated extract may make it harder to relate a suspected location to the proposed ground works. Provide the complete appendix with its scale, legend and plan version. The findings it can support are assessed professionally. An imported mark remains tied to its source and gains no additional accuracy by being displayed on the new construction plan.

For an unclear mark, record whether coordinates are missing, the map is imprecise or an older reference needs to be related to the present plans. State the available accuracy clearly. Specialist planners and the specialist contractor clarify the location using suitable original records. Additional assumptions remain identified until resolved. A redrawn point gains no more precise source location from a sharper printout or different map scale.

Documenting the location plan and scope of findings
Two people with a tablet beside a marked construction area; plans lie in the foreground.

Agreeing a clear investigation scope

A point, an area and a proposed trench may describe different tasks. The brief records which question must be answered for which spatial area. Existing results are taken into account. Additional access or outstanding information is agreed with the parties before work and remains identifiable until resolved.

The offer clearly distinguishes an unresolved individual suspected hazard from further investigation of a construction area. If a service concerns several construction stages, each required part is assigned a work status. It identifies the plans available, the area accessible and the coordination still required before construction. For later additions, the additional scope is linked to the previous task so that results and invoicing use the same spatial basis.

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

Handing over the report with its location information

Site management needs the actual investigation scope together with the documented limitations. This includes the associated plans and the construction plan version used. If further sections are proposed, these records allow a specific comparison of which findings remain applicable and which new question needs specialist clarification.

For handover, keep together the plan version used, the date of specialist work and associated appendices. Preliminary information remains distinct from completed technical assessments. Each limitation is assigned to the affected area so that subsequent site management can account for it during preparation. If more contractors become involved, complete records and outstanding tasks are passed on. Even an area already investigated needs this traceable record for later ground works with different boundaries.

Document findings and their limitations
Preparation

Prepare the scope and commission together

Establish what needs to be known before commissioning the work

Commissioning establishes whether the assessment concerns an individual suspected location, an area or changed ground works. The statement and its full location plan form the starting point. The brief identifies the specific question, spatial scope and expected results documentation. Investigations already completed are taken into account with their limitations. Where access, location or further records remain unresolved, these prerequisites are explicitly identified and clarified with the responsible parties.

Define the specialist task

Coordinate preparatory work with the investigation

Work is prepared using the areas and access actually available. A neighbouring area that must be included technically is coordinated separately; a mark on a plan does not grant access. Paving, utilities and installations are taken into account in the investigation conditions. Necessary investigations and protective measures are clarified before the affected preparatory ground works. The client and specialist contractor record which prerequisites are already met and who will undertake outstanding preparation.

Clarify preparatory work in the programme

Agree a clear scope and schedule

Available contingency time and access actually agreed are recorded separately in the programme. For the construction stage needed first, identify which assessment and results documentation are required before ground works. Missing permissions or appendices remain identified as outstanding prerequisites. If a trench or access road moves, the parties receive the new plan version; the scope and timing of any necessary supplementary work are agreed accordingly.

Discuss the scope and schedule
Tasks at the site

What belongs in the investigation plan

01

Distinguishing the construction site from the property

The property describes the land owned; the construction site is the working area proposed for the project. Show both boundaries clearly. The planned ground works must also be understandable for the technical assessment. A coloured land parcel without ground works details leaves open what is actually to be investigated.

02

Using the complete appendix to the statement

Do not transfer suspected locations from an imprecise image extract to a new plan. Pass on the available original appendix with its scale, legend and version. If coordinates or the relationship to current boundaries are unclear, this requires specialist clarification. An imported mark must not appear more accurate than its source.

If older statements and new construction drawings use different reference systems or elevation information, establish the relationship before importing the marks. Include available coordinate lists and explanatory appendices. Explicitly identify known location uncertainty and missing information. A traceable working basis is then agreed for the investigation. The results retain a clear distinction between a location taken from an earlier record and the area actually covered on site.

03

Identifying adjoining areas during coordination

If the technical assessment includes a neighbouring area, access and responsibilities require separate clarification. This does not grant permission to enter another person’s property or carry out work there. Record the coordination still outstanding. The brief must not silently assume that the affected area is available.

Where needed, coordination also covers routes, site access roads and working areas outside the later structure’s footprint. Record the contact for each area and the use actually permitted. A necessary permission is distinguished from an assumed date. Where preparation requires ground works, the investigations and protective measures needed for them must be clarified beforehand. The specialist brief is related to the actual prerequisites and coordinated accordingly if they change.

04

Communicating later changes to the construction site

A moved access road or trench may change the relationship to existing suspected locations. Pass on the revised site plan before it leads to new ground works. The previous assessment must be checked against it. An unchanged project name does not mean that the spatial task has stayed the same.

Project documents

Documents that establish the next step

Accounting for neighbouring areas in project organisation

Where the specialist task concerns adjoining areas, availability and responsibilities are explicitly identified. The brief does not assume unresolved access. Record who will coordinate this and which prerequisite for the work is still missing. A reserved time slot must be distinguished from access actually made available.

The project overview shows available areas separately from those still closed or unresolved. Access provided later is compared with the investigation status at the time. An additionally affected ground volume may require a separate addition to the work. The responsible parties determine what information or specialist work is needed before its use. The new status is then brought together with the existing reports so that completed and outstanding tasks remain identifiable.

Informing the whole project team of changes

A moved trench or added access road is communicated with a traceable new plan version. Specialist planners and site management compare the change with the existing results. The report on the previous investigation is retained. The work required for additional areas is defined with its own scope. After exposure or clearance work actually completed, the associated findings and clearance records, with location and depth references, belong in the project file.

Construction sequence

Coordinate investigation and construction sections

Compiling the planning context before an enquiry

Send the statement, complete location plan and current construction plans together. Describe the proposed ground works and outstanding information. Existing results reports belong with their appendices. The specialist task can then relate to the actual area from the start and further coordination needs can be identified specifically.

Coordinate the construction phase with us

Comparing coverage before the next section

Check with the specialist planners whether existing results cover the next ground works. New areas and revised depths are shown separately. The commission adds only the specific task needed. Areas already investigated remain traceable with their documented limitations and are not extended indiscriminately to the rest of the property.

Coordinate the construction phase with us
Method selection

Select methods according to the task and survey conditions

Historical records and aerial photographs

Historical records and aerial photographs may explain the basis for a suspected location. For the Wetzlar commission, establish which analysis the mark comes from and what it indicates. Existing findings are assessed first. Any necessary research or supplementary aerial photograph analysis is commissioned for the unresolved question and actually carried out. The result is related spatially to the current plans. An earlier indication of suspected contamination and later investigation evidence remain identifiable in their chronological sequence.

Understand aerial photograph assessment

Magnetometric survey

Magnetometry measures the magnetic field passively. Detection depends on the magnetic effect of the object sought; electrical conductivity alone does not make it detectable by this method. The investigation considers the expected task, existing metal installations and accessible survey areas. A historically marked suspected location and a measured magnetic anomaly are different starting points. Interpretation brings them together with their respective spatial references and records interference and the limits of the findings.

Understand the scope of magnetometry

Electromagnetic methods

Transient electromagnetic methods, or TDEM, analyse the time-dependent electromagnetic response of conductive objects. The method is selected according to the investigation objective and actual survey conditions. For an individual suspected hazard or a larger investigation area, suitable use and the findings achievable are determined professionally. Utilities and other metal installations may affect interpretation. A signal gains its significance through specialist assessment in the specific investigation context; the report identifies the areas covered and limitations.

Understand electromagnetic surveying

Ground-penetrating radar

Under suitable conditions, ground-penetrating radar can provide information about the subsurface and anomalies. Selection considers ground composition, installations and the question the brief is intended to answer. The investigation relates to the current location and depth of the ground works. Detected structures are interpreted professionally and assessed alongside the other findings. What can be established about the construction site depends on the investigation actually completed and its limitations, rather than a site plan alone.

GPR and limitations

Deep-ground and downhole surveys

For deeper ground works, a specialist assessment establishes whether a surface investigation can provide the findings needed or whether deep or borehole surveying is required. Investigation points and the vertical reference are coordinated with the current construction plans. A moved foundation may affect a different ground volume from the previous brief. The technical evidence remains assigned to the points and depths actually investigated and the limitations of the findings. Outstanding areas and further work required are identified specifically for the next ground works.

Prepare deep interventions

Survey during construction

If a necessary preliminary investigation cannot be completed in full, further work is planned with specialist input. An explosive ordnance investigation during construction may require a coordinated sequence of investigation, necessary excavation in layers, specialist exposure and supplementary surveys. Conditions and further steps depend on the task and findings. The actual supervised work area and remaining limitations are documented. Merely observing excavation is not treated as a substitute for a required technical investigation.

Agree the approach during construction
Technical assessment

Assessing individual suspected locations and the whole construction site

Understanding the existing suspicion

The historical aerial photograph analysis can provide indications that later need targeted investigation. Such a suspected location is not yet a confirmed find. The assessment must show the basis of the assumption and the area to which it relates. The mark’s source therefore forms part of the investigation evidence.

Tailoring the investigation to the specific question

Assessment of an individual suspected location and the surveying of an entire construction area are different tasks. A result for one point does not automatically cover all further ground works. Conversely, a general area description must not obscure an unresolved individual suspicion. The investigation objective, spatial scope and expected documentation should fit together in the brief.

Explicitly addressing areas with interpretation limitations

Utilities, structural remains and other influences may limit a survey. These limitations must remain visible in the results and be considered in further planning. A clearance plan can describe the measures required. Visual observation alone during excavation does not replace a professional investigation or explosive ordnance clearance during construction.

Next steps

From the planning notice to investigation and handover of results

01

Agreeing an unambiguous plan version

Use the same traceable plan version in the enquiry and brief. Identify which points and work areas the service concerns. If further records are added later, it should remain clear which assessment they changed. This makes comparison easier for specialist planners and site management. The initial discussion establishes the project location and findings needed. Existing plans, statements and reports are checked for currency, spatial reference, completeness and gaps.

02

Address outstanding historical questions

Where historical questions remain unresolved, the necessary research and aerial photograph evaluations are actually carried out under a technically agreed commission. The KMRD statement is taken into account. Additional findings are assigned to the current groundworks area and used for investigation planning.

03

Following up outstanding coordination before work begins

Missing access or outstanding official clarification is a specific prerequisite within the programme. Identify the responsible contact and unresolved matter in the project records. An assumed date replaces neither completed coordination nor a required investigation. The suitable method is selected according to the investigation objective, ground works depth, ground composition, installations and actual survey conditions. Access and required prerequisites are clarified with the responsible parties.

04

Perform the agreed investigation

The agreed survey or appropriate investigation during construction is carried out on the defined areas and points. Measurement data and observations receive clear position and elevation references. Uninvestigated areas, restricted access and relevant interference are recorded.

05

Assess and document findings

The collected data and findings are assessed against the investigation objective and actual measurement conditions. The assessment takes account of interference and limitations. The report and plan appendices document the technical assessment, areas addressed and their position, elevation and depth references. Required further tasks follow from this.

06

Keeping results tied to the investigated area

The documentation should clearly identify the point or area and state the limitations. The word assessed is insufficient for later use. It must be possible to trace which task was carried out and whether it covers the planned ground works.

07

Checking the next construction section separately

Where work proceeds in sections, each following section needs appropriate evidence. Existing reports can be used where their spatial and technical findings apply. A completed investigation in one section does not establish that an adjoining area is unaffected without further comparison.

Documentation

Contacts for a project in Wetzlar

Findings and their scope

The City of Wetzlar recommends that project owners obtain information about possible explosive ordnance contamination before construction. It identifies the Darmstadt regional administration as the responsible authority. Where there is a suspicion, the next steps for searching and, where necessary, recovery must be clarified. This information is distinct from a result for a particular property. Official decisions are made by the responsible bodies.

The General Provisions for Hesse specify site plans at a scale of 1:1,000 and submission of results to the explosive ordnance clearance service. The technical commission, actual progress and relevant plan version remain available together in the project file. Later additions receive their own area and date references.

Project responsibilities

An enquiry to Hessen’s explosive ordnance clearance service requires an accurate plan with marked property boundaries. FONTANA-EOD’s commissioned specialist services remain distinct from official responsibilities. Outside their scope concerning federal properties, the BFR KMR provide technical guidance; the applicable requirements for your project must be considered separately.

Working approach

How FONTANA-EOD works

Document the agreed specialist service clearly

FONTANA-EOD describes the agreed specialist service by the specific investigation question. Assessment of a marked point and work across an entire construction site each receive their own spatial scope. The results make the work actually completed, findings achieved and outstanding areas traceable. Site management and specialist planners can compare the next ground works against them. A term such as assessed is made specific through the associated technical details and location plans.

Discuss the investigation task

The task before the equipment

Before choosing equipment, establish what information is needed about the suspected location or construction site. An uncertain transfer from a map extract first requires the original appendix and a traceable spatial reference. The suitable method is determined only once the investigation objective and actual conditions are established. FONTANA-EOD agrees the specialist scope needed and expected form of results; existing investigations are considered according to their original purpose.

Keep limitations visible

Limited access and areas with insufficient coverage remain identifiable in the results. If the task concerns neighbouring land, its availability is clarified separately. Until then, it is not recorded as a fully investigated part of the construction site. Further planning receives the actual scope covered and outstanding prerequisites. For the next ground works, the additional information or work still needed is established.

Clarify changes before intervening in the ground

If an access road or trench moves, the new geometry is passed on before the affected ground works. FONTANA-EOD compares it with the previous investigation areas and point locations. Any necessary addition is agreed for the ground volume actually added. The earlier report remains with its original scope. New results are assigned to a plan version and area so that the change is traceable for everyone subsequently involved.

Hand over the report and plan together

The report and location plans are handed over together. They retain a clear distinction between a service concerning an individual suspicion, an area or a specific construction stage. Identify the recipients among the project owner, specialist planners and site management. If the executing contractors change, outstanding questions and access prerequisites are also passed on. The next construction stage is compared with the documented result rather than inferring the findings from a project name or individual mark.

Understand the results

Use technical statements for the next decision

Distinguishing a requirement from evidence of completed work

A statement may describe a necessary investigation. Whether it was subsequently completed, and to what extent, follows from the associated evidence. Read the entire available file. Isolated historical paragraphs are insufficient to establish an area’s current investigation status for new ground works.

Understand investigation reports and their limitations

A boundary needs a clear meaning

The property boundary, investigation area and proposed work area serve different purposes. They are shown distinctly on the site plan. The technical comparison considers precisely these relationships. A new coloured outline changes neither the documented investigation scope nor responsibility for adjoining properties.

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 suspected locations and construction site boundaries

Can I leave out a suspected location outside my property?

Not solely because it lies outside the ownership boundary. Its relevance to the proposed ground works must be clarified from the specific statement, location and technical assessment. Necessary work on other properties requires separate coordination.

Does the 15-metre distance in Schattenlänge apply throughout Wetzlar?

No. That detail forms part of the explanatory statement for Münchholzhausen No. 8 and the statement used as its basis. For another project, its own records and the specific official or technical assessment are decisive.

Does marking a suspected location establish that a bomb has been found?

No. A suspicion mark indicates an assumption to be clarified. The result of a specialist investigation is distinct from this and must be clearly assigned to the area concerned.

What should I do if the planned trench moves?

Pass the revised plan on for specialist assessment. It must be clarified whether the existing investigations and assessments still cover the new work area. Where necessary, outstanding tasks must be addressed before the changed ground works. Existing measurements apply only to the areas and depths actually covered. If utilities or metal installations limit interpretation, outstanding areas and additional investigation needs are identified separately.

What should I do if I find an item unexpectedly?

Stop work, leave the object where it is and keep others away. From a safe distance, call the police on 110. The City of Wetzlar identifies the police and explosive ordnance clearance service as contacts; follow the authorities’ instructions. Do not touch or move the object, expose it further or take it to a police station or other official premises. Leave the danger area and keep others away.

Why should the later status recorded in the planning documents also be considered?

Because an earlier requirement may already have been addressed later. The complete results documentation shows the scope completed and is compared with the new ground works.

Does including neighbouring land in the technical assessment automatically permit work there?

No. Access and any necessary work must be agreed separately with the responsible parties.

Which cost factors matter for an investigation in Wetzlar?

The work involved depends on usable statements and complete location plans, existing results reports, the nature and scope of the outstanding question, area size or number and depth of investigation points, required access and preparation, the suitable method, survey conditions, interpretation and documentation. Neighbouring areas needing clarification or changed ground works are accounted for in the actual scope of services. Private specialist work, official responsibilities and other preparatory services remain distinct.

Project enquiry

Prepare the first technical discussion

Include the complete file

Provide the statement, location plan and later results reports together.

Add the precise project address, land parcels, marked current site plan and the decision needed. Include the complete statement and its location plan, together with later investigation reports and appendices. State the source and version of suspected location marks. Describe ground works, depths, routes, borehole positions and additional working areas. Known ground changes, existing utilities and available aerial photograph analyses form part of the initial information. Missing details remain identifiable for further clarification.

Show current ground works

Mark the construction site, depths, changes and unresolved access.

Identify the client, planners, site management and coordinating contact. State the desired programme and sections needed first. Mark later access and adjoining areas whose availability remains unresolved. Provide existing official conditions, utility plans and project status. Where several trades are involved, record who will provide new plan versions and bring together complete results before the next ground works. Changes are identified by date and affected area.

GPR on a construction site
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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