Technical map of the Leine-Weser administrative area marking Hildesheim for explosive ordnance assessment and surveying by FONTANA-EOD

Explosive ordnance surveys in Garbsen

For explosive ordnance assessment of your construction project in Garbsen, we need a site plan with the proposed ground works and reports already available. This also includes utility connections and temporary site areas. FONTANA-EOD clarifies with you which investigations are needed and what must be coordinated with planners, utility providers or authorities.

Agree the plan version

Compile current plans and existing reports.

Describe connections

Identify areas, depths and contacts.

Outstanding tasks

Record who provides missing information or results.

Discuss the construction project and investigation needsExplosive ordnance assessment in Lower Saxony
Assess the construction project

Plan buildings, connections and preparatory earthworks together

A construction project often involves more ground works than the later building footprint. For your project in Garbsen, we also record connections, working areas and temporarily used areas. The investigation scope and responsible contacts are clearly assigned before each ground intervention.

Project site

Connect the site with the specific construction task

Illustration of a map with the Lower Saxony coat of arms, a tablet, hard hat and documents.

Site and existing requirements

Specify the actual project location with a site plan and the affected land parcels. Existing information, conditions and reports are assigned to this area. Garbsen is in the Hannover Region in Lower Saxony. The Hannover Region belongs to the Leine-Weser administrative area. The actual project address is decisive; where work crosses municipal boundaries, the respective responsible municipal bodies are involved. Identify the version of the records and the body responsible for the project location for each site plan.

Explosive ordnance assessment in Lower Saxony
Local context

Relate earlier Garbsen records to the construction project

Coordination with those involved

According to its building advice information, the City of Garbsen offers building application conferences for larger projects, involving utility providers and specialist authorities. For a consultation, the site or project concerned should be identified in advance. Whether and how such a meeting would be useful for your project is agreed with the city.

Documented planning status

For the area covered by Amendment 156 to the land-use plan in Stelingen, the explanatory statement with a planning status of July 2023 identifies an LGLN aerial photograph analysis. No explosive ordnance contamination was suspected; according to this document, no survey had been carried out. Bring the actual analysis and area plan to the project discussion. Check whether it covers your construction area, including connection routes and temporary working areas. Which further investigations are needed must be clarified from the specific records and planned ground works.

Compare present ground works with earlier location information

The location of the proposed building alone is insufficient for explosive ordnance assessment. The proposed earthworks, connections, working areas and existing findings are also needed. These records allow clarification of the investigations to commission and questions still to be addressed to the responsible bodies.

In his recollections published by the city, Karl-Heinz Strehlke describes a searchlight position near Havelser Mühle. For a present-day investigation, such location information is brought together with further records, maps and later changes to the ground. A historical recollection provides a lead for research; the specialist assessment concerns the construction area actually affected.

Compare earlier municipality and district names with the current project address and land parcels. The project file records the original name, associated period and present spatial assignment. This supports comparison of older plans with connection trenches, boundary strips and temporarily occupied working areas. Spatial information not yet clarified is checked specifically before further investigation.

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 contractor performs the agreed investigation and documentation work. Official requirements and decisions are clarified with the respective responsible bodies. The records needed for a specific procedure depend on the location and project. The technical report documents the specialist work carried out and its area, depth and limits of conclusions. The responsible bodies make official decisions concerning subsequent groundworks.

For a project in Garbsen, municipal requirements are agreed with the body responsible at the project location. The state explosive ordnance disposal service supports Lower Saxony’s municipalities within its remit.

Investigation task

Which specialist task comes next?

Bring plans and investigation results together

Publicly available land-use plans help establish spatial context. Explosive ordnance assessment also needs the relevant analyses, reports and official correspondence. In particular, check whether their appendices cover the proposed ground works outside the building too. Missing records are obtained specifically; an appendix that cannot be found does not itself establish a particular technical measure.

Assess historical documents

Define investigation for the outstanding areas

The remaining task is identified by comparing the construction plans with existing results. Access, installations, terrain and required depth influence the appropriate method. The brief should clearly identify the sections to be covered and findings needed. The contractors involved can then relate their subsequent work steps to a traceable investigation scope.

Compare investigation methods
Project types

Clarify transitions between construction tasks

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

Buildings and utility connections

The building plan does not necessarily show every connection pit and utility route. Also show connections up to their proposed handover points. Each section must identify who provides the plans and which investigation already exists. A report on the building construction area may contain important findings without covering all connections outside it. This spatial assignment is checked before commissioning.

Add the proposed trench profiles, connection pits and side working spaces to the route plan. The utility depth and required excavation depth may differ. The ground volume actually affected is described for the investigation. Where two investigation areas meet at a handover point, their boundaries and depths are checked using the complete plans. The contractor thus receives an unambiguous basis for that connection.

Specialist services and investigation tasks
Illustration: a person wearing a hard hat and holding a tablet beside a cordoned-off excavation with an excavator.

Site facilities involving their own ground works

Temporary access roads, edging, connections to site cabins or preparatory drainage may begin before the foundations themselves. The specific work proposed and its depths are decisive. A simple area label such as site facilities is insufficient. If areas are initially used without ground disturbance, this must also be distinguished from later earthworks. The programme should clearly show these differences to all involved.

A preparatory work commission should identify whether it concerns only use of an existing area or, for example, removal of paving, construction of an access road or installation of drainage. For work involving ground disturbance, locations, depths and sequence are identified. The explosive ordnance prerequisites are clarified before that step. Agree when the area will be accessible for investigation and who will make it available. If preparatory work changes the terrain, the new conditions are considered in the further investigation sequence.

Provide specialist supervision of excavation
Illustration: two people review plans and documents at a table beside a construction vehicle.

Several clients on adjoining areas

A utility company, property owner and contractor may commission different parts of the work. Agree who obtains the necessary records, confirms the investigation scope and receives the results. Shared maps make this coordination easier. They do not replace complete reports or unambiguous assignment of a commission. Outstanding transitions between sections remain visible until clarified.

On the shared site plan, distinguish property boundaries, service scope boundaries and existing investigation boundaries. These lines may lie in different places. For each connection area, record which commission covers it and who receives the complete report. When the contractor changes, the relevant records are handed over with their plan version. Outstanding sections remain identifiable as separate tasks.

Coordinate the sequence and tasks
Preparation

Prepare the scope and commission together

Establish what needs to be known before commissioning the work

First establish which decision the commission needs to support. Is the task an initial assessment of existing documents, an investigation of a specific area or examination of an anomaly that has already been assessed? These tasks require different evidence. A general wish for safety does not define an investigation that can be carried out. The enquiry therefore specifies the groundworks, location, depth and available findings. Suitable specialist work and the required reporting are then agreed on that basis.

A tender describes the respective scopes of document review, necessary analysis, technical investigation and handover of results. Identify existing information and services whose necessity can be established only after specialist assessment. This makes clear which work can already be offered and which prerequisites need clarification first. Quotations relate to the same areas and proposed ground works.

Define the specialist task

Coordinate preparatory work with the investigation

Required access and survey conditions are clarified before the site visit. This may include keeping areas clear, obtaining service information and coordinating with other trades. The method and site determine which preparations are actually needed. Changes to the surface or additional groundworks are not undertaken unilaterally simply to prepare for a survey. Their sequence is agreed with the specialist designers and responsible parties.

Also clarify who makes access to a connection area possible and who coordinates with owners or operators. An available appointment on the main construction site does not yet provide access to the utility route outside it. Before work begins, the contractors affected need the same access and utility information. If local conditions change, further steps are agreed with those responsible.

Clarify preparatory work in the programme

Agree a clear scope and schedule

A reliable process distinguishes work already technically clarified from prerequisites still unresolved. If an area will only be partly accessible, this must be taken into account when commissioning the work. Handover and assessment of results also need time in the construction programme. Specific coordination connects the described scope with access, records, execution conditions and the date by which a decision is needed.

Discuss the scope and schedule
Tasks at the site

Which ground works belong in the plans?

01

Buildings and external works

Show foundations, basements, drainage and other earthworks together. Check whether the planners involved are assuming the same depths for the same areas. The explosive ordnance assessment brief must identify the ground works actually to be carried out and information still provisional.

02

Utility connections

Describe utility corridors, connections and possible ground works outside the construction site itself. Identify the responsible utility provider and include available as-built plans. Check separately whether existing explosive ordnance investigations cover the proposed connection trench.

03

Site access roads and temporary utilities

Where site access roads, temporary utilities or other facilities involving ground disturbance are proposed, include them in the overview. These temporary ground works must also be considered for explosive ordnance assessment. The time when these areas are first to be used is particularly important.

04

Who commissions which area?

Specify which commission covers which ground works. If a commissioned investigation ends at the property boundary, the connection outside it remains to be clarified separately. Record who arranges investigation of the connection area and who receives the results.

Project documents

Documents that establish the next step

Establish a shared record of the areas

Bring building areas, connection routes and preparatory ground works together in a coordinated overview. Add the proposed depths and technical reports available for each. Those involved need the same plan version when describing their service scopes. Changed handover points or additional working areas are added with dates so that no investigation relies on an outdated spatial assumption.

Link coordination outcomes to responsibilities

Record which technical question has been clarified, which document is still missing and who prepares the next decision. Meeting minutes can organise these tasks. Whether an area was actually investigated and what it establishes remain matters for the associated technical report. After clearance work, the clearance record with the actual scope and results is additionally assigned to the areas covered and relevant site plan. Before the next ground intervention, it is checked whether the contractors have received the results needed.

Construction sequence

Coordinate investigation and construction sections

Before the first connections are installed

The earliest earthworks determine when records and technical decisions must be available. This may be a utility connection or temporary drainage before building construction. Show the actual sequence. Required plans, access arrangements and handovers of results are assigned to these work steps. A later investigation of the main construction area does not retrospectively cover ground works begun earlier outside it.

Coordinate the construction phase with us

If a handover point moves

A changed connection point may require a different utility route and new working areas. Pass the change to the specialist planners before work begins. They compare the new ground works with existing results and describe any additional investigation needed. The affected parties then receive the updated plans and associated findings. Even an unchanged construction project may thus involve individual new investigation questions.

Coordinate the construction phase with us
Method selection

Select methods according to the task and survey conditions

Historical records and aerial photographs

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

Understand aerial photograph assessment

Magnetometric survey

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

Understand the scope of magnetometry

Electromagnetic methods

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

Understand electromagnetic surveying

Ground-penetrating radar

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

GPR and limitations

Deep-ground and downhole surveys

For deeper groundworks, it may be necessary to establish whether a surface investigation can provide the required findings or another approach is needed. Preparation includes the location, depth, borehole layout and existing services. Creating access for the investigation must also be properly planned by specialists. A general depth figure or standard grid cannot replace that work. Findings remain limited to the areas actually investigated and the method used.

Prepare deep interventions

Survey during construction

If a necessary preliminary investigation cannot be completed, it is assessed whether a technically planned approach during construction is suitable. This includes coordinated investigation, interpretation and communication of findings within the planned workflow. A necessary survey remains part of the agreed approach; visual checks supplement it. Site management needs a clear description of when specialist work takes place, how new findings are handled and which areas remain unresolved.

Agree the approach during construction
Technical assessment

Clarify records, methods and responsibilities

Geoportal and explosive ordnance records

The Garbsen geoportal provides spatial information; the city’s explanation identifies development plans, among other information. Such maps help with spatial orientation but do not replace explosive ordnance records. An aerial-photo analysis requires a clearly defined application area. Its result must be assessed separately for the planned ground works.

The comparison needs complete explosive ordnance reports with their appendices. Record whether the document covers a historical analysis, a survey carried out or further work. Each report must identify the area investigated, plan version and, where relevant, level reference used. Missing appendices are obtained before a short result statement is used to decide about a new connection or deeper excavation.

Survey conditions on the construction area

For necessary surveys, describe the actual site conditions: access, existing utilities, paved surfaces and other influences on the investigation. The geophysical survey must match the investigation objective and these conditions. The method must be defined by specialists before work begins.

For an enquiry about borehole clearance, the proposed borehole position, maximum drilling depth and associated ground or reference level are needed. State whether the borehole position may still move and which other ground works are required for equipment positioning or access. The specialist planners use this to determine the suitable explosive ordnance investigation. Its documented findings remain tied to the ground volume covered; the later borehole is compared with this scope.

Tasks of the specialist contractor and authorities

Lower Saxony’s division of responsibilities separates commissioned hazard investigation from official measures by the municipality and the state KBD’s tasks. A clearance plan can bring together the required services and coordination. Official decisions remain reserved for the responsible bodies.

Where a technically planned investigation during construction is agreed, the construction plans describe the work sequence, investigation sections and required assessments. Visual checks supplement the proposed technical investigations. Before the next soil removal, site management and the contractor receive the necessary information. Authority to issue instructions and reporting channels are agreed before work begins. If a suspicious object is encountered, affected work stops and the responsible bodies are notified immediately.

Next steps

How to prepare the project discussion

01

Prepare the initial discussion with current records

Bring together the current plans, existing explosive ordnance records and known official requirements. Mark provisional information. For each proposed ground intervention, describe at least the area and depth as far as the planning stage allows. The initial contact identifies the exact project location and first proposed ground works. Existing aerial photograph analyses, survey reports and official correspondence are compared with the building, connections and working areas. The document review shows which findings can already be assigned and which information is missing.

02

Assess outstanding historical questions and aerial photographs

Where the evidence for the area concerned is unresolved, the necessary historical research and wartime aerial photograph analysis are carried out. Earlier location information, uses and changes to the ground are related to the present ground works area. The analysis describes its findings and limitations as a basis for subsequent investigation planning.

03

Define methods and necessary preparatory work

Record which question requires specialist investigation and which must be clarified by the planners, utility provider or authority. Identify the contacts for each. Discuss the outstanding questions for the specific proposed ground works. The explosive ordnance planners select the suitable method according to the investigation objective, depth, ground structure and interference. Different connection and building areas may need different approaches. Access, necessary preparatory work and coordination with utility providers are clarified before work begins.

04

Investigate and assess anomalies

The commissioned survey or technically planned supervision is carried out in the described area. Survey data and anomalies are assessed professionally according to the method and local conditions. Inaccessible sections and further clarification needed remain spatially identifiable. If a suspicious object is encountered, affected work stops and the responsible bodies are notified.

05

Hand over complete technical reports and associated plans

The minutes should distinguish between decisions made, work assignments and outstanding questions. Record which documents must be supplied later and who receives them. Official decisions and investigation reports must exist as separate documents. The investigation documentation records the actual work with areas, depths, methods and limitations. The report and associated plans are handed over together to the named recipients. The project file retains an identifiable record of the specific findings available for the next construction phase.

06

Compare the following ground works with the result

If a foundation or utility route changes after coordination, the change is submitted to the specialist parties affected. It must be assessed whether the previous task definition remains sufficient. Clarify necessary additions before the changed ground works. Before the next ground intervention, it is checked whether the documented result covers the location, depth and working method. Specialist work and coordination with the authorities still needed are assigned a specific next step. The relevant records are passed to the next contractor.

Documentation

What the investigation report must contain

Findings and their scope

A technical report should identify the area and plans to which the result applies. Associated plans, investigation boundaries and limitations must be retained when passed to site management and utility providers. Hand over the complete report with its appendices.

Project responsibilities

The BFR KMR guidelines describe, among other matters, compilation of existing information, identification of gaps and traceable documentation. Their direct scope concerns federal projects. For another project, these principles provide technical guidance; the official and contractual requirements actually applicable must also be clarified.

Working approach

How FONTANA-EOD works

Document the agreed specialist service clearly

We assess the planned groundworks against the available documents and their design revision. Before attending site, we agree with you what needs to be investigated, which areas are accessible and what findings are required. If the design or site conditions change, we check whether the agreed scope remains appropriate. The report states what was actually investigated and the limits of the findings. This allows designers and site management to see which findings they can use and where questions remain.

Discuss the investigation task

The task before the equipment

We first establish the investigation objective: which question must it answer? We then select a technically suitable method. The availability of a particular device or experience on a similar neighbouring site is not enough to justify the choice of method on its own.

Keep limitations visible

Inaccessible areas and limited findings are identified. They are shown separately in the report and overview plan. Planners and site management can then decide specifically which areas still need work and when a suitable investigation will become possible.

Clarify changes before intervening in the ground

A new location, additional depth or different construction methods are compared with the existing results. Changes are passed on with dates and clear plan references. Feedback is provided before the affected work so that an unresolved question can be incorporated into the workflow.

Hand over the report and plan together

The technical conclusion remains connected to its location references and appendices. A brief summary helps orientation but does not replace the documented survey scope. This basis is retained even if site management or contractors change.

Understand the results

Use technical statements for the next decision

Read results together with their scope

A finding is understandable only together with its investigation task. Consider the area and depth described, methods used and limitations. A report title or single results line alone is insufficient. For new work, these details are compared with the current plan. This allows a technically justified distinction between findings that can be reused and questions still outstanding. The documented areas and depths remain decisive even if the property or project name stays the same.

Understand investigation reports and their limitations

Use project terminology unambiguously

Document review, surveying, construction-phase specialist work and recovery are different tasks. An enquiry need not identify the correct method in advance. An accurate description of the intervention and required decision is more useful. This establishes the appropriate technical scope and prevents a general term from meaning different things in design, procurement and execution.

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 preparing a construction project in Garbsen

Does every project have a building application conference?

The city describes this service for larger construction projects. Whether a conference is useful and which participants are needed should be clarified with the city’s building advice service for the specific project.

Does the geoportal show whether explosive ordnance assessment is needed?

The city’s explanation identifies spatial planning information, including development plans. Such a map extract is not an explosive ordnance finding. Specialist assessment needs the existing findings and the ground works actually proposed.

Who handles a connection trench outside the property?

Clarify with the planners and utility provider who will arrange the required investigation and which coordination with the authorities is needed. Mark the trench’s location and depth on the plan. A report for the building area does not automatically cover a connection trench outside it.

Are meeting minutes clearance documentation?

No. They initially document the discussion and recorded tasks or decisions. An investigation result needs its own technical evidence and limitations. Official requirements must be identifiable as such and must not be inferred from your own summary of a discussion.

Which details does FONTANA-EOD need for the initial discussion?

A current site plan with ground works areas and depths, existing explosive ordnance records and questions from earlier project coordination are helpful. Add proposed utility connections and temporary areas. We can then assess which information is missing and which investigations are needed.

Who should bring together the investigation reports from the different parties?

Identify a responsible person in the project organisation for the shared set of documents. The respective clients and specialist contractors remain responsible for their agreed tasks. A central overview makes handover easier but replaces neither complete technical reports nor necessary decisions by the responsible bodies.

What should I do if I find a possible item of ordnance?

If possible explosive ordnance is found, stop the affected work immediately. Leave the object untouched, keep your distance and warn others without putting yourself at risk. In Germany, notify the police immediately on 110 and follow their instructions. Do not investigate, move or transport the object yourself.

What determines the work involved in a coordinated investigation?

Alongside areas, depths and methods, the available records, access and timing dependencies are decisive. Describe which sections can be covered together and which are accessible separately. Comparable quotations need the same prerequisites and a clearly identified handover of results.

Project enquiry

Enquire about a construction project in Garbsen

Send all proposed ground works areas

Send a site plan with the building, utility connections, working areas and temporary ground works. Add the respective depths and existing analyses and investigation reports. Mark areas whose plans may still change and identify the earliest proposed earthworks.

Assign tasks and contacts

Tell us which parties plan and commission individual areas or connections. Known handover points, responsibilities for missing records and a date for the technical findings needed are helpful. Outstanding questions can then be coordinated specifically before quotation and programme planning.

Add the project address, land parcels, current project status and planned construction dates. Official conditions are provided with their complete appendices. Identify the decision needed and relevant date, together with existing utility and as-built plans.

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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