Explosive war remnants, investigate in suspect area

What is it?

If the digital map shows that a location where you intend to dig is suspicious for the presence of unexploded remnants of war, you, as the client, are obliged under the Occupational Health and Safety Act to carry out further research before digging into the soil/ having it excavated.

The study that must be conducted for this purpose is called a "Project-Related Risk Analysis (PRA). This is mandatory. During the investigation, the risks of expected explosive remnants of war are assessed in relation to the (civil engineering) work to be carried out. If unacceptable risks occur, an advice on the necessary measures follows.

The law has no requirements for the quality of a PRA. You can prepare a PRA yourself or have it done by a certified agency. However, for approaching and clearing explosives, it is always mandatory to use a certified agency and inform the municipality.

As the client, you can also decide not to prepare a PRA. In that case, you must hire a consulting firm to supervise the work on site with detection equipment. This is often a more expensive procedure.

How does it work?

Preparing a Project Related Risk Analysis (PRA) involves investigating whether the soil in which you plan to dig has already been disturbed after WW ll. You will need at least:

  • Overview of planned excavations (horizontal and vertical|);
  • Historical research: what was the situation in 1945 and what is today (what has changed);
  • Understanding the effects and sensitivities of the potentially explosive remnants of war;

Under additional information, you can read the full structure of a PRA.

You can request a copy of the 1945 aerial photograph and data from the Basic Records from the municipality for historical research purposes. There is a charge for this.

What does it cost?

Research costs are at your own expense.

Additional information

Note: Project-specific risk analysis (PRA).

By default, the PRA consists of the following components:

  1. Establishing the scope of work;
  2. Analysis of the historical preliminary investigation conducted;
  3. Establish site-specific conditions and vertical delineation;
  4. Identification of civil engineering work and factors affecting explosive remnants of war;
  5. Analysis of hazard and identification of elaboration factors;
  6. Assessment of risks and recommendations to mitigate unacceptable risks.

Because an area-wide historical preliminary investigation has already been commissioned by the municipality, it is known what types of explosive remnants of war may be present and in what soil layer they are expected to be present.

This fleshes out work steps 1 through 3.

Next, the risks associated with the execution of the proposed work should be assessed. To this end, an inventory is made of the (civil engineering) work being carried out within the suspected area (step 4).

The inventoried operations and the effect they may have on residual explosive remnants of war are described.

Revelant actions are (not exhaustive):

  • Installation of piles / sheet piling;
  • Excavation of (water) soil;
  • Raising;
  • Sampling as part of environmental health, soil mechanics or archaeological soil research;
  • Groundwater abstraction;
  • Demolition activities including the removal of piles/pile walls. Influence factors are inventoried and evaluated for each operation. Among others, the following factors of influence are distinguished:
  • Motion;
  • Vibrations/accelerations in the (water) soil;
  • Touching an explosive remnant of war;
  • Outdoor exposure.

For step 5, hazard factors of the anticipated explosive war residues (and detonators used) are inventoried and described. Examples include: prestressed firing pin spring, susceptibility of explosives or pyrotechnic or incendiary charges. Also considered are any special risks posed by explosive war residues, e.g., shaped charge, white phosphorus and toxicity.

This assessment may lead to the following conclusions in Step 6:

  • There is no increased risk in relation to the work to be carried out. This conclusion can be drawn if the work takes place outside the suspected soil layers or the work has no effect on the possibly present explosive remnants of war. In that case, no project plan needs to be prepared and no detection study needs to be conducted.
  • There is an increased risk. In this case, additional measures must be taken to ensure safety. Additional measures involve detecting and removing any explosive remnants of war prior to the start of work or supervising the groundwork by a certified detection company. This company will first prepare a project plan for this purpose.

Draw up project plan

Before commencing detection, the initiator shall have a project plan drawn up by the certified detection company, which will carry out the actual detection. This plan describes the mutual relationship between the parties involved, the planned progress, agreements, supervision, documentation and procedures to be able to carry out the work adequately and safely.

Conducting detection research

Detection includes determining the presence of (possible) explosive remnants of war by taking measurements, using detection equipment, and evaluating the measurement data. Based on the search objective, the site-specific circumstances and the applicability of the various detection methods, a certified detection company must develop a customized approach for the explosive remnants of war soil survey for each site.

Local regulations

Fees Regulation