Vereniging voor Explosieven Opsporing

Centrale belangenbehartiger voor opsporen Conventionele Explosieven!

Preliminary investigation

The process is divided into two primary phases in the WSCS-OCE, namely:

  • preliminary investigation
  • UXO detection

The aim of the preliminary investigation is to assess whether there are indications that CE is present within the investigation area and, if so, to define the suspect area.

If there is a reasonable suspicion during planned (building) works that CE will be encountered in the bottom of surface waters or ground a Preliminary Investigation must be conducted prior to works commencing. The client is responsible for this (construction process provisions in the Working Conditions Decree, HSE in the preparatory phase). For further background information please see our Position paper on compulsory certification and sub-areas WSCS-OCE.

The SZW Inspectorate (Ministry of Social Affairs and Employment Inspectorate) actively monitors this and takes enforcement action if necessary. In paragraph 9.4 of its Civil and Hydraulic Engineering Sector Report 2014 the Inspectorate states the following with regard to this:

  • Inspectors shall take firm action if an investigation into the presence of explosives has not been conducted or has not been conducted adequately. The work shall be stopped due to the direct danger for employees and bystanders. Clients (often local authorities and water boards) are obliged to ensure that the correct investigations are conducted during the design phase in order to prevent risks arising during the construction phase.
  • The preliminary investigation must meet the process requirements contained in the WSCS–OCE. By complying with these requirements the client establishes the basis for the proper and detailed mapping of suspect areas. Certified detection firms may only start the detection and approach work once the suspect areas have been properly mapped.
  • A sector guideline (BRL-OCE) was in force up to 1 July 2012. Investigations conducted in accordance with this guideline are no longer current and are incomplete. Inspectors have encountered serious situations whereby work has been undertaken in “areas free from explosives” and in which CE was still encountered. In those cases, the cause lay in an incomplete preliminary investigation, the contractor’s lack of expertise and the pressure exerted by the client to ensure the progress of work.

The specific requirements are described in paragraph 6.5 of the WSCS-OCE. The preliminary investigation is broken down into the following main elements:

  • inventory of source material;
  • assessing and evaluating the source material;
  • reporting and CE likelihood map.

The WSCS-OCE describes the (minimum) sources that must be consulted during the preliminary investigation and the way in which the assessment of the source materials has to be undertaken. This describes the ‘minimum investigation effort' for the preliminary investigation.
In addition, specific requirements are set for the output of the preliminary investigation; a report and a CE likelihood map.
Paragraph 6.5 and Annex 3 of the WSCS-OCE also contain specific provisions about the way in which the suspect area has to be defined.
With regard to the former BRL-OCE guidelines the requirements set for the preliminary investigation in 2012 have changed substantially. Click here for further information about the reasons for this and the most important changes.