When employees may come into contact with contaminated soil and or groundwater, they should have received instruction on the measures to be taken. As a supervisor, the DLP or DLP-R training is mandatory for this. For other employees, there is the OPM training. This explains to employees what measures should be taken at what time and, above all, what risks and hazards they may face. OPM training is actually the most ‘forgotten’ training. Despite the legal requirement, many companies lack the knowledge that this training should be offered to employees. The guidelines of the DLP, DLP-R and OPM training courses can be found in the CROW 400.