Senior civil servants at the transport ministry’s roads department pushed through a permit to dump half a million tonnes of granite waste into an artificial lake in Gelderland, even though the officials in charge of taking the decision had rejected it, according to television current affairs show Zembla.

Zembla bases its claim on whistleblower statements, and internal emails and other documents. The programme, to be broadcast on Thursday night, says two civil servants rejected the application to dump the waste, a bi-product from the roads industry, but that they were overruled by senior officials.

The waste, a clay-like substance left over when granite and sand are crushed and prepared for road building, comes from Amsterdam company Graniet Import Benelux in Amsterdam, which is part of stone import group Bontrup BV.

Bontrup bosses and the senior civil servants were introduced by former foreign minister Halbe Zijlstra who has worked for construction company Volker Wessels since his resignation for lying.

He told Zembla that a solution had to be found for the waste product because so much was being stored at the Bontrup site, future road building supplies were at risk.

Soil

Chemists and other experts told Zembla the waste had been wrongly classified as ‘soil’ to facilitate the dumping and that any toxic substances could leach into the water.

‘You should certainly not dump this material into an uncontrolled system as a lake,’ environmental chemist Joop Harmsen told the programme. ‘You have no idea what the impact in the future could be.’

Transport ministry officials said in a statement that granite waste can be dumped if it meets official conditions, ‘which this did’. ‘Retrospectively, the process of granting the permit could have been done better,’ the statement said.

The lake at Over de Maas was created when sand and gravel was extracted for the construction industry and has already been the subject of dumping scandals – most recently involving waste from Belgium. The area is now being redeveloped into a nature reserve.