Published on 11 May 2017
Response to criticism of report on damage investigation
Study in Emmen
In 2016, Witteveen+Bos conducted an investigation of structural damage to properties in and around Emmen to determine whether this damage could be attributed to mining and gas abstraction activities in the region. Numerous complaints of serious cracks, subsidence and other problems had been received from homeowners following a sustained earth tremor (measuring 2.3 on the Richter Scale) which occurred on 30 September 2015. Individual investigation reports were submitted to property owners on 15 June 2016. A general, collated report was also published.
The Technical Committee on Ground Movement (TCBB) is an independent body established to advise on the adverse effects of mining and gas abstraction activities. Witteveen+Bos was informed (through a third party) of the TCBB’s initial reaction to the Emmen investigation. We issued a full and detailed response and decided to include a link to the TCBB’s report on our website, once it had been given formal status.
On 30 March 2017, a meeting was held to discuss the TCBB report and our response. It was attended by representatives of the TCBB, the National Coordinator for Groningen (NCG), the gas and oil company NAM, the Municipality of Emmen, the Ministry of Economic Affairs, the Housing Safety Centre (CVW) and Witteveen+Bos. The meeting considered both the Emmen investigation and that conducted in Groningen region. We were able to conclude that the TCBB now accepted that much of its original criticism of the investigations was unfounded. The TCBB was expected to produce a full report of the meeting by way of rectification.
Study in Groningen
Between August 2016 and March 2017, Witteveen+Bos conducted an investigation of structural damage in the Groningen region. A total of 2,077 properties were inspected, accounting for 33,877 individual defects alleged to be attributable to mining or gas abstraction activities. As in Emmen, Witteveen+Bos conducted this survey in a systematic, scientifically responsible and extremely thorough manner. We provided full transparency with regard to the process and methodology. Independent experts, other engineering consultancies, the TCBB and (representatives of) residents’ groups were all invited to ‘look over our shoulders’. Any recommendations for improvement were implemented wherever possible and appropriate. The study went even further than its predecessor in Emmen in that an advisory panel of independent experts was appointed, and an additional geotechnical survey was conducted to confirm certain findings. This was one the TCBB’s recommendations following the Emmen study. We were happy to comply, although it seemed unlikely that the additional survey would produce results markedly different from those of other investigation methods.
Always open to comment
In any investigation or study there will be certain aspects which, perhaps with the benefit of hindsight, could have been done differently or better. This is certainly true of particularly complex issues such as whether there is any link between structural damage and earth tremors, and how those earth tremors were caused. Witteveen+Bos is confident that the findings of its investigations in both Emmen and Groningen are accurate and will stand up to any scrutiny. That said, we are always open to comment regarding our approach, and are willing to meet with stakeholders to discuss any misgivings they may have.