Following retirement, Grundy used his reputation and technical knowledge to assist with and to disseminate information about disaster mitigation and relief in developing countries. This initiative was prompted by the disastrous Indian Ocean earthquake and tsunami of 26 December 2004 after which he helped form the 'Joint Working Commission for Disaster Reduction on Coasts' at the IABSE Conference New Delhi in February 2005, to develop and implement a Guide for Disaster Reduction on the Coasts of the Indian Ocean, now expanded to encompass disasters globally.