This timeline sets out the key events from before plans for Ripon's new swimming pool and leisure centre refurbishment were approved, to the present day.

Concerns about ground stability on the Camp Close site were highlighted before Harrogate Borough Council's planning committee approved the council's own planning application on 25 June 2019.

• February 2018:  A sinkhole opens up on the leisure centre car park


• June 2019: The planning application for new swimming pool and leisure centre refurbishment is approved


• June 2019: Local press reports that some councillors at the planning meeting had expressed ‘deep concerns’ about Camp Close site and hadn't supported the application


• June 2019: Dr Alan Thompson sends email to HBC principal planning officer Gill Ritchie claiming that when the application was approved, ground stability issues were ignored and the council ignored its own planning policy


• November 2019 principal contractor Willmott Dixon (WD) starts on site, after being awarded a £10.2million contract for delivery of the scheme over 17 months


• September 2020 WD discovers a 'void' while digging foundations at the entrance of the leisure centre


• September 2020 construction and property consultancy Stantec inspects the void and meets on site with WD and property infrastructure and construction company Pick Everard to discuss possible mitigation measures


• October 2020: Stantec produces a detailed cavity inspection report for WD and HBC, which raises concerns about the load-bearing capacity of piles under the existing leisure centre and flags up wider ground stability issues affecting the site


• October 2020: The report says that the 'void' discovered by WD should, in the short term, be backfilled with gravel, regularly monitored and topped up


• The Stantec report states: "The risk of the ground collapse further impacting on the existing building can’t be overlooked" and "further detailed investigations are required to evaluate the stability of the existing building"


• November 2020: HBC issues press release saying that the project had been ‘slightly delayed’


• May 2021: HBC cabinet approves additional spending of £110,000 for investigation of the void


• May 2021: Michael Constantine, the council's head of culture, tourism and sport, answers questions from councillors and gives assurances about the site


• June 2021: A Freedom of Information request is submitted to HBC for the engineering reports on the Camp Close site, by chartered civil engineer and local campaigner Stanley Mackintosh


• July 2021: Mr Mackintosh receives a redacted copy of the Stantec report from HBC and supplies it to Dr Thompson


• July 2021: Dr Thompson sends letter by email to all HBC cabinet members, with his observations on the report and raises new concerns from a geological perspective.