The second week of the Inquiry was devoted to hearing the submissions of the first Statutory Objector to the scheme, the Oxford Preservation Trust. Their arguments focused on two major points. Firstly they claimed that the Environment Agency had been slow to realise the ecological importance of Hinksey Meadow and in consequence the impact of the scheme had not been studied in sufficient detail. The second claim was that the option of having no channel in the meadow, and therefore leaving the site untouched, had not been fully examined. OPT accept that conveyance of flood water has to pass through the meadow but want the channel removed.

The OPT’s fielded three expert witnesses, on hydrogeology, fluvial hydrology, and ecology. Ms Fraser’s evidence on hydrology cast doubt on the reliability of the EA’s understanding about how the gravel aquifers in the area work. Her evidence was extremely technical, and focused on interrogating the methodology used by the Environment Agency to model the way that water moves across the scheme. In her expert opinion, there remained uncertainty as to how the surface water and groundwater interact, including which direction the groundwater actually flows through the site. 

Additionally, the calibration of the model used by the EA resulted in scenarios that do not match the “real world” movement of water in the area (although she also explained in cross-examination that all models are different to reality to some extent, by the very nature of their being models). This led her to conclude that groundwater in the area could be lowered by the scheme at certain times of the year. The consequences of this, in her opinion, were that there was no evidence to conclude the mitigation sites would be suitable for MG4 grassland. As for mitigation, it was premature to start to consider mitigation while the hydrogeology of the site was still unclear.

In cross-examination, Ms Fraser clarified that her analysis was based purely on the impact of the scheme on the water levels on the OPT meadow, rather than at a regional level, and that she had not been asked to analyse what the impact on groundwater would be if there were a submerged twin pipe scheme going through the meadow.

The EA fielded three members of their team, covering modelling, ecology and scheme design, to rebut arguments advanced by the OPT. The EA argued that they were aware of the importance of the meadow in 2014 when it was decided to develop the scheme. The first botanical studies were undertaken in 2015. The EA accepted that the model used to assess impacts on groundwater at Hinksey Meadow has limitations – it was designed for a different purpose. They also accepted that some data had been entered incorrectly. Ground water in the meadow will be monitored going forward and mitigation for any change in the levels can be adjusted as required. The EA has had boreholes in the meadow since 2018 and now has sufficient data to be able to establish a robust baseline for tracking any future changes to groundwater levels. A more refined model would not fundamentally affect the need to route the channel along the side of the meadow. 

The EA also argued that they have reviewed the ‘no channel in the meadow’ option but conclude it would increase flood risk and make the performance of the scheme unpredictable. They do not see any viable way of mitigating these effects. This was the only alternative put forward by OPT to the scheme as designed.

The OPT and EA agreed a statement of common ground on a number of planning issues which OPT had intended to raise. The inquiry adjourned early at 2pm on Thursday and will recommence Tuesday 28 November.