The latest drainage proposal submitted by Taylor Wimpey for Thames Farm has been objected to by South Oxfordshire District Council Drainage Section and also OCC the Lead Local Flood Authority for the area.
The proposal was to pump the surface water from the site on the Reading Road along a piped system underneath the road towards Henley, then it will turn off down land adjacent to Sheephouse Farm (near the new Bremont HQ) and out onto a watercourse next to the sports pitches at Jubilee Park next to Tesco.
SODC and OCC commissioned their own report from McCloy Consulting (Water & Environment Consultants) who reported that there were missing evidence and calculations in the Enzygo report commissioned by Taylor Wimpey for overland flows which will enter the proposed site and how this will be managed. There was also no modelling in the previous report by Enzygo for pump failure or an increase in magnitude or frequency of rainfalls nor the effects of the proposed grouting works to the run-off calculations undertaken and in relation to flood risks of the watercourse. The report also states that the proposal does not meet the South Oxfordshire Local Plan 2035 Sustainable Drainage Systems (SuDS) – the need to manage surface water as close to the source as possible, mimicking surface water flows arising from a site prior to the proposed development. It does not currently demonstrate adequately to the satisfaction of the LLFA (Lead Local Flood Authority) that surface water (pluvial) flood risk has been properly considered.
Thames Water have objected to the proposal too. They say, “Whilst Thames Water agree with the approach of draining surface water runoff to nearby watercourses, we are unable to support the discharge of condition 11 at present. We require confirmation that a deed of agreement has been reached with the riparian owner of the watercourse at the point of discharge. We also require confirmation that the LLFA are in agreement with the drainage strategy in relation to the impact of the watercourse downstream of the proposed discharge point.”
Taylor Wimpey originally planned to drain the surface water through soakaways in the site but in early 2019 they discovered the chalk bedrock was prone to developing sink holes and suffered from major underground dissolution features and so this wasn’t feasible. They now are proposing to fill the ground with grouting to stabilise it which could cause problems to the nearby drinking water supply as the aquifers serving the bore hole runs immediately beneath the site.
Emma Bowerman, Principal Major Applications Officer at SODC replied to Peter Boros of the Thames Farm Action Group (TFAG) saying, “In terms of the question of whether the additional information that Taylor Wimpey has submitted has altered our view on the groundworks requiring separate planning permission I have no further update for you on this. I still need to consider the information they have submitted and take advice from others. As soon as I have an update I will let you know. So our position on this remains as before, that in terms of the information we have considered, we are of a view that the groundworks are a separate engineering operation that requires planning permission. So to clarify, P20/S2808/DIS considers the drainage strategy, which in our opinion is unacceptable. And the question about whether the groundworks require planning permission falls outside of the scope of P20/S2808/DIS. Although I completely appreciate that there are crossovers and I would not have been comfortable approving drainage details without first resolving the issues surrounding the groundworks.”
Peter Boros from TFAG commented, “We are delighted that the various bodies consulted and responsible for drainage in the area have at last recognised the voracity of what we have been saying for the last year, and have taken independent advice to verify this. We remain of the opinion that with ground conditions as problematic as Thames Farm has, it is not the right place to try and build 95 new houses. The scheme needs to be revisited and replanned so that a conventional SuDS based solution can be employed as with the vast majority of development sites in the area. We recognise that Taylor Wimpey may only have discovered the problems with the ground after they purchased it, but to continue trying to develop an unsuitable site in an unsuitable way makes no sense at all. They must recognise that they made a mistake in buying this site and now look at things in a pragmatic way without causing annoyance and angst to a whole lot of people who live in the area and would suffer the consequences of the increase in flooding and the huge scale of engineering operation that this site would require in order to effectively create a concrete mass 16m deep on which they might build their houses.”