Busting a few myths about OFAS

Here’s a fact check on some of the more exotic claims being made about the proposed Oxford Flood Alleviation Scheme. Many of these issues have been around for some time – but misinformation continues to circulate about them.

Myth 1: The two-stage channel provides very little benefit and the scheme would work without it

The key document to look at on the County Council Planning Portal is ES App Q Modelling Review of No Channel. This compares modelling data for the scheme as designed with options of having no two- stage channel at all or no channel in Hinksey Meadow. The report goes on to discuss the impact of having no channel on the performance of various elements of the scheme, and likely consequences.

With the channel all but 367 houses and 151 businesses are protected against a one in a hundred year flood event. With no channel at all 524 houses and 210 businesses would be unprotected. That means an additional 157 houses and 59 businesses would be at risk of flooding in a one in one hundred- year event. Over and above this, protective earth bunds and walls, a key part of the scheme, would need to be higher and longer, and in some places this would not be achievable putting properties and infrastructure at risk.

App Q also says:

In addition, the freeboard below bridge soffits would also need to be increased to meet the agreed consenting requirements for this scheme. This would make the raised bridges more visually intrusive in the landscape and increase the length of approach ramps to bridges which then creates additional restrictions across the floodplain.

Removing the two-stage channel just in Hinksey Meadow obviously has a less severe impact on the effectiveness of the scheme. The modelling for this option shows 438 houses unprotected (an increase of 71 compared to the scheme as designed) and 172 businesses (21 more).

The scheme is not just about individual homes and businesses but also roads, cycle routes, utilities, other infrastructure, disruption to city life. The channel provides a defined route for the additional floodwater to pass through the western floodplain – it brings certainty and reliability. Without the channel floodwaters are dispersed, increasing flood risk in some areas. When all factors are weighed up the scheme as designed offers the best option according to the review.

Myth 2: The ‘Hinskey Meadows’ will be ‘destroyed’

Hinksey Meadow, north of Willow Walk near North Hinksey (owned by Oxford Preservation Trust) is home to rare grassland. Most of the rest of the scheme area is agricultural land with relatively poor biodiversity. The scheme proposes taking up to 1.3ha of Hinksey Meadow for the two-stage channel, the rest of the meadow (11.7ha) will be preserved, and considerable attention has been given to ensuring the hydrology in the area is not affected by the scheme.

In the rest of the scheme area 17.8 ha of additional flower rich meadows will be created. This will obviously not have the diversity of Hinksey Meadow but over the life of the scheme these meadows will increase significantly in complexity. Wetland areas will also be created along the course of the new stream, and the whole scheme area will be actively managed for biodiversity. None of this will happen if we maintain the status quo.

Myth 3: Maintenance has only been budgeted for 15 years

All costs, including maintenance for 100 years, are costed and form part of the overall economic analysis, and specific funding sources have been identified for the first 10 years. No construction project is required to specify exactly where maintenance costs will be met from fifty or a hundred years from now. That’s impossible. Any alternative proposal would face the same issue. 

Myth 4: Construction means 114 HGV vehicle movements a day on and off the A34 for 3-5 years

Construction of the channel is expected to take 3 years. Movement of soil from the site will take place mainly in a 15 month period spread over two summers. The EA is proposing to bring forward a separate planning application to use rail to move a significant amounts of material which will substantially reduce road use.

Myth 5: Construction will result in a big increase in carbon emissions

The ES Non-technical summary for the scheme says:

The whole life carbon dioxide emissions over the project life are estimated at 19,558 tonnes and the operational carbon is 4.65% of this (i.e. 909 tonnes) based on the proposed maintenance regime. To put this into context, a 2019 Oxford City Council report stated that carbon dioxide emissions from the city in 2017-2018 were 718,362 tonnes per year. The emissions due to the Scheme including operation for 100 years would be equivalent to the direct emissions from the city for less than 10 days.

The planning documents referred to above can be found here: https://myeplanning.oxfordshire.gov.uk/Planning/Display/MW.0027/22#undefined Look under ‘Documents’ and use the search bar to locate the document you are looking for. A full description of all design options considered for the scheme is set out in the Environmental Statement, section 2.3.