Comments on City Council plans for Osney Mead

Oxford City Council has issued a draft Supplementary Planning Document for the development of the western end of the city centre, an area which includes Osney Mead. The council is inviting comment. The relevant documents can be found here:

Osney Mead floods and will continue to do so even after the Oxford Flood Alleviation Scheme is built. How flood risk will be managed as plans come forward will need very close scrutiny. OFA believes the SPD should be strengthened in a number of areas to set an appropriate framework for managing potential future flood risk, including from sewers. We also believe the approach to biodiversity needs strengthening in line with the approaches adopted by the Oxford Flood Alleviation Scheme. OFA has submitted the following comments to the City Council:

a) Flooding and flood risk – the documents acknowledge that Osney Mead floods and will continue to do so after the completion of the Oxford Flood Alleviation Scheme, and that any development there needs to create capacity to contain and manage flood water. This can only be done, the documents say, if the whole Osney Mead site is developed in a joined-up way. The documents also recommend the creation of the appropriate infrastructure before any other development. We strongly support this view. Management of flood risk needs to be taken very seriously in any plans which come forward, not just for Osney Mead itself but also for adjoining areas. There is a risk that piecemeal re-development of the site could increase flooding locally and it would be challenging to monitor and manage.

While we welcome the general statements made about flood risk we do not see how some of the descriptions and images of proposed redevelopment on Osney Mead are consistent with flooding of the area. We therefore have serious questions about how well flood risk has been understood by the authors of these documents. In particular, the documents talk about ‘activating’ the riverbank south of Osney Lock and down to Grandpont. The proposals envisage a new, wider cycle and pedestrian route along here, river-facing buildings (apartments, offices) and new spaces for people to sit. The illustrations of what this might look like show a heavily urbanised and landscaped river frontage with paths and building all at the same level. But the towpath floods most years and is often impassable. This is flood zone 3b, part of the natural flood plain, and the types of development permitted in such an area by the National Planning Policy Framework are very restricted.

How can the envisaged ‘activated’ frontage as illustrated in these documents possibly be realised in these circumstances? Will the bank be raised to create the kind of structures shown in the SPD? If so what happens to flood water which currently overtops the Thames banks and inundates adjacent areas? Canalising the Thames at this point would create significant flood risk for existing communities both up and downstream of the area. Or will the riverside path remain at existing levels and be allowed to flood? This is very unclear in the documents. We would like to see explicit statements in the SPD and design guidelines about the challenge of ‘activating’ the riverbank given that it is in flood zone 3b. Illustrations in the documents should also present a more realistic view of what the redevelopment might look like.

The design guidelines talk about new bridges connecting the towpath by the Punter to Barret St on the other side of the Thames, and one at the eastern end of South St crossing the Osney Stream to connect to Osney Mead. In both of these locations temporary flood barriers are currently deployed when river levels are high. These barriers are critical to preventing houses on Osney Island from flooding. At the end of South St there is a large wall where the proposed new bridge would come across. This wall helps to contain flood water in Osney Stream. The demountable flood defences for the island  are stored in the EA’s Osney depot. If this depot is to close and move we need to understand how flood defences will be deployed during a flood emergency. A large pump located on EA land behind the houses on the eastern end of South St is also a critical part of the local flood defence system. This pump evacuates flood water from the island and pumps it into the weir pool. Even after the completion of OFAS houses on Osney will continue to be vulnerable to flooding and temporary defences will still be required. We would like to see the SPD/design guidelines explicitly state that any developments must not compromise flood defences for Osney Island.

A holistic approach to redeveloping Osney Mead potentially creates an opportunity to help reduce flood risk to Osney Island as well as addressing the challenges of the Osney Mead site itself. We would like to see the SPD flag up this opportunity as something to be explored. We have a rare opportunity to reduce risk for vulnerable Osney residents and this should not be missed.

Redevelopment of the Castle Mill area could potentially affect streams and weirs in that section of the city. Any plans coming forward should ensure there is no reduction in the capacity of these streams to help move flood water through the city. Could the performance of these water courses be improved to help alleviate flood risk in the city? Has this been considered?

b) Sewers – the current sewer system on Osney Mead does not cope with floods and is quickly infiltrated by flood water. Sewage is pumped from Osney Mead up Bridge St on Osney Island to join the main sewer on Botley Rd. In a flood the pressure in the system means sewage bubbles out of the sewer covers and has to be pumped into the river. Some people on Osney Island cannot use their toilets during a flood. We raised this issue in a previous consultation but there is no mention of sewer infrastructure in the Supplementary Planning Document or the Design Guidelines issued for consultation.

We need assurances that adequate sewer infrastructure will be put in place and this must be a prerequisite for any redevelopment of Osney Mead. The increased density of proposed redevelopment will greatly increase pressure on the sewer system. Failure to address this infrastructure requirement could be disastrous for some Osney residents and would mean regular discharges of sewage into the local wate ways to the detriment of the wildlife. When we have tried to raise these issues with Thames Water in the past they simply say ‘it’s caused by fluvial flooding which is nothing to do with us’. We know what an appalling track record the water companies have on river pollution. A holistic approach to the redevelopment of Osney Mead must include addressing the sewerage problems, including using flood mitigation measures to reduce risk of sewers being infiltrated.

c) Biodiversity – throughout the development of the Oxford Flood Alleviation Scheme we have been strong supporters of the ‘environmental vision’ of the scheme and the idea of making the new stream as natural as possible. This helps reduce long-term maintenance of the assets being created and is far more sustainable than a more engineered approach. We believe a similar approach should be adopted for Osney Mead. The design document talks about ‘sensitivity to habitat’ and of retaining ‘existing trees where possible, especially those of good ecological and amenity value.’ A glance at Google Earth shows the two main areas of tree cover on Osney Mead are along the bank of Osney Stream opposite the houses in Bridge Street extension, and along the towpath south of Osney Lock down to the railway bridge. The SPD seems to envisage the elimination of all of these trees. This is a major contradiction in the documents. Removing them would take out most of the existing habitat. There is a considerable difference between the carefully thought through strategies in OFAS for how biodiversity will be enhanced through the project, and the vague reliance on street trees and green roofs in the SPD design document. Green roofs need regular maintenance including irrigation and addition of fertiliser. There are some positive words in the design guideline but protecting and enhancing existing biodiversity in the area, including incorporating wild, unmanaged space into the design, hasn’t been adequately thought through. Continuing to allow the river frontage to operate as natural floodplain as it does currently, with the trees and other wild vegetation retained, would be less environmentally destructive and cheaper to maintain. We would like to see approaches here better aligned with OFAS’s approach to enhancing biodiversity. The SPD should include explicit references to OFAS and its environmental vision, and alignment with this should be a requirement of any developments coming forward. The OFAS project covers an area which borders Osney Mead and includes important targets for new wild flower meadows in the area. Opening access into the greenbelt from Osney Mead must not compromise the biodiversity targets OFAS is committed to delivering.

Flood compensation for new Oxpens development

The proposed redevelopment of the Oxpens area involves the lowering of some land to compensate for the raising of other areas to lift them out of the flood plain. The initial round of consultation in the summer attracted a fair amount of comment on the need to preserve floodplain capacity as this helps reduce risk of property flooding.

A new set of consultation documents has just been issued and OFA is pleased to note that flood compensation has been calculated on what is known as a ‘level for level’ basis. In other words any land which is raised will be compensated for by lowering land within the same height band elsewhere on the site. We understand the Environment Agency insisted on this.

One of our major concerns with the Seacourt Park & Ride extension was that compensation was not calculated on this basis resulting in a loss of floodplain capacity. The Environment Agency allowed this at the time despite our protests. We’re please that for this new development the appropriate industry recommended approach has been adopted. The compensation includes an additional allowance for climate change and should help with reducing flood risk in the city if the development goes ahead.

Sewer flooding in Campbell Road

Residents in Campbell Rd, Florence Park, had their gardens flooded by sewage on 21 October in a near repeat of a similar event last year. This time round Larkrise Primary School had to be shut for a day.

Overflowing sewers are a long standing problem in the area.  Earlier this year OFA supported local residents in organising a meeting of relevant agencies, chaired by MP Annaliese Dodds, to discuss solutions. This followed a serious incident on 3 and 4 October 2020 when gardens were flooded with sewage to a depth of 60cm. Some sheds and home offices were affected, causing misery for people working from home because of Covid.

The meeting, which involved Thames Water, the City Council and the Environment Agency, was constructive, but progress since has been slow. A report which Thames Water should have completed on the causes of the 2020 floods has still, it appears, not been provided to the Council. The clean-up response to the events a few weeks ago again showed the company apparently unable to deal with the community other than on a customer by customer basis.

OFA is supporting the community in trying to get a number of short term measures adopted to ease the situation while a wider solution is worked out. The sewage released in these events spills into Boundary Brook which enters the Thames downstream of Donnington Bridge, adding to the levels of pollution in the river.

Flood risk increasing says Environment Agency

‘Significant climate impacts are inevitable especially for flood and coastal risks, water management, freshwater wildlife and industrial regulation,’ says the latest Environment Agency adaptation report published earlier this month.

According to the latest projections, summer rainfall in the UK is expected to increase 22% by 2080, and winter rainfall by 13%. The report sets out what the agency is doing to help reduce flooding of properties and businesses, ensure future drinking water supply, reduce pollution, and protect the biodiversity of freshwater habitats. The  Oxford Flood Alleviation Scheme (OFAS) features as a case study in the report, an illustration of the kind of action the EA is taking in partnership with others.

Early action is needed the agency warns: ‘Despite more than a decade of concerted effort to reduce these risks, the speed and scale of climate change means that many are either increasing or remain significant. This broad conclusion matches recent assessments from the Climate Change Committee, the Intergovernmental Panel on Climate Change and others.’

The OFAS scheme will be submitted for planning approval this winter. The planning documents will incorporate the latest government assumptions about future rainfall and flood risk.

High river levels test flood preparedness

In the first week of February we’ve experienced the worst flooding in Oxford since 2014. The coordinated response from the Environment Agency and local authorities shows how far we’ve come in recent years in the management of flood events. We owe them a big thank you.

Back in the early 2000s flood management was reactive and often disorganised. But lessons were learned and we now benefit from much better levels of preparedness, and good cooperation between the various agencies. We also benefit from the infrastructure put in place to divert water away from houses, and from regular clearing of water courses of fallen trees and flood debris.

Bulstake Close barrier and pump

The high level of flooding this year has provided a robust test of flood management procedures. With UK winters getting wetter and wetter we can expect more of these type of events and bigger ones, so it’s important we continue to refine the response to make it as good as we can get it. This is something OFA is actively working on. The flood alleviation scheme is still some years away.

A major weak spot currently is the slow response of Thames Water to residents experiencing sewage leaks. We have had reports of sewers in various locations overflowing as a result of the high flood water. Householders reporting these problems have found Thames Water difficult to engage. OFA is raising these issues with the various bodies responsible for flood management. Oxfordshire MP Robert Courts has insisted Thames Water ‘must do more’ according to a BBC report. We agree.

Flooding from sewer South Hinksey

We also think communication to local residents during a flood event about what’s happening and what’s being done in response could be improved. These events are also an opportunity to educate residents, particularly new residents, about the nature of the flood risk in their area. OFA has initiated discussions about this with the Environment Agency and other interested parties.

At a local level the response in some specific communities can be further refined to ensure the most vulnerable households are known about, and receive timely and targeted help. The new barrier in South Hinksey had its first serious test. It did the job required of it but will need some further adjustments if it’s to be effective in a larger flood. The Environment Agency is looking at this.

We continue to be concerned about safety issues at the Seacourt Park and Ride extension once it is open. We believe there is a significant risk of cars being stranded in flood water there. The Seacourt Stream overflowed into part of the existing car park during the recent foods, leaving parked cars standing in shallow water. The bike rack by the bus stop was also flooded.

Cars standing in flood water at Seacourt P&R

Adrian Porter, from the OFA Steering Group, was interviewed on BBC Oxford on 5 February about the flooding across Oxford and about our ongoing campaigns.

Seacourt car park safety concerns

One important area of concern for us during the planning process for the Seacourt park & ride extension was the safety of users of the car park. The speed with which the site flooded on Christmas Eve underlines the risk here. In the planning application the Council argued that: ‘Historically, river levels have risen fairly slowly in this location even during extreme events, giving sufficient warning for mitigation measures to be put in place.’ But the recent flood did not conform to this pattern.

Are the Council’s safety measures at the car park robust enough? We doubt it. Had the park and ride extension been operating there would probably have been several cars bobbing about down there. Flood barriers were only erected by the City Council at Bulstake Close after the flooding had already happened.

At the peak of the flooding river levels were so high water from the Seacourt stream west of the existing car park started to encroach onto the parking area (see photo below). There were several cars parked there. Had river levels been higher these cars would have been stranded. Flood management plans for the park and ride need to be reviewed.

Seacourt car park extension flooding

The recent flooding of the extension to Seacourt Park & Ride is further evidence that the City Council seriously underestimated the vulnerability of the site to flooding. The area flooded rapidly during the night of Christmas Eve, and as of today is still partly inundated though water is now being pumped out.

View of the extension down the main access ramp on Christmas Day

The Flood Risk Assessment (FRA) submitted with the Planning Application stated: ‘An analysis of historic flooding incidents relevant to the site suggests that the site will currently flood roughly once in every 1.7 years and will remain out of operation for around 10 days during an average flood event.’ That’s just under 6 days a year average.

Over the course of last winter (2019/20) the site was inundated four times and for prolonged periods. This latest incident represents a further 12 days of flooding. In our opposition to the planning application we argued that the Council had grossly underestimated the likely extent of flooding at the site. Events seem to be proving us right.

Sewer flooding in South Hinksey

It is not uncommon for residents of Kennington, North Hinksey and South Hinksey to suffer from sewer flooding problems and these continued over the Christmas period with surcharges occurring on both the 24th and 27th December. Both dates coincided with the heavy rainfall events and result from Littlemore Pumping Station being unable to cope with the high volume of water.

The second surcharge was particularly challenging for South Hinksey residents as the EA flood barrier prevented the sewage from leaving the village. Thankfully the pumps the EA had already provided prevented houses from being flooded, but they couldn’t stop a pollution incident as the sewage discharged into the local water courses.

Several residents reported the incident to Thames Water, but their response time was well short of their two-hour target. We know of one call which was responded to eleven hours after being reported, and another which took a whole three days. We’d be interested in other readers’ experiences.

OFA Steering Group member Adrian Porter has once again raised the poor level of service with the Thames Water customer liaison team.

Christmas 2020 flooding

Residents in Wolvercote, West Oxford, North and South Hinksey and Grandpont witnessed significant localised flooding on Christmas day after a rapid rise in river levels over the preceding days. Between the 17 and 22 December, more than 25mm of rain fell across the upper parts of the Thames catchment resulting in high river levels on the Thames and the three main tributaries feeding the Thames – the Evenlode, Windrush and Cherwell. An additional 20-60mm of rainfall fell between the 22 December and the 24 December on the already saturated Upper Thames catchment causing a rapid rise in river levels on the Thames in Oxford. The large volume of water discharging from the Cherwell to the west of Christchurch Meadows, is thought to have caused flood water further upstream in Oxford to back up, contributing to a faster rise in levels than we typically experience in the city.

After peaking on Christmas day levels fell, but further rainfall on Saturday night nudged levels back up. The rivers seem to have stabilised since and levels are expected to fall in the coming days. The peak level of the recent flooding was significantly higher than those seen during last winter’s flood events. The Environment Agency has been actively monitoring the situation and flood barriers were erected in South Hinksey as a precaution. Flood Warnings were issued for Wolvercote, and for the New Botley – North/South Hinksey – Grandpont areas. There have been no reports of properties in the city flooding.

The speed at which river levels rose on Christmas eve is particularly concerning, as this limited the amount of time available to deploy defenses. This has potential implications for future flood management planning.