Flood Response Plan West Oxford / New Botley Area
FLOOD WARNINGS Oxford Area Flood Partnership
Environment Agency – Floodline Warnings Direct
By phone Register to receive free Flood Warnings by phone, email or fax to landline or mobile numbers for your home and other places. Information for residents, owners and other stakeholders Register online https://www.fws.environment-agency.gov.uk/app/olr/register
Flood Response Plan
Flood warning The three levels of warning are: West Oxford / New Botley Area Severe Flood Flood Alert Flood Warning Warning Guide No.1 of a series - for Oxford flood risk areas
Summary
Flooding in West Oxford generally develops slowly, giving time to respond.
The Environment Agency (EA) will give the public at least two hours’ notice of Flooding is possible. Flooding is expected. Severe flooding. Be prepared Immediate action required any local main river overtopping its bank (flood alert) or flooding properties Danger to life (flood warning). By monitoring escalating situations, flood response organisa- tions will normally be ready least one day ahead.
Once alerted, City Council staff check critical river levels several times a day
in order to track the rate of rise and decide whether and when to deploy tem- porary defences. LATEST INFORMATION during a flood Environment Agency Variations in timing, rate, location and total amount of rainfall make each flood Call ‘Floodline’ (24 hrs) on 0345 988 1188 to hear up-to- date local flood different. So, while guided by experience of previous floods, OAFP partners warning and river level information or speak to an operator. liaise closely in order to focus on making best use of available resources and The type talk number for this service is 0845 602 6340. enable response to be based on the developing situation. We aim to imple- ment as much as possible during daylight hours. ‘Live maps’ (updated every 15 mins) https://flood-warning-information.service.gov.uk/warnings Under flood response conditions, the Oxford Area Flood Partners increase the number of staff on standby and monitor flooding in all critical areas. They stay Others in frequent contact with other organisations working in the area, including the Emergency Services. Listen to Radio Oxford Follow the Oxford Mail Flood blog As floods develop, incident coordination centres and local communication cen- Council web pages change to improve links during emergencies: tres are set up which liaise with regional and national centres. This enables a Oxfordshire County Council http://www.oxfordshire.gov.uk comprehensive and rapid response as appropriate to each situation as it Oxford City Council http://www.oxford.gov.uk evolves.
Version: Aug 2014 1. (See back page for details of ‘Floodline Warnings Direct’)
Response arrangements IS YOUR PROPERTY AT RISK OF FLOODING?
EA “Flood Alerts” and ‘Flood Warnings’ prompt City Council staff to monitor Flood Risk maps river levels frequently. The EA internet pages. The EA internet pages show https://flood-warning-information.service.gov.uk/long-term-flood-risk the developing situation for many of the main rivers in Oxford.
Once water is over the banks of Bullstake Stream, staff will frequently check 3 day Flood Risk Forecast the rate of progress of the flood across the allotments behind Bullstake Close https://flood-warning-information.service.gov.uk/5-day-flood-risk to decide whether and when to deploy Bullstake Close defences2 (including a mobile 6” pump). The demountable plank wall is installed first. The access Environment Agency flood information https://www.gov.uk/browse/environment-countryside/flooding-extreme-weather track to the allotments is left open as long as possible for use by allotment
holders, before closing with sandbags and plastic sheeting.
Meanwhile (subject to availability) the EA deploys a mobile 6” pump to Duke
St.
If water levels rise at Bullstake Close, the access track to the allotments will PLAN HOW TO DEFEND YOUR PROPERTY be closed. The pump will then be used to return the water that passes the defences back to the flood plain. Once Bullstake Close defences are in place, the City Council will maintain 24- For advice on household flood defence hour cover, with a “Bronze” command3 stationed there. Staff will then monitor National Flood Forum flood levels in the area more often. http://nationalfloodforum.org.uk/ Association of British Insurers – As water levels approach Duke St along the footpath from Bulstake Stream, https://www.abi.org.uk/products-and-issues/topics-and-issues/flooding/ the City Council will build a defence from sandbags and plastic sheet across 4 the path (progressively if necessary) up to the level of the adjacent doorstep. LEARN FROM OTHERS Once water reaches the level of the lowest road gully covers in Earl St and Duke St (provided a further rise is expected) the City Council will close the isolation valves5 on the surface water sewers. Your local flood action group 6 Earl St will then be drained by the pumping station below the pavement. Oxford Flood Alliance http://www.oxfordfloodalliance.org.uk/
———————————-
2. Bullstake Close is the lowest point of the Botley Road connected to the flood plain upstream, so is the first part of the area to be defended. 3. Bronze’ Command is an on-the-spot manager. Bronze / Silver and Gold Com- mands are a hierarchy of temporary communication centres set up in emergencies to control activities over areas of increasing size. REPORT PROBLEMS during a flood 4. For Duke St footpath, a permanent base is proposed for a demountable defence, Oxford City Council 01865 249811 (switchboard) which would be quicker to install and remove than the sandbag wall which has been (or use the report form on the website) used to date. (The proposed Western Conveyance might make this unnecessary.) www.oxford.gov.uk (put ‘Flood’ in search box) 5. The isolation valves in Earl St and Duke St prevent backflow into the low-level gullies when the level in Bulstake Stream prevents flow out from the surface water sewers in Botley Road HOW TO USE SANDBAGS EFFECTIVELY
7 Duke St will continue to be drained by the temporary pump.
Sandbags At Osney Court the managers will deploy temporary WCs and walkways Sandbags can’t stop water: They can only slow it down. A plastic sheet larg- when necessary. The boundary walls help to protect the Botley Road.
er than the area being covered will be needed to work with the sandbag to As floods rise further at Bullstake Close, the City Council will install make an effective flood barrier. ‘Floodstop’ 8 water-filled units across the entrance to the Bullstake A single sandbag in a bin bag, stamped against an airbrick, would be more Close car park and use smaller pumps to return leakage from there to effective at saving your home from flood than a heap of sandbags. And a the floodplain north of Bullstake Close . few, close-packed against sheet of plastic, can protect a doorway. If water rises yet further at Bullstake Close, there is a risk that the defenc- Moving fewer bags might save your back too! es there would retain water on the flood plain to a level that could enter
Sandbags are good for stopping waves from passing traffic, washing Botley Road houses which would not otherwise be affected. The City into your garden or against your house, but will not hold back standing Council will liaise with the EA to determine the appropriate time for pro- water. gressive removal of the sandbag defence to allow flood water across Bot- ley Rd, as occurred in 2007 when there were no defences here.) So if your house is at risk, purpose-made barriers (with airbrick protec- tion if appropriate) and a pump would be a worthwhile investment. ‘Floodstop’ barriers would be installed on the Earl St road hump9 to
improve protection there before water was let onto Botley Rd.
The Environment Agency provides advice on using plastic with sandbags, and In order to guide flood flows to Lamarsh Road the ‘Floodstop’ barrier at how to lay sandbags if more than one layer is needed: Bullstake Close would be extended across the inbound lane to the https://www.gov.uk/government/publications/sandbags-how-to-use-them-to-prepare-for-a- crown of Botley Road. This still enables emergency vehicles access flood along Botley Road and leaves open a route to Lamarsh Road for any The City Council will establish a temporary distribution point for sandbags on Botley flood flows emerging from Osney Court.
Road, the location of which may vary dependent on the areas at risk, and the areas available to set up. Previous locations have included: ———————————- PC World It may also deposit pallets of sandbags at other locations 6. The flood pumping station in Earl St drains the last two road gullies at the south end. However, when the isolation valve is closed, an underground over- flow enables it to drain all gullies in the road. This allows optimum use of the OXFORD AREA FLOOD PARTNERSHIP capacity of the two pumps before the road actually floods. This should help take groundwater flows that leave houses through their airbricks. Oxford Area Flood Partnership (OAFP) formed after the 2003 floods, to help 7. In Duke St, the EA temporary pump sucks from a chamber with direct connec- local organisations better co-ordinate their flood management activities. tion to the surface water sewer. With the isolation valve closed, this makes best The partners are: use of the pump’s capacity if the road floods, and will help take groundwater that Oxford City Council The Environment Agency escapes from houses through airbricks in a smaller flood. Oxfordshire County Council Thames Water Utilities 8. Floodstop barriers are a line of re-usable proprietary plastic units filled with wa- ter that are quicker to deploy than an equivalent sandbag defence. Vale of White Horse District Council Network Rail 9. The Earl St road hump was installed as a result of lessons learned from the OAFP works closely with interested groups in the community. 2007 flood, and is set at a level just higher than the road crest in Lamarsh Road. To ensure that water flows to Lamarsh Road, temporary barriers will be installed Details can be found on the Oxford City Council website. across the Earl St hump and across the footways each side. www.oxford.gov.uk (search:flood)
Lamarsh Road is now available as a flood route (as it once was). FIRE & RESCUE SERVICE Its role in flooding During floods, water ponds to kerb height at the low point on Lamarsh Road
just off Botley Road. This matches the level on the floodplain to which it drains. However, the improved road drains will now help to remove any flood water crossing Botley Road, until flows exceed the drain capacity. The Fire & Rescue Service assisted in the floods of February 2014, by helping to keep the Botley Road open with its pumps and ensuring that the Once that occurs, the build-up will escape along the service road because Abingdon Road could be opened much sooner than otherwise possible. the road level has been lowered at the entrance to the Dunelm / Halfords car park. With the road hump and barriers at Earl St, Lamarsh Road now Despite having no statutory responsibility for responding to flooding, provides a managed route for flood water. Oxfordshire County Council’s Fire & Rescue Service (OFRS) is trained and equipped to undertake water rescue and pumping activities during floods to Larger road gullies and an improved highway drain and outfall ensure that provide an appropriate emergency response across the county. However, Lamarsh Road will drain faster than it did after the floods in 2007. flooding can impact in different ways on different occasions and this may re-
The Lamarsh Road flood route will be made more effective by pumping over sult in the Service having to respond to different priorities as a flooding event the crest towards the southern flood plain if a suitable pump is available. progresses. Therefore, there can be no guarantee that the Service will be able to respond in exactly the same way and with the same results as previ- ously.
With this in mind, OFRS is keen to support multi-agency prevention work and community resilience activities, as well as helping to co-ordinate and re- spond to areas that are in danger of flooding, in order to help mitigate the risks TYPES OF FLOODING and minimise the impact of the floods on residents and businesses.
Surface Water Flooding
Surface water flooding (flash flooding) can occur anywhere during heavy rain- In Feb 2014, OFRS provided ‘hose barriers’ and pumps at 3 critical points fall, giving little time to respond.
Maps on the Environment Agency website show areas at risk.
https://flood-warning-information.service.gov.uk/long-term-flood-risk
Surface water flooding can also occur when rainfall exceeds the capacity of highway drainage systems or surface water sewers, or these have become blocked.
Blocked drains should be reported for investigation to … Oxfordshire County Council 0845 310 11 11 or https://www.oxfordshirefloodtoolkit.com/emergency/report-flood/
TYPES OF FLOODING (continued) ‘Live river levels’ can be checked on the EA website
https://flood-warning-information.service.gov.uk/river-and-sea-levels
River (fluvial) Flooding This shows water levels upstream and downstream of most locks. River flooding happens when the channel of a river or stream cannot cope with This is a typical display. the volume of water from upstream, typically when heavy rain falls on ground that is already waterlogged. Where possible, the river then spreads across its natural floodplain, which in some parts affects urban areas including houses, The graphic display updates roads and businesses. every 15 minutes.
Maps on the GOV.UK website show areas at risk ... The river level reading is https://www.gov.uk/check-if-youre-at-risk-of-flooding updated daily: Click here to see levels up- (More often during floods). stream of lock
Groundwater Flooding In Oxford, river floods drive groundwater through flood-plain gravels, when it can come up under floors or affect low-lying areas. Although called ‘groundwater flooding’, the effects are temporary and recognised locally as an Environment Agency issue, linked to river flooding.
Elsewhere in the UK, true groundwater flooding can persist for months when driven by large underground water reserves. It is then an issue for Lead Local Flood Authorities.
For some houses, internal property flooding from rising groundwater can be a greater threat than flooding by water from outside. In the early stages of a flood it can help to leave airbricks open as an outlet for rising groundwater.
It’s best to close airbricks with watertight covers as late as possible and re- open them at the earliest opportunity to aid ventilation. Automatic airbricks could help, as they act as one-way valves.
Sewer Flooding Many of Oxford’s foul sewers are connected to rainwater systems and can overflow during heavy rainfall in the absence of river flooding. However, during river floods, higher groundwater levels infiltrate the network and cause sewage overflows and loss of use of WCs.
You should report problems to Thames Water on 0800 316 800 or https://www.thameswater.co.uk/help-and-advice/drains-and-sewers/sewer-flooding- who-to-contact It helps if each affected household reports problems, to help Thames Water establish the extent of the problem.
Bullstake Close: Temporary barrier and sandbag wall
Bullstake Close:
Temporary barriers
Botley Rd: Temporary barrier
Lamarsh Rd: Large highway drain
Earl St: Flood pumping station
Lamarsh Rd: Temporary pump
Lamarsh Rd:
Flood route (blue arrows) will come into use in moderate / Re produced from the Ordnance Survey map with the significant events, taking pe rmission of the Controller of Her Majesty's Station- ery Office (HMSO). Crown Copyright. Unauthorised water from Botley Road to rep roduction infringes Crown Copyright the downstream floodplain.