- 1st February 2021
- Posted by: Dom Senior
- Category: Projects
Location: Coventry Client: Coventry and Warwickshire University Hospital
We were commissioned to undertake a Flood Risk Assessment to support the Planning Application and discharge of planning conditions for a proposed new car park located in the functional floodplain at Coventry and Warwickshire University Hospital in Coventry.
The proposal will provide an additional 1600 new car parking spaces to the hospital staff north of the confluence between the Withy Brook and the River Sowe.
- The site is situated within Flood Zone 3 and Flood Zone 2
- The site is at low to medium risk of surface water flooding
- The site was considered to be at a high risk of groundwater flooding
Detailed hydraulic modelling was undertaken to clearly assess flood mechanisms within the car park and ensure the proposal does not exacerbate flood risk elsewhere. Throughout consultation with the Coventry and Warwickshire University Hospital Trust, Coventry City Council and the Environment Agency, we also developed a flood response plan involving cutting edge telemetry, tailored to the flood risk classification of the site.
Like conventional flood response plans, flood emergency procedures on site were broken down into four phases.
1. Preparedness, focusing on steps taken before an event
The production of the flood response plan is a preparedness action in itself. Identifying risks and specifying actions to reduce these. The plan provides a step by step guide of how to respond to a flood event.
To optimise flood evacuation procedures, the car park has been split into three zones. Blue, Red and Green with clear signage to mark each zone. This can then be used to evacuate each zone one by one (phased), allowing higher risk areas to evacuate first and prevent overwhelming infrastructure from a mass evacuation.
b. Evacuation Routes
A clear evacuation route has been provided to show the safest route out of the hospital onto the main roads, where cars will head to the designated emergency overflow car parks. This will also prevent confusion, ensuring the hospital infrastructure is not overwhelmed. A clear route avoiding evacuation traffic has also been considered to allow emergency services to access the site without getting caught in the evacuation traffic.
In order to ensure users of the car park are aware of the risk it was recommended that signage be installed within the car park highlighting this risk. This also includes the coloured zones and the installation of depth marker boards to assist site managers in decision making.
d. Crash Barriers
In order to limit the spread and damage of vehicles that may be mobilised by fluvial action, crash barriers were designed to limit the mobility of vehicles under fluvial conditions.
2. An early warning and trigger system
a. Flood alert and Met Office Severe Weather Warning system
The site manager is to register to receive flood alerts from the Environment Agency and Severe Weather Warnings from the Met Office. These will alert the site manager to predicted heavy precipitation events.
b. Warning system
On-site telemetry systems are to be installed on the Withy Brook and the River Sowe. These will monitor the water levels in real time allowing the site manager to monitor river levels 24 hours a day. These are also set to trigger a warning when river levels reach ‘flood’ threshold levels.
c. Visual inspection
These systems are supplemented by visual inspection. This involves inspecting the High Bridge water levels of the Withy Brook, water levels in the River Sowe and the marker boards in the car park. This overcomes the risk of technological failure to ensure key staff are not taken away from vulnerable patients during a flood event unless absolutely necessary.
Messages are to be sent to a list of those using the car park. This ensures only those who use Car Park 11 will receive the warning preventing a mass panic across the hospital. The messages will be disseminated via the business standard communication methods, such as the bleep system, emails and text messages.
3. The Response
This is the result of the trigger or warning systems, the actions that are required to be taken by the site manager and those who use the car park.
This is to be a dry off-site evacuation. An evacuation undertaken in dry conditions prior to flooding when access and egress to the site is maintained. This will be informed by the warning system, in place and disseminated to the affected staff. Staff are to be evacuated in a phased approach based on the zones and follow the evacuation route off site to an emergency car park determined by the site manager.
This is a wet on-site containment of the site undertaken during flooding that occurs within the car park OR when access/egress is compromised. This is unlikely to occur due to the number of triggers in place to alert the site manager to a flood event. However, in the event where flooding occurs on-site and it is not safe to evacuate as outlined by the flood response plan, the barriers will be lowered and the car park closed. Staff will be alerted to the procedure and told not to return to their vehicles or enter the car park until informed it is safe to do so.
c. Returning to the site
Site staff are to conduct damage assessment and advise on the future use of the car park. The insurance company should be contacted and liaison with the emergency services and local authority should be undertaken prior to re-opening the car park. Any staff undertaking the clean-up activity should be provided with appropriate PPE. The car park should not be opened to wider staff until the car park has been deemed as safe.
4.Adaptation and improvement
As part of any new staff induction, it is recommended that staff review the flood response plan to ensure awareness across the hospital. In order to attain a permit to park in car park 11 staff will have to review the flood response plan to ensure all users of the car park are familiar with the plan and how to respond during a flood event.
b. Emergency drills
In order to maintain awareness and ensure all staff are aware of the procedures an annual drill should be undertaken to run through the stages of flood event and planned procedures.
c. Live document
It is imperative that this flood response plan is not seen as a document to overcome planning permission. It should be continually reviewed and updated with any procedural changes or after each flood event to review what went well and what could be improved. This ensures the longevity and improvement of the plan.
Whilst the granting of Planning Permission will significantly reduce car parking capacity issues at the hospital, the cutting edge telemetry system on site and flood response plan we developed in collaboration with the trust will ensure that hospital staff and their belongings do not get exposed to flood events occurring in the future within the facility.