Guidance

Reservoir panel engineers responsibilities: on-site emergency flood plans

Updated 25 June 2021

It is a legal requirement for all undertakers to prepare an on-site emergency flood plan for all large raised reservoirs in England.

There are legal duties for engineers relating to these flood plans.

1. Who needs to comply

The legal responsibilities apply to:

• supervising engineers
• a qualified civil engineer from either the All Reservoirs Panel of Engineers, the Supervising Engineer Panel, the Service Reservoirs Panel or the Non-impounding Reservoirs Panel for reservoirs that are not high-risk
• construction engineers for reservoirs under construction

2. Responsibilities

Undertakers must consult engineers in preparing a flood plan. As an engineer, you must certify that the flood plan meets the direction’s requirements and send the certificate to the undertaker and email a copy to the reservoir safety team at the Environment Agency.

Read the direction.

Undertakers must take an engineer’s direction in how to test and revise the plan.

You should:

• help undertakers to prepare flood plans
• advise the undertaker how and when to test the plan
• help the undertaker to keep the flood plan under review and, where necessary, direct the undertaker to revise the flood plan
• review the flood plans if there are plans to decommission, alter or enlarge a reservoir

3. Prepare a flood plan

You should advise the undertaker about the information needed in a flood plan, including:

• a plan of actions undertakers must take to prevent, control or mitigate an uncontrolled release of water
• procedures to follow to respond to an emergency
• areas at risk of flooding

3.1 Areas at risk of flooding

Undertakers must include the areas that may flood if there was an uncontrolled escape of water from the reservoir in the flood plan.

Engineers should check this information is in the flood plan and how it informs the actions included to prevent, control, or mitigate an uncontrolled flood from the reservoir.

The Environment Agency has published guidance on how to assess the consequence of dam break or reservoir failure. The Environment Agency published flood risk maps in 2010 for most large raised reservoirs. Updated versions should be available from Spring 2021. Where available, undertakers should include these flood risk maps in the flood plan.

If flood risk maps are not available, the undertaker should use other sources of information to identify risk areas, such as:

• Lidar
• Ordnance Survey maps
• satellite imagery
• historical incidents

4. Issue certificates and directions

You need to certify that the flood plan meets the legal requirements in the direction. You should then send the certificate to the undertaker and a copy to the Environment Agency. Certificates for flood plans are valid for 5 years.

You may need to issue a new flood plan certificate if:

• the reservoir has a new undertaker
• there is a significant change to the flood plan
• the areas at risk of flooding change (for example, if there are new buildings downstream)
• a reservoir is modified and returns to a construction phase

Certificates and directions should follow the format set out in Schedule 4 and Schedule 6 of the Reservoir Act 1975 (Capacity, Registration, Prescribed Forms, etc.) (England) Regulations 2013.

5. Testing and revising a flood plan

It is a legal requirement for undertakers to keep their flood plans under review.

Undertakers should review the plans every year and revise them if necessary to ensure the information remains current. Appointed engineers can also direct undertakers to revise the flood plan.

Undertakers must test the flood plan following the directions of the appointed engineer.

5.1 Testing schedule

You will direct the undertaker on how and when to test the flood plan.

We suggest that undertakers review and test the plan alongside the supervising engineer’s annual Section 12 assessment of the reservoir.

Undertakers will be committing an offence if they do not test their plans following the engineer’s direction. The Environment Agency will monitor compliance.

Testing the flood plan should be proportionate to the reservoir’s type, size and flood risk impact level. Exercises can be a desk-based run-through up to a full-scale exercise, including involving category 1 emergency responders. Testing should be proportionate to the reservoir’s risk of flooding and is likely to differ between high-risk reservoirs and not high-risk reservoirs.

High-risk reservoirs

Test the plan as a desk-based run-through with a site walkover

You should encourage the undertaker to annually:

• review the plan to confirm that the details are correct and that all equipment and relevant operational and technical elements of the reservoir referenced in the plan are functional and work as expected
• do an on-site, or desk-based run-through of the plan to ensure that the undertaker, all relevant staff, and the supervising engineer understand their incident response roles

Test the plan with a full incident simulation exercise

When you recommend testing a plan with a full incident simulation exercise, you should encourage the undertaker to be proportionate and collaborative.

A full incident simulation exercise ensures that people involved in an emergency response know what to do and manage a response in cooperation with category 1 emergency responders.

A full simulation exercise should happen more frequently if a reservoir poses a significant risk to a large community (high impact probability) or where an undertaker has responsibility for several reservoirs.

Examples of how often to test a plan

If the undertaker owns up to 15 high-risk reservoirs and the reservoirs have a likely low impact, undertakers should perform a full incident simulation exercise at a minimum of one of their reservoirs at least once every 10 years.

The exercise should involve the appointed engineer and include operational staff from the other reservoir sites, those in cascade, and all emergency responders to participate or observe.

If the undertaker owns 16 or more reservoirs, or an individual reservoir has a high impact probability, undertakers should perform a full incident simulation exercise at a minimum of one of the reservoirs at least once every 5 years.

The exercise should involve the appointed engineer and include operational staff from the other reservoir sites, those in cascade, and all emergency responders to participate or observe.

An exercise should involve personnel in the organisation with a role in responding to a major reservoir incident and should include as a minimum:

• deployment of staff as per the plan requirements
• contacting equipment and materials suppliers to confirm their availability during an emergency
  operation of valves and drawdown facilities

Not high-risk reservoirs

Undertakers for any not high-risk reservoir should carry out a desk-based review and run-through and a site walkover every year. Undertakers should complete an incident simulation exercise at least every 10 years in consultation with an appointed engineer.

With the appointed engineer’s support, the undertaker should share the exercises’ lessons across all reservoirs in the group. You should encourage undertakers to also share across the industry, including with other undertakers.

5.2 Revising the flood plan

The section 12 annual written statement by a supervising engineer should:

• confirm that the plan has been reviewed
• report how the flood plan has been tested or exercised, including the routine testing of valves
• include any recommendations to the undertaker on the revisions needed to the plan

When carrying out a section 10 inspection, the inspecting engineer should consider the flood plan, confirm it is fit for purpose, and, if necessary, make any recommendations for revision. This could include changes needed due to required measures in the interests of safety (MIOS). For example, the flood plan may need additional steps while MIOS works are being planned and carried out, stopping after the MIOS is completed and certified.

6. Reservoirs that are under construction

Construction engineers cannot issue a preliminary certificate for a reservoir under construction until a flood plan is in place.

If there is already a preliminary certificate, the undertaker must have a flood plan within 12 months of being notified about the direction.

The construction engineer should advise the undertaker to keep the flood plan under review and test it at least annually until a final certificate is issued.

Measures to prevent, control and mitigate flooding may change as construction progresses and the reservoir performance is monitored. The plan must therefore be regularly reviewed and revised to reflect this. The construction engineer should get advice from the Environment Agency about the areas at risk of flooding if there is no flood risk map for the reservoir.