Review, test and revise your reservoir flood plan

There are three ways in which you can keep your flood plan effective:

  • Review to make sure the flood plan is complete and up to date
  • Test to make sure the flood plan is understood and works in practice
  • Revise to amend the flood plan if there are major changes at your reservoir, or in the people or processes used to manage it.

Your supervising engineer will also want to review your flood plan and they may make recommendations for improvements in their section 12 statement.

Review your reservoir flood plan

You should amend your flood plan after any change at the reservoir or in your operational procedures. It is best to do as soon as the changes occur. Keep a schedule of the changes so you can provide this to your supervising engineer to allow an easy review.

You should review your flood plan at the following intervals:

  • every 12 months, usually to coincide with a visit by your supervising engineer
  • after any test or partial test of the flood plan
  • on appointment of a supervising engineer
  • on appointment of an inspecting engineer
  • following any change in the water level prescribed by an engineer
  • at any time recommended by your engineer or by us

A review should be sufficient to check that minor changes have been incorporated satisfactorily. Minor changes should not alter your general approach to an incident and should be limited to providing new information to help your response. Some examples of what we consider to be minor changes are:

  • changes to names and telephone numbers
  • changes to access arrangements (such as padlock numbers)
  • updates to the location and site plans
  • changes to your communication plan

Major changes should prompt a full revision, see the guidance below.

After each review, update the cover page of your flood plan with the date of your review.

Test your reservoir flood plan

Prepare a schedule of testing for your flood plan

You should create a schedule of testing for your flood plan to make sure it works and to help the right people become familiar with it. Discuss your proposed testing schedule with your supervising or inspecting engineer.

Keep your test schedule as part of your overall reservoir safety management plan. We recommend the test schedule is kept separate from the flood plan itself to avoid the flood plan document becoming too large.

You should decide on the manner and frequency of testing by considering the complexity of your reservoir and the number of people you would expect to be involved during an incident.

If you manage a high-risk reservoir, or there are more complex structures or procedures, or you have multiple operational staff, you will need to develop a system to test all reasonably foreseeable incidents, even if they have a low likelihood.

Your inspection reports should contain the inspecting engineer’s view as to the potential failure modes for your reservoir. You should develop test scenarios around these.

If your reservoir is smaller with simple infrastructure, and / or you have very few people looking after it, you should still test your flood plan to avoid complacency.

Your test schedule should set out:

  • the element of the flood plan to be tested
  • the manner of testing
  • the interval between tests

For example:

Emergency draw down

Open scour valve and allow water to run until clear (as recommended in inspection report) every six months.

If your engineers specify any testing, you are expected to complete this within the timeframe they provide. A successful test will

  • confirm the details are correct and that all equipment works as expected
  • identify potential problems and encourage improvement
  • record learning points that can be shared with new staff later
  • provide staff with a greater level of understanding and confidence

Desk-based and physical testing

Some parts of your flood plan can be tested as a desk-based exercise, such as checking phone numbers and checking contractor or materials availability. Other parts will need a physical test, such as opening valves.

Remember to record valve testing in Part 16 of your prescribed form of record.

How to test your reservoir flood plan

Test inflow and outlet controls

You should fully open the bottom outlet (scour valve) and other drawdown equipment when recommended by your inspecting or supervising engineer, or every 6 months if no recommendation is given.

You should open valves completely against full reservoir head until the water runs clear and is steady flowing. This prevents silt or debris from being trapped in the system. In-situ and mobile drawdown facilities should be operated.

Before releasing water from a reservoir, you must obtain water discharge Environmental Permit. Statutory water undertakers may also use consent under section 166 of the Water Industry Act 1991 You must complete a risk assessment and warn us of any testing which may cause an environmental impact.

You should discuss with your supervising engineer if a valve test may be valid if the valves are fully opened in sequence without releasing water.

Test people

Your test should include any staff you would expect to be involved in a real incident.

This will help them become familiar with the flood plan and identify training needs.

Check how well decisions are made. Test any actions where you have delegated specific authority.

Where your flood plan includes the use of contractors or consultants, you should test their availability and their ability to supply materials, personnel or advice.

Test equipment

Check and test the equipment that you’d expect to use during an incident.

Remember to include any equipment you may own but which is kept away from the reservoir.

Test communications

You should test communications at the site. This will normally consist of landline telephones and mobile phone signal, but could include satellite phones, radios, Wi-Fi, fax machines, alarms and sirens.

Full test incident exercise

If your reservoir is designated as a high-risk reservoir, you should programme a full incident simulation exercise at least once every 10 years to test all elements of your flood plan. You should also carry out a full test within 1 year of any major revision of your flood plan.

The purpose is to test all aspects of responding to an incident which are within your control. A full test is a valuable learning exercise in how to deal with incidents and should involve all operational staff and your supervising engineer.

A full test does not need to include the emergency services. However, if you manage a high-risk reservoir which holds the potential for flooding a large population or critical infrastructure, your local emergency planner may contact you to understand your reservoir better or to arrange an exercise of its response plan, known as an “offsite plan”.

If your organisation is also an emergency responder, you should consult with your emergency planner on how to combine a test of your onsite and offsite plan.

If your reservoir is not designated as a high-risk reservoir, we recommend you still test your flood plan periodically and take advice from a reservoir engineer on technical matters.

Partial testing

You may be able to justify testing just part of your flood plan, for example, operating the scour valve on a regular basis. If you carry out partial tests at different times, make sure each test is recorded and that all elements of the flood plan are tested over time.

Keep test records

You should keep a clear record of each test you complete. To keep your flood plan concise, your schedule and the results of the tests, should be kept separately or as a part of your normal operating procedures.

If you have a high-risk reservoir, you must record information on testing valves, gates, and penstocks in Part 4 of your Prescribed Form of Record.

If your testing reveals problems or opportunities for improvement, keep a record of the lessons learned, and make the necessary changes to your flood plan. Large scale tests with several people should be followed by a debrief and summary report.

You can notify us about any lessons learned so we can help other reservoir owners where appropriate. We share lessons learned anonymously unless you give us permission otherwise.

Testing schedules for multiple reservoirs

If you manage more than one reservoir you should prepare a schedule of testing which accounts for the similarities and differences between each reservoir, their location and the people that operate them.

Where your staff or operating procedures are substantially different between sites, you should maintain a schedule for each reservoir, as for a single reservoir.

If your operational procedures are broadly similar across the reservoirs, you may benefit by creating a single schedule of testing, but you should be able to demonstrate how:

  • the tests are carried out
  • site-specific issues are addressed
  • learning points are transferred between sites

You may find it beneficial to identify cluster groups for testing.

As a general guide we recommend the following frequency for your test schedule:

  • 2 to 15 reservoirs – a full test at one or more reservoir at least once in every 10 years
  • 16 or more reservoirs – a full test at one or more reservoir at least once every 5 years

You should review and amend your testing frequency to reflect significant personnel changes, so new staff are familiarised with your flood plan.

Your supervising engineer may make recommendations as to the scope and frequency of testing, and you are expected to complete this within the timeframe given.

Revise your flood plan

Major changes at your reservoir or in your operational procedures should prompt you to carry out a full revision of your flood plan. A major change is one where your response requires a substantially different approach. Examples of major changes include:

  • changes to the principal dam structures, for example, a replacement scour valve or installation of a siphon
  • company re-organisation changing levels of authority, responsibility or reporting lines
  • a test reveals errors or shortcomings in your flood plan
  • revision of trigger levels or pre-determined response actions

Add your revisions to your schedule of changes. After each review, you should update the cover page of your flood plan with the date of your revision.

Read our guidance on how to Prepare a reservoir flood plan


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