Carry out a risk assessment for a bespoke permit to deposit waste for recovery

You will need to carry out a risk assessment for a bespoke permit application.

You must prevent or minimise emissions from your recovery activity if your risk assessment suggests that your site will have an impact on:

• local residents, properties or designated habitat sites
• groundwater or surface water

You should follow the general guidance on how to carry out risk assessments for your environmental permit (GOV.UK). You must also carry out a water risk assessment. Your risk assessment may also need to include information about:

• engineering work
• risk of gas
• aftercare monitoring
  
  

Water risk assessment

You must use a tiered approach to do your hydrogeological risk assessment. This means that the greater the risk of pollution, the more detailed assessment you carry out.

You will need to carry out a qualitative risk assessment. This may lead to a quantitative risk assessment if your waste recovery activity is in a sensitive location.

If your conceptual site model shows that the waste you propose to use is unlikely to be a hazard to groundwater or surface water, then you do not need to carry out a quantitative groundwater risk assessment.

If your risk assessment suggests that your activity will have an impact on groundwater or surface water, you must install an attenuation layer. You must use suitable material with an appropriate thickness and permeability to prevent pollution.

If you need to carry out engineering work

Where your risk assessment shows that you need to carry out engineering works, you must include in your application information where you need to:

• do engineering work to protect the environment from your activity – for example install an attenuation layer
• monitor the environment – for example by installing monitoring boreholes

 Find out about engineering construction proposals for deposit for recovery.

If risk of gas is identified

Where your risk assessment suggests there is a risk of gas and you plan to deposit waste more than 2 metres below the surrounding ground surface, you must monitor your waste for:

• methane
• carbon dioxide
• oxygen

You must install the appropriate number of monitoring boreholes per hectare as indicated by your risk assessment. The boreholes must extend to the full depth of the waste.

You can rely on searcher bar (also called spike test) monitoring where the total depth of the waste is less than 4 metres, or before the deposit is complete. You must record the atmospheric pressure when you take gas readings.

If you detect 1.5% v/v (volume per volume) methane in your waste monitoring boreholes, you must carry out a walkover gas survey.

Find out how to carry out a walkover gas survey.

How often you need to monitor will depend on your risk assessment and the morphology of the site.

If you are not going to carry out monitoring, you must explain why in your permit application.

Aftercare monitoring

You may need to carry out aftercare monitoring to confirm the waste is physically and chemically stable.

If you carried out monitoring when you were depositing the waste, you must continue that monitoring for a short period after the site has closed. The length of time you do this for will depend on what you found during your operational phase monitoring.

You need the results of this monitoring if you apply to surrender your permit.