4. Site location, design and capacity
Issues to consider relating to site location, design and capacity, reducing or preventing contamination and primary and secondary containment for new and existing sites.
This section applies to all processes and operations.
1. You should consider the potential impacts on local sensitive receptors when selecting a new site.
2. You must choose the location of your site so you prevent or minimise fugitive emissions to air. This includes dust, bioaerosols, odours and other gaseous emissions including ammonia.
3. You should also consider the possible impact of climate change, especially:
- flood risk
- drought
- extreme temperatures
- other extreme weather events
Existing sites must consider the risk of climate change on their existing facilities and as far as possible have contingency measures in place.
1. The storage and handling of waste on site must be located as far as technically and economically possible from any sensitive receptors.
2. When designing your biological treatment site you must consider minimising the unnecessary handling of waste between each step in the process, from receipt, during treatment, and during storage of the final material.
3. All biological treatment facilities must be designed by a suitably qualified or experienced person. Facilities must be built to recognised industry standards.
4. You must design your plant to minimise emissions during the transfer of waste from one step to another. For example, the transfer of feedstock from reception to a feed hopper.
You must consider at the design stage where there is an opportunity to cover storage areas and where possible contain, treat and abate air using appropriately engineered plant.
5. To prevent emissions (including ammonia) you must cover digestate stores and compost liquor. Where fixed covers are used these must have a system that can remove and effectively treat emissions.
6. You must consider the location of access doors in relation to sensitive receptors to prevent loss of containment.
Reducing or preventing contamination
7. Good site design and process flow reduces the risk of cross-contamination of pasteurised or sanitised and stabilised materials.
8. You must consider the design, process flow and intended use of outputs during the planning and design stage of your plant to prevent cross contamination of treated and untreated material.
Preventing cross contamination by segregation relies on both the:
- physical separation of waste
- procedures that identify when and where wastes are stored
Primary and secondary containment
New facilities
9. When designing new plant, you must make sure that you assess the environmental impacts from the plant’s operating life and eventual decommissioning.
10. All critical structures should be designed and built to construction and design regulation.
11. All secondary containment must meet the requirements of the Construction Industry Research and Information Association (CIRIA) report C736 or an equivalent standard.
12. A chartered civil or structural engineer must provide construction quality assurance (CQA) and validate the construction of all facilities. You can use a chartered geotechnical or structural engineer for lagoon design and construction. All pipe work must be designed to allow for inspection or integrity checks, or both.
13. Drainage and vessels must be accessible to allow cleaning and maintenance.
14. You must design underground tanks to allow inspection and must have secondary containment with leakage detection.
15. You must consider the life of all plant and its decommissioning at the design stage. This includes tanks, pipework and drainage and lagoon structures.
Existing sites
16. Operators of existing sites must use a chartered engineer to carry out a detailed assessment of primary and secondary containment where it has not previously been validated to industry recognised standards.
17. You must assess containment structures against CIRIA 736. This is a risk-based assessment. Where you have not used CIRIA 736, the assessment must be an equivalent approved standard. Where improvements are identified, you must propose an improvement programme or process monitoring to make sure there are no uncontrolled process releases.
18. You should monitor underground pipe work or ducting and drainage to make sure there is no leakage.
19. Underground tanks should have secondary containment. You must implement a method of inspection and leakage detection as a minimum.
1. You must determine the actual physical capacity needed to manage, treat and store waste on your site without causing pollution.
2. You must include factors like seasonal changes in feedstock supplies and in markets for outputs.
Exceeding the site capacity will significantly increase the risks of pollution. This includes the capacity of storm tanks.
3. You must provide enough space on site to operate your plant and equipment safely, and to allow easy and environmentally safe storage and treatment.
4. Environmental permits set limits on the amount of waste you can:
- bring onto site on an annual basis
- treat at any one time
- store at any one time
To determine the daily and annual throughput, you must establish the following critical volumes or tonnes:
- waste storage capacity at any one time for both incoming waste and processed material
- residence time for waste to be fully treated and recycled