Consultation outcome

Appropriate measures for the biological treatment of waste: consultation response document

Updated 27 July 2021

1. Introduction

The purpose of this consultation was to engage with stakeholders and the wider public and invite comment on the content of our draft technical guidance ‘Appropriate measures for biowaste treatment’. Our aim was to help operators understand the appropriate measures for permitted facilities that transfer or treat biowaste. The guidance is also applicable to exempt waste activities which are required to meet the relevant objectives. Relevant objectives, in relation to waste, are to make sure that the waste is recovered or disposed of without:

• endangering human health
• using processes or methods which could harm the environment

In particular without:

• causing risk to water, air, soil, plants or animals

• causing nuisance through noise or odours

• adversely affecting the countryside or places of special interest

The guidance is not definitive and it does not prevent, limit or replace an operator’s obligation to assess appropriate measures fully and put other measures into place if necessary.

Currently, the measures and standards for permitted facilities taking biological waste for transfer and, or treatment are set out in various documents:

• Draft technical guidance documents (November 2013 Anaerobic digestion, composting and mechanical biological treatment)

• Framework for assessing suitability of wastes going to anaerobic digestion, composting and biological treatment (July 2013)

• Sector guidance note S5.06: recovery and disposal of hazardous and non-hazardous waste (May 2013)

• BAT reference documents (BREF) and best available techniques (BAT) measures for waste treatment

The proposed guidance will replace the documents listed in the first 3 bullet points. It will be published on GOV.UK.

Other guidance may also apply to biowaste facilities, for example on developing fire prevention plans, environmental management systems (EMS), odour management plans (OMP), for medium combustion plants and specified generators and for controlling and monitoring emissions.

This guidance incorporates the relevant requirements of the waste treatment BAT conclusions document, made under the European Industrial Emission Directive (2010/75/EU). This applies to waste installations permitted under the Environmental Permitting Regulations 2016.

New installations must meet the standards from the start of operations. Sites permitted after 17 August 2018 must already be meeting them. Existing waste installations (permitted before August 2018) are required to meet BAT and the associated emission limits (BAT AELs) by 17 August 2022. Where an operator is unable to comply by the deadline they have an option to apply for a derogation. Advice regarding derogations for BAT compliance is available through the Industrial Emissions Directive derogation: cost-benefit analysis tool.

The guidance provides clarification about how we expect operators to achieve compliance with the BAT conclusions. In some circumstances compliance with the BAT conclusions may be insufficient to prevent harm and in these cases the operator may be required to undertake additional measures.

There is overlap between BAT for waste installations and necessary measures for waste operations. The Environment Agency uses the term ‘appropriate measures’ to cover both sets of requirements. Exempt waste operations must meet the relevant objectives as set out in the Introduction. This guidance indicates the appropriate measures for exempt biowaste transfer and treatment operations.

Some measures may not be suitable or relevant for your operation. Appropriate measures will depend on the:

• activities being carried out

• size and nature of the activities

• location of the facility

We will implement the guidance for new permitted facilities through the environmental permit application process. For existing facilities, we will do this through staged permit reviews. We have also reviewed the existing standard rules that apply to biowaste transfer and treatment operations. The review ensures that those standard rules provide an appropriate level of environmental protection and include the appropriate measures and standards. The revised versions will be published shortly.

Once published, the guidance will apply to all biowaste operations.

2. How we ran the consultation

In 2013 we produced draft guidance documents with industry’s contribution and those documents are considered by the industry to be sound technical guidance. The draft guidance merges 4 previous documents specifically relating to biowaste.

In 2018 we met industry representatives and trade bodies to review regulatory compliance issues and seek views on how we could achieve improvements. The industry strongly favoured formally publishing appropriate measures guidance and revising permits. We agreed to consult industry in a call for evidence which we undertook in 2018, and in 2019 we consulted on revised standard rules.

We shared a pre-consultation version of this guidance with key stakeholders including the water industry in the summer of 2020. We incorporated suggested amendments prior to the formal consultation.

We ran a formal online public consultation on the Environment Agency Citizen Space website over a 6-week period between 10 July and 21 August 2020. We also received responses by email which we have incorporated into the responses.

We asked 15 questions relating to specific aspects of the draft guidance (technical questions 4 to 15 of the consultation). We also asked for additional comments. We have reviewed all of the comments and suggestions and will amend the guidance as appropriate.

A list of the names of organisation that responded to the consultation is in the Annex at the end of this document. We would like to thank all the respondents for their time and contributions.

3. Summary of the main findings and our actions

The format of the guidance received a mixed response. Several respondents thought the document should be structured so that different processes are addressed separately. Alternatively that we provide a table to indicate when specific measures apply.

Some stated that the guidance adopts ‘a one size fits all’ approach whilst others said that they were supportive of standardising and simplifying guidance across the sector. The majority pointed out that there are differing levels of risk within the sector and a risk-based approach should be used in applying appropriate measures.

We agree that some measures are not relevant to all biowaste treatments and consider that section 2 of the guidance explains when appropriate measures apply. However in light of these comments we will review the guidance and make amendments where it appears appropriate. The BAT conclusions remain mandatory for installations.

There was no clear consensus regarding the process monitoring requirements. Several respondents expressed concerns over the detailed level of process monitoring suggested, especially for anaerobic digestion (AD) processes. However others supported robust process monitoring and considered this should already be standard practice.

We considered all relevant technical responses and will amend the text where appropriate. However we note that other industry standards and documents indicate the importance of good process control and believe this to be standard practice.

Some respondents felt that operators should be given time to implement changes to secondary containment requirements. There was a clear perception that existing sites would be required to retrofit secondary containment to CIRIA 736 standards. We have made it clear that the requirement to ensure secondary containment to CIRIA 736 standards applies to new sites. Existing facilities such as water industry sludge digesters are unlikely to be designed and built to a CIRIA 736 specification. In such cases we expect operators to evaluate primary and secondary containment to ensure it is fit for purpose and use alternative means to achieve an equivalent standard. All sites must be assessed by a chartered engineer.

Some respondents appeared unclear about waste characterisation and duty of care requirements. There were some comments expressing concern at the rigour of assessment for bespoke and novel wastes. Waste characterisation must be undertaken to fulfil duty of care requirements. Our existing framework for assessment of novel and bespoke wastes has been incorporated into the guidance. This represents a continuation of current practice and not a tightening of requirements. We are concerned at the lack of awareness of existing legal obligations. All wastes accepted must be suitable for biological treatment and not simply to blend and dilute in another bulk material. The majority of output from the biowaste sector is used on agricultural land used for food production so this is a critical consideration.

We received many comments about the storage and covering of digestate and liquors. Some felt that we were not joined up with Department for Environment, Food and Rural Affairs (Defra) and Department for Business, Energy and Industrial Strategy (BEIS) and that it is not the Environment Agency’s remit to control pollution to air. We are working closely with Defra and BEIS on the need to reduce emissions and balancing this with the need to divert biodegradable waste to recovery. Ammonia emissions are addressed in the Clean Air Strategy and responsibility for controlling emissions from permitted facilities lies with the Environment Agency. We are clear that it is necessary to control and mitigate ammonia pollution.

Respondents commented on the need for contingency measures when the land bank is not available, or where the facility is not fully functional, for example, for equipment failure and incidents.

One contingency measure mentioned in the guidance was to stop or reduce the acceptance of feedstock. Some respondents felt this was either excessive or not practicable. We accept that some processes such as sewage sludge digesters cannot easily be turned off although sludge can be diverted elsewhere. However we will retain this in guidance as it is a measure that operators must consider. Planning for contingencies is critical to compliance. A facility should not accept waste it does not have the capacity to legally treat then store or export. Contracts to receive and dispatch waste should be designed to accommodate such contingencies. In recent years wet and extreme weather has severely impacted the sector’s ability to manage materials and being climate change ready is becoming increasingly critical to business continuity. Contingency planning is a must do.

Some water companies commented that the August 2022 timescale set out for BAT compliance was unlikely to be achievable. They believe any significant capital works should form part of the next ‘water industry national environment plan’ (WINEP) and compliance timescales should align with the water industry 5-year business planning cycle. We disagree. The WINEP does not determine regulatory compliance deadlines which are laid down in legislation. Water companies were informed in July 2019 of the need to obtain environmental permits for their sludge digesters and in exceptional circumstances will allow until the end of 2024 to meet BAT requirements. This represents a 5 and a half year lead in period for compliance.

We will review and make changes to the guidance where we believe it is appropriate. These changes will provide greater clarity on how and when the guidance applies, will drive improved environmental performance and reduce impacts to the wider environment, whilst minimising the business impact.

We aim to publish the revised guidance in early summer 2021. We may respond to individual company specific comments where this is deemed necessary.

4. Responses to ‘about you’ consultation questions (1 to 3)

Q1 Are you responding as an individual or on behalf of an organisation or group?

We received 29 responses to the consultation:

• 25 responses on behalf of an organisation or group

• 4 responses from individuals

A list of respondents is provided at the end of this report.

Q2. We asked if responders would like to be updated.

28 responders wished to be updated and they provided their contact details. We will ensure we update them on progress. We aim to publish the revised guidance in summer 2021.

Q3 We asked if we could publish responses

26 confirmed their responses could be published (4 individuals and 22 groups or organisations).

3 organisations stated that we could not publish their responses because of:

• confidentiality
• the impact of COVID-19 on internal stakeholders

See the list of organisations that responded to the consultation in the annex at the end of this document.

5. Responses to consultation questions (4 to 13)

Q4 We asked whether the guidance was clear about which sites have to follow the guidance.

We received 25 responses:

• yes – 12

• no – 11

• do not know – 2

There were 16 responses providing further information.

a) Two respondents commented it was not clear on which sites the guidance applied to, commenting that the guidance needs to be divided into subsections for each process type. One respondent suggested a matrix to show what applies to each process.

b) One respondent said that attempting to provide all-encompassing guidance caused greater uncertainty along with references that say ‘some measures may not be suitable or relevant to your operation’. Although some sections refer to specific operations, others do not. With the addition of apparent repetition and cross over of topics between references and unreferenced sections and those with, and without, subheadings the overall picture is unclear in many areas.

c) One respondent stated that the terminology was confusing, stating the use of the term ‘must’ for many requirements and in some places stating some measures ‘may not be relevant’, left the document open to interpretation. Suggesting that there needed to be development of appropriate sectorial, or possibly sub-sectorial, guidance.

d) Several water companies asked for clarity regarding what activities the guidance applied to. For example whether or not other activities at waste water treatment works (WwTW) such as dewatering sites, tankering of domestic wastes (cess and septic), and interworks tankering are captured. Clarity was required on which parts of sludge treatment centres are included in Waste Framework Directive (WFD) or excluded under Urban Waste Water Treatment Directive (UWWTD) and Sludge (Use in Agriculture) Regulations (SUiAR), for example, liquor treatment plants, biosolids cake pads.

e) One company stated that the definition of a lagoon versus a tank is not clear.

f) One trade body stated that the term ‘fibre’ should be clarified.

g) Two companies questioned the term ‘low cost improvement’ stating that assessment of risk or aggregated costs across sites had not been taken into account.

h) One water company felt that the timescales and investments required where the industry was only recently identified as failing under the Industrial Emissions Directive (IED) was totally unreasonable.

i) One water company commented on the applicability of the guidance for AD operations involving energy crops which were not ‘waste’ and asked that we advise what regulation is applicable to such activities as these must surely represent similar environmental risks in terms of emissions and escapes, and comparable obligations and enforcement should apply.

Our response

a) and b) The guidance applies to 800 separately permitted facilities (and a much larger number of exempt facilities) covering biowaste transfer, digestion and composting activities. They differ widely in their complexity, scale, location and age. We accept that these differences will result in diverse risk profiles and this is acknowledged in the guidance which states that:

“Some measures may not be suitable or relevant for your operation. Appropriate measures will depend on the:

• activities being carried out

• size and nature of the activities

• location of the facility”

Despite this some generic measures do apply to most facilities, for example EMS and waste acceptance procedures.

We will not be providing sub-sectorial guidance. We consider that the operator is best placed to understand the risk profile of their activities and should take responsibility for applying the guidance to their site. This offers some flexibility but also requires that the guidance be read in context. Operators will inevitably need to exercise some judgement in deciding what constitutes appropriate measures for their facility.

We will however review the guidance to remove duplication and where possible offer further clarification about which measures relate to specific processes.

c) The term ‘must’ is used to make clear that operators are required to demonstrate that a measure or measures have been considered. Where appropriate the operator can demonstrate that the measure is not relevant, or can justify an alternative measure which provides an equivalent level of environmental protection.

d) The guidance is clear that waste water treatment processes at UWWTD facilities are not regulated under IED or WFD. However tankered effluents arriving at these facilities are controlled wastes and their acceptance at the works requires an environmental permit. These permitted facilities are subject to the guidance. For clarity the pre-assessment and acceptance criteria in the guidance do apply to the importation of effluents to the head of works.

Sewage sludges transferred between works and cess and septic tank wastes are controlled wastes whilst in the tanker but can be discharged to the head of works without a permit. The guidance does not apply to these activities unless the wastes are mixed with other effluents.

Liquor treatment and sludge treatment and storage facilities are waste operations regardless of whether they are co-located with UWWTD facilities and are therefore subject to the guidance.

Using aeration and activated sludge treatment methods to treat industrial waste waters falls within the definition of biological treatment so this guidance does apply to these facilities.

Sludge dewatering is not biological treatment so not subject to this guidance unless it is a directly associated activity at a biological treatment installation.

This is a complex area of regulation. Where there is any uncertainty relating to specific activities we will continue to advise water companies through the usual channels.

e) We will amend the text to clarify. The definition of tanks and lagoon containment are clearly laid out in CIRIA 736.

f) A fibre is the solid fraction from a digestate and should be able to be stacked. We will amend the text as appropriate to clarify.

g) Examples of low cost measures that can be easily implemented included improved signage, maintenance schedules, temperature and process monitoring, and procedure or document reviews such as OMP or EMS.

h) The BREF and BAT were published in 2018 with a legal deadline for compliance of August 2022. We confirmed that water companies would need to comply with BAT in July 2019. We consider that there has been ample time to prepare. However we recognise that for a small number of sites the deadline will be challenging because of the need to carry out significant infrastructure improvements. In these cases we will consider using improvement conditions to allow limited extensions. Where operators consider they are unable to comply with BAT requirements by the end of 2024 they will need to demonstrate that they meet the criteria for a derogation.

i) Anaerobic digestion of energy crops is not subject to waste regulation and therefore out of scope of the guidance. We agree that anaerobic digestion activities pose broadly similar environmental risks regardless of the type of feedstock. The question of whether energy crop digesters should fall under similar permitting requirements to waste digesters is a policy matter which is outside the scope of this guidance but we will raise the matter with government.

Q5 Are there additional measures that you think we should include in the environmental management system section to protect people and the environment for biological treatment of the waste sector?

We received 25 responses:

• yes – 4

• no – 18

• do not know – 3

16 respondents provided further comments.

Summary of responses

a) The insurance and engineering sector said that sections regarding pressure relief and vacuum systems should be more robust. They further commented that as many pressure vacuum systems are not designed to a standard, this required increased focus on maintenance and inspection checks. The insurance sector also expressed concerns about the need for lightening conduction requirements.

b) One respondent suggested that the EMS should be audited and accredited annually by independent external third party. Overall the industry welcomed the inclusion for all sites to have an EMS, ensuring a level playing field. One company responded that they had accredited ISO 14000:1 and felt that if too much was prescribed in the EMS section of the guidance which could prohibit the progressive nature of this internal standard.

c) We were asked to clarify how much detail small sites need in the EMS and whether an EMS be used over multiple sites with the same process.

d) One water company added that several new named documents are identified but it is not clear if they are relevant to all AD sectors, and clarity is sought on this point. For example ‘Leak Detection & Repair Plan’ and ‘Residues Management Plan’.

e) The same respondent stated that creating and maintaining an ‘inventory of waste water and waste gas streams’ needs further definition to see that it is adding real value, prioritised to any significant pollutants, and that accompanying monitoring requirements are not unduly onerous. A ‘fugitive emissions plan’ also needs to be realistic in terms of what it can practically contain or abate.

f) The same water company considered that the EMS and its content should be the responsibility of the operator, and the prescriptive list blurs the distinction between guidance and mandatory requirements.

g) Some respondents commented that the level of details in pre-acceptance and acceptance of waste was too much. We received extensive comments from the waste water industry sector regarding waste acceptance and the cost of upgrading assets to a standard.

h) Some respondents expressed concern regarding potential inconsistency that may develop during Environment Agency compliance visits.

i) It was claimed that following manufacturer’s guidance will duplicate maintenance and cause increased down time. For example conducting engineering checks on some tanks every 5 years would cause unnecessary down time and loss of revenue.

j) One respondent commented that the ‘Emissions Control’ section may fit better under the management system section compared to where they are located within the document now – odour, pests, noise and vibration, and waste minimisation.

k) One water company questioned the relative roles of the Environment Agency and other regulatory bodies such as the Health and Safety Executive (HSE). It was suggested that fire and explosion prevention are within the remit of the HSE and not the Environment Agency.

l) One water company responded that the need for waste characterisation does not necessarily apply to biosolids (meaning biosolids produced from only UWWTD treatment, with no co-digestion). They stated that the current instrument, the SUiAR allows for land recycling with no further waste controls, and that this is expected to remain the case by the development of an assurance scheme as stipulated by the Environment Agency strategy for safe and sustainable sludge use published on 15 July 2020.

Our response

a) We have revised and expanded the section on pressure relief and vacuum systems and the assessment to address lightening.

b) The EMS must incorporate details about how the site is managed and how emissions and pollution is prevented dependant on the risk profile and inventory. With regards to the suppression of developing internal systems we do not think this is the case. An EMS is a live document that is meant to be regularly reviewed.

c) For all operations, including smaller ones, the EMS must ensure there is sufficient control to prevent pollution and ensure compliance with the permit. Less complex activities may require a less detailed EMS. We will amend the guidance to clarify the use of an EMS across multiple sites. As respondents have made clear every site is different and whilst the EMS can be applied across multiple sites some elements of the EMS may need to be site specific.

d) We confirm that these documents are relevant to all AD sectors.

e) The inventory requirement is derived directly from the BAT conclusions but it is also best practice. We refer operators to the BAT and BREF for further detail. A fugitive emission plan should be comprehensive. It should identify all potential sources of fugitive emissions and detail measures to minimise them. Where these measures are limited by practical or other constraints this should be noted and justified within the plan.

f) There has been detailed industry guidance available since 2008 (The Composting Association 2008) and more recently the anaerobic digestion industry has produced guidance on good operational practice and have developed schemes to assist operators. The adoption and implementation of an evidenced and documented EMS that is regularly reviewed is not a new concept. In our experience where site procedures, processes and maintenance regimes are not rigidly applied the results can significantly impact on the environment and local communities and in some extreme cases result in loss of the plant.

g) Pre-acceptance and acceptance procedures are not new. We produced guidance in 2013 to enable the biowaste sector to accept novel types of wastes. This guidance is simply being incorporated into the main guidance document. It encompasses obligations under the duty of care and the environmental permit. The principles are protective of the biological treatment process and the environment and ensure that only wastes which are suitable for and capable of treatment are accepted. They also prevent the dilution and dispersion of pollutants by mixing with bulk wastes. Installation permits will already be compliant with the requirements as specified in SGN 5.06.

h) No rationale was provided to support this concern. We will ensure that our staff continue to receive training based on this guidance and believe this revision of appropriate measures will improve consistency.

i) We believe that following manufacture’s guidelines is best practice. Manufacturers understand the design characteristics of their plant and are best placed to determine operation and maintenance parameters. Not following manufacturer’s recommendation introduces unnecessary additional risk. Protecting revenue is not an acceptable reason for cutting corners. Where manufacture’s recommendations are critical in relation to design and tolerance parameters of the plant or where a failure to do so negates insurance cover then they must be followed. Where there is a deviation this should be done in line with assessment such as the Hazard and Operability Analysis. If an equivalent approach is shown to ensure safe and effective operation and integrity of plant infrastructure without increased environmental risk or consequence this must be outlined in the EMS. In such cases an alternative maintenance and inspection regime can be fully documented and implemented.

j) The document is written to ensure permit compliance and emission controls apply across a range of control points. However, where emissions are regulated under the permit and limits applied then we believe these warrant separate and identified measures.

k) The EMS must cover all aspects of operations which may impact on the environment. Clearly fire and explosion prevention is a fundamental aspect of site safety but the evidence shows that fires and explosions at waste facilities can also cause significant environmental harm. We expect the EMS to address and minimise these risks. Non-compliance with HSE regulations, for example, lack of Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) assessment or signage, can prevent us safely inspecting facilities.

l) This interpretation of the SUiAR is incorrect. Sewage sludge is a waste. The regulations, which are lex specialis, make the landspreading of sludge as a waste subject to specific rules. Regulation 3(7) of the SUiAR requires the sludge producer to ensure sludge is used in such a way that account is taken of the nutrient needs of the plants and that the quality of the soil and of the surface and ground water is not impaired. This can only be achieved by characterising the waste prior to its use. The role of any assurance scheme is also misunderstood as it will not change the waste status of sludge.

Q6 Are there measures included in the environmental management system section that you feel are not relevant to the biological treatment of waste sector?

We received 24 responses:

• yes – 7

• no – 11

• do not know – 6

16 responses were received detailing further comments.

Summary of responses

a) Many comments were in relation to concerns that the Environment Agency is expecting retrofitting of critical infrastructure and additional secondary containment.

b) There was comment from 2 water companies regarding ‘avoiding underground pipework’, or to include secondary containment or monitoring underground pipework. Comments related to secondary containment not being feasible for existing pipework and other underground assets. By moving underground pipework above ground, there would be an increased need for pumping (adding to the carbon footprint of the process) and the added risks of failure of this additional equipment.

c) One water company stated that with regards buffer storage capacity, water company assets operate on a continuous basis with very limited ability to close the process therefore this section should not be applicable. Assets are designed with a degree of capacity for emergencies and the material processed is low hazard. Another stated that water companies operate on a continuous basis therefore ceasing to accept waste is not an option and where there is excess gas the use of a waste gas burner (flare) is used.

d) One water company stated that more detail is needed on remote monitoring of alarms.

e) One respondent stated that the reference to abatement of emissions from safety relief valves and bursting discs should not cause their operation to be restricted as this may result in unsafe practices. It was suggested this be clarified to remove any ambiguity.

Our response

a) We have stated that we do not require retrofitting on existing sites. We require that all critical infrastructure is fit for purpose, inspected and maintained so that it remains fit for purpose. Where it cannot meet a standard, and we have suggested CIRIA 736 as the industry recognised standard, then the operator must put in place an improvement plan or additional measures as recommended by a chartered engineer (or both) that achieve an equivalent standard. Our standard rules permits have required all containers to be within a bunded area. A bunded area is secondary containment, so should therefore have the ability to contain polluting material.

b) We have not stated that underground pipe work should be replaced, but it should be avoided wherever possible. Underground pipe work is difficult to monitor, inspect and repair. Where underground pipework continues to be used there must be regular maintenance checks and leak detection measures in place to minimise the risk of leaks and ground contamination.

c) We have suggested a range of contingency measures including as a last resort diverting the waste elsewhere. Continuing to accept waste at a facility with no capacity or with severe operational difficulties is often the root cause of non-compliance. Particularly with issues around odour and pollution. Where diversion is not an option we expect operators to put alternative contingency measures in place. This is usually possible for some wastes within the network of waste water treatment works but we accept this may not always be the case. For some operators it will be essential to manage sludge and other organic outputs in periods when there is no access to the land bank. Biogas production contingency planning is necessary because national gas networks are under pressure. Frequent disposal of gas by flaring is not an appropriate long-term contingency for gas overproduction.

d) Remote alarm monitoring may be set up on a case-by-case basis as long as the technical and maintenance personnel have access to alarms when the site is not manned.

e) The appropriate use of safety systems is already covered by the guidance which states that ‘If this is not advisable on safety grounds, you must focus attention on reducing the probability of the emission’. In our experience a significant percentage of systems are poorly designed or unfit for purpose and there is considerable scope for improvement. It is incumbent upon the operator to ensure that pressure relief devices are designed and operated in a manner which does not result in unnecessary biogas loss. It is inefficient in terms of energy recovery and in some cases the significant losses of methane, a powerful greenhouse gas, undermines the environmental benefits of AD.

Q7 Do you think that the measures in the guidance are appropriate for the commissioning of biological treatment plants?

We received 25 responses:

• yes – 11

• no – 9

• do not know – 5

Most responses felt this section was satisfactory but there were some notable technical suggestions which we have included in the guidance or amended. We received 17 further comments about this section. There were no clear improvements or suggestions about how safe commissioning could be achieved.

Summary of responses

a) Many respondents commented that commissioning is site and plant specific. One water company commented that many of the capital schemes are delivered to multiple external stakeholder dependencies and are therefore complex and often working to tight time constraints. They went on to say that they were concerned about the potential delays which could result from another external dependency and the knock-on impacts on the outputs and delivery of the projects. They added that clarification would be useful regarding commissioning or decommissioning plans in relation to which ‘plant or equipment’ is to be included (AD, CHP, gas to grid, flares, storage tanks). One respondent stated that commissioning is not relevant to open composting operations.

b) Two water companies asked for clarification about the definition of a ‘period of dormancy’ and went on to seek clarity if this applied to tank inspections or cleaning, and to thermal hydrolysis plant (THP) and combined heat and power plant (CHP). They wanted further clarity as to the necessity for a full commissioning plan to be undertaken each time. They stated that increased tank inspections would be a huge burden, especially if the Environment Agency want to sign off each one.

c) Two water companies commented on the need for a decommissioning plan in relation to what was deemed ‘satisfactory condition or state’, and went on to ask who is qualified to decide this in each case. One added that a number of their sites are located on historically contaminated ground and site condition reports are not available. Others stated that decommissioning guidance is not considered appropriate and considered onerous.

d) The use of lithium tracing in AD was supported by some but not by others due to residence time and the structure of the tanks.

e) One respondent stated that, in terms of commissioning and the use of inoculum, that where more novel waste inoculum was used it may have to travel long distances and inoculum can be in short supply. They went on to state that it was more useful to say the inoculum should be compliant with the permit where possible. This will ensure that commissioning can take place in a timely manner and reduce the cost and the distance associated with transport. One respondent stated that permit applications take more than a year and causes difficulty in planning commissioning due to the uncertain nature of permit issue.

f) One a water company stated that when a refurbished plant requires re-seeding a U6 exemption is required. The current U6 exemption does not contain the new European Waste Catalogue (EWC) codes we have been asked to use, for example, 190206. It would be helpful if the exemption application could be updated to include the latest EWC codes.

Our response

We have noted the comments received and amended the technical text where appropriate.

a) This section is not exhaustive and there will be instances that where specifics of the plant and its location will need to be considered. Commissioning or recommissioning needs to be carefully managed, with the design and construction regulations and commissioning fundamental to any project. These activities require a process management approach and cannot be dealt with in an ad hoc fashion. Our guidance is based on industry best practice and nothing should be contrary or additional to a well designed and executed commissioning or decommissioning plan. We expect to see the sign-off for each commissioning phase but this will not cause any delay as this documentation will already be required for other purposes. The complexity of any commissioning plan is dependent on the complexity and location of the site. Even for composting operations there are instances where equipment and plant need to be commissioned, for example, shredders, air abatement and leachate management systems. These activities must be managed and documented.

b) On the question of scope, decommissioning and re-commissioning is relevant to any plant covered by the permit, or which will have a direct impact on the operation of the permitted facility. A plan needs to cover the extent of the dormancy and complexity of the process and equipment being brought back into commission. It will include emptying, inspecting and recommissioning a digester, this is a significant and technically complex activity. We will amend the text to clarify. The Environment Agency does not seek to approve each plan but requires evidence that the operator has identified all potential risk and put procedures in place to remove those risks. We consider that a qualified chartered engineer would provide an appropriate level of sign off. We are unclear why reference to increased tank inspections has been raised here.

c) Decommissioning is a necessary and important stage in permit surrender and should be considered throughout the operational life of a facility. Failure to do so means more work on surrender. Site condition reports are required at the permit application stage so each permitted facility will have one. At the end of the operational life of the facility the operator must produce an evidenced decommissioning proposal which enables them to proceed to surrender. The guidance provides a framework rather than a binding set of requirements. Further guidance on site condition reports and how to surrender permits can be found on GOV.UK.

d) We have amended the text regarding digester mixing efficiency to provide lithium tracing as one recognised procedure and included other recommendations.

e) We note the comment regarding permit issue time. Where the determination of permit applications for new sites are delayed we find this is generally due to incomplete information being submitted. This guidance should enable an applicant to provide sufficient information and therefore reduce permit assessment time. However, for existing operations this should not be an issue. Decommissioning and recommissioning digesters or key plant should be planned activities. Aspects of AD feedstock and organic loading should be within the business planning of the site and not considered simply to meet a tariff guarantee date.

f) We will explore whether it is possible to amend the U6 exemption. We will also review RPS231 and where possible amend it to cover the interim period.

Q8 Do you think that having and implementing a contingency plan that meets the requirements of the proposed guidance should be an appropriate measure?

We received 25 responses:

• yes – 15

• no – 9

• do not know – 1

We received 16 further comments regarding this question.

Summary of responses

a) Most respondents supported the need to have robust contingency plans. In particular it was recognised that for off-farm waste-fed AD, planning for volatile weather would help the agriculture sector meet the compliance requirements on storage for nitrate vulnerable zones (NVZs) and farming rules for water (FRfW). It was also recognised that sites need to have alternative storage arrangements in place for times when the agricultural land bank is not available. One company said that while they cannot plan for all eventualities they do need to think about which scenarios present a risk.

b) Several respondents and trade bodies commented that ceasing to accept waste incurs potentially large costs and loss of customers and contractual issues and may affect process stability in AD and an have adverse implications that are not related to gas management.

c) Two water companies said while they recognise that contingency plans are a normal part of planning processes in order to ensure risk is managed and critical activities maintained through abnormal circumstances. However, they did not believe that they should constitute an appropriate measure. They went on to state that a requirement for formalised contingency plans should be proportionate to the level of risk, and where required, guidance should enable operators to consider risks and measures appropriate to their operation and not prescriptive in detail. For water companies dealing with inter-site sludge movements internalised to their own business or catchment (that is, satellite to hub works import), the non-hazardous nature of the waste means that the accompanying level of risk is already inherently low. Many sewage plants, when land bank is limited, will seek alternative arrangements to avoid the need to stop accepting waste. One responder stated that the onus should not be on the treatment facility. Stating that waste carriers and producers also have an obligation to prepare. Another stated that it was not necessary for a waste producer to see the permit and that they should not have to be informed of the details of the contingency planning.

d) One operator felt that storage of material that fails end of waste classification is a matter for the Animal and Plant Health Agency (APHA) and PAS110.

Our response

All new facilities will have to demonstrate they have adequate storage available.

a) As the biowaste sector matures and weather patterns change the need for contingency planning has become more urgent. We acknowledge that not all eventualities can be planned for but it is the responsibility of waste producers and permit holders to minimise those risks by planning for foreseeable adverse events.

b) Contingency planning is a core business activity which protects operators from significant risks. We agree that there are sound business reasons why ceasing to accept waste or diverting waste should be actions of last resort and with good contingency planning they can be. Contingency planning can minimise the risk of having to take these actions and suffering any consequential losses or contractual issues. Sharing contingency plans with waste producers and working together is best practice and prevents the producer or holder of waste committing duty of care offences or permit breaches.

c) We consider contingency planning to be central to risk management and therefore an appropriate measure. For installations contingency planning is necessary to achieve compliance with aspects of BAT. Plans will vary in complexity but must be sufficiently detailed and robust to address the risks associated with the activity and the waste being handled. The guidance is deliberately not prescriptive in this regard but does provide a framework for operators. Classifying sludge as low risk simply because it is classed as non-hazardous is overly simplistic; there are many examples where sludge has caused environmental harm. We accept that the production of sludge cannot be avoided but this simply emphasises the need for sludge producers to make robust contingency arrangements. This responsibility cannot be passed on to other parties. We accept that water companies cannot stop accepting waste via the sewage systems but other tankered waste inputs may need to cease or be diverted elsewhere to manage risks.

d) Waste which fails to achieve end of waste continues to be regulated as a waste and is therefore our concern. Also we are the competent regulatory body to support (or not) certification schemes. We work with the APHA as E. coli and salmonella failures are a concern and result in a zoonosis notice.

Q9 Do you think that obtaining details about who the waste producer is should be an appropriate measure?

We received 26 responses:

• yes – 16

• no – 9

• do not know – 1

We received 21 further comments regarding this question.

The majority of responses considered this to be fundamental in compliance with waste acceptance and waste description and ensuring that waste producers comply with regulatory requirements. Contamination control, was welcomed by most respondents.

Summary of other comments

a) One water company said that without further clarity on which waste streams this applies to it was difficult to comment.

b) Some responders felt it was up to the operators to understand the risk and that the measures where impracticable and gave an example of ‘portaloo’ waste. They went on to state that the ‘producer’ and subsequent holders (that is, person or persons responsible for the collection and transfer of waste from point of production to point of reception) have met their duty of care requirements it may not be possible for the operator to contact the producer or obtain their details as relevant information will have been provided to enable safe acceptance and treatment. They felt this waste acceptance measure was an unnecessary administrative burden.

c) One operator said that pre-acceptance and collecting the information may mean that waste cannot not be processes for some days. This should be done in initial or proposed supply with periodic checks. The checking of paperwork was too onerous for small AD operators.

d) One operator stated that they, the operator, should be able to choose what characteristics and testing is applicable to their process and waste feedstocks. It is not feasible to have all the proposed analytical checks carried out and these should be used as an example.

e) In relation to reduction of ammonia and controls in feedstock - one trade body responded that this should be aligned to legislation that Defra will put in place to implement the clean air strategy. They stated that for some operators covered storage will be impossible without Defra support. The measures proposed may encourage sites to cease taking feedstock like chicken manures. Covering will be too prescriptive they felt that measures used in pig and poultry sector should be used such as reducing the ratio between emitting surface area and volume of the manure heap or using a three-sided wall. Others responded that OMP and risk assessment are sufficient.

f) One respondent stated that holding stable high energy waste for longer than 5 days should be permissible for example powdered off-specification food waste.

g) With regards prevention of cross contamination, one respondent considered that segregating waste is not always feasible and are often blended to feed to digesters.

h) One respondent stated that washout certificates should not be required for bulk containers each load.

i) One water company stated they had little control of bespoke waste arriving at site. They commented that this document should only apply to bespoke wastes being imported directly into a sewage sludge facility, rather than the UWWTD facility.

j) Two water companies stated that they were not able to keep representative samples on site due to the volume of samples. The data set and requirement are too large and will distract operators from the management of the site. Smaller site will not have a computerised tracking system. This is a comprehensive and detailed requirement. Where a sludge treatment facility is only accepting sewage sludge wastes we would question whether the requirement for such a system is cost beneficial.

Our response

a) This applies to all waste streams unless the method of collection or treatment makes it impossible in which case checking the duty of chain care is sufficient. Waste characterisation, coding and accurate description are fundamental to the pre-acceptance, acceptance and segregation and are legal requirements and necessary to comply fully with a permit. The Waste (England and Wales) Regulations 2011 and 34(5) of the Environmental Protection Act 1990 set out the requirements.

b) We agreed with the comment about portaloo waste streams which is an example covered in comment a) above. We will amend the appropriate text. However we do not consider that isolated examples where the measure does not apply, means it is not a valid appropriate measure. Nor can we accept the measure is an unnecessary administrative burden. Assurance about the type of waste being received is fundamental to safe waste management.

c) The purpose of pre-acceptance is that it is carried out when the waste producer contacts the facility and should not cause hold up when that waste is agreed as permitted and suitable. Waste tracking requirements represent best practice regardless of the size of the operation and are critical for permit compliance and quality assurance for the end user.

d) The duty of care recognises that waste producers are best placed to understand their waste and the characteristics it is likely to possess. Having this information allows the operator to manage their process more effectively. Receiving wastes without full information about their characteristics increases the risk to the plant and final product quality. The parameters given in the guidance indicate what would typically be required.

e) The requirement to reduce and minimise ammonia and other emissions goes beyond odour management. We agree that these measures described in the guidance will be part of a management system or risk prevention. We are working with Defra and they are fully acquainted with changes we have made to permits and this guidance.

f) High energy dry waste which is sealed or contained may present a lower risk of odour. If supported by a risk assessment then we agree these could be kept for longer periods as set out in an OMP and waste inventory.

g) Segregating waste is best practice and essential where wastes are incompatible. It is also required where animal by-products are accepted. However the guidance also recognises that wastes may be blended prior to being fed into the digestion process.

h) Wash out certificates are required for untreated animal by-products and the transportation of commercial and hazardous waste. The full characterisation and knowledge of the waste received should be paramount to the process controls on site. Cross contamination can compromise this. The guidance states that in some circumstances a declaration of the previous load may be sufficient.

i) Operators should only import wastes into their facilities if they can show their treatment process can treat the waste effectively. Allowing unsuitable wastes to be received would effectively sanction dilute and disperse activities and would distort the market against operators of more suitable treatment facilities. Placing controls upon the types of bespoke waste entering water company facilities also provides some reassurance about the quality of the sludge produced. This is important to both the end user and to anyone accepting the sludge for further treatment. It also ensures that legal obligations on restricting persistent organic pollutants are observed. All these factors are equally true for imports to the head of waste water treatment works and to sludge treatment facilities.

j) Much of the on-site sampling and analysis can be avoided by implementing comprehensive pre-acceptance procedures. For installations it will be necessary to operate a waste tracking and inventory system in order to comply with BAT 2c and 4b. Where site specific difficulties arise alternatives can be proposed to ensure an equivalent standard to BAT is achieved.

Q10 Do you think that the requirement to install secondary containment that is built to a recognised standards should be an appropriate measure?

We received 24 responses:

• yes – 8

• no – 14

• do not know – 2

We received 20 detailed comments

Summary of responses

The fact that two thirds of respondents did not recognise the importance of secondary containment in protecting the environment is alarming. Containment is a fundamental principle in pollution prevention at industrial sites, waste management facilities and even in domestic settings, for example double skinned or self-bunded heating oil tanks. In the vast majority of settings relying solely on primary containment is not an acceptable option. Secondary containment is both an appropriate measure and for installations a BAT requirement.

a) One water company stated that CIRIA 736 is not wholly necessary or appropriate for the water industry which already uses high engineering standards.

b) A number of respondents commented that full compliance with CIRIA 736 may not be achievable at some existing sites but was appropriate for new sites. They suggested that a risk based approach should be taken at existing sites with an option to put in place systems to reduce the risk of pollution, such as a greater number of tank inspections and comprehensive maintenance procedures.

c) Several water companies recognised that secondary containment is a BAT requirement but stated it would be significantly challenging to retrospectively install secondary containment by the August 2022 deadline. They suggested that a phased approach in line with water industry asset management plans (AMP) funding cycles should be considered.

d) One respondent stated there is over reliance on CIRIA 736 as a document developed for the petrochemical industry and is not for use on the waste sector.

e) A number of respondents stated that the requirement for secondary containment should not be default approach. One stated that in some cases they would be relying on tertiary containment as it was not possible to retrofit secondary containment in some facilities. Others stated that the use of risk-assessment as an alternative to CIRIA 736 does not come across clearly enough in the guidance.

f) Another water company asked for clarification on the requirements for above ground tanks applies to pre-existing tanks and below ground tanks. Stating that this requirement should be subject to risk assessment on pre-existing infrastructure to demonstrate the benefit of such extensive investment. They further commented that this should be within the AMP funding cycle. They further commented that this contradicted the section that states ‘avoid using underground tanks and pipework - if it is not economically possible to replace them, you must protect them by secondary containment or a suitable monitoring programme’.

Our response

a) CIRIA is the industry standard and provides a benchmark against which alternative schemes can be measured. We are aware that the water industry uses the Civil Engineering Specification for the Water Industry (CESWI). The industry has been invited to demonstrate that this is equivalent to CIRIA 736. However it is apparent that water companies apply CESWI in different ways. It is also clear that CESWI is an engineering specification and because it does not adequately address environmental risk some water company assets built to CESWI specifications lack the containment measures that would enable them to meet BAT.

b) This is entirely consistent with BAT and with our guidance. We expect new facilities to be designed and built to CIRIA 736 standards. At existing sites we recognise that retrofitting may not be viable so alternative mitigation measures may be required to achieve an equivalent level of environmental protection. The guidance explains that ‘operators of existing sites must use a chartered structural or civil engineer to undertake a detailed assessment to identify if additional infrastructure improvements are required to protect the environment’.

c) The August 2022 deadline for BAT compliance is a legislative requirement and water companies were informed in July 2019 that their sludge biological treatment facilities would need to comply with BAT. We have noted above that retrospective installation is not necessarily required at existing sites. We will consider using improvement conditions for major works but these will not extend beyond the end of 2024 at the very latest. Compliance with legislation is not conditional on funding. Funding is out of scope of this consultation and funding questions should be directed to the Water Services Regulation Authority (OFWAT).

d) CIRIA is based on the widely adopted source-pathway-receptor approach to risk assessment and is applicable to any situation where secondary containment may be required. It is standard practice to use recognised standards where they are available and CIRIA 736 is considered the industry standard of choice.

e) CIRIA 736 is a risk based standard which provides a benchmark against which alternatives can be assessed. The key measure of the acceptability of containment taken as a whole is the level of environmental protection achieved. If a combination of primary, secondary and tertiary containment plus any additional measures provides equivalent environmental protection this can be proposed. As the guidance states ‘Where a measure is not suitable or relevant, an operator can either; propose alternative measures, that must achieve the same level of environmental protection or provide an explanation of why the measure is not relevant using a risk based approach.’

Q11 Do you think the guidance is clear on the requirements to cover storage structures?

We received 25 responses:

• yes – 3

• no – 21

• do not know – 1

We received 20 further comments

Summary of responses

a) One trade association noted that ammonia abatement issues will be covered by Defra’s Clean Air Strategy and so should be removed from the guidance. FRfW, Code of Good Agricultural Practice and Silage, Slurry and Agricultural Fuel Oil Regulations were also referenced. They also said that BEIS need to be involved in relation to the Green Gas Support Scheme (GGSS).

b) Some respondents associated the covering of stores solely with the need to control odorous emissions. One trade body responded that members believe that covering storage is difficult and that other solutions can be found in the odour management plan (OMP) meaning that the plant should not need to invest twice.

c) One respondent stated that the guidance should require all vents to be leak tested and must have a have a current leak test certificate. Other respondents felt that requirements on abating and containing vented releases was too prescriptive.

d) Two responders stated that abating emission will conflict with DSEAR regulation where a vessel that could produce methane should not be fully covered.

e) Several respondents added that retrofitting is not appropriate and disproportionately expensive and not suitable for existing assets. Rather this needs to be addressed at the design and planning stage.

f) One water company was seeking clarity on whether this included small day tanks where small qualities are held prior to de-watering. Covering existing tanks will require significant investment and disruption.

g) There was a request to clarify the applicability of cover requirements to storage bays and windrows at open windrow composting sites.

Our response

a) We work closely with Defra and BEIS on emission controls and in particular ammonia. We have worked together on the GGSS, discussed our guidance and have agreed measures that are within our remit to implement through permit controls. It should be noted that the need to control emissions and protect public health is not dependent upon the availability of a subsidy.

b) It was apparent that respondents were unclear whether the purpose of covering storage structures was to abate odour or to prevent other emissions such as ammonia. The guidance refers to preventing or mitigating fugitive emissions including odour, ammonia, methane and other organic compounds and dust. The responses that address only odour ignore the need to control and mitigate other emissions. Odour is a symptom of emission and loss of containment and whilst the OMP covers control of odour and impact on amenity the requirement to cover tanks comes from a need to control and mitigate other polluting emissions. Reliance on the OMP is therefore not sufficient.

c) We have amended the text where appropriate.

d) We liaise closely with the HSE and have sought their advice in the preparation of this guidance. We will follow up comments regarding DSEAR with the HSE and amend the text if necessary. We recognise some of the concerns raised and are also aware that covers can reduce volatilisation and reduce the risk of explosive atmospheres.

e) We have not stated that retrofitting fixed covers is an absolute requirement on existing sites. If retrofitting is technically problematic then alternatives such as a floating cover may be an acceptable means of reducing surface air stripping. This is in agreement with Defra and advice in evidence from various reports, for example Options for Ammonia Mitigation – Guidance from the UNECE Task Force on Reactive Nitrogen.

f) Day tanks are included in this requirement but where appropriate an evidence-based risk assessment could be submitted to propose alternative measures. The comment on cost and disruption is noted but this is not an acceptable reason to disapply appropriate measures.

g) We will amend the text to clarify the requirements.

Q12 Do you think the requirements are clear and helpful to the operator to determine if a bespoke waste is suitable for treatment using a biological process?

We received 25 responses:

• yes – 12

• no – 11

• do not know – 2

We received 15 further comments.

Summary of responses

We received a number of comments about the general applicability of some statements. For example some respondents made general observations about the overly prescriptive nature of the guidance. Others raised concerns about specific requirements such as ‘you must minimise the time you store waste in reception before treatment and hold it for no longer than 5 days’ which was considered to be impractical and dependent on the waste stream as many can be stored for longer without risk.

We accept that there will be exceptions to some of the statements in the document. We are unable to respond to all of them but such instances are already catered for in the guidance which states that ‘where a measure is not suitable or relevant, an operator can either propose alternative measures that achieve the same level of environmental protection or provide an explanation of why the measure is not relevant’. We expect operators to be able to provide evidence of any decisions to deviate from the guidance if asked.

a) One respondent stated that the feedstock for AD plants is variable and the information in the guidance does not provide information about the AD process and plant feedstock.

b) One trade body suggested that requirement for bespoke waste to have a high level of biodegradability is not possible; stating that high lignocellulose waste does not have 90% biodegradability and the stability outlines in PAS 110 should be sufficient. This was also picked up by a water company who stated that waste rarely can be fully mineralised, and asked what equates to full mineralisation, stating that this is an onerous challenge as the lab tests give the degradation rates of the individual waste which may be different when mixed with other wastes. For anaerobic processes full degradation may take 2 weeks to reach full stabilisation, therefore approvals for these wastes will take a minimum of 3 to 4 weeks which is may be impractical for some industries as pre-acceptance procedure. They suggested that in some processes 90% of the degradation occurs in a short space of time with the remaining 10% taking longer. In some cases 90% biodegradability is not demonstrable where partial degradation will have happened in the previous process, before the waste is received. It was suggested that the UWWTD requires a minimum of 80% chemical oxygen demand reduction, however this guidance is even more onerous and may be impractical. Would it be better to align to UWWTD, or just state ‘until stabilised’?

c) Others stated that full mineralisation is impossible but that the recommendations are helpful. However the degree of prescription is excessive and needs to reflect the risk being better captured in the EMS. Others suggested the level of detail required is unclear and illustrative case studies would be appropriate.

d) One water company stated that 90% biodegradability is not demonstrable for some leachates and digestates or centrates where partial degradation will have happened in the previous process, before the waste is received.

So what is the purpose of taking a waste such as a leachate if the biological treatment process it is consigned to does not afford effective treatment?

e) One water company stated that it was not possible to avoid particulate metals in waste and that metals are ubiquitous and it is very challenging to ensure there is no presence of metals. They stated that the sites use 6mm screens, but a number of these waste streams have no other disposal options.

f) One respondent stated they were not sure any labs testing waste have United Kingdom Accreditation Service (UKAS) or monitoring certification scheme (MCERTS) accreditation. Another operator commented that it is not clear how an operator is meant to test and evidence biodegradability. They stated that suitable techniques are not given and believe this should be explained in more detail giving examples of how this can be done. They stated that this potentially is very onerous and costly and questioned if the cost was beneficial. However they did not suggest any other way to ensure the waste was suitable for the process.

g) Several water companies wanted clarification of whether the requirements apply to wastes tankered to the head of a WwTW. One stated that they thought it should only apply to wastes tankered directly into a sludge digester.

h) One water company expressed concern that when receiving sewage sludges from other companies they will have limited control over the bespoke wastes which may have been accepted into the WwTW. They stated that the onus should be on the waste receiver (the UWWTD sites) to characterise and assess the wastes rather than the sewage sludge treatment facility.

i) One respondent commented on the statement ‘if you accept similar waste from a different producer it will require its own pre-acceptance assessment’. They said that they take a risk based approach and have a sampling programme in place, therefore not every import is sampled. They asked whether a ‘season ticket’ style pre-acceptance procedure was sufficient.

Our response

a) Pre-acceptance requires that the characteristics of the waste stream need to be assessed as suitable for the process before agreeing to take the waste. This ensures that an operators meets the permitted waste types and listed activities. Where there is no variation in the waste then a simple annual check on the waste or load delivered can be used. Where there is greater variability the frequency of testing should be increased. Where there are a wide range of feedstocks being received each one needs to be assessed and demonstrated as suitable for the biological treatment it will receive. It is for the operator to consider other variables when making that assessment.

b) The WFD states that the treatment of a waste must be appropriate for that waste. Some wastes sent for biologically treatment have been found not to be capable of biological treatment and are simply being diluted and lost in another bulky waste. This dilute and disperse practice is not acceptable because it is a form of disposal. This is why acceptance criteria are necessary. Waste sent for biological treatment must be capable of being biologically treated, should have high levels of biodegradability, and should not produce problematic breakdown products. We understand that wood and some other plant material takes longer to biodegrade but they are biodegradable. However it is not acceptable for bespoke wastes to go to biological treatment without prior assessment and operators should not be accepting wastes if they are uncertain of their properties. It breaches duty of care requirements and puts both the treatment plant and the output at greater risk.

c) Fully mineralised means that a substance is broken down to its most stable mineral end point. The purpose of demonstrating mineralisation is to show that no intermediate breakdown substances remain within the waste that could have the potential to cause harm. By demonstrating complete mineralisation within the process the operator can show that there are no intermediate substances that could be of concern and therefore a human health risk assessment is unnecessary. The mineralisation test will be retained in the guidance but we will review and revise the text to make it clearer.

d) Leachates vary widely and are often chemically extremely complex. Mineralisation is likely to be of greater concern than biodegradability. A full characterisation of the leachate would be expected. If it can be demonstrated that a high level of mineralisation is achieved then this might justify its acceptance even if the biodegradability of the waste is lower than normally required.

e) The guidance deals with metals in solution not fragments of metals. If there are metal fragments in excess of 6mm there is a problem with the feedstock.

f) There are a number of UKAS accredited laboratories nationally and MCERTS accredited laboratories. Some of these laboratories specialise in biodegradability testing. If the waste producer is unable to provide adequate information the operator should seek the services of a laboratory.

g) Yes these measures apply to wastes deposited at the head of a waste water treatment works. We consider this to be an important control point where it is necessary to ensure only appropriate wastes are entering a biological treatment process. They can only be accepted if it is shown that they are capable of treatment in that process, otherwise contaminants will simply partition into the sludge or the effluent and be released into the environment. We will produce standard rules for tankered wastes deposited at the head of the works. Where operators can comply with these then they will not need a bespoke permit.

h) We agree that responsibility for characterising and assessing wastes received at a WwTW lies with the operator of that facility which is why we apply the pre-assessment and acceptance requirements to imports to the head of works.

i) Yes an appropriate ‘season ticket’ approach should be sufficient if the wastes are similar, well characterised and variability is taken into account. The greater the variability the greater the need for periodic sampling.

Q13 Do you think that the parameters and inhibitory values provided in the section called inhibition values for aerobic and anaerobic processes are appropriate and relevant?

We received 25 responses:

• yes – 3

• no – 12

• do not know – 10

We received 15 further comments.

Summary of responses

a) One trade body felt this was information that had no place in a regulatory document and did not allow for the range of feedstock variability and digester bacterial population.

b) One operator stated that these inhibitory values should be used as guidance only and strict interpretation may prevent materials from being accepted. Another added that it was unclear as to what the inhibition tables add to the document but there must not be an expectation that operators will routinely monitor for these.

c) One respondent stated they were not clear why this is needed and how it is implemented. Another queried if these values are guidance or thresholds.

d) One water company stated the reference needed updating, and more relevant referencing should be used for operational methods. They further commented that by including the specifics of this table, we were not future proofing this document as technology surrounding this changes quickly.

Our response

a) We regulate and control waste inputs through the permits. The acceptance of waste requires the operator to understand its effect on the process and this is about process control, understanding the environmental fate of substances, and ensuring that inappropriate substances are not allowed to enter and compromise the biological treatment process.

b) We developed the original framework for assessing waste as a result of biowaste treatment companies wanting to take various novel chemical and industrial waste streams where the treated outputs were aimed at the agricultural land bank. This was, in the absence of no framework for assessment. Industry was involved in the development of this framework in 2013 to 2014. This allowed a structured assessment of waste streams to guarantee that the resulting outputs where not a risk to the end user or the wider environment. In the absence of such frameworks we would agree a list of waste and the industry would have to adhere to that list or undertake more extensive testing and chemical analysis of the final materials. They are still able to do that if they feel the inhibitory values are not appropriate for their treatment process and can demonstrate this.

c) Where we can be assured that the waste are suitable and fully recovered by a biological process and that biological treatment is a bona fide option then we can agree that the waste can be processed. Where a waste falls outside of the inhibition values it is often possible for the operator to manage this, for example, pH adjustment.

d) We will retain the information in the guidance as it both emphasises the importance of considering inhibitory factors and assists operators in assessing and presenting information on novel waste streams. We will review the literature but would appreciate evidence based comments and examples of where the guidance can be improved.

Q14 Do you think the requirement to install an enclosed flare that is capable of achieving 1,000°C with 0.3 seconds retention time at this temperature should be an appropriate measure?

We received 25 responses:

• yes – 11

• no – 5

• do not know – 9

On the whole this is accepted as best practice. There were 13 further comments.

Summary of comments

a) One respondent said that the requirement to have a flare available always was too onerous. Another said that it was not clear why an open flare is not considered best practice. A third said that they were unsighted on the derivation of this requirement or if it is a reasonable expectation for existing ground flares. They assumed that most or all their existing flares would fail this criterion.

b) One respondent stated that the need for a flare should be based on a site specific risk assessment adding that most AD sites will produce gas from feedstock where non- methane trace elements are readily combustible. Replacing flares will have a significant cost to the AD sector.

c) One respondent stated that the requirement to ‘optimise the flare to make sure the combustion of gases is efficient’ needs further clarification. Another stated that it would be helpful to understand the environmental benefit that is achieved through implementation of this requirement. Methane has a flame temperature of 1500 to 1600 degree C, adding in some endothermy from the CO2 and H2O present in the gas, 1000 degrees C should be achievable in the crescent of the flame. Modifications to the flare to increase either the temperature or the retention time are likely to require flame shaping or repression and this is likely to increase the NOx emissions accordingly.

d) One respondent stated that they thought that this is a desirable long-term outcome and several of their sites are currently compliant. The additional information regarding the intended outcome will allow us to understand the work required at the remainder of our sites. We are happy to upgrade in due course as and when the individual sites are refurbished. However, we see no need to carry out this work prior to that refurbishment and suggest that a derogation of this requirement be granted until such time.

Our response

a) Open or shrouded flares are not permitted in other sectors as there is no capability to monitor the emissions from these types of flares and therefore no assurance that the destruction of volatiles takes place. Flares, whether closed or shrouded (open flares), should be capable of achieving maximum destruction of trace elements.

We believe that all AD plant must have a process and equipment to burn surplus biogas. It is not appropriate to vent biogas to air other than in an emergency.

b) to d) Flares should be able to destroy trace elements and VOCs and the burn time and residence time is critical. Where flares are rarely used then a shrouded flare may be sufficient. It is up to the operator to ensure that maximum destruction is achieved by maintaining the flare and choosing the most effective operating parameters.

Q15 We really value your feedback on the proposed guidance. Please let us know if there are any other sections that are unclear. Let us know how we can improve then. Please provide as much information as possible to support your answer.

We received 22 further responses with multiple technical threads, and we have summarised these. We will take these into consideration and revise the text where appropriate. We will respond to individuals in due course.

a) Section 60 of the draft Appropriate measures for biowaste treatment consultation document requires the operator to consider every option available for managing each waste and material, including extended storage, other recovery or treatment options and disposal. As an operator we would reserve the right to delegate this responsibility to a contractor but understand that the accountability would lie with the operator.

Our response: Contracting out responsibility for delivering contingency measures is risky and we would expect a full audit of any sub-contractors ability to deliver. Ultimately the responsibility remains with the company to demonstrate it has robust contingency arrangements in place.

b) Section 61 on page 42 of the draft Appropriate measures for biowaste treatment consultation document requires an operator to have a system in place to prevent ‘tanker drive off’. It is not clear what systems would be considered acceptable. It is not thought to necessarily be practicable at existing sites either which will have waste reception areas built in a specific way that might not allow this. Significant capital investment may also be required which may not be available until the next Ofwat funding cycle for water companies. Can this be something as simple as an immobiliser fitted to vehicles that detects if it is still coupled?

Page 42 of the draft Appropriate measures for biowaste treatment consultation document – requirement for system to prevent ‘tanker drive off’ (whilst still coupled) – this is impractical for the majority of our discharge points, and we are unsure of a solution.

Other water companies said they can see how this can arise but it did not need to be covered in an appropriate measures document.

Our response: Experience has demonstrated that this can and does happen and because it can have environmental consequences it is included as an appropriate measure. We do not recognise the comment about significant capital investment and the water industry funding cycle is irrelevant. If an immobiliser is effective this would be acceptable. A simple procedure might also suffice such as depositing the vehicle keys by the coupling point which is only released when the vehicle is uncoupled.

c) It is unclear whether some measures apply to interworks sewage sludges and tankered domestic sewage.

Our response: Where activities are excluded from waste controls by the controlled waste regulations then the guidance is not applicable although we believe it is still relevant.

d) The implementation date for low-cost improvements is within 12 months of the document being published. This will be outside the scope to attract WINEP AMP funding. Larger improvements are to be completed as soon as reasonably possible or within the time frame set in the site permit. BAT related improvements need to be completed by August 2022. Both the larger and BAT improvements are outside the timetable for WINEP AMP funding. PR20 has been approved and funding requirements for AMP 8 starting in 2025 will not start until 2024.

Our response: The examples given on page 7 illustrate the difference between low cost and capital intensive. Compliance with legal requirements is not dependent upon water industry funding cycles and any funding issues should be raised with Ofwat.

e) There is lack of alignment to other initiatives such as the Environment Agency sludge strategy and related working groups.

Our response: The review and publication of guidance is not dependent upon delivery of the sludge strategy which is primarily about sludge use and not treatment.

f) Introduces onerous requirements for sites that have not been previously been subject to permit obligations. The retrospective application of BAT to existing assets is too onerous.

Our response: It is not the guidance which introduces BAT requirements to previously unpermitted facilities it is a legislative requirement. Where BAT cannot be achieved at existing sites then the operator can apply for a derogation subject to meeting the strict criteria laid down in legislation. The existing BREF and BAT conclusions set out best practice and it is assumed that most good operators would be operating broadly in compliance with this. Where we feel we need to enhance environmental protection to achieve our own national environment objectives then we can issues further guidance.

g) Sections 3 and 6 Waste acceptance. Would the pre- acceptance and acceptance for monitoring and sampling apply where tankered waste activity is already permitted? Will it be necessary to merge tankered waste permits and biological treatment permits?

Our response: Operators may choose to consolidate these activities under a single permit. This can be more cost effective in terms of subsistence charging.

h) Do operators who only take raw sludge need to adopt the pre acceptance methods? Given that sludge treatment have standards inputs is there a need to assess this annually?

Our response: Facilities receiving only raw sewage sludge for treatment will need to carry out periodic checks on quality but if the waste is well characterised and consistent this can be done less frequently. Raw sewage delivered to the head of works is excluded from waste controls but some basic analysis is advisable to manage the load on the works.

i) One water company suggested that managing bulk loads and tankers where sites are unmanned or out of hours was too onerous.

Our response: We are surprised to learn of unmanned sites, but some controls would be necessary, and the company should submit their risk assessment and procedures. Where works are unmanned (highly unlikely at permitted facilities) CCTV and remote monitoring are already mentioned in the guidance as an option.

j) Where there is a dedicated fleet of tanker who only carry raw sewage sludge will a wash out certificate be necessary

Our response: No it will not be necessary to have wash-out certificates if the waste is the same and carried by a dedicated fleet of vehicles. We will clarify this in the text.

k) The use of meteorological monitoring will be overly expensive for the water industry and sludge treatment continues all year round.

Our response: The use of weather data and monitoring does not have to be expensive and can be easily recorded on site. The operations can be timed or adjusted to comply with conditions. This is especially important where the operator intends to moderate operations when the prevailing wind direction is towards a sensitive receptor.

l) There has been no assessment of the impact on regulated business and would be expected when regulation is changed.

Our response: We have not changed regulation. We are updating existing guidance on appropriate measures. However, we are required to do a business impact target assessment.

m) Proposals for plant enclosure conflicts with health and safety requirements and have not been fully considered

Our response: We have not stated that existing sites need to be enclosed. We have shared these documents and worked closely with the HSE over the past years about concerns we share about the sector.

n) One water company stated that these obligations were not indicated or foreseen prior to the recent business planning cycle and funding is not provided to meet these obligations. This is true for all the required explicit and implicit improvements indicated but is an obvious obstacle for containment, enclosure and fugitive emission expectations in particular - ‘softer’ requirements such as competence and training will be challenging to be met within the year of adoption of this guidance.

Our response: It would be concerning if there was a significant shortfall in competence at existing water industry facilities. Staff competence and training have long been recognised as standard best practice and company training and competency structures should already be in place. These can be developed into a corporate competence management system or used to deliver training for the necessary modules under the waste management industry training and advisory board scheme.

o) One water company commented on the absence of any reference to the SUiAR, the safe sludge matrix or the biosolids assurance scheme (BAS) is surprising as the water sector largely deploys anaerobic digestion to satisfy these expectations.

Our response: These are out of scope for the treatment guidance. SUiAR and the safe sludge matrix relate to the storage and use of biosolids. BAS is an industry standard with no regulatory role.

p) Removal of plastics is impossible for sewage sludge.

Our response: We acknowledge that microplastic in sludge is an issue and extremely difficult to remove. Larger fragments of plastic and other litter are usually removed by screening. Further work on microplastics in the environment will inform future policy and regulation.

q) Grit removal is a particular issue for operation of sewage sludge digesters and must not be mandated.

Our response: We will amend the text to clarify but it is important that the integrity of mixing systems and primary tanks assessment is set out in procedures. As with all measures if it is not relevant to certain facilities then the operator is free to demonstrate this is so.

r) Grit and sediment removal from PAS110 containing vessels - if the vessel is only ever containing ‘product’ where does the ‘waste’ aspect materialise from and why should waste controls be placed on the grits and sediments that could have otherwise been removed in the digestate. One member has expressed concern at this as they undertook PAS 110 to be exempt from waste regulation controls and may still be held to them after conforming to PAS 110.

Our response: If grits and sediments are being removed from the vessel that produces PAS110 digestate they are not digestates and cannot achieve end of waste status. They are regulated as a waste.

s) The proposed expectations for methane slippage is a particular if relatively minor concern, as this sets an unachievable expectation where gas engines are involved. As such it should be deleted or revised, as this appears to be out with operator control, with no commercially viable or readily available abatement solution possible.

Our response: We have been monitoring the emissions data and we are aware that methane slippage may be a significant issue. This is a guidance document but we are undertaking review of emission monitoring and will review that data to assess if in future secondary abatement needs to be instigated. Methane slip is detrimental to the environment and is a loss of income to operators where the combustion is not efficient.

t) The presumption of enclosure for receipt of sludge cake will drive unnecessary and unfunded expenditure. It would potentially create new confined spaces or DSEAR areas and so is inherently undesirable, not likely to be cost beneficial and so should be removed.

Our response: The requirement to enclose reception areas for sludge cake will not be taken forward. We will expect operators to take other operational measures to minimise emissions from the handling and storage of sludge cake.

u) Regarding the need to calibrate meteorological monitoring equipment every 4 months. This will depend on the type of instrument used and there is little benefit to prescribe such frequency

Our response: It is an appropriate requirement given that meteorological conditions are a material consideration for on-site operations. The absence of a frequency would cause the requirement to be unenforceable and the 4 month figure is caveated by words ‘unless agreed otherwise with the Environment Agency’ so it is flexible.

There were additionally many hundreds of individual comments and we have taken these into account and revised the guidance where appropriate. We will endeavour to feed back to individual responders in due course where requested.

6. Next steps

Now we have considered the consultation responses received, we will finalise the guidance document for publication. We will publish the finalised guidance on GOV.UK.

We will convert the PDF document that was used for the consultation to HTML format so that the guidance is fully accessible.

7. Annex: list of consultation respondents (by name)

The organisations that responded are:

• Veolia
• Assentech Sales Ltd
• Yorwaste Limited
• Charlie Trousdell Associates Ltd
• Aqua Enviro, a UK subsidiary of SUEZ Smart and Environmental Solutions
• Environmental Services Association (ESA)
• REA - The Association for Renewable Energy and Clean Technology.
• Foodchain and Biomass Renewables Association FABRA UK
• Biffa Waste Services Limited
• Yorkshire Water
• Andigestion Ltd
• Wessex Water Services Ltd
• Natural World Products Ltd
• The National Farmers’ Union (NFU)
• Viridor Limited
• Thames Water Utilities Limited
• Bio-Based and Biodegradable Industries Association
• Chartered Institution of Wastes Management (CIWM)
• Severn Trent Water Ltd
• United Utilities
• Anglian Water Services Ltd
• The Anaerobic Digestion and Bioresources Association (ADBA)