Recorded webinar
Understanding CIRIA C736: What Regulators Expect from Your Containment Systems
18 June 2025
Operators of Food and Drink facilities are under growing pressure from regulators (the EA, NWR, SEPA) to demonstrate compliance with best practice for secondary containment of liquid stores.
Best practice guidance is contained within the document CIRIA C736 - ‘Containment systems for the prevention of pollution: Secondary, tertiary and other measures for industrial and commercial premises’.
The document provides guidance on identifying hazards and mitigating the potential consequences of a failure of the primary storage facility and/or the combustion of its contents.
As lead authors of the document, SLR will explain the content and implications of the guide for operators, and help you understand how to meet regulatory expectations with confidence.For any more information - please contact Danny Jones.
Topics
SLR - Understanding CIRIA C736: What Regulators Expect from Your Containment Systems
SLR - Understanding CIRIA C736: What Regulators Expect from Your Containment Systems
0:04
Good morning, everyone, and welcome to today's webinar, which is on understanding Syria C736, hosted by our professional affiliate members, SLR.
0:14
First of all, thank you to everyone for coming today. We hope that you found the content useful.
0:18
There will be a Q &A at the end of the session, so please put any questions that you have into the questions box, and we'll do our best to go through as many as we can at the end of the webinar.
0:27
Following today's session, we'll be sending you an article email in the next couple of working days, and this contain a recording of the webinar, a copy of the slides, and the contact details of the presentation presenter. So, without any further ado, I'll hand you over to the presentation presenter, Danny Jones.
0:42
Hello, good morning, everyone.
0:44
So, yeah, this is Siri SC 736, which is all about good practice for secondary containment of potentially polluting liquids.
0:56
If I just start off with a quick introduction. So, I'm Danny Jones. I'm a technical director in SLR.
1:04
I come from the waste management industry.
1:08
My interest in secondary containment largely revolved originally around containment of liquid wastes emanate from landfills and I ended up writing a industry code of practice relating to the storage of leachatus, it's known.
1:27
I work closely with my colleague Ian Walton, for those of you who have your own copy already of C736, you may have noticed his name at the front, he was the lead author in producing the Syriac guide.
1:45
So to leap straight in, legal background to the issue of secondary containment.
1:53
Under UK law, it's an offence anyone to cause pollution.
1:56
Whether you're a private individual or a commercial organisation, anyone who allows the environment to be contaminated by polluting materials is committing an offence.
2:05
This is enshrined in UK law and the Environmental Protection Act, the Environment Act and environmental damage regulations amongst other pieces of legislation.
2:18
Major accident hazards, so events or scenarios that occur outside of intended operations.
2:25
They also cause significant risk to the environment.
2:28
These risks should be proactively controlled if you fall under the coma eggs.
2:32
I'm guessing in the food and drink sector, few of you do fall under coma, but it is something to think about.
2:40
Operators of facilities that are considered to pose a higher risk of pollution are captured by the environmental permitting England and Wales regs or the pollution prevention and control regs in Northern Ireland, environmental authorisations in Scotland.
2:58
These regulations require operators to obtain a permit effectively from the relevant authority, so the EA in England, NRWA or NIA in Northern Ireland, SIPA in Scotland, that will contain details of how the regulator expects the operator to provide suitable protection against causing pollution and that includes from loss of contaminating liquids from their sites.
3:22
For sites that are permitted, the regulator can use the permit as a means to enforce the provision of suitable secondary containment.
3:32
However, regardless of the permitting status of a plant, everyone's required to not cause pollution and if we do and are prosecuted, whether we take count of best practice will be a consideration of the court when passing a sentence.
3:48
So while some small operators may choose not to follow best practice, assuming they're never going to cause a pollution incident, if you do and you do end up in court, it is a factor that will be considered when sentencing should you be found guilty. The law and good practice.
4:08
So Acts of Parliament and their subordinate regulations of the law.
4:12
Regulations published endorse good practice or guidance.
4:17
So that's a description of how operators are expected to comply with the law.
4:21
These guidance documents are not necessarily considered to be statutory guidance and so they're not the law in and of themselves.
4:28
The failure to comply with guidance can, as I said before, be used when sentencing should you be found guilty of causing pollution.
4:38
In terms of the provision and maintenance of adequate secondary containment infrastructure, guidance is contained within Sirius C736 Containment Systems Prevention of Pollution.
4:53
This was published in 2014 and is considered to be best available techniques for new build facilities and relevant good practice for existing facilities.
5:04
There's also some additional industry specific guidance out there, which should also be referred to as an example, there are the pollution prevention guidelines for above ground oil storage, there's HSE guidance on storage of flammable liquids, for example, and say there's an eye cop in the landfill industry for storage of leachate.
5:30
Failure to maintain adequate containment can lead to regulator intervention and prosecution should pollution occur.
5:44
So, Syria C736 published as a major update to the Syria 164, which was design of containment systems for prevention of water pollution.
5:57
It was updated largely after the Bontz Field incident in, but contrary to some people's understanding of C736, that doesn't mean that the guidance is limited to the oil and chemical industries. It applies to every industry effectively.
6:16
The purpose of the update was to move from a generally prescriptive approach in C164 to a more risk-based approach in C736.
6:31
Anyone storing potentially polluting liquids, which is more properly called inventory in the guidance, is caught by the guide that ranges for anything from lightly contaminated water through to the most polluting of man-made persistent chemicals.
6:51
The guide was funded by the EA and SEPA and you can expect them to use it when regulating you.
7:01
The purpose of the publication was to reduce the risk of harm to the environment through the proper storage of inventory principally by addressing the risks to ground and surface water.
7:12
This guidance generally looks to reduce rather completely eliminate risk by undertaking risk assessments that balance potential harm against resources required to remove the risk, so measures that are proportional to the risk.
7:27
The guide provides guidance on the design and construction of new secondary and tertiary containment systems and also the inspection, maintenance, repair, extension and upgrading for any existing installations.
7:44
The 736 guide is based around a risk assessment approach which uses a source pathway receptor model before establishing site risk ratings for a storage facility.
7:58
Depending on the site risk rating, different types or classes of secondary containment are defined.
8:04
In the risk assessment sources, which is the contents of tanks, or more properly called inventory, remain fixed, as do the receptors, so the ground, ground water, surface waters, which are usually defined with reference to regulated classifications of these features.
8:23
It's the pathway that containment seeks to break, and this can be affected by good engineering and good operational practice.
8:31
They can get less likely that spill of inventory can actually find its way from the primary storage vessels out to the receptors.
8:43
Primary containment.
8:44
So C736 focuses on the engineering and operation of secondary and tertiary containment systems and it isn't intended to provide any guidance on primary storage vessels.
8:55
There is other guidance in existence in relation to providing suitable primary storage vessels.
9:02
So there are British standards, so BSEN 13445 for instance talks guidance on pressure vessels, it's a similar guidance for GRP plastic vessels and tanks.
9:15
There is guidance on atmospheric storage tanks, there's the ASME guides on different types of work and there's BSEN 14847 etc. that deal with pumps and pumping infrastructure.
9:31
Should be remembered the primary storage can include everything from packaging in which liquids are purchased, transported and stored on site ranging everything from drums, barrels, IBCs, proprietary tanks, custom designed vessels, and lagoons, through to more complex structures and facilities that contain the liquid, which can include whole facilities.
9:59
So, pipes, pumps, your manufacturing vessels, if they contain potentially polluting liquids, are all classed as a primary containment and all need to be considered when designing or defining your secondary and tertiary containment measures.
10:19
Before moving on, probably best to start with some simple definitions to make sure we all understand the various elements that are involved in a C736 assessment. So firstly is primary storage.
10:33
So the most important means preventing major incidents involving loss of inventory.
10:38
The primary storage is the equipment that has direct contact with the inventory, whether it's being stored, transferred or manufactured.
10:46
It includes infrastructure such as tanks, IBCs, drums, pipework, valves and pumps, as well as associated management and control systems, and can also include whole structures such as buildings that contain liquids. Pathways.
11:04
This is the means by which, without secondary containment being in place, inventory would find its way to the receptor.
11:09
This is often overland flow is a very common means of pathway, although liquids can also leak through underlying grounds and the geology and the soils beneath the ground are all pathways, but also through commonly other site services such as sewers and drainage systems and ducting.
11:32
If you lose your inventory into site roads, site drainage systems, they will ultimately discharge somewhere off site, whether that be into roadway, public highway drainage or into local streams and ditches.
11:49
You then have the receptors, so there is an element of human or natural environment that could be adversely affected by the source of contamination, and it includes the ground, surface waters, ground waters and any relevant sites of special scientific interest, those kinds of nature reserve issues are all considered to be potential receptors.
12:14
You then have secondary containment. This can be local or remote.
12:20
It's usually an engineered means by which the pathway to the receptor is disrupted.
12:26
Secondary containment minimises the consequences of a failure of the primary storage by preventing the uncontrolled spread the inventory.
12:34
Secondary containment is achieved by equipment that's external to and independent from the primary storage, most typically concrete or earth bums surrounding tanks.
12:46
But it can also be things such as walls as a warehouse storing drums.
12:52
Secondary containment can however also be remote.
12:56
So it can be a separate set of funds or tanks distant from the primary store with a means of transporting a spill from the primary containment area to the remote secondary containment tank.
13:14
You've then got what's called tertiary containment.
13:16
So this is further containment measures that minimise the consequences of a failure in the primary and secondary containment systems.
13:24
This provides an additional layer of protection in an event that causes the escape of liquids from the containment through failure or overflow.
13:34
So for instance, a jetting failure that overwhelms a bund can be ameliorated by there being tertiary containment.
13:43
This is often remote from the point of primary tanks and it's often kind of co-opted areas of roadway, hard standing, loading bays, that kind of feature surrounding an industrial facility.
14:03
And finally we have transfer systems, so these are the means by which you can reliably move spilt material from the point of spill to its storage location.
14:16
This can be pumped and systems it can be design of roadways and spillways to transfer liquids to a particular location.
14:31
Syria encourages the use of local secondary containment rather than remote secondary containment because it's entirely passive and doesn't rely on other systems working properly at all times to liquid.
14:47
So whilst transfer systems and remote secondary containment and remote tertiary containment are all possible within Syria, when you start relying on those types of systems you have to put much more thought into things such as how do I ensure pumps are working at all times, have pipe work been designed to accommodate flows that are likely from a primary failure scenario, are drains kept clear and free flowing?
15:14
Are there any bottlenecks or pinch points in the system?
15:22
The C736 guide is split into three main parts.
15:25
Part one is essentially how to risk assess your site, determine the class of bonding needed, and how to assess the required capacity of the containment needed.
15:35
This detail needs to be understood for a site, whether you are assessing an existing or designing a new system of containment.
15:43
Part two details how to assess existing containment systems, part three discusses design details of new build containment systems and how to repair and upgrade existing systems.
15:59
So a few key concepts within containment classification.
16:05
736 is a risk assessment that should be carried out to determine what type of bund is needed and how it should be designed.
16:12
It provides guidance on the design and construction of new and secondary containment systems and on the inspection, maintenance and repair extensions and upgrading of existing.
16:22
You use source, pathway and receptor model and you assign them high, medium or low ratings is then combined together to produce a site hazard rating.
16:39
The site hazard rating is combined with a likelihood of loss of containment to produce a site risk rating.
16:47
It ultimately ends up in a high, medium or low score for a site.
16:53
That leads on to your classification, so a low score gives you a class one type of bund and a high score gives you a class three.
17:03
Thereafter, Syria requires designers to consider and justify on a risk-assessed basis other features of the containment system design that are intended to ensure inventory does not escape from containment.
17:16
For most plants, Class 2 containment is what you would typically expect. I rarely see Class 1 and I rarely see Class 3.
17:27
Class 3 you're getting into kind you know, major stores of bulk chemicals, hydrocarbons, that kind of thing in very large volumes.
17:39
Class 1, lightly contaminated waters.
17:43
Class 2 covers most of the inventory that we see at most sites. So bun classes, the main output of the assessment is the bun class.
18:01
Class I buns, low hazard, acceptable for very lowest hazard, small volumes and or very lightly contaminated liquids in low risk settings.
18:11
So, for example, good primary containment with high levels of control to prevent over topping, lots of design redundancy, few low velocity pathways to few or low sensitivity receptors would result in a Class I bun.
18:27
Class two is the medium hazard, most common type. So more industrial volumes of liquid in storage, typically more than a few cubic meters.
18:40
Contaminated liquids in medium risk settings.
18:43
So, you know, maybe good primary containment, some control of overtopping, bit of design redundancy, locations with a variety of pathways, some of which are faster than others, and a variety of sometimes sensitive receptors.
19:00
That's three, obviously the higher hazards, higher volumes, or lower hazard and lower volume storage in very high sensitivity locations.
19:11
High sensitivity locations would be groundwater protection zones, protected habitats surrounding the site, sites that are within flood zones of a high risk.
19:23
Once the bund class has been defined, you then need to consider other design factors to run through them at high level.
19:31
So the layout, so proximity of tanks to bund walls, for example, to prevent jetting and to prevent tank collapse, also damaging the secondary containment facility.
19:46
Materials of construction, So for instance, block work is only permitted in class one containment.
19:54
If you're a class two and three, block work isn't an appropriate bund wall construction material.
20:04
Bund drainage, so gravity drainage out of a bund is not permitted in class two and three bunds, should always be pumped.
20:11
And this is to prevent any spills and leaks just automatically being discharged out the bun on the assumption it's clean surface water.
20:24
There's other detailing involved when you get into the detail of Syria, when you look at the design requirements for, say, concrete buns in class two and three, there are requirements for water bars and kicker joints to be included and for construction to be in conformance with a particular design code EN1992-32006 so that's a liquid containing and retaining concrete structure with all kinds of design details looking at control of crack width etc, essentially making sure that the concrete is truly water retaining.
21:06
Leak detection is required for earthwork bunds, below ground bunds and class 3 bunds.
21:20
The only look at the volume of containment is one of the most significant things that you need to look at when designing a bund.
21:28
Historically everyone has focused on the old traditional 110 or 25% rule of thumb, So, bonds need to be 110% of the largest tank stored within them, or 25% of the total volume of tanks within a single bond, whichever of those two figures is greatest.
21:51
Syria asks you to think further than that.
21:54
You need to think about containment of an adequate amount of rainfall.
22:02
You also need to think about containment of fire water.
22:06
So generally the extra 10% and 110% rule is supposed to cover containing fire water, firefighting agents such as foam and rainfall.
22:17
but this only really works if you're in an average rainfall area or if you aren't holding any flammable liquids as your inventory.
22:30
The extra 10% in the 110% rule is unlikely to contain fire water and cooling water if the inventory itself is flammable.
22:40
So, Syria asks you to look specifically at rainfall and firefighting water.
22:53
As a minimum, you should think about 100% of the primary storage volume for a single tank.
22:57
And for multiple tanks, you should think about credible failure scenarios.
23:01
So if you're storing flammable liquids, there's a much higher chance of a pool fire developing, and therefore all tanks within a bund failing simultaneously.
23:13
And if you're storing flammable liquids that's a scenario that you should consider.
23:19
Generally you should consider the brimful capacity of any primary tank, not the nominal or tank rated capacity.
23:27
It is possible to make an argument for these lower capacities to be used, but in principle, Syria is expecting the brimful capacity of the tank to be used.
23:36
You need to make your allowance for rainfall to accumulate if the bund is open to rainfall, i.e. not roofed.
23:45
Syria asks you to think about 24-hour in the build-up to a loss of containment event, the duration of the loss of containment event, and then a likely duration for a clean-up thereafter.
23:59
This can be as much as 10 days, is recommended in the Syria guide, unless you have some strong reason for foreshortening that period of rainfall accumulation.
24:11
Syria also asks you to make your firefighting water allowance if your inventory is flammable.
24:21
All of this information is included in the Syria guide and some examples are given and some general guidance in terms of rainfall usage.
24:28
But what Syria is asking you to look at is to use a flood estimation handbook and use 10% AEP or annual exceedance probability rainfall events.
24:39
So what it's asking you to do is look at something like an 8 to 10 day rainfall period in the heaviest rainfall event you will likely get in a 10 year period as the amount of rainfall that needs to be held within your bond as well as your lost infantry volume.
25:03
Bond volume calculation should also consider the need for freeboard and accommodating the firefighting waters. So freeboard.
25:10
Has sufficient freeboard been allowed to account for uncertainty?
25:14
Where flammable liquids are stored or where material in the vicinity of the stored material is flammable, for example building stored storing materials at an AD pant, for example, that may be flammable.
25:27
Has at least 100 mil of freeboard been allowed.
25:31
Have dynamic effects such as surge from catastrophic failures, wave action, et cetera, be considered as part of the scenario?
25:39
If they haven't been specifically modeled and defined in terms of how much freeboard is needed, Syria suggests that you should sided lagoon, it suggests 750 mil of freeboard is required on top of any volume requirement calculated from inventory loss and rainfall allowance.
26:14
Again, on top of that, if you have any flammable liquids in storage, you then get into a different world of calculating firefighting and cooling waters.
26:30
There are several different methods for doing this laid out within the Syria guide and there are several methods of making estimates but it doesn't actually specify which method to use and in all cases the answer is several thousands of cubic metres of firefighting water is likely to be required.
26:56
This is often not economic to provide in terms of local secondary containment and this is where you might want to start thinking about remote secondary containment or tertiary containment systems.
27:07
What is also useful to do if you're storing flammable liquids is to speak to your local fire department, fire and rescue services and they will be able to provide you with advice on how much water or other firefighting agents, they believe they would apply to a particular emergency incident at your facility.
27:29
However, it's worth noting that failure to manage firefighting waters is one of the principal causes of environmental harm from facilities.
27:39
It's often the case that when facilities catch a light, it's the runoff from the firefighting activities that delivers the pollutant into the environment.
27:52
So just mentioned tertiary containment.
27:54
It's often a solution for scenarios where it's impractical for secondary containment to realistically contain some of the more extreme, less likely failure, less likely failure scenarios including firefighting.
28:07
It's also used where jetting from over the secondary containment is possible or to mitigate deficiencies in any secondary containment.
28:15
Typically this includes overwhelming of secondary containment due to surge effects from catastrophic collapse scenarios, overfilling from firefighting activities and significant spills from activities such as tankering of large volumes of inventory in or out of primary containment.
28:34
For flammable inventory, it's generally uneconomic to design the application of firefighting water due to uncertain and potentially high volumes.
28:44
Therefore, reliance is often placed the tertiary containment.
28:47
Tertiary containment can be developed out of pre-existing facilities such as hard-standing areas like roadways, service yards, car parks or underground tanks associated with site drainage at the facility.
29:02
Through the use of infrastructure such as raised curbs, ramps to allow ingress and egress of vehicles whilst providing containment across vehicle or pedestrian access points, valves or other devices to close off site drainage and floodgates, additional storage can be provided in facilities such as purpose built tertiary containment surrounding bundling facilities or in extreme circumstances by using temporary barriers to create storage areas in car parks, service yards or roadways.
29:36
Consideration should be given to where any entry that escapes primary and secondary containment will go to when it's soaking to the ground, when it run off over land, will it drain to surface water, sewers or soakaways?
29:50
If you're going to use tertiary containment, how is it going to be mobilised? Automated closure valves installed on drainage outfalls.
29:59
Can containment be improved by enhancing existing curbing on roads, hard standings and parking areas? Can sacrificial areas be identified and used to store liquids?
30:10
Temporary and emergency containment and spills responses also need to be considered and can include temporary bundles, booms, tankering, spill kits, these kinds of things.
30:21
But I would want to emphasise that in principle, Syria discourages the use of these kinds of mechanical or human-operated devices to create containment because there is a much higher likelihood of failure or misoperation of these types of devices.
30:39
If possible, you should be providing containment through entirely passive means.
30:50
Existing facilities is a fairly major problem so much attention is given to bonding around during site design and construction phases.
30:58
However, a significant part of the C736 guide relates to existing facilities where you may already have containment.
31:06
Relatively few new facilities that require secondary containment being constructed as opposed to existing facilities where secondary containment is being considered for retrofitting.
31:21
SLR's experience is that assessment, inspection and maintenance of existing infrastructure is often the poor cousin when compared to the more exciting process of designing a new bund.
31:31
Extensions, modifications or updates to existing containment is much more common.
31:38
Often this work is driven by the regulator as an add-on to other modifications taking place at a facility.
31:44
For example, the operator wishes to add another process or extend the capacity of a facility.
31:51
As part of the permitting process for this, the regulator add on an improvement condition or pre-op condition to assess the existing containment against good practice and they will usually reference Seria C736.
32:07
SLR's experience of undertaking inspections of existing bunding arrangements indicates that typical problems encountered a lack of knowledge of the actual construction details of existing bunds, so lack of record stating what was actually built, poor compliance with good practice recommendations, and most particularly, a lack of formal and recorded bund inspection records.
32:32
To make an assessment of an existing bund, you follow essentially the same processes for a new build bund. So you do a source pathway receptor, give your bund a classification.
32:42
You then would undertake a gap analysis against what you've got versus what Siria recommends you should have.
32:50
And it's the duty holder, so the site operator's responsibility that facility presents an appropriate level of risk to the environment.
33:01
Containment systems should be regularly reviewed and inspected to ensure that they remain fit for purpose and particularly whenever there is a change to the inventory stored or less likely scenario that pathways or receptors change in nature.
33:20
Serial guides does not require that all historical facilities get re-engineered to meet modern standards, but instead incorporates the concept of a LARP, so it's low as reasonably practical, but existing facilities must demonstrate that the risk that they posed is as low as reasonably practical and relevant good practice should be adhered to.
33:47
When assessing existing facilities, the focus of 736 guidance is on accessing three main areas. The difference between best practice and what you actually have on site.
33:57
So why is what you have different, say, to a cast in situ concrete wall?
34:04
It's incumbent on the duty holder to seek professional advice when necessary to make a proper assessment and it's not acceptable to rely on a have-a-go maintenance staff or local builder, for example, when you're assessing the adequacy of your bundling under Serious E736, anyone undertaking the assessment or doing any kind of an inspection has to be able to demonstrate that they're suitably qualified and experienced. The next thing is how impermeable is the bund that you've got?
34:36
So joints, if you've got a concrete bund, does it have water bars that are fit for purpose?
34:41
Were they properly installed? How do you know what's in place?
34:44
what was the actual design and construction of your bund.
34:49
Penetrations.
34:51
These should be avoided wherever possible in a bund but if they're not possible to avoid then there are details around how any pipe penetration through a bund wall is being installed that you would need to be able to demonstrate and show that it performs an impermeable and suitably robust joint to the bund.
35:11
If you've got earthwork Buns, you will need to be able to demonstrate that the earthworks are indeed impermeable.
35:22
This may result in you having to investigate the permeability of buns, compaction of soils, robustness of the structure etc. to justify their ongoing use.
35:34
Lining systems, so these may be required for Class 2 and 3 buns, particularly where you have soil bunds you may need a membrane liner over the top of it and again these will need to be proven to be watertight and that will need to be done on a periodic basis as they can deteriorate over time.
35:53
Fire resistance, again if you have flammable liquids in storage you will need to prove that your containment system is suitably resistant to the effects of heat and fire.
36:04
Again this comes down things like joints and penetrations and water barring.
36:13
These were elements that failed during the Buncefield fire and that's how the fire spread was things like water bars were plastic and during the fire that followed the initial leaks at Buncefield a lot of these features melted in the fire and it was seen that so for instance metal water bars performed obviously much better plastic ones.
36:40
To find out more detail on works that should be undertaken on an existing facility, firstly a periodic assessment, in some cases this may in fact be the first assessment of the source pathway receptor model should be undertaken as discussed previously.
36:55
Thereafter you should undertake a baseline asset survey, this should be undertaken by a suitably competent person, no formal definition of this but typically it's somebody who can demonstrate experience in the Syria guide or suitably qualified civil or structural engineer.
37:14
The assessment should consider the volume of inventory that you have and how this is defined.
37:19
So is it working from brimful, operational working volumes, etc.
37:24
The type and volume of containment.
37:28
The volume needs to include the total volume and the usable volume.
37:31
So you need to be removing any structures that are occupying volume within your bund from your calculations of usable bund volume.
37:44
What is known about the bund? What's its shape? What's its construction? What are its dimensions?
37:49
How much free board does it have? Does it include anything like defectors to accommodate surge etc?
37:55
If surge is a credible failure scenario, what type of construction was it?
38:01
If an earthen bund, what type of permeability is achieved?
38:05
Are there any protection from erosion, how thick are soils, etc. If it's concrete, is it reinforced, was it cast in situ, was it pre-cast?
38:14
Are there any potential leakage pathways? As part of the design of the bund, are there joints, drainage, penetrations, etc.
38:23
Over time, have any of these features degraded so that they're no longer watertight?
38:27
Cracks or other failures developed in the structure of the bund.
38:30
So, for instance, have any plants begun to root in the bund and are they affecting its permeability?
38:37
These surveys may highlight that further information is required about the bund.
38:42
It's not possible to derive from existing information and you therefore may need to have some additional investigations.
38:50
Investigations to establish type of construction.
38:53
So you could take calls from bonds and determine the presence or absence of reinforcement bar, for example.
39:01
investigations and calculations to establish the bund's stability and ability to withstand static and dynamic loads, investigations into the bund's ability to resist fire, type and detail adjoining.
39:19
We often find, however, that the cost of these investigations often outweighs the cost of just simply rebuilding your bund but obviously that's a very site specific choice to make.
39:35
Once the survey has been completed you then do your gap analysis against the Syria guide, compare the bund class, identify measures required to bring the facility up to the required class so maybe you're repairing or upgrading parts of the bund or providing additional tertiary containment.
39:52
It's always important to discuss with the regulator to sure that you are not about to invest in a solution that will not get approval from them.
40:01
And again, you need to be reducing risk to satisfy the law.
40:08
Note that it's not the intention of the guidance blanket retrospective application.
40:12
There is the ALARP concept within the guidance that applies to existing bonds.
40:21
And however, if you're reliant on that argument, you should expect the regulator to come back to you and actually prove on a cost benefit analysis that further improvements are not justifiable.
40:36
And there are cost benefit analysis tools that can be used to establish whether the cost of the measure is reasonably practical or grossly disproportionate versus the benefit it would provide.
40:50
To demonstrate that you're with good practice, even with bundling that doesn't and cannot economically be made to be compliant with current standards, you must be following the relevant good practice in the Syria Guide.
41:04
So that is to inspect and maintain bundling and keep under review the risks that are proposed by the facility from loss of containment.
41:13
Whether practical and possible to do so, non-compliant elements of the bund design should be brought up as close as to current standards so as to reduce the risks.
41:24
Maintenance and inspection is essential for all existing containment systems and ensure that they continue to provide the maximum protection possible.
41:36
Good practice is to have maintenance plans and inspection regimes in place and to note that there's no specific guidance on how frequently and what kind of plans those are in the guidance other than the fact that you should be doing them on a regular basis.
41:52
Maintenance inspection regimes.
41:57
The guide includes daily advice that you should be doing daily inspections from operational staff, weekly inspections, always after rainfall to check that water is being removed from the bund.
42:12
There are then suggestions that a Works Engineer or Simmer suitably qualified manager should be undertaking annual inspection, pipe work, loading basics etc.
42:26
and this should be more detailed than the daily and weekly as you're looking for cracks, corrosion, damage, whether the site is still maintains its integrity, looking at things like signage and other equipment related to the bund, is it all still working? Can you prove that it all still works?
42:44
This should all be linked to a maintenance plan and you should be able to demonstrate that you're doing these inspections and acting on the observations of the inspections and putting things right.
43:00
Every five years you should be considering completely renewing your Syria assessment and you should certainly do it should you change the inventory that's being stored and you just again run through the same process as we've just described source pathway receptor model review any inspections previously carried out review the maintenance that's been carried out needs to be done by a suitably qualified assessor 10 yearly so less frequently you should be thinking about things like wall thickness and NDT testing if your bundles are made of metal and surface inspections by qualified inspectors, perhaps undertaking leak detection, those kinds of tests. So not every process is included under Syria.
43:56
The front of Syria includes some exclusions the things it doesn't deal with, a primary containment, it doesn't deal with underground storage tanks, it doesn't deal with offshore installations, it doesn't deal with the off-site activities, so you are expected to deal with the loading and offloading of a tanker while it is on your site, but you're not dealing with its activities when out on the public highway.
44:27
Some of the big exclusions are sewage and sewage effluent, but I don't think that will apply to most of your facilities.
44:42
However, other than water, most stored liquids are included.
44:48
So just because you might be storing food and drink doesn't mean there's no risk from a catastrophic release of these materials to the environment.
44:55
It's often considered that if you, for instance, have concrete tanks that you don't need to use Syria because there's no chance of failure of a concrete tank.
45:06
That just simply isn't true.
45:07
There is a chance of failure.
45:09
Syria does cover it.
45:11
You also have to think about things like failure of fittings of pipes entering and exiting tanks.
45:18
So there is always the chance that your tank will fail in some way, shape or form and therefore all types of tanks are covered by Styria.
45:29
As an example of that, if you consider you've got something like a 130-150 cube tank made of a very robust material but you've got a 250 mil diameter pipe or valve in its base and that gets accidentally opened or knocked off, the entire tank will empty in less than 15 minutes it will be emptying at a rate of approaching half a cubic meter a second initially.
46:01
Such an event will end up with a jet out of that open aperture that can extend for four to five meters from the base of the tank.
46:12
It's also worth considering that what are considered be dry systems that take place outdoors and can be rained on they will also produce a contaminating effluent that is also covered by this guidance so if you're storing dry materials they get rained on it gets into drainage you will need to consider the secondary containment of that draining potentially polluted liquid.
46:38
The guidance does consider use of lagoons but only as secondary containment vessels, it doesn't, like every other vessel, it doesn't consider them as primary storage vessels. What should be included in a good serial assessment?
46:55
So first of all, all serial assessments should state who has completed the assessment and their competency. Every serial assessment should include a source pathway receptor model.
47:07
You must go through that process and you must define your BUN classification.
47:15
All tanks and vessels, even in production areas, need to be considered as sources.
47:22
When you're defining the source, you're looking at the volume of the liquid, its quality and the resultant pollutant risk, and you'll be assigning a high, medium or low rating.
47:34
Note that if a tank or lagoon normally has volume stored in it, only the unused volume can be counted as containment volume.
47:42
So this is an issue where you have, say, a storage tank related to an effluent treatment plant that serves your primary production facility, it's often tempting to say the effluent storage plant's inlet tank is the secondary containment volume for our primary tanks in our production facility.
48:03
But remember, if that raw balancing tank is always full or is full most of the time, you actually don't have any spare storage volume to accept a from the primary activity.
48:18
So, you always need to consider actually how much volume is available to contain the spill. You need to think about pathways.
48:28
So, lost to ground and then through surface water and drainage systems.
48:31
This is probably the most important way that liquid gets off site.
48:35
All potential pathways for sources to escape containment should be considered. Factoring pathways such as the soil and the ground.
48:43
Again, you end with high, medium or low rating receptors.
48:48
You will need to consider the receptors in your assessment and you need to use reliable sources of information and to quote them.
48:55
So an example here is the Magic Mag system on the gov.uk website.
49:03
Combining all of those source pathway receptors together gives you a site hazard rating, likelihood of loss of containment should be factored in.
49:11
that's how good are your overtopping controls, how likely is it that a particular type of tank will or won't fail catastrophically.
49:19
Then any assessment should include a list of recommended actions that are reasonable given the conclusions of the assessment and dates by which they will be completed.
49:34
You'll need to include an adequate level of detail so each vessel and the bund Surrounder get should have a containment classification rating where Class 1 has a base level of integrity, Class 3 has the highest degree of integrity.
49:50
Any Class 3 containment should be demonstrated how leakage is detected.
49:55
There must be reasonable calculations included in any assessment to show how you've calculated the volume of secondary containment bunds.
50:04
Taking into consideration the factors of rainfall, fibrillation and freeboard, should be clearly stated within the report.
50:13
Catchment areas of tanks and bundling should be clearly defined in terms of materials of construction and whether they are suitable for the inventory in the event of a spillage or incident.
50:25
If you're too vague, the regulator will simply return with lots of questions asking you for further details.
50:32
But conversely, if you just and overwhelm the regulator with too much detail or often worse, constant referencing to other documents that aren't necessarily included within the Syria report that you present to the regulator and you expect the regulator to draw conclusions from these other documents.
50:54
Again, this will just simply result in questions coming back from the regulator asking you to explain yourselves more clearly.
51:01
So, there is a balance to be struck of being fear and precise in what you present to the regulator without expecting the regulator themselves to do too much inferring and interpretation of your designs to try and understand what it is you're trying to tell them.
51:20
Whenever you write your Syria report, one of the most important tables in the Syria guide is Table 6-2, a summary of key design recommendations.
51:30
This takes you down a list of design considerations, parts of the Syria guide that provide the detail that you need, and some comments on what type of class of bond this section does or doesn't apply to.
51:51
It's always best to run down this table, 6.1, and make sure you're able to provide an answer to each of those design elements and whether or not your design includes them, whether you've considered it and if you're not providing what the guide expects you to provide, giving an explanation as to why not and what justification you've got for doing so.
52:16
So to obtain the guidance, you can obtain it from the Syria website.
52:22
It can be freely downloaded, download with Syria as they like to know how many people out there are using it.
52:36
Also, finally to note, the guide is in the process of being updated.
52:41
It's taking some time, but there will be an update in the next year or two of the guide that will hopefully help in its use in industry.
52:53
But it's are considering how to react to the changes in climate change.
53:04
Much more emphasis is now being put on to how run-on into containment areas is being controlled, so flooding of these types of facilities from external floodwaters.
53:19
So has overwhelming of the bund and primary storage by floods been considered?
53:24
has the inability to remove inventory due to flooding of nearby transport systems being considered when defining the freeboards required in bonds, has increased rainfall amounts being considered due to climate change when designing the infrastructure.
53:41
Those kinds of considerations are now much more topical than they were previously.
53:49
Attaining assistance, clearly if you require any of these types of assessments to be undertaken.
53:57
SLR can help you with that, right the way through from a simple inspection, all the way through to writing your reports, and then some of the more complex modelling and investigative work that may spill out if you have a non-standard solution to providing containment. So that's me finished.
54:23
I guess we're over to questions if we have any. Thank you very much Dave for the presentation.
54:31
We have a couple of questions which have come in so if anyone's got any others please do put them into the questions box.
54:37
The first one is how would you get data slash info on rainfall amount for a specific location?
54:45
So to get rainfall analysis you register with the Flood Estimation Service and you can buy that data for a single XY coordinate.
54:59
Again, it's something that SLR as a consultancy, we have a registration with the Flood Estimation System.
55:10
It's something an individual company can do themselves as well.
55:16
Within the guide, there is a section with the link to the Flood Estimation Handbook Service.
55:25
I'm frantically leafing through my guide as I speak to try and find you the reference, but if you get the Syria Guide there is a section with a map that shows you rainfall amounts in very general terms as a first kind of stop to estimating the rainfall, but it also provides you with the to where you can obtain the accurate information for your individual site.
55:52
Cool, thank you.
55:54
We've had another question that has come in which says, I work for a food business that has several sites.
56:01
Most of the liquids we store are cleaning chemicals and oils to make in products. Would Syria apply to us?
56:06
Yes.
56:09
So, yeah, typically that is the case at food manufacturing facilities is it is often the CIP washing of your production facility with its cleaning chemicals that gives rise to both an effluent that requires secondary containment, but also the products themselves require adequate secondary containment.
56:39
If you're using fairly small volumes, so you just have kind of hand-carryable cartons, it's a fairly simple solution.
56:50
There are many proprietary bonding arrangements you can have for small volumes of cleaning chemicals.
56:56
If you're using bulk chemicals, then yes, you'd need to start thinking about secondary containment of your bulk chemical tanks, secondary containment of the delivery pipe work from the point of storage to the point of use, and you need to start thinking about how the vehicles delivering bulk supplies are provided with containment whilst transferring from the vehicle to your bulk storage.
57:26
Brilliant, okay.
57:27
We have one more question, and if anyone's got any others, please do put it in now before we finish up.
57:33
but the final one was just, will the recording be available afterwards?
57:37
And yes, it will be, so we'll be sending you an email in the next couple of days, which will have a link to the recording, the slides, and Danny's contact details, if you've got any full-on questions.
57:47
But yeah, I don't know if there's anything else in there, and if there's any final remarks for you, Danny?
57:53
No, I'd say I'll parcel this presentation up so you can send that out as well, and that will have my contact details on the back of it if anyone does want to contact us has any further questions? Cool, we've just had one come in in the meantime actually.
58:09
Please could you provide a little more explanation of when and where primary containment such as transfer pipes and pumps should have secondary and tertiary containment?
58:22
So your transfer pipes and pumps are all primary containment and so should be within some form of secondary containment and it depends whether a whether you have secondary containment so on a typical say an effluent treatment plant what would typically happen is that the entire plant would be within a bund and all of its pipe work would be within the bund.
58:55
On a production facility for food that's often not the case what you'll have is pipes running around the facility that contain potentially polluting liquids.
59:05
So if you think of a dairy, there will be a tank where you receive your warm milk from your suppliers.
59:11
It will then be piped into the dairy where it will be pasteurized, et cetera, et cetera, and then piped back out as a final product into another tank, waiting for tankers to collect it.
59:23
All of those elements really require secondary containment.
59:27
so your reception vessel requires secondary containment, pipes in and out of your facility require secondary containment, your pasteurizing tank requires secondary containment, and then the pipe out to the storage vessel for off-site product, they all require secondary containment.
59:46
It's typically, when you think of a dairy facility, a difficult thing to do retrospectively, And that's where, particularly in the food and drink industry, there is a reliance placed often on tertiary containment, so you might be able to realistically provide a bond around your bulk raw milk and your bulk milk product tanks, but the internals of the factory and the pipe work running in and out of it, it's going to be much more difficult to actually retrospectively supply that secondary containment, and that's where you would rely on tertiary containment.
1:00:26
And typically that involves things like sensors on your surface water final outlet point that would be able to detect the presence of milk in a flow of water, as opposed to clean water, shut off your drainage, enact an emergency procedure that effectively floods a local car park, et cetera, on your facility that has adequate curbing around it to provide enough storage volume.
1:00:55
Cool well thank you very much.
1:00:57
I think we're a minute over so we'll wrap up now if anyone's got any other questions and please do feel free to get in touch afterwards.
1:01:04
Yeah thank you very much Danny and thanks very much for answering the questions and yeah I hope that we see you all at the webinar again soon.
Speakers
Speakers
Danny Jones - Technical Director – Process Engineering - Assistant author for CIRIA C736 update (on-going with CIRIA)
MSc Environmental Protection
BSc Geology
Chartered Institute of Waste Management
25+ years experience of treatment plant operations at multiple sites across UK, experience of wastewater treatment globally.
Experienced secondary containment auditor / assessor for CIRIA C736, CIRIA C736 training and assessment for EA, author of ICoP for Secondary Containment at Landfills.
