Increasing rainfall intensity and more frequent storm events are placing growing pressure on existing drainage systems. School sites, which are typically characterised by large impermeable areas, limited green space and ageing drainage infrastructure, are particularly vulnerable to exceedance and surface water flooding. 

Across six schools in Essex, these pressures were already being experienced, with frequent flooding, surcharge of existing drainage systems and disruption to normal school operations. 

Working in partnership with Essex County Council, The Environmental Protection Group (EPG), alongside Carrick Construction, delivered a coordinated Design & Build service of retrofit sustainable drainage systems (SuDS). The schemes were designed to attenuate surface water runoff, reduce peak discharge rates and improve overall site drainage resilience.

Site-Specific Flood Risk Assessment

Each school presented unique drainage characteristics and constraints. Large roof areas and hardstanding generated rapid runoff, while limited infiltration potential and restricted outfall capacity contributed to localised flooding during heavy rainfall events. 

To inform the design process, EPG undertook detailed site assessments including: 

• Topographical surveys to define overland flow pathways and levels  

• Drainage investigations to identify existing network configuration and condition  

• Hydraulic modelling to assess runoff volumes and discharge requirements  

This information was used to understand existing exceedance routes, identify critical low points and determine opportunities for attenuation and infiltration. Designs were then tailored to each site, which is essential for successful SuDS retrofit within constrained school environments. 

Sustainable Drainage Design

The design approach focused on managing runoff close to the source and reducing the rate and volume of discharge to the existing drainage network.  

Key SuDS components included: 

• Rain gardens – providing a visually engaging surface storage and filtration component. 

• Bioswales – slowing conveyance and temporarily storing surface water flows  

• Permeable surfacing – reducing rainwater runoff  and flash flooding risk  

• SuDS planters – intercept and attenuate downpipe flows in constrained areas 

• Rainwater butts – offering rainwater re-use for irrigation 

• Rainwater Marble runs – drive early curiosity and passive learning 

• Green walls – promoting biodiversity and providing visual improvements 

These features work together to collectively slow runoff, provide temporary storage and promote infiltration where feasible.  

The designs prioritised surface-based SuDS features to maximise cost-benefit, provide passive low-maintenance solutions, improve biodiversity, and offer engagement opportunities within the school curriculum. 

SuDS Retrofit in Operational School Sites

All works were delivered within live school environments, requiring careful consideration of programme, access and safeguarding requirements. Construction activities were phased to minimise disruption to school operations and maintain safe access for pupils and staff. 

Key delivery constraints included: 

• Working around term-time operations to minimise disruption 

• Safeguarding and secure site separation  

• Restricted working areas and access routes  

• Coordination with existing underground services  

Close collaboration between EPG, Carrick Construction and Essex County Council ensured that designs were buildable, safely implemented and aligned with operational requirements. This integrated delivery approach is critical when retrofitting SuDS within constrained educational settings. 

Additional Benefits of SuDS Retrofit

While the primary objective was the reduction of surface water flood risk, the SuDS features also delivered wider environmental and educational benefits, including: 

• Improved water quality through vegetated filtration and sediment capture  

• Increased biodiversity through planting and habitat creation  

• Enhancement of external learning and amenity spaces  

• Special Educational Needs (SEN) tailored planting to offer sensory spaces for students 

• Visually engaging interventions to drive early curiosity and passive learning. 

The installed rain gardens and landscaped SuDS features now form visible and functional elements of the school environment, supporting both drainage performance and educational value. 

Scalable SuDS Retrofit Approach

This project demonstrates how SuDS retrofit can be successfully implemented across multiple school sites with varying constraints. By combining site-specific assessment, surface-based attenuation and collaborative delivery, effective reductions in surface water flood risk were achieved. 

As rainfall intensity and urban drainage pressures continue to increase, retrofit SuDS schemes such as these provide a practical and scalable approach to improving resilience across existing school estates, while delivering additional environmental and community benefits. 

The Environmental Protection Group strengthens Board to enhance delivery for clients and support next phase of growth

The Environmental Protection Group (EPG) has announced the expansion of its Board of Directors, marking a significant milestone in the consultancy’s continued growth and long-term development, further strengthening its ability to support clients with complex development challenges across the UK.

Founded by Paul Culleton and Diane Leigh and shortly after joined by Steve Wilson, EPG was established at a time when sustainable drainage systems (SuDS) and vapour and ground gas mitigation were not widely recognised within UK development. From the outset, the founders challenged conventional practice, helping to shape industry understanding and setting a strong technical foundation that continues to underpin the business today.

Since becoming part of STRI Group, EPG has experienced sustained growth, expanding from a team of ten to nearly 40, following the recent acquisition of Hafren Water. This has added further depth to its expertise and ability to provide agile responses to client needs.

To support the next phase, EPG has appointed three new Directors to its Board:

Phil Williams, Managing Director
Amy Juden, Director
Leo Phillips, Director

Phil Williams commented, “As EPG moves forward, the strengthened Board provides a robust platform to support continued growth, technical excellence and long-term value for clients across geoenvironmental engineering, structural waterproofing and sustainable water management.  We have a great team surrounding us and we’re looking forward to what the future holds.”

These appointments recognise the leadership, technical capability and long-standing commitment Phil, Amy and Leo have demonstrated in helping to build and shape the business, ensuring clients continue to benefit from technical leadership, responsive service and ongoing innovation. 

The Environmental Protection Group strengthens Board to enhance delivery for clients and support next phase of growth

The Environmental Protection Group (EPG) has announced the expansion of its Board of Directors, marking a significant milestone in the consultancy’s continued growth and long-term development, further strengthening its ability to support clients with complex development challenges across the UK.

Founded by Paul Culleton and Diane Leigh and shortly after joined by Steve Wilson, EPG was established at a time when sustainable drainage systems (SuDS) and vapour and ground gas mitigation were not widely recognised within UK development. From the outset, the founders challenged conventional practice, helping to shape industry understanding and setting a strong technical foundation that continues to underpin the business today.

Since becoming part of STRI Group, EPG has experienced sustained growth, expanding from a team of ten to nearly 40, following the recent acquisition of Hafren Water. This has added further depth to its expertise and ability to provide agile responses to client needs.

To support the next phase, EPG has appointed three new Directors to its Board:

Phil Williams, Managing Director
Amy Juden, Director
Leo Phillips, Director

Phil Williams commented, “As EPG moves forward, the strengthened Board provides a robust platform to support continued growth, technical excellence and long-term value for clients across geoenvironmental engineering, structural waterproofing and sustainable water management.  We have a great team surrounding us and we’re looking forward to what the future holds.”

These appointments recognise the leadership, technical capability and long-standing commitment Phil, Amy and Leo have demonstrated in helping to build and shape the business, ensuring clients continue to benefit from technical leadership, responsive service and ongoing innovation. 

The Environmental Protection Group (EPG) is pleased to announce the acquisition of Hafren Water, a respected environmental consultancy specialising in hydrology and hydrogeology services.

This acquisition marks another exciting milestone in EPG’s continued growth, with Hafren Water’s hydrogeology expertise complementing EPG’s existing services and strengths with the ability to deliver integrated water and geoenvironmental management solutions across the UK and beyond.

Hafren Water brings a highly skilled team of specialists with extensive experience in hydrology, hydrogeology, water resource management, and flood risk assessment. Their technical excellence will further enhance EPG’s elite capabilities, enabling the development of groundwater and piling works risk assessments in addition to risk assessments for infiltration systems on high-risk sites, providing guidance from inception to completion of a project.

The acquisition introduces new clients and sector opportunities for EPG, especially within the quarrying industry, where Hafren Water has built a strong reputation.

Hafren Water will continue to operate under its well-respected brand, maintaining its base in Shrewsbury, and will work closely with EPG to share knowledge, expertise, and to continue delivering excellence for clients. The two businesses are committed to long-term collaboration, stability, and sustainable business development for both brands.

“We’re delighted to welcome Hafren Water into the EPG family,” said Phil Williams, Director of EPG. “Their hydrology and hydrogeology expertise will significantly strengthen our services and help us deliver even greater value to our clients. This acquisition is about long-term growth and building strong foundations for the future.”

“Joining EPG allows us to build on our existing strengths while collaborating to expand our capabilities and reach,” added Chris Leake, Director of Hafren Water. “We’re excited about the opportunities this partnership will bring for our clients, our people, and the wider industry.”

EPG looks forward to a successful partnership with Hafren Water, expanding its ability to deliver innovative, sustainable, and technically robust environmental solutions.

The Environmental Protection Group (EPG) is pleased to announce the acquisition of Hafren Water, a respected environmental consultancy specialising in hydrology and hydrogeology services.

This acquisition marks another exciting milestone in EPG’s continued growth, with Hafren Water’s hydrogeology expertise complementing EPG’s existing services and strengths with the ability to deliver integrated water and geoenvironmental management solutions across the UK and beyond.

Hafren Water brings a highly skilled team of specialists with extensive experience in hydrology, hydrogeology, water resource management, and flood risk assessment. Their technical excellence will further enhance EPG’s elite capabilities, enabling the development of groundwater and piling works risk assessments in addition to risk assessments for infiltration systems on high-risk sites, providing guidance from inception to completion of a project.

The acquisition introduces new clients and sector opportunities for EPG, especially within the quarrying industry, where Hafren Water has built a strong reputation.

Hafren Water will continue to operate under its well-respected brand, maintaining its base in Shrewsbury, and will work closely with EPG to share knowledge, expertise, and to continue delivering excellence for clients. The two businesses are committed to long-term collaboration, stability, and sustainable business development for both brands.

“We’re delighted to welcome Hafren Water into the EPG family,” said Phil Williams, Director of EPG. “Their hydrology and hydrogeology expertise will significantly strengthen our services and help us deliver even greater value to our clients. This acquisition is about long-term growth and building strong foundations for the future.”

“Joining EPG allows us to build on our existing strengths while collaborating to expand our capabilities and reach,” added Chris Leake, Director of Hafren Water. “We’re excited about the opportunities this partnership will bring for our clients, our people, and the wider industry.”

EPG looks forward to a successful partnership with Hafren Water, expanding its ability to deliver innovative, sustainable, and technically robust environmental solutions.

Myth: There is no point paying for independent specialists to design my gas protection system when the product supplier can give me a design for free!

Free designs from suppliers can lack independence and site-specific context. Using an impartial, qualified specialist ensures the design is appropriate, risk-based, and fully accountable.

If you ask a supplier to specify the products – at best you are handing them a blank cheque to over-spec the job, and at worst you’ll end up with a design that doesn’t work, and no-one to hold to account.

An independent design will include a full review of the site investigation data and gas regime on the site. We will design-out the gas protection if we can, and provide the most cost-effective design for the risk-profile of the site. Our designs include a set of site-specific drawings and construction details to allow site certainty and confidence in what is required to be installed and verified. The design report will specify the products to be used in the design and ensure these are compatible with the construction methods, structural waterproofing requirements, and gas regime for the site. All of this is backed by our contaminated land risk assessment and gas and water mitigation design expertise, and professional indemnity insurance. Advice you can trust – than we will stand by.

Would you trust the car salesman to tell you which car to buy? Or ask an estate agent how to build a house?

Myth: Pressure relief is needed (as a minimum) for all gas protection designs

BS8485 indicates that as a minimum all gas protection systems should include at least pressure relief for gases which might otherwise build up under the building, in reality for low gas risk situations (CS2) the flow of gas from the ground is sufficiently low so that pressurised gas will not accumulate below the building.

A pressure relief pathway should be considered for CS3 and above for sites where underfloor ventilation is not included.  Pressure relief systems are often overdesigned. Pressure relief pathways should consider the flow of gas from the ground which could potentially accumulate below a building and provide sufficient flow capacity so pressurisation will not occur. They do not need to keep gas below a design concentration.

High concentrations can accumulate in pressure relief systems – but the gas shouldn’t be under pressure. The sub-base under the slab if often sufficient on it’s own.

Do you see pressure relief systems in every gas protection design?

Myth: VOC membranes stop ingress of VOCs

Membranes do not stop vapour intrusion completely. All membranes have transmission rates for different contaminants, VOC membranes (if properly installed and verified) will slow down ingress of certain vapours. Depending on the levels of contamination on the site, the contaminant(s) of concern, and the form of construction it may not be enough to mitigate the risk. In particular where free product is close to the building or in direct contact with VOCs in groundwater.

The performance of VOC membranes can vary significantly between products. Inclusion of any VOC membrane in a design MUST be backed by a suitably detailed vapour intrusion risk assessment.

To inform the vapour intrusion assessment you need VOC permeation data for your membrane that you can trust. Terminating permeation tests early doesn’t allow for “break-through” of contaminants and can give a false impression of the diffusion rate. That’s why at EPG we want to see the full test results to verify the shape of the curve and confirm the published permeation data is representative. We might even send samples for testing as part of the verification, if it’s crucial to the integrity of our design.

Thickness will also affect membrane performance.  Checks should be undertaken during installation to ensure the thickness is consistent with the assumptions used in the risk assessment as it can be less than shown on product datasheets increasing vapour permeation.

As designers we have a responsibility to ensure that the products being specified are suitable and not just accept the information provided.

How often are we calling for a VOC membrane without fully quantifying the risk? Or relying on them to stop ingress entirely? Is this ever an acceptable approach? 

Myth: 0.4mm thick gas resistant membranes are suitable under a warehouse

In our designs we require gas membranes under cast in-situ concrete to be at least 0.5mm thick (between any reinforcement scrim) and free from aluminum foil.

Not all gas protection membranes are the same! They vary in terms of the materials they are made of, thickness, levels of reinforcement – and if they are bonded (integral link to cast in-situ concrete) or self-adhesive.

Membrane suitability depends on the site-specific risk, construction sequence and durability. Under a large cast in-situ warehouse slab, thin membranes and those with an aluminum foil core are likely to be damaged by the construction process. Taped seams are also unlikely to be durable enough.

A thin composite membrane might have a low gas transmission rate and be easy to work with on site for detailing – but all that’s no good if it gets ripped, punctured, or suffers chemical attack during construction of the floor.

How often do you see membranes >0.4mm being specified for gas protection?

Have you ever seen evidence of a membrane being damaged after it’s been laid and verified?

Myth: Gas membranes need to comply with BS8485 

BS8485 is a Code of Practice for designers to use when specifying appropriate gas protection products, it includes guidance for competent professionals to use to inform their designs. It is not a specification and a product cannot comply with a Code of Practice, so a membrane cannot comply with BS8485. 

Specification of the right gas resistant membrane and ancillary products requires a full understanding of the ground gas regime and other design considerations. A competent designer asks all these questions (amongst others): 

• What is the bulk gas regime? (CS classification) And is there also a radon risk and/or vapour intrusion to consider?  

• Where is the membrane placed, above or below the floor? 

• Is there the potential for chemical attack of the membrane from curing concrete or contact with soil contamination? 

• How does the gas protection integrate with structural waterproofing and damp proofing requirements? 

• How will the membrane be detailed at edges, joins, penetrations, level changes, etc., and is it sufficiently flexible for the detailing required? 

• Are there compatible products available to achieve a continuous gas resistant layer across the full footprint of the building (self-adhesive, sealants, liquid applied)?  

• What stresses and strains will it come under during construction, is it robust enough and do I need to specify protection layers? 

• Is there the potential for ground settlement or heave? 

• Does the design life of the structure require joins to be welded rather than taped, are there other reasons welded joins could be required, e.g. VOCs? 

• Could a more robust membrane with a higher gas transmission rate be suitable for the development where mitigation is also provided by the structure?  

At EPG, we provide a comprehensive independent gas protection design service, in accordance with the BS8485 Code of Practice, but also backed up by a wealth of experience in this area. We understand that clients and developers want things to be simple, unfortunately gas protection design isn’t as simple as some manufacturers or installers would like you to believe – but with EPG on board, we can ask all the questions for you – and provide you with a site-specific design that can you can rely on.  

Have you seen a claim that a membrane complies with BS8485? 

Myth: Ground gas from shallow coal workings can be easily fixed with just a gas membrane, and if the ground investigation doesn’t find any gas I won’t even need that.

Risk assessment for emissions from coal mine workings requires a full understanding of all the potential pathways for gas and possible future changes. It’s generally more complex than gas flux from biogenic sources (landfill/Made Ground) because there is more potential for preferential pathways and accumulation of large volumes of gas in voids in the ground. Keep in mind these key points: 

• It’s easy to miss mine workings when boreholes are widely spaced.  

• Information about groundwater levels and how they change over time is key to determining if there is a risk. Flooded workings cannot generate or store gas! 

• Spot monitoring can easily miss short duration significant gas fluxes – consider using continuous methods instead. And even then, the response zones and monitoring period needs to be designed right to be robust.  

• Gas flux modelling calculations are required to design protection measures for coal mine gas emissions – you cannot use BS8485 unless you have a very low risk conceptually.  

• Some high risk mine gas sites won’t be suitable for residential development.  

If you have shallow unflooded coal workings or a shaft linked to workings on or very close to your site WATCH OUT: absence of gas during a short monitoring period does not mean a site is risk-free. 

Check out the CL:AIRE guidance for more detail HERE or the SoBRA webinar Introduction to Coal Mine Gas Risk Assessment and Protection Design by Head of Geoenvironmental, Amy Juden HERE

Do you find site investigation and monitoring for coal mine gas challenging?  

Myth: Barometric pressure is always a key driver for bulk ground gas risk

Barometric pressure can influence bulk gas movement, but is not always the dominant factor. Site geology, source strength, and construction type are also critical in understanding gas behaviour.

Soil and Type 1 sub-base have two key properties that limit the influence of pressure drops to a very small depth below a floor slab – friction to flow (head loss) and entry pressure. Testing by EPG has shown that the zone of influence from pressure drops will only extend at most 500mm below the slab and probably less than that. That is not enough to draw sufficient gas out of soils to pose a risk. This means that unless there is a large open source and an open pathway into the building then barometric pressure has minimal if any influence on gas movement into the building. Gas emissions at sites over Made Ground with a low organic content or over Alluvium will not be affected by barometric pressure changes.

Have you assessed whether changes in gas concentration in a monitoring well are due to oxygen flowing into the ground and diluting static gas rather than an increase in gas flow from the ground? Are any correlations with barometric pressure simply due to the presence of the monitoring well and do not reflect what is happening in the surrounding ground? Barometric pressure drops often coincide with rainfall which can be the actual driver.

A common myth is that falling atmospheric pressure sucked gas out of the landfill site at Loscoe and caused the methane ingress into a house that exploded. This is not correct. The gas slowly diffused into a pit in the garden that was connected to the house via a pipe and the pressure drop sucked the gas that had accumulated in the pit via an open pathway into the house. The same mechanism occurred with carbon dioxide at a site in Gorebridge in Scotland where gas accumulated below the floor slab in stone columns and pressure drops sucked it from there.

Do we focus too much on barometric pressure conditions? Should we spend a bit longer on the CSM and ingress pathways instead? Do you consider when barometric pressure drops are a risk driver for ground gas, and when they are not?

Myth: Gas risk assessment in accordance with BS8485 is as easy as multiplying two numbers together and adding up points! Anyone can do it!

Gas risk assessment requires professional judgement. BS8485 includes a scoring system, but using it effectively demands understanding of site-specific factors, geology, and gas behaviour.  

The gas screening value (GSV) in BS8485 is not calculated – it is derived based on professional judgement and a full understanding of the site conceptual model, gas sources, pathways and data quality assessment. Hazardous gas flow rates are calculated per monitoring well, per monitoring event – and are not the same as the GSV.  

We also often see misapplication of BS8485, when the data quality assessment is missing, data from deep or flooded wells is used, where response zones cross-strata or where there is no consideration of the source of the gas in the ground.  

While CIRIA C665 may provide some useful background guidance on how to do a risk assessment, watch out – the definition of a GSV has changed! Be aware of the difference – BS8485 is the current Code of Practice that should be used.

A GSV should not be used for existing buildings or on its own to consider coal mine gas risks. 

The scoring system for gas protection design in BS8485 provides a generic framework for determining the scope of protection measures, based on the bulk gas regime or characteristic situation (CS2, CS3, CS4, etc.). But producing a full design involves a greater understanding of the proposed development, risk, and an ability to check and verify the findings and recommendations of site investigation reports.

Myth: Gas monitoring wells do not need designing

Gas monitoring wells should be designed on completion of the hole, based on the strata and groundwater encountered. Response zones should be designed so that they are above the groundwater table and isolated into a single stratum that is either a pathway or source of gas that could pose a hazard.

Designing a site investigation – ensure that there is supervision and flexibility to allow design of individual response zones on completion of each borehole. Make sure that the response zones are suitable for the risk assessment method you are adopting.

Not all gas monitoring data can be used to determine the worst case gas screening values (GSVs) – flow rate and gas concentration has to be from the same stratum as defined in BS8485.

Myth: Every ground investigation on brownfield land has to include gas monitoring

Not all brownfield sites require gas monitoring. The decision should be based on a robust preliminary risk assessment and Conceptual Site Model. Whilst on some sites it’s absolutely required – unnecessary monitoring can waste time, resources, and carbon.

Gas monitoring in natural superficial deposits often leads to elevated CO2, which doesn’t pose a risk of hazardous emissions but is often misinterpreted.  If wells are installed in Alluvium, the likelihood is that they become flooded and any data is not representative – i.e. useless!

If the only viable source is urban Made Ground, are you better off doing organic carbon testing on the soil? (see CL:AIRE RB17)

Or installing a groundwater monitoring well and collecting gas monitoring data from it, just because it’s present? Perhaps gas monitoring for a road or rail schemes, where there is no receptor? We see this kind of thing all the time, and it’s frustrating.

Follow this golden rule: Gas monitoring should only ever be in the gas source (in the unsaturated zone) or in a permeable (unsaturated) pathway between the source and the receptor. If you are doing anything else, STOP. (More on monitoring well response zones coming up on the MythBusters!)

What do you think? How often do you design out gas monitoring from your site investigation?

Introduction

Imagine a proposal for a new infiltration test method that comprises filling a deep pit, of roughly estimated dimensions, with water, taking no account of wall collapse and spalling during the test, analysing the results without consideration of soil stratigraphy in the pit, is wasteful in resources such as water and gravel to fill pits and is a method considered dangerous. It would not be considered acceptable, so why does the drainage industry and Lead Local Flood Authorities continue to think that BRE 365 infiltration tests are an acceptable approach when much safer and reliable methods of infiltration tests are available? These other test methods are also especially suitable for infiltration via sustainable drainage systems?

Recent articles in AGS newsletters (AGS 2021 and 2024) have discussed the concerns of the AGS safety working group about the safety of general trial pitting methods and BRE 365 infiltration tests. In order to overcome the safety concerns tests are increasingly carried out using coarse gravel to fill the pit. This provides practical problems and also introduces concerns about the sustainability of waste gravel (in addition to the existing one of water use).

The current BRE 365 test method was first published in 1991 (BRE 1991) and the infiltration test method it describes has not changed since then (despite revisions to the document in 2003 and 2016). CIRIA Report 156 (CIRIA 1996) did propose some amendments to the test (for example it recommends that the depth of water should be comparable to that likely to occur in the infiltration system and also if soil conditions vary across a site the tests should be undertaken at 10m spacings) but this document is rarely referred to.

At the time BRE 365 was first published infiltration systems were essentially limited to soakaways that cover a small area and are relatively deep. They were also only normally used to drain small areas.

Properly designed SuDS require shallow infiltration devices dispersed around a site rather than a single large soakaway at the end of a piped drainage system. For these types of system the BRE 365 test is not suitable. Even for small single soakaways managing runoff from small roof catchments there are better ways than BRE365 to assess infiltration rates. There are often significant issues with the application of the test method and analysis of the results, as well as no assessment of surrounding ground conditions.

The industry should move from infiltration “testing” to infiltration “assessment”, because determining an infiltration rate is more than just pouring water into a hole. The ground model needs careful consideration and a full assessment using other test methods will give a better overall indication of the infiltration rate of the soil than a BRE 365 test on its own. In the ideal SuDS scenario many small tests in conjunction with good understanding of the ground model are better than a few large scale BRE tests used in isolation.

A further concern is the unnecessary and unreasonable requirement from some Lead Local Flood Authorities (LLFAs) for infiltration tests to be completed to demonstrate infiltration is not possible.

The BRE 365 test

The BRE365 test is not particularly accurate for a number of reasons (See Figure 1). There is also often scant regard paid to ground conditions when interpreting results. The dimensions of trial pits in practice are rarely, if ever, perfectly rectilinear and where gravel infill is used the porosity is often assumed rather than measured. However, such theoretical issues and the resulting variations in infiltration rate are not normally the cause of soakaway or infiltration system failure.

The most common cause of failure is that little, if any, attention has been paid to the overall ground model when designing an infiltration test programme and interpretating the results. Tests are often carried out by unqualified staff without any understanding of the ground model and there are often no robust soil descriptions provided.

Figure 1. Infiltration testing – theory and practice

The importance of the ground model is recognised in BRE 365 which requires “Examining site data to ensure that variations in soil conditions, areas of filled land, preferential underground seepage routes, variations in the level of groundwater, and any geotechnical and geological factors likely to affect the long-term percolation and stability of the area surrounding the soakaway”. Unfortunately, this aspect of the design and testing is often ignored.

The main causes of soakaway failures that are ground related (rather than poor construction or other non-ground related design issues) are all related to poor understanding of ground conditions, poor design of the testing or poor analysis of the test results as shown in Figure 2. One very serious issue that is all too common is the analysis of infiltration results in layered ground that follows the method in BRE 365. The BRE solution assumes that the infiltration out of the pit occurs evenly over the whole surface area. It is not appropriate where water only leaves the pit via a discrete stratum (figure 2a). This can underestimate the infiltration rate, leading to larger than necessary infiltration systems. However a more significant issue is where the permeable stratum is of limited extent and the ground is not suitable for soakaways, despite the test indicting it is (Figure 2b). In these cases the analysis method should be amended to take account of the strata in the test pit.

Excessive extrapolation of results where the water does not fully soak away over a working day is also an issue which generally leads to over estimation of infiltration rates (Figure 2c).

Figure 2. Issues with BRE 365 test results

There is a perception with infiltration testing that “more water and bigger pits” are better. The reason for this is the idea that soils around and below infiltration devices become saturated because of the large volumes of water entering the ground and that the bigger test takes account of the macro structure of the soil and rock and associated variations in permeability.

However, for infiltration SuDS features such as rain gardens, permeable pavements and infiltration basins there is a significant element of “interception” that occurs in the surface layers of the SuDS. This means that for the majority of rainfall events there will be no infiltration to the ground. Rainfall simply soaks into the surface layers and evaporates later.

Fully saturated conditions rarely occur in the soils around and below these types of infiltration systems. During infiltration events a field-saturated condition develops (which is not full saturation – ASTM 2016). True saturation does not occur due to entrapped air which prevents water from moving in air-filled pores. This may reduce the hydraulic conductivity in the field by as much as a factor of two compared to conditions when trapped air is not present (ASTM 2016). Field test methods should simulate the field saturated condition.

Macro structure will normally only be relevant in strata such as rock or fissured clay (and clay will not be suitable for infiltration.). The influence of macro structure or variations in permeability can be allowed for by using a greater number of smaller tests and, more importantly, by robust assessment of the ground conditions by qualified geotechnical engineers or geologists.

Good soil and rock descriptions to BS 5930: 2015 + A1: 2020 (which incorporates descriptions to BS EN ISO 14688 and 14689) are a vital part of infiltration testing. They can be used in two ways.

The first is that initial permeability assessments can be made by designers based on the soil descriptions and published permeability values.

The second is that they are required to allow designers to undertake a sense check on infiltration results, understand whether the normal analysis of the results needs to be amended (eg if all the water lost in the test has gone into a base layer of rock and all the walls are clay) and to provide information for the wider ground model.

Another important consideration is the cut and fill profile of a site. This can result in ground levels increasing or decreasing from those at the time of any site investigations. This needs to be considered when assessing the locations for infiltration tests and the design of infiltration systems.

Water companies

Water and Sewerage Companies (WaSC) are now able to adopt some SuDS including some types of infiltration system. Training to WaSC delivered by Water UK has emphasised the importance of the conceptual ground model for infiltration design and the fact that infiltration assessment is more than infiltration tests. The training also recommended that WaSC require the following to be supplied with any infiltration design:

• Reasonable assessment of geology and infiltration capacity of each stratum by a qualified geotechnical or geology professional;
• Advice from qualified geotechnical or geology professional on suitable depths and infiltration rates (with the stratum to which the rates apply identified);
• Review of final infiltration design by geotechnical or geology professional to make sure it meets the advice provided in the site investigation report; and
• Completed infiltration Checklist – SuDS Manual, Table B.6.

It also advised that there are acceptable alternatives to the BRE 365 infiltration tests such as permeability tests in boreholes.

Alternatives test and assessment methods

Is it time to reassess the use of BRE 365 and allow alternative methods of infiltration testing combined with wider assessment of the ground model? Other infiltration test methods are used successfully in other countries and there is no reason why those cannot be used in the UK. A larger number of alternative tests combined with an assessment of the overall ground model and other data will provide a much better indication of infiltration rates than a limited number of BRE tests.

The SuDS manual includes falling head tests to ISO 22282-2:2012 (completed and analysed as a test in the unsaturated zone) as an acceptable alternative to BRE365 tests. In practice they provide a reasonable alternative to testing in trial pits, providing the results are assessed in the context of the wider ground model by an experience ground engineering professional.

The borehole tests in the unsaturated zone require the ground to be pre saturated before the test, which is similar to the “test three times” approach in BBRE 365.

The AGS article in 2021 suggests that use of boreholes as a device for obtaining infiltration data is a natural ambition for AGS members seeking compliance with standards and health and safety. There is no reason why simpler and safer methods using boreholes, permeameters and ring infiltrometers cannot be used. Indeed, the design of site investigations must comply with the Construction (Design and Management) Regulations 2015. A fundamental principle of the regulations is that of elimination of hazards where possible using less hazardous alternatives. Given that there are acceptable and safer methods of infiltration testing than BRE tests then a site investigation designer is legally obliged to use the alternatives. This should be recognised by LLFAs and Water Companies.

Boreholes tests have been used successfully to assess infiltration rates for retrofit SuDS in streets where BRE tests are not practical.

For permeable paving and infiltration basins the head of water in the infiltration test should be kept low and therefore the use of the alternative methods is more suitable and reliable, which will removes the hazards associated with infiltration tests in deep trial pits.

Existing standards that may be used as guidance are:

• BS EN ISO 22282-5:2012 Geotechnical investigation and testing – Geohydraulic testing – Part 5: Infiltrometer tests), which describes various types of ring infiltrometer test; single or double ring, open and closed. These are used in other countries to assess infiltration from shallow SuDS features such as infiltration basins, permeable pavements and rain gardens (see below). They are generally suitable for testing at shallow depths and would need to be undertaken at the base of a stable and safe pit.
• ISO 22282-2:2012 Geotechnical investigation and testing – Geohydraulic testing – Part 2: Water permeability tests in a borehole using open systems. The ground around the well should be pre saturated and the results analysed as a test in the unsaturated zone. These can be undertaken to any reasonably expected depth for an infiltration device
• ASTM D5126-16 Standard guide for comparison of field methods for determining hydraulic conductivity in vadose zone. Permeameters can be used in boreholes with the common diameters typical of UK site investigations and some are available that can test at depths that can be reasonably expected for infiltration devices.

A summary of examples of infiltration testing used in various countries is provided in Table 1. It is of particular interest that the Scottish Building Standards already allow the use of constant head permeameter tests. There is no justifiable reason why this cannot also apply in the rest of the UK.

In summary all other countries determine infiltration rates using borehole, permeameter or infiltrometer tests.

When should infiltration testing be used?

A further issue is the unreasonable and unnecessary requirement from many LLFAs for infiltration tests to be completed to show that a site is not suitable for infiltration. On many sites it is often not necessary to fill a trial pit with water and sit watching it go nowhere for eight hours, just to show infiltration is not possible. A robust desk based assessment of the geology and ground conditions by a suitably qualified ground engineering professional can often be sufficient to show that infiltration is not viable. At the site investigation stage if the ground below the site is shown to comprise low permeability strata such as clay there should be no need for tests to show infiltration is not viable.

From a health and safety perspective not requiring infiltration tests in the first place, where they are not necessary is a good step forward (and follows the accepted CDM hierarchy that the first option to be chosen should be to eliminate the hazard by design if possible).

However, the consultant involved should provide a site specific, robust and well reasoned argument why infiltration is not possible. Examples of situation where this may apply are:

• Some (not all) sites where ground contamination is present. An example could be where residual hydrocarbon contamination is present that could be mobilised by infiltration drainage. Another example is where a development is located over old landfill material.
• Sites underlain by a significant thickness of clay that does not include more permeable layers (eg Lias Clay in some parts of Northamptonshire).

Permeametre tests

Constant or falling head permeameter tests can be undertaken over the same depths that BRE365 tests are normally completed. The tests are completed in boreholes which can be drilled by hand or power auger, windowless samplers, cable percussion, etc. More than one test at different depths may be necessary in layered soils (Gill et al 2023).

The test requires significantly less water than a BRE test and is more practical.

Various permeameters are available. The Guelph permeameter and similar instruments maintain a constant head of water above the bottom of the hole and rate of water flow into the soil is recorded at short intervals until it reaches a steady state. The field saturated hydraulic conductivity (K_fs) of the soil can then be calculated (Amoozegar 2020). Falling head instruments repeat falling head tests over a short length until a steady state is reached.

A photo of a permeameter is provided in Figure 3. Advantages of using permeameters are:

• The test equipment is relatively lightweight / easy to set up;
• Small volumes of water are required for each test; and
• Tests can be undertaken during drilling or windowless sampling or can undertaken separately from the main site investigation in auger holes, depending on required depth.

Figure 3. Permeameter (EPG Ltd)

A study by Bockhorn et al (2014) compared the infiltration rates obtained using a double ring infiltrometer, a Guelph permeameter and a trial pit test. Details of the tests are shown in Figure 4. All the tests were in Glacial Till comprising clay.

Figure 4. Comparison of saturated hydraulic conductivity from various tests (redrawn after Bockhorn et al 2014)

The trial pit tests were not repeated three times as per BRE 365. The pits were filled with water until a steady state outflow was attained and the infiltration recorded. The time to achieve this is not stated. The infiltrometer gave the lowest results followed by the Guelph permeameter and the highest results were from the infiltration pit. Two of the permeameter tests gave no infiltration at all which may have been due to compaction of the soils by machinery or just inherent variations in the Till across the site.

The possible reasons for the trends observed were considered to be smearing on the sides of the hole, compaction of the soils close to the surface and the fact that the pit would include infiltration via fissures in the clay and variations in soil grading.

However, it was also considered that the pit had not fully saturated the ground around it whereas the infiltrometer and permeameter tests had. It is known that typically in a BRE 365 tests the infiltration rate reduces from initial to third repeat of the test, typically by one order of magnitude. This would make the pit test results comparable to the Guelph permeameter results.

The infiltration rate of soils can show spatial variability due to the inherent heterogeneity. However this can be managed by using a suitable number of tests. The authors concluded that use of infiltrometer or permeameter tests alone would not provide a reliable indicator of infiltration rates. They concluded that data from pits gave more representative results but that the pits are highly invasive. However probably the most significant reason for the variations that was not discussed is the limited number of pits (four) in one area of the site compared to the number of permeameter and infiltrometer tests (19 and 18 respectively spread over a much wider area of the site).

The authors concluded that the most appropriate infiltration test method was to use the tests in conjunction with borehole soil descriptions and geological assessment of the ground. This requirement already applies to BRE365 tests (but is often not followed). Given the small difference between the permeameter tests and the pit tests and also accounting for saturation, it is considered that the results show that a larger number of permeameter tests and a robust assessment of ground conditions by a ground engineering professional is a reasonable alternative to BRE 365 tests. In any event, as discussed earlier, even BRE tests should be accompanied by a robust assessment of ground conditions.

The Irish Environmental Protection Agency (EPA – Government of Ireland, 2023) has conducted research on alternatives to percolation tests for waste water infiltration systems. The research included a comprehensive literature review of soil

permeability testing and design standards for onsite waste water treatment systems. The study involved assessment of a database of falling head tests in pits (over 900 tests), modelling and field tests to compare the different methods at 17 sites. In summary it was conclude that falling head infiltration tests in pits (a version of the BRE365 test, but in smaller pits) is not an ideal method and should be replaced. Constant head tests using permeameters are considered more reliable and practicable. It also emphasised that international guidance indicates that insitu permeability tests should only be used as a complement to detailed site assessments. Permeability test results should not be the main factor in assessing suitability for infiltration and there is a need for the results of the tests to be placed in the context of an accompanying assessment of the soil texture and structure.

Conclusion

The BRE 365 infiltration test has significant health and safety, practicality and sustainability issues. There are suitable alternative methods that are used by some in the UK and that are also widely used in other countries. Large scale pit infiltration tests are rarely, if ever, used in other countries to determine infiltration rates for SuDS.

The key to successful infiltration testing and design is to include a suitably qualified ground engineering professional in the SuDS design team to advise on the appropriate test methods and to interpret the results. They should also review the final design with reference to the site ground model.

The way forward to support a sustainable agenda, reduce waste of valuable natural resources and improve health and safety is to:

• Promote wider use of understanding ground models at the initial design stage and not to preferentially rely on limited study and a small data set of BRE365 infiltration tests.
• Avoid doing infiltration tests where the desk study information and preliminary assessment shows it is not viable (from a CDM perspective design out the hazard, which should be the priority);
• Use borehole, permeameter or infiltrometer tests as appropriate, if possible (design out the hazard from the testing).
• Even for larger systems consider the use of a greater number of borehole tests rather than limited BRE tests. Consider the benefits of a good geological characterisation and what benefits could be gained from having high quality data rather than the adoption of worst-case values because of limited data.
• Only use BRE tests when absolutely necessary and infill the pit with gravel to remove the hazard. Use data loggers for water level recording.

Furthermore, the analysis of infiltration test results should not blindly follow the assessment in BRE 365. If layered soils are present where water preferentially infiltrates into one layer this should be allowed for and stated. Infiltration test results should state which stratum they are applicable to. The tests should also be related to an ordnance datum level so that designers can take account of changes in ground level due to cut and fill.

The Environmental Protection Group (EPG) is pleased to announce the acquisition of Hafren Water, a respected environmental consultancy specialising in hydrology and hydrogeology services.

This acquisition marks another exciting milestone in EPG’s continued growth, with Hafren Water’s hydrogeology expertise complementing EPG’s existing services and strengths with the ability to deliver integrated water and geoenvironmental management solutions across the UK and beyond.

Hafren Water brings a highly skilled team of specialists with extensive experience in hydrology, hydrogeology, water resource management, and flood risk assessment. Their technical excellence will further enhance EPG’s elite capabilities, enabling the development of groundwater and piling works risk assessments in addition to risk assessments for infiltration systems on high-risk sites, providing guidance from inception to completion of a project.

The acquisition introduces new clients and sector opportunities for EPG, especially within the quarrying industry, where Hafren Water has built a strong reputation.

Hafren Water will continue to operate under its well-respected brand, maintaining its base in Shrewsbury, and will work closely with EPG to share knowledge, expertise, and to continue delivering excellence for clients. The two businesses are committed to long-term collaboration, stability, and sustainable business development for both brands.

“We’re delighted to welcome Hafren Water into the EPG family,” said Phil Williams, Director of EPG. “Their hydrology and hydrogeology expertise will significantly strengthen our services and help us deliver even greater value to our clients. This acquisition is about long-term growth and building strong foundations for the future.”

“Joining EPG allows us to build on our existing strengths while collaborating to expand our capabilities and reach,” added Chris Leake, Director of Hafren Water. “We’re excited about the opportunities this partnership will bring for our clients, our people, and the wider industry.”

EPG looks forward to a successful partnership with Hafren Water, expanding its ability to deliver innovative, sustainable, and technically robust environmental solutions.

SuDS rain garden and planter which were installed at Estcourt School, designed by EPG and installed by Group company, Carrick Construction

How EPG can support your application:

• Assistance in Securing Match Funding: Securing the required 50% match funding may be a challenge for some applicants. However, third-party contributors, such as local water companies, are eligible sources. EPG can support your case by modelling sewer networks alongside surface water flooding scenarios to demonstrate the potential reduction in flows to the public sewer system. This can help justify a financial contribution from the water company.
• Flood Evidence and Performance Standards: The application requires primary or secondary evidence of surface water flooding (e.g., photos or media reports). EPG can strengthen your application by interpreting Environment Agency flood risk maps and undertaking hydraulic modelling to substantiate your evidence. We can also determine and validate the required level of protection the proposed SuDS features will deliver through performance calculations.
• Demonstrating Project Readiness: Applicants should show that their project is significantly progressed and ready for delivery. EPG can prepare necessary technical reports, calculations, and drawings to support this. We can also assist with surveys, data modelling, final design work, and tender preparation, although these additional services may incur costs that are not covered by the funding.

Key Deadlines:

• Applications must be submitted by 09:00 AM on Monday, 20 October 2025.
• The window for submitting questions or seeking clarification closes at 5:00 PM on Friday, 8 August 2025. We strongly recommend beginning the application process as soon as possible to allow ample time for queries and technical preparations.

Together, we can deliver SuDS that not only meet technical standards but also bring lasting flood alleviation and environmental benefits to your area.

The gov.uk website details all requirements on eligibility and suitability Sustainable Drainage Systems (SuDS) in Schools 2026/27 – GOV-UK Find a grant. Once reviewed, EPG would be delighted to talk to you about supporting your application. Please email enquiries@epg-ltd.co.uk or call 01274 565131.

Introduction

BS 8102:2022 identifies three types of structural waterproofing: Type A (barrier or membrane protection), Type B (structurally integral systems, typically using watertight concrete), and Type C (internal cavity drainage systems). For basements requiring a Grade 3 (habitable) environment, two lines of defence are typically specified, usually a combination of Type A and B, or Type B and C, where the choice is between Type A or C for the secondary system. There has been a marked industry shift toward Type C systems in basement construction in recent years. While Type C solutions are effective when correctly designed, installed, and maintained, this growing preference appears driven more by construction convenience than long-term client benefit. The challenge is balancing what works best for the program and buildability with what serves the structure best over its lifetime.

The Appeal of Type C for Contractors

Contractors increasingly favour Type C systems for their flexibility and sequencing advantages. These systems can be installed after the structural shell is complete, which reduces coordination issues during the early build stages. They require minimal substrate preparation, which helps streamline the program, and are more tolerant of minor installation defects that typically do not lead to water ingress, unlike Type A systems, where such defects can be critical.
Furthermore, Type C systems are not reliant on dry weather conditions. As the structural shell is typically complete before installation begins, the work is usually carried out under cover. This makes Type C particularly appealing from a programming perspective, helping to avoid delays and ensuring progress can continue during the winter months.

Why Type A Is Often Better for the Client

Despite its installation demands, Type A waterproofing is a robust and often more appropriate solution from a long-term performance perspective.

Firstly, Type A systems protect the reinforcement in concrete by preventing water ingress, enhancing the durability of the structure. They also act as a barrier to contaminants and harmful ground gases such as radon, carbon dioxide and methane.

Unlike Type C systems, which rely on pumps requiring replacement every 10 years and annual maintenance to prevent blockage from free lime deposits, Type A systems are passive once installed and correctly detailed. While Type C is often the most cost-effective option during construction, the long-term maintenance cost is rarely considered. Over a typical 50-year design life, maintenance costs can run into tens of thousands of pounds.

Furthermore, Type C systems require the client to obtain annual discharge licenses for water pumped from the system. This adds an administrative burden and ongoing costs typically not factored into the initial construction budget.

Type C systems can be impractical for large developments with complex foundation details. Details such as intermediate slabs on two storey basements, column penetrations, or slip-formed lift cores adjacent to retaining walls (common in cut-and-carve projects) can compromise the continuity and effectiveness of internal drainage membranes.

Other limitations include achieving the required 150mm termination above external ground level. Since the ground floor slab typically sits below this level, this is normally achieved with additional external membrane work. Type C systems also rely on sufficient water to direct water toward sumps and outlets; however, in many cases, the system experiences minimal water ingress, which can lead to stagnant water over the building’s lifetime.

Finally, some waterproofing contractors will only install the cavity membrane once the basement is demonstrably dry, meaning that the Type C system is either underused or not engaged at all during most of the building’s life. This raises questions about its long-term value and appropriateness for certain applications.

The Practical Challenges of Type A

Type A systems require careful planning and execution. Installers must be on-site at various stages of the build, usually to install beneath the slab, behind retaining walls, and at termination details. These visits may be broken down into multiple sub-visits, depending on the complexity of the detailing.

Type A systems are less forgiving, as minor errors in detailing or workmanship can lead to water ingress. In high-risk areas, such as the underside of capping beams, construction joints, or termination details, membrane defects can coincide with structural issues like honeycombing, cracks, or voids, resulting in water penetration. Additionally, when the membrane is installed below the slab, contractors must take care to avoid damage from reinforcement. The substrate can also be difficult to work over, as it can become slippery when wet.

Type A membranes also require skilled labour, either approved contractors or installers trained by the product manufacturer. The installation requires more time, greater attention to detail, and suitable weather conditions. These factors are challenging to overcome on live construction sites, which is why some contractors avoid them.

However, these are not reasons to disregard Type A systems. Instead, they highlight the need for proper planning and site preparation, challenges that are manageable through good construction practices, as BS 8102:2022 suggests.

Striking a Balance

While buildability is a crucial factor in design development, it should not come at the expense of quality and suitability. Designers and clients should be more assertive in resisting convenience-led design decisions that may not serve the project in the long term.

Independent waterproofing specialists should be engaged from the design stage to ensure that solutions are appropriate for the structure and end user, not just for site convenience. When the waterproofing design is supplier or installer-led and provided as a complimentary service, there is a risk that design decisions may be influenced by commercial reasons. This can lead to designs that technically comply with BS 8102:2022 but aren’t necessarily the best option for the client.

Contractors may favour short-term program efficiency, but a more holistic approach considering design-life should be encouraged. Proper training and planning make Type A systems the most robust solution. In most cases, failures in Type A waterproofing are not due to flaws in the system itself, but in the quality of execution.

Conclusion

Type A waterproofing should not be dismissed solely because of installation complexity. Design decisions must be based on what is best for the structure over its lifespan, not just on construction convenience or build cost.

As independent waterproofing designers, we advocate for technical solutions that serve the long-term performance of the structure, not just the short-term needs of the contractor’s program. Type A may be more demanding to install, but it delivers better long-term value and protection for the client when executed correctly.

The Environmental Protection Group (EPG) is pleased to announce the acquisition of Hafren Water, a respected environmental consultancy specialising in hydrology and hydrogeology services.

This acquisition marks another exciting milestone in EPG’s continued growth, with Hafren Water’s hydrogeology expertise complementing EPG’s existing services and strengths with the ability to deliver integrated water and geoenvironmental management solutions across the UK and beyond.

Hafren Water brings a highly skilled team of specialists with extensive experience in hydrology, hydrogeology, water resource management, and flood risk assessment. Their technical excellence will further enhance EPG’s elite capabilities, enabling the development of groundwater and piling works risk assessments in addition to risk assessments for infiltration systems on high-risk sites, providing guidance from inception to completion of a project.

The acquisition introduces new clients and sector opportunities for EPG, especially within the quarrying industry, where Hafren Water has built a strong reputation.

Hafren Water will continue to operate under its well-respected brand, maintaining its base in Shrewsbury, and will work closely with EPG to share knowledge, expertise, and to continue delivering excellence for clients. The two businesses are committed to long-term collaboration, stability, and sustainable business development for both brands.

“We’re delighted to welcome Hafren Water into the EPG family,” said Phil Williams, Director of EPG. “Their hydrology and hydrogeology expertise will significantly strengthen our services and help us deliver even greater value to our clients. This acquisition is about long-term growth and building strong foundations for the future.”

“Joining EPG allows us to build on our existing strengths while collaborating to expand our capabilities and reach,” added Chris Leake, Director of Hafren Water. “We’re excited about the opportunities this partnership will bring for our clients, our people, and the wider industry.”

EPG looks forward to a successful partnership with Hafren Water, expanding its ability to deliver innovative, sustainable, and technically robust environmental solutions.

The Environmental Protection Group (EPG) is pleased to announce the acquisition of Hafren Water, a respected environmental consultancy specialising in hydrology and hydrogeology services.

This acquisition marks another exciting milestone in EPG’s continued growth, with Hafren Water’s hydrogeology expertise complementing EPG’s existing services and strengths with the ability to deliver integrated water and geoenvironmental management solutions across the UK and beyond.

Hafren Water brings a highly skilled team of specialists with extensive experience in hydrology, hydrogeology, water resource management, and flood risk assessment. Their technical excellence will further enhance EPG’s elite capabilities, enabling the development of groundwater and piling works risk assessments in addition to risk assessments for infiltration systems on high-risk sites, providing guidance from inception to completion of a project.

The acquisition introduces new clients and sector opportunities for EPG, especially within the quarrying industry, where Hafren Water has built a strong reputation.

Hafren Water will continue to operate under its well-respected brand, maintaining its base in Shrewsbury, and will work closely with EPG to share knowledge, expertise, and to continue delivering excellence for clients. The two businesses are committed to long-term collaboration, stability, and sustainable business development for both brands.

“We’re delighted to welcome Hafren Water into the EPG family,” said Phil Williams, Director of EPG. “Their hydrology and hydrogeology expertise will significantly strengthen our services and help us deliver even greater value to our clients. This acquisition is about long-term growth and building strong foundations for the future.”

“Joining EPG allows us to build on our existing strengths while collaborating to expand our capabilities and reach,” added Chris Leake, Director of Hafren Water. “We’re excited about the opportunities this partnership will bring for our clients, our people, and the wider industry.”

EPG looks forward to a successful partnership with Hafren Water, expanding its ability to deliver innovative, sustainable, and technically robust environmental solutions.

The Environmental Protection Group (EPG) is pleased to announce the acquisition of Hafren Water, a respected environmental consultancy specialising in hydrology and hydrogeology services.

This acquisition marks another exciting milestone in EPG’s continued growth, with Hafren Water’s hydrogeology expertise complementing EPG’s existing services and strengths with the ability to deliver integrated water and geoenvironmental management solutions across the UK and beyond.

Hafren Water brings a highly skilled team of specialists with extensive experience in hydrology, hydrogeology, water resource management, and flood risk assessment. Their technical excellence will further enhance EPG’s elite capabilities, enabling the development of groundwater and piling works risk assessments in addition to risk assessments for infiltration systems on high-risk sites, providing guidance from inception to completion of a project.

The acquisition introduces new clients and sector opportunities for EPG, especially within the quarrying industry, where Hafren Water has built a strong reputation.

Hafren Water will continue to operate under its well-respected brand, maintaining its base in Shrewsbury, and will work closely with EPG to share knowledge, expertise, and to continue delivering excellence for clients. The two businesses are committed to long-term collaboration, stability, and sustainable business development for both brands.

“We’re delighted to welcome Hafren Water into the EPG family,” said Phil Williams, Director of EPG. “Their hydrology and hydrogeology expertise will significantly strengthen our services and help us deliver even greater value to our clients. This acquisition is about long-term growth and building strong foundations for the future.”

“Joining EPG allows us to build on our existing strengths while collaborating to expand our capabilities and reach,” added Chris Leake, Director of Hafren Water. “We’re excited about the opportunities this partnership will bring for our clients, our people, and the wider industry.”

EPG looks forward to a successful partnership with Hafren Water, expanding its ability to deliver innovative, sustainable, and technically robust environmental solutions.