EPA compliance requirements

The EPA's AG1 guidance note explicitly states that it’s a requirement of all IE, IPC, and Waste licences to provide safe and permanent access to all sampling and monitoring points. Facilities that fail to incorporate proper monitoring locations during design could incur: License condition non-conformances during EPA inspections Difficulties demonstrating compliance with Emission Limit Values (ELVs) Increased monitoring costs due to access difficulties or non-standard methodologies Potential license review or enforcement action

Why Stack Monitoring location planning during design could save facilities thousands

When designing a new industrial facility, stack emissions monitoring location planning is often treated as a complete afterthought, addressed usually only after construction is complete.

This reactive approach can lead to significant compliance challenges, costly retrofitting, and operational difficulties.

By taking a more proactive approach to planning the location of stack monitoring during the site design phase, huge benefits can be made when it comes to benefits for regulatory compliance, operational efficiency and cost management.

The Irish Environmental Protection Agency (EPA) has established stringent requirements for stack emissions monitoring through their Air Guidance Notes (AG1 and AG2). These requirements mandate that facilities subject to Industrial Emissions (IE) Licences, Integrated Pollution Control (IPC) Licences, and Waste Licences provide safe and permanent access to all sampling and monitoring points.

Aside from meeting regulatory obligations, the early planning of monitoring locations ensures that accurate, representative emissions data can be collected throughout the facility's operational life.

There are, however, several design considerations that should be made for stack monitoring locations…

Achieving laminar flow conditions

Arguably the most critical factor in stack monitoring location selection is ensuring laminar (smooth, non-turbulent) flow within the stack at the measurement point.

According to IS EN 15259:2007, the standard that defines requirements for measurement sections and sites, the ideal monitoring location should be positioned at least 8 stack diameters downstream from any flow disturbance (bends, fans, changes in direction, or shape changes), and at least 2 stack diameters upstream from any flow disturbance

These distances ensure the gas flow has stabilised, allowing for representative sampling across the stack cross-section. When laminar flow conditions cannot be achieved, the uncertainty around measurement increases, which can impact compliance and lead to more complex/expensive sampling protocols.

Avoiding common design pitfalls

During the planning stage, designers should avoid placing stacks or sampling locations near the following no-go areas:

Near bends or elbows, which create swirling, turbulent flow patterns that persist for considerable distances downstream
Immediately after fans or blowers, as they can introduce significant turbulence and uneven velocity profiles
Where stack diameter or shape changes, as transitions create flow disturbances that require extended distances to normalise
In locations with poor access, monitoring teams require safe, weather-protected access to conduct testing

Sampling port and platform requirements

The EPA's AG1 guidance note specifies detailed requirements for sampling facilities, looking first at measurement ports.

There must be a sufficient size to accommodate monitoring equipment (typically 100-150mm diameter minimum), with positioning to be considered, to allow equipment insertion perpendicular to gas flow.

They must be designed to allow sealing when not in use to prevent air ingress or emissions escape, and for PM10 and PM2.5 monitoring, larger ports may be required to accommodate cascade impactor equipment

…and working platforms.

Monitoring teams require safe, permanent access, with platforms designed to accommodate at least two personnel and monitoring equipment, alongside adequate weather protection for extended sampling periods, as some tests run for 5-6 weeks, while of course meeting Irish health and safety requirements for working at height.

There is, of course, a wealth of regulatory framework to adhere to when considering Stack Monitoring location planning.

In Ireland, facilities holding IE Licences, IPC Licences, or Waste Licences must engage ISO/IEC 17025 accredited monitoring contractors for stack emissions testing. In Ireland ISO/IEC 17025 accreditation can be provided by The Irish National Accreditation Board (INAB) or by United Kingdom Accreditation Service (UKAS).

In addition to ISO/IEC 17025, some accredited contractors in Ireland also hold MCERTS (Monitoring Certification Scheme) certification, which is the UK Environment Agency's performance standard for stack emission monitoring organisations and personnel. While MCERTS is a UK standard, it is widely recognised and valued in Ireland as it provides additional quality assurance beyond ISO/IEC 17025 accreditation

The EPA's AG1 guidance note explicitly states that it’s a requirement of all IE, IPC, and Waste licences to provide safe and permanent access to all sampling and monitoring points.

Facilities that fail to incorporate proper monitoring locations during design could incur:

License condition non-conformances during EPA inspections
Difficulties demonstrating compliance with Emission Limit Values (ELVs)
Increased monitoring costs due to access difficulties or non-standard methodologies
Potential license review or enforcement action

For organisations operating both north and south of the Irish border, stack design standards should consider requirements in both jurisdictions.

While the fundamental technical standards (IS EN 15259) are harmonised, there are jurisdiction-specific guidance documents and regulatory practices. SOCOTEC Ireland's cross-border capability enables us to support clients with facilities in both the Republic of Ireland and Northern Ireland, ensuring compliance with both locations.

Incorporating proper monitoring locations during initial design typically adds minimal cost to a project, often reduced to the expense of specifying appropriate port locations and ensuring adequate platform space.

Retrofitting after construction, however, can be very costly, potentially requiring:

Stack modifications or replacement
Additional structural steelwork for platforms
Hot work permits and process shutdowns
Re-engineering of ductwork layouts

With well-designed monitoring locations, there are lots of ongoing operational benefits delivered, primarily focused on the reduction of monitoring costs, with standard access and good flow conditions allowing efficient testing using conventional methodologies.

By planning, you are reducing the amount of downtime incurred, too, meaning shorter monitoring campaigns with less disruption to operations. There will also be lower insurance costs, as proper safety facilities reduce risk exposure for monitoring personnel, as well as an improvement in data quality, with representative sampling locations producing more reliable data.

Perhaps most importantly, proper monitoring location design provides confidence that emissions data accurately represents facility performance. This confidence is valuable for demonstrating compliance during EPA inspections and supporting license renewal applications.

It also helps to identify process optimisation opportunities and with the management of environmental performance reporting.

Organisations planning new facilities should engage with their emissions monitoring contractor during the design phase. At SOCOTEC, we regularly conduct design reviews for clients planning new facilities or modifications.

Our team of experts can:

Review proposed stack and duct layouts to identify potential monitoring challenges
Specify appropriate measurement port locations and dimensions
Provide guidance on platform and access requirements
Advise on flow straightening or conditioning measures where ideal locations cannot be achieved
Ensure designs meet IS EN 15259 requirements and EPA guidance

Early engagement at this level typically requires only a few hours of consultation time, but, as we’ve discovered, can prevent significant complications later.

It also helps to identify process optimisation opportunities and with the management of environmental performance reporting.

Our team of experts can:

Review proposed stack and duct layouts to identify potential monitoring challenges
Specify appropriate measurement port locations and dimensions
Provide guidance on platform and access requirements
Advise on flow straightening or conditioning measures where ideal locations cannot be achieved
Ensure designs meet IS EN 15259 requirements and EPA guidance

Early engagement at this level typically requires only a few hours of consultation time, but, as we’ve discovered, can prevent significant complications later.

Stack emissions monitoring location planning represents a critical but often overlooked aspect of industrial facility design in Ireland. Incorporating proper monitoring locations during the planning phase ensures EPA compliance, reduces long-term costs, facilitates accurate emissions data collection and provides operational flexibility.

As the country’s environmental regulations continue to evolve in response to EU directives and climate commitments, facilities with well-designed monitoring infrastructure will be better positioned to adapt to new requirements. The modest investment in proper planning during the design phase delivers returns throughout the facility's operational life.

SOCOTEC provides comprehensive stack emissions monitoring services throughout Ireland, working with clients from the design phase through operational testing and compliance demonstration. Our ISO/IEC 17025 accreditation combined with MCERTS certified personnel, ensure the highest standards of data quality and regulatory compliance.

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