Interceptors/

Separators

GPT provide efficient interceptor management services from specification & install to maintenance and repair, expert consultants ensure compliance and effective interceptor functionality.

field engineer tanking sample from interceptor chamber during an audit

field engineer wearing full PPE within an interceptor conducting repairs through confined space entry

Interceptor Management

GPT Environmental assist site operators in remaining compliant with current legislation by specifying, installing, inspecting, maintaining, and remediating interceptors.

Interceptors (also known as separators) are installed in surface water drainage systems to prevent pollution from oil, fuel, and silt. They serve as a form of tertiary containment - helping to reduce the environmental impact of spills that exceed primary or secondary containment.

They are required on high-risk sites such as car parks over 800 m² (around 50 parking spaces), vehicle maintenance areas, refuelling facilities, and industrial premises with oil storage. Our services ensure your separators remain effective, compliant, and ready to protect your site and the environment.

GPT Interceptor / Separator Services

Interceptor Installation Interceptor Repair Interceptor Audits (6-Monthly)

Interceptor Alarms Interceptor Service (5-Yearly) Creosote Separation Filter

blue interceptor/separator ready to be installed

What is an interceptor?

Interceptors are designed to remove light non-aqueous phase liquids (LNAPLs), primarily oils, and silt, from drainage systems. Oil pollutants float on the water's surface and are captured by a series of baffles that allow water to pass while retaining the oil. Suspended solids, another key pollutant, settle within the chambers and are similarly retained.

To improve efficiency, some interceptors are fitted with coalescer filters that enhance oil-water separation. Others may include automatic closure devices that activate when oil levels become too high, and interceptor alarms which alert of high oil levels between inspections. Where installed, these components must be regularly inspected and maintained to ensure continued performance.

How does it work?

Interceptors are underground assets installed into the drainage system, designed to capture rainwater runoff from surfaces contaminated with oil, preventing pollutants from entering soil and water systems.

Whilst there are a variety of interceptor designs and models, here is a general overview of their functionality:

Contaminated surface water enters the primary Chamber (1) where silt settles out and is retained.
The fuel, oil and other pollutants lighter than water, rise to the surface and are efficiently skimmed off and transferred to the separation Chamber (2).
Water from the cleanest zone in the separation chamber flows through a coalescer unit, to remove smaller globules of oil, up to the outlet Chamber (3) and thence to the outlet pipe.

diagram highlighting functionality of an oil interceptor with arrows to demonstrate waterflow direction

interceptor install project on an electricity substation with excavator in the background

Do I need an Interceptor?

The operation and maintenance of oil separators is governed by BS EN 858:2:2003 Separator Systems for Light Liquids (e.g. Oil and Petrol) Interceptors are required on sites where operations may pose an environmental risk.

They are commonly found at petrol station forecourts, car wash facilities, car parks, electrical substations, distribution yards, and food processing plants. Despite their importance, many site personnel are unaware of the presence of interceptors, resulting in poor maintenance and reduced performance.

We have extensive experience in the regulation and subsequent requirements for interceptors on a wide range of sites. Get in touch to discuss whether you require an interceptor and, if so, the next steps to achieve compliance and environmental protection.

Bund Lining

Bund Penetration Sealing

Creosote & Tanesote Pole Storage