Learn how we delivered a tailored containment barrier at a complex riverside site in northern Italy, helping control contaminated groundwater and support long‑term remediation.
In northern Italy, a former chemical production site faced a serious environmental legacy. Groundwater beneath the site had been contaminated by benzotrifluoride (BTF) and per- and polyfluoroalkyl substances (PFAS), posing a major risk of pollution spreading beyond its boundary.
Working for an international oil and gas company, we were appointed as engineering, procurement and construction (EPC) contractor. Our role was to deliver a continuous physical barrier along the upgradient side of the site, where groundwater flows in, to help control and reduce contamination.
The project brought together multiple technical disciplines – hydraulic modelling, geological study, geotechnical analysis and remediation design – to develop a containment strategy tailored to the site’s complex environmental and ground conditions.
Over a 24-month programme, we supervised and coordinated complex civil and geotechnical works, helping our client take a critical step forward in its remediation strategy.
The challenge
Due to the location of the site alongside a creek, controlling groundwater was particularly challenging.
The local hydrological system is influenced by rainfall from the surrounding hills, water from the adjacent river, and natural groundwater recharge. As a result, groundwater levels and flow can vary, increasing the risk that contamination could spread beyond the site boundary unless it is carefully contained.
To prevent this, a physical barrier was required along the edge of the site. It also needed to extend deep enough to reach naturally less permeable clay and limestone layers. Without this depth, groundwater could flow beneath the structure, reducing its effectiveness.
The setting and geology added further complexity. Around 80 per cent of the works took place within the creek corridor itself. Water levels rise and fall throughout the year, and heavy rainfall can quickly increase river depth. Construction therefore had to be meticulously planned and sequenced to maintain safety, protect the watercourse and keep the programme on track.
Building a robust containment barrier
To meet these challenges, we led the delivery of the physical barrier designed specifically for the site.
The scheme included:
- A 480-metre steel sheet pile wall with a max depth of 15 metre, covering around 5,500 square metres
- A 100-metre secant pile wall with a max depth of 22 metre, covering around 1,800 square metres
- Approximately 4,000 square metres of riverbank capping works
Together, these formed a continuous underground barrier along the upgradient site perimeter.
As ground conditions varied across the site, we adapted installation methods accordingly. Steel sheet piles were installed where the ground allowed. In areas with harder soils and rock, relief drilling (pre-drilling to ease installation in dense ground) made it possible to install the sheet piles correctly. Elsewhere, overlapping concrete piles created a solid underground wall capable of reaching the required depth.
Along the creek, the capping system prevents river water from entering the site, helping reduce groundwater recharge in this sensitive area.
Delivering these works within a live creek environment required careful planning. We installed light working platforms to allow safe site operations while minimising disturbance to the riverbed and surrounding habitat.
Close collaboration between our environmental and civil engineering teams made sure environmental requirements were embedded in construction planning.
Ensuring safe and controlled delivery on site
As EPC contractor, we were responsible for delivering the containment works safely and effectively.
Our role included:
- Daily supervision of site activities
- Management of specialist subcontractors
- Coordination of civil and ground engineering works
- Technical oversight and quality assurance
- Close collaboration with the legally appointed safety coordinator
We maintained a continuous presence on site throughout the 24-month construction period. This allowed us to respond quickly to changing river conditions, manage programme risks, and ensure environmental protection measures always remained in place.
Close collaboration between our environmental and civil engineering teams made sure environmental requirements were embedded in construction planning.
We also oversaw the testing of the completed barrier to confirm it met the required performance standards.
Safeguarding groundwater and managing environmental legacy
Now completed, the barrier significantly reduces the amount of groundwater entering the site. This supports the hydraulic pumping system and helps prevent contamination from spreading beyond the site boundary.
By containing contamination at source and protecting the adjacent creek corridor, the project is supporting long-term environmental protection and helping create the stable groundwater conditions needed for the next phase of remediation.