At the Tata Steel site in Velsen-Noord, Harsco Metals Holland receives and processes steel slag. This slag is a residual product of the process by which Tata Steel makes steel from hot metal. In the past, due to dust released as a result of operations, graffiti rains occurred, causing nuisance to the surrounding area. To prevent this, the decision was made to build a new ROZA Slag Processing Hall, where operations can take place indoors.

Antea Group designed a liquid-tight Trisoplast sealing under the concrete floor of the covered slag processing hall to protect the soil and groundwater from environmentally hazardous substances in the event of damage to the concrete structure above. The predecessor of Tritech Solutions installed the Trisoplast impermeable sealing layer.