Updated: October 4, 2021

Renovation of the treatment plants

The E18 Grimstad - Kristiansand highway was built through rocks that are in part very rich in sulphide. In this connection, a number of treatment plants were established in connection with sulphide-containing blasted rock landfills. The state administrator has set maximum values for what is permitted in terms of discharges of metals to the receiving water. To meet these requirements, two major treatment plants have been established: one in Mannfalldalen and one in Stordalen in Lillesand municipality. Every three years, limestone is replaced with new fresh limestone. One of the limestone's tasks is to bind the aluminum in the water that comes from the sulfide stone deposits. The limestone in combination with lye also provides the desired pH value of the water. Purified water then flows into the receiving water. Photo Trond Heia