New trial to reduce nitrates at Kaiapoi's Silverstream
The study at the Silverstream Reserve near Kaiapoi will determine whether a "denitrification wall" could be a viable option for reducing pollution caused by nitrates in soil.
The wall works like a groundwater filter: a solid, porous, organic substrate is placed within a nitrate-contaminated aquifer, stripping out the nitrates before the groundwater reaches the waterway. The plan at Silverstream is to use woodchip mixed with gravel aggregate from the aquifer...