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...

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