Power of nature harnessed to clean wastewater

Power of nature harnessed to clean wastewater

The power of nature has been harnessed to help clean rainwater coming off Eastland Port’s upper log yard on Crawford Rd.

Eastland Port now has two rain gardens on the log yard helping remove sediment and slow down stormwater before it flows into the port’s lamella filter plant, and then into the Kopuwhakapata Stream.

“The addition of our new larger rain garden means we can now filter all the yard’s rain water twice before it hits the stream, says Eastland Port Operations Manager Rod Blake.

The rain garden works by filtering stormwater through a soil mix medium and plants which have been chosen specifically for their fibrous root systems and ability to suck up water.

The plants include flax, grass, and reeds and have been laid out randomly to look natural.

The garden is as long and wide as a full lane in the Olympic Pool and set 1.5 metres into the ground. It’s been created on the other side of the log yard wall next to Crawford Rd.

Mr Blake says the log yard is no different to a road when it gets rained on. The moving rain water picks up organic and man-made particles and finds its way into the drains and pipes that feed into Gisborne District Council’s stormwater system.

“The difference with our water is that now it will have been naturally sieved and strained through the rain garden. Then it goes through our lamella filtering plant, so I guess you could say it’s like a double wash.”

Mr Blake says stormwater and water quality are hot topics and the port is always looking for ways to reduce its environmental footprint. The rain garden works best during moderate rainfall.

The port’s rain gardens have cost around $30,000 to create. They’re similar to the two gardens people can see at the end of Grey St at Waikanae Beach. Layers of stone, sand, rock and a special organic rain water garden mix (that includes processed bark from Eastland Port) has been used under the plants.

The recent rain events have been a good test for the system, says Mr Blake “We are happy it is working the way we wanted it to and it will only continue to improve as the plants get older.”