Saltair sawmill putting in artificial marsh to filter runoff

SEATTLE (Scrap Monster):  A new chapter in the effort to better manage water around Western Forest Products’ Saltair sawmill is taking shape. The company is creating a new runoff filtering system designed to collect and control surface water from the mill and surrounding area before it can make its way beyond the site into Ladysmith Harbour.

The rainwater and stormwater runoff interacting with fine woody materials and galvanized mill infrastructure will shortly all be directed into an almost natural setting.

“We want to make sure all the rainwater runoff from our site is filtered and it’s going into the ocean clean,” said Tyler Fraser, production superintendent at the mill. “Prior to this project all the surface water went into the storm drains, which would then lead to an oil-water separator before the harbour.”

Ben Matthews, mill environmental regulatory manager for WFP, said the existing runoff “in the grande scheme of industrial sites” is low risk.

“We actually, on our own accord, chose to amend our permit and level it up. That’s what this new constructed wetland will really do with the rainwater.”

Milestone Contracting is building the project, which got underway about three months ago.

The new containment structure will consist of a more than 300 metre channel of more than 200 large concrete blocks. There will also be piping and four catchment-type basins. Everything that’s dug up to put the blocks in will be re-used in the project.

Reusing and repurposing all the material on site has helped to keep the cost of the project in line.

“We processed it, right here, to make bedding sand and one-inch drain rock,” said Tim Crooks, superintendent at Milestone Contracting. “The oversized rock will be crushed into road base for the asphalt prep and such.”

The structure should be able to handle worst-case scenarios.

According to Fraser, the company should start the plantings sometime in October. The containment area will have a bed of sand and then an HDB membrane so there won’t be any leakage. Inside will be drain rock and then the growing medium.

“We will be putting in bulrushes, cattails, reeds, all kinds of native aquatic plants,” said Matthews. “There’s always going to be water in it, it’s not dry.”

It will mimic a marsh.

“It’ll prevent any impact to groundwater, as the runoff will remain inside,” Matthews said. “We also want to retain water because during the winter it’s not a big issue to keep it wet, but in the summer we need every drop, otherwise it’ll desiccate and the plants don’t like that. They’re supposed to be wet all the time.

“Eventually, snakes and frogs may make their way into it. Birds will likely use it too. We have an established constructed wetland up at Beaver Cove in Telegraph Cove that has worked perfectly. If birds want to come in this one, that’s fantastic,” said Matthews.

On the site, directly in front of where the back wall was to go, is a pole that was erected to house an osprey nest. The birds had been making their nest on the boom of a crane and the crane was needed.

Courtesy: www.peninsulanewsreview.com