One person’s trash may indeed be another’s treasure, as Salt Spring’s largest water provider received a thumbs-up from a testing lab on recycling one byproduct of water treatment — and safely discharging the other into the ground.
“We had our centrate and ‘cake’ — dewatered sludge — tested,” said North Salt Spring Waterworks District (NSSWD) operations manager Ryan Moray, updating the district board Thursday, Oct. 26. “It came back very positive for [use as] a soil amendment.”
Moray reached out for clarification to MB Labs, whose personnel have been doing water quality testing for NSSWD for more than two decades.
“I asked them their thoughts on re-use,” Moray said. “I just wanted to make sure that I was on the right track, and they sent out a quite positive letter of support.”
The dewatered component could be used as a product for land application, said Moray, and the centrate — the water from which most solids have been removed — was cleared to be discharged back into the ground for “natural infiltration.”
Moray said NSSWD was working with a consultant to consider locating a site for infiltration ponds, where the combined liquid byproduct from the water treatment plant could be discharged — and where the remaining sludge could be harvested for “secondary beneficial re-use,” he said, “such as for soil amendment.”
The plan was very preliminary, Moray told the board — more of a roadmap so far — but could produce real savings over time.
“Long-term operations costs could be reduced significantly,” said Moray, “because currently we’re hauling [the waste product] from St. Mary to a storage tank at Burgoyne, and then there’s another fee to haul it off-island to have it treated.”
The method could likely also be used at the upcoming Maxwell Lake dissolved air flotation plant for its waste product as well, Moray said, although plans there recently hit a snag: the archaeological consultant previously contracted “had not returned calls for over eight months,” according to a NSSWD operations report, forcing the district to re-start that provincially mandated work in advance of construction.
“It had seemed like work would be proceeding forward,” said Moray, “but progressively, communication fell apart. So we had to start from scratch [with a new contractor]. We’ve since completed the preliminary field reconnaissance with Stantec.”
Costs for that work are similar to those for the unfinished preliminary assessment, according to Moray, and although the new contractor seems to be moving quicker than anticipated, there was still moderate concern about the plant being completed in time to meet Island Health’s deadline of the end of 2025.
“What I can say is that Island Health has already been generous enough to extend the date from July,” said Moray. “I feel that as long as we’re working toward the goal, on track, and doing our due diligence to see that the plant is constructed in accordance with the regulatory requirements, we’ll be in good standing there.”