It is a drab-looking two-storey building covered in beige siding that very few Sudburians will ever see inside.

But the biosolids plant off Kelly Lake Road is the biggest city project in recent years, coming with a $63 million price tag.

It's a sharp contrast to the multi-million dollar "major projects" the current city council is planning, including a new arena and art gallery, or the "legacy projects" voted on in 2008 that would have seen a multi-sport recreational complex and an arts centre built.

The plant is essential infrastructure for the city, which was forced in 2015 by Vale to stop dumping partially treated sewage on the company's tailings in Lively, as it had for decades.

Since it's the city's first attempt at a public-private partnership — or P3 — some see it as a test case for some other glitzier projects, particularly a new arena.

"It's been two years. I think if things didn't go well, people would have heard about them, right?" said city engineer Akli Ben-Anteur.

He said he regularly gets calls from other cities and towns curious about how the city's partnership with Walker Environmental is working out. 

"It's complex and you need to know your stuff ... P3s are different from one industry to the other," Ben-Anteur said.

"For now, we can say this P3 did work well."

sewage sludge

After sewage sludge is run through the biosolids plant it becomes a fertiliser product that is sold to Sudbury mining companies and in southern Ontario, spread on farm fields. (Erik White/CBC )

Deal sees dollar amounts stay private

The agreement called for Walker Environmental to build the plant and run it for 20 years.

The city pays an annual operating fee, which under the terms of the deal is private information, as is how much the city receives from its 5 per cent cut of the profits from the sale of the end product from the treatment process.

Plant manager Mike Ricci-Lyddiatt said currently, all the Sudbury sludge is sold to local mining companies for the re-greening of tailings, but added that Walker Environmental is hoping to market it to northern Ontario farmers.

In southern Ontario, the sludge is in high demand for farmers looking to fertilise corn, soy beans and other crops.

"Presently down south we have three years sold product before we've even produced," said Ricci-Lyddiatt.