Halifax pioneered large-scale curbside collection of organic material in Canada 20 years ago. Now, the city is searching for a company to manage its organic waste for up to 35 years.

"For Halifax it's a big deal," said Matt Keliher, the city's manager of solid waste. "It's a big contract. It's a long-term contract and we want to make sure we get it right."

This week, the city will find out which companies want to be on the short list to design, build, own and operate its organic composting system under a 25- to 35-year deal. On Tuesday, it will open a request for qualifications from interested bidders.

The quality of the compost that's come out of the two facilities is poor. (Kevin Wentzell)

At today's prices, the contract could be worth $250 million. Keliher said the city wants to drive down those costs by locking in for the first 10 to 15 years with a fixed-price contract adjusted only by inflation.

"That way we are guaranteed a set fee for 15 years — maybe it's 10, maybe it's a little bit longer. But we are really looking to confine those costs," he said.

In the past, the city has renegotiated every five years, with costs typically jumping by 20 to 40 per cent each time.

City wants to 'hand over the keys'

The municipality spends about $150 a tonne, or $8 million a year, for composting at two privately operated facilities. One is owned and operated by Miller Group and is located in the Burnside area of Dartmouth. The other, located at Ragged Lake in Halifax, is managed by AIM Environmental Group.

The leases on those facilities expire March 31, 2019.

A new operator will be expected to walk in and continue composting operations at the two sites while it upgrades or builds new facilities there. The city said composting within the municipality must be at those locations.

The city composts 50,000 tonnes of organic material a year. (Getty Images)

Bidders will have an option to build a composting facility outside the city, but the operator must use existing sites as a transfer station.

"Right now, the preference is to — on March 31, 2019 — hand over the keys to the new operator," said Keliher.

How the composting system works

The city composts 50,000 tonnes of organic material a year collected from 136,000 residential green bins and businesses.

At both locations, the organic material is screened and dumped into aerated containers for seven to 10 days. Then it is tipped onto a curing floor and cured for up to three months.

After that, it's screened again and trucked to Elmsdale Landscaping, where it is further cured for use in their landscaping products.

What comes out of the composting facilities is poor quality, as it's too wet and acidic to meet provincial Environment Department guidelines. Consultants hired to examine the Ragged Lake facility reported in 2015 the organic material is not cured long enough or turned enough times.

The next operator will be expected to comply with environmental standards.

City has to rezone parkland for expansion

Halifax is planning to expand its footprint at the Ragged Lake location to accommodate growth in composting over the next three decades. Proponents have been told they must be able to handle up to 75,000 tonnes per year.

There is no place to grow at the Burnside facility, located on Gloria McCluskey Avenue. But there's a problem with expansion at Ragged Lake.

In the early 2000s, council decided to designate the area around the Ragged Lake facility as parkland. The city is now working to rezone the area to permit composting.

That plan has its opponents.

Last October, the Western Common Advisory Committee, a volunteer citizens group, voted unanimously to reject the proposed expansion at Ragged Lake.

The bio gas option

The city is giving proponents the option to build an anaerobic digestion system, which uses micro-organisms to break down biodegradable material in airless containers. In addition to soil additives, another end product is methane gas, which can be used to generate electricity or be processed into natural gas.

Ray Côté, a professor emeritus at the Dalhousie University School for Resource and Environmental Studies, said that's the way to go. "It's an opportunity to get more out of the compost material in the future than we have in the past."

Côté said the key is finding a company with a track record in operating compost systems successfully.

He cites "horrendous" smells emanating from the Ragged Lake facility on Prospect Road.

"There have been other issues with other facilities in Nova Scotia where the roofs — the metal roofs in these buildings — get eaten away by the acid air in these buildings, which again suggests to me they were not being operated optimally," he said.