The amount of curbside garbage being diverted from Ottawa landfills was more than 50 per cent for the first time in 2013, but not all of the city's green bin waste is being processed at Orgaworld, the chair of the environment committee announced Tuesday.

Green bin collection increased 23.6 per cent to 83,000 tonnes in 2013, but only 69,000 tonnes of it was processed at Orgaworld.

The remaining 14,000 tonnes of green bin waste was sent to Trail Road. The city said the waste was separately collected leaf and yard waste and it was composted rather than put in the landfill.

Coun. Maria McRae said she's disappointed not all of the waste was handled by Orgaworld.

"Well, in a word, it's disgraceful that we have collected 83,000 tonnes and all that waste has not been processed," McRae told reporters after the committee meeting Tuesday.

'This city did its job,' McRae says

"This city did its job. Our residents did their job. We picked up 83,000 tonnes, why is that not being processed? That's the question we should ask," McRae added.

But the city can't answer that question. Ongoing commercial arbitration between the city and Orgaworld prevents the city from explaining, said city solicitor Rick O'Connor.

Rick O'Connor city solicitor environment committee February 18 2014

Rick O'Connor is Ottawa's city clerk and solicitor. (CBC)

"Again, Mr. O'Connor has been very strict and very clear with regards to what comments we can make about the commercial arbitration, but I'm going to leave it up to everybody else to fill in the blanks," McRae said.

She called the 51.9 per cent diversion rate in 2013 — up from 45.1 per cent in 2012 — a "significant achievement."

Blue box material collection, including plastic and glass, increased by eight per cent, while black box materials, including paper and cardboard, decreased by three per cent. But in multi-unit buildings, blue and black box collection dropped by 1.2 per cent.

Overall, waste sent to landfills decreased by 10 per cent, from 194,000 in 2012 to 175,000 tonnes in 2013.

Total waste collected fell by 0.8 per cent, from 329,000 tonnes to 326,000 tonnes.