The Hume recycling centre, run by RE Group, has had build ups in recent years, notably in May this year when material was also stacked up to five bales high on the block, while growing levels of loose material have been piled up against the buildings on site.

The operator and the government have previously rejected assertions the Chinese ban was having any effect, arguing just one to two per cent of material processed on site was the type of plastic needing to be sent to China.

But RE Group's Garth Lamb on Wednesday admitted the ban was now affecting the Hume centre, as well as the combined effects of a technical fault shutting down recycling operations for two days, and changed delivery practices due to the strike, leading to a backlog of material.

The fault was in a component of machinery that sorts paper and cardboard material at the centre last week, but it took two days to obtain and install the part to get the processing machine back up and running.

Since China enacted the ban in January this year, recyclers worldwide have struggled to find markets for their product, with Australian operators left guessing at what to do with the 619,000-odd tonnes of material the nation used to send to China.

Mr Lamb said the ACT plastics needing to be sent to overseas markets still only represented about one to two per cent of the material processed here, but as the Hume centre was a large facility the small proportion was building up over time.

He could not say exactly how much material was currently being stockpiled at Hume, and the government has previously refused to say how much material is stored on site, though a spokesman has said the centre processes about 126,000 tonnes of material each year.

Mr Lamb also said the China ban was affecting the entire Australian industry, and particularly the price they could get for recycled materials, which was linked to international markets hit by China's importation freeze.

He said the strike had led to a change to normal delivery patterns, with bins missed during last week's strike having to be dropped off this week, but the technical fault had been the main contributing factor.

Mr Lamb said while the company had a large maintenance crew to keep the machinery running, it was not as easy as picking up a replacement part from Bunnings, and it took two days to get the machines operating again after the technical fault.

He said the fault had occurred at an unfortunate time coinciding with the strike and China's decision, and it had slowed processing down momentarily, but staff at the centre were now working extended hours to address it, and the backlog should be addressed by this time next week.

Mr Lamb also said while the amount had increased, ACT residents concerned about rising levels of material at Hume were able to register for a tour of the centre through the territory government to learn more about it.

A transport and city services spokeswoman said the Chinese importation ban has had "little impact on household kerbside recycling in the ACT".