Long, wet grass and an unrealistic computerised route system are among factors blamed for continuing glitches with rubbish collections in north Norfolk.

Missed collections throughout the North Norfolk District Council (NNDC) area remained above the national norm of 35 per 100,000 last month - at 48 per 100,000 - after reaching a peak of 242 when the new system was introduced last October.

NNDC director Nick Baker, who is in charge of environmental services, said contractors Kier had clocked up 16 'default notices' for missed collections in May, triggering a penalty clause which meant the firm had to hand back 0.3pc of the contract value - �1,237.57.

But Mr Baker said many of the missed collections were due to errors by householders and stressed that the vast majority of the district's 54,000 households had experienced no disruption. He also pointed to a number of improvements, including the cleanliness of public toilets, since the eight-year contract with Kier began in April last year.

Kier used a computerised geographic information system to plan what were supposed to be the most efficient bin rounds but Scott Martin, NNDC environmental services officer, said that when put into action across rural north Norfolk 'this did not prove to be the case.'

Prolonged rain this summer had also led to people filling their garden wheelie bins with longer, wetter grass which made them heavier and more difficult to empty, causing knock-on collection delays.

Members of NNDC's overview and scrutiny committee will also hear on Tuesday that there is to be a rethink over an experimental kerbside textile collection run by Kier, aimed at supporting the Salvation Army, which has only generated 20 tonnes of goods.

'The contract with Kier hasn't bedded down as quickly as we would have liked but, overall, the performance is pretty good. Even in some areas where we have had problems, we have also had successes,' said Mr Baker.

Complaints about the cleanliness of public toilets had fallen from 19 in the last year of the previous contract, with Norse, to nine in the past 15 months.

Figures show a fall in the amount of goods being recycled across the district which Mr Martin said was mainly due to the national economic climate. People were buying, and discarding, less. Tonnages had also dropped because manufacturers were making packaging lighter.

This was generally 'a good thing' as waste prevention was more important than recycling.

Despite the fall, prices for some recycled materials had risen and the district's share of profits from their sale had increased to �483,000 last year, compared to �302,000 in 2010/2011.

John Lee, cabinet member for environmental services, added: 'Overall the contract is a success. It's fair to say there have been a few teething problems but the savings are significant.'

The new contract is saving NNDC an average of �431,250 per year.

Tuesday's meeting will hear that a further �15,000pa would be saved by scrapping thrice-yearly independent monitoring of cleanliness, no longer required by government. Mr Baker said NNDC staff would continue their more frequent, and more stringent, checks.