The state government is under pressure to call for an independent assessment of plans to double the volume of Sydney rubbish being dumped at Woodlawn, outside Goulburn.

Local residents fear an increase in odour at the site and more truck movements.

The Sydney Catchment Authority is worried about contaminated liquids leaching from the dump into Warragamba dam.

Competitors charge that the operator of the Woodlawn dump, the French group Veolia, is not doing enough to recycle waste at the site, reducing the amount going into landfill.

Veolia has approval to build a 280,000 tonne-a-year waste processing plant, but has not done so.

Veolia is seeking government approval to raise the amount of rubbish dumped into the former mine site at Woodlawn from 500,000 tonnes a year to 1.13 million tonnes. Along with Sydney's waste, the dump takes waste from the ACT and refuse from some local councils.

The proposal would double the volume of waste being shipped by rail from Clyde, near Parramatta, or result in other transfer stations being developed around the city. Veolia has yet to decide its strategy on this point.

The rubbish is removed from the railway line outside Tarago and trucked the final 15 kilometres to the dump. Some locals say building a rail spur line would solve much of the problem of truck traffic on the roads.

Under the original consent conditions, no offensive odour must be detectable beyond the perimeter fencing. But local residents say a smell can pervade the area depending on the wind and other weather conditions, although there has been no formal finding in this regard.

WSN, the waste arm of the state government, which is being sold, has told the Department of Planning that Sydney will not face landfill capacity shortfalls until at least 2017-18, and perhaps much later, since Lucas Heights in the city's south will remain operational until at least 2022.

Local residents have called for an independent assessment of Veolia's application by the Environmental Defender's Office, arguing that they are unable to adequately determine some of the claims it makes.

''How do you assess whether it is fair?'' asked the secretary of the Tarago & District Progress Association, Ian Weekley.

''The community wants somebody at arm's length from the Department of Planning to address and resolve some of these issues,'' said Chris Berry, general manager of Goulburn Mulwaree Council.

Jeff Angel of the Total Environment Centre said that Veolia's unwillingness to install a waste treatment unit at Woodlawn signals it is ''not serious about our waste recycling challenge''.

Veolia's head of government relations, Peter Shmigel, said: ''We hope to be there for the long haul. We will continue to work with the local community, and be as open and transparent as possible.''