ACT needs clean fill to for London Circuit portion of light rail stage 2A

Finding locations to dump Canberra's unwanted rubble became a contentious cross-border issue during the stage one construction process, with hundreds of B-double trucks heading into NSW to escape the high cost of dumping fill inside the ACT border.

One of the major dump sites used was a disused Federal Highway quarry just over the border near Sutton, where an estimated 74,000 tonnes of excavated ACT light rail dirt filled the huge quarry site to the brim.

Local residents became concerned about the dubious quality of the fill dumped at the site because there was no capacity for the council to monitor it, which raised questions about the effect on local area waterways and hydrology.

Finding somewhere to dump the dirt in NSW provided massive savings for the contractors. Had they been charged at an ACT dumping rate of $11.65 per tonne, would have had to pay out $862,100.

However, the Yass Valley Council charged only application fees, a $3000 erosion control bond and a "contribution" to council of 12 cents per tonne "in respect of road maintenance" for the Sutton site.

Now the issue is oddly reversed, with a spokesperson for the ACT government declaring "we are actively seeking opportunities to locally source fill within the city limits" for stage 2A of light rail, a planned 1.7 kilometre link between the city centre with Commonwealth Park.

"We have begun contacting building companies within the ACT to identify sources of fill which could fit the requirements for use in raising London Circuit," he said.

"Any fill identified from other projects would need to be clean and would be assessed according to strict quality standards."

The truck movements required to bring the 60,000 tonnes fill into the city are expected to raise major traffic issues during the construction process and exacerbate problems with territory road surfaces already subsiding, stressed and damaged by lengthy periods of heavy rain across the ACT.

Early works have already started on raising London Circuit, with the government moving various underground utilities from their current position on London Circuit to a new alignment on Constitution Avenue, Vernon Circle and Edinburgh Avenue.

Full-blown construction on the project is expected to start next year, with the raising of the road on either side of Commonwealth Avenue expected to take about two years to complete.

It involves changing the current split-level, overpass-underpass configuration into a level intersection.

But according to several civil works contractors who preferred not to be identified, sourcing the quantity and quality of fill required for the Commonwealth Avenue project from inside the ACT will be problematic.

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One even joked that "it may be cheaper to dig the dirt from two years ago out of the Sutton quarry and truck it back into the ACT again".

Clean fill is classified as virgin excavated natural material, but much of the readily available Canberra fill available in locations such as Pialligo is contaminated builder's waste and would not meet the required Environmental Protection Authority standards.

The ACT government requires a Contamination and Material Management Plan to be prepared and implemented for the city site as part of the Construction Environment Management Plan.

"This would detail specific requirements for the importation of any material onto the site including environmental properties, tracking requirements and reporting/record keeping requirements," the government spokesperson said.

"Imported fill materials would require strict controls to ensure suitability for use within the site. This will include an independent site auditor and relevant EPA approvals."

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