The ACT government is investigating a major realignment of the Monaro Highway at Hume, which would cut through Mugga Lane solar farm, skirt the boundaries of a nature reserve and pass historic buildings.
The proposal has blindsided the solar farm's owners, who first learned of it when contacted this week by The Canberra Times despite the government having already commissioned a study into the feasibility of the new route.
The study uncovered a range of potential "constraints" to a realignment, but ACT Roads Minister Chris Steel said it was "common sense" to further investigate the option.
New tender documents show the ACT government is exploring two options for a planned upgrade of Monaro Highway between Isabella Drive and the access road to Canberra prison.
The ACT and federal governments have pledged a combined $200 million for upgrades to Monaro Highway, which would also include work on the stretch between Royalla Drive and Williamsdale Road. ACT Roads Minister Chris Steel and Senator Zed Seselja last week announced the imminent release of the tender, but made no mention of the realignment option.
The first option maintains the existing alignment, but includes an overpass or underpass at the intersections of Isabella Drive and Lanyon Drive. The second is far more ambitious, proposing a major realignment of the highway to bypass Hume's industrial precinct.
The speed limit would increase from 80 to 100 kilometres per hour along the stretch of the highway under both options.
The new route would cut through a row of trees which separates the two sides of Mugga Lane solar farm before passing over a sediment basin at the southern tip of Mugga Lane landfill, according to the documents.
The road would pass grassland just south of Jerrabomerra West Nature Reserve and Woden homestead, before it reconnects with the existing stretch of Monaro Highway north of the Lanyon Drive intersection. The move could open up land west of the existing highway to be sold and redeveloped in the future.
Jeremy Smith, the executive branch manager of infrastructure delivery at Transport Canberra, said the realignment would likely cost more than the $200 million budgeted for entire Monaro Highway upgrades. But he said the option could have wider benefits, including improved road safety and opportunities from the potential land release.
The government last year commissioned engineering firm AECOM to undertake a preliminary analysis on the feasibility of the new route, given the likely impacts on the environment, historic buildings and Aboriginal heritage sites.
The report found there was no "significant environmental impediments" which would torpedo the project, but outlined a number of "constraints" which the government would need to navigate in order to deliver the realignment.
The Mugga Lane solar farm would present an immediate hurdle, the consultants found.
The government would need to buy or lease land from the farm's owners to build the highway. The row of trees - which divides the two sections of the 48,000-panel farm - would then have to be ripped up to clear the path for the road.
Dust lifted during construction work could also "impact the solar panels".
The consultants recommended the government devise a plan to mitigate the affects of dust, noise and vibrations on the solar farm's operations.
The Mugga Lane centre, which opened in 2017, is one of three solar farms built as part of the ACT government's renewable energy agenda. The government is paying the solar farm's owners for each megawatt hour of electricity it produces. Qiao Han, the vice president of the solar park's owners, Maoneng, knew nothing of the Monaro Highway proposal until contacted this week by The Canberra Times.
"We have not heard of this before - it is surprising to see," Mr Han said.
"It would have been good to be consulted about this, but they will have to at some stage because they will have to secure access to the land."
Mr Han had reservations about the potential feasibility of the new route, but would not entirely dismiss the idea until he had more information about the proposal.
"We're not going to launch a massive rebellion against the government," Mr Han said. "We just want to understand what is being proposed, and now this is public we will seek a meeting with [ACT] government ministers."
The AECOM report, delivered to the government in December 2018, said the realignment could have a "significant impact" on a population of grassland earless dragon, which is listed as an endangered species.
The government might also be forced to prepare an Environmental Impact Study to win approval for the new route, given the proposed route passed the historic Woden homestead and Jerrabomberra West Nature Reserve, according to the consultant.
Mr Steel said he expected the upgrade would occur on the existing road alignment, but said it was sensible to consider alternatives.
"It is prudent at the very early design phase to consider whether a differing alignment could be feasible and produce better community outcomes," he said.
"There are no current plans to realign the road, but it is common sense to at least ask this basic question before getting into detailed design and construction."
Mr Steel said Mugga Lane solar farm would be consulted if the route was found to feasible, but would not be drawn on why it hadn't informed the solar farm's owner.
When asked why last week's announcement made no reference to the realignment option, Mr Steel said the statement was intended to provide a "brief overview of the plan ... not various alignment options".
The tender for designs on the two upgrade options closes on May 2.
A consultant is expected to chosen within the next six months, with preliminary designs due to be presented by the end of the year.