RESIDENTS of Bulga in the upper Hunter Valley already threatened by the expansion of a nearby Rio Tinto coal mine may have even more to fear with the mining giant hiring consultants to survey an expansion of the open-cut pit to within about 500metres of the town. The &nbsp;planned 698-hectare expansion of Rio Tinto’s Mt Thorley-Warkworth coal mine gained a recommendation for approval from the Planning Assessment Commission in March after courts twice knocked back earlier versions of the plans. The commission said Bulga residents should consider relocating the town as one option to minimise the noise and dust of a mine that would encroach to about 2.6 kilometres from the town, &nbsp;20km south-west of Singleton. However, a secret June 2014 report by Cumberland Ecology ordered by Rio and obtained by Fairfax Media, shows the company has scoped out a further 1370ha on both the western and eastern flanks of the current mining plans. The report was prepared for the Baird government’s Upper Hunter Strategic Assessment program to streamline future mine approvals. As Fairfax revealed in February, the project aims to determine the cumulative impacts on plants and animals of 16 proposed new and expanded coal mines covering about 45,000 hectares. &nbsp;Details of Rio’sintentions for the Warkworth mine, though, have not been made public until now. This latest expansion, if approved, would bring the mine ‘‘to right outside the village door’’, said John Krey, Bulga resident and spokesman for the Bulga Milbrodale Progress Association.&nbsp; Rio Tinto has been ‘‘trying to play it very low key’’, with the company leaving its intentions unclear for ‘‘undesignated’’ land adjoining the current mine continuation project, Mr Krey said. The miner’s current expansion has been dogged by legal troubles, including over the clearing of endangered Warkworth Sands woodland vegetation that had been previously set aside as a permanent offset by Rio Tinto when it won approval in 2003 for an earlier expansion.&nbsp; The scoping study indicated at least as much endangered vegetation is at risk, with 589ha of the threatened Central Hunter Grey Box – Ironbark woodland in the path of bulldozers. &nbsp;‘‘The impact is far, far greater than originally envisaged by the Planning Assessment Commission,’’ said Georgina Woods, &nbsp;spokeswoman for the Lock the Gate alliance. The expansion would also sever Wollombi Brook. A Rio Tinto spokesman &nbsp;declined to comment on whether the miner &nbsp;planned future mining of the 1370ha area. &nbsp;‘‘We cannot mine in this area because we do not have approval under the NSW planning system. Our focus is on securing approval for the applications we have before the NSW government to continue operating Mount Thorley Warkworth for the next twenty years, which do not include this area.’’ &nbsp;The &nbsp;spokesman denied residents would be forced to move. Bulga residents are planning to hold a protest rally in Martin Place on Monday morning.