A GROUP of potential third-party users of the Goldfields Gas Transmission, led by nickel miner Anaconda Nickel NL, criticised its tariff structure, claiming the charges were 1,000 per cent higher than anywhere else. Ananconda commissioned world expert Ron Hopper to examine the tariffs after which he alleged the GGT was taking advantage of a monopoly situation. WMC Ltd, Normandy Ltd and BHP Minerals Ltd jointly own the $450 million pipeline. With its partner, Glencore Ltd, Anaconda is in the final feasibility stage for its $900 million Murrin Murrin nickel project near Leonora.