Epic Energy has pre-empted the tariff announcement by warning that it will pursue a $50 million claim against the State Government if it is forced to cut its prices.

The claim was originally made in 1999 but allowed to lay dormant and was related to disputes over the technical aspects of the line.

Subsequently the chief executive of the WA Office of Gas Access Regulation, Peter Kolf, revealed that independent legal advice has been sought from law firm Corrs Chambers Westgarth to review the transmission tariff ruling to be handed down on the 30th of April.

Due to the financial importance of the decision to several leading firms the regulator wants to ensure that it is on the soundest legal ground before the decision is delivered.

The regulator is to decide whether pipeline owner Epic Energy is able to charge a $1 tariff per gigajoule transported, or something closer to 75 cents. Anything less than a dollar will probably see Epic's bankers put the line into receivership in order to recover debts of around $1.85 billion as it will no longer be viable at the price.

Legal options for Epic in the event of an unfavourable ruling include challenges through the Supreme Court and the WA Gas Review Board.

If the line does go into receivership it opens the way for AlintaGas to buy a stake, giving it a strong hold on the supply line as well as a large capacity allocation.

The other side of the coin is that part of the Epic deal to buy the line meant that old and new users would pay the same rate, although any expansion of the line would mean that new users should be paying around $1.40 to cover expansion costs.

However, the cost restrictions only apply as long as Epic maintains ownership. If this alters, new users could be facing a sharp rise compared to companies who already have capacity allocations.

The decision therefore has massive financial implications and the regulator is quickly trying to make sure its back is covered.