Except as provided in RCW
70A.305.040(4) (d) and (f), a person may bring a private right of action, including a claim for contribution or for declaratory relief, against any other person liable under RCW
70A.305.040 for the recovery of remedial action costs. In the action, natural resource damages paid to the state under this chapter may also be recovered. Recovery shall be based on such equitable factors as the court determines are appropriate. Remedial action costs shall include reasonable attorneys' fees and expenses. Recovery of remedial action costs shall be limited to those remedial actions that, when evaluated as a whole, are the substantial equivalent of a department-conducted or department-supervised remedial action. Substantial equivalence shall be determined by the court with reference to the rules adopted by the department under this chapter. An action under this section may be brought after remedial action costs are incurred but must be brought within three years from the date remedial action confirms cleanup standards are met or within one year of May 12, 1993, whichever is later. The prevailing party in such an action shall recover its reasonable attorneys' fees and costs. This section applies to all causes of action regardless of when the cause of action may have arisen. To the extent a cause of action has arisen prior to May 12, 1993, this section applies retroactively, but in all other respects it applies prospectively.