(1) Prior to conducting a RI/FS under MTCA (WAC 173-340-350), the lead agency shall evaluate the available information on the hazardous substances at the facility and take one of the following steps:

(a) Make a preliminary decision that the remedial action is unlikely to have a probable significant adverse environmental impact and proceed according to WAC 197-11-259.

(b) Decide that all or part of the remedial action or its impacts are not sufficiently definite to make a preliminary determination and proceed with early scoping prior to making a threshold determination, following the procedures in WAC 197-11-265.

(c) Decide the remedial action will have a probable significant adverse environmental impact and issue a determination of significance following the procedures in WAC 197-11-262.

(2) The threshold determination shall be made at the point at which adequate information is available to evaluate the environmental impacts of the remedial action, but no later than the draft cleanup action plan.