(b) The department may expend funds appropriated for a response action and take a response action, without conforming to the listing of sites by tier pursuant to Section 78770, or at a site that has not been listed pursuant to Section 78760, if any of the following apply:

1. (1) The department is monitoring a response action conducted by a responsible party at a site listed pursuant to Section 78760 or at a site that is not listed but is being voluntarily remediated by a responsible party or another person.
2. (2) The expenditure of funds is necessary to pay for the state share of a response action pursuant to Section 104(c)(3) of the federal act (42 U.S.C. Sec. 9604(c)(3)).
3. (3) The department is assessing, evaluating, and characterizing the nature and extent of a hazardous substance release at a site for which the department has not been able to identify a responsible party, the responsible party is defunct or insolvent, or the responsible party is not in compliance with an order issued, or an enforceable agreement entered into, pursuant to Section 79055.
4. (4) The department is carrying out activities pursuant to Section 79065 or subdivision (b) or (c) of Section 79060.