As far as I know, there is not regulatory acceptance of standalone geophysical data. However, geophysical data is gaining more acceptance among regulatory agencies to be used in conjunction with site data obtained from more traditional methods.
As far as I know, there are currently no criteria for using geophysical methods directly for regulatory decisions or compliance/performance metrics (and rightly so as geophysics provides an indirect measure of regulated metrics). There are no standards for imaging or interpretation. However geophysical methods have the potential to improve capability to meet regulatory goals e.g. improved understanding of the subsurface will lead to improved remediation design. Example: Electrical imaging (also known as Electrical Resistivity Tomography [ERT]) use is encouraged as a support tool by the Washington State Dept. of Ecology, EPA, and DOE on the Hanford Site, but is not accepted as a compliance metric.