There have been differing interpretations as to the applicability of 4VAC50-20-80, Alterations Permits, to subsurface drilling at embankment dams.  It is recognized that subsurface drilling could potentially affect the structural integrity of an impounding structure, and it is prudent to ensure such work is completed in a manner that minimizes risk to the impounding structure.  However, the Alteration Permit and design report process detailed in 4VAC50-20-80 includes requirements that are not relevant to a subsurface investigation while also falling short of ensuring appropriate qualifications of the drilling team and thorough planning of the drilling process.  The State should consider adopting a new written policy including a succinct and streamlined permit for subsurface investigations at dams.  This policy should also include minimum qualifications for drilling contractors.  This drilling permit would reduce the economic burden of addressing irrelevant requirements in 4VAC50-20-80 while improving the protection of public safety.  A similar program was introduced to FERC-regulated impounding structures in 2017.