Just because the code spells out two different licensing standards, one for COSE and one for AOSE, it does not mean that DPOR must drastically alter the standards that the Board of Health required.  Keep the bar that the Board of Health set through public participation.  Those standards went through a technical review committee and public scrutiny.  They are now well established standards.  Keep a written and field test.   

A COSE must have virtually the same skills as an AOSE.  The only difference between the two categories deals with understanding of treatment and pressure dosing.  Since the skill set for both categories needs equivalent knowledge and skills for soil evaluation, DPOR should not have a significanly lower bar for COSEs.  

Keep the bar set by VDH and grandfather all people certified by the Board of Health as OSEs.  Add to this requirement some additional KSAs for the AOSE license (not additional experience). 

COSEs must be able to evaluate site and soil conditions for alternative systems to make the program work.  If COSEs can only evaluate site and soil conditions for conventional technology, then everybody will just become an AOSE