One person can be designated as for
all three operators. However, if the tanks are in operation, there must
always be someone with a minimum of a Class C Operator certification
onsite. If only one person
is holding all three operator certifications, with no others holding
any certifications, that individual would need to be onsite anytime the
tanks are in operation. A lot of times one person will hold the Class
A/B Certification and then have a couple others
hold the Class C Certification in the event the individual with the
Class A/B certification is unable to be onsite.