What is the procedure for an administrative trial in state of PA

You haven't provided enough information. Each agency can have its own procedures as long as they are fixed and published. Generally the agency with authority brings a matter against an individual or an individual who has been denied a benefit can bring a claim against an agency. There may or may not be a discovery period and then there is generally an less than formal trial. The side with the burden of proof speaks first and present his/her case. The other side can either rebut that argument, present their own claims or stand with making any proof. There is usually an opportunity for the party with the burden to rebut the rebuttal. After closing arguments the administrative officer can either make a decision, take the matter under advisement or can punt the matter to a court or offical of higher authority.

Regards,

Roger