Bureau of Customs and Border Protection in Savannah, GA use this worksheet to process PEA / SIL. It is interesting to note the $500 border line. If the request for refund is less than $500, then Entry Specialist is working on it. If the request for refund is more than $500 or it is ADD/CVD / Quota / Special Program entry, then the request is sent into the realm of Import Specialist. Obvious conclusion is that refund requests that are over $500 are subject to extra scrutiny.
Procedures for PEA / SIL are published on CBP website.