I found this in the policy manual.
Visa Waiver Program Entrants – Satisfactory Departure
VWP entrants are generally not eligible for an extension of stay or change of status.[11] However, where an emergency or unforeseen circumstance prevents the departure of a VWP entrant, USCIS may exercise discretion to grant up to 30 days to allow for satisfactory departure.[12] For those VWP entrants already granted satisfactory departure and unable to depart within this 30-day period because of an emergency or unforeseen circumstance, USCIS has the authority to provide an additional 30-day period of satisfactory departure.[13] Officers determine whether an emergency or unforeseen circumstance constitutes an emergency that merits an approval of satisfactory departure.
To request satisfactory departure from USCIS, a VWP entrant should contact the USCIS Contact Center[14] and provide proof of the emergency or unforeseen circumstance. The USCIS Contact Center forwards the request to the local field office for consideration. If USCIS approves the request, the officer provides the requestor with a notification of a grant of satisfactory departure.
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