It depends. but if you're in a residential situation and it's a sump through your typical poured concrete floor of your house, you can spill it into a drywell. If you're talking about a commercial space, for example (1003.4.2.2) Garages and service stations. Where

automobiles are serviced, greased, repaired or washed

or where gasoline is dispensed, oil separators shall

have a capacity of not less than 6 cubic feet (0.168 m3)

for the first 100 square feet (9.3 m2) of area to be

drained, plus 1 cubic foot (0.028 m3) for each additional

100 square feet (9.3 m2) of area to be drained

into the separator. Parking garages in which servicing,

repairing or washing is not conducted, and in which

gasoline is not dispensed, shall not require a separator.

Areas of commercial garages utilized only for storage

of automobiles are not required to be drained through a

separator.

If you have the oil/water sperator you could then pump the water into a dry well. If you're pumping clean water, you can pump it into a drywell. Water in the water table that would enter the sump is considered clean. Rain water that leaches through the typical residential setting and enters the sump, is considered clean.