Plus, the winds were pushing the product toward the shore instead of into the river. And at the time, there was no precipitation, which could have spread the oil.
Fries said there was no harm to aquatic life.
Monroe spokesman Adam Gattuso said that oil-containment booms affixed to the facility's pier, leading to the docks and a bulkhead, were deployed immediately. Then more booms were added outside the first ring.
"The efforts for cleanup continue, and we're going to work until everything is out of the water," he said.
A statement from the company said that employees were working closely with various agencies, including the DEP, the Coast Guard, and the Pennsylvania Fish and Boat Commission.
Also on the site were members of the Delaware Bay and River Cooperative, a nonprofit corporation organized by oil and transportation companies to respond to spills.
The company statement said, "We will be looking closely at the role the extreme weather might have played."
Officials are still investigating.
Maya van Rossum, the Delaware Riverkeeper, said that while the spill may seem small, "it is a spill nonetheless, of dangerous contamination that does not belong in our river, and I will expect the company to go above and beyond to try to make it right."