Here is the synposis from the NTSB report, NTSB-MAR-78-4.
About 2150 EDT on April 9, 1974, the tanker M/T Elias (Greek)
which discharging crude oil at the Atlantic Richfield Company Fort Mifflin Terminal
on the Delaware River at Philadelphia, PA exploded, burned and sank.
The Elias was destroyed; five crewmembers and three visitors were killed;
four crewmembers and one visitor are missing and presumed dead.
The tanker S/S Steiniger (Liberian) at the next berth was slightly damaged
and surrounding waters were polluted with oil.
Damage to the ARCO termianl was estimated to be $2 million.
The NTSB determines that the probable cause of the accident
was the inadequate maintenance of cargo tanks and the sanitary system
which allowed volatile cargo vapors to enter compartments
containing ignition sources.
The location of accommodations over cargo tanks
contributed to the loss of life.