It happened shortly after 6 near Ardmore and Lancaster avenues in Ardmore.
Police say the explosion happened underground.
The force of the blast blew the lid off of the manhole, which then hit the 50-year-old woman in the ankle.
The explosion also knocked out power for several hours to some residences and businesses in the surrounding area.
Crews restored service around 3:30 p.m.
It's not yet clear what caused the explosion.