The diocese says it discovered the spill at the Central Catholic Convent. The building had housed the Sisters of Christian Charity, who taught at Central Catholic High School until it closed nearly two years ago.
The Reading Eagle reports diocesan spokesman Matt Kerr says an underground storage tank was being removed from behind the building when crews noticed a small leak. He says about eight inches of sludge were found at the bottom of the tank, which was last used about 20 years ago.
The diocese is volunteering to excavate and dispose of the contaminated soil.
Information from: Reading Eagle, http://www.readingeagle.com/