There is a risk that a sewer drain clog is in fact a natural gas distribution line that has been inadvertently bored through the lateral or main. Underground sewer systems are often not marked. The unintentional result is that any utility line can be bored or pierced directly through a sewer lateral in what is known as a “cross bore.”
PG&E’s goal is to help increase awareness of the potential for underground natural gas distribution lines that may have been inadvertently drilled, moled, or plowed into sanitary sewers, storm sewers, and other utilities.
Learn more at http://pgecrossboresafety.com/