PEOPLES GAS LIGHT & COKE CO

Incident Narrative

ILLINOIS IRRIGATION SERVICES LLC HAD HIT A 2 INCH MEDIUM PRESSURE SERVICE WITH A DIRECTIONAL BORING MACHINE WHILE INSTALLING A SPRINKLER SYSTEM. NATURAL GAS MIGRATED INTO THE CENTERLINE SEWER AND ENTERED THE BUILDING. AN EXPLOSION WAS REPORTED IN THE UTILITY ROOM OF THE BUILDING. PGL PERFORMED A LEAK INVESTIGATION FOLLOWING THE EXPLOSION, CHECKING SEWER, BASINS, BUILDINGS AND ANY POTENTIAL MIGRATORY PATHS. AN INITIAL READING OF 100% GAS AT THE SPOT OF THE HIT AND IN THE NEARBY SEWER BASIN. GAS WAS SECURED AT THE SITE. THE EXCAVATED AREA WAS AERATED TO ELIMINATE ANY RESIDUAL GAS IN THE GROUND. DISTRIBUTION CREW EMPLOYEES TOOK A FINAL ROUND OF BAR-HOLE READINGS USING THE CGI. NO OTHER READINGS (ZERO READS) WERE OBSERVED. SERVICE WAS PERMANENTLY REPAIRED USING 4 FEET OF NEW 2 INCH YELLOW PLASTIC PIPE AND 2 ELECTROFUSION COUPLINGS. THE SERVICE WAS PRESSURE TESTED FOR 1 HOUR, FROM THE POINT OF THE HIT TO THE RISER. THE LINE WAS PLACED BACK IN SERVICE. DUE TO MECHANICAL DAMAGE IN THE UTILITY ROOM, THE GAS WAS LEFT LOCKED OFF AT THE RISER, PENDING FOLLOW-UP BUILDING REPAIRS BY THE BUILDING OWNER AND THE UNIVERSITY CONTRACTORS. THE ILLINOIS COMMERCE COMMISSION WAS ON SITE TO INVESTIGATE THE EXPLOSION. PGL CONSIDERS THIS INCIDENT CLOSED.