Report: Bolt failure caused 2010 water main break

By the Associated Press | May 25, 2011 | 11:43 AM EDT

BOSTON (AP) — The failure of bolts holding together two sections of pipe most likely caused a massive water main break in the Boston area in 2010, an independent panel has found.

The panel, appointed by the Massachusetts Water Resources Authority, looked at two possible causes. It has concluded the failure of the bolts was the most likely cause.

A report released Wednesday said cracks in the bolts' threads likely were created during or shortly after installation. The bolts were then loaded beyond acceptable levels. The panel said the cracks likely grew until one or more failed, transferring the load to the remaining bolts.

The cascading effect caused a blow-out of the O-ring joining the two sections of pipe.

The water main break led to a boil-water order for about 2 million residents.