MEC&F Expert Engineers : MANHOLE EXPLOSION SHUTS DOWN STREETS IN UNION TOWNSHIP DURING A ST. PATRICK’S DAY PARADE

Saturday, March 14, 2015

MANHOLE EXPLOSION SHUTS DOWN STREETS IN UNION TOWNSHIP DURING A ST. PATRICK’S DAY PARADE





MARCH 14, 2015

UNION TOWNSHIP, NEW JERSEY

A manhole explosion shut down several streets and prompted businesses to be evacuated in Union Township Saturday morning.  It happened during the St. Patrick’s Day parade.

A stretch of road from the corner of Stuyvesant to Morris avenues is closed in all directions, with additional closures along Morris Avenue.

PSEG crews and firefighters responded to the scene, and say the situation is under control.

Officials say the cause of blast and underground fire is most likely due to salt and water seeping into system. A number of businesses were evacuated but were allowed to go back as of 2 p.m. No injuries were reported.

The St. Patrick’s Day parade was delayed but still went on as planned.
Source: pix11.com/nj12news.com



Manhole fires and/or explosions are often triggered by salt or the melting mixture that leaks into the underground electrical system and corrodes wires, which then ignite from electric sparks created by arcing.

A lot of times after it snows and the snow melts, salt that is put down onto the sidewalk leaks into the system and can cause fires when it hits the equipment.
What it does is it eats away the insulation that prevents the different cables from touching each other.  Once the insulation is gone, you get this effect.

The flaming wiring can then release the dangerous gas, which can leak into neighboring buildings as it builds up pressure below the manhole.  If sufficient methane gas is buildup and there is a spark from an electric arcing, then it will cause it to explode.  

Oftentimes, the gas that is buildup is coming from the leaking natural gas piping.  In New Jersey, the gas infrastructure is very-very old in many places and it consists of the old cast iron pipes.  The useful life of these cast iron pipes has long expired and essentially we are under a Russian roulette situation waiting for the next explosion to happen should the right conditions come together: sufficient leaking gas; oxygen; and a spark.  Then, boom.