Over 300 leaks have been detected within root zones of trees in the city of Newton Massachusetts. Many hazardous leaks have been detected that required continuous action by National Grid until the conditions no longer existed. Hazardous conditions in manholes in the Nonantum section of Newton at 351 Watertown Street were reported on 5-3-2010. National Grid crews responded and imediately started to clear the manhole structures of the potentially explosive conditions. Hazardous conditions in manholes if ignited can cause subsurface fires and manhole covers to fly off as evidenced in the recent report from Philadelphia. If you smell gas or see dead or dying vegetation contact your local gas company to investigate.