 Complete the following phrase:  There have been numerous occasions where under-soil heatings effectiveness has been questioned. One notable incident happened on December 27, 2005 when three stadia in the FA Premier League, supposedly equipped with under-soil heating, failed to stop their pitches being covered in thick snow - this led to the matches being postponed. Subsequently, on January 1, 2006, the Premier League investigated as to why the pitches at Macron Stadium Bolton Wanderers, Ewood Park Blackburn Rovers and St. James Park Newcastle United were not able to repel the snow. In the U.S., a notable example of the failure of an under-soil heating system occurred in 1967, when a newly installed system at Lambeau Field in Green Bay, Wisconsin failed before the NFL Championship game. The game would go on to be remembered as the 