The operators of a Langley, B.C., mushroom farm have pleaded guilty to 10 of 29 charges laid after the death of three workers at the operation in September of 2008.

Three operators of the A-1 Mushroom Substratum operation, Ha Qua Truong, Van Thi Truong and Phinh Hwu Doan, entered guilty pleas on Friday morning in Surrey Provincial Court. 

The charges were laid under the Workers Compensation Act and the Occupational Health and Safety Regulations.

Three workers died after they were overcome by toxic fumes  after a pipe carrying a compost mixture broke and released the gas. Two other workers who tried to rescue them suffered extreme neurological damage.

At the peak of the investigation, WorkSafe BC's Donna Freeman said it was one of the most complex investigations the agency had conducted and that 25 investigators were on the file.

Jim Sinclair, the president of the B.C. Federation of Labour, says the families have been waiting three years for the case to go to court, but are disappointed by the charges that were eventually laid.

"They felt it was certainly a situation that warranted criminal charges, so they weren't happy the lesser charges were laid, but they also have never seen a report or got any indication of what happened that day," said Sinclair.