VICKI SMITHMORGANTOWN, W.Va. (AP) â¿¿ The West Virginia coal mine where an explosion killed 29 men two years ago Thursday will be permanently sealed with concrete, the mine's new owner said. Virginia-based Alpha Natural Resources, which acquired the mine when it bought Massey Energy last summer, said Wednesday it will seal the portals â¿¿ large tunnels miners use to get underground â¿¿ at the Upper Big Branch mine. Boreholes will be plugged and shafts that house the huge industrial fans meant to sweep bad air out of the mine will be capped to prevent any access. The job should be finished by summer, the company said. "Everyone still has vivid memories of the tragedy and the suffering the miners' families endured," Chief Executive Officer Kevin Crutchfield said Wednesday. "For all of us in the mining industry, it is a solemn reminder of why we must always put safety first in everything we do." Meanwhile, the mother and siblings of one of those killed sued former Massey Energy chief Don Blankenship on Wednesday, along with eight other individuals they hold responsible in their lawsuit for the worst U.S. coal mining disaster in four decades. An explosion fueled by methane and coal dust ripped through the seven miles of underground corridors at the former Massey Energy mine on April 5, 2010. Starting at 3:01 p.m. Thursday, West Virginians led by Gov. Earl Ray Tomblin planned to observe a moment of silence to mark the second anniversary of the deadly blast. Pittsburgh attorney Bruce Stanley filed the suit against the former Massey executives and mine managers in Raleigh County Circuit Court for the family of fallen miner Edward Dean Jones, just before the two-year statute of limitations expired. The complaint claims deliberate infliction of emotional distress and demands compensatory and punitive damages. Blankenship, who has retired and virtually dropped from public view, did not immediately respond to efforts to get his comment on the lawsuit. His codefendants have moved on to other jobs.