text: A typical turnkey 500 MWe unit FGD system retrofit requires 380,000 = man-hours , or approximately 200 person-years , of which 20 percent , or 72,000 man-hours , are dedicated to engineering and project management , 3 and roughly 40 percent of man-hours are for boilermakers .
  
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  An FGD system only needs 10,000 man hours .