Dozer productivity - material factor

One of the Job Condition Correction Factors for estimating dozer production off-the-job (Cat Handbook, 47th edition, page 19-55) is "Material". The factor ranges from 0.60 (Rock, ripped or blasted) to 1.2 (Loose Stockpile). I am trying to ascertain what factor a large waste rock stockpile at a mine site would be that had been in place for 5+ years. Does anyone know where I can find more examples of where this factor has been used and where various material falls in the spectrum?