INSPEC05003 - Laserfiche WebLink

Home Browse Search

Memo to Christine Johnston bleat Elk Coal Refuse Compaction page 3 comprehensively evaluated in determining proctor maximum dry densities. As a result the max dry densities used for determining relative density were too low and the relative densities calculated for field density tests were correspondingly too high in many cases. In their March memo, Messrs. Johnston and Lambert of Lambert & Associates, present an opinion that the high relative density results reflect differences in compactive loading between the test method rammer and the compactive load applied by the Caterpillar S15B in the field. While it is true that compacted density is greater with higher compactive effort, the critical factor for the Caterpillar would be the load per surface area applied not its bulk weight. Further, I think the recent testing experience of 6/13,16 & 19/95, in which Method D rock-correction Proctor analyses were performed demonstrates my point effectively. In stead of the past Method A & B analytical results with maximum dry densities in the 68 to 80 pounds per cubic foot range, the maximum dry density of one composite material was determined to be 91.5 pcf, and the other fine grained material to be 76.5 pcf. When these comparative standards were comprehensively applied to the field density tests performed a range of relative densities from 89% to 119.8% were documented. while several of the determinations still seem somewhat abnormally high, this is certainly a lot more plausible. I suspect that the several determinations above 105% may reflect coarse rock included within the detection sphere of the nuclear density apparatus, which can raise the apparent density determination. Conclusions and Recommendations MCC and the Division could easily spend man months exchanging scintillating technical trivia regarding our personal/professional opinions regarding compaction phenomena. This would consume inordinate amounts of my unavailable time and cost MCC considerable amounts of consulting and staff expertise, time and money. I note that the results of the 6/13,16 & 19/95 field testing, which present more realistic and plausible density results, also show all but one test to be within specs. That one substandard density was 1% too low and was subsequently remedied by recompaction. This fact, plus the evidenced stability of the lower refuse pile, gives me confidence that past compaction has probably been effective, only the documentation has been problematic. This is exactly how the engineering control process is intended to function. Congratulations are in order for everyone involved. My faith in the engineering and regulatory processes are once again vindicated. I believe, in order to assure that future compaction testing and