1992-07-01_REVISION - C1991078 (2)

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2 . 04 . 6 ( 2 ) Geochemical Analysis • (b) The cores from two exploratory holes were analyzed for geochemical parameters to identify physical and chemical properties of the overburden, interburden and the stratum immedi- ately below the lowest coal seam to be mined and the extent of any materials which may have an adverse effect on the environ- ment. The two exploratory holes used were CC-1-90 and CC-3-90 both of which are within the proposed permit area. No significant ground water is expected to dis- charge though the spoil piles or through the regraded surface. The potentiometric surface of the ground water in the area is some 100 feet below the lowest coal seam to be mined and imperme- able layers of shale totaling about 20-feet thick, exist between the lowest coal seam to be mined and the aquifer. See section 2 . 04 . 7 for a further description of this aquifer. The main concern with the physical and chemical properties of the overburden/interburden is whether any material exists that will adversely effect reclamation. Following is an interpretive summary to compare the analytical results obtained from the samples with established guidelines so potential prob- lems with reclamation can be identified. Results are compared with the suggested guidelines of the Wyoming Department of Envi- ronmental Quality , (DEQ) , guideline No. 1 dated November 1984 or • the Montana, Department of State Lands Guidelines , (DSL) . p The pH values of the eleven samples ranged from 3 . 6 to 7 . 6 with an average of 6 . 2 . The DEQ sets a suitable pH range for overburden and regraded spoil from 5 . 5-8 . 5 with a marginal range of 5 . 0-9 . 0 . Two of the samples had pH values of less that 5 . 0 . Both were in the CC-1-90 core hole immediately above and below the lowest coal seam to be mined. The sample" immediately below the lowest coal seam will not be disturbed so it is not a concern regarding vegetation. The pH value for the sample immediately above the coal seam was 4 . 4 . It is probable that the overburden removal process will mix this low pH material with the overburden material above which has a pH of 7 . 4 and the resulting blend will result in a suitable pH for overburden and regraded spoils . The reclamation plan will pro- vide for a monitoring plan to delineate any unsuitable areas of regraded overburden with respect to pH. From a visual observation of the core material and specifi- cally the material that exhibits a low pH, it is evident that pyritic sulfur is the cause of the low pH. 0 2 .04-8 May 1991