Laserfiche WebLink
n <br />LJ <br />is nrost coamonly easoci eted with the top soil layer and the sandstone units. The highest <br />~ `pH, 8.9 occurs in 1882E in the lowest part of the sandstone directly over the upper Dakota <br />coal's Thin ancapauleti n9 an al a. <br />Acid-base potential (ABP) ranges free -48 to 239. The Wore aei die { 0 ABP) material <br />occur¢ most caomonly above the upper Dakota coal. The more bask (TO ABP) material most <br />conmonly occurs in the upper 10 ft of overburden material or in the soil layer. Core <br />1871E contains both of the extreme ABP nunbera where the +239 ABP is found in the upper 3 <br />ft of soil, and the -48 ABP if tountl directly above the O.5 ft thlek shale layer <br />encapsulatln9 the upper Dakota coal. Pyrite occurs within the coals, in the few feet of <br />materf al surrounding the coals, and occasionally to isolated pockets higher in the <br />overburden sequence. The percent pyritic sulfur calculated for She overburden rangaa from <br />.03 to 5 .6. <br />I nterbu rtlen Material. The tntarburdcn to defined as all materiel shove the lower <br />Dakota coal seam up to and ineludlrg the upper Dakota coal seam. It 1s di vi dad into three <br />separate units, Units 2, 3, antl 4; Unit 2 consists of the upper Dakota coal and <br />eneapeulati ng ahala or sandstone layers. Unit 4 conai eta of only the shale layer directly <br />• above the lower Dakota coal, and Untt 3 compri ¢as the remaS ni ng material which is mat <br />comuonly a thSCk sandstone. <br />The thickness of Ma interDUrden remains fairly constant throughout the study area varying <br />from 17 ft in the southwestern part to about 1a ft in the central and eastern pert. The <br />thi ekness of upper Dakota coal vari ea from 7.3 ft in the west to leas than 0.5 ft fn the <br />east (Table 17-7). <br />Core YB7DE contei ns naturally-occurri ng law concentratS ana of Cu, Pb, Zn, Ni, Hg, B, Se, <br />Mo, Fa and Hn. Anal yaea of antl pH ahpw a range fn Unit 2 tram 3.5 tc 8.9, in Unit 3 tram <br />6.0 to 9.0, end in Unit 4 from 4.2 to 7.9. The mat acidic mnterial occurs in 1871E (3.5) <br />wt thin the ahal es aurround(ng the upper Dakota coal. The shale above the coal has a pH o} <br />3.6 and below the coal a pH of 3.5, with a total thickness including the coal of about <br />7.7 ft. For the entire Nuela Eaat area this is the moat acidic motors al that is found. <br />The most Dasie emteri al occurs Tn 1882E Unit 3 with a pH of 9.0 and thickness of 2.9 ft <br />and in Unit 2 with a pH of 8.9 and thS Ckness of 2.9 ft. Again, these anomal oualy high pH <br />values are found to the eneapsu]ati ng shales or sandstones of The upper Dakota coal. <br />17-35 Reviand 04/11/88 <br />• <br />REVISED MARCH 2006 Attachment 2.05.6(3)-2-43 <br />