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• 2. Where unsuitable shale and clay strata are encountered in the reduced fiighwall or upper three feet of final graded spoil, an intensive deep ripping or chiseling program will be initiated. The major advantages of deep ripping are related to the physical properties of the soil. Soils are ripped to decrease compaction, increase aeration and water movement, and increase plant rooting depths (Redente and Hargis, 1985; Josiah, 1986). 3. Final graded areas having unsuitable active or potential acidity will be neutralized with amendments or covered with a minimum of four feet suitable root growth medium, including soil. 4, If none of the above procedures satisfactorily mitigate a certain problem, the Division will be notified and recommended actions will then be implemented. Peabody will maintain records of the sampling results for each logical reclamation unit. These records will be kept on file at the mine site or Division office and will be reported within the annual reclamation report. This sampling program will ensure that the Top four feet of replaced topsoil and final graded spoil is non-toxic and chemically/physically suitable to enhance plant growth. • Compactibility and ErodibilitV. Determining the compaction potential of disturbed overburden is important to assess postmine spoil condition including: hydraulic conductivity, revegetation success, landscape stability, and equipment trafficability. Generally, stability andlor compaction problems are related to soils high in shrink/swell clays, soils with large proportions of sand and clay (sandy clay texturel, and soils with approximately equal proportions of sand, sift, and clay size particle fractions (Arnold and Dollhopf, 19771• These three conditions are not highly desirable since a high shrink/swell clay content in postmine landscapes causes poor stability and low permeability conditions, a sandy clay textured soil develops surface crusting problems, and an equal particle size distribution causes excessive compaction which results in restricted water movement and root growth. The first two considerations listed above are among those used for establishing the grading system for texture. Spoils grading poor in texture are discussed within the previous subsection of this tab and in the Mixing and Mitigation of Unsuitable Material section of Tab 6. Many of the 31 overburden sample intervals that were identified as having unsuitable clay contents (Tab 6, APPendix 6-51 will be blended and diluted to • 5 Revised 4/24/91