Appendix E - Geology and Soils Geotechnical Supporting Information COMBINED

LESTER-SHRINER PROPERTY 132-8-2 Page 15 6.5 CUT/FILL OR MATERIAL TRANSITION OVER-EXCAVATION Lots with cut/fill transitions should be over-excavated to provide a relatively uniform fill thickness beneath the building footprint. On a preliminary basis, the depth of over-excavation below pad grade should be equal to the maximum fill thickness on the pad but need not exceed 5 feet, as shown in Figure 5. If material transitions are observed within proposed building or street areas, it may be necessary to over-excavate exposed bedrock materials, such as interbedded claystone materials, to reduce the potential impact on improvements due to localized expansion or heave. The depth of the over-excavation will depend on the type of material exposed and will be determined in the field during construction. In general, over-excavation should extend to at least 5 feet beyond the building footprint or street improvements. Adjustments to the depth and lateral limits of the over-excavation may need to be made at the time of construction depending on the actual conditions encountered during grading. 6.6 SUBGRADE PREPARATION After site clearing, demolition and mass excavation is complete, and prior to backfilling any excavations resulting from fill removal or demolition, the excavation subgrade and subgrade within areas to receive additional site fills, slabs-on-grade, foundations and/or pavements (including exposed bedrock cut materials) should be scarified to a depth of 6 to 12 inches, moisture conditioned, and compacted in accordance with the “Compaction” section below. 6.7 MATERIAL FOR FILL On-site soils with an organic content less than 3 percent by weight may be reused as general fill. General fill should not have lumps, clods or cobble pieces larger than 6 inches in diameter; 85 percent of the fill should be smaller than 2½ inches in diameter. Minor amounts of oversize material (smaller than 12 inches in diameter) may be allowed provided, the oversized pieces are not allowed to nest together, and the compaction method will allow for loosely placed lifts not exceeding 12 inches, such an 815 or REX compactor. Due to the interbedded sandstone and siltstone that may be exposed on some cut slopes, consideration should be given to reusing some of the native topsoil to provide soil cover for finished graded slopes to aid in re-vegetating finished slopes for erosion control. Topsoil should be spread thinly over a section of on-site materials, moisture conditioned and thoroughly blended or track-walked. The necessary topsoil layer thickness will depend on the stripping organic content and the feasibility of stockpiling topsoil materials during site grading. 6.8 COMPACTION REQUIREMENTS On a preliminary basis, all fills, and subgrade areas where fill, slabs-on-grade, and pavements are planned, should be placed in loose lifts 8 inches thick or less and compacted to at least 90 percent relative compaction in accordance with ASTM D1557 (latest version) requirements. Keyway fill or fills greater than 5 feet deep should be compacted to at least 93 to 95 percent relative compaction. In general, clayey soils should be compacted with sheepsfoot equipment and sandy/gravelly soils with vibratory equipment; open-graded materials such as crushed rock Ii! CORNERSTONE EARTH GROUP