Appendix E - Geology and Soils Geotechnical Supporting Information COMBINED

LESTER-SHRINER PROPERTY 132-8-2 Page 14 6.3 REMOVAL OF EXISTING FILLS While undocumented fills were not encountered in the previous explorations, artificial fills (including previous test pit backfill) encountered during site grading should be over-excavated and replaced as engineered fill. All fills should be completely removed from within building areas and to a lateral distance of at least 5 feet beyond the building footprint or to a lateral distance equal to fill depth below the perimeter footing, whichever is greater. Provided the fills meet the “Material for Fill” requirements below, the fills may be reused when backfilling the excavations. If materials are encountered that do not meet the requirements, such as debris, wood, trash, those materials should be screened out of the remaining material and not be reused. Backfill of excavations should be placed in lifts and compacted in accordance with the “Compaction” section below. 6.4 ROCK EXCAVATION Based on the previous field exploration and our experience in the vicinity, in our opinion, the bedrock that underlies the site can likely be excavated with conventional construction equipment such as a Caterpillar D9 bulldozer. The excavation characteristics of the bedrock will be dependent on such properties as rock type, the degree of weathering, the orientations of bedding planes and joints, and the strength of properties of the material. The previous investigation recorded bedrock shear wave velocities during the seismic refraction survey that ranged from approximately 1,300 to 8,900 feet per second. The shear wave velocities indicate soft to moderate ripping is likely within the upper approximately 15 to 20 feet, while moderate to hard ripping is likely below 20 feet. The prior rippability assessment presented by Lowney Associates was reportedly based on information published in the Caterpillar Performance Handbook. It should be noted that some resistant beds of sandstone may be encountered locally that will be very difficult to excavate with conventional equipment and may require the use of very heavy single-tooth ripping with a Caterpillar D10, or hydraulic jacking and hammering. We recommend that local grading contractors experienced in rock excavation methods be contacted to aid in determining the efficiency, time and costs associated with the proposed cuts. It should be noted that seismic refraction survey is considered to have an accuracy range of plus or minus 20 percent. Seismic layers do not always correspond directly to lithology changes that might be found in boreholes or trenching data. Care should be used in estimating bedrock rippability at depths greater than 20 to 25 feet. If desired, a more detailed seismic refraction survey could be performed during the design-level geotechnical investigation to determine shear wave velocities at deeper depths. Since additional excavation for utilities will he required in roadway areas, it may he desirable to over- excavate the road subgrade and replace with compacted fill. This may reduce excavation costs during storm drain, sewer, and joint trench installation. The depth of the over-excavation in roadway areas would likely be on the order of 5 to 6 feet and will depend on the required utility depths. Prior to over-excavating the roadway, it may be feasible to pot-hole with conventional backhoe equipment once the roadway subgrade has been exposed to determine if over- excavation would be appropriate. Ii! CORNERSTONE EARTH GROUP