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603284-001 <br />The above section assumes Category 3 subgrade with good drainage <br />characteristics and an R-value of at least 30 compacted to at least 95 <br />percent relative compaction based on ASTM Test Method D 1557-10. <br />Representative samples of the actual subgrade materials should be <br />obtained and tested for R-Value following rough grading of the pavement <br />subgrade to confirm the pavement design sections. <br />5.8 Temporary Excavation and Shorinq Design <br />All temporary excavations, including utility trenches, retaining wall excavations <br />and foundation excavations should be performed in accordance with project <br />plans, specifications, and all OSHA requirements. Excavations 5 feet or deeper <br />should be laid back or shored in accordance with OSHA requirements before <br />personnel are allowed to enter. <br />No surcharge loads should be permitted within a horizontal distance equal to the <br />height of cut or 5 feet, whichever is greater from the top of the cut, unless the cut <br />is shored appropriately. Excavations that extend below an imaginary plane <br />inclined at 45 degrees below the edge of any adjacent existing site foundation <br />should be properly shored to maintain support of the adjacent structure. <br />Typical cantilever shoring should be designed based on the active fluid pressure <br />presented in Section 5.5. If excavations are braced at the top and at specific <br />design intervals, the active pressure may then be approximated by a rectangular <br />soil pressure distribution with the pressure per foot of width equal to 25H, where <br />H is equal to the depth of the excavation being shored. <br />During construction, the soil conditions should be regularly evaluated to verify <br />that conditions are as anticipated. The contractor should be responsible for <br />providing the "competent person" required by OSHA, standards to evaluate soil <br />conditions.Close coordination between the competent person and the <br />geotechnical engineer should be maintained to facilitate construction while <br />providing safe excavations. <br />5.9 Additional Geotechnical Services <br />The geotechnical recommendations presented in this report are based on <br />subsurface conditions as interpreted from limited subsurface explorations and <br />- 31 - <br />Leighton