Laserfiche WebLink
~ Geotechnical Investigation <br />t . ^' <br />Proposed Courthouse Square - Salem, Oregon <br />4. Any existing foundations or basement walls shall be completely removed within the <br />~ construction area. <br />5. All excavation caused from demolition or subsequent removals shall be back-filled <br />and compacted to the minimum degree of compaction specified below for general <br />~ fill. Where such excavations are greater than 5 feet in depth, the sides of the <br />excavation shall be laid back and the fill benched into native soils. <br />7.2 Excavation <br />~ l. The surface layer of silty gravels is considered moderately stable in open <br />excavations. For the purpose of determining allowable excavation slopes, the OR- <br />~ OSHA soil classification is Type B. These materials typically vary in thickness from <br />[ i'~ 10 to 20 feet. ~ <br />2. Sandy gravel materials underlie the surface silty gravels. Although these materials <br />have high confined strength, in an open excavation the cohesionless materials will <br />be subject to caving and sloughing. For the purpose of determining allowable <br />excavation slopes, the OR-OSHA soil classification is Type C. These materials <br />generally extend to the bottom of proposed excavations. Some form of shoring or <br />bracing should be anticipated to maintain stability of excavations in these materials. <br />3. An OR-OSH~'designated Layered Soil condition should be considered to exist <br />across the site. <br />4. A dewatering plan should consider that the subsurface materials have a generally <br />high porosity and permeability. The estimated values in the table below are <br />considered representative of the materials present. Potential ground water velocities <br />in these granulaz materials may make excavation dewatering quite difficult. <br />~ <br /> ~~~ <br />~ <br />~ centurywest <br /> EN6INEERING CORPORATION <br /> March 7, 1997 40806.001.08 <br />~ <br />6 <br />~ <br />