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Geotechnical Investigation <br />^ <br />Proposed Courthouse Square - Salem, Oregon <br />Soil Type Permeability <br />Silty gravel with some sand: 1 x 10'3 cm/sec <br />Surface layer <br />Sandy gravel: 10'Z to 10-3 cm/sec <br />May occur near bottom of excavation <br />7.2 General Grading <br />1. Import soils shall be granular in nature, and shall be approved by the Geotechnical <br />Engineer prior to transporting to the site. <br />2. Fill material shall be free of organic matter, debris, and any rocks or chunks over 3- <br />inches in maximum dimension, unless otherwise specified and approved by the <br />Geotechnical Engineer. <br />3. All native soils shall be scarified and compacted prior to placement of fill. Scarified <br />soils should be compacted to a minimum relative compaction of 95 percent of <br />maximum density as determined by ASTM D-1557 (Modified Proctor). <br />4. Scarification of soils shall be accomplished by ripping at intervals no further apart <br />than 18 inches.' <br />5. Fill material shall be placed at a moisture content which will allow adequate <br />compaction. This is normally within three percent of optimum. <br />6. All general fill shall be compacted to a minimum relative compaction of 95 percent <br />of m~imum density as determined by ASTM D-1557 (Modified Proctor). Field <br />density tests shall be made in conformance to ASTM D-1556 or D-2922. <br />- 7. Backfill of utility trenches shall be done with on-site material or clean granular <br />import fill and compacted to 95 percent of maximum density. Outside of structural <br />~ areas, utility trench backfill may be compacted to 90 percent of maximum density. <br />~ <br />~~~ ' <br />~ centurywest ~ ~ <br />ENGINEERING CORPORATION 7 <br />March 7, 1997 40806.001.08 <br />~ <br />~ <br />