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Geotechnical Investigation Report Detroit Lake Water Reservoir Detroit, Oregon D.1.3 Trench Backfill Pipe bedding placed to uniformly support the barrel of pipe should meet specifications provided in ODOT SS 00405.12 – Pipe Zone Bedding. The pipe zone that extends from the top of the bedding to at least 8-inches above utility lines should consist of material prescribed by ODOT SS 00405.13 – Pipe Zone Material. The pipe zone material should be compacted to at least 90 percent of the maximum dry density, as determined by ASTM D 1557, or as required by the pipe manufacturer. Within roadway alignments or beneath building pads, the remainder of the trench backfill should consist of well-graded granular material with less than 10 percent by weight passing the U.S. Standard No. 200 Sieve, and should meet standards prescribed by ODOT SS 00405.14 – Trench Backfill, Class B or D. This material should be compacted to at least 92 percent of the maximum dry density, as determined by ASTM D 1557, or as required by the pipe manufacturer. The upper 2 feet of the trench backfill should be compacted to at least 95 percent of the maximum dry density, as determined by ASTM D 1557. Controlled low strength material (CLSM), ODOT SS 00405.14, Class E, can be used in lieu of above. Outside of structural improvement areas (e.g., roadway alignments, sidewalks or building pads), trench material placed above the pipe zone may consist of general structural fill materials that are free of organics and meet ODOT SS 00405.14 – Trench Backfill, Class A. This general trench backfill should be compacted to at least 90 percent of the maximum dry density, as determined by ASTM D 1557, or as required by the pipe manufacturer or local jurisdictions. D.1.4 Stabilization Material Stabilization rock should consist of pit or quarry run rock that is well-graded, angular, crushed rock consisting of 4- or 6-inch-minus material with less than 5 percent passing the U.S. Standard No. 4 Sieve. The material should be free of organic matter and other deleterious material. ODOT SS 00330.16 – Stone Embankment Material can be used as a general specification for this material with the stipulation of limiting the maximum size to 6 inches. D.1.5 Soil Amendment with Cement As an alternative to the use of select granular backfill material for wet-weather structural fill, an experienced contractor may be able to amend the on-site soils with portland cement or with limekiln dust and cement to obtain suitable support properties. Successful use of amendments depends on the use of correct mixing techniques, soil moisture content, and amendment quantities. Specific recommendations for soil amending (based upon exposed site conditions) can be provided, if necessary. Portland cement-amended soils are hard and have low permeability. Therefore, these soils do not drain well, nor are they suitable for planting. Future planted areas should not be cement amended, if practical, or accommodations should be planned for drainage and planting. D.1.6 Retaining Wall Backfill Backfill material placed behind retaining walls and extending a horizontal distance of ½H, where H is the height of the retaining wall, should consist of granular material meeting ODOT SS 00510.12 which recommends ODOT SS 02630.11 – Open-Graded November 23, 2009 Project No. 72852.000 D-2