Geotechnical Investigation <br />Capital Hill PUD <br />Eugene, Oregon <br />If fill material derived from on-site excavations is to be used for the construction of roadway fill slopes the fill material <br />shall be sampled for Proctor testing and tested by nuclear densometer (ASTM 6938) periodically during placement to <br />ensure compliance with compaction standards, proper moisture conditioning will be required to maintain moisture <br />content within 2 percent of the material's optimum moisture content. It is not recommended to use on-site material as <br />fill during the wet season, generally October-May. Fill material for the construction of roadway subgrade shall be <br />compacted to a minimum of 95% relative compaction as determined by ASTM 698 (standard Proctor). Compacted <br />aggregate comprising the roadway structure base rock shall be compacted to 95% relative compaction as determined <br />by ASTM 1557 (modified Proctor). <br />Areas of Residential Foundations <br />On the ridgetop areas of the site and areas of relatively gentle slopes, conventional perimeter style foundations with <br />concrete foundation footings bearing of compacted aggregate placed on suitable subgrade are expected to be adequate. <br />As the steeper terrain on portions of the site is encountered during foundation excavation we anticipate that stepped <br />foundation with structural retaining walls in excess of 48-inches in height will be required. In these areas, the building <br />pad subgrade shall be excavated into suitable subgrade as described above and footings placed parallel to cuts shall <br />either be set back from the cut a distance equivalent to the height of the cut or structurally tied into walls installed at <br />the base of the cut with any remaining void spaced filled with compacted aggregate or open graded rock tamped into <br />place. <br />We anticipate that as structures are built on the lots within or adjacent to the area delineated as the "Area of <br />recommended exclusion for proposed construction of public or private streets and zone of special consideration for the <br />design and construction of residential foundations" as shown on Figure-1 that hillside foundation systems such as piers <br />or pilings will be required. Specific foundation plans within this area should be reviewed on a case by case basis by <br />qualified professionals prior to design and construction. <br />Table 1: <br />Recommended Construction Phases to be Observed by the Geotechnical Engineer <br />At completion of excavation to subgrade <br />Subgrade observation by the geotechnical engineer <br />before fabric and aggregate placement. <br />Imported fill material <br />Observation of material or information on material type <br />and source. <br />Observation by geotechnical engineer or test results by <br />Placement and Compaction of fill material <br />qualified testing agency. <br />Branch Engineering, Inc. <br />