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I I I I I I I I I I I I I I I I I I I Simons, Li and Associates, Inc, Job Number 6l43J002 Project Portland Flume Reconstruction is recommended that foundation excavations into undisturbed soils be inspected by the geotechnical engineer and deepened if loose or disturbed soils are encountered, If the soil conditions encount- ered are significantly different than those presented in this report, this firm should be contacted for verification and/or sup- plemental recommendations, Site Preparation: It is anticipated that excavation into the near surface soils should be possible with conventional excavation equipment. Excavation into areas with dense cobbles may possibly require heavy-duty, track-mounted excavation equipment with single-tooth rippers. Large boulders and sandstone bedrock will probably require over-excavation or the use of pneumatic operated jack-hammers or drills to facilitate rock break-up and removal, Since the material is a highly variable conglomerate, maximum par- ticle size and percentage will vary considerably along the align- ment of the flume. In general, maximum particle size will increase toward the top of the flume, The largest boulder size encountered in the test pits was 2 feet, but even larger sizes may be encountered during construction, Because the test pits were not excavated exactly on the alignment, some lenses or massive areas of underlying bedrock besides that observed in Test Pit No, 6 may be encountered, probably near the top of the flume, It should be anticipated that shoring of excavation side slopes will be required along some portions of the alignment, Areas of coarse granular material will require temporary lateral support as will areas where subsurface seepage is encountered, Groundwater was not encountered in the test pits, however, subsurface seepage may occur throughout the alignment and may vary depending on the time of year that construction takes place, -4- ~