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Geotechnical Investigation ^ Proposed Courthouse Square - Salem, Oregon soils, thickness of potentially liquefiable soils, density of those soils and the overlying materials, depth that the soils occur, high ground water conditions, and potential seismic activity. Because fine sands occur in the stratigraphic profile and the seasonal ground water levels are relatively high, an assessment of the liquefaction potential was made. Based on subsurface conditions disclosed by the test borings, it is our opinion that the risk of liquefaction affecting the site is low. The geotechnical field investigation was limited by the presence of existing buildings on the site. Areas which were accessible at the time of our investigation generally included the northwest portion of the site and the southeast portion, representing approximately 50 percent of the overall area. Because of the lack of drill rig access, there is no geotechnical information available at this time for the remaining 50 percent of the site, currently occupied by the Senator Hotel in the southwest corner and county o~ces in the northeast corner. Geotechnical recommendations are based on information from the borings completed to date and our interpretation of geologic conditions across the site. It is important that additional borings are drilled, following demolition, in the areas which could not be accessed at the time of our investigation. Additional borings would be located to confirm expected uniform subsurface conditions and verify that no soft sand layers or other detrimental conditions occur which could impact the geotechnical design criteria. ~ ~ 7.0 RECOMMENDATIONS 7.1 Site Preparation , 1. Extensive ~ite~ demolition will be required, followed by excavation of the below ~ ground parking areas. In areas outside the excavations, remove all grasses, organic material, and any deleterious debris, such as asphalt, wood, or concrete rubble, from the construction area. 2. Remove all existing fill within the construction area. ~ 3. Previously unidentified old utility lines or water pipes, associated with the historical multi uses of the property, may exist on site following demolition. Any such features must be completely removed. ~ ~ ~~~ ~ centurywest ENGINEERING CORPORATION 'cJ March 7, 1997 40806.001.08 ~ ~