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Geotechnical Investigation ^ Proposed Courthouse Square - Salem, Oregon C ~~ ~ ~~ ~ ~ ~ ~ ~ i ;} ~J the soil by dropping a 140-pound hammer through a free fall of 30 inches. The number of blows required to drive the sampler into the soil is known as a penetration test. The number of blows required for the sampler to penetrate 12 inches gives an indication of the consistency or relative density of the soils encountered. Results of the penetration tests (N-Values) aze shown on the Boring Logs presented in Appendix A. Borings were logged, at the time of drilling, by a Century West Engineering geologist. Boring depths were generally 40 feet. Samples collected from the upper 15 feet of each boring were collected under environmental sampling protocol and were taken to Century Testing Laboratories in Bend, Oregon for analysis. Environmental site characterization will be presented in a separate report. 4.0 LABORATORY TESTING Samples were returned to the soils and materials laboratory where they were visually classified. Testing was then completed on representative samples. Because of the granular nature of the samples, testing was limited to gradation analyses and moisture content. All testing was done in accordance with current ASTM standards. Results of the laboratory testing are presented on the test data sheets in Appendix B of this report. 5.0 SUBSURFACE CONDI't'IONS The exploratory borings drilled within the accessible areas of the project site indicate that the property is underlain by river alluvial deposits. These deposits consist of coazse grained, dense silty gravels extending to a depth varying from 10 to 20 feet, underlain by dense sandy gravels. Below a depth of 30 to 35 feet, in part of the site (B-3, B-13, B-25), a 10 foot thickness of more sandy materials existed, These materials varied from dense sand deposits, to zones of dense sandy gravel interlayered with thin sand lenses. In Boring 25, located in the southeast corner of the site, a 4-foot thick layer of loose sand was encountered from 39 to 43 feet below ground surface. The only fill encountered on the site was located at the former service station site in the southeast corner of the property. Fill at that location was 13 feet thick. . :~~ ~ centurywest ENGINEERING CORPORATION March 7, 1997 40806.001.09 ~ ' 3