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Project No. 1281 <br /> I IOct01 <br /> s.o s�T�E corrn�7�ior�s <br /> 5.1 Surface <br /> Asphalt-pavcd parking and a water quality/detention pond curently occupy t6e <br /> northeas�tem project :rci. A concrete sidewalk and adjacent SR 527 (19'� Ave. SE) <br /> bound the proje� arca to the east. SG ]04�' Stree�t and wetlands bound this aree to the <br /> south and we5�, respectively. <br /> 7'hc northr;astern project area contains two, adjacent detention pond cells. At the time of <br /> our visit, the cas�tem and western celis were, respectively, open and grown ove�• with <br /> cattails. fiach cell contained standing water. A chain link fence surroundeJ the detention <br /> pond and adjacent wetlanJ enhancement areas. Pond slopes showed no signs of <br /> sloughing or soil ins�tability. <br /> 'I'he southeastem project area lics partially within a fenced, wetland enhancement �rea <br /> adjacent to COS7'COs' southern access driveway and 1 G'� Avenue SG tumaround. A <br /> pond anJ sm.�ll creek lie north and east of the project area, respectively. The area of <br /> proposeJ constn�ction slopes gently to the cast and is densely vegetated with brush and <br /> variably sized deciduous trees. <br /> 5.2 Saas <br /> MPA ;�s�contracted I3oretcc, Inc. to complete three geotechnical borings fdesigarated I3-1 <br /> througi� C3-3) to depths rangino from 15.3 to 20.3 feet below exis�ting site grades. 'fhe <br /> boring logs with detailed Jescri�tinns of the soil and groundwater conditions are <br /> containcJ in Appendie A. 17�e approximate locations of the borings are shown on <br /> Figures 2A and 213. <br /> Soil samples were obtained at selected intervals within the borings in accordance with <br /> ASTM D 1586 test procedures. The samples were placed in sealed containers and taken <br /> to a laboratory. 'Pes�ts were performed on sclected samples in general accordance with <br /> AS'TM guiJclines to characteri-r�; engineering and index properties. These tests included <br /> Jetennination of natural moisture contents, and grain �ize dis1sibution� on 5 samples. <br /> The grain size distribution test results are attached as Appendi•: C. The moisiwe c�ntents <br /> are shown on the boring logs in Appendix A. <br /> I3-1 encountered fill soils comprised of loose to medium dense silty sand to a depth of 5.5 <br /> Ceet. Vcry dcnse becoming medium dense weathered till consisting of silty Sand with <br /> some gravcl undedies the fill to a depth of 15 feet. 'I'he very dense consistency of the <br /> upper portion of the weathered till in I3-1 indicates it was compacted during previous <br /> grading activities. [3-2 also shwved loose, weathered till to a Jepth ofabout 2 'ri feet. In <br /> both B-1 and 13-2, the weathered till soils were underlain by unweathered till comprised <br /> of very densc silty sand with gravel. The results of E3-2 is similar to GeoEngineers TP-2 <br /> and "I'P-9, which showed the weathered and unweathered till contact at a depth of 3 feet. <br /> f3-3 encountered very loose organic silty sand to a depth of about five fect. The organic <br /> soils are present at B-3 because of the close proximity of the adjacent wetland. Very <br /> Geotechnical and TurJ�el F� neers �r�\ <br /> 3050125°iAveNE � phme(425)869-5778 v <br /> Rcllewc.WA 98005 Pagc 3 Fmc (JIS)861-0677 <br />