3702 TULALIP AVE 2016-01-01 MF Import

� SERS Public Safe '-1-1 Communication Tower . r'SI Report No. 704-05224-5 Decei;;oer 23, 200C Page 5 the average of the upper 100 feet of soil. A ratio not greater than 5 percent critical damping should be used. If site-dependent earthquake response spectra or other specific design parameters are deemed necessary by the project structural engineer, or are required by the local govemmental agency who has jurisdiction over the project, the geotechnical engineer should be promptly infortned for further evaluation. 5.0 Conclusions and Recommendations Based on the results of our fieid work, laboratory evaluation, and engineering analyses, it is our opinion that the site is likely suitable for the proposed communication tower development provided the recommendations in the following sections are incorporated into the design and construction of the project. However, we were not able to explore the subgrade conditions in the vicinity of the western-most guy. We recommend that at least one backhoe test pit, or soil boring, be performed once access is provided to the guy footprint. 5.1 Site Preparetion In general, we recommend that all siructural improvement areas be drained of surface water, and stripped of topsoil, highly safurated or disturbed soil, loose fill soils, and any other deleterious materials encountered at the time of consiruction. Additional site preparation will depend upon the proposed site grades, weather conditions and tower features. rrior to placing any fill, all structural areas should be proofrolled under the observation of the geotechnical engineer with a fully loaded tandem axle dump truck or simiiar rubber tired vehicle. Soils that are observed to rut or deFlect excessively under the moving load should be undercut and replaced with properly compacted structural fill. After subgrade preparation and obseroation by the geotechnical engineer have been completed, fill placement may begin. The first iayer of fill shouid be placed in a relativaly uniform horizontai lift and be adequately keyed into the stripped subgrade soils. Fill materi�ls shouid be a well graded granular material free o(organic or other deieterious materials have a maximum particle size less than 3 inches, and fines with a liquid limit less than 45 and piasticity index less than 20. The on-site soils are �enerally considered to be suitable (or use as structurai fill, although they may require moisture conditioning prior to placement. All required structural fill materials should be moisture conditioned to within 3 percent of optimum moisture content �nd cornpacted by mechanical means to a minimum of 95 percent of the material's maximum dry density as determined in accordance with ASTM D 1557 (Modified