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4.8. Stormwater Infiltration <br /> Given the low permeability of glacial till deposits at the site, stormwater infiltration rates will likely be very <br /> low. We recommend a preliminary long-term design infiltration rate of not more than 0.1 inches per hour <br /> be used for preliminary design of infiltration facilities located in the native glacial till deposits at the site. <br /> If infiltration is being considered, we recommend that on-site pilot infiltration tests (PITs) be performed to <br /> determine infiltration design criteria. <br /> 5.0 RECOMMENDED ADDITIONAL GEOTECHNICAL SERVICES <br /> GeoEngineers should be retained to review the project plans and sl:_ri m mcations when complete to confirm <br /> that our design recommendations have been implemented as in : :Jed. <br /> During construction, GeoEngineers should observe subgraac ;jreparatu n for foundations and floor slabs, <br /> observe installation of subsurface drainage measures, evaluate structure,, Fill and trench backfill, evaluate <br /> pavement/hardscape subgrade, and provide a summary letter of our cons!, . tion observation services. <br /> The purposes of GeoEngineers' construction phase services are to confirm that subsurface conditions <br /> are consistent with those observed in the exploration:: I id other re:a ons describe,i in Appendix C, Report <br /> Limitations and Guidelines for Use. <br /> 6.0 LIMITATIONS <br /> We have prepared this report for the exclusive ,:se of LMJ Enterprises lc i 1 their authorized agents for the <br /> Lee Johnson Dealership f-ly ,rdai Dealership Redovelopment site in Everett, Washington. <br /> Within the limitations of s,;ope, sched!.alr and budges, our services have been executed in accordance with <br /> generally accepted practices i r I the field of geotechnic_II engineering in this area at the time this report was <br /> prepared. No warranty or othei e,:raress or implied, should be understood. <br /> Please refer to Appendix C for additional informationp, taining to use of this report. <br /> 7.0 REFERENCES <br /> Idriss, I.M. and Boulano r, R.W., 2014. "CPT and SPT Based Liquefaction Triggering Procedures." <br /> International Code Council, `'1)1' International Building Code." <br /> Ishihara, K., and Yoshimine, M., 1992. "Evaluation of Settlements in Sand Deposits Following Liquefaction <br /> During Earthquakes," Soils and Foundations, 32(1), pp. 173-188. <br /> Rocsience, 2016, Settle3D v. 4.0. <br /> Tokimatsu, K. and Seed, H.B., 1987. "Evaluation of Settlements in Sands Due to Earthquake Shaking," <br /> Journal of Geotechnical Engineering, ASCE, 113(GT8), pp. 861-878. <br /> GEOENGINEERS December 6,2021 Page 12 <br /> File No.24459-003-00 <br />