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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 />611J A X6191JA I I§ 1401,14 iYA DI rl Y 119100 td X@11 X83:1011q W-14 a9 [d :&1 <br />GeoEngineers should be retained to review the project plans and specifications when complete to confirm <br />that our design recommendations have been implemented as intended. <br />During construction, GeoEngineers should observe subgrade preparation for foundations and floor slabs, <br />observe installation of subsurface drainage measures, evaluate structural fill and trench backfill, evaluate <br />pave ment/ha rdsca pe subgrade, and provide a summary letter of our construction observation services. <br />The purposes of GeoEngineers' construction phase services are to confirm that the subsurface conditions <br />are consistent with those observed in the explorations and other reasons described in Appendix C, Report <br />Limitations and Guidelines for Use. <br />6.0 LIMITATIONS <br />We have prepared this report for the exclusive use of LMJ Enterprises and their authorized agents for the <br />Lee Johnson Dealership Hyundai Dealership Redevelopment site in Everett, Washington. <br />Within the limitations of scope, schedule and budget, our services have been executed in accordance with <br />generally accepted practices in the field of geotechnical engineering in this area atthe time this report was <br />prepared. No warranty or other conditions, express or implied, should be understood. <br />Please refer to Appendix C for additional information pertaining to use of this report. <br />7.0 REFERENCES <br />Idriss, I.M. and Boulanger, R.W., 2014. "CPT and SPT Based Liquefaction Triggering Procedures. <br />International Code Council, 2018. "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 />GEOENGINEER� December6, 2021 Page 12 <br />File No. 24 59-003-00 <br />