1910 W MUKILTEO BLVD Geotech Report 2022-10-25

� F Geotechnical Engineering EvalLIOn NGA File No.1238721 Spencer Garage Addition February 11,2021 Everett,Washington Summary-Page 2 Final stormwater plans have also not been developed, but we understand that on-site infiltration is being considered for this site.The subsurface soils generally consisted of surficial topsoil/undocumented fill soils underlain by granular fine to coarse sand with varying amounts of silt, gravel and iron-oxide weathering that we interpreted as native transitional beds soils at relatively shallow depths. Based on our infiltration testing and silty nature of the onsite native soils encountered at depth throughout the site, it is our opinion that stormwater infiltration is not feasible within the site. Alternative stormwater management options should be considered. In the attached report, we have also provided general recommendations for site grading, slabs-on- grade, structural fill placement, erosion control, and drainage. We should be retained to review and comment on final: development plans and observe the earthwork phase of construction. We also recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed differ from those anticipated,and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. It has been apleasure toprovide service toyou on this project. Please contact-us if you have any questions regarding this report or require further information. Sincerely, NELSON GEOTECHNICAL ASSOCIATES,INC. Khaled M.Shawish, PE Principal Engineer