1528 GRAND AVE Geotech Report 2022-10-25

GeoTest Services, Inc. Report Date 7/17/2019 Anderson Residence- Everett, Washington GTS Project No.19-0384 by the slope that is present on site less. It should not be interpreted that mitigation will eliminate any and all risk that might be present on the site. It is assumed that the property owner is adequately informed of the risk associated with the steep slope on this property, and that the recommendations in this report will be followed for the design and construction of the proposed addition. Seismic Hazards and Liquefaction Potential Liquefaction is the precipitous loss of shear strength experienced by loose, wet soils during cyclic loading (earthquakes). The risk of liquefaction-induced settlement is generally greater for saturated, granular soils compared to drier or finer-grained soils. The soils identified in our explorations were relatively dry, with the near-surface soils being loose. Notably, DCP data indicate an increase in density about 6 to 8 feet below the existing ground surface. Additionally, boring data from previous projects within several hundred feet of the subject property encountered groundwater at depths greater than 75 feet below existing site grades. For these conditions, the risk of liquefaction-induced settlement is low. The City of Everett Municipal Code (EMC) 19.37.080.A.2 specifically identifies seismically hazardous areas as those "mapped as seismic/liquefaction hazards per the Dames and Moore Methodology for the Inventory, Classification and Designation of Geologically Hazardous Areas, City of Everett, Washington [OR] those areas mapped as high and moderate to high liquefaction susceptibility on the Liquefaction Susceptibility Map of Snohomish County, Washington, Washington State Department of Natural Resources, Palmer, Stephen, et al., September, 2004." The Dames and Moore inventory does not classify the slope as a seismic hazard, and the referenced Washington DNR map classifies the project area as "very low" liquefaction susceptibility. Based on our review, no seismic/liquefaction hazard is present on the property, nor were any hazards identified per the EMC criteria. It is our opinion that mitigations to address seismic hazards or liquefaction are not required. Erosion The City of Everett Municipal Code (EMC) 19.37.080.A.3 states: "very high/severe erosion hazard areas include slopes of greater than forty percent in Qva and Qal geologic units." Given the predominately granular nature of the soils observed on site, the western portion of the property appears to constitute a "severe" erosion hazard 5