5230 EAST DR 2022-02-01 - Laserfiche WebLink

b COBALT GEOSCIENCES GEOTECHNICAL INVESTIGATION EVERETT, WASHINGTON December 5, 2019 5.1.2 Groundwater Groundwater was not encountered in any of the explorations. There is a chance that perched groundwater may be encountered during late winter and early spring months. We anticipate that groundwater would be perched between fill or weathered till and underlying unweathered glacial till. Water table elevations often fluctuate over time. The groundwater level will depend on a variety of factors that may include seasonal precipitation, irrigation, land use, climatic conditions and soil permeability. Water levels at the time of the field investigation may be different from those encountered during the construction phase of the project. 6.o Geologic Hazards 6.1 Landslide Hazard The site and adjacent areas contain areas with slopes greater than 40 percent and relief of at least io feet. The ravines west and north of the property, have topographic relief of about 25 to 5o feet with slopes up to 6o percent magnitude. Relevant items with our comments from the City of Everett Municipal Code are below. Items that pertain to the site are highlighted with our discussion in italics. 19.37.o8o Geologically hazardous areas. A. Designation. Except for geologically hazardous areas regulated by the shoreline master program, the following geologically hazardous areas shall not be altered except as otherwise provided by this chapter: 1. Landslide hazard areas: a. Those areas defined as high and very high/severe risk of landslide hazard in the Dames and Moore Methodology for the Inventory, Classification and Designation of Geologically Hazardous Areas, City of Everett, Washington: July 1, 1991: i. Very high/severe: slopes greater than fifteen percent in the Qtb, Qw, and Qls geologic units; and slopes greater than fifteen percent with uncontrolled fill. _. w ' and Qls or ii. High slopes greater, than forty percent in all other geologic units (not Qtb, Q , uncontrolled fill) b1.. Those areas defined as medium risk of landslide hazard in the Dames and Moore Methodology for Inventory, Classification and Designation of Geologically Hazardous Areas, City of Everett, Washington: July 1, 1991, when combined with springs or seeps, immature vegetation, and/or no vegetation: i. Slopes less than fifteen percent for Qtb, Qw, and Qls geologic units and uncontrolled fill. Ji, .Slopes.of twenty-five p.ercent_to.:forty .percent.in.all.other geologic units. c. Any area with all three of the following characteristics: i. Slopes greater than fifteen percent; and 3 PO Sox 82243 Kenmore, WA 98028 wbaltgeo@gmail com 2o6-331-1097