917 112TH ST SE Geotech Report 2022-10-25

Habitat for Humanity of Snohomish County ES-5168 April 26, 2017 Page 4 Groundwater Groundwater seepage was encountered at the time of our subsurface exploration at test pit locations TP-1, TP-3, and TP-4 at depths of approximately three to five feet bgs. The presence of groundwater seepage should be expected in excavations, especially in a perched condition at the contact between the upper weathered till and underlying unweathered till soils. Groundwater seepage rates and elevations fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater elevations and flow rates are higher during the winter, spring and early summer months. Geologically Hazardous Areas As part of this study, the subject site and surrounding area were evaluated for the presence of geologically hazardous areas. As part of our evaluation, Chapter 19 of the Everett Municipal Code (EMC) was reviewed as well as critical area maps provided by the City of Everett. Based on the results of our study, no geologically hazardous areas are located within or adjacent to the subject property. DISCUSSION AND RECOMMENDATIONS General Based on the results of our study, the proposed structures can be supported on conventional spread and continuous foundations bearing on undisturbed competent native soil, recompacted native soil, or new structural fill. Competent soils suitable for support of foundations should be encountered beginning at depths of about two to three feet below existing grades across the majority of the site. Slab-on-grade floors should be supported on dense native soil, re- compacted native soil, or new structural fill. Organic material exposed at subgrade elevations must be removed below design elevation and grades restored with structural fill. Where loose, organic or other unsuitable materials are encountered at or below the footing subgrade elevation, the material should be removed and replaced with structural fill, as necessary. This study has been prepared for the exclusive use of Habitat for Humanity of Snohomish County and their representatives. No warranty, expressed or implied, is made. This study has been prepared in a manner consistent with the level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. Site Preparation and Earthwork Initial site preparation activities will consist of installing temporary erosion control measures, establishing grading limits, and performing site clearing and site stripping (as necessary). Subsequent earthwork procedures will involve mass grading and related infrastructure improvements. Earth Solutions NW, LLC