3617 UPLAND AVE Geotech Report 2025-03-28

GeoTest Services, Inc. April 15, 2021 3617 Upland Avenue, Everett,WA Project No. 21-0375 The steep slope bisecting the property is classified to be "very high risk" per the EMC due to the underlying soils consisting of either Transitional Beds or previously placed, uncontrolled fill. We did not observe any noticeable signs of instability on this slope during our visits to the subject property. It appears that these slopes were created due to previous grading on the property when the original residence was constructed in 1937, or for previous grading for the existing roadways (Geyer Lane and Upland Avenue). Due to past grading as an engineered slope and observed performance since the grading occurred, combined with the limited slope height, it is GeoTest's opinion that this slope is not a landslide hazard. The proposed residence will have a daylight basement, of which the southern portion of the house foundation will be embedded into the existing slope. This portion of the house foundation would be designed as both a foundation and retaining wall. Apart from the excavation for the proposed residence, the existing slope would not be altered as part of the new development. It is therefore GeoTest's opinion that the construction of the proposed residence would not adversely affect the stability of the existing slope, provided that the recommendations in this report are followed. CONCLUSIONS AND RECOMMENDATIONS Based on the evaluation of the data collected during this investigation, it is our opinion that the subsurface conditions at the site are suitable for the proposed development, provided the recommendations contained herein are incorporated into the project design. Subsurface explorations exposed in this study encountered approximately 1 foot of loose topsoil before encountering loose to medium-dense fill soils. Native, medium-dense Transitional Beds were encountered at an approximate depth of 2.5 to 7 feet BGS. It appears that the thicker depths of fill were encountered in the explorations performed in the southwest, upslope portion of the subject property. Proposed Residence As the proposed residence on the newly created lot will include a daylight basement, GeoTest anticipates that approximately 2 to 6 feet (or more) of excavation to remove the loose, near- surface fill soils and to reveal competent bearing soils (native,Transitional Beds)for the proposed house foundations. The proposed depth of excavation will depend on the proposed basement elevation, of which preliminary information was not available as of the writing of this report.The depth of required excavation would decrease towards the northern portion of the proposed house footprint. Once bearing soils have been revealed in the proposed house footprint, we recommend that the native subgrade be recompacted to a firm and unyielding condition. The proposed residence can then be constructed with conventional continuous or individual spread foundations bearing directly on firm and unyielding native soils, or on compacted structural fill placed atop these soils. 5