5221 23RD AVE W 2023-04-10 - Laserfiche WebLink

410 I September 10, 2021 G-5535 Geological Assessment Letter Page 3 5221 23rd Avenue W,Everett, Washington assessment letter. The critical areas present near the project site are illustrated in Plate 3 — Critical Areas Mapping. On September 7, 2021, we visited the above-subject property and conducted a site reconnaissance of the potential landslide hazard area located in the adjacent east property and evaluated whether the proposed new deck will cause adverse impacts to the hazards. During our site reconnaissance,we observed that the area of the deck is located on relatively flat topography and its required construction area will be located more than 50 feet from the east property line and about 100 feet from the edge of the high to very high-susceptibility landslide hazard area. We observed that the dense vegetation and trees within the slope appeared mature and vertically grown without evidence of shallow or deep-seated historic ground movement. The soils present near the surface of the slope appeared to be native, gray fine-grained sands consistent with the Vashon till mapped at the property. We probed throughout portions of the slope using a 0.5-inch diameter probing rod and reached depths of about 10 to 18 inches before encountering medium dense to dense soils. We did not locate water springs or seepage in the vicinity of the above- subject property, and drainage pipes were present and appeared to be used to discharge water towards the bottom of the ravine. Based on the conditions encountered in our site reconnaissance and settlement evaluation, it is our opinion that the project plans are presented and described above are in general conformance with the criteria in the Minimum Standards for Geological Assessments of 19.37.073 of the Everett Municipal Code(EMC). In our opinion and in compliance with EMC 19.37.073.B.1.a, it is our opinion that no active geologically hazardous area exists on or within 200 feet of the project site. We evaluated the proposed work area and the sections of the steep slope and potential landslide hazard area within 200 feet of the east perimeter of the new deck's work area and did not observe evidence of historic soil movement, slope instability,water seepage, or other conditions that would suggest that the site conditions would be adversely impacted by the earthwork associated with the new deck foundations. In our opinion,the new deck foundations will not impose surcharge loads at the upper contours of the landslide hazard area as the east perimeter of the deck is greater than 50 feet from the top of the landslide hazard area. Based on the dimensions of the new deck and the conditions we encountered at the site and within the landslide hazard area, it is our opinion that the potential impact of the proposed development activity within the 200-foot buffer of the high-susceptibility landslide area will be minimal. It is our opinion that the development buffer from the landslide GEO Group Northwest,Inc.