4735 BAYVIEW LN 2025-10-09 - Laserfiche WebLink

4735 Bayview Lane Everet4 Washington Geotechnical Report The landforms in this portion of Snohomish County have formed over Pleistocene age glacial deposits. Deposits of glacial till, glaciomarine drift, gravel and sand from the last glaciation of the area overlie materials from earlier glacial and nonglacial episodes. The older deposits are exposed in sea cliffs and ravines along the shoreline of Puget Sound. The latest occurrence of glacial ice within the county is thought to have taken place during the later stages of the Pleistocene Epoch (some 11,000 years before present) and is referred to as the Vashon Stade of the Fraser Glaciation. Some 3500 feet of ice is thought to have overlain the area during this period. According to the Surficial Geology Map of the Mukilteo and Everett Quadrangles, by Mackey Smith, 1976, the area of the subject property is underlain by Vashon age glacial till deposits (Qvt) with Whidbey formation (Qw) deposits exposed in the sidewalls of the steep ravine on the east side of the site. All of these sediments have been consolidated to a dense condition by glacial ice that is thought to have been in excess of 3,500 feet thick in this area According to the Washington Interactive Geologic Map, Division of Geology and Earth Resources, the site is mapped as continental glacial drift deposits (likely till) and glacial and nonglacial deposits (likely Whidbey formation). Field Exploration In order to characterize the shallow soil and ground water conditions on the site a series of 5 exploration pits were excavated on the site with a subcontracted excavator on September 20, 2019. The pits generally encountered dense, brown, silty, fine to medium sand with gravel, cobbles and occasional boulders. Exploration pits EP-2 near the back of the existing house, and EP-5 near the center of the existing front yard area, also encountered silt and silty clay sediments. The silt in EP-2 was soft to a depth of 3.5 feet, then medium stiff to 4.5 feet then stiff with occasional gravel and cobbles to a depth of 6 feet. The silty clay in EP-5 was 30 inches thick and was underlain by the dense, silty, fine to medium sand with gravel and cobbles. In addition to the exploration pits we used a T-handle soils probe to probe the surficial soils at multiple locations around the site. In all instances, except adjacent to EP-2, probe refusal under full weight was observed within 24 inches of ground surface. Adjacent to EP-2 probing encountered about 3 feet of softer soils which agrees with the exploration pit findings. No standing or flowing water was observed on the property and no ground water was observed in any of the exploration pits excavated on the site. In addition, there were no hydrophilic (water loving) plants observed anywhere on the site. Our exploration confirms the published geologic mapping indicating Vashon age glacial till or glacial drift with till like aspects underlies the majority of the parcel. The silt and clay sediments are likely remnants of an old bog area that was reportedly (by a neighbor) located on the western portion of the property many years ago. Gary A. Flowers, PLLC 5205 23`tl Avenue W Everett, Washington 98203 206-819-4304