9205 4TH AVE W 2025-12-03 - Laserfiche WebLink

July 2, 2008 Duplex Buildings L&A Job No. 8AO67 Page 3 The site is currently vacant and undeveloped. It has been cleared previously and is over -grown with shrubs, brush and grass, with occasional tall mature trees scattered over the site. GEOLOGIC SETTING The Geologic Map of the Everett 7.5-Minute Quadrangle Snohomish County Washington, by James P. Minard, published by U. S. Geological Survey in 1985, was referenced for the geologic and soil conditions of the subject plat site. According to this publication, the surficial soil unit at and in the vicinity of the subject site is mapped as Vashon Till (Qvt). The geology of the Puget Sound Lowland has been modified by the advance and retreat of several glaciers in the past and subsequent deposits and erosion. The latest glacier advanced to the Puget Sound Lowland is referred to as the Vashon Stade of the Fraser Glaciation, which has occurred during the later stages of the Pleistocene Epoch and retreated from the region some 14,500 years ago. The Vashon till soil unit was plowed under the moving glacial ice during the most recent glacial period as it advanced over an eroded, irregular surface of older formations and sediments. It is composed of a mixture of unsorted clay, silt, sand, gravel, and scattered cobbles and boulders. The Vashon till soils over the top two to four feet are normally weathered to a medium -dense state, and is moderately permeable and compressible. The underlying fresh till soils are very dense, and are commonly referred to as "hard pan". The fresh till soils are practically impervious to stormwater infiltration. The fresh till soils possess the strength of low-grade concrete and can stand in steep natural slopes or man -make cuts for a long period. If remained undisturbed and well -drained, the fresh till soils can provide excellent foundation support to structures with little settlement expected. LIU & ASSOCIATES, INC.