5900 36TH AVE W SEPA 015 - 034 - SOUNDVIEW BUSINESS CAMPUS - VERITAS Land Use Decision Documents 2025-04-22

3.0 WETLAND DETERMINATION 3.1 METHODOLOGY On -site wetland conditions were evaluated using routine methodology described in the 2010 Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0), (referred as 2010 Regional Supplement). The methodology in the 2010 Regional Supplement coincides with the methodology described in the Washington State Wetlands Identification and Delineation Manual (Washington State Department of Ecology Publication #96-94, March 1997, as required by the City of Everett. Under this method, the process for making a wetland determination is based on three sequential steps: 1) Examination of the site for hydrophytic vegetation (species presence and coverage); 2) If hydrophytic vegetation is found, then the presence of hydric soils is determined; 3) Determination of the presence of wetland hydrology in the area examined under the first two steps. 3.1.1 Vegetation Criteria The 2010 Regional Supplement defines hydrophytic vegetation as "the community of macrophytes that occurs in areas where inundation or soil saturation is either permanent or of sufficient frequency and duration to exert a controlling influence of the plant species present." Field indicators were used to determine whether the vegetation meets the definition for hydrophytic vegetation. 3.1.2 Wetland Soils Criteria and Mapped Description: The National Technical Committee for Hydric Soils, as described in the 2010 Regional Supplement, defines hydric soils as "a soil that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part." Field indicators were used to determine whether a given soil meets the definition for hydric soils. The soils underlying the site are mapped in the Soil Survey of Snohomish County Area Washington as Alderwood gravelly sandy loam, 2 to 8 percent slopes, Alderwood gravelly sandy loam, 15 to 25 percent slopes, and Alderwood-Everett gravelly sandy loam, 25 to 70 percent slopes. Alderwood gravelly sandy loam is described as a moderately well drained soil on till plains. It is moderately deep over a hardpan. This soil formed in glacial till. Typically, the surface layer is very dark grayish brown gravelly sandy loam about 7 inches thick. The upper part of the subsoil is dark yellowish brown and dark brown very gravelly sandy loam about 23 inches thick. Included in this unit are small areas of soils that have a stony of bouldery surface layer and areas of McKenna soils, Norma soils, and Terric Medisaprists in drainageways on plains. Also included are small areas of Everett, Indianola, and Ragnar soils on terraces and outwash plains. Included areas make up about 15 percent of the total acreage. Permeability of this soil is moderately rapid above the hardpan and very slow through it. Soils sampled on site appear similar to the description for Alder -wood gravelly sandy loam. Although Alderwood gravelly sandy loam is not Critical Area Study 4 WRI# 15202 Soundview Business Campus Rev. #2: October 2, 2015