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

The lowlands, having been recently scoured by the Puget Lobe, filled readily. The remaining ice was lifted and rapidly melted as berg ice (Easterbrook 2003). The modern landform is characterized primarily by deposits of glacial till with inclusions of hydric soils associated with glacial runoff. With the exception of minor fluctuations, which can be attributed to extensive land clearing during the nineteenth and twentieth centuries, the ecological landscape surrounding the APE has been relatively stable (Leopold et al. 1982). The topography of the site is a generally northern aspect; the southwestern corner of the APE slopes steeply down to Japanese Gulch. There is a forested, defined wetland mosaic in the southeast corner of the site, as well as a disturbed Category III wetland area within the central portion of the property. The level portion of the project APE has been clear-cut within the past 10-12 years and has been replaced over time with dense early successional alder (Alnus rubra) and Himalayan blackberry (Rubus sp.) growth. Soil Survey Soils mapped within the APE consist of Alderwood gravelly sandy loam in the western and central portion and Alderwood-Everett gravelly sandy loam, 25-70 percent slopes, in the southeastern portion of the project area (MRCS 2014). The Alderwood series consists of moderately deep poorly drained soils formed over hardpan. The soils are comprised of glacial till. A typical profile has a 18-cm-deep (7-inch-deep) A horizon of very dark grayish brown, ashy, gravelly sandy loam; a B horizon (Bw1, Bw2, Bg) from 18-89 cm (7-35 inches) of yellowish brown, dark brown, and olive brown very gravelly, ashy sandy loam containing areas of McKenna, Norma, and Medisaprists soils; and a C horizon (2Cd1, 2Cd2) from 89-152 cm (35-60 inches) of dark grayish to grayish brown gravelly sandy loam (MRCS 2014). Alderwood soils are moderately well drained and acidic (pH 5.8 to 6.0); the perched water table above the densic layer is highest from January through March. Native vegetation would have been predominantly red alder (Alnus rubra), western red cedar, big leaf maple (Ater macrophyllum), western hemlock, and Douglas fir, with an understory of salal (Gaultheria shallon), Oregon grape (Mohonia nervosa), western bracken fern (Pteridium aguilinum), western swordfern (Polystichum munitum), Pacific rhododendron (Rhododendron macrophyllum), huckleberry (Vaccinium spp.), and orange honeysuckle (Lonicera ciliosa) (MRCS 2014). The Alderwood-Everett series is similar to the Alderwood series. Everett soils are on glacial outwash terraces, terrace escarpments, drift plains, and moraines. A typical profile has a very thin Oi horizon of decomposing plant material over a narrow (5-cm [2-inch]) A horizon. The cambic (Bw) horizon is a 50.0-cm (19.7-inch) layer of decomposing parent material (MRCS 2014). Everett series soils have a strongly acid pH of 5.3 in the A horizon; the Bw horizon moves from a strongly acid pH of 5.5 in the upper layer to a moderately acid pH of 5.6 in the deeper layers. These soils formed under natural vegetation such as red alder, western red cedar, western hemlock, and Douglas fir, with an understory of salal, western swordfern, oceanspray (Holodiscus discolor), and Oregon grape. CULTURAL CONTEXT The determination of the probability for historic properties to be located within the APE was based largely upon review and analysis of past environmental and cultural contexts and previously documented cultural resource studies and sites. Consulted sources included project files; local geologic data to better understand the depositional environment; archaeological, historic, and Tierra Archaeological Report No. 2014-077