9425 18TH AVE W 2018-01-01 MF Import

5—Alderwood-Urban land complex, 2 to 8 percent slopes. This map unit is on till plains. Areas are irregular in shape and are 100 to 1,000 acres in size. The native � vegetation is mainly conifers. Elevation is 50 to 550 feet. 7he average annual precipitation is about 40 inches, the average annual air temperature is about 50 degrees F, and the averzge frost-free season is 170 to 190 days. This unit is at�ou? 60 percent Alderwood gravelly sandy i loam and about 25 percent Urban land. The components of this unit are so intricately intermingled that it was not practical to map lhem separately at the scale used. Included in ti:is unit are small areas of McKenna and � Norma soils ar�d Terric Medisapnsts in depressional areas and drai �ageways on plains. Also included are small areas ol soils that are very shallow over a hardpan; small areas of Everett, Indianola, and Ragnar soils on terraces and outwash plains; and soils that have a stony and bouldery surtace layer. Included areas make up about 15 percent of the total ecreage. The Alderwood soil is rt�uderately deep over a hardpan and is moderately well drained. It tormed in glacial till. Typically, the surtace 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. The lower part is olive brown very gravelly sandy loam about 5 inches Ihick. A weakly cemented hardpan is at a depth of about 35 inches. Depth to the hardpan ranges from 20 to 40 inches. Permeability of the Aldenvood soil is moderately rapid above the hardpan and very slow through iL Available water capacity is low. Eftective rooting depth is 20 to 40 inches. Runoff is slow, and the hazard o( water erosion is slight. A seasonal perched water table is at a depth of 18 to 36 inches 'rom Januarv to March. Urban land is areas thai are covered by streets, buildings, parking lots, and other structures that obscure or alter the soils so that identification is not possible. The Alderwood soi! in this unit is used mainly for parks, building sites, lawns, gartlens, and v+oodland. The main limitations of the Alderwood soil for homesites and septic tank absorption fields are the depth to the hardpan and the seasonal perched water table. Onsite waste disoosal systems often fail or do nol (unction properly during periods of high rain(all. Drainage is needed if buildings with basements and crawl spaces are constructed. Topsoil needs to be stockpiled during site preparation and subsequently used to cover the exposed material. Additions of fertilizer and peat are desirable prior to seeding grass for lawns. This map unit is in capability subclass IVe. SCS SOILS DESCRIPTION "�