9731 18TH AVE W 2018-01-02 MF Import

( 5—Alderwood-Urban land complex, 2 to B percent alopes. 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 teet. The average annual precipitation is about 40 inches, the average annuai air temperature is about 50 degrees F, and the average frost•free season is 170 to 190 days. This unit is about 60 percent Aldenvood gravelly sandy loam and about 25 percent Urban land. The components ol this unit are so intricately intermingled that it was not practical to map them separately at the scale used. Included in this unit are small areas of McKenna and Norma soils and Terric Medisaprists in depressional areas and drainageways on piains. Also included are small areas oi 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 surface layer. Included areas make up about 15 percent ot the total acreage. The Aldenvood soil is mcderately deep over a hardpan and is moderately well drained. It iormed in glacial till. Typically, ihe surface layer is very dark grayish brown gravelly sandy loam about 7 inches thick. The upper part of the subsoil is dark yellowish browr� and dark brown very gravelly sandy loam about 23 inches tl�ir.k. The lower part is olive brown very gravelly sandy loam about 5 inches thick. A weakly cemented hardpan is at a depth of about 35 inches. Depth to the hardpan ranges irom 20 to 40 inches. Permeabiliry of the Alderwood soil is moderately rapid above the hardpan and very slow through it. Available water capacity is low. ENective rooting depth is 20 to 40 inches. RunoH is slow, and the hazard of water erosion is slight. A seasonal perched water table is at a depth of 18 to 36 inches from January to March. Urban land is areas lhat are covered by streets, buildings, parking lots, and othar structures that obscure or alter the soils so that identitication is not possib!e. The Alderwood soil in this unit is used mainly for parks, building sites, lawns, gardens, and woodland. The main limitations ot the Alderwood soil for homesites and septic tank absorption tields are the depih to the hardpan and the ,easonal perched water tatr�e. Onsite waste disposal aystems oflen fail or do not iunction properly during periods of h�gh raintall. Drainage is needed ii buildings with basemen!s 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 tor lawns. This map unit is in capability subclass iVe. SCS SOILS DESCRIPTION i