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

12 water capacity is low. Effective rooting depth is 20 to 40 inches. Runoff is rapid, and the hazard of water erosion is high. A seasonal perched water table is at a depth of 18 to 36 inches from January to March. Springs or seep areas are common. The Everett soil is very deep and somewhat excessively drained. It formed in glacial outwash. Typically, the surface layer, where mixed to a depth of about 6 inches, is very dark grayish brown gravelly sandy loam. The subsoil is dark brown very gravelly sandy loam about 12 inches thick. The upper part of the substratum is brown very gravelly loamy sand about 5 inches thick. The lower part to a depth of 60 inches or more is dark brown extremely gravelly sand. Permeability of the Everett soil is rapid. Available water capacity is low. Effective rooting depth is 60, inches or more. Runoff is rapid, and the hazard of water erosion is moderate. This unit is used mainly as woodland and for wildlife habitat. It is also used for urban development. Douglas -fir is the main woodland species on the Alderwood soil. On the basis of a 100-year site curve, the mean site index is 142. On the basis of a 50-year site curve, the mean site index is 108. The mean annual increment at culmination (CMAI) for Douglas -fir at age 65 is 146 cubic feet per acre. Douglas -fir is the main woodland species on the Everett soil. On the basis of a 100-year site curve, the mean site index is 141. On the basis of a 50-year site curve, the mean site index is 111. The mean annual increment at culmination (CMAI) for Douglas -fir at age 65 is 1,46 cubic feet per acre. Among the trees of limited extent on this unit are western hemlock, western redcedar, and red alder. Among the common forest understory plants are salal, evergreen huckleberry, brackenfern, red huckleberry, common rose, and Oregon -grape. The main limitation for the harvesting of timber is steepness of slope. Slope restricts the use of wheeled and tracked equipment in skidding operations; cable yarding systems generally are safer and disturb the soils less. Harvesting systems that lift logs entirely off the ground reduce the disturbance of the protective layer of duff. Logging roads require suitable surfacing for year-round use. Rock for road construction is not readily available on this unit. Establishing plant cover on steep road cut and fill slopes reduces erosion. Steep yarding paths, skid trails, and firebreaks are subject to rilling and gullying unless adequate water bars are provided or they are protected by plant cover. Seedling mortality is the main limitation for the production of timber. Reforestation can be accomplished by planting Douglas -fir seedlings. If seed trees are present, natural reforestation of cutover areas by red alder occurs periodically. The high temperature and low moisture content of the Everett soil during the growing season cause high mortality of seedlings, especially Soil survey those on south- and southwest -facing slopes. When openings are made in the canopy, invading brushy plants, if not controlled, can.delay the establishment of seedlings. Because the rooting depth is restricted by a cemented pan in the Alderwood soil, trees are subject to windthrow. The main limitations of the Alderwood soil for septic tank absorption fields and homesites are steepness of slope and a seasonal perched water table. Effluent from absorption fields flows laterally above the pan and can seep at the bottom of slopes. Drainage is needed if buildings with basements and crawl spaces are constructed. This soil sloughs readily when saturated. The main limitations of the Everett soil for septic tank absorption fields are steepness of slope and seepage. If the density of housing is moderate to high, community sewage systems are needed to prevent contamination of water supplies as a result of seepage from onsite sewage disposal systems. Road cuts tend to slough readily. To protect the soils in this unit from erosion during construction, disturbed areas need. to be seeded and runoff should be controlled. This map unit is in capability subclass Vlle. 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. The average annual precipitation is about 40 inches, the average annual air temperature is about 50 degrees F, and the average frost -free season is 170 to 190 days. This unit is about 60 percent Alderwood gravelly sandy .loam and about 25 percent Urban land. The components of 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 plains. Also included are small areas of 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 of the total acreage. The Alderwood soil is moderately deep over a hardpan and is moderately well drained. It 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. 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 from 20 to 40 inches. Permeability of the Alderwood soil is moderately rapid above the hardpan and very slow through it. Available water capacity is low. Effective rooting depth is 20 to 40 inches. Runoff is slow, and the hazard of water erosion