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I I Soils Information The following soils information is copied from a scanned version of the text of the original Soil Survey report of Snohomish County Area,Washington issued July 1983. This information is available from the FRCS Washington state web site 111 www.wa.nrcs.usda.gov/index.html 1 4-Alderwood-Everett gravelly sandytoarns 25 depth of about inches, grayish brown 9 Y p 6 is very dark to 70 percent slopes. gravelly sandy loam.The subsoil is dark brown J This map unit is on till plains,terraces,and very gravelly sandy loam about 12 inches thick. outwash plains.Areas are 30 to 160 acres in size. The upper part of the substratum is brown very The native vegetation is mainly conifers and gravelly loamy sand about 5 inches thick.The hardwoods. lower part to a depth of 60 inches or more is dark Elevation is near sea level to 550 feet.The brown extremely gravelly sand. average annual precipitation is about 40 inches, Permeability of the Everett soil is rapid. the average annual air temperature is about 50 Available water capacity is low. Effective rooting I degrees F,and the average frost-free depth is 60 inches or more. Runoff is rapid, and the season is 170 to 190 days. hazard of water erosion is This unit is about 60 percent Alderwood moderate. gravelly sandy loam and about 25 percent Everett This unit is used mainly as woodland and for gravelly sandy loam.The components of this unit wildlife habitat. It is also used for urban I are so intricately intermingled that it development. was not practical to map them separately at the Douglas-fir is the main woodland species on scale used. the Alderwood soil.On the basis of a 100-year site I Included in this unit are small areas of Ragnar, curve,the mean site index is 142.On the basis of a Indianola,McKenna,and Norma soils and Terric 50-year site curve,the mean site index is 108.The Medisaprists in depressional areas and mean annual increment at ii drainageways on plains.Also included culmination(CMAI)for Douglas-fir at age 65 is 146 are colluvial soils,slump areas,and escarpments. cubic feet per acre. Included areas make up about 15 percent of the Douglas fir is the main woodland species on total acreage. the Everett soil.On the basis of a 100-year site 1 The Alderwood soil is moderately deep over a curve,the mean site index is 141.On the basis of a hardpan and is moderately well drained. It formed 50-year site curve,the mean site index is 111.The in glacial till.Typically,the surface layer is very mean annual increment at culmination(CMAI)for dark grayish brown gravelly sandy loam about 7 Douglas-fir at age 65 is 146 cubic feet per acre. inches thick.The upper part of the subsoil is dark Among the trees of limited extent on this unit yellowish brown and dark brown very gravelly are western hemlock,western redcedar,and red sandy loam about 23 inches thick.The lower part is alder.Among the common forest understory plants olive brown very are salal, evergreen I gravelly sandy loam about 5 inches thick.A weakly huckleberry,brackenfern, red huckleberry, cemented hardpan is at a depth of about 35 common rose,and Oregon-grape. inches.Depth to the hardpan ranges from 20 to 40 The main limitation for the harvesting of timber inches. is steepness of slope. Slope restricts the use of I Permeability of the Alderwood soil is wheeled and tracked equipment in skidding moderately rapid above the hardpan and very slow operations; cable yarding systems generally are through it.Available water capacity is low. Effective safer and disturb the soils less. I rooting depth is 20 to 40 inches.' Runoff is rapid, Harvesting systems that lift logs entirely off the and the hazard of water erosion is high.A seasonal ground reduce the disturbance of the protective perched water table is at a depth of 18 to 36 inches layer of duff. from January to March.Springs or seep areas. Logging roads require suitable surfacing for are common. year-round use. The Everett soil is very deep and somewhat Rock for road construction is not readily excessively drained. It formed in glacial outwash. available on this unit. Establishing plant cover on Typically,the surface layer,where mixed to a steep road cut and fill slopes reduces erosion. 11 I