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12 Soil survey <br /> water capacity is low. Effective rooting dew is 20 to 40 those on south-and southwest-fa • g slopes.When <br /> inches.Runoff is rapid,and the hazard a water erosion openings are made in the can , invading brushy <br /> is high.A seasonal perched water r,f- is at a depth of plants,if not controlled, elay the establishment of <br /> 18 to 36 inches from January to •arch.Springs or seep seedlings. Because the ling depth is restricted by a <br /> areas are common. cemented pan in the derwood sod, trees are subject to <br /> The Everett soil is ve .eep and somewhat windthrow. <br /> excessively drained. armed in glacial outwash. The main lim 'ens of the Alderwood soil for septic <br /> Typically,the r e layer,where mixed to a depth of tank absorp• fields and homesites are steepness of <br /> about 6 in ' --. very dark grayish brown gravelly sandy slope seasonal perched water table. uent from <br /> loam.The _.1.-a. is dark brown very gravelly sandy loam ' n fields flows laterally above - a-n and can <br /> about 1- riches thick.The upper part of the substratum at the bottom of slopes Drain-:- is needed if. <br /> is bra n very gravelly loamy sand about 5 inch.--thick dings with basements and Cr spaces are <br /> - lower part to a depth of 60 inches or ma•- is dark constructed.This soil sloughs dily when saturated. <br /> =rown extremely gravelly sand. The main limitations of 1 ,- verett soil for septic tank <br /> Permeability of the Everett soil is d.Available water absorption fields are st--,•ness of slope and seepage. If <br /> capacity is low.Effective rooting a-•th is 60 inches or the density of housi ,• moderate to high,community <br /> more.Runoff is rapid,and the - - a of water erosion is sewage systems - - needed to prevent contamination of <br /> moderata water supplies = = result of seepage from onsite <br /> This unit is used main, as woodland and for wildlife sewage di a a :1 systems. Road cuts tend to slough <br /> habitat.it is also -a or urban development readily. <br /> Douglas-fir is 4 = ain woodland species on the To pro , the soils in this unit from erosion during <br /> Alderwood soil • ; the basis of a 100-year site curve, co -- ; '.n,disturbed areas need to be seeded and <br /> the mean s' index is 142.On the basis of a 50-year run should be controlled. <br /> site curve ; .- mean site index is 108.The annual ' map unit is in capability subclass Vile. <br /> incrente at culmination(CMAI)for MHO- - at age 65 <br /> is 146 •_ feet per acre. 5—Alderwood-Urban land complex,2 to 8 percent <br /> Dowries-fir is the main woodland =-cies on the slopes.This map unit is on till plains.Areas are irregular <br /> Everett soil.On the basis of a 1 t.a __ site curve,the in shape and are 100 to 1,000 acres in size.The native <br /> mean site index is 141.On 4 : oasis of a 50-year site vegetation is mainly conifers.Elevation is 50 to 550 feet. <br /> curve,the mean site in. -- 111.The mean annual The average annual precipitation is about 40 inches,the <br /> increment at culrninatic$ DMA)for Douglas-fir at age 65 average annual air temperature is about 50 degrees F, <br /> is 146 cubic feet per re. and the average frost-free season is 170 to 190 days. <br /> Among the tr of limited extent on this unit are This unit is about 60 percent Alderwood gravelly sandy <br /> western hemloc western redcedar,and red alder_ loam and about 25 percent Urban land.The components <br /> Among the .a. mon forest understory plants are salal, of this unit are so intricately intermingled that it was not <br /> evergreen s , kleberry,brackenfern,red huckleberry, practical to map them separately at the scale used. <br /> common o se,.and Oregon-grape. Included in this unit are small areas of McKenna and <br /> The n- ;limitation for the harvesting of timber is Norma soils and Terric Medisaprists in depressional <br /> stee a . of slope.Slope restricts the use of wheeled areas and drainageways on plains.Also included are <br /> and , acIced equipment in skidding opered.-s;cable small areas of soils that are very shallow over a <br /> yarding systems generally are safer - ,• =sturb the soils hardpan;small areas of Everett, Indianola,and Ragnar <br /> Less. Harvesting systems that lift a.- entirely off the soils on terraces and outwash plains; and soils that have <br /> ground reduce the disturbance a. $ protective layer of a stony and bouldery surface layer Included areas make <br /> duff. up about 15 percent of the total acreage. <br /> Logging roads require ' le surfacing for year-round The Alderwood soil is moderately deep over a hardpan <br /> use. Rock for road co uction is riot readily available and is moderately well drained. It formed in glacial till. <br /> on this unit..Establi ' g plant cover on steep road cut Typically,the surface layer is very dark grayish brown <br /> and fill slopes red -.- erosion.Steep yarding paths,skid gravelly sandy loam about 7 inches thick.The upper part <br /> trails,and timbre.4 are subject to rifling and gullying of the subsoil is dark yellowish brown and dark brown <br /> unless adequ-1 =water bars are provided or they are very gravel <br /> protected • aril cover. gravelly sandy loam about 23 inches thick.The <br /> lower part is olive brown very gravelly sandy loam about <br /> Seed' ®, olity is the main limitation for the 5 inches thick. A weakly cemented hardpan-is at a depth <br /> product, of timber. Reforestation can be accomplished of about 35 inches. Depth to the hardpan ranges from <br /> by planting Douglas-fir seedlings. if seed trees are 20 to 40 inches. <br /> present,natural reforestation of cutiver areas by red . Permeability of the Alderwood soil is moderately rapid <br /> alder occurs periodically.The high temperature and low above the hardpan and very slow through it. Available <br /> moisture content of the Everett soil during the growing water capacity is low. Effective rooting depth is 20 to 40 <br /> season cause high mortality of seedlings,especially inches. Runoff is slow,and the hazard of water erosion <br />