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Snohomish County Area, Washington <br />5—Alderwood-Urban land complex, 2 to 8 percent slopes <br />Map Unit Setting <br />• National map unit symbol: 2hz9 <br />• Elevation: 50 to 800 feet <br />• Mean annual precipitation: 25 to 60 inches <br />• Mean annual air temperature: 48 to 52 degrees F <br />• Frost -free period: 180 to 220 days <br />• Farmland classification: Not prime farmland <br />Map Unit Composition <br />• Alderwood and similar soils: 60 percent <br />• Urban land: 25 percent <br />• Minor components: 15 percent <br />• Estimates are based on observations, descriptions, and transects of the <br />mapunit. <br />Description of Alderwood <br />Setting <br />• Landform: Till plains <br />• Parent material: Basal till <br />Typical profile <br />• H1 - 0 to 7 inches: gravelly ashy sandy loam <br />• H2 - 7 to 35 inches: very gravelly ashy sandy loam <br />• H3 - 35 to 60 inches: gravelly sandy loam <br />Properties and qualities <br />• Slope: 2 to 8 percent <br />• Depth to restrictive feature: 20 to 40 inches to densic material <br />• Natural drainage class: Moderately well drained <br />Insight Engineering Co. - Stormwater Site Plan 05/31/2022 <br />-10- <br />