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Snohomish County Area,Washington <br /> 4---Alderwood-Everett gravelly sandy loams, 25 to 70 percent slopes <br /> Map Unit Setting <br /> National map unit symbol: 2hyy <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 /> • Everett and similar soils: 25 percent <br /> Minor components: 15 percent <br /> • Estimates are based on observations, descriptions, and transects of the mapunit. <br /> Description of Alderwood <br /> Setting <br /> • Landform: Till plains <br /> Parent material: Basal till <br /> Typical profile <br /> • H 1 - 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: 25 to 70 percent <br /> Depth to restrictive feature: 20 to 40 inches to densic material <br /> • Natural drainage class: Moderately well drained <br /> • Capacity of the most limiting layer to transmit water(Ksat): Very low to <br /> moderately low (0.00 to 0.06 in/hr) <br /> Depth to water table: About 18 to 36 inches <br /> • Frequency of flooding: None <br /> • Frequency of ponding: None <br /> • Available water storage in profile: Low(about 3.0 inches) <br /> Interpretive groups <br /> • Land capability classification (irrigated): None specified <br /> • Land capability classification (nonirrigated): 7e <br /> • Hydrologic Soil Group: B <br /> Hydric soil rating: No <br /> Insight Engineering Co. -Stormwater Site Plan 07/24/19 <br /> -8- <br />