Snoqualmie Pass Area, Washington (Parts of King and Pierce Counties)
The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Snoqualmie Pass Area, Washington (Parts of King and Pierce Counties).
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Playco loamy sand, 30 to 65 percent slopes | 46K | Well drained | B | Very limited | Very limited |
| Nimue loamy sand, 30 to 65 percent slopes | 40K | Well drained | B | Very limited | Very limited |
| Playco very gravelly loamy sand, tuff substratum, 30 to 65 percent slopes | 40K | Well drained | B | Very limited | Very limited |
| Tokul gravelly medial loam, 8 to 15 percent slopes | 34K | Moderately well drained | B | Very limited | Very limited |
| Nimue loamy sand, tuff substratum, 30 to 65 percent slopes | 32K | Well drained | B | Very limited | Very limited |
| Pitcher sandy loam, 30 to 65 percent slopes | 28K | Well drained | B | Very limited | Very limited |
| Pitcher sandy loam, tuff substratum, 30 to 65 percent slopes | 28K | Well drained | B | Very limited | Very limited |
| Kaleetan sandy loam, 30 to 65 percent slopes | 24K | Well drained | B | Very limited | Very limited |
| Barneston gravelly ashy coarse sandy loam, 0 to 8 percent slopes | 23K | Somewhat excessively drained | A | Not limited | Very limited |
| Reggad very cobbly muck, 30 to 90 percent slopes | 21K | Excessively drained | A | Very limited | Very limited |
| Barneston gravelly ashy coarse sandy loam, 8 to 15 percent slopes | 20K | Somewhat excessively drained | A | Somewhat limited | Very limited |
| Haywire sandy loam, 30 to 65 percent slopes | 16K | Well drained | C | Very limited | Very limited |
| Tokul gravelly medial loam, 15 to 30 percent slopes | 16K | Moderately well drained | B | Very limited | Very limited |
| Nagrom sandy loam, 30 to 65 percent slopes | 16K | Well drained | C | Very limited | Very limited |
| Rock outcrop-Rubble land-Serene complex, 45 to 90 percent slopes | 15K | Very limited | Very limited | ||
| Elwell silt loam, 6 to 30 percent slopes | 15K | Moderately well drained | C | Very limited | Very limited |
| Water | 15K | Not rated | Not rated | ||
| Altapeak gravelly sandy loam, 30 to 65 percent slopes | 15K | Well drained | A | Very limited | Very limited |
| Zynbar loam, 6 to 30 percent slopes | 15K | Well drained | B | Very limited | Very limited |
| Index loamy sand, 30 to 65 percent slopes | 14K | Well drained | A | Very limited | Very limited |
What This Means
Building & Foundations
About 87% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes. A geotechnical assessment is recommended before building.
Septic Systems
About 96% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.