Placer County, California, Western Part
The dominant drainage class is Well drained and the dominant hydrologic group is D (very slow infiltration, high runoff). 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 Placer County, California, Western Part.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Cometa-Fiddyment complex, 1 to 5 percent slopes | 24K | Well drained | D | Not limited | Very limited |
| Andregg coarse sandy loam, 2 to 9 percent slopes | 19K | Well drained | B | Somewhat limited | Very limited |
| Maymen-Rock outcrop complex, 50 to 75 percent slopes | 16K | D | Very limited | Very limited | |
| San Joaquin-Cometa sandy loams, 1 to 5 percent slopes | 15K | Well drained | D | Very limited | Very limited |
| Auburn silt loam, 2 to 15 percent slopes | 12K | Well drained | C | Very limited | Very limited |
| Cometa-Ramona sandy loams, 1 to 5 percent slopes | 11K | Well drained | D | Not limited | Very limited |
| Redding and Corning gravelly loams, 2 to 9 percent slopes | 11K | Well drained | D | Somewhat limited | Very limited |
| Auburn-Rock outcrop complex, 2 to 30 percent slopes | 11K | Well drained | C | Very limited | Very limited |
| Mariposa-Rock outcrop complex, 50 to 70 percent slopes | 10K | Well drained | C | Very limited | Very limited |
| Mariposa-Rock outcrop complex, 5 to 50 percent slopes | 10K | Well drained | C | Very limited | Very limited |
| Auburn-Sobrante-Rock outcrop complex, 2 to 30 percent slopes | 10K | Well drained | C | Very limited | Very limited |
| San Joaquin sandy loam, 1 to 5 percent slopes | 10K | Well drained | D | Very limited | Very limited |
| Mariposa-Josephine complex, 5 to 30 percent slopes | 10K | Well drained | C | Very limited | Very limited |
| Fiddyment-Kaseberg loams, 2 to 9 percent slopes | 9K | Well drained | C | Very limited | Very limited |
| Mariposa-Josephine complex, 30 to 50 percent slopes | 9K | Well drained | C | Very limited | Very limited |
| Auburn-Sobrante silt loams, 15 to 30 percent slopes | 8K | Well drained | C | Very limited | Very limited |
| Kilaga loam | 8K | Well drained | C | Somewhat limited | Very limited |
| Xerofluvents, frequently flooded | 8K | Somewhat poorly drained | B | Very limited | Very limited |
| Rock outcrop | 8K | D | Very limited | Very limited | |
| Auburn-Sobrante-Rock outcrop complex, 30 to 50 percent slopes | 7K | Well drained | D | Very limited | Very limited |
What This Means
Building & Foundations
About 67% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 100% 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.