Islands of Aguijan, Rota, Saipan and Tinian, Commonwealth of the Northern Mariana Islands
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 Islands of Aguijan, Rota, Saipan and Tinian, Commonwealth of the Northern Mariana Islands.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Dandan-Chinen complex, 0 to 5 percent slopes | 7K | Well drained | C | Very limited | Very limited |
| Chinen clay loam, 5 to 15 percent slopes | 6K | Well drained | D | Very limited | Very limited |
| Luta cobbly clay loam, 0 to 5 percent slopes | 5K | Well drained | D | Very limited | Very limited |
| Chinen clay loam, 0 to 5 percent slopes | 5K | Well drained | D | Very limited | Very limited |
| Chinen-Urban land complex, 0 to 5 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Luta cobbly clay loam, 5 to 15 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Takpochao-Rock outcrop complex, 30 to 60 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Chinen clay loam, 15 to 30 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Takpochao-Rock outcrop complex, 3 to 15 percent slopes | 3K | Well drained | D | Very limited | Very limited |
| Luta-Rock outcrop complex, 5 to 15 percent slopes | 3K | Well drained | D | Very limited | Very limited |
| Takpochao-Rock outcrop complex, 15 to 30 percent slopes | 3K | Well drained | D | Very limited | Very limited |
| Rock outcrop-Takpochao complex, 60 to 99 percent slopes | 3K | Well drained | D | Very limited | Very limited |
| Chinen very gravelly sandy loam, 0 to 5 percent slopes | 2K | Well drained | C | Very limited | Very limited |
| Dandan-Chinen complex, 5 to 15 percent slopes | 2K | Well drained | C | Very limited | Very limited |
| Luta-Rock outcrop complex, 15 to 30 percent slopes | 2K | Well drained | D | Very limited | Very limited |
| Saipan clay, 0 to 5 percent slopes | 1K | Well drained | B | Somewhat limited | Somewhat limited |
| Kagman clay, 0 to 5 percent slopes | 1K | Well drained | C | Somewhat limited | Very limited |
| Shioya loamy sand, 0 to 3 percent slopes | 1K | Somewhat excessively drained | A | Very limited | Very limited |
| Luta-Rock outcrop complex, 0 to 5 percent slopes | 1K | Well drained | D | Very limited | Very limited |
| Chinen-Rock outcrop complex, 3 to 15 percent slopes | 1K | Well drained | D | Very limited | Very limited |
What This Means
Building & Foundations
About 95% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 97% 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.