Chatham Area, Alaska
The most common soil here is Tolstoi, on about 5% of the land: a very fine sandy loam, gritty and crumbly. Lithic Cryorthents and E20-maritime forest-loamy colluvial slopes, shallow come next.
About 7% of the land drains well, and 32% stays wet for long stretches; groundwater comes within two feet of the surface under 54% of it.
USDA rates 70% of the land very limited for a standard septic drain field, and 70% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 3% of the land floods occasionally or more, and bedrock lies within 40 inches under 60% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Chatham Area, Alaska, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Very poorly drained and the dominant hydrologic group is A/D (varies with drainage). The most common soil order is Spodosols — acidic forest soils with a distinctive leached layer, common under conifers. 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 Chatham Area, Alaska. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Water, Saline | 1.1M | Not rated | Not rated | ||
| Alexander Archipelago-Gulf of Alaska Coast-Maritime Upland and Subalpine-Rounded Mountains | 761K | Very poorly drained | A/D | Very limited | Very limited |
| Rock outcrop and Lithic Cryorthents | 601K | Very limited | Very limited | ||
| Southern Alaska Coastal Mountains-Maritime Alpine-Barren Mountains | 551K | Not rated | Not rated | ||
| Glaciers | 347K | Not rated | Not rated | ||
| Southern Alaska Coastal Mountains-Maritime Subalpine and Alpine-Mountains | 268K | Very limited | Very limited | ||
| Typic Humicryept and Lithic Cryorthent soils, 76 to 140 percent slopes | 260K | Moderately well drained | A | Very limited | Very limited |
| Tolstoi and Kaikli soils, alpine, 76 to 120 percent slopes | 173K | Moderately well drained | D | Very limited | Very limited |
| Southern Alaska Coastal Mountains-Maritime Upland-Mountains | 101K | Moderately well drained | B/D | Very limited | Very limited |
| Lithic Cryorthent-Entic Cryumbrept association, 76 to 140 percent slopes | 101K | Somewhat poorly drained | D | Very limited | Very limited |
| Alexander Archipelago-Gulf of Alaska Coast-Maritime Upland-Glaciated Hills and Plains | 100K | Very poorly drained | A/D | Very limited | Very limited |
| Alexander Archipelago-Gulf of Alaska Coast-Maritime Subalpine and Alpine-Rounded Mountains | 100K | Very limited | Very limited | ||
| Water | 90K | Not rated | Not rated | ||
| Entic Cryumbrepts-Tolstoi-Kupreanof association, 76 to 140 percent slopes | 86K | Moderately well drained | A | Very limited | Very limited |
| Lithic Cryosaprists, Alpine, and Rock outcrop soils, 0 to 35 percent slopes | 85K | Very poorly drained | D | Very limited | Very limited |
| Alexander Archipelago-Gulf of Alaska Coast-Maritime Upland and Subalpine-Rounded Mountains, Ash Infuenced | 83K | Moderately well drained | D | Very limited | Very limited |
| Tolstoi and Kaikli soils, subalpine, 36 to 55 percent slopes | 64K | Moderately well drained | D | Very limited | Very limited |
| Kina-Kasiana association, sloping lowlands, 6 to 35 percent slopes | 60K | Very poorly drained | D | Very limited | Very limited |
| Entic Cryumbrepts, McGilvery, and Rock outcrop soils, ravines, 76 to 140 percent slopes | 49K | Moderately well drained | A | Very limited | Very limited |
| Alexander Archipelago-Gulf of Alaska Coast-Maritime Upland and Lowland-Mountain Valley Bottoms | 46K | Moderately well drained | B/D | Very limited | Very limited |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 70% 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 70% of soils are rated "very limited" for septic absorption fields. Poorly drained soils can't absorb septic effluent effectively. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Many soils hold water for extended periods. Raised beds are highly recommended to improve drainage for vegetables. Well-adapted native plants and water-loving species will do best in natural conditions.