Arapaho-Roosevelt National Forest Area, Colorado, Parts of Boulder, Clear Creek, Gilpin, Grand, Park and Larimer Counties
The dominant drainage class is Somewhat excessively drained and the dominant hydrologic group is C (slow infiltration, moderate 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 Arapaho-Roosevelt National Forest Area, Colorado, Parts of Boulder, Clear Creek, Gilpin, Grand, Park and Larimer Counties.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Bullwark-Catamount families-Rock outcrop complex, 40 to 150 percent slopes | 69K | Somewhat excessively drained | B | Very limited | Very limited |
| Leighcan family, till substratum, 5 to 40 percent slopes | 63K | Somewhat excessively drained | C | Very limited | Very limited |
| Frisco-Catamount, moist families complex, 5 to 40 percent slopes | 54K | Well drained | D | Somewhat limited | Very limited |
| Leighcan-Catamount, moist families complex, 5 to 40 percent slopes | 51K | Somewhat excessively drained | C | Very limited | Very limited |
| Cypher-Wetmore-Ratake families complex, 5 to 40 percent slopes | 51K | Somewhat excessively drained | D | Very limited | Very limited |
| Cypher-Ratake families complex, 5 to 40 percent slopes | 50K | Somewhat excessively drained | D | Very limited | Very limited |
| Bullwark-Catamount families-Rubble land complex, 10 to 40 percent slopes | 47K | Somewhat excessively drained | B | Very limited | Very limited |
| Leighcan family, 40 to 75 percent slopes | 47K | Somewhat excessively drained | C | Very limited | Very limited |
| Leighcan family, 5 to 40 percent slopes | 45K | Somewhat excessively drained | C | Very limited | Very limited |
| Leighcan family, till substratum-Cryaquolls complex, 5 to 40 percent slopes | 44K | Somewhat excessively drained | C | Very limited | Very limited |
| Frisco, sandstone substratum-Howlett, moist-Scout, moist families complex, 5 to 40 percent slopes | 39K | Well drained | B | Somewhat limited | Very limited |
| Cirque land, 40 to 150 percent slopes | 37K | Very limited | Very limited | ||
| Leighcan family-Rock outcrop complex, 40 to 150 percent slopes, south aspects | 36K | Somewhat excessively drained | C | Very limited | Very limited |
| Leighcan-Catamount, moist families-Rock outcrop complex, 40 to 150 percent slopes | 33K | Somewhat excessively drained | C | Very limited | Very limited |
| Ratake-Cathedral families-Rock outcrop complex, 40 to 150 percent slopes | 32K | Somewhat excessively drained | D | Very limited | Very limited |
| Typic Haplustolls-Cathedral family-Rock outcrop complex, 40 to 150 percent slopes | 32K | Somewhat excessively drained | B | Very limited | Very limited |
| Leighcan family-Rock outcrop complex, 40 to 150 percent slopes | 30K | Somewhat excessively drained | C | Very limited | Very limited |
| Cryaquolls-Gateview family complex, 0 to 15 percent slopes | 29K | Poorly drained | B/D | Very limited | Very limited |
| Matcher family-Rock outcrop-Lithic Cryorthents complex, 40 to 150 percent slopes | 28K | Excessively drained | D | Very limited | Very limited |
| Catamount, moist-Leighcan families-Rock outcrop complex, 5 to 40 percent slopes | 27K | Excessively drained | D | Very limited | Very limited |
What This Means
Building & Foundations
About 88% 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, sandy or gravelly soils with low bearing capacity. A geotechnical assessment is recommended before building.
Septic Systems
About 100% of soils are rated "very limited" for septic absorption fields. The well-drained soils may actually drain too fast for standard leach fields, allowing effluent to reach groundwater. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Soils tend to drain very quickly, meaning nutrients and water don't stick around long. Raised beds with amended soil, drip irrigation, and heavy mulching will give the best results. Compost is your best friend here — it improves water retention dramatically.