Soil series profile
Helemano soil series
Helemano is a well drained soil with a silty clay surface, mapped on 25,247 acres in 1 county in HI. Hydrologic group A.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- A 100% of mapped acres
- Typical topsoil pH
- 6.5 slightly acidic · range 6.5–6.5
- Mapped area
- 25k acres in 1 county, 1 state
Typical Helemano profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–10 in (H1) | Silty clay | 6.5 | 50% | 5% | 3.5% |
| 10–41 in (H2) | Paragravelly silty clay | 6.5 | 50% | 5% | 0.65% |
| 41–60 in (H3) | Very paragravelly silty clay | 6.5 | 50% | 5% | 0.2% |
What this means
What Helemano soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Helemano soils is slightly acidic: pH 6.5, the range most vegetables, flowers and lawn grasses prefer.
Clayey topsoil covers 100% of mapped Helemano acres. Clay holds water and nutrients but drains slowly and compacts if worked wet: add compost, avoid tilling soggy soil and consider raised beds. The most common surface texture is silty clay (100% of mapped Helemano acres).
100% of mapped Helemano acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
100% of mapped acres is in hydrologic group A, where water soaks in fast. Lawns there dry out quickly; deeper, less frequent watering and organic matter help.
For a septic system
For conventional septic absorption fields, NRCS rates 100% of the acres in mapped Helemano soils very limited, 0% somewhat limited and 0% not limited.
Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Helemano soil is found
Mapped acres
Helemano is mapped in Hawaii.
| County | Acres | Share of county land |
|---|---|---|
| Honolulu County, HI | 25,247 | 6.6% |
Septic absorption fields
NRCS rating, share of Helemano acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 100.0% |
Drainage, water table and flooding
Share of Helemano acres
- Depth to seasonal high water table
- None reported within about 6.5 feet (median where reported).
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 60–60% (median 60%).
- Topsoil organic matter
- Median 3.5%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 100.0% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 100.0% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 0.0% |
| D: very slow infiltration (clayey, shallow or wet) | 0.0% |
| A/D: D as is, A if drained | 0.0% |
| B/D: D as is, B if drained | 0.0% |
| C/D: D as is, C if drained | 0.0% |
Sources & data dates
- Source
- USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
- Data date
- SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
- Scope
- All map unit components named Helemano (component kind "Series") in SSURGO: 25,247 acres.
- Method
- Shares are by mapped acres of Helemano components. The profile comes from the single largest Helemano component. Full methodology.