Aniwa region's typical geology: surficial sand and gravel overlying weathered granite, then hard granite to depth.
Showing contractors within 60 miles of Aniwa. 36 results found.
A geological estimate for the Aniwa area.
Typical Well Depth
Static Water Level
Recommended Method
Based on a synthesis of well logs in the Aniwa area, the most representative geological profile is a shallow, unconsolidated sand and gravel aquifer extending generally 10-60 ft bgs (below ground surface), underlain by a transition zone of decomposed/weathered granite (often clayey) to approximately 20–40 ft, grading into hard crystalline granite bedrock that continues to total drilled depths of 150–200+ ft. The most reliable groundwater supplies come from the sand/gravel or fractured/weathered bedrock interface. Wells in this area commonly use rotary mud drilling, are cased through the unconsolidated overburden, and grouted typically to 40 ft with cement. Residential wells targeting 5-15+ GPM are most often completed in the upper 100–200 ft.
| Depth (Feet) | Formation Type | Description | Characteristics |
|---|---|---|---|
| 0 – 10 ft | Clay or Silty Sand | Surface clay, silty sand, or sandy clay occasionally mixed with stones; noncaving; acts as a confining layer. | Color: Brown/grey Hardness: Soft to firm |
| 10 – 50 ft | Sand & Gravel | Coarse sand and gravel; major water-bearing zone; highly permeable and caving. | Color: Tan/yellow Hardness: Unconsolidated |
| 50 – 80 ft | Decomposed/Weathered Granite (occasionally clayey) | Transition zone of decomposed, weathered, or clayey granite; moderately firm, may contain some fine sand or gravel lenses. | Color: Reddish to grey Hardness: Firm to hard |
| 80 – 200 ft | Hard Granite/Crystalline Bedrock | Red or green/black hard crystalline granite bedrock, fractured locally; groundwater encountered in upper fractured intervals; beyond 150–200' yields typically drop. | Color: Red/green/black Hardness: Hard rock |