Parameter | site conditions | Values/conditions favourable for natural attenuation | Ranking (natural attenuation) |
Soil Permeability | Sands; K = 10−2 - 10−4 cm/sec | Moderate to high (i.e. sands, gravels,) K > 10−4 cm/sec | Favourable |
Groundwater gradient | 0.4% | Low to moderate | Favourable |
Depth to groundwater (thickness of vadose zone) | >8 m | Moderate to deep | Favourable |
Recharge | Mean annual rainfall = 2500 m; recharge rate = 0.83 m/yr | High | Favourable |
Moisture content | 12% - 35% | Moderate (avoid excessively wet or dry soil) | Favourable |
Dissolved oxygen (DO) | 4.8 - 5.8 mg/l | Minimum is 1 - 2 mg/l | Favourable |
Soil/water PH | 6.97 - 7.13 | 6 - 8 | Favourable |
Total Heterotrophic (TH) | 1 × 104 - 8.3 × 105 | - | Favourable |
Hydrocarbon Degraders (HD) | 3 × 104 - 1 × 193 | >1 × 105 | Favourable |
Ratio of TH/HD | 20% - 60% | HD is significant percentage of TH | Slightly Favourable |