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