Tactic TR-4: Irrigation
Irrigation is the application of water to improve growing conditions for plants and the soil microbes to metabolize hydrocarbons. Water is applied by flooding (Tactic CR-7), or by spraying with hoses (Fig. 81) and sprinklers (Fig. 82). Water sprayed on a site will have a relatively high concentration of dissolved oxygen, which will enhance the ability of soil microbes to degrade hydrocarbons. Water can be pumped from a lake or pond near the spill site and sprayed onto the surrounding area repeatedly as the water drains back into the waterbody. This method is commonly referred to as the pump-and-treat method.
Flooding for irrigation can be implemented in the same manner described for flooding to remove contaminants (Tactic CR-7). Irrigation by flooding may require land barriers (Tactic CR-5) to maintain desirable water levels and prevent the spread of contaminants into unaffected tundra. Flooding may be appropriate for rehabilitating wet and moist tundra dewatered during cleanup of contaminants.
To protect plants from exposure to extremely cold air, the site may be covered with snow (Fig. 83) or water, which then freezes. The snow and ice will provide moisture during the spring, a time when there is typically little rainfall.
Considerations and Limitations
- This tactic is most applicable during dry periods of the growing season.
- Verify that water is free of hydrocarbons and salts before using it to irrigate tundra.
- Rainfall events may require modification of the watering schedule.
Equipment, Materials, and Personnel
- Water truck (optional) (1 operator).
- Pumps (1 operator).
- Hoses (1 operator) – common sizes are 2- and 3-inch diameter.
- Sprinklers (1 operator).
- Clean water source – may be a nearby pond or creek.
- Power pack - for pumps.