Remediation Technologies
National Grid uses a combination of common and innovative remediation technologies - ranging from excavation and bioremediation to chemical oxidation and ozone treatment - to clean up former MGP sites.
Oxygen injection is a form of bioremediation, which means it allows natural processes to clean up harmful chemicals in the environment. Microscopic "bugs," or microbes, live in soil and groundwater and eat certain harmful chemicals. When microbes completely digest these chemicals, they change them into water and harmless gases such as carbon dioxide. Adding oxygen to the soil helps create optimal conditions for bioremediation to occur.
Oxygen injection involves the injection of a 90 to 95 percent pure oxygen gas into groundwater to increase the concentration of dissolved oxygen, which is used by microorganisms that live in the soil to break down organic chemicals.
Ozone injection destroys organic chemicals through the process of chemical oxidation, which breaks down the targeted organic chemicals into carbon dioxide and water.
Ozone is generated from fresh air within the water treatment building now located at the corner of Clinton Avenue and Union Boulevard on the main site and delivered directly to the injection points. Ozone is highly soluble in water and moderate gas saturation can be achieved rapidly with simple injection.
Ozone is injected continuously into the groundwater behind a barrier wall installed in OU-1. The barrier wall was designed to contain and direct contaminants through the ozone treatment area.
