Geo-Cleanse monitors pH, alkalinity, dissolved iron, hydrogen peroxide and chloride concentrations, PID headspace, and temperature taken from groundwater samples obtained daily from the injection wells and monitoring wells within the treatment area. These field parameters monitor the reaction progress and ensures that appropriate subsurface conditions exist for an efficient reaction. They also assist Geo-Cleanse in proportioning additional reagents into areas on-site where contamination still exists. These parameters indicate the following:
pH: Catalyzed hydrogen peroxide is generally most efficient under acidic pH conditions (pH<5) because oxidation of iron by other reactions is minimized, hydrous ferric iron oxides are less likely to precipitate (removing iron from solution), and bicarbonate is neutralized.
Alkalinity: Alkalinity is a measure of the amount of dissolved carbonate in groundwater. Carbonates are scavengers for the hydroxyl free radical that can lessen the efficiency and effectiveness of a Fenton's reagent injection.
Dissolved Iron: Ferrous iron is oxidized to ferric iron in the subsurface and precipitates as an iron oxide or iron hydroxide. This compound is used to catalyze hydrogen peroxide to form the hydroxyl free radical thus it is measured to ensure that appropriate conditions to form hydroxyl free radicals exist.
Hydrogen Peroxide: Injected into groundwater and soils at a maximum concentration of 25%, with resultant concentrations to groundwater of less than 1%. The hydrogen peroxide is typically consumed completely within 3 days. This parameter is only monitored at sites where Fentonís reagent is used.
Chloride: A by-product of the breakdown of chlorinated hydrocarbons using Fentonís reagent, this measurement is a useful field parameter, in conjunction with pre- and post- treatment analytical, to determine if contaminant destruction is occurring. This parameter is only measured at sites where chlorinated hydrocarbon contamination exists.
PID headspace: A portable, non-specific vapor/gas detector employing the principal of photo ionization to detect a variety of chemical compounds, both organic and inorganic, in air. GCI uses this measurement to proportion reagents to the areas on site where additional contamination is present.
Temperature: Measurements of groundwater temperature are taken during the injection to monitor the exothermic nature of the chemical oxidation reaction.
Geo-Cleanse also monitors offgas concentrations from the injectors and the monitoring wells within the treatment area during ISCO injection. These offgas parameters, coupled with the groundwater measurements are effective in determining the progress of an ISCO treatment program in the field.
Carbon dioxide: Oxidation of organic compounds yields carbon dioxide, which is liberated from the subsurface through adjacent injectors and monitoring wells. CO2 production is a sensitive measure of the efficiency and progress of the treatment.
Oxygen: Reaction of hydroxyl free radicals with hydrogen peroxide, other radicals, or other non-organic compounds produces oxygen. Oxygen is liberated from the subsurface through adjacent injectors and monitoring wells.