Eh Eh helps to define, with pH, the state of oxidation-reduction equilibria in aqueous wastestreams. BOD, COD, and TOC BOD, COD, and TOC measurements in contaminated water, as in soils, provide indications of the biodegradable, chemically oxidizable, or combustible fractions of the organic contamination, respectively. Oil and grease may be present in a separate phase in groundwater. In addition to chemical parameters, geologic and hydrologic information is usually needed to plan and monitor a groundwater remediation. The average rate of groundwater flow can be estimated from the hydraulic conductivity, hydraulic gradient, and effective porosity.
Hydraulic gradient is calculated from groundwater elevations measured in monitor wells.
Effective porosity is usually assumed based on ranges of values cited in scientific literature or estimated from pumping tests. Hydraulic conductivity is usually estimated from slug tests or pumping tests. If an active groundwater extraction system is being planned, safe aquifer yields and boundary conditions must be established. These parameters require that pumping tests be conducted. Because many variables affect emission rates, this approach is limited by the representativeness of the model and by the input used.