Guidance for the Determination of the Dilution-Attenuation Factor for the Impact to Ground Water Pathway

The guidance document explains the use of the dilution-attenuation factor in determining impact to ground water. When infiltrating soil water reaches the water table, it is mixed with ground water and contaminants are diluted. The resulting contaminant concentration in the groundwater is therefore lower than that in the infiltrating water. A dilution-attenuation factor (DAF) is used to account for this process. This factor is described in the USEPA Soil Screening Level (SSL) document (USEPA 1996). The factor is used in the various options for calculating impact to groundwater soil cleanup criteria, including calculation of the Leachate Criterion (LC).NJDEP Site Remediation Program: Remediation Standards Guidance DocumentsSee NJEDL Record ID 5265 for the calculation spreadsheetPurpose: To provide guidance to remediating parties on the use of the dilution-attenuation facto