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Henry, D. W., Zakikhani, M., Theel, H. J., Lorentz, W. P., Harrelson, D. W., & Khan, M. S. (2016). Development of Soil Screening Levels and Site-Specific Dilution Attenuation Factors for the Fort Wingate Depot Activity. The US Army Engineer Research and Development Center (ERDC), ERDC TR-16-DRAFT.

has been cited by the following article:

• TITLE: Improved Approaches to Calculating Dilution and Attenuation Factor in Contaminant Hydrogeology

  AUTHORS: Xiangquan Li, Chunchao Zhang, Wanfang Zhou

  KEYWORDS: Contaminant Hydrogeology, Soil Screening Level, Solid Waste Management Unit

  JOURNAL NAME: Journal of Geoscience and Environment Protection, Vol.12 No.8, August 8, 2024

  ABSTRACT: Dilution and attenuation factor (DAF) has a major influence on soil-to-groundwater screening level calculation for protection of contaminant migration from soil into groundwater at solid waste management units (SWMUs). Risk assessment guidance prepared by U.S. Environmental Protection Agency for site investigation and remediation suggests a default DAF of 20. If the base assumptions included in the default DAF are recognized to be not representative of site conditions at a SWMU, calculation of site-specific DAF is recommended when sufficient data are collected to justify using a different DAF value for development of soil screening levels. Commonly used methods of calculating DAF include analytical and numerical simulations that often require too many parameters to be obtained in practice. This paper proposes a probability method to develop site-specific DAF. The approach uses data that are readily available through field reconnaissance and site-specific investigation. A case study is presented in which the probability method was applied to an actual SWMU, and the calculated DAF is compared with that calculated from a dilution method. The probability-based DAF is 67 at 90% probability percentile, which is comparable to the dilution-based DAF of 76. Based on the calculated site-specific DAFs, SSLs could be developed for the contaminants of potential concern and used for evaluation of migration pathways from a contamination source through soil to groundwater.