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Seepage Flux Calculation Workbooks
Citation:
Lien, B. AND R. Ford. Seepage Flux Calculation Workbooks. U.S. Environmental Protection Agency, Washington, DC, EPA/600/C-18/137, 2018.
Impact/Purpose:
The Seepage Flux Calculation Workbooks use sediment temperature to quantify the magnitude and direction of water flux across the groundwater-surface water transition zone.
Description:
Identifying the spatial distribution and magnitude of seepage flux across the groundwater‐surface water (GW‐SW) interface is critical for assessing potential impairments and restoration alternatives for water bodies adjacent to sites with groundwater contamination. Measurement of the vertical distribution and time‐varying characteristics of temperature in sediments provides an indirect way to map out spatial and temporal patterns of seepage flux into surface water. Two spreadsheet‐based calculation tools are introduced that implement four one‐dimensional analytical solutions to calculate the magnitude and direction of seepage flux based on measurement of steady‐state vertical temperature profiles or transient diel temperature signals at two depths within sediment. Performance of these calculation tools is demonstrated for a pond receiving contaminated groundwater discharge from an adjacent landfill. Transient versus steady‐state model performance is compared, and limitations of transient models are illustrated for a situation with unfavorable sediment characteristics and inadequate sensor spacing. The availability of a range of analytical solutions implemented within Microsoft Excel® is intended to encourage practitioners to explore use of this seepage flux characterization method and develop greater insight into best practices for model selection and use.
