The objective of this project is to develop and test a method for in situ measurement of high resolution contaminant and water flux profiles that eliminates the high cost of analysis through the use of colorimetric responses. Measurement of flux is critical to design and evaluate remedial strategies that rely on targeted injection of stimulants that promote reactions, biological or abiotic, to reduce contamination. High resolution data can reveal plume core structure, which in turn can lead to reduced deployment of remedial agents and result in more effective remediation at lower costs. The challenge with the collection of high resolution data is in part the analytical costs of high numbers of samples. This project is aimed at lowering the cost of collecting high resolution data though the use of a passive flux meter (PFM) design that employs sorbents and reactants that respond to water flow and contaminant loading through color changes.

This project will develop a colorimetric-based cPFM for measuring contaminant fluxes and groundwater specific discharge. Researchers will adapt field-tested concepts from PFMs designed to measure the fluxes of hydrophobic organics. Laboratory studies will be conducted to screen candidate sorbents and dyes to modify the current PFM design and validate the changes under controlled laboratory conditions. Both Darcy flux and contaminant flux will be quantified using dyes or reactions that lead to color changes proportional to the flux of water or contaminant. A field evaluation of the new approach will be conducted in coordination with SERDP-funded projects focusing on remedial evaluations at chlorinated solvent contaminated sites. This phase will proceed only after successful development of a PFM design capable of quantifying contaminant and Darcy flux using colorimetric techniques.

Flux-based data can be used to target remedial actions where contaminant fluxes are greatest and to reduce the costs associated with aquifer restoration. Knowing in advance where contaminant fluxes are greatest permits one to optimize the physical configuration of injected amendments. This type of performance-based design will reduce the need for over-design, decrease the risks of inadequate system design, and create opportunities to improve cost-effective use of reactive media. The development of a reduced cost approach to collecting high resolution data will lead to increased use and subsequent cost savings. (Anticipated Project Completion - 2018)

Augustine S., J. Cho, H. Klammler, K. Hatfield, M.D. Annable. 2020. Sediment Bed Borehole Advection Method. Water, 12 (2020).

Chardi, K., K. Dombrowski, J. Cho, M. Newman, K. Hatfield, and M.D. Annable. A Colorimetric-Based Passive Flux Meter for Measuring Groundwater Flux. Manuscript under revision for publication in Water Research.

Haluska, A.A., M. Thiemann, P.J. Evans, J. Cho, M.D. Annable. 2018. Expanded Application of the Passive Flux Meter: In-Situ Measurements of 1,4-Dioxane, Sulfate, Cr(VI) and RDX. Water, 10 (10).

Klammler, H., K. Hatfield, M. A. Newman, J. Cho, M. D. Annable, B. L. Parker, J. A. Cherry, and I. Perminova. 2016. A New Device for Characterizing Fracture Networks and Measuring Groundwater and Contaminant Fluxes in Fractured Rock Aquifers. Water Resources, 52: 5400– 5420. doi:10.1002/2015WR018389.