General analytical treatment of the flow field relevant to the interpretation of passive fluxmeter measurements

Abstract

[1] Relevant flow dynamics for the interpretation of passive fluxmeter (PFM) measurements are investigated by determining the properties of the flow field inside the PFM and its relationship to the undisturbed ambient fluxes in the aquifer. The flow domain is treated in two dimensions and consists of a system of concentric annular filter zones of different radii and hydraulic conductivities. Flow inside the PFM is shown to be uniform regardless of well configuration. Analytical expressions quantifying flow convergence are derived for an increasing number of rings, validated against numerical modeling and used to perform a sensitivity analysis. One of the derived convergence relationships is embedded in an inverse model to estimate aquifer and well screen conductivities and ambient groundwater and methyl-tertiary-butyl-ether (MTBE) fluxes in the Borden Aquifer under controlled flow conditions. Results compare well to independent estimates when the method of quantifying convergence is consistent with field conditions.

Diagnostic Tools for Performance Evaluation of Innovative In-Situ Remediation Technologies at Chlorinated Solvent-Contaminated Sites

“…The convergence/divergence factor (α 3 ) for a well within a sandpack can be estimated using the following expression (Klammler et al, 2007a). …”

Field Demonstration and Validation of a New Device for Measuring Water and Solute Fluxes at CFB Borden

“…Strack and Haitjema, (1981) and Klammler et al, (2006a) show that is linearly proportional to : α given a PFM installed in a fully screened well without a filter pack.…”

“…Normally, the value of α is not known in advance because the local aquifer permeability is not known. Klammler et al (2006a) suggests a PFM design whereby the value of α is forced to assume a constant and predictable value; the design requires that sorbent and well screen possess hydraulic conductivities at least an order of magnitude greater than the hydraulic conductivity of the aquifer. In lieu of this approach, a short-term field test can be performed involving a sequence of two water flux measurements.…”

“…Primary consideration must be given to the desired sampling period (short-or long-term monitoring), the contaminant of interest, the nature of the sorbent to be used and the availability of non-toxic resident tracers with sufficiently large retardation factors. Assuming suitable sorbent and resident tracers exist, a flux meter can be designed using estimated permeabilities for the aquifer, the well screen and the sorbent (Klammler, et al 2006a). …”

Field Demonstration and Validation of a New Device for Measuring Water and Solute Fluxes at Naval Base Ventura County (NBVC), Port Hueneme, CA

“…where α' is a factor that can be calculated from the geometry of the well and the estimated permeabilities of the aquifer, the well screen, the well packing, and the sorbent (Hatfield et al, 2004;Annable et al, 2005;Klammler, et al, 2006).…”