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Measurement of LNAPL Flow Using Single‐Well Tracer Dilution Techniques
Author(s) -
Sale Tom,
Taylor Geoffrey Ryan,
Iltis Gabriel,
Lyverse Mark
Publication year - 2007
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.2007.00337.x
Subject(s) - tracer , dilution , volumetric flow rate , flow (mathematics) , indicator dilution , chemistry , soil science , geology , mechanics , thermodynamics , medicine , physics , radiology , cardiac output , nuclear physics , blood pressure
This paper describes the use of single‐well tracer dilution techniques to resolve the rate of light nonaqueous phase liquid (LNAPL) flow through wells and the adjacent geologic formation. Laboratory studies are presented in which a fluorescing tracer is added to LNAPL in wells. An in‐well mixer keeps the tracer well mixed in the LNAPL. Tracer concentrations in LNAPL are measured through time using a fiber optic cable and a spectrometer. Results indicate that the rate of tracer depletion is proportional to the rate of LNAPL flow through the well and the adjacent formation. Tracer dilution methods are demonstrated for vertically averaged LNAPL Darcy velocities of 0.00048 to 0.11 m/d and LNAPL thicknesses of 9 to 24 cm. Over the range of conditions studied, results agree closely with steady‐state LNAPL flow rates imposed by pumping. A key parameter for estimating LNAPL flow rates in the formation is the flow convergence factor α . Measured convergence factors for 0.030‐inch wire wrap, 0.030‐inch‐slotted polyvinyl chloride (PVC), and 0.010‐inch‐slotted PVC are 1.7, 0.91, and 0.79, respectively. In addition, methods for using tracer dilution data to determine formation transmissivity to LNAPL are presented. Results suggest that single‐well tracer dilution techniques are a viable approach for measuring in situ LNAPL flow and formation transmissivity to LNAPL.