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TECHNOLOGY EVALUATION REPORT, HYDROTECHNICS IN SITU FLOW SENSOR
Citation:
Tetra Tech EM Inc., AND M. A. SIMON. TECHNOLOGY EVALUATION REPORT, HYDROTECHNICS IN SITU FLOW SENSOR. U.S. Environmental Protection Agency, Washington, DC, EPA/540/R-02/500, 2001.
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Description:
The U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation (SITE) Program evaluated performance of HydroTechnics, Inc. flow sensors in measuring the three-dimensional flow pattern created by operation of the Wasatch Environmental, Inc. (WEI) groundwater circulation well (GCW). The GCW is a dual screened, in-well stripping system designed to remove volatile organic compounds (VOC) from groundwater. Operation of the GCW creates a groundwater flow pattern that forms a three-dimensional regime known as a "circulation cell". EPA's evaluation of the GCW circulation cell involved use of in situ groundwater velocity flow sensors that were developed at Sandia National Laboratories and manufactured by HydroTechnics, Inc.
This Technology Evaluation Report (TER) documents and summarizes the findings of EPA's evaluation of HydroTechnics' flow sensors. The flow sensors are in situ instruments that use a thermal perturbation technique to directly measure the velocity of groundwater flow in unconsolidated, saturated, porous media. The manufacturer claims that the flow meter can measure horizontal and vertical flow rates and direction in the range is 0.01 to 2.0 feet per day (ft/day) (0.3 to 60.96 centimeter per second [cm/s]).
The GCW is a patented system manufactured by WEI and was demonstrated at Cape Canaveral Air Station (CCAS) by the US Air Force Center for Environmental Excellence (AFCEE). AFCEE conducted a comprehensive evaluation of the GCW, including contaminant mass removal rates, groundwater dye tracer studies, and numerical modeling. Demonstration data collected by AFCEE are documented separately in "Groundwater Circulation Well Technology Evaluation at Facility 1381, Cape Canaveral Air Station, Florida Technology Summary Report" (Parsons 2001).
The primary conclusions of EPA's evaluation of the HydroTechnics flow sensors include:
During GCW operation, the groundwater velocities measured by all seven sensors increased by more than 0.1 ft/day, indicating that (1) the sensors were within the circulation cell established by the GCW, and (2) the horizontal extent of groundwater circulation was greater than 15 feet. Flow direction data further support the establishment of a circulation cell and that all the flow sensors are within the horizontal extent of groundwater circulation cell.
The demonstration data suggest that the flow sensors are responsive to changes in groundwater flow conditions and can be used to help define and evaluate the three-dimensional flow patterns.