Benefits and Limitations of Using Down Well, Real-time, Telemetric Water Quality Meters to Monitor Water Quality

Background

While recent developments in real-time, telemetric water quality meters provides benefits over older equipment and grab sampling using manual methods, an understanding of both the benefits and limitations of new technology is required for successful application.

With respect to benefits, current technology allows operation of real-time sensors in the field for several months without calibration or maintenance, reducing labor requirements at remote sensing sites. A multiparameter probe allows collection of a multitude of important parameters using a single integrated system, and can incorporate state-of-the art sensing methods for each parameter in a unit small enough to insert in a 2-inch groundwater monitoring well. The addition of telemetry and web-based data management allows real-time review and evaluation of field data from multiple locations, near or far.

Review of technical literature, discussions with technical experts, and personal experience operating equipment under various field conditions, also allowed definition and verification of equipment limitations related to installation, accuracy, telemetry, and data management.

Objectives

This presentation will compare the benefits and limitations of example equipment (In-Situ Inc. Aqua TROLL 600 and Tube 300R) at four sites in four different states and their water quality conditions.

Benefits

1. Provides a continuous, real-time record of groundwater conditions using accurate water quality parameters.
2. Detect short-term events (i.e. minutes to several days) that can be missed during monthly or quarterly manual sampling events.
3. Monitor water level, temperature, total dissolved solids, oxygen-reduction potential, dissolved oxygen, turbidity, pH, nitrate, ammonia, and chloride, downhole.

Limitations

1. Location and/or configuration of the monitoring point may limit the Tube 300R telemetry system’s ability to transmit real-time data.
2. The total set of parameters is limited.
3. Because the equipment is connected and suspended by cables, site-specific cable lengths and suspension devices are needed.