SEBA Dipper-TEC Submersible Groundwater Level, Temperature & Conductivity Monitoring System

Overview

The SEBA Dipper-TEC is a fully self-contained, submersible multiparameter monitoring system engineered for long-term, high-stability measurement of groundwater level, temperature, and electrical conductivity in confined aquifers, monitoring wells, and surface water bodies. Based on piezoresistive ceramic pressure transduction with integrated barometric compensation, the Dipper-TEC eliminates atmospheric pressure drift—ensuring hydrostatic head measurements remain unaffected by diurnal or seasonal barometric fluctuations. Its compact 22 mm diameter and 270 mm length allow direct deployment into standard 2-inch (50.8 mm) boreholes without requiring well enlargement or auxiliary housings. The system operates autonomously using a sealed lithium primary battery, delivering over a decade of continuous operation at typical 60-minute logging intervals. Designed for unattended field use in remote or infrastructure-limited environments, the Dipper-TEC meets the operational rigor demanded by environmental consultants, regulatory agencies, and hydrogeological research programs under ISO 14001, ASTM D4044, and EU WFD (Water Framework Directive) monitoring protocols.

Key Features

• Barometrically compensated ceramic pressure sensor with ±0.05% full-scale accuracy and 0.3 mm resolution in the 0–10 m range
• Integrated temperature sensor (PT1000 or NTC) with ±0.1 °C accuracy across –5 to +50 °C, supporting thermal correction of conductivity and density-dependent level calculations
• Four-electrode conductivity cell offering four selectable ranges (0–200 µS/cm to 0–200 mS/cm) with ±0.5% full-scale accuracy and minimal polarization error
• 1 MB onboard flash memory storing up to 480,000 timestamped records (level, temperature, conductivity, battery voltage)
• Configurable logging interval from 1 minute to 45 days via ASCII command set over RS485
• IP68-rated stainless-steel housing with pressure-compensated cable assembly and desiccant chamber to prevent internal condensation and ensure signal integrity over multi-year deployments
• Low-power 16-bit microcontroller architecture optimized for extended battery life (>10 years at 60-min intervals)

Sample Compatibility & Compliance

The Dipper-TEC is validated for deployment in freshwater, brackish, and low-salinity groundwater systems (conductivity ≤200 mS/cm). Its ceramic sensor and 316L stainless-steel wetted parts resist corrosion in mildly aggressive geochemical environments, including those with elevated iron, manganese, or sulfide concentrations. The system complies with EN 14897 (groundwater monitoring equipment), supports GLP-aligned data integrity through time-stamped, non-volatile storage, and enables traceable calibration via factory-certified sensor documentation (NIST-traceable where applicable). While not FDA 21 CFR Part 11–certified as a standalone device, its ASCII output format and deterministic logging behavior facilitate integration into validated laboratory information management systems (LIMS) and environmental data management platforms compliant with EPA Method 1600-series reporting requirements.

Software & Data Management

Data retrieval is performed via the SEBA-HAD handheld reader—a ruggedized Windows Mobile 2003 device with IP67 ingress protection, touchscreen interface, and dual RS232/USB connectivity. The HAD reader executes real-time data download, configuration updates, and battery diagnostics using SEBA’s proprietary DipperConfig software. All raw data are stored in plain-text ASCII format, enabling direct import into MATLAB, Python (Pandas), R, or commercial hydrological modeling tools (e.g., MODFLOW, GMS). No proprietary binary formats or vendor-locked drivers are used. Field operators may perform zero-offset verification and thermal drift checks in situ using the HAD’s built-in diagnostic mode. For networked deployments, optional Bluetooth-enabled HAD units support wireless data offload to tablets or edge gateways running custom MQTT or HTTP(S) ingestion services.

Applications

• Long-term groundwater level trend analysis for aquifer sustainability assessment and drought monitoring
• Salinity intrusion tracking in coastal aquifers via synchronized level–conductivity–temperature profiling
• Wellhead protection zone (WHPZ) monitoring per US EPA guidance and state-level UIC program requirements
• Post-remediation monitoring of contaminated sites (e.g., DNAPL plume migration, redox zonation)
• Calibration and validation of distributed fiber-optic DTS/DAS systems in borehole arrays
• Surface water–groundwater interaction studies in riparian zones and floodplain aquifers

FAQ

Can the Dipper-TEC be deployed in artesian wells with pressures exceeding atmospheric?

Yes—the sensor’s pressure rating extends to 50 bar, accommodating artesian conditions up to ~500 m hydraulic head. Custom pressure ranges are available upon request.
Is firmware upgrade supported in the field?

Firmware updates require connection to the HAD reader and DipperConfig software; no over-the-air (OTA) capability is provided due to the system’s focus on long-term stability and auditability.
How is barometric compensation implemented?

A separate, co-located barometric reference sensor is not required—the Dipper-TEC’s pressure-compensated cable design passively equalizes ambient air pressure at the sensor diaphragm, eliminating the need for secondary atmospheric pressure logging.
What is the maximum allowable cable length for reliable RS485 communication?

Up to 1000 meters is supported using shielded twisted-pair cable meeting EIA/TIA-485-A specifications, with proper termination and grounding practices.
Does the conductivity measurement require periodic cleaning or recalibration?

The 4-electrode geometry minimizes fouling-related drift; however, annual visual inspection and cleaning with dilute citric acid are recommended for deployments in high-biofouling or high-sediment environments. Factory recalibration is advised every 2–3 years for regulatory-grade applications.