Protect Drinking Waterwith Continuous, Unattended Monitoring

Importance of the Topic

Continuous monitoring of volatile organic compounds (VOCs) in drinking water sources is critical to protect public health and ensure timely response to chemical spills. High-profile events such as the 2014 Elk River incident demonstrate the vulnerability of municipal water supplies to industrial contaminants. Routine surveillance helps detect smaller, more frequent spills before they impact water treatment facilities.

Objectives and Study Overview

This paper describes the deployment of an automated VOC monitoring network along the Ohio River by the Ohio River Valley Water Sanitation Commission (ORSANCO). The primary goal is to provide unattended, near real-time analysis of 30 priority VOCs and generate alarms when concentrations exceed safety thresholds, enabling rapid emergency response.

Methodology and Instrumentation

The monitoring system integrates continuous purge and trap sample preparation with gas chromatography and ionization detection. Key components include:

• A SituProbe™ module for continuous extraction of VOCs from flowing water
• A Tri-Bed carbon concentrator for analyte preconcentration
• A DB-624 GC column (30 m × 0.32 mm ID, 1.8 µm film)
• An argon-based Micro Argon Ionization Detector (MAID) sensitive to compounds with ionization potential ≤ 11.7 eV
• An onboard toluene permeation tube for daily check standards
• A five-point linear calibration scheme spanning 1 to 10 ppb

Analyses are run every two hours without manual sample handling. The system is controlled via I/O or Modbus and can interface with SCADA or centralized servers for data acquisition and alerts.

Main Results and Discussion

The continuous monitoring system achieved detection limits of 1 ppb or lower for all target VOCs. Calibration remained stable over 4–6 months, reducing maintenance demands. Onboard check standards and daily continuing calibration verifications maintained data quality. Automated alarms were generated when VOC levels exceeded a 2 ppb threshold, ensuring timely notification of ORSANCO personnel.

Benefits and Practical Applications

• Unattended operation minimizes manual sampling labor and potential sample degradation
• Low consumable requirements support long-term field deployment
• Real-time data access and alarm notifications enhance incident management
• Compact, wall-mounted design integrates easily into existing water infrastructure

Future Trends and Applications

Potential advancements include:

• Integration with mass spectrometric detectors for improved compound identification
• Expansion to additional organic and emerging contaminants
• Cloud-based analytics and machine learning for predictive water quality management
• Deployment of networked sensor arrays for large-scale watershed monitoring

Conclusion

The implementation of the INFICON CMS5000 continuous monitoring system offers a robust solution for safeguarding drinking water sources. Its high sensitivity, stable calibration, low maintenance requirements and data connectivity enable proactive detection of chemical spills and improved protection of public health.

References

1. Centers for Disease Control and Prevention. 2014 West Virginia Chemical Release. 2014.
2. Luncan T. NRC Spill Report Summary. 2014.
3. Ohio River Valley Water Sanitation Commission. About-Us. 2015.
4. Schulte J. ORSANCO ODS/Emergency Response Program. EPA Archive Documents. 2015.
5. Ohio River Valley Water Sanitation Commission. River Facts/Conditions. 2015.