Real-Time Remote Monitoring of a Distribution System – A Case

Study in Washington D.C.

Srinivas Panguluri (Shaw Environmental, Inc.), Robert M. Clark (Consultant), and

Roy C. Haught (U.S. EPA - Water Supply and Water Resources Division)

Presented bySrinivas Panguluri, P.E.

Presentation Outline

o Overview of the Case Studyo System Selection and

Implementationo Lessons Learnedo Technology Trends Review o Q&A - Discussion

Overview of the Case Study

In 1996, following a number of Colifom violations EPA Region-3 directed DC Water and Sewer Authority (WASA) to implement several corrective actions

One of the corrective actions proposed was remote monitoring of water quality. In 1997, EPA initiated a study to install a remote monitoring network

Overview of the Case Study

Fort Reno Tank was selected as the first location for remote monitoring system implementation

Four water quality parameters were selected for monitoring in this Case Study - Temperature, Chlorine, Turbidity, pH

The study was later on expanded to two other locations Bryant Street and Blue Plains

The existing WASA’s SCADA system was adapted for data collection

Overview - System Layout

Overview – Publishing Data

Overview – Web Access

Overview – Data Browsing

Overview – Sampling System

Overview – Sample Data

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Resi. CL2 (ppm) pH Temperature (oC) Turbidity (NTU)

System Selection and Implementation

Off-the-shelf online monitoring instrumentation for Temperature, Chlorine, Turbidity and pH with 4-20 mA external outputs were used

A custom water sampling system was built for each site

A Preliminary Assessment for selecting and implementing the appropriate Data Acquisition System was performed. Key factors are outlined as follows:

• Initial and ongoing $ - EPA/WASA

System Selection and Implementation

• Ease of use and programmability - Proprietary

• Hardware Networkable - Yes• System Scalable - Yes• Data/System Redundancy - Yes• System Security – One Way Data Transfer• Remote Access Capability - Not Available • System Response Time - More than

adequate• Historical Trend Data Storage/Transfer

Capability - Limited Storage • Availability of Local Support - WASA

System Selection and Implementation

• Software Features – Graphics, Trending and Reports

• Remote Access - Added a Windows-based PC workstation to dial into using pcAnywhere/ Reachout Software (added security, prevents remote access to the WASA SCADA system)

• Trending - Export Program in Access97• Reporting - Queries to chart in Excel97• Power Availability - Yes

System Selection and Implementation

Summary

• Existing Scalable SCADA System and onsite support

• Programs were developed to work around some of the existing system limitations

• Phased Implementation

Lessons Learned

Train and retrain “hands-on” as much as possible both for operation and troubleshooting activities

Teach operational awareness

Need to customize the user’s manual, provide phone support

Lessons Learned

Frequent changes in WASA support personnel affected some troubleshooting activities

Dead pigeons were found floating in the Fort Reno tank by WASA personnel. The cleaning procedure damaged some of the sensor equipment.

The initial data could not be validated due to the lack of calibration records

Lessons Learned

The network link between the water and sewer side has limited bandwidth. The errors generated in the network traffic using this link frequently cause a bottleneck in the system and eventually led to a few system crashes

Lack of communication between WASA personnel and the contractors working at the Fort Reno site caused the tank to overflow and the sampling system was submerged

Technology Trends Review

Instrumentation

• Conventional – Ion selective electrodes, GC, LC, optical, etc.

• Bio-sentinels based on observing and evaluating the behavior of living organisms - Daphina, Fish, Clam, Bacteria, Algae, etc.

• Bio-sensors - DNA based, flow cytometry, etc.

Technology Trends Review

Instrumentation (Contd.)

• Solid State Microchips• Other (ZAPS)

Remote Data Acquisition Technologies• Wireless – Cellular, CDPD,

Cellmetry/Aeris, Radio’s ISM/VHF/UHF, PCS, Satellite

• Encryption - Key Based – DES/AES symmetric (or secret-key), RSA asymmetric (or public-key) algorithms

Technology Trends Review

Remote Data Acquisition Technologies (Contd.)

• The Polled System:

Pros: Data gathering is simple, no collisions, link failure can easily be detected

Cons: Interrupt type request cannot be handled immediately, wait time increases with the number of locations, all communications must pass through the master.

Technology Trends Review

Remote Data Acquisition Technologies (Contd.)

• The Interrupt System:Pros: Reduces unnecessary transfer of data, quick detection of urgent status information, allows peer-to-peer communication

Cons: Link failure may be detected after a long period of time, operator action is needed to have the latest value, collision of data may occur and cause delays

Technology Trends Review

Power Requirements

• Solar and other power options for instruments and data acquisition equipment

Evaluation of Technologies• USEPA’s T&E Facility, Cincinnati, OH• The New WATERS Center• Field Locations (large and small systems)

Q & A - Discussion

1. What is the intended use of “real-time” monitoring data?

a. Network model calibration, b. Early warning system, or c. Both

Q & A - Discussion

2.What parameters should be monitored, selection criteria for monitoring instrumentation?

a.Conventional (Physio-chemical) - pH, ORP, DO, Turbidity, etc.

b.Biological – Daphnia, fish, clam, otherc.Both

Q & A - Discussion

3.How to select and implement/integrate the various SCADA system components for data collection?

a.Implement new or integrate with existing SCADA system

b.Communication media – Cable/wire, cellular, satellite, RF, etc.

c.Data collection and handling

Q & A - Discussion

4. Intended use and interpretation of real-time data?

a. What do the numbers mean? b. Do we need data filters?c. How do we verify and report the data?

5. Monitoring system maintenance and management?

a. Proper training/retention of peopleb. Instrument calibration and

recordkeepingc. Commitment from management $

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Acknowledgements

• U.S. EPA Support • WASA Support• Shaw Environmental, Inc.