Reagent-less Membrane Sensors Help Streamline Water Quality Monitoring

Sponsored by

The Philadelphia Water Department (PWD) has developed and implemented an online Water Quality Monitoring Network (OWQM) for the city's drinking water distribution system. The purpose of the network is to provide PWD water quality engineers and treatment plant operators the ability to obtain real-time "snap-shots" of water quality conditions, both at key entry points and at strategic locations throughout the distribution system. Practical benefits are early detection of water quality deterioration ahead of customer taps; the ability to document changes for further analysis; a deeper understanding of how water conveyance operations affect water quality; and the seamless integration of a new contamination warning system.

Water quality monitoring panels continuously monitor five water quality parameters selected by PWD. The panels are factory assembled and delivered to monitoring sites ready for installation.
Water quality monitoring panels continuously monitor five water quality parameters selected by PWD. The panels are factory assembled and delivered to monitoring sites ready for installation.

PWD began development of the OWQM in 1999, with a pilot study that included an extensive review of available monitoring technologies. Three sites were selected that were representative of the varying degrees of water quality within the water distribution system. Among the sites selected were a major water transmission main supplying the largest finished water reservoir, the central laboratory service line, and a pumping station located in an area that historically presented some intriguing water quality challenges.

These sites were outfitted with a suite of traditional instruments to monitor total chlorine residual, conductivity, turbidity, pH, temperature, service main pressure, service main flow (where applicable), and instrument board flow. Water quality data was continuously transmitted back to the department's Central Lab Facility either by spread spectrum radio or via the PWD Ethernet.

Although the pilot study was successful, it became apparent that their initial instrument selections presented some significant operational and maintenance challenges. Of particular concern were increased reagent and buffer use and the man-hours required for chlorine and turbidity monitor service and calibration. PWD decided to migrate toward reagent-less membrane chlorine sensors and evaluated various turbidimeters in order to reduce the volume of calibration standards.

In 2002, PWD evaluated water quality instruments from a local manufacturer, Analytical Technology Inc. (ATI), and assembled an array consisting of combined chlorine, conductivity, ORP, turbidity, and pH. The decision to migrate to ATI analyzers and sensors has proven cost effective through reduced on-site service time, cost savings attributed to a reduction in calibration standards usage, and decreased downtime of sensors, which equates.to less breaks in the data stream.

In 2004, with major input from PWD, ATI designed a custom, state-of-the-art water quality panel system that would continuously monitor the five water quality parameters selected by PWD. The system was factory assembled and delivered to monitoring sites for installation and connection to the SCADA system. Between 2004 and 2008, the system was continuously expanded to provide broad distribution system surveillance throughout Philadelphia.

The implementation of this extensive monitoring system with documented reliability played a role in PWD being awarded an EPA Water Security Initiative Grant in 2008. The grant allowed PWD to expand the OWQM sites to monitor for potential contamination of the potable water supply. PWD installed 10 dedicated Contaminant Warning System (CWS) sites in addition to the existing 30 OWQM sites. Each site is outfitted with the standard ATI water quality array and enhanced with a UV254 monitor.

"Philadelphia was selected for this pilot because of its existing water quality protection programs and its commitment to put in place the complex systems needed to increase water security," said William T. Wisniewski, the U.S. EPA's acting administrator for the mid-Atlantic region.

The project is expected to serve as a model for all of the United States' drinking water utility companies. Philadelphia was one of four cities to model this project along with New York City, San Francisco and Dallas.

Analytical Technology will be exhibiting its systems at ACE 13. For more information, visit the company's website, www.analyticaltechnology.com.

Analytical Technology® is an exhibitor at the ACE® '13 event and can be found at Booth No. 14058

More WaterWorld Issue Articles
WaterWorld Articles Archives

Sponsored by

TODAY'S HEADLINES

Voting now underway for WaterWorld's third WaterShots online photo contest

Vote! The voting period for WaterWorld's third WaterShots online photo contest focusing on aging water infrastructure is now underway.

ACE15 opening general session speaker officially announced

The American Water Works Association has officially announced that Dr. Wallace "J" Nichols will serve as the opening general session speaker of the 134th Annual Conference & Exposition, taking place June 7-10 at the Anaheim Convention Center in Anaheim, Calif.

Stanley Consultants earns Engineering Excellence Award for sanitary sewer design

The American Council of Engineering Companies announced that it has given an Engineering Excellence Honor Award to Stanley Consultants for design of the West Side Diversion Tunnel in the city of Davenport, Iowa.

Advanced dredging technology contributes to Gulf barrier island reconstruction

DSC Dredge announced that it has provided an 8-inch Badger Class dredge to J.E. Borries to assist in an ongoing barrier island reconstruction project along a section of the Mississippi coast following the siltation that occurred during Hurricane Isaac in 2012.

FOLLOW US ON SOCIAL MEDIA