While the possibility of chemical or microbial contamination at Hetch Hetchy Reservoir is lower given that its location in Yosemite National Park makes it difficult to access the watershed and no wastewater or urban runoff discharges to the reservoir, the utility recognized the possibility of water quality issues arising after water leaves the treatment plant and travels through the distribution system. With approximately 1,200 miles of mains and 400 million gallons of storage (over 5 days of average demand) spread across dozens of storage facilities, the potential exists for contamination, both intentional and unintentional, as well as other types of water quality and operational issues.
Implementing a comprehensive CWS
Applying EPA Grant funding from 2008 through 2012, SFPUC expanded upon their existing CWS and implemented a comprehensive CWS that comprises the following six features:
Online water quality monitoring stations were set up throughout SFPUC’s distribution system to monitor in real-time a variety of water quality parameters that can be used to indicate contamination. To establish a baseline for its common water quality parameters, SFPUC tested different sensors and software, gleaning insight on the accuracy and precision of the various instruments. The SFPUC utilized EPA’s software, the Threat Ensemble Vulnerability Assessment-Sensor Placement Optimization Tool or TEVA-SPOT, to help identify optimal locations for the sensors that would increase the likelihood of detecting possible contamination within the distribution system. Sites identified by TEVA-SPOT were then evaluated for the required water taps, power, communications, and 24/7 site accessibility.
Sampling and analysis techniques and procedures, which involve collecting water samples throughout SFPUC’s distribution system and testing the samples in the field as well as in the laboratory, were enhanced to reduce the time needed to mobilize emergency responders and to characterize the site where an issue occurred.
Enhanced security monitoring reinforced the value of collaboration between water utilities and local first responders. SFPUC created videos to raise awareness in the San Francisco Police Department (SFPD) of the importance of the drinking water system to the local community, and, consequently, the importance of police response to calls at water system facilities. In the event SFPUC faces an emergency, SFPD and SFPUC are prepared to cooperate and collaborate to protect the City.
Consumer complaint surveillance collects information from consumers who call to report water quality issues. SFPUC enhanced its use of the City’s 24×7 customer service center and telephone number—311—as an effective and cost-efficient way to accurately collect information, as well as improve customer satisfaction through improved tracking, response, and resolution. SFPUC undertook a comprehensive, multimedia public outreach program to inform its customers about using 311 to communicate with the utility.
Public health surveillance usually takes into consideration over-the-counter drug sales and hospital and emergency room admission data as an indicator of waterborne disease outbreaks. Instead, the San Francisco Department of Public Health, working with SFPUC, found more value in establishing a regional framework and protocol for communication, notification, decision-making, and post-contamination event activities over typical data collection strategies due to the delay in data entry and the time-intensive measures required to collect these types of information.
Consequence management plan (CMP) development, and use of associated training and exercises, prepares SFPUC to act in the event that a confirmed contamination incident occurs. Table-top, functional, and full-scale exercises that utilize the CMP are an effective method by which to build relationships across stakeholder groups (e.g., City and County of San Francisco Office of Emergency Services, SFPD, SF Fire Department, Emergency Management Assistance Compact, FBI, Federal Emergency Management Agency, and more). Through workshops, training, and exercises, SFPUC improved its overall communication, coordination, and response with partner agencies to prepare for all types of emergencies.
With its holistic approach, SFPUC’s CWS can detect a broad range of contaminants in enough time that utility operators can effectively respond. By integrating multiple components to monitor the distribution system and water quality, SFPUC attains an overall faster and more accurate detection rate, ultimately ensuring customers get the highest quality drinking water.
Serving as a model for other utilities
Throughout the pilot, SFPUC learned many significant lessons that may be valuable to other utilities considering or implementing similar CWS components or capabilities. SFPUC has significant experience with CWS and formally began to develop its contaminant detection system in 2004. The EPA pilot grant, awarded in 2007 to enhance this system and integrate additional system components, allowed SFPUC to make its CWS one of the most robust in the world.
Ken Thompson serves as CH2M HILL’s deputy global service leader for intelligent water solutions.
Brandon Grissom is an operations analyst with the San Francisco Public Utilities Commission.
For an overview of the pilot program, please see Comprehensive Water Contamination Warning System Demonstration Pilots Serve as Model for Water Utility Community
An overivew of Philadelphia Water Departments CWS pilot project Case Study: Philadelphia Water Department Contaminant Warning System
cc photo courtesy of chrischabot