Presentation on theme: "EARLY WARNING SYSTEMS TO ENSURE DRINKING WATER SAFETY."— Presentation transcript:
EARLY WARNING SYSTEMS TO ENSURE DRINKING WATER SAFETY
Presentation Agenda Vulnerability & sensitivity of drinking water sources Health effects Sources of contamination Early Warning System - »Definition »Structure & Function »Design Consideration »Data Management & Interpretation »Response AquaVerity - CheckLights comprehensive solution Components Competitive edge
Vulnerability and Sensitivity of Drinking Water Sources Surface water Runoff Ground water infiltration Ground water Infiltration from the surface Injection of contaminants Naturally occurring substances
Health effects caused by contaminated source water Acute health effects mainly by - viruses pathogenic bacteria parasites protozoa cysts Chronic health effects mainly by - volatile organic chemicals (VOCs) inorganic chemicals (IOCs) synthetic organic chemicals (SOCs)
Vulnerability Within the Distribution System Backpressure can cause backflow to occur when a potable system is connected to a non-potable supply operating under a higher pressure than the distribution system by means of a pump, boiler, elevation difference, air or steam pressure, or other means. Backflow is any unwanted flow of used or non-potable water, or other substances from any domestic, industrial, or institutional piping system back into the potable water distribution system. Cross-connections and backflow represent a significant public health risk (US EPA, 2000b) by allowing chemical and biological contaminants into the potable water supply (a conclusion of the Microbial/Disinfection Byproducts Federal Advisory Committee (M/DBP FACA)). A wide number and range of chemical and biological contaminants have been reported to enter the distribution system through cross-connections and backflow. Pesticides, sewage, antifreeze, coolants, and detergents were the most frequent types of contaminants reported.
Sources of Contaminants with Acute and Chronic Health Effects Acute: Industrial activities Animal feeding operations Agriculture Septic systems and cesspools Chronic: Industrial & commercial activities Agriculture Landfills & surface impoundments Urban uses
Early Warning System (EWS) Structure & Function An effective EWS is an integrated system for deploying the monitoring technology, analyzing and interpreting the results, and utilizing the results to make decisions that protect public health. An ideal contamination warning system that monitors toxic events in water should have the following features: Rapid Sensitive Wide detection spectrum Reliable Continuous Fit for field testing User-friendly Inexpensive
EWS - Core Criteria Currently, an EWS with all of these features does not exist. However, there are some technologies that can be used to build an EWS that can meet certain core criteria: provide rapid response screen for a number of contaminants while maintaining sufficient sensitivity perform as automated systems that allow for remote monitoring Any monitoring system that does not meet these minimum criteria should not be considered an effective EWS.
EWS Design Considerations There are many issues and water system characteristics that need to be considered when designing an EWS: Planning and Communication System Characterization Target Contaminants
Planning and Communication The objectives of the program should be defined clearly, and a plan should be developed for the- Interpretation Use Reporting of monitoring results. The plan should be developed in coordination with - The water utility Local and state health departments Emergency response units Law enforcement agencies Local political leadership
System Characterization The system should be characterized with respect to - Access points Flow and demand patterns Pressure zones If not already available, a hydraulic model should be constructed. System vulnerabilities should be identified and characterized, preferably through a formal vulnerability assessment.
Target Contaminants Even the most complex array of monitoring equipment cannot detect the entire spectrum of agents that could pose a threat to public health via contaminated water. Thus, the design of an EWS should focus on contaminants that are thought to pose the most serious threat. Many factors may go into this assessment, including: the concentration of a particular contaminant that is necessary to cause harm the availability and accessibility of a contaminant the persistence and stability of a contaminant in an aqueous environment the difficulty associated with detecting a contaminant in the water
EWS - The Tiered Approach A balance between the need for screening function of the system (i.e., the ability to detect a wide range of contaminants) and the need for specificity (i.e., the ability to positively identify and quantify a specific contaminant) can be achieved through tiered monitoring. First tier - continuous, real-time screen for a range of contaminants utilizing a broad-based screening technology such as assays designed to detect changes in toxicity. Second tier - a positive result from the first stage would trigger the second stage of confirmatory analysis using more specific and sensitive techniques. A positive result from the confirmatory analysis would trigger a response action.
Tiered Response Model Increasing: Certainty Response Cost Observed Water Quality Change (determined by broad-based continuous screening) Automated Sample Collection Confirmation Bioassay Chemical Analysis If positive Public health Regulatory or Remedial Action If positive
Broad Based Continuous Screening A major problem in the development of early warning water quality monitoring systems is that there are an almost unlimited number of potential contaminants that could threaten a water asset. While many products have been developed that monitor for specific contaminants or specific types of contaminants, it is impractical to design a system that can detect every potential threat to water quality. One approach is to use biological organisms as living "sentinels" that will warn operators of contamination. Sophisticated continuous and automatic biomonitors are now available that detect and alert whenever a notable change occurs in the behavior of the sensing organisms (such as, bacteria, fish, algae, mussels, daphnia).
Bioassays - Applications & Benefits Mapping to identify toxicity/concentration hotspots Selection of samples for further/more expensive analysis Mapping after pollution incidents/accidents While there are several different organisms that can be used to monitor for toxicity (including bacteria, invertebrates, and fish), bacteria-based bio-sensors are ideal for use as early warning screening tools for drinking water security because bacteria usually respond to toxics in a matter of minutes. [EPA - Biological Sensors for Toxicity-Water and Wastewater Security Product Guide] The Luminescent bacteria provided by CheckLight offer the unique advantage of both automatic and hand held testing capabilities.
EWS Technology Selection Performance of the chosen field deployable monitoring technology must meet the data quality objectives of the monitoring program that were defined during the design of the EWS and include: Specificity Sensitivity Accuracy Precision Recovery False positives/negatives rates
Alarm Levels For the alarms to be triggered at the appropriate levels, one must identify the concentrations at which the agents pose a threat to human health. The basis for setting alarm levels will depend on the capability of the EWS employed. The alarm should be triggered by a combination of events, not a single detection, which may be a false positive.
Sensor Location and Density The location and density of sensors in an EWS is dictated by the results of the system characterization, vulnerability assessment, threat analysis, and usage considerations. Proper characterization of the distribution system, including usage patterns, and the location of critical system nodes (e.g., hospitals, law enforcement and emergency response agencies, government facilities, etc.) is necessary to design an effective monitoring network. However, even if sensors can be optimally located within a distribution system, there may not be sufficient time to prevent exposure of a portion of the public to the contaminated water. At best, monitoring conducted within the distribution system will provide time to limit exposure, isolate the contaminated water, and initiate mitigation/ remediation actions.
Data Management, Interpretation, and Reduction One of the challenges of a continuous, real- time monitoring system is management of the large amounts of data that are generated. Use of data acquisition software and a central data management center is critical. The data management system should be capable of performing some level of data analysis and trending in order to assess whether or not an alarm level has been exceeded and minimize the rate of false alarms. At a minimum, the system should notify operators, public health agencies, and/or emergency response officials. In some cases, it may be appropriate to program the data management system to initiate preliminary response actions, such as closing valves or collecting additional samples. However, these initial responses should be considered simple precautionary measures, and public officials should make judgments regarding decisive response actions. Acknowledgement; this presentation was adopted in part from: Safeguarding The Security Of Public Water Supplies Using Early Warning Systems: A Brief Review.J Hasan et al. Journal Of Contemporary Water Research And Education Issue 129, Pages 27-33, October 2004.
Response The possible responses when an EWS triggers an alarm may include- Modification to the drinking water system (e.g., shutdown, addition of disinfectants, etc.) Notification (e.g., boil water advisory) either to the general public or to target communities or Subpopulations Additional data gathering or monitoring Follow-on surveillance and epidemiologic studies No action, or some combination of these The type of response will be dependent on the nature of both the threat to and the nature of the drinking water system, including the population it serves.
The ETV-Verified ToxScreen Technology Serves as the Basis for the AquaVerity The comprehensive Solution for Water Utilities to Ensure Drinking Water Safety and Quality
AquaVerity Components CCB - Continuous Contamination Biomonitor PCB - Portable Contamination Biomonitor CAS - Control & Analysis Software package SIS - Solution Implementation Service package
Tiered Response Model Increasing: Certainty Response Cost Observed Water Quality Change (determined by broad-based continuous screening) Automated Sample Collection Confirmation Bioassay Chemical Analysis If positive Public health Regulatory or Remedial Action If positive PCB-TOX SPOT CCB-TOC
CheckLights Value Proposition Functional Benefits: Early detection of contamination in drinking water Enabling to pinpoint location & boundaries of contamination sources Reducing direct & indirect costs of illnesses & deaths Saving lives, pain & agony Reducing liability Emotional Benefits: Providing a sense of safety & security Reducing perceived risk of malpractice/liability
For deployment in monitoring stations positioned at strategic locations Includes various monitoring models & re-fill reagent kits (for detecting chemical & biological contaminants) Easily integrated with other systems Suspicious samples are captured by an automatic sampler for further analysis Easy installation, operation and maintenance No need for adjustments due to changing environmental conditions Remotely operated & controlled Requires minimal operator intervention CCB - Continuous Contamination Biomonitor
Enables remote operation and control of multiple CCB units from a control center. Provides tools for long term research and rapid response during emergency situations Software add-ons enable the integration and communication of AquaVerity with 3 rd party devices & management systems (such as SCADA/GIS). CAS – Control & Analysis Software
Graphic display of response to potential heavy metal contaminants Graphic display of response to potential organic contaminants Contamination alert Instrument malfunction All clear CAS – User Interface
How does the AquaVerity solution compare to competitive offers on the market?
EWS Matrix (1)- Detection & Warning Capabilities CheckLights AquaVerity Other Biomonitors Multi-ParameterFactor One million luminescent bacteria 5-20 live organisms5-6 sensorsMethod Wide range of contaminants, including unknown types.5-6 parametersDetection spectrum Yes NoDetermines toxicity YesNo Discrimination between organic & heavy metals Contaminants High Medium (depends on the parameter) Detection sensitivity Yes, by using the portable detectors NoPartialContamination Boundaries assessment
EWS Matrix (2)- Implementation CheckLights AquaVerity Other BiomonitorsMulti-ParameterFactor Very simple to install & maintain. Unattended operation. Complex & requires on going human supervision Complex due to variability of sensors used Installation & maintenance No adjustment needed.Complex Adjustment to changing water environment Wide distribution possible due to simple installation, minimal training & maintenance. Limited distribution due to complexity & costs Limited to wide distribution. Depends on parameters mix & complexity Effective coverage in large water networks Effort is minimal - reagents replacement once a month. Complex - Requires skilled personnel & special training Medium – requires skills & training On-Going usage Very high. Includes built-in control mechanism. Low to Medium. Depends on biota used & environment. conditions Medium. Depends on parameters used. Overall reliability Upgrade re-fill kits with enhanced detection capabilities UnknownunknownFuture Enhancements
EWS Matrix (3) - Cost Effectiveness CheckLights AquaVerity Other BiomonitorsMulti-ParameterFactor MediumMedium to very highLow to very high Depending on chosen parameters Initial capital investment Low due to minimal intervention High due to the required human supervision Medium due to complexity of sensors arrays and baseline build up On going costs Low to mediumHighMedium to highTotal cost of ownership
Positioning Sensitive to a broad range of contamination sources Reliable Cost effective Easy to operate Customer oriented